63672 Federal Register / Vol. 79, No. 206 / Friday, October 24, 2014 / Rules and Regulations 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–R3–ES–2013–0043; 

4500030113: 4500030113] 

RIN 1018–AY01 

Endangered and Threatened Wildlife 

and Plants; Threatened Species Status 

for Dakota Skipper and Endangered 

Species Status for Poweshiek 

Skipperling 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Final rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), determine 

threatened species status under the 

Endangered Species Act of 1973 (Act), 

as amended, for the Dakota skipper 

(Hesperia dacotae), a butterfly currently 

found in Minnesota, North Dakota, 

South Dakota, Manitoba, and 

Saskatchewan and endangered species 

status for the Poweshiek skipperling 

(Oarisma poweshiek), a butterfly 

currently found in Michigan, 

Minnesota, Wisconsin, and Manitoba. 

The effect of this regulation will be to 

add these species to the List of 

Endangered and Threatened Wildlife. 

DATES: This rule becomes effective 

November 24, 2014. 

ADDRESSES: This final rule is available 

on the internet at http://

www.regulations.gov and http://

www.fws.gov/midwest/Endangered/. 

Comments and materials we received, as 

well as supporting documentation we 

used in preparing this rule, are available 

for public inspection at http://

www.regulations.gov. All of the 

comments, materials, and 

documentation that we considered in 

this rulemaking are available by 

appointment, during normal business 

hours at: U.S. Fish and Wildlife Service, 

Twin Cities Field Office, 4101 American 

Boulevard East, Bloomington, 

Minnesota 55425; (612) 725–3548; (612) 

725–3609 (facsimile). 

FOR FURTHER INFORMATION CONTACT: 

Peter Fasbender, Field Supervisor, Twin 

Cities Field Office, 4101 American 

Boulevard East, Bloomington, 

Minnesota 55425; (612) 725–3548; (612) 

725–3609 (facsimile). Persons who use a 

telecommunications device for the deaf 

(TDD) may call the Federal Information 

Relay Service (FIRS) at 800–877–8339. 

SUPPLEMENTARY INFORMATION: 

Executive Summary 

Why we need to publish a rule. Under 

the Endangered Species Act, a species 

may warrant protection through listing 

if it is endangered or threatened 

throughout all or a significant portion of 

its range. Listing a species as an 

endangered or threatened species can 

only be completed by issuing a rule. 

This rule will finalize the listing of the 

Dakota skipper (Hesperia dacotae) as a 

threatened species and the Poweshiek 

skipperling (Oarisma poweshiek) as an 

endangered species. 

The basis for our action. Under the 

Endangered Species Act, we can 

determine that a species is an 

endangered or threatened species based 

on any of five factors: (A) The present 

or threatened destruction, modification, 

or curtailment of its habitat or range; (B) 

Overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) Disease or predation; (D) 

The inadequacy of existing regulatory 

mechanisms; or (E) Other natural or 

manmade factors affecting its continued 

existence. We have determined the 

threats to both species include: 

• Habitat loss and degradation of 

native prairies and prairie fens, 

resulting from conversion to agriculture 

or other development; ecological 

succession and encroachment of 

invasive species and woody vegetation 

primarily due to lack of management; 

past and present fire, haying, or grazing 

management that degrades or eliminates 

native prairie grasses and flowering 

forbs; flooding; and groundwater 

depletion, alteration, and 

contamination. 

• Other natural or manmade factors, 

including loss of genetic diversity, small 

size and isolation of sites, 

indiscriminate use of herbicides such 

that it reduces or eliminates nectar 

sources, climate conditions such as 

drought, direct mortality from fire and 

other management activities or natural 

occurrences, direct or indirect mortality 

from indiscriminate use of pesticides, 

and other unknown stressors. 

• Existing regulatory mechanisms are 

inadequate to mitigate these threats to 

both species. 

Peer review and public comment. We 

sought comments from independent 

specialists to ensure that our 

designation is based on scientifically 

sound data, assumptions, and analyses. 

We invited these peer reviewers to 

comment on our listing proposal. We 

also considered all other comments and 

information received during the 

comment period. 

Previous Federal Action 

Please refer to the proposed listing 

rule for the Dakota skipper and 

Poweshiek skipperling (78 FR 63574; 

October 24, 2013) for a detailed 

description of previous Federal actions 

concerning this species. 

Background 

Please refer to the proposed listing 

rule for the Dakota skipper and the 

Poweshiek skipperling (78 FR 63574; 

October 24, 2013) for a summary of 

species information. 

Status Assessments for Dakota Skipper 

and Poweshiek Skipperling Dakota 

Skipper 

Species Description 

The Dakota skipper (Hesperia 

dacotae) is a member of the skipper 

family Hesperiidae and was first 

described in 1911 from collections taken 

at Volga, South Dakota, and Grinnell, 

Iowa (Skinner 1911 in Royer and 

Marrone 1992a, p. 1). The family 

Hesperiidae comprises seven 

subfamilies worldwide, four of which 

occur in North America, north of 

Mexico (Brower and Warren at http://

tolweb.org/Hesperiidae). There are 21 

recognized species in the genus 

Hesperia (ibid). Dakota skipper is the 

accepted common name for H. dacotae. 

The Dakota skipper is a small to 

medium-sized butterfly with a wingspan 

of 2.4–3.2 centimeters (cm) (0.9–1.3 

inches (in)) and hooked antennae (Royer 

and Marrone 1992a, p. 3). Like other 

Hesperiidae species, Dakota skippers 

have a faster and more powerful flight 

than most butterflies because of a thick, 

well-muscled thorax (Scott 1986, p. 

415). 

Adult Dakota skippers have variable 

markings. The dorsal surface of adult 

male wings ranges in color from tawnyorange to brown and has a prominent 

mark on the forewing; the ventral 

surface is dusty yellow-orange (Royer 

and Marrone 1992a, p. 3). The dorsal 

surface of adult females is darker brown 

with diffused tawny orange spots and a 

few diffused white spots restricted to 

the margin of the forewing; the ventral 

surfaces are dusty gray-brown with a 

faint white spotband across the middle 

of the wing (Royer and Marrone 1992a, 

p. 3). Adult Dakota skippers may be 

confused with the Ottoe skipper (H. 

ottoe), which is somewhat larger with 

slightly longer wings (Royer and 

Marrone 1992a, p. 3). Dakota skipper 

pupae are reddish-brown, and the larvae 

are light brown with a black collar and 

dark brown head (McCabe 1981, p. 181). 


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General Life History 

Dakota skippers are univoltine 

(having a single flight per year), with an 

adult flight period that may occur from 

the middle of June through the end of 

July (McCabe 1979, p. 6; McCabe 1981, 

p. 180; Dana 1991, p. 1; Royer and 

Marrone 1992a, p. 26; Skadsen 1997, p. 

3; Swengel and Swengel 1999, p. 282). 

The actual flight period varies 

somewhat across the range of each 

species and can also vary significantly 

from year to year (e.g., Rigney 2013a, p. 

138), depending on temperature 

patterns (Bink and Bik 2009, Koda and 

Nakamura 2012). Females emerge 

slightly later than males (Dana 1991, p. 

15, Rigney 2013a, p. 138), and the 

observed sex ratio of Dakota skippers 

was roughly equal during peak flight 

periods (Dana 1991, p. 15; Swengel and 

Swengel 1999, pp. 274, 283). 

The Dakota skipper flight period in a 

locality lasts 2 to 4 weeks, and mating 

occurs throughout this period (Braker 

1985, p. 46; McCabe and Post 1977, pp. 

36–38; McCabe 1979, p. 6; McCabe 

1981, p. 180; Dana 1991, p. 15; Swengel 

and Swengel 1999, p. 282; Rigney 

2013a, p. 138). Adult male Dakota 

skippers exhibit perching behavior 

(perch on tall plants to search for 

females), but occasionally appear to 

patrol in search of mating opportunities 

(Royer and Marrone 1992a, p. 25). 

Dakota skippers lay eggs on broadleaf 

plants (McCabe 1981, p. 180) and 

grasses (Dana 1991, p. 17), although 

larvae feed only on grasses. Potential 

lifetime fecundity is between 180 and 

250 eggs per female Dakota skipper; 

realized fecundity depends upon 

longevity (Dana 1991, p. 26). Female 

Dakota skippers lay eggs daily in 

diminishing numbers as they age (Dana 

1991, pp. 25–26). Dana (1991, p. 32) 

estimated the potential adult life span of 

Dakota skipper to be 3 weeks and the 

average life span (or residence on site 

before death or emigration) to be 3 to 10 

days on one Minnesota prairie. 

Dakota skippers overwinter as larvae 

and complete one generation per year. 

Dakota skipper eggs hatch after 

incubating for 7–20 days; therefore, 

hatching is likely completed before the 

end of July. Recent research at the 

Minnesota Zoo demonstrated that, 

under controlled conditions in the 

laboratory, Dakota skippers eggs 

hatched after 11 to 16 days, and the 

majority of the caterpillars hatched on 

the 13th and 14th days (Runquist 2014, 

pers. comm.). After hatching, Dakota 

skipper larvae crawl to the bases of grass 

plants where they form shelters at or 

below the ground surface with silk, 

fastened together with plant tissue 

(Dana 1991, p. 16). They construct 2–3 

successively larger shelters as they grow 

(Dana 1991, p. 16). The larvae emerge 

from their shelters at night to forage 

(McCabe 1979, p. 6; McCabe 1981, p. 

181; Royer and Marrone 1992a, p. 25) 

and appear to clip blades of grass and 

bring them back to their shelters to 

consume (Dana 2012a, pers. comm.). 

Dakota skippers have six or seven 

larval stages (instars) (Dana 1991, pp. 

14–15) and overwinter (diapause) in 

ground-level or subsurface shelters 

during either the fourth or fifth instar 

(McCabe 1979, p. 6; McCabe 1981, pp. 

180, 189; Dana 1991, p. 15; Royer and 

Marrone 1992a, pp. 25–26). In the 

spring, larvae resume feeding and 

undergo two additional molts before 

they pupate. During the last two instars, 

larvae shift from buried shelters to 

horizontal shelters at the soil surface 

(Dana 1991, p. 16). 

Food and Water 

Nectar and water sources for adult 

Dakota skippers vary regionally and 

include purple coneflower (Echinacea 

angustifolia), blanketflower (Gaillardia 

aristata), black-eyed Susan (Rudbeckia 

hirta), purple locoweed (Oxytropis 

lambertii), bluebell bellflower 

(Campanula rotundifolia), prairie 

milkvetch (Astragalus adsurgens) (syn. 

A. laxmannii), and yellow sundrops 

(Calylophus serrulatus) (Dana 1991; 

McCabe and Post 1977, pp. 36–38; 

Royer and Marrone 1992a, p. 21; Rigney 

2013a, p. 142). Plant species likely vary 

in their value as nectar sources due to 

the amount of nectar available during 

the adult flight period (Dana 1991, p. 

48). Nectar source preferences are 

typically indicated as the relative 

proportion of plants selected for 

nectaring among all the available 

species in a particular area. Swengel 

and Swengel (1999, pp. 280–281) 

observed nectaring at 25 plant species, 

however, most of the nectaring was at 

purple coneflower and blanketflower. 

Dana (1991, p. 21) reported the use of 

25 nectar species in Minnesota with 

purple coneflower most frequented; 

McCabe (1979, p. 42; McCabe 1981, p. 

187) observed Dakota skippers using 

eight nectar plants. Dakota skippers in 

Manitoba were recently observed 

nectaring on 12 species of plants, 

primarily black-eyed Susan, but also 

including 6 species that were previously 

unrecorded as nectar flowers: White 

sweetclover (Melilotus alba), purple 

prairie clover (Petalostemon purpureus), 

yellow evening-primrose (Oenothera 

biennis), palespike lobelia (Lobelia 

spicata), fiddleleaf hawksbeard (Crepis 

runcinata), and upland white aster 

(Solidago ptarmicoides) (Rigney 2013a, 

pp. 4, 57). In addition to nutrition, the 

nectar of flowering forbs provides water 

for Dakota skipper, which is necessary 

to avoid desiccation during flight 

activity (Dana 1991, p. 47; Dana 2013, 

pers. comm.). Some plant species listed 

in some studies as nectar flowers are 

likely used for perching and patrolling 

rather than as nectar sources. 

The flight of the adult female 

typically extends beyond that of males 

(Dana 2014, pers. comm.; Dana 1991, 

pp. 1,15; Rigney 2013a, p. 138); 

therefore the two sexes can visit the 

same nectar plant species at different 

rates (e.g., if the flowering period is 

more coincident with either the male or 

the female flight period). For example, 

Dana (1991, p. 21) observed a greater 

number of males than females visiting 

purple locoweed—this plant is already 

past its flowering peak at the beginning 

of the male flight and nearly finished 

flowering by the peak female flight 

(Dana 2014, pers. comm.). 

Dakota skipper larvae feed on several 

native grass species; little bluestem 

(Schizachyrium scoparium) is a frequent 

food source of the larvae (Dana 1991, p. 

17; Royer and Marrone 1992a, p. 25), 

although they have been found on 

Dichanthelium spp., and other native 

grasses (Royer and Marrone 1992a, p. 

25). When presented with no other 

choice, Dakota skipper larvae may feed 

on a variety of native and nonnative 

grasses (e.g., Kentucky bluegrass (Poa 

pratensis)) at least until diapause (Dana 

1991, p. 17). The timing of growth and 

development of grasses relative to the 

larval period of Dakota skippers are 

likely important in determining the 

suitability of grass species as larval host 

plants. Large leaf blades, leaf hairs, and 

the distance from larval ground shelters 

to palatable leaf parts preclude the value 

of big bluestem and Indian grass as 

larval food plants, particularly at 

younger larval stages (Dana 1991, p. 46). 

In captivity, Dakota skipper larvae ate 

big bluestem (Andropogon gerardii), at 

older larval stages, and prairie dropseed 

(Sporobolus heterolepis) (Runquist 

2014, pers. comm.). Captive larvae also 

fed on smooth brome (Bromus inermis) 

(Dana 1991, p 17), but this was not 

tested in a natural setting and the 

structural features of this grass would 

hinder or prevent larval survival (Dana 

2013, pers. comm.). The tight empirical 

correlation between occurrence of 

Dakota skippers and the dominance of 

native grasses in the habitat, indicates 

that population persistence requires 

native grasses for survival (Dana 2013, 

pers. comm.). 


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Dispersal 

Dakota skipper are not known to 

disperse widely; the species was 

evaluated among 291 butterfly species 

in Canada as having relatively low 

mobility. Experts estimated Dakota 

skipper to have a mean mobility of 3.5 

(standard deviation = 0.7) on a scale of 

0 (sedentary) to 10 (highly mobile) 

(Burke et al. 2011, p. 2279; Fitzsimmons 

2012, pers. comm.). Dakota skippers 

may be incapable of moving greater than 

1 kilometer (km) (0.6 miles (mi)) 

between patches of prairie habitat 

separated by structurally similar 

habitats (e.g., crop fields, grassdominated fields or pasture, but not 

necessarily native prairie) (Cochrane 

and Delphey 2002, p. 6). Royer and 

Marrone (1992a, p. 25) concluded that 

Dakota skippers are not inclined to 

disperse, although they did not describe 

individual ranges or dispersal distances. 

McCabe (1979, p. 9; 1981, p. 186) found 

that concentrated activity areas for 

Dakota skippers shift annually in 

response to local nectar sources and 

disturbance. 

In a mark–recapture study, average 

adult movements of Dakota skipper 

were less than 300 meters (m) (984 feet 

(ft)) over 3–7 days; marked adults 

crossed less than 200 m (656 ft) of 

unsuitable habitat between two prairie 

patches and moved along ridges more 

frequently than across valleys (Dana 

1991, pp. 38–40). Dana (1997, p. 5) later 

observed reduced movement rates 

across a small valley dominated by 

exotic grasses compared with 

movements in adjacent widespread 

prairie habitat. Roads and crop fields 

were suspected as impediments for 

movement among prairie patches along 

two sites of the main valley (Dana 1997, 

p. 5), although movements beyond the 

study area were beyond the scope of the 

1997 mark–recapture study (Dana 2013, 

pers. comm.). Skadsen (1999, p. 2) 

reported possible movement of Dakota 

skippers in 1998 from a known 

population at least 800 m (2625 ft) away 

to a site with an unusually heavy 

growth of purple coneflower; he had not 

found Dakota skippers in three previous 

years when coneflower production was 

sparse. The two sites were connected by 

native vegetation of varying quality, 

interspersed by a few asphalt and gravel 

roads (Skadsen 2001, pers. comm.). 

In summary, the best information we 

have suggests that dispersal of Dakota 

skipper is very limited due in part to its 

short adult life span and single annual 

flight. Therefore, the species’ extirpation 

from a site is likely permanent unless it 

is within about 1 km (0.6 mi) of a site 

that generates a sufficient number of 

emigrants or is artificially reintroduced 

to a site; however, the capability to 

propagate the Dakota skipper is 

currently lacking. 

Habitat 

Dakota skippers are obligate residents 

of undisturbed (remnant, untilled) highquality prairie, ranging from wet-mesic 

tallgrass prairie to dry-mesic mixedgrass prairie (Royer and Marrone 1992a, 

pp. 8, 21). High-quality prairie contains 

a high diversity of native plant species, 

including flowering herbaceous plants 

(forbs). Royer and Marrone (1992a, p. 

21) categorized Dakota skipper habitat 

into two main types that were once 

intermixed on a landscape scale, but are 

now mostly segregated. The first, 

referred to as ‘‘Type A’’ by Royer et al. 

(2008, pp. 14–16), is low wet-mesic 

prairie that occurs on near-shore glacial 

lake deposits. Type A Dakota skipper 

habitat is dominated by bluestem 

grasses, with three other plant species 

almost always present and blooming 

during Dakota skipper’s flight period: 

Wood lily (Lilium philadelphicum), 

bluebell bellflower, and mountain 

deathcamas (smooth camas; Zigadenus 

elegans) (McCabe 1981, p. 190). This 

habitat type has a high water table and 

is subject to intermittent flooding in the 

spring, but provides ‘‘sufficient relief to 

provide segments of non-inundated 

habitat during the spring larval growth 

period within any single season’’ (Royer 

et al. 2008, p. 15). Common forbs in 

bloom during the late season in Type A 

habitat include Rocky Mountain blazing 

star (Liatris ligulistylis), Canada 

goldenrod (Solidago canadensis), strict 

blue-eyed grass (Sisyrinchium 

montanum), common goldstar (Hypoxis 

hirsuta), and black-eyed Susan (Lenz 

1999, p. 6). Type A habitats also contain 

small patches of dry-mesic prairie 

inhabited by Dakota skippers. Common 

forb species in these dry-mesic areas 

include stiff sunflower (Helianthus 

pauciflorus Nutt. ssp. pauciflorus) and 

candle anenome (Anemone cylindrica), 

although purple coneflower was rare in 

these habitats (Lenz 1999, pp. 6–11). 

Dakota skipper inhabits Type A habitat 

in north-central North Dakota, southeast 

North Dakota, and Manitoba. 

The second Dakota skipper habitat 

type, referred to as ‘‘Type B’’ by Royer 

et al. (2008, p. 14), occurs on rolling 

terrain over gravelly glacial moraine 

deposits and is dominated by bluestems 

and needle grasses (Heterostipa spp.). 

As with Type A habitat, bluebell 

bellflower and wood lily are also 

present in Type B habitats, but Type B 

habitats also support more extensive 

stands of purple coneflower, upright 

prairie coneflower, and common 

gaillardia (Royer and Marrone 1992a, p. 

22). Both Type A and Type B prairies 

may contain slightly depressional (low 

topographical areas that allow for the 

collection of surface water) wetlands 

with extensive flat areas and slightly 

convex hummocks, which are dryer 

than the wet areas (Lenz 1999, pp. 4, 8). 

In northeastern South Dakota, Dakota 

skippers inhabit primarily Type B 

habitats with abundant purple 

coneflower, but they also occur in 

nearby Type A habitats in some areas 

(Skadsen 1997, p. 4). All Type A 

habitats occupied by Dakota skipper in 

South Dakota are near hill-prairie (Type 

B) habitats that are managed with fall 

haying (Skadsen 2006b, p. 2). 

Little bluestem and porcupine grass 

(Hesperostipa spartea) are the 

predominant grass species in Dakota 

skipper habitat in South Dakota 

(Skadsen 2006b, p. 2). Dry-mesic 

prairies suitable for Dakota skippers in 

South Dakota typically include little 

bluestem, side oats grama, porcupine 

grass, needle-and-thread grass 

(Hesperostipa comata), and prairie 

dropseed, and a high diversity and 

abundance of forbs, including purple 

coneflower, purple prairie clover, white 

prairie clover, yellow sundrops, prairie 

groundsel (Packera plattensis), prairie 

milkvetch, eastern pasqueflower 

(Pulsatilla patens), old man’s whiskers 

(prairie smoke, Geum triflorum), 

western silver aster (Symphyotrichum 

sericeum), dotted blazing star (Liatris 

punctata), tall blazing star (L. asper), 

meadow zizia (Zizia aptera), blanket 

flower, prairie sagewort (Artemisia 

frigida), and leadplant (Amorpha 

canescens) (Skadsen 2006b, pp. 1–2). 

Purple coneflower occurs at all sites 

where the Dakota skipper has been 

recorded in South Dakota, although it is 

absent at some sites where Dakota 

skipper is abundant in other States 

(Skadsen 2006b, p. 2). 

In Minnesota, Dakota skippers often 

inhabit Type B habitats, however, the 

species has been documented in Type A 

habitats, particularly in Kittson and 

Stearns counties. Dana (1997, p. 8) 

described typical habitat in Minnesota 

as dry-mesic prairie dominated by midheight grasses with an abundance of 

nectar sources including purple 

coneflower and prairie milkvetch 

(Astragalus laxmannii Jacq. var. 

robustior). Southern dry prairies in 

Minnesota are described as having 

sparse shrub cover (less than 5 percent) 

composed primarily of leadplant, with 

prairie rose (Rosa arkansana), 

wormwood sage, or smooth sumac 

(Rhus glabra) present and few, if any, 

trees (Minnesota DNR 2012a). Dana 

(1991, p. 21) never encountered Dakota 


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skippers in wet or wet-mesic prairies in 

Minnesota, despite abundance of 

suitable plants and the frequent use of 

these habitats by similar skipper 

species. In systematic surveys at 12 

Minnesota sites, Swengel and Swengel 

(1999, pp. 278–279) found that Dakota 

skippers were significantly more 

abundant on dry prairie than on either 

wet-mesic prairie. 

In Manitoba, Dakota skipper habitat 

has been described as Type A prairies, 

where the species tends to occupy the 

slightly higher, drier areas of wet-mesic 

prairie where nectar sources are more 

abundant (Webster 2003, p. 7). Recent 

studies classify Dakota Skipper sites in 

Manitoba as tallgrass or medium to 

tallgrass prairies that have been subject 

to minimal disturbance, generally 

consisting of higher, dryer prairies 

adjacent to lower areas with sedges 

(Rigney 2013a, p. 155). Inhabited areas 

are dominated by native grasses and 

sites are generally characterized as 

having the following plant species: Big 

bluestem, little bluestem 

(Schizachyrium scoparius), tufted hair 

grass (Deschampsia caespitosa), 

switchgrass (Panicum virgatum), 

Cusick’s bluegrass (Poa cusickii), 

porcupine grass, common spikerush 

(Eleocharis palustris), wood lily (Lilim 

philadelphicum), wild onion (Allium 

stellatum), mountain death camas 

(Zygadenus elegans), death camas 

(Zygadenus gramineus), common gold 

star (Hypoxis hirsute), wild prairie rose, 

American licorice (Glycyrrhiza 

lepidota), white prairie clover 

(Petalostemon candidum), purple 

prairie clover, Seneca snake root 

(Polygala senega), meadow zizia, 

northern bedstraw (Galium boreale), 

harebell, palespike lobelia, common 

yarrow (Achillea millefolium), pale 

agoseris (Agoseris glauca), heath aster 

(Aster ericodes) or white prairie aster 

(A. falcatus), smooth aster (Aster laevis), 

Flodman’s thistle (Cirsium flodmanii), 

fiddle leaf hawksbeard, eastern daisy 

fleabane (Erigeron annuus), Maximilian 

sunflower (Helianthus maximilianii), 

Nuttall’s sunflower (Helianthus 

nuttallii), meadow blazing star, blackeyed Susan, upland white aster, and 

stiff goldenrod (Solidago rigida) (Rigney 

2013a, pp. 155–156). 

Occupied habitats in Saskatchewan 

are similar to the drier upland dry-mesic 

mixed-grass prairie hillside habitats in 

Manitoba, which is dominated by 

bluestems and needlegrass. The Dakota 

skipper was most common on ridgetops 

and hillsides near purple coneflower 

(Webster 2003, p. 8). 

In North Dakota, an association of 

bluestems (Schizachyrium scoparium, 

Andropogon gerardii) and 

needlegrasses, typically invaded by 

Kentucky bluegrass, typifies dry-mesic 

Dakota skipper habitat in the rolling 

terrain of river valleys and the Missouri 

Coteau (Royer and Marrone 1992a, p. 

22). These prairies, located on the 

western edge of the species’ known 

range, typically contain wood lily, 

bluebell bellflower, coneflowers, and 

other asters as nectar sources; in some 

areas, mountain deathcamas also occurs 

(Royer and Marrone 1992a, p. 22). The 

location of larval food plants rarely 

seems to affect Dakota skipper 

distribution within habitats because 

these warm-season grasses are usually 

dominant and evenly dispersed 

(Swengel 1994, p. 6), although invasion 

by smooth brome grass and other 

invasive species may displace or 

extirpate native larval food plants 

(Culliney 2005, p. 134; Bahm et al. 

2011, p. 240; LaBar and Schultz 2012, 

p. 177). 

Two key factors, soils unsuitable for 

agriculture and steep topography, have 

allowed remnant native-prairie habitats 

inhabited by Dakota skippers to persist 

(Royer and Marrone 1992a, p. 22). 

McCabe (1979, pp. 17–18; 1981, p. 192) 

and Royer et al. (2008, p. 16) have 

linked the historical distribution of 

Dakota skippers to surface geological 

features and soils that are glacial in 

origin and, possibly, regional 

precipitation-evaporation ratios (ratio of 

evaporation occurring naturally in one 

location over a given area compared to 

the amount of precipitation, such as rain 

and snow, falling over the same area). 

Soil types typical of Dakota skipper sites 

were described as sandy loams, loamy 

sand, or loams (Lord 1988 in Royer et 

al. 2008, pp. 3, 10). Additional edaphic 

(soil) features, such as soil moisture, 

compaction, surface temperature, pH, 

and humidity, may be contributing 

factors in larval survival and, thus, 

important limiting factors for Dakota 

skipper populations (Royer et al. 2008, 

p. 2). For example, edaphic parameters 

measured in sites throughout the range 

of Dakota skipper and occupied by the 

species included a bulk density (an 

indicator of soil compaction) that 

ranged from 0.9g/cm3 to 1.3 g/cm3 and 

mean soil pH that ranged from 6.3 to 6.7 

with high micro-scale variation 

(variation on a small scale) (Royer et al. 

2008, p. 10). Soil texture ranged from 4 

to 12 percent clay, 53 to 74 percent 

sand, and 14 to 39 percent silt (Royer et 

al. 2008, p. 12). Seasonal soil 

temperatures, measured at three depths 

(20, 40, and 60 cm (8, 16, and 24 in)) 

were the same at all depths within a 

site; occupied Minnesota sites generally 

had higher soil temperatures at all 

depths than occupied sites in North 

Dakota or South Dakota (Royer et al. 

2008, p. 11). Royer did not measure 

these parameters in unoccupied sites. 

Rigney (2013a, pp. 108–109) 

measured edaphic features at 8 sites in 

Manitoba occupied by the species and 

broadly characterized the soil 

compaction (at 10 cm) as 570 to 990 

kPA, bulk density ranging from 0.75 to 

1.30 kg/L, mean soil surface air 

temperature at 18 °C during Julian 

weeks 28–39 (continuous count of 

weeks since the beginning of the 

calendar year), and mean relative 

humidity at 85 percent during the same 

time period. Soils were classified as clay 

loams and sandy loams, with generally 

low to moderate compaction (<1375 

kPA) and bulk densities, which is 

indicative of little or no compacting 

forces from cattle grazing, tilling, or 

agricultural vehicles (Rigney 2013a, pp. 

104, 119). 

Royer (2008, pp. 2, 16) hypothesized 

that Dakota skipper larvae are 

particularly vulnerable to desiccation 

(drying out) during dry summer months 

and require ‘‘vertical water distribution’’ 

(movement of shallow groundwater to 

the soil surface) in the soils or wet low 

areas to provide relief from high 

summer temperatures. Humidity may 

also be essential for larval survival 

during winter months since the larvae 

cannot take in water during that time 

and depend on humid air to minimize 

water loss through respiration (Dana 

2013, pers. comm.). Royer (2008, pp. 

14–15) measured microclimalogical 

levels (climate in a small space, such as 

at or near the soil surface) within 

‘‘primary larval nesting zones’’ (0 to 2 

cm (0 to 0.8 inches) above the soil 

surface) throughout the range of Dakota 

skippers, and found an acceptable 

rangewide seasonal (summer) mean 

temperature range of 18 to 21 °C (64 to 

70 °F), rangewide seasonal mean dew 

point ranging from 14 to 17 °C (57 to 63 

°F), and rangewide seasonal mean 

relative humidity between 73 and 85 

percent. Royer (2008) only examined 

occupied areas for these parameters; 

therefore, the statistical and biological 

significance of these edaphic variables 

cannot be determined from his study. 

Species Occupancy 

We generally consider the Dakota 

skipper or Poweshiek skipperling to be 

‘‘present’’ at sites where the species was 

detected during the most recent survey, 

if the survey was conducted in 2002 or 

more recently and there is no evidence 

to suggest the species is now extirpated 

from the site (e.g., no destruction or 

obvious and significant degradation of 

the species’ habitat), with the exception 


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of the following four sites. We consider 

the species to be present at one 

Poweshiek skipperling site in Michigan 

where the species was observed at the 

site in 1996, and no further surveys 

have been conducted. This site, 

however, still has suitable habitat for 

the species according to species experts 

in the State and at least one other 

species of prairie-fen-dependent 

butterfly is present (Hosler 2013, pers. 

comm.). Therefore, the Poweshiek 

skipperling is most likely still present at 

this site. We also consider the Dakota 

skipper to be present at one site 

(Chanarambie Creek in Minnesota) 

where the most recent survey was from 

1994. At this site, no evidence suggests 

the species is not still present because, 

based on a species-expert review of the 

site, the habitat and management is still 

conducive to the species (Dana 2013, 

pers. comm.). Additional sites where we 

consider Dakota skipper to be present 

include two sites in Minnesota with 

1996 records (Bluestem Prairie and 

Buffalo River State Park). Although no 

survey for the species has taken place at 

Bluestem Prairie since 1996, a 2012 

assessment of the habitat at the site 

indicates that this site is a high-quality 

prairie that contains the native prairie 

flora conducive to the Dakota skipper 

(Selby 2012, p. 9). The site at Buffalo 

River State park, which adjoins 

Bluestem Prairie, has not been surveyed 

since 1996, but recent habitat 

assessments show that it still contains 

prairie habitats with the native prairie 

flora conducive to the species (MN DNR 

2013, unpubl.). Furthermore, the species 

expert in Minnesota supports that the 

species is most likely still present at 

these sites. 

We assigned a status of ‘‘unknown’’ if 

the species was found in 1993 or more 

recently, but not in the most recent one 

to two sequential survey year(s) since 

1993 and there is no evidence to suggest 

the species is now extirpated from the 

site (e.g., no destruction or obvious and 

significant degradation of the species’ 

habitat). We considered a species to be 

‘‘possibly extirpated’’ at sites where it 

was detected at least once prior to 1993, 

but not in the most recent one to two 

sequential survey years(s). A species is 

also considered ‘‘possibly extirpated’’ at 

sites where it was found prior to 1993 

and no surveys have been conducted in 

1993 or more recently. At least three 

sequential years of negative surveys, no 

matter what years they were conducted, 

were necessary for us to consider the 

species ‘‘extirpated’’ from a site, because 

of the difficulty of detecting these 

species, as explained further in this 

section. A species is also considered 

‘‘extirpated’’ at sites where habitat for 

the species is no longer present. If the 

species is considered to be extirpated 

from a site, the occupancy status would 

not change unless the species is 

detected at that location during future 

surveys. 

When determining whether the 

species occupancy is unknown, possibly 

extirpated, or extirpated at a particular 

site, we used the survey year 1993 as a 

cut-off date, because most known sites 

(more than 81 percent of known 

Poweshiek skipperling sites and more 

than 86 percent of known Dakota 

skipper sites) have been surveyed at 

least once since 1993, and survey data 

more than 20 years old may not reflect 

the current status of a species or its 

habitat at a site (for example, due to 

habitat loss from secondary succession 

of woody vegetation or a change in plant 

communities due to invasive species). 

Although it cannot be presumed that the 

species is absent at sites not surveyed 

since 1993, the likelihood of occupancy 

of these sites should be considered 

differently than sites with more recent 

survey data (e.g., due to woody 

vegetation succession over time). When 

analyzing survey results, we disregarded 

negative surveys conducted outside of 

the species’ flight period (outside of 

June or July) or under unsuitable 

conditions (e.g., high wind speeds over 

approximately 16 miles-per-hour). We 

accepted survey data from those 

surveyors with whom we were 

confident in their ability to identify the 

species in the field. 

After we applied these standards to 

initially ascertain the status of the 

species, we asked species experts and 

Service personnel to help verify, 

modify, or correct species’ occupancy at 

each site (particularly for sites with 

questionable habitat quality or those 

that have not been surveyed recently). 

In most cases, we used the status 

confirmed during expert review, unless 

we received additional information (e.g., 

additional survey or habitat data 

provided after the expert reviews) that 

suggests a different status at a particular 

site. 

Timing of surveys is based on initial 

field checks of nectar plant blooms and 

sightings of butterfly species with 

synchronous emergence (sightings of 

butterfly species that emerge at the same 

time as Dakota skipper and Poweshiek 

skipperling), and, more recently, 

emergence estimated by a degree-day 

emergence model using high and low 

daily temperature data from weather 

stations near the survey sites (Selby, 

undated, unpublished dissertation). 

Surveys are conducted during flight 

periods when the species’ abundance is 

expected to be at levels at which the 

species can be detected. However, as 

with many rare species, detection 

probabilities are imperfect and some 

uncertainty remains between nondetection and true absence (Gross et al. 

2007, pp. 192, 197–198; Pellet 2008, pp. 

155–156). Three sequential years of 

negative surveys is sufficient to capture 

variable detection probabilities, since 

each survey year typically encompasses 

more than one visit (e.g., the average 

number of visits per Dakota skipper site 

per year ranges from 1 to 11), and the 

probability of false absence after 5–6 

visits drops below 5 percent for studied 

butterfly species with varying average 

detection probabilities (Pellet 2008, p. 

159). Therefore, the site is considered 

‘‘extirpated’’ if there are three sequential 

years of negative surveys (preferably, 

each year has more than one survey 

date). 

It cannot be presumed that the species 

is not persisting at a site only because 

there have not been recent surveys. At 

several sites, the species has persisted 

for longer than 20 years; for example, 

Dakota skipper was first recorded at 

Scarlet Fawn Prairie in South Dakota in 

1985 and has had positive detections 

(the species was detected during a 

survey) every survey since that date. 

The most recent detection was in 2013. 

The year 1993 was chosen based on 

habitat-related inferences, specifically, 

the estimated time for prairie habitat to 

degrade to non-habitat due to woody 

encroachment and invasive species. For 

example, native prairies with previous 

light-grazing management that were 

subsequently left idle transitioned from 

mixed grass to a mix of woody 

vegetation and mixed grass in 13 years 

and it was predicted that these idle 

prairies would be completely lost due to 

woody succession in a 30-year 

timeframe (Penfound 1964, pp. 260– 

261). The time for succession of idle 

prairie depends on numerous factors, 

such as the size of the site, edge effects 

(the changes that occur on the boundary 

of two habitat types), and the plant 

composition of adjacent areas. 

This approach is the most objective 

way to evaluate the data range-wide. 

Most sites have been surveyed over 

multiple years, although the frequency 

and type of surveys varied among sites 

and years. Surveys were conducted 

using various protocols (e.g., Pollard 

walks (Pollard 1975), modified Pollard 

walks, wandering transects, timed 

transects) depending on the objective of 

the survey, funding or available 

resources, and staff. In several cases, 

species experts provided input on 

occupancy based on their familiarity 


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with the habitat quality and stressors to 

populations at particular sites. 

To summarize, there are few sites 

with relatively older data where we 

consider the species to still be present. 

In general, most Poweshiek skipperling 

sites with a present status have had a 

positive detection in 2008, or more 

recently with a few exceptions. At one 

Poweshiek skipperling site, the species 

was observed at the site in 1996, and no 

further surveys have been conducted. 

The remaining Poweshiek skipperling 

sites where the species is considered 

present have had detections in 2013, 

except four sites where the species was 

detected in 2008, 2010, 2011, or 2012, 

and no further surveys have occurred. 

Likewise, in general, most Dakota 

skipper sites with a present status have 

had a positive detection in 2002, or 

more recently, with a few exceptions. At 

four Dakota skipper sites we consider 

the species to be present with the most 

recent record from 2001 or earlier 

including one site where the most 

recent survey was from 1994, and two 

sites with 1996 records. No evidence 

suggests that the species is not still 

present at these sites because the best 

information indicates that the site’s 

habitat is still conducive to the 

butterfly, and, therefore, the species 

may still be present there. We also 

consider Dakota skipper to be present at 

the following sites: 17 sites in Canada 

that were surveyed most recently in 

2002; 1 additional site with a 2002 

detection of the species and a favorable 

habitat assessment in 2012; 1 site with 

a 2003 detection; 1 site with a 2005 

detection; 1 site with a 2006 detection; 

19 sites in Canada that were surveyed 

most recently in 2007; 2 additional sites 

with a 2007 detection; 1 site with a 

positive detection in 2008; 3 sites with 

a positive detection in 2009; 23 sites 

with positive detections in 2012; and 10 

sites with positive detections in 2013. 

Population Distribution and Occupancy 

Status 

Once found in native prairies in five 

States and two Canadian provinces, the 

Dakota skipper and its habitat have 

undergone dramatic declines; the 

species is now limited to native prairie 

remnants in three States and two 

Canadian provinces. The Dakota skipper 

is presumed extirpated from Illinois and 

Iowa and no longer found in eastern 

Minnesota. Populations persist in a few 

locations in western Minnesota, 

northeastern South Dakota, North 

Dakota, southern Manitoba, and 

southeastern Saskatchewan. Royer and 

Marrone (1992a, p. 5) speculated that 

Dakota skippers may also occur in far 

eastern Montana and southeastern 

Saskatchewan, in habitats similar to 

those occupied by the species in 

northwestern North Dakota. The Dakota 

skipper was subsequently found in 

Saskatchewan in 2001 after 40 years of 

searching (Hooper 2002, pers. comm.), 

but no actual records have been found 

in Montana and Royer (2002, pers. 

comm.) no longer thinks that the species 

ever occured in Montana. 

From its earliest identification, the 

Dakota skipper was considered rare 

(Royer and Marrone 1992a, p. 1), 

although considerable destruction of its 

habitat likely occurred even before the 

species was first described in 1911. 

Habitat destruction and degradation has 

greatly fragmented Dakota skipper’s 

range from its core through its northern 

and western fringes (McCabe 1981, p. 

179; Royer and Marrone 1992a, p. 28; 

Schlicht and Saunders 1994, p. 1; Royer 

1997, p. 2; Schlicht 1997a, p. 2; Schlicht 

1997b, p. 2; Skadsen 1997, pp. 25–26; 

Skadsen 1999c, p. 15; Swengel and 

Swengel 1999, p. 267). The historical 

distribution of Dakota skippers may 

never be precisely known because 

‘‘much of tallgrass prairie was 

extirpated prior to extensive ecological 

study’’ (Steinauer and Collins 1994, p. 

42), such as butterfly surveys. 

Destruction of tallgrass and mixed-grass 

prairie began in 1830 (Samson and 

Knopf 1994, p. 418), but significant 

documentation of the ecosystem’s 

butterfly fauna did not begin until about 

1960. Therefore, most of the species’ 

decline probably went unrecorded. 

Based on records of vouchered 

specimens, however, we know that 

Dakota skipper range has contracted 

northward out of Illinois and Iowa. The 

species was last recorded in Illinois in 

1888 (McCabe 1981, p. 191) and in Iowa 

in 1992 (Orwig and Schlicht 1999, p. 6). 

Britten and Glasford’s (2002, pp. 363, 

372) genetic analyses support the 

presumption that this species formerly 

had a relatively continuous distribution; 

the small genetic divergence (genetic 

distance) among seven sites in 

Minnesota and South Dakota indicate 

that populations there were once 

connected. Dakota skipper dispersal is 

very limited due in part to its short 

adult life span and single annual flight. 

Therefore, the species’ extirpation from 

a site is likely permanent unless it is 

within about 1 km (0.62 mi) of a site 

that generates a sufficient number of 

emigrants or is artificially reintroduced 

to a site. 

The Dakota skipper’s range once 

comprised native prairie in five States 

and Canada, extending from Illinois to 

Saskatchewan; it now occurs only in 

native prairie remnants in portions of 

three States and two Canadian 

provinces. Of the 264 historically 

documented sites, there are 83 sites 

where we consider the Dakota skipper 

to be present, 88 sites with unknown 

status, 41 possibly extirpated sites, and 

52 that are considered extirpated (Table 

1). Approximately 47 percent (39 of 83) 

of the sites where the species is 

considered to be present are located in 

Canada, mostly within three isolated 

complexes, and were observed in 2002, 

or in 2007 with no subsequent surveys. 

Four additional locations where we 

consider the species to be present in 

Manitoba had positive detections of the 

species as recently as 2012 (Rigney 

2013a, p. 117). The remaining 42 sites 

where the species is considered to be 

present are about equally distributed 

among Minnesota (11 sites), North 

Dakota (16 sites), and South Dakota (14 

sites). Researchers made positive 

detections of the species in 10 of these 

sites in 2013. The species was observed 

at 19 of these sites in 2012. Other U.S. 

sites with a present status with 

relatively older positive detections and 

no subsequent surveys for the species 

include one site with a positive 

detection in 1994, two sites with 

positive detections in 1996, one site 

with a positive detection in 2002, one 

site with a positive detection in 2005, 

one site with a positive detection in 

2006, two sites with a positive detection 

in 2007, one site with a positive 

detection in 2008, and three sites with 

a positive detection in 2009. At several 

of these sites, the habitat has been 

assessed more recently than they were 

surveyed for the species. The 

distribution and status of Dakota 

skipper in each State of known 

historical or extant occurrence are 

described in detail below. 


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TABLE 1—NUMBER OF HISTORICALLY DOCUMENTED DAKOTA SKIPPER SITES WITHIN EACH STATE AND THE NUMBER OF

SITES WHERE THE SPECIES IS THOUGHT TO BE PRESENT, UNKNOWN, POSSIBLY EXTIRPATED, OR EXTIRPATED

State 

State’s 

percentage 

of the total 

number of 

historical 

sites 

Present Unknown Possibly 

extirpated Extirpated Total 

Illinois ............................................................................... 0.4 .................... .................... .................... 1 1 

Iowa .................................................................................. 1.1 3 3 

Minnesota ......................................................................... 26.1 11 28 18 12 69 

North Dakota .................................................................... 20.5 16 14 11 13 54 

South Dakota ................................................................... 32.6 14 45 10 17 86 

Manitoba .......................................................................... 14.0 28 1 2 6 37 

Saskatchewan .................................................................. 5.3 14 0 0 0 14 

Total Number of Historically Documented Sites .............. .................... 83 88 41 52 264 

Percent of the Total Number of Historical Sites by 

Occupancy ............................................................ .................... 32 33 15 20 ....................

Illinois 

Dakota skippers are considered to be 

extirpated from Illinois. The species was 

last recorded near Chicago in 1888 

(McCabe 1981, p. 191). 

Iowa 

There are three historical records of 

Dakota skippers in three counties in 

Iowa (Dickinson, Poweshiek, and 

Woodbury), but the species is presumed 

extirpated from the State (Schlicht and 

Orwig 1998, pp. 84–85; Selby 2004a, pp. 

1, 5; Selby 2012, pers. comm.; Nekola 

and Schlicht 2007, p. 9). The species 

was last seen at Cayler Prairie 

(Dickinson County) in 1992, but surveys 

of this site in 2000, 2004, 2005, and 

2007 were negative, so we presume it to 

be extirpated from that site (Schlicht 

and Orwig 1998, p. 85; Selby 2004a, p. 

5; Selby 2006a, p. 5; Selby 2008, p. 6). 

The species was not observed at eight 

sites surveyed in the period 1988–1997 

(Swengel and Swengel 1999, pp. 288– 

289), at eight sites surveyed in 2004 

(Selby 2004a, p. 5), nor during extensive 

surveys at 32 sites in 2007 (Selby 2008, 

p. 6). 

Minnesota 

Minnesota historically contained 

about 26 percent of the sites where the 

Dakota skipper has been recorded (Table 

1) (Service 2014, unpubl. geodatabase). 

Since the earliest known record (1965) 

of the species in Minnesota, 66 sites 

have been recorded in the State, but 

recent surveys indicate that the species 

is declining in the State (Service 2014, 

unpubl. geodatabase). Of the 69 known 

locations of Dakota skipper in 

Minnesota; the species is extirpated or 

possibly extirpated from 30 of those 

sites, and the status is unknown at 28 

others (Service 2014, unpubl. 

geodatabase). The Dakota skipper is 

considered to be present at 11 sites in 

Minnesota in 3 counties: Clay, Lincoln, 

and Murray, although 2 of those sites 

have not been surveyed since 1996, and 

1 site has not been surveyed since 1994. 

McCabe (1981, p. 187) observed very 

stable population numbers in Minnesota 

prairies that he visited repeatedly 1968– 

1979. On dry-mesic prairie in Lincoln 

County, Minnesota, Dana (Dana 1997, 

pp. 3–5) also observed stable numbers 

into the thousands during his intensive 

studies from 1978 to 1983. Schlicht 

(1997a, p. 13) and Reiser (1997, p. 16) 

reported more variable numbers on the 

same sites in 1995–1996, and based on 

these more recent observations, Dana 

(1997, pp. 3–5) suggested that 

populations could experience 

significant size fluctuations between 

years. At Hole-in-the-Mountain 

preserve, Minnesota, Dana (1991, pp. 

36–37) found peak abundance of 

approximately 1,000 Dakota skippers 

over about 40 ha (98 ac); he estimated 

that 2,000–3,000 individuals may have 

been alive at various times during the 

flight period and that only one-third to 

one-half of adults were alive 

simultaneously. Where they occur, these 

high adult densities persist for only 

about a week to 10 days during the 

single annual flight period (Selby and 

Glenn-Lewin 1989, pp. 24–28). 

The percentage of sites surveyed each 

year in Minnesota with positive 

detections remained relatively stable 

from 1985 to 2005, with an average 

detection rate of 67 percent for all 

survey years with more than one site 

surveyed (excluding sites newly 

discovered in the first year it was 

discovered), an average of 70 percent 

detection rate for survey years with 5 or 

more sites surveyed and an average of 

66 percent detection rate for survey 

years with 10 or more sites surveyed. 

One exception to the high detection 

rates was 1994; only 26 percent (5 of 19 

sites) of sites surveyed in 1994 resulted 

in positive detections. Recent surveys of 

the species resulted in significantly 

lower than average positive detections. 

The percent of sites surveyed each year 

with positive detections has recently 

decreased from 70 percent (7 of 10 sites) 

in 2005, to 47 percent (8 of 17 sites) in 

2007, 56 percent (10 of 18 sites) in 2008, 

6 percent (1 of 16 sites) in 2012, and to 

7 percent (1 of 15 sites) in 2013 (for 

years with greater than 10 sites 

surveyed, see Figure 1). Only one 

individual was detected in Minnesota 

during 2012 surveys, which included 18 

sites with previous records and 23 

prairie remnants without previous 

records for the species (Dana 2012c, 

pers. comm.; Runquist 2012a, pers. 

comm.; Olsen 2012, pers. comm.). 

Dakota skippers were detected at 1 site 

in Minnesota during 2013 surveys, 

which included 15 sites with previous 

records and 12 prairie remnants without 

previous records for the species 

(Runquist 2014, pp. 3–6; Selby 2014, pp. 

2–5; Rigney 2013b, p. Appendix B; 

Service 2014, unpubl. geodatabase.). 

The cause for this sharp decline is 

unknown. 


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The Dakota skipper is presumed 

extirpated at 12 sites in Minnesota; at 7 

of these sites the species has not been 

observed since 1984 or earlier. Four 

sites at which the species is now 

presumed to be extirpated have had 

fairly recent positive observations. The 

species was last observed at Prairie 

Waterfowl Production Area (WPA) in 

Big Stone County in 2000 (Skadsen 

2000, p. 1), for example, but was not 

found in 2008 (Selby 2009a, p. i), 2010, 

and 2012 (Service 2014, unpubl. 

geodatabase). Dakota skippers were 

observed at the Glacial Lakes WPA in 

2001 (Schlicht 2001b, p. 18), but the 

species was not observed in 2003, 2004, 

and 2005 (Selby 2006b, p. Appendix A 

xii); the species is now considered to be 

extirpated at that site (Service 2014, 

unpubl. geodatabase). The last 

observation of Dakota skipper at the Big 

Stone National Wildlife Refuge (NWR) 

in Lac Qui Parle County was in 2000, 

and it was not observed during surveys 

in 2009, 2011, or 2012 (Skadsen 2012a, 

p. 5). Dakota skippers were observed at 

Chippewa Prairie in 1995, but not in 

1996, 2005, and 2012 (Service 2014, 

unpubl. geodatabase). Of the 18 sites 

where the species is possibly extirpated, 

4 have not been surveyed since the 

species was last seen in 1989 or earlier. 

Dakota skippers at two of the sites 

where the species is possibly extirpated 

have not been observed since 1991 

(Service 2014, unpubl. geodatabase). 

One site, with a positive detection in 

1998, was ranked as ‘‘possibly 

extirpated’’ based on expert opinion. 

The remaining 11 sites had positive 

observations prior to 1993, were 

surveyed once more recently, and had a 

negative observation (Service 2014, 

unpubl. geodatabase). 

The status of the Dakota skipper is 

unknown at 28 sites; Dakota skipper 

have not been observed at 14 of these 

sites since the mid- to late 1990s, 

despite one or two years of survey effort 

at several sites. The remaining 14 sites 

with unknown status have had positive 

observations in 2007 or more recently, 

but are given this designation due to one 

or two subsequent negative surveys. For 

example, Dakota skipper was 

documented at the Gens Prairie in 

Murray County and Woodstock Prairie 

in Pipestone County in 2007, but the 

species was not observed during surveys 

in 2008 or 2013 (Selby 2009a, p. 

Appendix 5 li, xxxiii and Appendix 4 

xlix; Selby 2014, p. 5). 

In 2007 and 2008, the Minnesota DNR 

carried out a broad survey effort to 

assess the status of Dakota skipper and 

other prairie butterflies in the State after 

experts noted significant declines in 

these species in west-central Minnesota 

beginning in 2003 (Selby 2006b, p. 30). 

Researchers surveyed 17 and 19 sites 

with previous Dakota skipper records in 

2007 and 2008, respectively; Dakota 

skipper was found at 8 sites each year 

and at 1 site where it had not previously 

been recorded (Selby 2009a, p. 6). The 

surveys confirmed Dakota skipper’s 

extirpation from one site in Cottonwood 

County, where it was last recorded in 

1970. 

A parallel study in 2007 (Dana 2008) 

consisted of more intensive work at a 

few sites thought to contain some of the 

State’s most viable populations of 

Dakota skipper. Among these sites was 

The Nature Conservancy’s Hole-in-theMountain preserve in Lincoln County, 

which was the only Minnesota 

population rated as secure in 2002 

(Cochrane and Delphey 2002, p. 16). 

The 2007 surveys indicated that the site 

still supported a substantial population, 

but that it may have decreased in size 

since earlier studies were conducted 

(Dana 1991, p. 36; Dana 2008, p. 18). 

Dakota skippers were not detected 

during the 2012 or 2013 flight periods 

(Runquist 2012, pp. 13–14, 18–20; 

Runquist 2012a, pers. comm., Selby 

2014, p. 5); therefore, we consider the 

status of the species at the Hole-in-theMountain preserve to be unknown. 


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Relatively important populations of 

Dakota skipper in Minnesota may still 

occur at the Prairie Coteau, Felton 

Prairie, and Glacial Lakes complexes, 

but the 2012 and 2013 survey results 

raised concern for the species’ status at 

Prairie Coteau. The number of Dakota 

skippers encountered per 100 m (328 ft) 

of transect at Prairie Coteau State 

Natural Area (SNA) were 1.7 in 1990 

and 1.1 in 2007 (Dana 2008, p. 19). No 

Dakota skippers were observed at Prairie 

Coteau SNA during the 2012 or 2013 

flight periods (Runquist 2012, pp. 9–10); 

therefore, we consider the status of the 

species to be unknown at that site. Selby 

(2009b, Appendix 4, p. iv) recorded 14 

Dakota skippers during a 5-hour survey 

in 2007 at the Felton Prairie SNA. 

During a 1-hour survey in 2008, nine 

Dakota skippers were recorded and with 

little indication of any substantial 

change since the previous year (Selby 

2009b, Appendix 5, p. iv); Felton Prairie 

was resurveyed in 2013, and no Dakota 

skippers were observed (Service 2014, 

unpubl. geodatabase). The number of 

Dakota skippers recorded during recent 

surveys at Glacial Lakes State Park has 

been low despite good habitat 

conditions. An apparently widespread 

population was present as recently as 

2001 when Skadsen (2001, p. 24) found 

Dakota skippers along almost all of 40 

km (25 mi) of transect in and around the 

park—he recorded as many as 31 Dakota 

skippers along one transect (Skadsen 

2001, p. 24). Selby (2009a, p. 1 and 1iv) 

surveyed the same areas in 2007 and 

2008, describing habitat at survey sites 

as good to excellent, but recorded only 

eight Dakota skippers during about 7 

hours of surveys in and around the park 

(Selby 2009a, p. 1 and 1iv). Glacial 

Lakes State Park surveys conducted in 

2012 were outside of the Dakota skipper 

flight period (Runquist 2012a, pers. 

comm.), and the species was not 

detected in 2013 (Selby 2014, p. 5). 

In summary, the Dakota skipper is 

now considered to be extirpated or 

possibly extirpated from at least 30 of 

the 69 sites in Minnesota, which 

historically contained approximately 26 

percent of all known historical Dakota 

skipper locations rangewide (Table 1). 

The species is considered to be present 

and unknown at 12 and 27 sites, 

respectively. However, only one 

individual male was detected in the 

State during 2012 surveys, which 

included 18 sites with previous records; 

2012 surveys for undiscovered 

populations were also carried out on 23 

prairie remnants without previous 

records for the species. Only 6 

individual Dakota skipper were 

observed in 2013 surveys in Minnesota, 

which included 15 sites with previous 

records; 2013 surveys for undiscovered 

populations were also carried out on 12 

prairie remnants without previous 

records for the species (Service 2014, 

unpubl. geodatabase). Similar surveys of 

prairie remnants with no previous 

documentation of Dakota skipper were 

completed in Minnesota in 2007 and 

2008. Based on these surveys, the 

likelihood that significant undiscovered 

Dakota skipper populations occur in 

Minnesota is low. 

North Dakota 

North Dakota historically contained 

approximately 21 percent of all known 

historical locations of Dakota skippers 

rangewide (Table 1); the State contained 

54 historical sites distributed among 18 

counties (Service 2014, unpubl. 

geodatabase). The Dakota skipper is 

currently present at 16 sites in 5 North 

Dakota counties, of these, 11 occur 

within the Towner-Karlsruhe complex 

in McHenry County, 1 is within the 

Sheyenne National Grasslands complex 

in Ransom County, 2 are in northern 

McKenzie County, and 1 site is in Wells 

County. Of the 16 sites where we 

consider the Dakota skipper to be 

present, 15 sites had positive 

observations of the species in 2012. The 

remaining site had positive observations 

in 2002. The status of the species is 

unknown at 14 sites; 10 of these sites 

have not had positive records since the 

mid- to late 1990s, and the other 4 sites 

had positive records between 2001 and 

2003. The Dakota skipper is presumed 

extirpated from 13 sites and 4 counties, 

primarily due to heavy grazing, weed 

control, and other disturbances (e.g., 

bulldozing at Killdeer Mountain to 

reduce aspen growth, Royer 1997). The 

species is possibly extirpated from 11 

additional sites and 3 additional 

counties. 

Researchers surveyed 25 sites, 

believed to possibly have Dakota 

skipper populations, in 2012; of these 

sites, 23 had previous records of the 

species (Royer and Royer 2012a, entire). 

Thirteen of the 25 surveyed sites had 

Dakota skipper present (Royer and 

Royer 2012a, pp. 3–4; Royer and Royer 

2012b, pp. 2–3). One new site was 

found in 2012 (Royer and Royer 2012a, 

p. 33), adjacent to a site with previous 

records but with different landownership, so the researcher considered 

it a new site. Another new site was 

found in North Dakota in 2012, in Wells 

County, where two observations were 

made—possibly the same individual 

(HDR, Inc. 2012, pp. 21–23). At sites 

with Dakota skipper, lower average 

encounter frequencies were observed 

across the State in 2012 (State average 

= 9.4 encounters per hour) than during 

the 1996–1997 statewide surveys (State 

average = 17.4 encounters per hour) 

(Royer and Royer 2012b, p. 5; Royer and 

Royer 2012a. pp. 7–8). Three sites with 

previous Dakota skipper records in 

North Dakota were surveyed during the 

2013 flight period; the species was not 

detected in any of those surveys (Fauske 

2013 data (in ND National Guard 2013, 

in litt.; HDR Engineering 2013, pp. 10– 

11). 

Of the Dakota skipper populations in 

North Dakota, none may be secure, 

although the Towner-Karlsruhe complex 

was considered to be the stronghold for 

the species in the State in 2002 

(Cochrane and Delphey 2002, p. 17), 

and most of the sites where the species 

is currently present are still occupied by 

‘‘viable populations’’ (Royer 2012a, 

pers. comm.). All of the habitat where 

the species is present in the TownerKarlsruhe complex is Type A (wetmesic) habitat (Royer and Marrone 

1992a, pp. 21–22; Royer et al. 2008, pp. 

14–16). Three sites within the TownerKarlsruhe complex are owned by the 

North Dakota State Land Department, 

and the remaining nine sites with extant 

populations are privately owned. Some 

Towner-Karlsruhe sites are linked by 

highway rights-of-way that contain 

native prairie vegetation and by other 

prairie remnants (Royer and Royer 

2012a, p. 18). In 2002, none of these 

sites were described as secure (Cochrane 

and Delphey 2002, pp. 66–67) since 

each is subject to private or State 

management options that could 

extirpate Dakota skipper from the site. 

In 1999, it was estimated that about 30 

percent of the Towner-Karlsruhe area 

still contained native prairie (Lenz 1999, 

p. 2); more recent observations indicate 

that several native prairie sites have 

been invaded to varying extents by 

nonnative species, such as leafy spurge, 

Kentucky bluegrass, and alfalfa 

(Medicago sativa), and several are 

subject to intense grazing or early 

haying (Royer and Royer 2012b, pp. 5– 

6, 7–10, 13–16, 18–19, 22–23; Royer 

2012, in litt.). 

Dakota skipper populations in the 

Sheyenne National Grasslands complex 

have experienced intensive grazing, 

leafy spurge (Euphorbia esula) invasion, 

and the effects of herbicides used to 

control leafy spurge and grasshoppers 

(Royer 1997, pp. 15 and 27). For 

example, McCabe (1979, p. 36) cited the 

McLeod Prairie in the Sheyenne 

Grasslands in southeastern North 

Dakota as the best site for Dakota 

skippers in North Dakota. Since then, 

however, leafy spurge invasion has 

significantly modified the habitat, and 

the Dakota skipper is now extirpated 


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from the site (Royer 1997, p. 14). 

Swengel and Swengel (1999, p. 286) did 

not find Dakota skippers at eight survey 

sites in the Sheyenne grasslands during 

1988–1997, although Royer did observe 

a few isolated Dakota skippers in the 

Sheyenne National Grasslands during 

this period (e.g., Royer 1997, pp. 14–15). 

Dakota skippers were recorded at one 

new site (Gregor) in the Sheyenne 

National Grasslands in 2001 (Spomer 

2004, pp. 14–15). The status of Dakota 

skipper at the Gregor site is currently 

unknown, since the species was not 

observed during the 2002 survey (Royer 

and Royer 2012a, pp. 3–4). 

Orwig (1996, p. 3) suggested that 

Brown’s Ranch in Ransom County, 

owned by The Nature Conservancy, had 

potential to support a metapopulation 

(groups of local populations 

interconnected by dispersal habitat) in 

the Sheyenne River watershed. More 

recently, however, Spomer (2004, p. 36) 

found that the population there was not 

doing well, and Royer failed to find the 

species in 2012 (Royer and Royer 2012a, 

p. 3). Therefore, the status of the species 

at the Brown Ranch site is unknown. 

Royer (1997, pp. 15 and 27) claimed 

that, throughout the Sheyenne 

Grasslands, both public and private 

lands have been so heavily grazed and 

altered by grasshopper and leafy spurge 

control that extirpation of Dakota 

skippers from the area is almost certain 

to occur. The population at Venlo 

Prairie, for example, deteriorated from 

good/fair in 2001 to poor in 2003 due 

to intense grazing and disappearance of 

flowers (Spomer 2004, pp. 9, 12); the 

species is now considered to be 

extirpated at that site. The population at 

Garrison Training Area in McLean 

County is now considered unknown due 

to negative surveys in 2004 and 2013 

(Fauske 2004, p. 1; Fauske 2013 in ND 

National Guard 2013, in litt.). 

In 2002, experts ranked all sites 

outside of the two complexes discussed 

above as threatened or vulnerable; most 

were small and isolated populations 

threatened by conversion and invasive 

species (Cochrane and Delphey 2002, 

pp. 66–67). Most of these sites are now 

considered extirpated or possibly 

extirpated. Today, only 3 sites outside 

of the Towner-Karsruhe Complex and 

Sheyenne National Grasslands 

complexes are thought to have extant 

(present) Dakota skipper populations. In 

addition to the Towner-Karsruhe 

Habitat Complex sites in McHenry 

County, only 2 of the 25 sites surveyed 

by Royer in 2012, both in northern 

McKenzie County, may have ‘‘viable 

populations’’ (Royer 2012b, pers. 

comm.), although only one individual 

was observed at each site in 2012 (Royer 

and Royer 2012b, pp. 16–17). Only three 

sites with previous records were 

surveyed in North Dakota during the 

2013 flight period, and the Dakota 

skipper was not observed (Fauske 2013 

in ND National Guard 2013, in litt.; HDR 

Engineering 2013, pp. 10–11). 

In summary, North Dakota contains 

approximately 21 percent (N = 54) of all 

known historical locations of the 

species rangewide; however, the current 

occupancy status of the Dakota skipper 

is unknown at 14 sites, and it is 

considered to be extirpated or possibly 

extirpated from at least 24 of the 54 

known sites in the State (Table 1). The 

species is considered to be present at 16 

sites in the State. North-central North 

Dakota may hold hope for the species’ 

long-term conservation. Dakota skipper 

was detected at 13 of the 25 sites 

surveyed during 2012 (23 of the sites 

had previous Dakota skipper records); 

average encounter frequencies observed 

across the State in 2012 (9.4 encounters 

per hour), however, were lower than 

during the 1996–1997 State-wide 

surveys (ND State average = 17.4 

encounters per hour) using the same 

methodology. The species was not 

detected at the three sites surveyed in 

2013. 

Although only a small fraction of all 

grassland in North Dakota has been 

surveyed for Dakota skippers, a 

significant proportion of the unsurveyed area is likely not suitable for 

Dakota skipper. The species was never 

detected at approximately 108 

additional locations in North Dakota 

that were surveyed for the species in the 

period 1991–2013 (USFWS 2014, 

unpubl. geodatabase). Many of these 

sites have been surveyed multiple times 

over multiple years (USFWS 2014, 

unpubl. geodatabase). Surveys for the 

Dakota skipper are typically conducted 

only in areas where floristic 

characteristics are indicative of their 

presence. New potential sites surveyed 

are generally focused on prairie habitat 

that appears suitable for the species and 

has a good potential of hosting the 

species, in other words, sites are not 

randomly selected across the landscape. 

Therefore, researchers have a higher 

likelihood of detecting the species at 

these sites than at sites randomly 

selected across the landscape. Based on 

these surveys, the likelihood that 

significant numbers of undiscovered 

Dakota skipper populations occur in 

North Dakota is low. Moreover, data 

available from the numerous sites that 

have been surveyed are likely to be 

representative of areas that have not 

been surveyed—that is, population 

trends and the nature and extent of 

stressors that may impact the 

populations in un-surveyed areas can 

reasonably be inferred by analyzing data 

collected from the sites that have been 

surveyed. 

South Dakota 

South Dakota historically contained 

approximately 33 percent of all known 

locations of Dakota skippers rangewide 

(Table 1). Since the earliest known 

record of Dakota skipper (1905) in South 

Dakota, 86 sites have been documented 

across 11 counties in the State, but 

recent surveys indicate that the species 

is declining in the State (Service 2014, 

unpubl. geodatabase). Of the 86 

historical sites, Dakota skipper is 

presumed extirpated from 17 sites and 

2 counties (Brown and Moody), and is 

possibly extirpated from 10 additional 

sites. Dakota skipper is considered 

present at 14 sites, and the status of the 

species is unknown at 45 sites. Twentyseven sites in South Dakota with 

previous Dakota skipper records were 

surveyed in 2012; the species was 

detected at 9 of those sites (Service 

2014, unpubl. geodatabase). Eight 

additional sites within the species’ 

historical range were surveyed during 

the 2012 flight period, which resulted in 

the discovery of two new nearby Dakota 

skipper sites (Service 2014, unpubl. 

geodatabase; Skadsen 2012a, pers. 

comm.). Twenty-eight sites in South 

Dakota with previous Dakota skipper 

records were surveyed in 2013; the 

species was detected at 9 of those sites 

(Service 2014, unpubl. geodatabase). 

Ten additional sites within the species’ 

historical range were surveyed during 

the 2013 flight period, which resulted in 

no new Dakota skipper sites discovered 

(Service 2014, unpubl. geodatabase). 

The proportion of positive surveys at 

known sites has fluctuated over time; 

however, the 2012 and 2013 surveys 

had the lowest positive detection rate 

(35 percent and 32 percent, 

respectively) for the last 16 years (since 

1996), much less than comparable 

survey years (years with 10 or more sites 

surveyed) in South Dakota. 

While there are some sites with earlier 

records, most South Dakota sites were 

initially documented during extensive 

surveys conducted during 1996 to 1998. 

Forty-eight locations without previous 

records were surveyed during 2002– 

2004, which resulted in the discovery of 

20 new Dakota skipper sites in 

northeastern South Dakota (Skadsen 

2003, p. 8; Skadsen 2004, pp. 3–6), but 

due to more recent negative surveys, the 

occupancy of the species is currently 

unknown or extirpated at many of these 

sites (Skadsen 2011, p. 5; Skadsen 

2012b, pp. 4–5; Skadsen, 2012, pers. 

comm.; Skadsen 2003, p. 10; Skadsen 


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2004, p. 2; Skadsen 2006a, p. 2, 10; 

Skadsen 2006b, p. 5; Skadsen 2007, p. 

3; Skadsen 2008, p. 3, 12; Skadsen 2009, 

p. 3). Additional survey effort resulted 

in the discovery of nine new sites 

between 2005 and 2012, with a 

maximum of three new sites discovered 

in 2006 (Skadsen 2010a, p. 6; Skadsen 

2012b, pp. 4–5; Skadsen 2012, pers. 

comm.; Skadsen 2005, pp. 5–6, Skadsen 

2006a, p. 12; Skadsen 2006b, p. 5; 

Skadsen 2007, p. 3; Skadsen 2008, p. 9; 

Skadsen 2009, p. 2). Eight additional 

sites without previous documentation of 

the species were surveyed in 2012, 

which resulted in the discovery of two 

nearby sites (Service 2014, unpubl. 

geodatabase). To summarize, new sites 

have been discovered in South Dakota 

during most survey years since 2002, 

however, the number of new sites 

discovered each year has been low 

recently; two or three new sites have 

been discovered each survey year since 

2005 (three sites in 2005, two sites in 

2006, two sites in 2007, zero sites in 

2010, two sites in 2012, and zero sites 

in 2013). The rate that known sites are 

becoming extirpated is higher than the 

rate of new discovery—the occupancy of 

the species at many sites is now 

unknown or extirpated due to more 

recent negative surveys. 

The species has never been 

documented in Clark County, but 

because few surveys have been 

conducted there, the county may 

contain undiscovered populations 

(Skadsen 2006b, p. 1). Skadsen (2012b, 

pers. comm.) doubts the existence of 

public lands with suitable Dakota 

skipper habitat in Clark County and has 

not received permission to survey a few 

possible suitable locations that are 

privately owned. 

Although only a small fraction of all 

grassland in eastern South Dakota has 

been surveyed for Dakota skippers (e.g., 

Dakota skipper surveys have been 

conducted on less than approximately 

30,000 acres (12,140 ha) in South 

Dakota within the species range (Service 

2014, unpubl. geodatabase)), a 

significant proportion of the unsurveyed area may not be suitable for 

the Dakota skipper, based on surveys in 

additional areas of possible habitat 

where the species was not detected . For 

example, there is an estimated 1,620,549 

acres (ac) (655,813 hectares (ha)) of 

unbroken (untilled) grasslands that may 

provide habitat for the Dakota skipper in 

the nine counties where the Dakota 

skipper is considered be present or to 

have unknown occupancy in South 

Dakota (HAPET 2012, unpubl. data). 

Additional areas of unbroken prairie 

were estimated in three other counties 

where the species may have occurred 

historically (HAPET 2012, unpubl. 

data). While these lands represent 

unbroken grassland in South Dakota, the 

models used to identify unbroken 

grassland are not able to identify plant 

species, plant species composition, 

floristic quality, or presence of invasive 

species (Loesch 2013, pers. comm.). 

Therefore, it is not known if these 

unbroken grasslands contain the 

specific native prairie plants that the 

Dakota skipper requires (as discussed in 

detail in the Background section of this 

proposed rule) and, therefore, may not 

equate to suitable habitat for the species. 

The species was never detected at 

approximately 79 additional locations 

in South Dakota that were surveyed 

from 1991 through 2013 (USFWS 2014, 

unpubl. geodatabase). Several of these 

sites have been surveyed multiple times 

in one year or during multiple years 

(USFWS 2014, unpubl. geodatabase). 

Surveys for Dakota skipper are typically 

conducted only in areas where floristic 

characteristics are indicative of their 

presence. For example, in South Dakota, 

Skadsen (1997, p. 2) selected for surveys 

dry-mesic prairie that supported purple 

coneflower and wet-mesic prairie that 

supported wood lily and mountain 

deathcamas based on searches for these 

sites by car and reports from resource 

managers. Only sites with landowner 

permission are accessed for surveys, 

however, new potential sites surveyed 

are generally focused on prairie habitat 

that appears suitable for the species and 

has a good potential of hosting the 

species, in other words, sites are not 

randomly selected across the landscape. 

Therefore, researchers have a higher 

likelihood of detecting the species at 

these sites than at sites randomly 

selected across the landscape. Based on 

these surveys, the likelihood that 

significant undiscovered Dakota skipper 

populations occur in South Dakota is 

low. Moreover, data available from the 

numerous sites that have been surveyed 

are likely to be representative of areas 

that have not been surveyed—that is, 

population trends and the nature and 

extent of stressors that may impact the 

populations in un-surveyed areas can 

reasonably be inferred by analyzing data 

collected from the sites that have been 

surveyed. 

Since there is little long-term 

quantitative data for sites in South 

Dakota, we examined presence–absence 

(non-detection) data over time. The 

percent of sites surveyed each year with 

positive detections of the species 

remained relatively stable from 1985 to 

2010, with an average positive detection 

rate of 63 percent for all survey years 

with more than one site surveyed 

(excluding new sites for the first year of 

discovery), an average positive detection 

rate of 60 percent for survey years with 

at least 5 sites surveyed, and an average 

positive detection rate of 71 percent for 

survey years with at least 10 sites 

surveyed. One exception to the high 

detection rates was during the 1991 

survey year when none (0 of 7 sites) of 

the sites surveyed in 1991 resulted in 

positive detections of the species, 

excluding 3 new sites that were 

discovered that year. Another exception 

was in 1996, when 2 of the 8 sites with 

previous records surveyed had a 

positive detection; however, 6 new sites 

were discovered that year. The detection 

rate remained relatively stable until 

2010, when the percent of sites with 

positive detections fell from 89 percent 

(8 of 9 sites) in 2010, to 46 percent (5 

of 11 sites) in 2011, 35 percent (9 of 26 

sites) in 2012, and 32 percent (9 of 28 

sites) in 2013 (Figure 2). These types of 

fluctuations had been observed in prior 

years; therefore, it is difficult to 

determine a clear trend in the data using 

positive detections—the last two survey 

years may fall within the normal range 

of variation. 


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The Outer Coteau des Prairies 

subsection of the North Central 

Glaciated Plains section of Bailey’s Ecoregions is thought to be a stronghold for 

Dakota skipper, since nearly 34 percent 

of the total documented Dakota skipper 

sites are within that subsection (89 of 

the 264 documented sites—Service 

2014, unpubl. geodatabase). Most of 

these Outer Coteau des Prairie sites are 

in South Dakota; 73 of the 86 Dakota 

skipper sites in South Dakota are within 

the Outer Coteau des Prairies subsection 

(Service 2014, unpubl. geodatabase). 

Dakota skipper is considered to be 

present at only 9 of those 73 sites—the 

species status is unknown at 40 of those 

sites, possibly extirpated at 8 sites, and 

extirpated at the remaining 16 sites 

within that ecoregion subsection in 

South Dakota (Service 2014, unpubl. 

geodatabase). 

In summary, South Dakota 

historically contained approximately 33 

percent of all known locations of the 

species rangewide. The current 

occupancy status of the Dakota skipper 

is unknown at 45 sites, and it is 

considered to be extirpated or possibly 

extirpated from at least 27 of the 86 

known sites in the State, although large 

areas of grasslands remain in South 

Dakota we don’t expect significant 

additional populations to be found if 

more surveys were conducted. 

Furthermore, downward trends and 

threats impacting populations at known 

sites are also likely occurring at 

potentially undiscovered sites. The 

species is considered to be present at 14 

of the 86 documented sites in the State. 

Twenty-six sites in South Dakota with 

previous Dakota skipper records were 

surveyed in 2012; the species was 

detected at nine of those sites; eight 

sites with no previous records for the 

species were surveyed during the 2012 

flight period, which resulted in the 

discovery of two nearby sites. Twentyeight sites in South Dakota with 

previous Dakota skipper records were 

surveyed in 2013; the species was 

detected at 9 of those sites (Service 

2014, unpubl. geodatabase). Ten 

additional sites within the species’ 

historical range were surveyed during 

the 2013 flight period, which resulted in 

no new Dakota skipper sites discovered 

(Service 2014, unpubl. geodatabase). 

The proportion of positive surveys at 

known sites has fluctuated over time; 

however, the 2012 and 2013 surveys 

had the lowest positive detection rate 

(35 percent and 32 percent, 

respectively) for the last 16 years (since 

1996)—much less than comparable 

survey years in South Dakota. 

Manitoba 

Manitoba historically contained 

approximately 14 percent (N = 37) of the 

known locations of the Dakota skipper 

rangewide. The Dakota skipper is 

considered present at 1 isolated site and 

28 sites split between 2 distinct 

complexes, 12 sites near Griswold and 

16 sites along Lake Manitoba. The 12 

sites near Griswold are located 

approximately 200 km (124 mi) 

southwest of the populations along Lake 

Manitoba (at 16 sites) and about 125 km 

(78 mi) northeast of the nearest 

population in Saskatchewan (Webster 

2003, pp. 5–6; Webster 2007, p. 4). The 

species is considered to be unknown at 

one site near Griswold where the 

species was detected in 2007 and 2011, 

but not during the most recent survey 

year (2012) (Rigney 2013a, p.117). The 

species is presumed extirpated or 

possibly extirpated from eight sites in 

Manitoba, including from the Tallgrass 

Prairie Preserve, where it has not been 


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found in the seven most recent survey 

years (Webster 2003, p. 5; Westwood et 

al. 2012, p. 1; Westwood 2007, pers. 

comm.; Hamel et al. 2013, pp. 8–16)— 

(the later surveys were focused on 

Poweshiek skipperlings, but other 

species were recorded), and one site that 

was converted to a flaxseed field 

(Webster 2003, p. 7). 

In 2007, researchers surveyed 16 sites 

for the Dakota skipper near Griswold, 

Manitoba (Webster 2007, p. 4), and 

found Dakota skippers at 14 of the 16 

sites; 12 of these represent new sites for 

the species in Manitoba (Webster 2007, 

p. 4). Four of these sites were 

resurveyed in subsequent years (2010, 

2011, and 2012)—the species is 

considered to be present at two sites, is 

unknown at one site due to a recent 

negative survey, and extirpated at the 

fourth site due to 3 consecutive negative 

survey years (Rigney 2013a, p. 117; 

Service 2014 unpublished database). 

The species is considered to be present 

at the remaining 10 sites that have not 

been surveyed since 2007. 

Until recently, population estimates 

and trends at the sites near Griswold in 

south west Manitoba have not been 

examined quantitatively; however, the 

population appears to be relatively 

stable at one site, may be declining at a 

second site, and is considered 

extirpated from two sites with repeated 

survey years. Numbers observed during 

searches at a site near Griswold in 2007 

did not appear to change appreciably 

since 2002 surveys, when the 

population was estimated (nonquantitatively) to be approximately 750 

individuals (Webster 2003, p. 5; Webster 

2007, p. 4). A total of 273 adults were 

observed during a 3.3-hour survey at the 

second site, where the population was 

estimated non-quantitatively to be about 

2,000 individuals (Webster 2007, p. 4). 

Survey methodology changes in the 

years since 2007 (two to five surveys per 

site per flight period in the timeframe 

2009–2013 compared to single site visits 

per year prior to 2008) have provided 

more rigorous population estimates at 

four Manitoba sites near Griswold and 

have shown a marked reduction in 

densities since 2002 or 2007 at three of 

the four sites (Rigney 2013a, p. 117). 

The Dakota skipper is present at two of 

the four sites near Griswold with 

repeated survey years. The estimated 

densities (mean number of individuals 

observed per hour) at one site remained 

at 1/hour in 2011 and 2012 and was 

approximately 30/hour in 2011 and 33/ 

hour in 2012 at a second site. The 

species is considered extirpated at one 

of these sites, because it was not 

detected during 2010, 2011, and 2012 

surveys. The status of the species is 

unknown at another site where the 

estimated numbers fell from 2/hour to 

zero detected in 2012 (Rigney 2013a, p. 

117). 

The Dakota skipper was first recorded 

near Winnipeg in 1933 and near Miniota 

in 1944 and then at two additional sites 

in the early 1990s. The species is 

considered to be extirpated or possibly 

extirpated at all of these sites (Service 

2014 unpubl. geodatabase). 

In 2002, the species was observed at 

19 sites near Lundar, within about 25 

km (16 mi) east of Lake Manitoba 

(Interlake region) (Webster 2003, p. 4); 

however, most of these sites have not 

been surveyed since. Similar to the 

Griswold sites, the survey methodology 

changes in years since 2007 (two to five 

surveys per site per flight period during 

2009–2013 compared to single site visits 

per year prior to 2008) have provided 

more rigorous population estimates at 

four Manitoba sites near Lake Manitoba 

(Interlake region) and have shown a 

marked reduction in densities since 

2002 or 2007 at two of the four sites 

(Rigney 2013a, p. 117). The species is 

considered present at two of four sites 

that have been surveyed since 2002 in 

this area; the species is considered 

extirpated from the other two sites due 

to three consecutive negative survey 

years (2010, 2011, and 2012) (Rigney 

2013a, p. 117). The mean number of 

individuals observed per hour at one 

site has declined from 2/hour in 2011 to 

1/hour in 2012 (Rigney 2013a, p. 117). 

The mean number per hour increased 

from approximately 1/hour to 6/hour at 

another site (Rigney 2013a, p. 117). The 

species is considered to be present at 

the remaining 14 Interlake sites that 

have not been resurveyed since 2002 

(Service 2014, unpublished database). 

Several additional areas were 

examined for potential Dakota skipper 

habitat in 2007, including areas east of 

Hwy 21, within the Lauder Sandhills 

Wildlife Management Area, north of 

Oak Lake and near Tilston, Sinclair, 

Cromer, and Brandon, as well as other 

locations. Most of the areas examined 

were under row crop agriculture, were 

heavily grazed, were dry scrub prairies, 

or were otherwise habitats unsuitable 

for Dakota skipper (Webster 2007, p. 6). 

In 2007, the areas near Brandon and the 

high ground within the wetland 

complexes near Oak Lake still contained 

potentially suitable habitat (Webster 

2007, p. 6). 

The nearest known extant (present) 

population of Dakota skippers in 

Manitoba is approximately 120 km (75 

mi) from the closest extant (present) 

population in North Dakota and about 

111 km (69 mi) from the closest 

Saskatchewan population. Britten and 

Glasford (2002, pp. 367, 372) suggested 

that Manitoba populations are 

genetically distinct from a group of 

populations in Minnesota and South 

Dakota, although populations in 

additional intervening locations should 

be sampled to confirm this hypothesis 

(Runquist 2012b, pers. comm.). 

Saskatchewan 

Saskatchewan historically contained 

approximately 5 percent (N=14) of all 

known records of Dakota skippers 

rangewide. In Saskatchewan, the Dakota 

skipper is restricted to undisturbed or 

lightly grazed, steep, south-facing hills 

near the Souris River (Webster 2007, p. 

ii). The Dakota skipper was first 

recorded south of Oxbow, 

Saskatchewan, in 2001 where three 

males were collected (Hooper 2003, p. 

124) on an ungrazed knoll within a 

patch of mixed-grass prairie that was 

approximately 1 ha (2 ac) in extent. 

Dakota skippers were found at three 

additional sites during 2002 surveys 

(Webster 2003, pp. 6–7). In 2007, 

researchers surveyed 16 sites in 

southeastern Saskatchewan and found 

Dakota skippers at 10 of these sites 

(including Oxbow); 8 of these represent 

new sites for the species in 

Saskatchewan (Webster 2007, p. i). 

During 2007 surveys, which were 

conducted late in the flight period, only 

a few individuals were observed at each 

site where the species was present 

(Webster 2007, p. ii). Nine of these sites 

where the species was found in 2007 

were surveyed along an approximate 50- 

km (31-mi) stretch of steep hillsides 

along the ridgeline north of Souris 

River; distances between sites range 

from 1 to 28 km (0.8 mi to 17 mi). We 

consider Dakota skipper to be present at 

all 14 sites in Saskatchewan, although 3 

of those sites have not been surveyed 

since 2002. The nearest known extant 

population of Dakota skippers in 

Saskatchewan is approximately 111 km 

(69 mi) from the closest extant (present) 

population in North Dakota and 200 km 

(125 mi) from the closest Manitoba 

population. 

Poweshiek Skipperling 

Species Description 

The Poweshiek skipperling (Oarisma 

poweshiek) is a member of the skipper 

family, Hesperiidae, and was first 

described by Parker (1870, pp. 271– 

272). Parker (1870, pp. 271–272) 

provided the original description of this 

species from his type series collected 

near Grinnell, Iowa. It was named for 

the county in which it was found 

(Poweshiek County), but it was 

misspelled, Powesheik, in the original 


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description. This spelling was retained 

by most early authorities (Lindsey 1922, 

p. 61; Holland 1931, p. 360). Miller and 

Brown (1981, p. 31) used the corrected 

spelling, Poweshiek, but then Miller and 

Ferris (1989, p. 31) changed it back in 

their supplement. Current usage is 

mixed, with many authorities retaining 

the original spelling (e.g., Miller 1992, 

p. 20), while others have opted for the 

corrected spelling (Layberry et al. 1998, 

p. 48; Opler et al. 1998, p. 363; 

Glassberg 1999, p. 167; Brock and 

Kaufman 2003, p. 306). Layberry et al. 

(1998, p. 48) state ‘‘. . . since it is a 

clear case of an original incorrect 

spelling it can be corrected [rule 32(c)ii 

of the International Code of Zoological 

Nomenclature].’’ 

Poweshiek skipperlings are small and 

slender-bodied, with a wingspan 

generally ranging from 2.3 to 3.0 cm (0.9 

to 1.2 in). The size of Poweshiek 

skipperlings appears to vary somewhat 

across their range (Royer and Marrone 

1992b, p. 3). North Dakota and South 

Dakota specimens tend to be slightly 

smaller than the 2.9 to 3.2 cm (1.1 to 1.3 

in) range given by Parker (1870) for the 

type specimens from Grinnell, Iowa 

(Royer and Marrone 1992b, p. 3). A 

sample of Richland County, North 

Dakota, specimens from Royer’s 

collection had an average wingspan of 

2.8 cm (1.1 in) for males and 3.0 cm (1.2 

in) for females. South Dakota specimens 

in Marrone’s collection had an average 

wingspan of 2.6 cm (1.0 in) for males 

and 2.7 cm (1.1 in) for females. The 

upper wing surface is dark brown with 

a band of orange along the leading edge 

of the forewing. Ground color of the 

lower surface is also dark brown, but the 

veins of all but the anal third of the 

hindwing are outlined in hoary white, 

giving an overall white appearance to 

the undersurface. 

The Poweshiek skipperling is most 

easily confused with the Garita 

skipperling (Oarisma garita), which can 

be distinguished from Poweshiek 

skipperling by their smaller size, 

quicker flight, and overall goldenbronze color (Royer and Marrone 1992b, 

p. 3). Another distinguishing feature is 

the color of the anal area of the ventral 

hindwing (orange in Garita; dark brown 

in Poweshiek). The Garita skipperling 

generally occurs west of Poweshiek 

skipperling range, although there are 

records of both species from two 

counties in southeastern North Dakota 

and two counties in northwestern 

Minnesota (Montana State University— 

Big Sky Institute 2012, Butterflies of 

North America http://

www.butterfliesandmoths.org, Accessed 

5/14/12; Minnesota Department of 

Natural Resources (DNR) 2012, Rare 

features database. Accessed 5/14/12). 

McAlpine (1972, pp. 85–92) described 

Poweshiek skipperling eggs as pale 

yellowish green, mushroom shaped 

with a flattened bottom, a slightly 

depressed micropyle (pore in the egg’s 

membrane through which the sperm 

enter) and smooth surfaced. They were 

0.8 millimeters (mm) (0.01 in) long, 0.7 

mm (0.03 in) wide and 0.5 mm (0.02 in) 

high. The overall color of the head and 

body of the larvae is pale grass-green, 

with a distinctive darker green middorsal stripe and seven cream-colored 

stripes on each side. First instars were 

1.8 mm (0.07 in) at hatching, and the 

lone 7th instar survivor was 23.6 mm 

(1.0 in) near the end of that stage. 

McAlpine did not have any observations 

past the 7th instar (the stage between 

successive molts, the first instar being 

between hatching and the first molt) 

(McAlpine 1972, pp. 85–93). 

General Life History 

Poweshiek skipperlings lay their eggs 

near the tips of leaf blades and 

overwinter as larvae on the host plants 

(Bureau of Endangered Resources in 

Swengel and Swengel 1999, p. 285, 

Borkin 2000, p. 7). Poweshiek 

skipperlings have also been documented 

laying eggs on the entire length of grass 

leaf blades and on low-growing 

deciduous foliage (Dupont 2013, p. 133). 

McAlpine (1972, pp. 85–92) described 

the various life-history stages of 

Poweshiek skipperling, and recent 

studies of captive Poweshiek 

skipperlings at the Minnesota Zoo 

provide additional information 

(Runquist 2013, pers. comm.). McAlpine 

(1972, pp. 85–93) observed hatching of 

larval Poweshiek skipperling after about 

9 days. McAlpine’s records were 

incomplete, and he did not have any 

observations past the 7th instar, but he 

believed that there should have been 

one or two additional instars, followed 

by the chrysalis (pupa) and then the 

imago (adult) stages (McAlpine 1972, 

pp. 85–93). Captive Poweshiek 

skipperling eggs hatched 8 to 9 days 

after oviposition (Runquist 2013, pers. 

comm.). After hatching, Poweshiek 

skipperling larvae crawl out near the tip 

of grasses and may remain stationary, 

with their head usually pointing 

downward (McAlpine 1972, pp. 88–92). 

Unlike Dakota skippers, Poweshiek 

skipperling do not form shelters 

underground (McAlpine 1972, pp. 88– 

92; Borkin 1995, p. 9; Borkin 2008, pers. 

comm.), instead the larvae overwinter 

up on the blades of grasses and on the 

stem near the base of the plant (Borkin 

2008, pers. comm.; Dana 2008, pers. 

comm.). Borkin (2008, pers. comm.) 

observed larvae moving to the tips of 

grass blades to feed on the outer and 

thinner edges of the blades, with later 

movement down and among blades. 

Mature Poweshiek skipperling 

caterpillars reared in captivity ranged in 

size from approximately 22 to 25 mm 

(0.9 to 1 inch) in length just prior to 

pupation (Runquist 2013, pers. comm.). 

Food and Water 

For the Poweshiek skipperling, nectar 

plants vary across its geographic range. 

Smooth ox-eye (Heliopsis helianthoides) 

and purple coneflower were noted as 

the frequently visited nectar plants in 

Iowa, Minnesota, and North Dakota 

(Swengel and Swengel 1999, p. 280). 

Other nectar species used were stiff 

tickseed (Coreopsis palmata), blackeyed Susan, and palespike lobelia 

(Swengel and Swengel 1999, p. 280). On 

drier prairie habitats in Iowa and 

Minnesota, purple coneflower is used 

almost exclusively, and the emergence 

of the adults corresponds closely to the 

early maturity of this species’ disk 

florets (Selby 2005, p. 5). On the wetter 

prairie habitats of Canada and the fen 

habitats of Michigan, favored nectar 

plants are black-eyed Susan, palespike 

lobelia, sticky tofieldia (Triantha 

glutinosa), and shrubby cinquefoil 

(Dasiphora fruticosa ssp. floribunda) 

(Nielsen 1970, p. 46; Holzman 1972, p. 

111; Catling and Lafontaine 1986, p. 65; 

Bess 1988, p. 13; Summerville and 

Clampitt 1999, p. 231). Recent studies in 

Manitoba indicate that the most 

frequently used nectar plants are blackeyed Susan, upland white aster, and 

self-heal (Prunella vulgaris) (Dupont 

2013, pp. 70–71). In addition to 

nutrition, the nectar of flowering forbs 

provides water for Poweshiek 

skipperling, which is necessary to avoid 

desiccation during flight activity (Dana 

2013, pers. comm.). 

Until recently, the larval food plant 

was presumed to be elliptic spikerush 

(Eleocharis elliptica) or sedges, but this 

was based on limited observations, 

primarily from the Michigan 

populations (e.g., Holzman 1972, p. 

113). More recent observations show 

that the preferred larval food plant for 

some populations of Poweshiek 

skipperling is prairie dropseed (Borkin 

1995, p. 6); larvae have also been 

observed feeding on little bluestem 

(Schizachyrium scoparium) (Borkin 

1995, pp. 5–6) and sideoats grama 

(Bouteloua curtipendula) (Dana 2005a, 

pers. comm.). Poweshiek skipperling 

larvae have been observed feeding on 

Carex sp. (Borkin 1994, p. 6; Borkin 

1996, p. 2), although not through the 

entire larval development (Borkin 2014, 

pers. comm.). Poweshiek skipperling 


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have been observed laying eggs 

(ovipositing) on mat muhly 

(Muhlenbergia richardsonis) (Cuthrell 

2012a, pers. comm.), a grass in 

Michigan’s prairie fens (Penskar and 

Higman 1999, p. 1). Captive-reared 

caterpillars fed most successfully on 

prairie dropseed, and older caterpillars 

(late 2-day instar and older) successfully 

fed on little bluestem, big bluestem, and 

side-oats gramma (Runquist 2013, pers. 

comm.). One post-diapause Poweshiek 

skipperling was successfully reared to 

adulthood on Pennsylvania sedge 

(Carex pensylvanica) (Runquist 2013, 

pers. comm.). 

In southwestern Minnesota dry hill 

prairies, Poweshiek skipperling 

oviposition was observed on prairie 

dropseed, little bluestem, big bluestem, 

porcupine grass, and a couple 

unidentified species; a larva was 

observed feeding on sideoats grama 

(Dana 2005a, pers. comm.). Poweshiek 

skipperlings were observed to oviposit 

on big bluestem in Wisconsin (Borkin 

2012a, pers. comm.), although 

indiscriminate oviposition on 

unsuitable larval plants has been 

observed during high summer 

temperatures (Borkin 1995, p. 6). Borkin 

(1995, p. 4) also observed oviposition on 

an unidentified sedge (Eleocharis sp.), 

but only 2 eggs were found on the sedge 

in comparison to more than 100 eggs 

found on prairie dropseed. In Manitoba, 

Poweshiek skipperlings were observed 

ovipositing on big bluestem, white 

sweet clover, an unidentified goldenrod 

(Solidago spp.), and juvenile bur oak 

(Quercus macrocarpa) leaves (Dupont 

2013, p. 73). Poweshiek skipperlings 

have also been documented laying eggs 

on the entire length of grass leaf blades, 

including the tips, and on low-growing 

deciduous foliage (Dupont 2013, p. 133). 

Dana (2013, pers. comm.) noted that 

larvae seem to begin feeding at a very 

fine, threadlike blade tip and females 

placed eggs on fine blade tips of grasses 

during some observed ovipositions. 

Consistent with field observations of 

female oviposition on fine blades of 

grass, captive-reared caterpillars (early 

instars) preferred feeding on finer leaf 

blades (Runquist 2013, pers. comm.). 

Dispersal 

Poweshiek skipperlings are also not 

known to disperse widely; the species 

was evaluated among 291 butterfly 

species in Canada as having relatively 

low mobility; experts estimated 

Poweshiek skipperling to have a mean 

mobility of 2 (standard deviation = 1.4) 

on a scale of 0 (sedentary) to 10 (highly 

mobile) (Burke et al. 2011, p. 2279; 

Fitzsimmons 2012, pers. comm.). A 

mark–recapture study was conducted in 

Manitoba in 2008 and 2009; however, 

only 2 of the 56 marked individuals in 

2008 were recaptured and none of the 

16 marked individuals in 2009 were 

recaptured, so available data are 

insufficient to examine within and 

between site dispersal (Dupont 2013, 

pp. 68–70). After 2 days, the two 

recaptured individuals were within 50 

m (165 ft) of their initial capture 

location (Dupont 2013, p. 69). 

Besides this study in Manitoba, which 

had too few recaptures to make any 

statistically significant conclusions, we 

are unaware of any other studies that 

documented the dispersal distance of 

the species. Therefore, we used the 

Dakota skipper as a surrogate species to 

estimate the maximum dispersal 

distance of Poweshiek skipperlings and 

verified our assumptions with expert 

review. In a mark–recapture study, 

average adult movements of Dakota 

skippers were less than 300 meters (m) 

(984 feet (ft)) during a period of 3–7 

days; marked adults crossed less than 

200 m (656 ft) of unsuitable habitat 

between two prairie patches and moved 

along ridges more frequently than across 

valleys (Dana 1991, pp. 38–40). Dana 

(1997, p. 5) later observed reduced 

movement rates across a small valley 

dominated by exotic grasses with roads 

and crop fields compared with 

movements in adjacent widespread 

prairie habitat. Roads and crop fields 

were suspected as impediments for 

movement among prairie patches along 

two sites of the main valley (Dana 1997, 

p. 5), although movements beyond the 

study area were beyond the scope of the 

1997 mark–recapture study (Dana 2013, 

pers. comm.). Skadsen (1999, p. 2) 

reported possible movement of Dakota 

skippers in 1998 from a known 

population at least 800 m (2,625 ft) 

away to a site with an unusually heavy 

growth of purple coneflower; he had not 

found Dakota skippers in three previous 

years when coneflower production was 

sparse. 

Based on expert opinion, a maximum 

dispersal distance of 1.6 km (1.0 mi) 

was estimated to be a reasonable and 

likely distance for male Poweshiek 

skipperling to travel between patches of 

prairie habitat separated by structurally 

similar habitats (e.g., perennial 

grasslands but not necessarily native 

prairie) (Westwood 2012a and 2012b, 

pers. comm.; Dana 2012b, pers. comm.). 

The species, however, will not likely 

disperse across habitat that is not 

structurally similar to native prairies, 

such as certain types of row crops or 

anywhere not dominated by grasses 

(Westwood 2012a and 2012b, pers. 

comm.; Dana 2012b, pers. comm.). In 

Manitoba, Poweshiek skipperling have 

been observed avoiding dispersal over 

short distances, even to suitable habitat, 

if a barrier such as a road exists between 

suitable prairie habitat and nectar 

sources (Westwood et al. 2012, p. 18). 

Since experts estimated Dakota 

skippers to have a mean mobility of 3.5 

(standard deviation = 0.7) on a scale of 

0 (sedentary) to 10 (highly mobile), 

which is higher than the estimate for the 

Poweshiek skipperling (mean mobility 

of 2) (Burke et al. 2011, p. 2279; 

Fitzsimmons 2012, pers. comm.), we 

used the estimated dispersal distance of 

the Dakota skipper, approximately 1 km 

(0.6 mi) (Cochrane and Delphey 2002, p. 

6), which is more conservative than the 

1.6 km (1.0 mi) estimated for the 

Poweshiek skipperling by expert 

opinion (Westwood 2012b, pers. comm., 

Dana 2012b, pers. comm.). One 

kilometer is a reasonable maximum 

dispersal distance, since no data 

documents the species that document a 

greater distance travelled. 

In summary, using the best 

information available, dispersal of 

Poweshiek skipperling is very limited 

due in part to its short adult life span 

and single annual flight. Therefore, the 

species’ extirpation from a site is likely 

permanent unless it is within about 1 

km (0.6 mi) of a site that generates a 

sufficient number of emigrants or is 

artificially reintroduced to a site; 

however, the capability to propagate the 

Poweshiek skipperling is currently 

lacking. 

Habitat 

Poweshiek skipperling habitats 

include prairie fens, grassy lake and 

stream margins, moist meadows, sedge 

meadow, and wet-to-dry prairie. 

McCabe and Post (McCabe and Post 

1977, pp. 36–38) describe the species’ 

habitat in North Dakota as ‘‘. . . high 

dry prairie and low, moist prairie 

stretches as well as old fields and 

meadows.’’ Royer and Marrone (1992b, 

p. 12) describe Poweshiek skipperling 

habitat in North Dakota and South 

Dakota as moist ground in undisturbed 

native tallgrass prairies. Poweshiek 

skipperling habitat throughout Iowa and 

Minnesota is described as both ‘‘high 

dry’’ and ‘‘low wet’’ prairie (McCabe 

and Post 1977, pp. 36–38). The only 

documented Illinois record was 

associated with high rolling prairie 

(Dodge 1872, p. 218); the only 

documented Indiana record was from 

marshy lakeshores and wetlands 

(Blatchley 1891, p. 398; Shull 1987, p. 

29). 

Southern dry prairies in Minnesota 

are described as having sparse shrub 

cover (less than 5 percent) composed 

primarily of leadplant, with prairie rose, 


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wormwood sage, or smooth sumac 

present and few, if any, trees (Minnesota 

DNR 2012a, p. 1). Southern mesic 

prairies also have sparse shrubs (5–25 

percent cover) consisting of leadplant 

and prairie rose with occasional 

wolfberry (Symphoricarpos 

occidentalis) and few, if any, trees 

(Minnesota DNR 2012b, p. 1). 

The disjunct populations of 

Poweshiek skipperlings in Michigan 

have more narrowly defined habitat 

preferences, variously described as wet 

marshy meadows (Holzman 1972, p. 

114), bog fen meadows or carrs (Shuey 

1985, p. 181), sedge fens (Bess 1988, p. 

13), and prairie fens (Michigan Natural 

Features Inventory 2011, unpubl. data; 

Michigan Natural Features Inventory 

2012, unpubl. data); prairie fen is the 

currently accepted name for this habitat 

type. Bess (1988, p. 13) found the 

species primarily in the drier portions of 

Liberty Fen, Jackson County, dominated 

by ‘‘low sedges’’ and an abundance of 

nectar sources. Summerville and 

Clampitt (1999, p. 231) noted that the 

population was concentrated in areas 

dominated by spikerush and that only 

10–15 percent of the fen area was 

occupied despite the abundance of 

nectar sources throughout. Poweshiek 

skipperling have been described as 

occupying peat domes within larger 

prairie fen complexes in areas either 

dominated by mat muhly or prairie 

dropseed (Cuthrell 2013a, pers. comm.). 

A few prairie fens in Michigan also 

contain other rare butterflies, such as 

Mitchell’s satyr and swamp metalmark 

(Cuthrell 2013a, pers. comm.). 

Poweshiek skipperling populations in 

Wisconsin are also disjunct from the 

population to the west and are 

associated with areas that contain 

intermixed wet prairie, wet-mesic, and 

dry-mesic prairie habitats (Borkin 1995, 

p. 6; Swengel 2013, pers. comm.). The 

dry-mesic habitats in the Scuppernong 

Prairie contain ‘‘extensive patches of 

prairie dropseed and little bluestem 

grasses’’ (Borkin 1995, p. 7). Survival in 

wetter areas, which tend to burn cooler 

and less completely, coupled with low 

recolonization rates, or the 

disproportionate loss of wet versus dry 

prairie could give the false impression 

that the wet areas were their preferred 

habitat (Borkin 1995, p. 7). Puchyan 

Prairie consists of wet-mesic prairie that 

grades lower into sedge meadow (WI 

DNR Web site http://dnr.wi.gov/topic/

Lands/naturalareas/

index.asp?SNA=172; Swengel 2013, 

pers. comm.) and adult Poweshiek 

Skipperlings have been observed in wet 

prairie there, although it is not known 

if these areas function as successful 

larval habitat (Swengel 2013, pers. 

comm.). 

Like the Dakota skipper, it has been 

hypothesized that Poweshiek 

skipperling larvae may be vulnerable to 

desiccation during dry summer months 

(Borkin 2012a, pers. comm.) and require 

movement of shallow groundwater to 

the soil surface or wet low areas to 

provide relief from high summer 

temperatures or dry conditions (Royer et 

al. 2008, pp. 2, 16; Borkin 2012a, pers. 

comm.). Humidity may also be an 

essential factor to larval survival during 

winter months since the larvae cannot 

take in water during that time and 

depend on humid air to minimize water 

loss through respiration (Dana 2013, 

pers. comm.). 

Royer (2008, pp. 14–15) measured 

microclimatological (climate in a small 

space, such as at or near the soil surface) 

levels within ‘‘larval nesting zones’’ (0 

to 2 cm above the soil surface) at six 

known Poweshiek skipperling sites, and 

found an acceptable rangewide seasonal 

(summer) mean temperature range of 18 

to 21 °C (64 to 70 °F), rangewide 

seasonal mean dew point ranging from 

14 to 17 °C (57 to 63 °F), and rangewide 

seasonal mean relative humidity 

between 73 and 85 percent. Royer 

(2008) examined only occupied areas for 

these parameters; therefore, the 

statistical and biological significance of 

these edaphic variables cannot be 

determined from his study. 

Canadian populations of Poweshiek 

skipperlings are restricted to a single 

2,300-ha (5,683-ac) area in southeastern 

Manitoba (COSEWIC 2003, p. 5). The 

wet to mesic tallgrass prairie in this area 

is characterized by low relief (1–2 m (3– 

7 ft)), with alternating lower, wetter 

areas and higher, drier prairie; 

Poweshiek skipperlings tend to be 

concentrated on or near the edge of the 

higher, drier prairie (COSEWIC 2003, p. 

8). Spikerush is frequent in the wetter 

areas, and prairie dropseed, black-eyed 

Susan, and palespike lobelia are 

frequent in the drier areas (COSEWIC 

2003, pp. 7–8). The wet-mesic tallgrass 

prairies in Manitoba vary in size and 

occur along bluffs of Bur oak and 

trembling aspen (Populus tremuloides 

Michx.) (Catling and Lafontaine 1986; 

Dupont 2013, p. 17). Little bluestem, big 

bluestem, and Indian grass were the 

three most common grasses in managed 

study plots in Manitoba (Dupont 2013, 

p. 85). Plant species generally associated 

with upland, drier portions of the mesic 

tallgrass prairies in Manitoba include: 

Big bluestem, pale-spike lobelia, prairie 

dropseed, mountain death camas, stiff 

goldenrod, black-eyed Susan, and 

meadow blazing-star (Environment 

Canada 2012, p. 6). In lower, wetter 

prairies with Poweshiek skipperlings, 

the following species are listed as often 

seen: Willow (Salix spp.), sedges (Carex 

spp.), rushes (Juncus spp.), groundsels 

(Pakera spp.), tufted hairgrass, creeping 

bentgrass (Agrostis stolonifera), mat 

muhly, elliptic spike-rush, fourflowered yellow loosestrife (Lysimachia 

quadriflora), and common self-heal 

(Environment Canada 2012, p. 6). Most 

of these plants were also commonly 

observed in study plots surveyed in 

2008–2009 (Dupont 2013, p. 86). The 

soils where the Poweshiek skipperling 

occurs in Manitoba are described as 

shallow, rocky, and highly calcareous 

(Westwood and Borkowsky 2004 in 

Dupont 2013, p. 19). 

Prairie fen habitat soils in Michigan 

are described as saturated organic soils 

(sedge peat and wood peat) and marl, a 

calcium carbonate (CaCO3) precipitate 

(MINFI Web site accessed August 3, 

2012). In other States, soil textures in 

Poweshiek skipperling habitats are 

classified as loam, sandy loam, or loamy 

sand (Royer et al. 2008, pp. 3, 10); soils 

in moraine deposits are described as 

gravelly, except the deposits associated 

with glacial lakes. 

Population Distribution and Occupancy 

The Poweshiek skipperling is 

historically known from eight States, 

ranging widely over the native wetmesic to dry tallgrass prairies from 

eastern North and South Dakota (Royer 

and Marrone 1992b, pp. 4–5) through 

Iowa (Nekola and Schlicht 2007, p. 7) 

and Minnesota (Minnesota DNR, 

Division of Ecological Resources, 

unpubl. data), with occurrences also 

documented in northern Illinois (Dodge 

1872, p. 218), Indiana (Blatchley 1891, 

p. 898), Michigan (Holzman 1972, p. 

111; McAlpine 1972, p. 83), and 

Wisconsin (Borkin 2011, in litt.; Selby 

2010, p. 22). The relatively recent 

discovery of Poweshiek skipperling 

populations in the Canadian province of 

Manitoba further extends its known 

historical northern distribution 

(Westwood 2010, pp. 7–22; Dupont 

2010, pers. comm.). Additional 

historical accounts of Poweshiek 

skipperling from the States of Montana, 

Colorado, and Nebraska are likely 

misidentifications of its western 

congener, the Garita skipperling. 

Once common and abundant 

throughout native prairies in eight 

States and at least one Canadian 

province, the Poweshiek skipperling 

and its habitat have experienced 

significant declines. The species is 

considered to be present at a few native 

prairie remnants in two States and one 

location in Manitoba, Canada. The 

species is presumed extirpated from 


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Illinois and Indiana, and the status of 

the species is uncertain in four of the six 

States with relatively recent records 

(within the last 20 years). The historical 

distribution of Poweshiek skipperling 

may never be precisely known because 

‘‘much of tallgrass prairie was 

extirpated prior to extensive ecological 

study’’ (Steinauer and Collins 1994, p. 

42), such as butterfly surveys. 

Destruction of tallgrass and mixed-grass 

prairie began in 1830 (Sampson and 

Knopf 1994, p. 418), but significant 

documentation of the ecosystem’s 

butterfly fauna did not begin until about 

1960. Therefore, most of the decline of 

the Poweshiek skipperling probably 

went unrecorded. Poweshiek 

skipperling dispersal is very limited due 

in part to its short adult life span and 

single annual flight. Therefore, the 

species’ extirpation from a site is likely 

permanent unless it is within about 1 

km (0.6 mi) of a site that generates a 

sufficient number of emigrants or is 

artificially reintroduced to a site. 

Recent survey data indicate that 

Poweshiek skipperling has declined to 

zero or to undetectable levels at 96 

percent of sites where it has ever been 

recorded. Until about 2003, Poweshiek 

skipperling was regarded as the most 

frequently and reliably encountered 

prairie-obligate skipper butterfly in 

Minnesota, which contains 

approximately 48 percent of all known 

Poweshiek skipperling locations 

rangewide. Numbers and distribution 

dropped dramatically in subsequent 

years, however, and the species was not 

seen in Minnesota from 2007 through 

2012. Two individuals were observed at 

one site in 2013 (Weber 2014, in litt.; 

Dana 2014, pers. comm.). In Iowa, the 

Poweshiek skipperling was found at 2 of 

33 sites with previous records surveyed 

in 2007; the species was last observed 

at one site in 2008. Iowa contains about 

14 percent of documented sites 

rangewide. Unidentified threats to the 

species have acted to extirpate or 

sharply diminish populations at all or 

the vast majority of sites in Iowa and 

Minnesota (Dana 2008, p. 16; Selby 

2010, p. 7). 

South Dakota historically contained 

about 23 percent of the rangewide sites 

with documented presence of 

Poweshiek skipperling, although recent 

surveys in that State also suggest an 

emergent and mysterious decline. The 

species was last observed in South 

Dakota in 2008, at three sites. Surveys 

conducted in 2009–2013 flight seasons 

in South Dakota resulted in zero 

detections of the species. North Dakota 

historically contained about six percent 

of the rangewide sites with documented 

presence of Poweshiek skipperling; the 

species was last observed in North 

Dakota in 2001. Survey efforts in North 

Dakota have been minimal between 

1998 and 2011, but surveys conducted 

in 1997 documented more than 10 

Poweshiek skipperlings at 1 site; 6 

individuals were counted at 1 site, and 

0 were detected at 6 other sites. Surveys 

conducted during the 2012 and 2013 

flight seasons in North Dakota resulted 

in zero detections of the species. 

Seven Michigan sites were recently 

ranked as having good or better 

‘‘viability,’’ a habitat-based element 

occurrence rank assigned by the 

Michigan Natural Features Inventory 

(2011); however, the number of 

individuals observed at a few of those 

sites has declined in recent years, and 

the species is presumed extirpated from 

one of those sites. Currently, four of the 

ten extant occurrences of Poweshiek 

skipperling in Michigan are considered 

to have good or better viability 

(Michigan Natural Features Inventory 

(2011, unpubl. data). Each of those faces 

threats of at least low to moderate 

magnitude, and the State contains only 

about 6 percent of all known historical 

Poweshiek skipperling records. One 

population of Poweshiek skipperlings in 

Wisconsin had fairly consistent 

numbers observed over the last 5 years 

(17 to 63 individuals counted using 

modified Pollard transect covering 15 ac 

(6 ha) in approximately 40 minutes), but 

the species was not observed in 2013 

surveys. One population in Manitoba 

has fairly consistent numbers (typically 

hundreds of individuals observed each 

year). To summarize, of the 298 

documented sites, there are 12 sites 

where we consider the Poweshiek 

skipperling to be present, 111 sites with 

unknown status, 96 possibly extirpated 

sites, and 79 where we consider the 

species to be extirpated (Table 2). The 

distribution and status of Poweshiek 

skipperling in each State of known 

historical or extant occurrence are 

described in detail below. 

TABLE 2—NUMBER OF HISTORICALLY DOCUMENTED POWESHIEK SKIPPERLING SITES WITHIN EACH STATE AND THE NUMBER OF SITES WHERE THE SPECIES IS THOUGHT TO BE PRESENT, UNKNOWN, POSSIBLY EXTIRPATED, OR EXTIRPATED

State 

State’s 

percentage 

of the total 

number of 

historical 

sites 

Present Unknown Possibly 

extirpated Extirpated Total 

Illinois ............................................................................... 1.3 .................... .................... .................... 4 4 

Indiana ............................................................................. 0.3 .................... .................... .................... 1 1 

Iowa .................................................................................. 13.8 .................... 4 24 13 41 

Michigan ........................................................................... 5.7 9 2 .................... 6 17 

Minnesota ......................................................................... 48.3 1 58 64 21 144 

North Dakota .................................................................... 5.7 .................... 8 6 3 17 

South Dakota ................................................................... 23.2 .................... 36 2 31 69 

Wisconsin ......................................................................... 1.3 1 3 .................... .................... 4 

Manitoba .......................................................................... 0.3 1 .................... .................... .................... 1 

Total Number of Historically Documented Sites ...... .................... 12 111 96 79 298 

Percent of the Total Number of Historical Sites by Occupancy ........................................................................ .................... 4% 37% 32% 27% ....................

Illinois 

The Poweshiek skipperling 

historically occurred in Illinois, 

although only one historical occurrence 

is supported (Table 2). In the early 

1870s, Dodge (1872, p. 218) reported 

abundant Poweshiek skipperling 

occupying ‘‘the high rolling prairie that 

forms the divide between the Illinois 


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and Rock rivers’’ in Bureau County, 

Illinois. In addition to Bureau County, 

the Web site Butterflies and Moths of 

North America lists Poweshiek 

skipperling historical occurrences for 

Lake and Mason Counties, which were 

submitted to the Web site before the 

date field was required, so a default date 

of January 1, 1950, was assigned, which 

is outside of the typical flight period 

(http://www.butterfliesandmoths.org/

species/Oarisma-poweshiek; accessed 

August 16, 2012). The Web site 

maintains a verifiable database on 

species occurrences, but there is no 

accessible supporting data for the Lake 

and Mason Counties records (Lundh 

2012, pers. comm.). One additional 

record, housed at University of 

Wisconsin–Oshkosh, was collected in 

DuPage County in 1968 and was 

recently identified as a Poweshiek 

skipperling. The location where the 

specimen was collected has since been 

converted and is no longer a prairie, and 

it is presumed that the species is 

extirpated from that location (Borkin 

2014, pers. comm.). Poweshiek 

skipperling is, therefore, presumed to be 

extirpated from Illinois. 

Indiana 

There is one supported historical 

occurrence of Poweshiek skipperlings in 

Indiana (Table 2). Blatchley (1891, p. 

898) reported small numbers of 

Poweshiek skipperlings near Whiting, 

Indiana; Shull (1987, p. 49) expressed 

confidence that this record is authentic. 

The Poweshiek skipperling is 

considered extirpated from Indiana. 

Iowa 

Iowa historically contained 

approximately 14 percent (N=41) of all 

known records of Poweshiek 

skipperlings rangewide (Table 2). The 

Poweshiek skipperling was historically 

known to occur at 38 sites in 13 

counties in Iowa (Nekola 1995, p. 8; 

Saunders 1995, pp. 27–28; Selby 2005, 

p. 18; Nekola and Schlicht 2007, p. 7; 

Selby 2010, p. 6); however, this number 

may vary slightly (up to 41 sites) 

depending on how one divides sites 

along the Little Sioux River in the 

Freda-Cayler area (Selby 2012a, pers. 

comm.). Early reports from Parker (1870, 

p. 271) described Poweshiek skipperling 

as abundant on a prairie slope at 

Grinnell, Iowa, while Lindsey (1917, p. 

352; 1920, p. 320) noted additional rare 

occurrences in Story, Dickinson, 

Poweshiek, and Woodbury Counties, 

Iowa—among these, habitat has long 

since been destroyed in all but 

Dickinson County. 

In 1993–1994, 65 sites were surveyed 

in 17 counties where Dakota skipper or 

Poweshiek skipperling had been 

previously recorded or where prairie 

and butterfly surveys or infra-red 

photography suggested the presence of 

Poweshiek skipperling habitat 

(Saunders 1995, pp. 7–8). Among the 65 

sites surveyed, Poweshiek skipperlings 

were found at 29 sites in 10 counties 

(Saunders 1995, p. 27). In 2000, 

Poweshiek skipperlings were found at 

six sites surveyed in and near Cayler 

Prairie and Freda Haffner Kettlehole 

State preserves in Dickinson County 

(Selby 2000, p. 19). Followup surveys of 

this complex in 2004, 2005, and 2007, 

however, produced no confirmed 

sightings (Selby 2010, p. 6). Extensive 

surveys were conducted in 2007, and 

included 32 of the 38 sites in the State 

with post-1990 records (Selby 2008, pp. 

4, 6). Poweshiek skipperlings were 

found at 2 of the 38 sites surveyed— 

Hoffman Prairie State Preserve in Cerro 

Gordo County and Highway 60 Railroad 

Prairie in Osceola County (Selby 2008, 

pp. 6–7). Five of the six sites not 

included in the 2007 surveys had very 

little quality prairie (Selby 2012a, pers. 

comm.). Supplementary surveys 

conducted further west along U.S. 

Highway 18 in Hancock County also 

produced no confirmed sightings (Selby 

2010, p. 7). No surveys were conducted 

at previously known Poweshiek 

skipperling sites in the State during the 

2012 flight season. No Poweshiek 

skipperlings were observed in surveys 

in 2013 at two sites with relatively 

recent records of the species (2005 and 

2008) (Olsen 2013, p. 2). 

The Poweshiek skipperling is 

presumed extirpated or possibly 

extirpated from all but four of the 

known sites in Iowa. The status of the 

Poweshiek skipperling is unknown at 

four sites: Highway 60 Railroad Prairie, 

Floete Prairie in Dickinson County, 

Florenceville Prairie, and Hayden 

Prairie in Howard County. There have 

been no surveys at Highway 60 Railroad 

Prairie since the species was observed 

there in 2007 (Selby 2012a, pers. 

comm.). The last observation of 

Poweshiek skipperling at Floete Prairie 

was in 1994, and the habitat ‘‘did not 

appear to be very good quality’’ in 2007, 

although the site was not surveyed for 

butterflies that year (Selby 2012a, pers. 

comm.) or in subsequent years. The 

Poweshiek skipperling was last 

observed at the Florenceville Prairie in 

1994 (Saunders 1995, p. 27), but not 

during the 2007 survey year (Selby 

2010, pp. 8–11). The species was last 

observed at Hayden Prairie in 2005, but 

not during surveys conducted in 2007 

(Selby 2010, p. 10) or 2013 (Olsen 2013, 

p. 2). Four Poweshiek skipperlings were 

found at Hoffman Prairie in Cerro Gordo 

County in 2008 (Selby 2009b, p. 3), but 

none were found during surveys in 2009 

(Selby 2009b, p. 7) and 2010 (Selby 

2010, p. 7). We initially assigned an 

unknown status to the Hoffman Prairie 

site because the species had not been 

seen in the 2009 and 2010 survey years; 

however, Selby believes that the species 

may be extirpated from this site (Selby 

2012a, pers. comm.), so we assigned a 

status of extirpated to this site, which 

was confirmed with negative surveys in 

the 2013 flight season (Olsen 2013, p. 2). 

To summarize, the Poweshiek 

skipperling was historically 

documented in 41 sites in Iowa. The 

species occupancy is unknown at 4 of 

those sites, and the species is 

considered to be extirpated or possibly 

extirpated at 13 and 24 sites, 

respectively (Table 2). The species is not 

considered to be present at any of the 

sites in Iowa. 

Michigan 

Michigan historically contained 

approximately 6 percent (N=17) of all 

known records of Poweshiek 

skipperlings rangewide (Table 2). 

Poweshiek skipperling has been 

historically documented at 17 sites in 6 

counties in Michigan. The species was 

first recorded in Michigan in 1893 at 

Lamberton Lake near Grand Rapids in 

Kent County (Holzman 1972, p. 111) 

and then at nearby Button Lake Fen 

(also known as Emerald Lake Fen) in 

1944 (McAlpine 1972, p. 83). Shrubs 

have invaded both sites, however, and 

no Poweshiek skipperlings have been 

found at either of these two western 

Michigan sites since 1944 and 1968, 

respectively (Michigan Natural Features 

Inventory 2011, unpubl. data). Holzman 

(1972, p. 111) documented Poweshiek 

skipperling in Oakland County in 1970, 

and the species has since been found at 

a total of 15 locations in eastern 

Michigan. 

The Poweshiek skipperling is 

currently considered to be present at 

nine sites (Table 2) in four counties in 

Michigan: Jackson, Lenawee, Oakland, 

and Washtenaw. The species has been 

observed recently (2008–2013) at most 

of those sites, except at the Liberty Bowl 

Fen in Jackson County, which has not 

been surveyed since one individual was 

observed in 1996. The status of the 

species is unknown at two sites; Bullard 

Lake in Livingston County, where 

Poweshiek skipperlings were last seen 

in 2007, but not in subsequent surveys 

in 2008 and 2009 (Cuthrell 2012a, pers. 

comm.), and Liberty Fen (Grand River 

Fen) in Jackson County, where 

Poweshiek skipperlings were observed 

in 2012 but not in 2013 surveys 


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(Cuthrell 2013, pers. comm.). The 

species is presumed extirpated from six 

sites including the only two sites in 

Kent County and three sites in Oakland 

County: Rattalee Road, Fenton Road, 

and Rattalee Lake Fen (Call C Burr 

Preserve) fens. The species has not been 

observed at the Rattalee Road and 

Fenton Road sites since 1970 and 1973, 

respectively (Michigan Natural Features 

Inventory 2011, unpubl. data). Four 

Poweshiek skipperlings were seen in 

2009 at the Rattalee Lake Fen (Calla C 

Burr Preserve), but none were observed 

during surveys conducted in 2010, 

2011, and 2012 (Cuthrell 2012a, pers. 

comm.; Michigan Natural Features 

Inventory 2011, unpubl. data). The 

Michigan Natural Features Inventory 

(MNFI) also considers the two sites in 

Kent County to be extirpated due to 

habitat loss and destruction, Lamberton 

Lake and Button Lake (also known as 

Emerald Lake); the species has not been 

observed at either site since 1968 and 

1944, respectively. The species is 

presumed to be extirpated at Whalen 

Lake Fen in Livingston County, where 

the species has not been observed since 

1998 despite three subsequent years of 

surveys (Michigan Natural Features 

Inventory 2011, unpubl. data). 

Four of Michigan’s nine extant 

(present) Poweshiek skipperling 

occurrences were recently considered to 

have at least good viability (Michigan 

Natural Features Inventory 2011, 

unpubl. data); however, 2013 survey 

results have put the viability in 

question. Three of these sites, Buckhorn 

Lake also known as Big Valley), Brandt 

Road Fen (also known as Holly Fen) and 

Long Lake Fen, are within 20 km (12 mi) 

of one another in Oakland County; all 

with relatively large numbers (61–389) 

of the species recorded in 2010–2012 

surveys (Michigan Natural Features 

Inventory 2011, unpubl. data; Cuthrell 

2012a, pers. comm.). In 2013, however, 

2 individuals (0.008/hr.) were recorded 

at Buckhorn Lake, which was down 

from 84 individuals (0.35/hr.) recorded 

the previous survey year (2012) with 

similar effort, and 53 individuals (0.33/ 

hr.) were recorded at Brandt Road in 

2013, down from 71 individuals (0.59/ 

hr.) recorded the previous survey year 

(2012) with similar effort. The largest 

extant (present) Poweshiek skipperling 

population in Michigan may be at Long 

Lake Fen, where 25 individuals (0.2/hr.) 

were counted during 2013 surveys, 

down from 389 individuals (2.2/hr.) and 

225 individuals (1.3/hr.) observed in the 

previous two survey years (2011 and 

2012, respectively) with similar 

sampling effort. In 2012, Long Lake Fen 

was thought to be the largest population 

of Poweshiek skipperling in the United 

States. However, it is subjected to 

intense development pressure, and 

results from 2013 surveys show low 

numbers. A fourth site, Grand River Fen 

(also known as Liberty Fen) in Jackson 

County, is approximately 100 km (62 

mi) from the other three sites, and was 

also considered to have good viability in 

2011, but the viability is questionable 

since 2013 surveys for the species were 

negative. In 2010, researchers counted 

54 (0.3/hr.) Poweshiek skipperling at 

Grand River Fen, and 114 (0.6/hr.) in 

2011 (Michigan Natural Features 

Inventory 2011, unpubl. data; Cuthrell 

2012a, pers. comm.). This number fell to 

14 (0.1/hr.) in 2012 and zero in 2013 

(Cuthrell, 2012a, pers. comm.; 2012b, 

pers. comm.; 2013, pers. comm.). 

Small populations, immediate threats 

that have significant impacts on the 

species, or both limit the viability of the 

remaining five sites where we consider 

Poweshiek skipperling to still be present 

in Michigan. In 2010, eight (0.1/hr.) 

Poweshiek skipperlings were recorded 

at Park Lydon in Washtenaw County; 12 

individuals were counted in 2011 (0.1/ 

hr.), 22 were counted in 2012 (0.2/hr.), 

and 1 individual was counted in 2013 

(Cuthrell 2012a, pers. comm.; 2013, 

pers. comm.). Two individuals (0.02/hr.) 

were recorded at Goose Creek 

Grasslands (also known as Little Goose 

Lake Fen) in Lenawee County in 2010, 

and nine (0.07/hr.) were seen in 2011 

(Cuthrell 2012a, pers. comm.; 2012b, 

pers. comm.). Only one Poweshiek 

skipperling was seen during a 15- 

minute 3-person survey in 2007 at the 

Snyder Lake site. Fourteen individuals 

were observed during 2008 surveys at 

Halstead Lake Fen (Michigan Natural 

Features Inventory 2011, unpubl. data), 

and 18 were observed in 2012 (Cuthrell 

2012a, pers. comm.); neither survey year 

had units of effort associated with the 

counts at this site. One individual was 

counted at Bullard Lake fen in 2007, but 

the species was not observed in the two 

most recent survey years (2008 and 

2009); therefore, the status is unknown 

at that site. We have only one year of 

data from Liberty Bowl Fen, where the 

species was recorded in 1996. The Eaton 

Road Fen is thought to be fairly viable, 

where 15–20 individuals were observed 

on multiple occasions in 2005, and a 

high of 68 individuals were observed in 

2011 (Cuthrell 2012b, pers. comm.). The 

Eaton Road site is approximately 0.6 km 

(1 mi) from the Long Lake Fen site and 

is considered a sub-site within Long 

Lake Fen (Cuthrell 2012b, pers. comm.), 

but we consider it to be a separate site 

for the purposes of this rule. 

To summarize, Poweshiek skipperling 

was historically documented in 17 sites 

in Michigan (Table 2). The species is 

considered to be present at 9 of the sites, 

although the numbers observed in 2013 

were substantially less than in previous 

years with similar survey effort. The 

occupancy is unknown at 2 sites, and 

the species is considered to be 

extirpated at 6 sites. 

Minnesota 

Minnesota historically contained 

approximately 48 percent (N=144) of all 

known records of Poweshiek 

skipperlings rangewide (Table 2). There 

are approximately 189 historical 

Poweshiek skipperling occurrence 

records in 32 counties in Minnesota 

[Minnesota Natural Heritage Inventory 

(MN NHI) database accessed June 19, 

2013, plus additional surveys]. Clusters 

of records occur within five general 

areas from the State’s southwest corner 

to near the Canadian border in the 

north. Based on the proximity of some 

occurrences to one another (e.g., 

overlapping or occurrences in close 

proximity to one another in one general 

location), there appear to be 

approximately 144 distinct historical 

site records in the State (Dana 2012d, 

pers. comm; Service 2014, unpubl. 

geodatabase). Poweshiek skipperling are 

presumed extirpated or possibly 

extirpated from at least 85 of these 

known sites. The status of the species is 

unknown at 58 sites, although 27 of 

those locations have not been surveyed 

since 2003, and the species has 

undergone a sharp decline in the State 

since then. 

An extensive survey effort was 

completed in 1993 and 1994 (Schlicht 

and Saunders 1994, entire; Schlicht and 

Saunders 1995, entire). During those 

surveys, Poweshiek skipperlings were 

found in 11 of 19 sites on which the 

species had been previously recorded 

and in 13 new sites, for a total of 25 of 

63 surveyed prairie sites; the species 

was present at 30 and 39 percent of the 

sites in 1993 and 1994, respectively 

(Schlicht and Saunders 1995, pp. 5–7). 

These results contrast sharply with 

those from the surveys conducted in 

2007 and 2008, when the species was 

found at four and zero percent of sites, 

respectively. Although the species was 

apparently more common in 1993 and 

1994, numbers of Poweshiek skipperling 

found during surveys were typically 

low. Large numbers were observed at 

only three sites (Schlicht and Saunders 

1995, p. 4). At one of these sites, Glynn 

Prairie, 25 Poweshiek skipperling were 

recorded during a 50-minute survey in 

July 1993 (Schlicht and Saunders 1995, 

data sheet); no Poweshiek skipperling 

were observed at this site during the 


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2007 survey despite good survey 

conditions (Selby 2009a, p. xxxv). 

Until about 2003, the Poweshiek 

skipperling was regarded as ‘‘the most 

frequently and reliably encountered 

prairie-obligate skipper in Minnesota’’ 

(Dana 2008, p. 1). Signs of the species’ 

decline in Minnesota were noted in 

2003 when Selby (2005, p. 20) found 

sharply lower numbers in and near 

Glacial Lakes State Park (Selby 2005, p. 

20) compared to those observed in 2001 

(Skadsen 2001, pp. 22–24). For example, 

numbers recorded along four transects 

that were surveyed in both years 

decreased from 104 to 2 individuals 

(Selby 2006b, Appendix 2, p. ii). In 2004 

and 2005, Selby (2006b, Appendix 2, 

p. 2) did not record a single Poweshiek 

skipperling on any of these transects in 

and around the park during 11 separate 

surveys. 

An extensive survey effort was 

conducted in 2007 and 2008 throughout 

most of the species’ known range in the 

State (Selby 2009a, entire). Sites with 

previous Poweshiek skipperling records 

that were considered to have the 

greatest conservation importance to the 

species (large, high-quality prairie 

remnants) were surveyed, as well as 

sites with no previous records that 

appeared likely to support the species 

(Selby 2009a, p. 2). In 2007, 70 sites in 

15 counties were surveyed, including 26 

sites with previous Poweshiek 

skipperling records (Selby 2009a, pp. 1, 

6). In 2008, 58 sites were surveyed in 13 

counties, including 22 sites with prior 

records (Selby 2009a, pp. 1, 6). A total 

of 34 sites with previous Poweshiek 

skipperling records were surveyed in 

both years combined. Poweshiek 

skipperling presence was recorded on 

only three of the 70 surveyed sites in 

2007; each of these three sites had just 

one confirmed individual (Selby 2009a, 

p. 1). No Poweshiek skipperlings were 

observed on any of the 58 sites surveyed 

during the 2008 flight period (Selby 

2009a, p. 1). 

In 2007, multiple transect surveys 

were conducted in four sites with 

previously well-documented Poweshiek 

skipperling populations—transects 

totaling 52,985 m (33 mi) were surveyed 

without observing a single Poweshiek 

skipperling (Dana 2008, p. 5). About 

half of these transects (totaling 20,959 m 

(13 mi)) were in the Prairie Coteau 

Scientific and Natural Area (SNA), 

where in 1990 Selby recorded 116 

Poweshiek skipperlings during the flight 

peak (Selby and Glenn-Lewin 1990, pp. 

19–20) along a total of about 6,250 m (4 

mi) of transects (Dana 2008, p. 16). No 

Poweshiek skipperling were observed 

during surveys of the Prairie Coteau 

SNA in 2012 (Runquist 2012, pp. 9–10). 

Additional surveys were conducted in 

2012; however, Poweshiek skipperling 

were not observed at any of the 18 sites 

with relatively recent records (Runquist 

2012, pp. 4–25; Selby 2012, p. 2; Selby 

2013, p. 2; Dana 2012c, pers. comm.; 

Runquist 2012a, pers. comm.; Olsen 

2012a, pers. comm.). Fifteen additional 

prairie sites with potential habitat or 

records of other skippers were surveyed 

in 2012, but no Poweshiek skipperling 

were observed (Runquist 2012, pp. 4– 

25; Selby 2012, p. 2; Selby 2013, p. 2; 

Dana 2012c, pers. comm.; Runquist 

2012a, pers. comm.; Olsen 2012a, pers. 

comm.). Twenty-one sites with previous 

records of the species were resurveyed 

in 2013 and 7 additional sites, with no 

previous records, were also surveyed for 

the species (Runquist 2014, pp. 3–6; 

Selby 2014, pp. 2–5; Rigney 2013b, p. 

Appendix B). Three individual 

Poweshiek skipperlings were observed 

at one site in Polk County—this is the 

first credible sighting of the species in 

the State since 2007 (Webster 2013, 

pers. comm.; Dana 2014, pers. comm.; 

Service 2014, unpub. database). 

Nearly half (approximately 48 

percent) of all documented Poweshiek 

skipperling sites rangewide are in 

Minnesota, thus the apparent collapse of 

large numbers of Poweshiek skipperling 

populations across the State may pose a 

significant challenge for the long-term 

existence of this species. Although the 

possibility remains that the species is 

extant at some sites where recent (2007, 

2008, 2012, or 2013) surveys were 

negative, it seems unlikely that it is 

present at those sites in any significant 

numbers. Extensive surveys in 1993 and 

1994 documented the species at about 

35 percent of all surveyed sites, whereas 

the 2007 effort found them at only about 

2 percent of all sites surveyed; no 

Poweshiek skipperling were detected 

despite widespread and robust survey 

efforts involving multiple observers in 

2008 or 2012 (Dana 2008, p. 8; Selby 

2009a, p. 1; Dana 2012c, pers. comm.; 

Runquist 2012a, pers. comm.; Olsen 

2012, pers. comm.; Runquist 2012, pp. 

4–25; Selby 2012, p. 2, 2013, p. 2). 

Three individuals were sighted at one 

location in 2013 (Webster 2013, pers. 

comm.; Dana 2014, pers. comm.). 

To summarize, Poweshiek skipperling 

was historically documented in 

approximately 144 sites in Minnesota 

(Table 2). The species is not considered 

to be present at any of these sites, except 

at one location (Table 2). The occupancy 

is unknown at 58 sites, and the species 

is considered to be extirpated or 

possibly extirpated at 21 and 64 sites, 

respectively (Table 2). 

North Dakota 

North Dakota historically contained 

approximately 6 percent (N=17) of all 

known records of Poweshiek 

skipperlings rangewide (Table 2). 

Poweshiek skipperlings have been 

historically documented at 17 sites 

(Table 2) in 7 North Dakota counties 

(Selby 2010, p. 18; Service 2014, 

unpubl. geodatabase): Cass, Dickey, 

LaMoure, Ransom, Richland, and 

Sargent in the southeastern corner of the 

State and Grand Forks County in the 

Northeast. Poweshiek skipperling are 

now considered extirpated or possibly 

extirpated from nine sites and four 

counties (Cass, Dickey, LaMoure, and 

Grand Forks) in North Dakota. The 

status of the species is unknown at 8 

sites, where the species was last 

observed between 1996 and 2001, but 

not during the most recent 1–2 year(s) 

surveyed. Four sites with fairly recent 

Poweshiek skipperling records were 

surveyed in 2012; Poweshiek 

skipperling were not found at any of 

those sites (Royer and Royer 2012b, pp. 

21–24; Royer and Royer 2012a, p. 6). 

One additional site was surveyed, 

which had the potential for Poweshiek 

skipperling presence because of its 

proximity to a known site for the 

species; however, no Poweshiek 

skipperling were found (Royer and 

Royer 2012b, pp. 18–19; Royer and 

Royer 2012a, p. 6; Royer 2012b, pers. 

comm.). The species was not observed 

at six sites with previous records of 

Poweshiek skipperlings that were 

surveyed in 2013. The species 

occupancy at two of these sites with 

2013 surveys was updated from 

unknown to extirpated based on three 

consecutive years of negative surveys 

(Service 2014, unpubl. geodatabase). 

The Poweshiek skipperling was 

known from seven North Dakota sites 

across six counties in the 1990s; 

however, only two of those sites were 

considered to have extant populations at 

that time; three records were 

represented by incomplete or 

ambiguous locality data, and the species 

was assumed to be extirpated at one site 

(Royer and Marrone 1992b, pp. 8–11). 

Surveys conducted in the State after 

1992 documented additional 

populations, but the most recent surveys 

at these sites were mostly negative. 

Orwig discovered eight new populations 

of Poweshiek skipperling (six in 

Richland County and two in Sargent 

County) during 3 years of survey work 

(1995–1997) in southeastern North 

Dakota (Orwig 1995, pp. 3–4; Orwig 

1996, pp. 4–6, 9–12; Orwig 1997, p. 2). 

The species was found at two of the 

eight sites surveyed in 1997 (Orwig 


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1997, p. 2) and at two additional sites 

in 1996 (Spomer 2004, p. 11). 

Once abundant at several known sites 

in North Dakota, Poweshiek 

skipperlings have experienced a 

dramatic decline over the last few 

decades. In 1977, McCabe and Post 

(1977a, p. 38), for example, found 

Poweshiek skipperling to be abundant at 

McLeod Prairie in Ransom County, 

stating that they could ‘‘be collected two 

at a time on the blossoms of Longheaded coneflower . . .’’ In 6 years of 

subsequent monitoring (1986–1991), 

however, Royer failed to find a single 

Poweshiek skipperling at the site after it 

was converted to a cattle-loading area 

(Royer and Marrone 1992b, p. 10). Royer 

and Marrone (1992b, pp. 10–11) 

assumed the species had been 

extirpated at this site. Similarly, the 

number of Poweshiek skipperlings 

recorded during surveys at the West 

Prairie Church site along the boundary 

of Cass and Richland counties, fell from 

hundreds in 1986, to four in 1990, and 

zero in 1991 and 2012 (Royer and 

Marrone 1992b, p. 8; Royer and Royer 

2012b, p. 21). Poweshiek skipperlings 

are unlikely to persist at this small and 

isolated site (Royer and Royer 2012b, p. 

21; Royer 2012c, pers. comm.). 

The last observation of a live 

Poweshiek skipperling in North Dakota 

was in 2001, at a new site discovered by 

Spomer (2001, p. 9) in Ransom County. 

Poweshiek skipperlings were not found 

in subsequent surveys at this site in 

2002, 2003, and 2012 (Spomer 2001, p. 

2; Spomer 2002, p. 3; Spomer 2004 p. 

36; Selby 2010, p. 18; Royer and Royer 

2012b, p. 22), although the 2012 survey 

may have been conducted too late in the 

year to detect the species at that site 

(Royer 2012b, pers. comm; Royer 2012d, 

pers. comm.). Therefore, the status of 

the species at this site is unknown. 

To summarize, Poweshiek skipperling 

was historically documented in 17 sites 

in North Dakota (Table 2). The species 

is not considered to be present at any of 

these sites (Table 2). The occupancy is 

unknown at eight sites, and the species 

is considered to be extirpated or 

possibly extirpated at three and six 

sites, respectively (Table 2). 

South Dakota 

South Dakota historically contained 

approximately 24 percent (N=69) of all 

known records of Poweshiek 

skipperlings rangewide (Table 2). The 

Poweshiek skipperling has been 

historically documented at 

approximately 69 sites (Table 2) across 

10 counties in South Dakota (Selby 

2010, p. 19). Based on expert review and 

additional survey and habitat 

information, the status of the species 

was determined to be unknown at 36 

sites, possibly extirpated at 2 sites, and 

presumed extirpated at the remaining 31 

sites (Table 2); at least 8 of the 

extirpated sites have been destroyed by 

conversion, gravel mining, loss of native 

vegetation, flooding, or heavy grazing 

(Skadsen 2012c, pers. comm.). 

The Poweshiek skipperling was not 

detected at any site that was surveyed 

between 2009 and 2013: 6 sites in 2009, 

10 sites in 2010, 1 site in 2011, 10 sites 

in 2012, and 25 sites in 2013 (Skadsen 

2009, p. 12; Skadsen 2011, p. 5; Skadsen 

2010, pers. comm.; Skadsen 2012a, pers. 

comm.; Skadsen 2012b, p. 3; Skadsen 

2013, pp. 3–4). The 2009 to 2013 results 

are in marked contrast to surveys 

conducted in 2002 when the species 

was recorded at 23 of 24 sites surveyed 

(Skadsen 2003, pp. 11–45). Cool and 

wet weather may have depressed 

butterfly populations, in general, in 

eastern South Dakota and west-central 

Minnesota in 2009 as it apparently did 

in 2004 (Skadsen 2004, p. 2; Skadsen 

2009, p. 2). In 2012 and 2013, five and 

nine additional sites, respectively, with 

potentially suitable native-prairie 

habitat but with no previous records of 

the species were surveyed, but no 

Poweshiek skipperling were observed 

(Service 2014, unpubl. geodatabase). 

Wisconsin 

Wisconsin historically contained 

approximately 1 percent (N=4) of all 

known records of Poweshiek 

skipperlings rangewide (Table 2). 

Naturalists reported Poweshiek 

skipperling to be common to abundant 

on prairies in southeastern Wisconsin in 

the late 1800s (e.g., in Milwaukee and 

Racine Counties), although exact 

localities are unknown (Borkin 2011, in 

litt.; Selby 2010, p. 22). By 1989, 

however, the species was listed as State 

endangered (Borkin 2011, in litt.). The 

Poweshiek skipperling is considered to 

be present at one site in Wisconsin 

(Table 2); Puchyan Prairie State Natural 

Area (SNA) is approximately 100 km (62 

mi) to the northwest of the Kettle 

Moraine State Forest in Green Lake 

County. The status of the species is 

unknown at three sites within the 

Southern Unit of the Kettle Moraine 

State Forest in Waukesha County. An 

additional 2010 record of a butterfly was 

incorrectly identified as a Poweshiek 

skipperling at Melendy’s Prairie Unit of 

the Scuppernong Prairie SNA (Borkin 

2012b, pers. comm.). 

The two occurrences of Poweshiek 

skipperling in the Kettle Moraine State 

Forest inhabit small areas that were 

once part of a larger prairie complex, 

which was fragmented by conversion to 

agriculture, other human development, 

and encroachment of woody vegetation 

(Borkin 2011, in litt.). Up until 2013, the 

largest population in Wisconsin was 

within a 6-ha (15-ac) prairie remnant on 

Scuppernong Prairie SNA at Kettle 

Moraine State Forest, which had record 

counts exceeding 100 individuals in 

1994, 1995, 1998, and 1999 (Borkin 

1995, p. 10; Borkin 1996, p. 7; Borkin 

2000, p. 4; Borkin 2011, in litt.). Four 

were found in 2007 (Borkin 2008, in 

litt., p. 1), although these data were 

collected during a single transect survey 

that may have been early in the flight 

season and are, therefore, not 

comparable to other survey years 

(Borkin 2012a, pers. comm.). A 

maximum count of 42, 17, 63, and 45 

were counted in 2009, 2010, 2011, and 

2012, respectively (Borkin 2011a, pers. 

comm.; Borkin 2012c, pers. comm.). The 

relatively low maximum count in 2010 

may be due to the timing of the flight 

(early) and the timing of the survey 

effort (late); therefore, the peak flight 

may have been missed (Borkin 2013, 

pers. comm.). A controlled burn in late 

March of 2012 may correlate with lower 

numbers observed during the 2012 flight 

(Borkin 2012a, pers. comm.). While this 

difference may be within the range of 

variation observed over the previous 4 

years (Wisconsin DNR 2012, in litt.), the 

range in variation may be skewed due 

to the low numbers observed in 2010 

due to the timing of the flight and the 

survey effort (Borkin 2013, pers. 

comm.). No Poweshiek skipperlings 

were observed at Scuppernong during 

repeated surveys in 2013 (Borkin 2013, 

pers. comm.)—this is the first time no 

individuals have been observed there 

since regular surveys began in the 1990s 

(Borkin 2014 pers. comm.). Each year, 

surveys were conducted with similar 

effort—modified Pollard transect 

covering 15 ac (6 ha) in approximately 

40 minutes (Borkin 2014, pers. comm.). 

After brush was cleared from the area 

in 2002, a small number of Poweshiek 

skipperlings were discovered the 

following year in a small isolated prairie 

remnant patch at a second site in the 

Kettle Moraine State Forest, (Borkin in 

litt 2008). Once the intervening woody 

growth was removed, individuals 

presumably dispersed from the 

Scuppernong SNA remnant prairie to a 

small habitat patch about 200 ft (61 m) 

away (Borkin 2012a, pers. comm.). 

Surveys at each habitat patch have 

consistently yielded counts of less than 

10 (Borkin 2008, in litt.), with a 

combined high count of 11 to 15 

individuals in 2011. A total of six 

individuals, with a high single day 

count of three, were observed in eight 

surveys during 2012 (Borkin 2012c, 


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pers. comm.; Borkin 2012a, pers. 

comm.). No Poweshiek skipperlings 

were observed in 2013 (Borkin 2013, 

pers. comm). 

The status of the Poweshiek 

skipperling is unknown at a third and 

much larger fragment of Kettle Moraine 

State Forest, the Kettle Moraine Low 

Prairie SNA, which is adjacent to the 

Wilton Road site. The Kettle Moraine 

Low Prairie SNA was overgrown by 

shrubs including willows (Salix spp.), 

quaking aspen (Populus tremuloides), 

and glossy buckthorn (Frangula alnus) 

and has been managed with a series of 

controlled burns, in addition to a 1975 

wildfire (Borkin 2011, in litt; Borkin 

2012a, pers. comm.; Wisconsin DNR 

2012, in litt). The highest number 

recorded at the Kettle Moraine Low 

Prairie SNA was 28 on July 8, 1995 

(Borkin 2012a, pers. comm.). 

Preliminary attempts in 2000 to 2003 to 

augment the population with adults 

from Scuppernong SNA and captivereared larvae were not successful 

(Borkin 2012a, pers. comm.). A single 

Poweshiek skipperling was sighted 

there on July 2, 2004, but none were 

found in surveys conducted in 2007– 

2009 and 2011–2012 (Borkin 2011b, 

pers. comm.; Borkin 2012a and 2012c, 

pers. comm.). Two Poweshiek 

skipperlings were recorded in 2010 at 

this site (Wisconsin DNR2012, in litt.); 

however, no photographs or voucher 

specimens confirm the sighting. This 

site was surveyed less intensively than 

Scuppernong Prairie, because of the 

species’ relatively low density and 

abundance at Kettle Moraine Low 

Prairie SNA (Borkin 2012a, pers. 

comm.). Extensive brush cutting, 

additional burns, and restoration of the 

hydrology have been undertaken in 

recent years (Borkin 2012a, pers. 

comm.). 

Poweshiek skipperlings are present at 

a third site in Wisconsin, Puchyan 

Prairie SNA, in Green Lake County, 

although this population is small and 

declining (Borkin 2009, pers. comm.). 

The Poweshiek skipperling was first 

discovered at Puchyan Prairie in 1995, 

and 6 to 30 individuals have been 

recorded in subsequent surveys (Borkin 

2008, in litt.; Swengel 2012, pers. 

comm). In 2012, Swengel (2012, pers. 

comm.) found a maximum of three 

individuals, despite several hours of 

searching over 3 days. In 2013, Swengel 

(2013, pers. comm.) found a total of 

three individuals during 2 days of 

searching. 

Additional sites in eight counties 

(Crawford, Grant, Iowa, Jefferson, 

Monroe, Rock, Sauk, and Walworth) 

have been surveyed in an attempt to 

find undiscovered Poweshiek 

skipperling populations. Four of the 

eight sites surveyed in 1998 and 1999 

seemed to have adequate host plants, 

nectar resources, and size typical of 

Poweshiek skipperling habitat, but 

Poweshiek skipperling were not present 

at any of the sites (Borkin 2000, pp. 5– 

7). 

To summarize, Poweshiek skipperling 

was historically documented in 4 sites 

in Wisconsin (Table 2). The species is 

considered to be present at one site and 

the occupancy is unknown at three sites 

(Table 2). 

Manitoba 

Manitoba historically contained less 

than 1 percent (N=1) of all known 

records of Poweshiek skipperlings 

rangewide (Table 2); however, multiple 

Poweshiek skipperling historical 

records occur in one general location— 

a complex of several nearby small sites 

within the Tallgrass Prairie Preserve—in 

far southern Manitoba, near the United 

States border. Poweshiek skipperlings 

were first recorded in Canada near Vita, 

Manitoba, in 1985 at each of seven 

prairies surveyed, and populations were 

described as abundant but localized 

(Catling and Lafontaine 1986, p. 63). 

Poweshiek skipperlings were found at 

15 of 18 locations surveyed within the 

same area in 2002 (COSEWIC 2003, p. 

5). 

The Poweshiek skipperling is 

currently present at one location in 

Canada, The Nature Conservancy of 

Canada Tall Grass Prairie Preserve near 

Vita, Manitoba (Westwood 2010, p. 2; 

Westwood et al. 2012, p. 1; Hamel et al. 

2013, p. 1). Poweshiek skipperlings 

were historically moderately common in 

areas of the preserve (Klassen et al. 

1989, p. 27). In 2002, Webster (2003, p. 

5) counted approximately 150 

individuals, and in 2006, approximately 

126 individuals were sighted across 10 

sites (Westwood 2010, p. 3). Surveys of 

10 sites in 2008 and 2009 yielded 281 

and 79 Poweshiek skipperlings, 

respectively (Dupont 2010, pers. 

comm.). Poweshiek skipperling 

numbers in the preserve declined 

sharply after a 647-ha (1,600-ac) wildfire 

in fall 2009 burned much of the species’ 

habitat, including areas that likely 

contained the largest and highest 

density populations (Westwood 2010, p. 

2); surveys of comparable effort to the 

2008 and 2009 surveys yielded only 13 

Poweshiek skipperlings on the preserve 

in 2010 (Westwood 2010, pp. 7–22). 

Surveys of 45 sites within the Tall Grass 

Prairie Reserve during 2011 resulted in 

13 sites with positive sightings, 9 of 

which were new sites (Westwood et al. 

2012, p. 11; Dupont 2011, pers. comm.). 

The average number of Poweshiek 

skipperlings found at each site ranged 

from 10 to 15 per hour. These numbers 

are up considerably from 2010, but not 

as high as observed in 2008 (Dupont 

2011, pers. comm.). In 2012, a total of 

50 individuals were observed, which 

was ‘‘low when compared to historic 

densities’’ (Hamel et al. 2013, p. 17). 

Poweshiek skipperling sites in Manitoba 

are often surveyed up to 7 times during 

the flight period each year (Westwood 

2013, pers. comm.). The preserve has 

detailed management recommendations 

to facilitate recovery of the Poweshiek 

skipperling (Westwood 2010, p. 5). 

Following an assessment and status 

report completed in 2003 under the 

Committee on the Status of Endangered 

Wildlife in Canada (COSEWIC), the 

Poweshiek skipperling was listed under 

the Species at Risk Act as Threatened in 

Canada in July 2005 (COSEWIC 2003). 

A recovery strategy is now in place for 

the species in Canada (Environment 

Canada 2012), which includes critical 

habitat designations within and adjacent 

to The Nature Conservancy of Canada 

Tall Grass Prairie Preserve 

(Environment Canada 2012, p. ii). 

Summary of Comments and 

Recommendations 

In the proposed rule published on 

October 24, 2013 (78 FR 63574), we 

requested that all interested parties 

submit written comments on the 

proposal by December 23, 2013, during 

which we held public meetings on 

November 5, 2013, in Minot, North 

Dakota; November 6, 2013, in Milbank, 

South Dakota; November 7, 2013, in 

Milford, Iowa; November 13, 2013, in 

Holly, Michigan; and November 14, 

2013, in Berlin, Wisconsin. We also 

contacted appropriate Federal and State 

agencies, scientific experts and 

organizations, and other interested 

parties and invited them to comment on 

the proposal. Newspaper notices 

inviting general public comment were 

published in the following papers: 

Detroit Free Press, Detroit, MI; The 

Detroit News, Detroit, MI; Berlin 

Journal, Berlin, WI; The Forum of FargoMoorhead, Fargo, ND; Minneapolis StarTribune, Minneapolis, MN; Mukwonago 

Chief, Mukwonago, WI; The Des Moines 

Register, Des Moines, IA; Bismark 

Tribune, Bismark, ND; The Argus 

Leader, Sioux Falls, SD. We did not 

receive any requests for a public 

hearing. All substantive information 

provided during comment periods has 

either been incorporated directly into 

this final determination or addressed 

below. Comments specific to the 

proposed designation of critical habitat 

for the two species (78 FR 63625) will 


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be addressed in the final critical habitat 

determination. 

Peer Reviewer Comments 

In accordance with our peer review 

policy published on July 1, 1994 (59 FR 

34270), we solicited expert opinion 

from ten knowledgeable individuals 

with scientific expertise that included 

familiarity with the Dakota skipper or 

the Poweshiek skipperling and its 

habitat, biological needs, and threats. 

We received responses from seven of the 

peer reviewers. 

We reviewed all comments received 

from the peer reviewers for substantive 

issues and new information regarding 

the listing of the Dakota skipper or the 

Poweshiek skipperling. The peer 

reviewers generally concurred with our 

methods and conclusions and provided 

additional information, clarifications, 

and suggestions to improve the final 

rule. Peer reviewer comments are 

addressed in the following summary 

and incorporated into the final rule as 

appropriate. 

General 

(1) Comment: Peer reviewers thought 

that the Service’s interpretation of 

literature addressing threats to these 

species was well researched. However, 

some peer reviewers suggested that 

further research would strengthen or 

refine our understanding of these 

butterflies. 

Our Response: The Act requires us to 

make a determination on the status of 

species based on the best available 

information. However, we agree that 

that further studies of these species 

would further our understanding and 

help us with the recovery planning and 

implementation. We will consider 

further research needs in our recovery 

planning efforts. 

(2) Comment: One peer reviewer 

stated that, in the Executive Summary, 

the Service did not describe the effects 

of habitat management on butterflies, 

but rather focused on the impacts to 

native vegetation. 

Our Response: We have updated the 

executive summary to include the direct 

mortality that may occur due to 

management activities or natural 

occurrences. This subject is discussed in 

further detail in the Background section 

of this final listing rule. 

Taxonomy 

(3) Comment: One peer reviewer 

provided a correction to the number of 

subfamilies in the family Hesperiidae 

and the number of species in the genus 

Hesperia. Specifically, the family 

comprises 7 subfamilies world-wide, 4 

of which occur in North America, north 

of Mexico. There are 21 recognized 

species in the genus Hesperia (ibid), not 

18 as cited in the proposal. 

Our Response: We corrected the 

statements in the Background section of 

this final listing rule. 

Species Biology 

(4) Comment: One peer reviewer 

provided details on Dakota skipper and 

Poweshiek skipperling biology, 

specifically, information pertaining to 

early life stages and larval food choices, 

which were learned from captiverearing trials at the Minnesota Zoo. 

Our Response: We have incorporated 

the updated information into the 

Background section of this final listing 

rule. 

(5) Comment: Two peer reviewers 

suggested that we incorporate the 

findings of two recently published 

Master’s theses (Dupont 2013, Rigney 

2013a) that have new information on the 

Dakota skipper and Poweshiek 

skipperling, including data from surveys 

at several locations for both species in 

Manitoba. These studies also show a 

greater decline in both species in 

Canada over the last 10 years than is 

indicated in the proposed listing rule. 

Our Response: We incorporated data 

from the referenced Master’s theses in 

the Dakota skipper Background section 

in this final listing rule. The new 

information, although important to our 

full understanding of the status of the 

species throughout their ranges, does 

not change our listing determinations 

for the two species. 

(6) Comment: A peer reviewer stated 

that based on personal observations and 

McAlpine’s 1972 report, upon hatching, 

Poweshiek skipperling larvae crawl out 

near the tip of grasses, and do not crawl 

to the base of grasses, as was stated in 

the proposal. 

Our Response: We corrected the 

statement regarding Poweshiek 

skipperling larval behavior in the 

Background section of this final listing 

rule. 

(7) Comment: A peer reviewer noted 

that a species’ nectar preference is 

usually indicated by selection in greater 

frequency rather than the proportion of 

the species among all available nectar 

sources (because random selection 

would be expected to result in selection 

frequency equal to the species’ 

proportion of the available choices). All 

of the references cited in the rule report 

nectar preferences as the relative 

proportion among observed choices. 

Our Response: We clarified this point 

in the Background section of this final 

listing rule. 

Food and Water 

(8) Comment: Peer reviewers provided 

corrections to the lists of flowers used 

as nectar sources and the importance of 

several plants as nectar sources for the 

butterflies. 

Our Response: We corrected the 

nectar flowers for Dakota skipper 

accordingly in the Background section 

of this final listing rule. Also, we 

removed upright prairie coneflower, 

fleabane, and white prairie clover from 

our list of important nectar species. We 

did not remove black-eyed Susan, 

because Rigney (2013a, p. 142) reported 

Dakota skippers were frequently 

observed nectaring on that species in 

Canada. 

(9) Comment: One peer reviewer 

stated that the assertion that Dakota 

skipper larvae feed only on native 

grasses has not been established, and 

further stated that when confined with 

no other choice, Dakota skipper larvae 

may feed on a variety of native and 

nonnative grasses. Exotic cool-season 

grasses, such as Kentucky bluegrass and 

smooth brome are available, and 

generally of good nutritional quality, 

when overwintering larvae emerge from 

hibernation and begin feeding. The tight 

empirical correlation between 

occurrence of this skipper and the 

dominance of native plants in the 

habitat, however, indicates that the 

species requires native grasses. 

Our Response: We have incorporated 

this information into the final listing 

rule, and recognize that Dakota skipper 

larvae can use both native and 

nonnative plants as food during certain 

stages of larval development. Some 

exotic cool-season grasses may be 

suitable larval food plants during 

limited times of larval development; 

however, the morphology and growth of 

these grasses may determine the 

suitability for the species, and if those 

grasses dominate a site, the chances for 

larvae finding suitable food sources is 

decreased. 

(10) Comment: One peer reviewer 

provided additional information on 

observations of Poweshiek skipperling 

oviposition and larval food use in 

Wisconsin. 

Our Response: We have incorporated 

the information into the Background 

section of this final listing rule. 

(11) Comment: One peer reviewer 

corrected our interpretation of his 

observations on Poweshiek skipperling 

oviposition (egg-laying) to state that 

larvae need to begin feeding on very 

fine, threadlike blade tips, and that 

females placed eggs on fine blade tips of 

grasses during some observed 

ovipositions. 


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Our Response: We have incorporated 

this information into the Background 

section of this final listing rule. 

(12) Comment: One peer reviewer 

stated that the summary of the best 

available information for Dakota skipper 

dispersal is adequate and incorporates 

all of the information of which the 

reviewer is aware. The reviewer did 

correct our interpretation of Dana’s 1997 

mark-and-recapture study. The reviewer 

stated that roads and crop-fields were 

suspected to be impediments to Dakota 

skipper movement; however, this was 

not explicitly tested during the study. 

Another reviewer wanted clarification 

on our basis for the estimated maximum 

dispersal distance of the Poweshiek 

skipperling. 

Our Response: We corrected the 

dispersal section of this final rule to 

accurately present Dana’s 1997 markand-recapture study findings, and added 

information from an additional study. In 

one mark-and-recapture study in 

Manitoba, the Poweshiek skipperling 

was found within 50 m (165 ft) of its 

original capture location (Dupont 2013, 

p. 69). Besides this study in Manitoba, 

which had too few recaptures to make 

any statistically significant conclusions, 

we are unaware of any other dispersal 

studies for the species. Therefore, we 

used Dakota skipper (and dispersal 

studies on this species) as a surrogate 

species to estimate the maximum 

dispersal distance of the Poweshiek 

skipperling (e.g., Dana 1991, Dana 1997, 

Skadsen 1999a), and verified our 

assumptions with expert opinion and 

Burke (2011). Experts generally agreed 

that 1.6 km (1.0 mi) was a reasonable 

estimate for Poweshiek skipperling 

dispersal distance (Westwood 2012b, 

pers. comm.; Dana 2012b, pers. comm.). 

However, according to Burke et al. 

(2011), the Poweshiek skipperling was 

less mobile than the Dakota skipper. 

Since experts generally assumed the 

maximum dispersal distance of the 

Dakota skipper was 1 km (0.6 mi), we 

used 1 km (0.6 mi) as a conservative 

maximum dispersal distance for the 

Poweshiek skipperling. 

(13) Comment: One peer reviewer 

questioned the accuracy of the mobility 

value assigned to the Dakota skipper 

from the Burke et al. (2011) publication. 

The reviewer suggested that the 

strongest evidence for limited dispersal 

capabilities is the absence of 

observations outside of native-prairie 

habitat. Butterflies that are highly 

mobile are occasionally observed in 

unsuitable habitat; however, factors 

such as the rarity of the species, its 

small size and inconspicuous 

appearance, and the rarity of observers 

that are both interested in skippers and 

capable of identifying them, makes the 

absence of observations in unsuitable 

habitats weak evidence for the absence 

of movement over long distances. The 

reviewer further stated that, since we 

have little basis for measuring dispersal 

in this species, but we have no evidence 

that it does much dispersing, we should 

assume that dispersal is very limited. 

Our Response: The Burke et al. (2011) 

paper was published in a peer-reviewed 

scientific journal (using expert 

interviews); however, we recognize the 

limitations of the data therein and, 

therefore, have arrived at our conclusion 

that the Dakota skipper has low 

dispersal capability based on this paper 

in conjunction with other reports and 

observations. 

Habitat 

(14) Comment: One peer reviewer 

corrected the statement that Type B 

habitat (as explained in the Background 

section above) was the only habitat type 

inhabited by the Dakota skipper in 

Minnesota, as the species has been 

documented in other habitat types, 

particularly in Type A habitat in Kittson 

and Stearns Counties. 

Our Response: We corrected the 

statement regarding Dakota skipper 

habitat types in Minnesota in this final 

listing rule. It should be noted, however, 

that there is only one recent (2009) 

record of a Dakota skipper in Kittison 

County, Minnesota, and two sites in 

Stearns County where the species is 

possibly extirpated. 

(15) Comment: One peer reviewer 

stated that the assertion in our proposed 

rule that Dakota skipper larvae are 

‘‘particularly vulnerable to desiccation 

during dry summer months’’ was a 

hypothesis, with no confirming 

evidence. The paper cited only surveyed 

occupied habitat and did not test 

unoccupied areas for the same 

parameters. 

Our Response: We realize the 

limitations of Royer’s 2008 study, and 

have corrected our interpretations 

accordingly in this final rule; 

specifically, the sampling design 

(edaphic parameters were measured 

only in occupied areas, and no 

unoccupied areas were examined to test 

the significance of the findings) does not 

allow for statistically significant 

conclusions. 

(16) Comment: One peer reviewer 

corrected the definition given for ‘‘larval 

nesting zones’’ measured for edaphic 

characteristics in Royer (2008). The 

‘‘primary larval nest zone’’ in which 

they measured temperature and 

humidity is described as 0–2 cm above 

the soil surface, not between the soil 

surface and 2 cm deep as stated in the 

proposed rule. 

Our Response: We have corrected the 

statement regarding larval nesting zones 

in the Background section of this final 

rule. 

Occupancy 

(17) Comment: Ane peer reviewer 

commented on the adequacy of the 

categorization of population status, and 

stated that it was done in an 

appropriately conservative way, but did 

not think this would affect the ultimate 

decision for either species 

Our Response: We developed the 

occupancy criteria to be as objective as 

possible in light of the information we 

had, which was complicated by the 

variability of the frequency and lack of 

error quantification of the survey data. 

We applied the occupancy rules 

consistently, in the same way 

throughout the range of each species, 

with discretion given to species experts 

who were familiar (e.g., who had 

conducted relatively recent site visits or 

butterfly surveys) with the sites within 

their State. Using the best information 

available, we attempted to balance our 

determination as to whether the species 

was likely present or not at a particular 

location. We determined that at sites 

where the species was detected during 

the most recent survey, if the survey 

was conducted in 2002 or more 

recently, this was a reasonable 

timeframe to assume its presence, if 

there was no evidence of habitat 

destruction or significant degradation of 

the habitat. Some other comments, 

however, indicated that the 10-year 

timeframe was too long to assume 

presence of an annual species, such as 

these butterflies, while others thought 

we should still be assuming presence at 

locations with detections much farther 

back (prior to 1993), if we had no 

evidence that the habitat hadn’t been 

destroyed there. However, we believe 

that we have taken the most reasonable 

approach to defining occupancy, used 

the best available scientific information 

appropriately, and have been consistent 

in making this determination. 

(18) Comment: One peer reviewer 

noted that it would be useful to clarify 

the importance of unknown sites and to 

determine if habitat in ‘‘unknown’’ sites, 

and sites where extirpation has 

presumed to have occurred, is actually 

in a condition to support future 

populations, particularly for future 

reintroductions. 

Our Response: It is important to 

distinguish among sites where the 

species is likely extirpated, where the 

species is still present, and where we 

are unsure of the species’ presence, in 


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order to determine the current status of 

these species. The habitat at individual 

sites varies, but where we had evidence 

that the habitat was destroyed, we 

considered those sites to be extirpated 

(and, thus, unsuitable for future 

reintroductions). The habitat at other 

sites may still be suitable for one or both 

species, and its role in future recovery 

efforts, such as reintroductions, will be 

considered during the recovery 

planning and implementation phase for 

these species. 

(19) Comment: One peer reviewer 

requested that we define some terms 

used in the proposed rule; in particular, 

the terms ‘‘positive detections,’’ 

‘‘detection rate,’’ and ‘‘liv’’. 

Our Response: Positive detections 

refers to the number of times the species 

was detected during a survey. Detection 

rate is calculated as the number of times 

the species was detected (at a singular 

site or groups of sites), divided by the 

number of surveys (at a singular site or 

groups of sites). Finally, ‘‘liv’’ refers to 

the page number in the preface of a 

cited publication (Roman numeral for 

page 54). 

(20) Comment: Does the definition of 

species extirpation from a site apply to 

surveys conducted in 1993, or to those 

done more recently? 

Our Response: We considered the 

species to be extirpated from a site if 

there were at least three sequential years 

of negative surveys, no matter the year 

those sites were surveyed, and the 

species has not subsequently been 

documented at the site. For example, if 

a site was only surveyed in 1991, 1995, 

and 1999, and there were no positive 

detections of the species during all 3 

years, we assumed that the species is 

extirpated from that site. The species 

occupancy at that site would not change 

unless the species is detected at that site 

in the future. We have clarified this 

definition in the Background section of 

this final listing rule. 

(21) Comment: One peer reviewer 

wanted further clarification on our 

justification for including four Dakota 

skipper sites with older records in the 

present occupancy category. The 

reviewer suggested we review the 

previous densities of the species at the 

four sites and the proximity of nearby 

sites from which individuals could 

recolonize the sites in question. 

Our Response: The species occupancy 

at one of four South Dakota sites has 

been updated to ‘‘unknown’’ after 

further review of the information 

available for the site, including 2013 

survey data that were not available to us 

at the time we drafted the proposed 

rule. However, there is no evidence to 

suggest that the species is not still 

present at the remaining three sites (all 

in Minnesota), because the best 

information indicates that the sites’ 

habitats are still suitable for the 

butterfly, and, therefore, despite the lack 

of recent surveys, the species may still 

be present there. 

(22) Comment: A peer reviewer noted 

that at several points the proposed rule 

indicates that survey efforts may vary in 

number of visits, but that certain survey 

results were not considered, because 

they were not conducted at the 

appropriate time. The peer reviewer 

questioned whether we can presume 

that the surveys that were considered 

are comparable, regardless of the 

number of visits visits, whether those 

surveys all meet some minimum 

criteria, and whether there was a 

standard survey effort measurement. 

Our Response: Since the purpose of 

site surveys differed by site, the amount 

of effort also varied. For example, if the 

goal of the survey was to verify if the 

species was present at a particular 

location, a surveyor may have stopped 

the survey effort as soon as the first 

individual was detected, which may 

have occurred after a short, one-time 

visit. On the other hand, if the survey 

purpose was to count individuals 

during the peak flight of a species, the 

site may have been visited every day 

throughout the adult flight period, and 

more quantitative measurements, such 

as number of individuals observed per 

hour, may have been recorded. We used 

all types of surveys, as long as they were 

conducted during the appropriate time 

of the year (mid-June through mid- to 

late July), and during appropriate 

conditions (e.g., generally wind speeds 

less than 16 mph, unless the species 

was detected at higher speeds). 

Furthermore, we only considered 

surveys from individual surveyors who 

are able to reliably identify the species 

in the field. 

(23) Comment: A peer reviewer noted 

that the proposed rule states that 

existing models are unable to identify 

specific plant species, invasive species, 

and floristic quality, and the Service 

concludes that unbroken grasslands 

‘‘may not contain the specific native 

prairie plants that the Dakota skipper 

requires. . . .’’ This statement appears 

to be contradicted later in the 

document. 

Our Response: We clarified the 

statements in this final listing rule. The 

intent of the first statement is to 

acknowledge that existing habitat 

models cannot identify specific species 

or determine floristic quality necessary 

to support Dakota skipper populations. 

The models may be useful in narrowing 

down areas that may contain the 

necessary nectar plants and larval food 

plants, but presence of specific plant 

species and suitability for the Dakota 

skipper must be verified by other means 

(e.g., on the ground plant surveys). The 

second statement refers to the 

possibility of yet undiscovered areas of 

suitable habitat where the Dakota 

skipper may exist, because not every 

area that is suitable has been surveyed 

for the species. 

(24) Comment: A peer reviewer noted 

that survey site selection may be 

influenced by the expert’s knowledge of 

potential habitats, land ownership, and 

the ability to gain landowner permission 

to access areas for surveys. 

Our Response: We acknowledge that 

survey sites may be selected for a 

variety of reasons. A site may be 

surveyed because there is known 

suitable prairie habitat in an area, but 

the exact survey location may depend 

on other variables, such as the ability to 

gain landowner permission to survey. 

Status and Trends 

(25) Comment: One peer reviewer 

provided additional 2009 data for the 

Felton Prairie site in Minnesota. 

Our Response: We incorporated this 

data into this final listing rule. 

(26) Comment: One peer reviewer 

requested clarification on the butterfly 

survey methodology and how floristic 

diversity was rated at some of the 

survey locations. 

Our Response: The survey 

methodology varied among locations, 

years, surveyors, and by other factors, 

and it is difficult to succinctly describe 

the methodology used for more than 20 

years of surveys for hundreds of survey 

sites. For that reason, we examined the 

data in terms of the rate of positive 

detections over the years at each survey 

location as a way to compare data across 

multiple survey methods and years. We 

applied certain standards that each 

survey must meet (see response to 

comment 22, above). In this final listing, 

we describe survey methods or floristic 

quality determination methods for 

specific locations when it is necessary 

to understand the results for a particular 

survey, and describe typical survey and 

floristic methodologies in the 

Background section of this final rule. 

(27) Comment: A peer reviewer 

commented that the number of 

historical populations of Dakota skipper 

that remain extant is probably 

overestimated, given the results of 

recent resurvey efforts. In particular, 

this peer reviewer questioned whether it 

was realistic to assume species presence 

at five Minnesota sites, given the 

dramatic declines and apparent 

extirpation of populations at some of the 


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best sites within recent years. The 

reviewer suggested assigning those sites 

as ‘‘possibly present’’ or ‘‘status 

unknown’’ category, and targeting these 

sites for future surveys to determine the 

species’ presence, particularly because 

recent declines do not appear to be due 

to habitat degradation or loss. 

Our Response: Based on 2013 survey 

data, we changed the occupancy for 

several sites. When determining species 

occupancy at a site, we balanced 

information on habitat succession with 

the available survey data to avoid falsely 

assuming the species is absent from 

less-surveyed sites that still have 

suitable habitat. 

(28) Comment: A peer reviewer 

commented that, based on surveys 

conducted in 2013, the status of both 

the Dakota skipper and the Poweshiek 

skipperling in Minnesota is likely more 

dire than suggested in the proposal. No 

Dakota skippers or Poweshiek 

skipperlings were observed during 

duplicate surveys conducted at 13 sites. 

During single surveys conducted later in 

the flight period (the time when adult 

butterflies are able to fly) at two 

additional sites in Clay County, MN, six 

Dakota skippers were seen at one of 

those sites and no Poweshiek 

skipperling were observed at either site. 

Both sites had fairly good numbers 

during 2008 surveys. Additionally, one 

peer reviewer suggested that we 

incorporate results from 2013 surveys of 

sites in Kittson County, Minnesota. No 

Dakota skippers were observed at Lake 

Bronson in 2013; however, there was 

one highly likely sighting, and the area 

contains moderate-quality habitat. The 

Frenchman’s Bluff sites in Minnesota 

were surveyed on July 11, 2013, which 

was during the period of peak 

abundance in the phenologically 

(relationship between a periodic 

biological phenomenon and climatic 

conditions) delayed year, but the Dakota 

skipper was not observed. The 

estimated probability of the species 

presence at the site is 90 percent, based 

on the abundance of habitat and purple 

coneflower in bloom. 

Our Response: We incorporated the 

2013 data into this final listing rule. Due 

to several negative results from 2013 

surveys, particularly in Minnesota, the 

occupancy status at several sites has 

been updated in this final listing rule. 

We still determine that the Dakota 

skipper should be listed as threatened, 

and provide justification for our 

determination in this final listing rule. 

(29) Comment: One peer reviewer 

suggested that we incorporate 

information from a 2013 report of 

butterfly surveys in South Dakota. 

Our Response: We incorporated 2013 

survey results in this final listing rule. 

(30) Comment: A peer reviewer 

suggested that the Dakota skipper 

population densities as described in 

2003 and 2007 status assessments may 

no longer accurately describe the 

populations and the threats causing 

population declines. For example, 

reported sightings of Dakota skippers 

within the Riding Mountain National 

Park in Manitoba (Walleyn 2002) are 

likely not valid; there are no voucher 

specimens to confirm the report. There 

are no known sites that are owned by 

the Government in Canada. 

Our Response: We incorporated 

updated information regarding several 

sites in Manitoba and Saskatchewan. 

We have no records of any confirmed 

Dakota skipper sites within the Riding 

Mountain National Park in Manitoba. 

(31) Comment: One peer reviewer 

noted that there has been a decline in 

the number of individual Dakota 

skippers observed during the flight 

period compared to the populations 

observed in 2002 and 2007. The current 

population estimates are much lower 

than those described in Webster’s 2002 

and 2007 reports. Furthermore, the 

methods for estimating densities have 

changed; survey methodology has 

become more rigorous, with 2 to 5 visits 

per site per year from 2009–2013 

compared to single visits prior to 2008. 

Our Response: We incorporated 2013 

data into this final listing rule. Due to 

largely negative results from 2013 

surveys, the occupancy status of the 

species at several sites has been updated 

in this final listing rule. 

(32) Comment: One peer reviewer 

stated that there is a DuPage County, 

Illinois, record of a Poweshiek 

skipperling—the specimen was 

collected in 1968 near the DuPage River, 

and was only recently identified as a 

Poweshiek skipperling. 

Our Response: We have added the 

DuPage County record to the Illinois 

status and distribution section of this 

final listing rule. 

(33) Comment: One peer reviewer 

stated that, because no Poweshiek 

skipperlings were observed in 2013 at 

Scuppernong Scientific and Natural 

Area (SNA) in Wisconsin, nor at the 

nearby Wilton Road site, those 

populations may be extirpated. The peer 

reviewer also stated that the apparent 

decline in numbers was also observed in 

Michigan. 

Our Response: We have updated the 

Background section of this final listing 

rule to include the 2013 data for those 

two locations. Because there are just one 

or two years of negative data at the 

Scuppernong SNA and Wilton Road 

sites, the occupancy status at both sites 

is unknown. 

(34) Comment: A peer reviewer 

commented that the low numbers of 

Poweshiek skipperling observed in 2012 

at Scuppernong SNA were at least 

partially due to the spring burns of 25– 

30 percent of their prime breeding 

habitat at that location. The range of 

variation of the maximum numbers 

observed in 2009–2012 may be skewed 

due to the low numbers observed in 

2010, when the peak flight may have 

been missed due to an early flight and 

late survey effort. The anticipated 

increase in the population in 2012 due 

to a mild winter and early spring 

phenology was not observed, which 

may indicate that the burn killed a high 

number of larvae. 

Our Response: We clarified the 

statements regarding the uncertainty of 

the effect that the 2012 spring burn had 

on the Poweshiek skipperling 

population at that location. It is difficult 

to make cause-and-effect statements 

without direct measures of larvae 

mortality following a burn. 

(35) Comment: A peer reviewer stated 

that the same protocol has been used for 

Poweshiek skipperling surveys in 

Wisconsin since the early 1990s—a 

modified Pollard transect count with a 

set transect pattern covering 6 ha (15 ac) 

of area and 40 minutes to complete. 

Our Response: We clarified the 

methodology used at the Scuppernong 

SNA sites in the Background section of 

this final listing rule. 

Factors Affecting the Species 

(36) Comment: A peer reviewer 

suggested that it would be useful to rank 

or evaluate risks to the butterfly 

populations as they relate to 

management recommendations. For 

example, would haying carry a lower 

risk of causing extirpations? The level of 

risk, however, would depend on the 

type, duration, and timing of haying 

activities versus the type of fire 

management applied to sites. 

Our Response: Ranking management 

methods goes beyond the scope of this 

final listing document and is more 

appropriate for recovery planning. 

Furthermore, management 

recommendations may vary for each 

location, based on the habitat type and 

condition; therefore, it may not be 

possible to generalize the level of risk 

associated with various management 

types. 

(37) Comment: One peer reviewer 

commented on the level of private 

landowner awareness of the species and 

its status on their lands. Specifically, in 

Canada, most private landowners are 

unaware of the presence of the Dakota 


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skipper, and this may also be true for 

private landowners in the United States. 

Even where current management on 

lands may be conducive to the species, 

it is not typically due to a conscious 

effort to conserve the species. 

Landowner apathy should be 

considered a threat of considerable 

concern. 

Our Response: We agree that some 

landowners may not be aware of the 

presence of either butterfly on their 

lands and that land may not be 

intentionally managed for the 

conservation of the species, but rather 

used in ways that are inadvertently 

favorable to the species. We have 

discussed this issue further in Factor E 

of this final listing rule. In the United 

States, we have notified private 

landowners of most of the sites where 

we believe the species is still present or 

its status is unknown, and many of the 

sites where the species is extirpated or 

possibly extirpated, but where the 

habitat may still be suitable for the 

species. We will continue to focus on 

public awareness and work 

cooperatively with landowners 

following listing. 

(38) Comment: One peer reviewer 

asked for clarification on the reduction 

of Dakota skipper range, specifically 

what was meant by our statement of ‘‘an 

approximately 690-km (430-mi) 

reduction of its range’’ 

Our Response: We have removed this 

phrase from this final listing rule, 

because it was unclear. The Dakota 

skipper is considered to be extirpated 

from Illinois and Iowa and no longer 

occurs in eastern Minnesota. 

Factor A 

(39) Comment: One peer reviewer 

recommended that the date of first 

allowable haying be after July 22, 

because some adult flight has been 

documented after the date of July 16, 

which was our recommendation for the 

earliest haying. Another peer reviewer 

noted that in Manitoba, August 1 is the 

recommended earliest haying date at 

Dakota skipper and Poweshiek 

skipperling sites, although little haying 

is occurring where the Poweshiek 

skipperling is present. Sites should not 

be hayed within 3 to 4 weeks of the 

beginning of the adult flight period to 

prevent destruction of nectar plants. 

While there may be situations in the 

United States where sites undergo 

haying ‘‘no more than every other year,’’ 

most sites in Manitoba are hayed for 

several years in a row, but there are no 

studies on the impact of repeat annual 

haying. 

Our Response: Our categorization of 

stressors as having high, medium, or 

low impacts on the species, and the 

criteria we use to define those 

categories, were developed specifically 

to guide our analysis of the factors 

affecting the species, and are not 

intended as guidelines for conservation 

efforts. Conservation guidelines for the 

Dakota skipper are available (online at 

http://www.fws.gov/midwest/

endangered/insects/dask/

DASKconservationguidelines.html), and 

we are developing similar guidelines for 

the Poweshiek skipperling. In those 

guidelines, we recommend that haying 

activities occur after the adult flight 

period. 

(40) Comment: A peer reviewer asked 

whether, in the grazing section of the 

proposed rule, did the Service mean 

that even when grazing is hard enough 

to eliminate the skipper, the habitat 

potential isn’t completely destroyed, as 

it is by mining or plowing, and can be 

restored? 

Our Response: This is correct, and we 

clarified the language in this rule to 

more clearly state that, unlike habitat 

destroyed by mining or plowing, for 

example, intensely grazed habitat has 

potential to recover or be restored. 

Attempts have been made to restore 

prairie remnants that have been plowed 

or mined (where significant soil 

disturbance has occurred), but such 

restorations have not been successful for 

the Dakota skipper or Poweshiek 

skipperling, at least in observable 

timeframes. 

(41) Comment: A peer reviewer noted 

that the proposal asserts that ‘‘grazing is 

one of the primary treatments for 

controlling smooth brome and 

enhancing native plant diversity in 

prairies that have been invaded by this 

nonnative grass species.’’ The peer 

reviewer stated that the assertion goes 

beyond anything in the cited document 

(Service 2006). There is no supporting 

research for grazing reducing brome, 

while at the same time maintaining or 

improving the native species 

composition. There is, however, support 

for the opposite—that grazing can 

stimulate brome and reduce native 

diversity. Smart et al. (2011) discuss 

grazing as a promising possibility, based 

on inferential, circumstantial, and 

anecdotal information, and the group 

agreed that experimental investigation is 

a big need. More accurately, the citation 

would support this statement: ‘‘grazing 

may be a valuable tool for controlling 

smooth brome invasion and maintaining 

native diversity in prairies, especially 

where circumstances make the use of 

fire difficult.’’ 

Our Response: We clarified the 

statement regarding grazing as a 

potential management tool for invasive 

species control to more accurately 

reflect the proceedings of the Service 

workshop (Service 2006) and Smart et 

al. (2011). Smart et al. (2011) used 

repeated clipping methods to simulate 

intensive early-season grazing and 

discusses the potential for using grazing 

as a tool to improve native prairie under 

certain conditions. 

(42) Comment: One peer reviewer said 

that recent statistics related to habitat 

conversion show that the statement, 

‘‘The economic benefit of grazing to 

ranchers may also benefit the species at 

some sites by deterring conversion of 

remnant prairies to row crop 

agriculture’’ is out-of-date, and said this 

sentence contributes little to the 

argument that remaining habitat is 

secure. 

Our Response: We clarified the 

statement on conversion in this final 

rule to reflect the current economic 

conditions that row crop agriculture is 

generally more economically profitable 

than light grazing. 

(43) Comment: A peer reviewer noted 

that the proposed rule includes little 

discussion of soil compaction as a result 

of grazing. A field demonstration by 

Natural Resources Conservation Service 

(NRCS) staff showed that soil 

compaction on a heavily grazed pasture 

was almost as hard as a brick, and very 

little of the water falling on it soaked in. 

Soil of this character would be quite 

difficult for the larvae of Dakota skipper 

to penetrate for shelter construction, 

causing them to be more exposed to 

predators, parasitoids, and other 

environmental stresses. The Poweshiek 

skipperling would not be affected by 

compaction, as it doesn’t burrow. 

Our Response: We agree that soil 

compaction due to heavy grazing may 

cause the Dakota skipper to be more 

exposed to predators, parasites, and 

other environmental stresses, such as 

fire, than if they were able to build 

underground shelters, and we have 

taken this into consideration in our 

evaluation of the threats to the species. 

(44) Comment: A peer reviewer 

commented that the effects of grazing in 

Manitoba and Saskatchewan, as stated 

in Webster (2007), may not be 

applicable under current population 

scenarios. Even light grazing may be 

detrimental on dry short-grass prairie 

sites prior to and during the adult flight 

period. 

Our Response: We incorporated this 

information into the Factor A threats 

analysis of this final listing rule, below. 

(45) Comment: A peer reviewer stated 

that potash mining, gravel mining, 

flooding, and associated flooding 

protection activities may be significant 

threats to these species in Canada. 


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Our Response: We incorporated this 

information into the Factor A threats 

analysis of this final listing rule, below. 

(46) Comment: One peer reviewer 

recommended that we not include the 

research from an unpublished paper by 

Schlicht (2001a), due to serious flaws in 

the methodology. 

Our Response: Because of serious 

concern over the methods used in this 

unpublished paper, we removed the 

information from Schlicht (2001a) from 

this final listing rule (under Factor A— 

Fire), below. 

(47) Comment: A peer reviewer stated 

that the discussion on threats from fire 

in the proposed rule focuses on 

controlled burns, but wildfires are a 

serious problem in Manitoba and 

previously inhabited sites in 

northwestern Minnesota. Due to the 

highly fragmented nature and 

comparatively small size of sites, 

wildfire may be a greater threat than 

either haying or grazing activities. 

Our Response: We considered 

wildfires to have moderate to high 

impacts to Dakota skipper and 

Poweshiek skipperling populations; the 

impacts would depend on the timing, 

intensity, and extent of the burn. We 

discuss wildfires in Manitoba in the 

Background (population distribution 

and status) section and in Factor E of 

this final rule, and considered that 

fragmentation due to stochastic events, 

such as wildfires, may lead to extinction 

at isolated sites (Factor E). 

(48) Comment: One peer reviewer 

provided a link to the Northern 

Tallgrass Prairie Lepidoptera 

Conservation Conference Working 

Group Reports Synthesis. 

Our Response: We added the 

reference to the discussion regarding 

conservation efforts under Factor A in 

this final listing rule, below. 

(49) Comment: A peer reviewer noted 

that, in the Conservation Efforts To 

Reduce Habitat Destruction, 

Modification, or Curtailment of Its 

Range section of the proposed rule, 

there was reference to a 1995 expert 

panel and plan. The peer reviewer asked 

whether an actual plan was developed. 

Our Response: The group outlined a 

plan for surveying populations and 

characterizing sites and habitats at 

priority areas, identifying and 

recommending management needs, 

monitoring, and outreach and 

education; however, this plan was not 

drafted or finalized. 

(50) Comment: A peer reviewer noted 

that, in a number of incidences within 

the last decade in Canada, sites have 

had general population declines or sites 

have been lost to intense agricultural 

use. 

Our Response: We are aware of four 

sites in Canada where the Dakota 

skipper is now extirpated or possibly 

extirpated due to habitat destruction. 

Only sites where we believed the 

species is currently present or possibly 

present (unknown) were evaluated in 

our threats assessment. 

(51) Comment: One peer reviewer 

provided details on Poweshiek 

skipperling populations following 

prescribed burns in Manitoba (based on 

Dupont 2013). Specifically, Poweshiek 

skipperling populations were most 

numerous in sites burned 5 to 8 years 

previously. The species was absent in 

sites that were burned the previous year, 

in small numbers in areas that were 

burned 2 to 4 years prior, and absent 

from areas that were burned 10 or more 

years before the survey. 

Our Response: We have incorporated 

this information under Factor A of this 

final listing rule, below. 

Factor C 

(52) Comment: One peer reviewer 

provided additional information on 

Wolbachia, a bacteria affecting many 

butterfly species. 

Our Response: We incorporated the 

new information into our discussion on 

Wolbachia under Factor C of this final 

listing rule, below. 

(53) Comment: A peer reviewer 

commented that parasitism, predation, 

and disease may be significant stressors 

to Poweshiek skipperlings and Dakota 

skippers. A hypothesis in the rapid 

decline of the Poweshiek skipperling, 

and possibly the Dakota skipper, is that 

a newly virulent pathogen or a new 

parasitoid has increased mortality above 

normal levels. The small number of 

predation and parasitization events that 

were observed is evidence only of the 

difficultly in documenting such events. 

Dana (1991, pp. 26–27) reported 

observing predation on the butterfly by 

arthropods and large robber flies 

(Asilidae), which are common in upland 

prairie habitats. The peer reviewer also 

cited and discussed several studies that 

pertain to predation on butterflies. 

Our Response: We reviewed the 

McCabe (1981) and Dana (1991) reports 

again and considered additional 

information on the normal population 

dynamics of insects, how these factors 

may explain the rapid decline of the 

Poweshiek skipperling, and perhaps the 

Dakota skipper, and how these factors 

may affect small, isolated populations in 

the future. We cannot conclude with 

certainty that parasitism and predation 

are significant stressors, because these 

occurrences are extremely difficult to 

observe, and only a few studies 

document these events. Therefore, we 

conclude that the level of impact from 

disease, parasitism, and predation is 

uncertain, but do not dismiss the 

possibility that these factors may 

become significant in the future. 

Factor D 

(54) Comment: A peer reviewer 

commented that, in North Dakota, the 

fundamental purpose of management of 

State School lands is economic, not 

scientific or environmental. 

Consequently, if such land does not 

produce income for the State, it may be 

subjected to deliberate change in 

management strategy, including sale at 

auction. The Dakota skipper’s security 

at no fewer than two sites in North 

Dakota, therefore, depends on the 

economic value of hay, because those 

sites are on North Dakota Trustlands 

and are currently under haying 

management. 

Our Response: We have incorporated 

this information into Factor D of this 

final listing rule. 

(55) Comment: A peer reviewer stated 

that the Poweshiek skipperling was 

listed as State-endangered in Minnesota 

on August 19, 2013. 

Our Response: We have updated the 

State status of the Poweshiek 

skipperling in Minnesota in this final 

rule. 

Factor E 

(56) Comment: One peer reviewer 

stated that, although the Service has not 

collected much direct evidence of 

threats to populations of the Poweshiek 

skipperling in North Dakota compared 

to Dakota skippers in the State, it is 

reasonable to assume that the same 

factors that affect the Dakota skipper 

have similarly affected the Poweshiek 

skipperling, because the two species 

share a preponderance of habitat 

characteristics, and often are sympatric 

(have overlapping ranges). 

Our Response: The Service agrees 

with the reviewer’s statement. We also 

think that the reverse is true: It is 

reasonable to assume that Dakota 

skipper may be vulnerable to the factors 

that have caused dramatic declines in 

the Poweshiek skipperling, but perhaps 

with a delay in timing. We consider this 

possibility in our analysis. 

(57) Comment: One peer reviewer 

provided detailed information on the 

size and isolation of Dakota skipper 

sites in central Manitoba. These sites are 

generally greater than 158 ac (64 ha), 

and all are separated by 1 km (0.6 mi). 

Several sites are separated by many 

kilometers (miles). The reviewer also 

suggested that the Service consider the 

implications of the separation of the 

U.S. and Canada sites. 


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Our Response: We have incorporated 

this information, supplemented by 

information in two recently published 

Master’s theses (Dupont 2013, Rigney 

2013a), to update our threats analysis 

for Canadian populations. Although we 

were unsure of the size of many sites in 

Canada, most sites were separated by 

more than 1 km (0.6 mi); therefore, 

approximately 25 of the sites evaluated 

in Canada were thought to be at least 

moderately affected by small size and 

isolation. The Canada sites where 

Dakota skippers are considered to be 

present are approximately 115 km (71 

mi) from the nearest U.S. sites, and the 

Manitoba site is approximately 166 km 

(103 mi) from the nearest Poweshiek 

skipperling site in Minnesota. 

(58) Comment: A peer reviewer noted 

that South Dakota State University 

conducted a climate change analysis, 

with an emphasis on terrestrial habitats, 

in association with the revision of the 

South Dakota Wildlife Action Plan. 

Our Response: We reviewed that 

report and incorporated relevant 

information into Factor E of this final 

listing rule. We will also consider this 

report during recovery planning for the 

two species. 

(59) Comment: One peer reviewer 

queried as to whether either species has 

been evaluated using NatureServe’s 

Climate Change Vulnerability Index 

(https://connect.natureserve.org/

science/climate-change/ccvi)? 

Our Response: The Service has not 

evaluated either species using 

NatureServe’s Climate Change 

Vulnerability Index, but will consider 

using this tool in the recovery phase. 

We used several studies specific to the 

Dakota skipper and Poweshiek 

skipperling, as well as general studies of 

climate-related changes in the Midwest 

and throughout North America. See the 

Climate Change section of this final rule 

for more details on the studies used. 

(60) Comment: A peer reviewer 

suggested that the Service should 

provide more detail on the need for 

future planning, potential dispersal 

corridors, restoration of existing sites, 

and potential reintroduction and 

augmentation sites. The high degree of 

habitat fragmentation and isolation of 

sites combined with the limited 

dispersal ability of these species have 

potential for long-term implications, 

and management actions, even if 

effective in short-term conservation of 

local populations, may not be enough to 

prevent the species from extirpation. 

Our Response: We agree with the peer 

reviewer that detailed planning will be 

needed to recover the Dakota skipper 

and Poweshiek skipperling. The Service 

will begin the recovery planning process 

once the final listing becomes effective. 

(61) Comment: One peer reviewer 

wanted to know how the species would 

be treated for law enforcement 

purposes, in order to ensure that private 

landowners and others that may have 

these species on their land would 

comply with section 9 of the Act. The 

reviewer asked specifically about 

unauthorized collection, handling, and 

possession that could result in a 

violation of section 9 of the Act, as 

listed in the ‘‘Available Conservation 

Measures’’ section of the proposed 

listing rule. The reviewer stated that it 

may be likely that private citizens have 

specimens of these species in their 

possession. 

Our Response: If private citizens hold 

specimens of either species that have 

been collected in the past, they should 

report these specimens to their local 

conservation officer or Service 

enforcement official to receive the 

appropriate documentation that they 

were collected prior to listing. 

Collecting either the Dakota skipper or 

Poweshiek skipperling after they are 

listed would be a violation of section 9 

of the Act, unless the collector held an 

appropriate permit from the Service. 

(62) Comment: One peer reviewer 

noted that the list of nonnative species 

in the ‘‘Available Conservation 

Measures’’ section of the proposed 

listing rule are already well-established 

species. A more meaningful list would 

include species that are not already 

established, to prevent future invasive 

species issues that negatively impact 

these and other native species, and that 

would inform land managers of plant 

selection for grassland or wildliferelated plantings. 

Our Response: We agree that glossy 

buckthorn, reed canary grass, and leafy 

spurge are well established in many 

areas within the range of the species. It 

is still important for landowners to 

know that these nonnative species are 

detrimental to the butterflies and their 

habitat, so they may avoid introducing 

them to additional areas or conduct 

activities that would spread their 

growth. We added purple loosestrife to 

the list of invasive plants as well. 

Purposeful introductions of any of the 

above species would be detrimental to 

the butterflies and their habitats. This 

list is not exhaustive, and other 

nonnative species may be destructive to 

the butterflies or their habitats. 

(63) Comment: A peer reviewer asked 

how the habitats in which the 

Poweshiek skipperling or Dakota 

skipper is known to occur will be 

defined, and whether that information 

will be available to the public, such that 

landowners can comply with section 9 

of the Act. 

Our Response: The Service maintains 

a list of counties that are within the 

current range of the species on publicly 

accessible Web sites. We suggest that 

project proponents contact their State’s 

U.S. Fish and Wildlife Service 

Ecological Services Field Office for 

specific information on their area. The 

species are likely to be present only in 

areas with suitable native-prairie 

habitat, and may be present in nearby 

grass-dominated areas suitable for 

dispersal during the adult flight period. 

Suitable habitats are further described 

in the Background section of this final 

listing rule. 

4(d) Rule 

(64) Comment: A peer reviewer 

suggested that the 4(d) rule should 

exempt take caused by haying only after 

July 22, because the Dakota skipper 

flight period extends until after July 15 

at some sites in some years. 

Our Response: We acknowledge that 

extending the earliest date of haying 

from July 15 to July 22 may further 

minimize the likelihood of adverse 

effects to the Dakota skipper, but we 

will retain the July 15 date for the 

following reasons: First, factors other 

than the date in the 4(d) rule will likely 

play a greater role in determining actual 

haying dates, and those factors are likely 

to cause much of the haying conducted 

in areas where the Dakota skipper 

occurs to be carried out later than the 

July 22 date suggested by the 

commenter. Second, the July 15 date has 

been used for many years in a variety of 

conservation agreements as a date to 

ensure that the effects of haying on 

nesting birds is minimized. It is 

typically included, for example, as a 

required provision in grassland 

conservation easements purchased on 

private lands by the Service. By 

retaining the July 15 date, we minimize 

the likelihood of causing confusion, and 

encourage greater cooperation with our 

conservation partners. Third, even if 

haying is conducted immediately after 

July 15, it may be sufficient to minimize 

adverse effects to Dakota skippers at 

most sites and in most years. Moreover, 

in years when the flight period is 

ongoing past July 15, the Service can 

work voluntarily with landowners and 

land managers to delay haying until the 

flight period is over. 

Comments From Federal Agencies 

(65) Comment: The National Guard in 

North Dakota (NDARNG) commented on 

their concern that training activities on 

the Camp Grafton South (CGS) and 

Garrison Training Area (GTA) will be 


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restricted and that the NDARNG would 

be overwhelmed with new permitting 

and reporting requirements due to the 

listing of the Dakota skipper. The 

NDARNG requested that either Stateowned or federally-owned land that is 

operated and managed by the NDARNG 

be exempt from these proposed rules 

per proposed § 17.47(b)(3) for military 

training conducted on lands covered 

under an Integrated Natural Resources 

Management Plan (INRMP). 

Our Response: Neither the CGS nor 

the GTA was included in the proposed 

critical habitat designation. However, 

according to section 4(b)(B)(iii) of the 

Act, the Department of Defense must 

still comply with section 9 of the Act, 

including the prohibition preventing 

extinction and taking of endangered 

species and threatened species. 

(66) Comment: The NDARNG 

provided additional reports by Fauske 

for surveys conducted in the CGS and 

GTA in 2003 and 2004. The National 

Guard also mentioned surveys that were 

conducted by Fauske in 2013 at those 

locations. Dakota skipper was not 

observed at those sites in those years. 

Our Response: We incorporated the 

data from the 2003 and 2004 reports 

into this final listing rule. We have not 

been able to obtain the data from 

Fauske’s 2013 surveys, but did 

incorporate the National Guard’s claim 

of negative surveys in 2013 into this 

final listing rule. 

(67) Comment: One commenter stated 

that two publications (Grant et al. 2009, 

DeKeyser et al. 2009) that discuss 

management of prairies show that 

sometimes prescriptions for long-term 

management of habitat are at odds with 

short-term management of the species. 

For example, no or light grazing or lateseason haying may lead to invasion of 

cool-season exotic grasses and loss of 

native forb and grasses. Thus no 

management could sometimes be 

considered a threat, just as prairie 

conversion may cause take. 

Our Response: We agree that no 

management or lack of disturbance may 

be a threat to Dakota skipper and 

Poweshiek skipperling habitat and that 

haying, grazing, and fire may be an 

important management tool for these 

butterflies, if carried out appropriately. 

These topics are discussed further in 

Factor A in this final listing rule, below. 

Adaptive management may be necessary 

at many locations to take into account 

the underlying causes of habitat 

degradation and the long-term and 

short-term consequences of management 

to the habitat and the species. We will 

be addressing management at specific 

locations during recovery planning for 

both species. 

(68) Comment: A Federal agency 

commented that some native-prairie 

plant species decrease without proper 

grazing management, and long-term 

monitoring is needed to properly 

examine plant species declines. 

Furthermore, plant species declines may 

be due to other factors, such as 

landscape position, climatic factors, 

historical and current management, and 

other ecological site conditions. Several 

papers cited in the proposed rule 

incorrectly identify forb species that 

decrease due to grazing, such as the 

purple coneflower. 

Our Response: We acknowledge that 

long-term monitoring data would be a 

valuable indicator of important plant 

species declines. Unfortunately, we do 

not have long-term monitoring 

established at most sites; therefore, we 

must rely on the best information 

available. Most references to grazing 

impacts on prairie butterflies are based 

on ancillary observations made during 

research focused on other management 

impacts. Some of these may be 

observational data of changes in site 

conditions at a particular site from one 

year to the next following changes in 

management regimes. We cite a few 

studies that show that certain levels of 

grazing remove nectar sources and are, 

therefore, likely to adversely affect 

Dakota skipper populations (e.g., Rigney 

2013a, pp. 143, 153). We discuss 

grazing, including the effects of grazing 

management in different habitat types, 

further in Factor A of this final listing 

rule, below. 

(69) Comment: A Federal agency 

noted that the proposed listing rule 

states that a large portion of the Dakota 

skipper habitat should remain ungrazed 

or lightly grazed during the adult flight 

period. Management focused on 

preserving every life stage of the 

butterflies will actually lead to their 

demise by inadvertently destroying their 

habitat. 

Our Response: Britten and Glasford 

(2002) recommend minimizing 

disturbance of Dakota skipper habitat 

during the flight period (late June to 

early July) to maximize genetically 

effective population sizes (the number 

of adults reproducing), to offset the 

effects of genetic drift of small 

populations (change in gene frequency 

over time due to random sampling or 

chance, rather than natural selection). 

All life stages are essential to the 

survival of the species, including the 

adult flight stage, which is when 

breeding occurs. Removal of important 

nectar sources during the short adult 

flight period can adversely affect the 

Dakota skipper (e.g., Rigney 2013a, pp. 

143, 153). Thus, it is equally important 

to minimize disturbance of Poweshiek 

skipperling habitat during their adult 

flight period for the same reasons. 

(70) Comment: A Federal agency 

noted that Britten and Glasford (2002, p. 

373), cited in the proposed rule, does 

not identify grazing as a disturbance, as 

the proposed rule indicates. 

Our Response: Although Britten and 

Glasford (2002) did not specifically 

identify grazing as a disturbance, other 

information sources indicate that 

grazing can disturb adult Dakota 

skippers and Poweshiek skipperlings, 

because it may remove important nectar 

sources (e.g., Rigney 2013a, pp. 143, 

153). Both the beneficial and negative 

effects of grazing are further discussed 

in Factor A of this final listing rule, 

below. 

Comments From States 

(71) Comment: A State commented 

that a comprehensive survey effort 

throughout the range of the two species 

is prudent, if not necessary, before any 

listing can occur. 

Our Response: Under the Act, we are 

obligated to use the best available 

scientific and commercial information 

in decisions on whether to list a species. 

In this case, the best available 

information included results from 

surveys, reports by scientists and 

biological consultants, natural heritage 

data, and expert opinion from biologists 

with extensive experience studying the 

Dakota skippers and Poweshiek 

skipperling and their habitats, whether 

published or unpublished. We are 

required to make a decision based on 

that available data. Also, see response to 

comment 76. 

(72) Comment: The Minnesota 

Department of Natural Resources (MN 

DNR) agrees with the Service’s 

conclusion that these species warrant 

protection under the Act and fully 

supports the proposed threatened status 

for the Dakota skipper and the proposed 

endangered status for the Poweshiek 

skipperling. The MN DNR has a long 

history of commitment to the 

conservation of these species and has 

been an active participant in recent 

efforts to assess their status in 

Minnesota. The MN DNR agrees with 

the Service’s conclusions regarding 

factors affecting the species and their 

resulting status. In light of recent 

findings, the MN DNR has reclassified 

both species as endangered under 

Minnesota’s Endangered Species 

Statute, effective August 19, 2013. 

Our Response: We appreciate our 

partnership with MN DNR and their 

supporting comments, and have 

updated the information regarding the 

reclassification of both species under 


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Minnesota’s Endangered Species Statute 

in Factor D of this final listing rule. 

Habitat 

(73) Comment: The North Dakota 

Game and Fish Department suggests that 

the Service use NRCS Ecological Sites of 

North Dakota as a means to describe 

specific potential habitat, rather than 

Type A and Type B habitat as described 

in the proposed rule. The ecological site 

descriptions and transition models 

would help direct the proper grazing 

prescription to promote and achieve the 

plant species composition appropriate 

for the given site and requisites for these 

two butterfly species. 

Our Response: We are considering 

using NRCS ecological site descriptions 

as a tool for managers and others to 

narrow down potential habitat for one 

or both species. However, NRCS 

ecological site descriptions have not 

been developed for all areas where the 

species may be present. For the 

purposes of this final listing, we found 

that Type A and Type B habitat 

descriptions were descriptive of the 

habitat and flowering forbs and grasses 

necessary for the two butterflies. 

(74) Comment: North Dakota 

commented that, based on the specific 

precipitation and evaporation rates of 

Dakota skipper habitat that McCabe 

suggests, the western area of North 

Dakota should not be considered as part 

of the range for the Dakota skipper, as 

those areas do not meet those specific 

rates. 

Our Response: We have determined 

that the Dakota skipper is threatened 

throughout its range, which includes the 

18 counties where the species has been 

documented in North Dakota. The 

Dakota skipper is historically known 

from several counties in western North 

Dakota (e.g., McKenzie, Burke, Montrail, 

and Dunn counties) and is considered to 

be present in at least two locations in 

McKenzie County. The Dakota skipper 

may still occur in areas of western North 

Dakota that may have conditions that 

are different from what McCabe (1981) 

describes for some of the eastern 

counties. See the Background section of 

this final listing rule for a list of 

counties in each State. 

(75) Comment: North Dakota 

commented that it appears that any 

native grassland in North Dakota that 

has not been cultivated is potential 

Dakota skipper habitat. 

Our Response: To more clearly define 

what constitutes Dakota Skipper habitat 

and where take of Dakota skippers may 

occur, the Service developed tools to 

help determine whether the species may 

be present in specific areas, which are 

available on the Internet at https://

www.fws.gov/midwest/Endangered/

section7/s7process/s7guid_

cons.html#dask. We will continue to 

refine these materials to help reduce 

uncertainty as to where Dakota skippers 

may occur. Dakota skippers are present 

on only a subset of native grassland and 

are unlikely to be present in areas where 

key habitat features are lacking. Those 

features are described in the 

Background section of this rule and in 

the materials available on the Internet. 

As we work to conserve Dakota 

skippers, we will provide landowners 

and land managers with information 

that is as accurate and up-to-date as 

possible to describe the areas where the 

species is likely to be present. In 

addition, we will also work with these 

parties to ensure that they understand 

what activities are likely to cause take 

of the species, whether or not the take 

would be exempted under the 4(d) rule, 

and what actions may be implemented 

to conserve the species. 

Population Status and Distribution 

(76) Comment: A State commented 

that surveys appear to be focused on 

repeated visits to sites that were 

previously inventoried, and a systematic 

search for additional sites has not been 

conducted. Furthermore, a few new 

sites have been discovered since 1996 

without such a systematic search for 

new sites, which suggests that many 

new sites may be found with a 

systematic search. Additionally, 

roadside searches for habitat are not a 

scientifically valid method for 

identifying potential habitat. 

Our Response: The search for 

additional locations of both species has 

been conducted using a variety of 

approaches over the years, and potential 

sites have been narrowed down on the 

landscape using topographic and aerial 

maps, State natural heritage habitat 

mapping data, aerial surveys, roadside 

surveys, and other methods. Other sites 

have been surveyed because of a 

proposed project and the known 

potential for suitable habitat in the area 

or proximity to other known locations of 

the butterflies. Many sites are repeatedly 

surveyed to understand long-term 

trends in the presence of the species or 

to quantify other population parameters. 

Although only a small fraction of all 

grassland in North Dakota, South 

Dakota, and Minnesota has been 

surveyed, a significant proportion of the 

un-surveyed area is likely not suitable 

for the species. For example, the species 

was not detected at approximately 108 

additional locations in North Dakota 

that were surveyed for the species in the 

period 1991–2013 (USFWS 2014, 

unpubl. geodatabase). Similarly, in 

South Dakota and Minnesota, 79 and 

148 additional locations, respectively, 

were surveyed for the species in the 

period 1991–2013 (USFWS 2014, 

unpubl. geodatabase). 

Many of these sites have been 

surveyed multiple times over several 

years. Surveys for the Dakota skipper 

are typically conducted only in areas 

that have the particular plant species 

the skipper requires. New potential sites 

surveyed are generally focused on 

prairie habitat that appears suitable for 

the species and has a good potential of 

hosting the species. Therefore, 

researchers have a higher likelihood of 

detecting the species at these sites than 

at sites randomly selected across the 

landscape. Based on these surveys, the 

likelihood that significant numbers of 

undiscovered Dakota skipper 

populations occur in North Dakota, 

South Dakota, or Minnesota is low. We 

acknowledge that there may be some 

undiscovered populations, however, 

and are exploring using spatially 

explicit modeling to develop probability 

occurrence maps of both species, to help 

direct future surveys and conservation 

efforts. 

(77) Comment: Since the Poweshiek 

skipperling has not been detected in 

South Dakota since 2002, South Dakota 

should not be included in the listing 

proposal. Further research needs to be 

conducted to determine if this species is 

present in South Dakota before it is 

listed. 

Our Response: According to our data 

and analysis, the species’ presence is 

unknown at 36 of the total 69 sites 

where the species has been documented 

in South Dakota. The species was 

detected at least once at all 36 of these 

sites in 1993 or later; 19 of these sites 

had positive detections of the species in 

2002 or later. The most recent detection 

of the species in South Dakota was at 

two sites in 2008. Surveys for the 

species were not conducted at any of the 

36 sites with unknown occupancy 

between the years 2007 and 2011, and 

we cannot presume that the species is 

not persisting at a site only because 

there have not been consistent annual 

surveys. At several sites, the species has 

persisted for longer than 20 years; for 

example, the Dakota skipper was first 

recorded at Scarlet Fawn Prairie in 

South Dakota in 1985 and the species 

was detected during every survey since 

that date. Similarly, the Poweshiek 

skipperling was first recorded at 

Waubay National Wildlife Refuge in 

1969 and was recorded during every 

year the site was surveyed through 

2003. South Dakota is in the range of the 

Poweshiek skipperling, and the species 

is listed throughout its range. See our 


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response to comment 76 regarding 

additional surveys or research. 

Factor A 

(78) Comment: A State commented 

that careful implementation of grazing 

and prescribed fire can be an effective 

management tool in prairie remnants. 

The Service should provide clear and 

practical HMGs/BMPs (Habitat 

Management Guidelines/Best 

Management Practices) for acceptable 

use of prescribed fire and grazing 

implementation. 

Our Response: We developed Dakota 

skipper conservation guidelines (http:// 

www.fws.gov/midwest/endangered/

insects/dask/

DASKconservationguidelines.html) that 

address grazing, prescribed fire, weed/

invasive species control, and other 

topics, and are preparing similar 

guidelines for the Poweshiek 

skipperling. While some detail is 

provided in terms of timing, periods of 

rest, and number and size of burn units, 

the Service stresses that effective 

implementation of the conservation 

measures relies on a thorough and 

accurate understanding of the 

distribution and status of the Dakota 

skipper and Poweshiek skipperling and 

their habitat within a management area. 

These two species are likely to be nonuniformly distributed within habitat 

areas (e.g., Rigney 2013a, p. 140). 

Therefore, a species expert should 

frequently assess and map habitat and 

distribution of the species within 

management areas to ensure that 

managers may act based on correct and 

up-to-date information. 

(79) Comment: A State asked whether 

grazing of potential butterfly habitat 

other than low mesic sites will 

constitute take. 

Our Response: Such decisions will 

require site-specific information. If a 

project occurring in potential butterfly 

habitat may affect one or both species or 

its habitat, we suggest contacting the 

Service’s Ecological Service Office in 

your State. 

(80) Comment: A State commented 

that habitat modification and 

fragmentation may be a large threat to 

many grassland species. While other 

factors may need to be addressed to 

protect the species, conversion of 

grasslands is the largest single issue. 

Once land conversions have occurred, 

the land cannot be restored to match the 

specific requirements of these specialist 

species. Listing can be viewed by 

private landowners as an encumbrance 

and a disincentive to conserve 

grassland; hence privately owned 

grassland could be converted, due to the 

current crop commodity environment 

and demand for additional cropland. 

Our Response: We agree that 

conversion of remnant prairies is a 

significant concern. Conversion of land 

to agricultural and other uses is 

discussed in Factor A of this final listing 

rule, below. 

Factor E 

(81) Comment: South Dakota 

commented that, as part of the South 

Dakota Wildlife Action Plan Revision, 

experts at South Dakota State University 

conducted a climate change analysis 

with an emphasis on terrestrial habitats. 

Our Response: The Service 

appreciates this information. We 

reviewed the climate report and 

included information from it into Factor 

E of this final listing rule. This report 

will also help inform recovery planning 

and implementation. 

Economic Concerns 

(82) Comment: A State questioned 

how a private landowner would be 

compensated if, during the course of the 

Service’s activities for monitoring the 

critical habitat areas, the private 

landowner’s land or property is 

damaged. 

Our Response: Surveys for either 

species on private lands would only be 

conducted with landowner permission. 

Surveys for the species and its habitat 

are not destructive in nature and have 

little, if any, impact on the land. 

(83) Comment: North Dakota 

commented that listing these two 

species will add a substantial workload 

relative to highway improvement 

project development, construction, and 

maintenance, due to additional section 

7 consultations with the Service. This 

increased workload could add months 

to project timelines and would cause a 

major and unnecessary disruption to the 

highway and road systems in North 

Dakota. 

Our Response: Although an increased 

workload for section 7 consultations 

may be associated with listing these two 

species, section 4 of the Act requires 

species to be listed as endangered or 

threatened solely on the basis of their 

biological status and threats to their 

existence. Section 7 of the Act requires 

Federal agencies to use their legal 

authorities to promote the conservation 

purposes of the Act and to consult with 

the Service to ensure that effects of 

actions they authorize, fund, or carry 

out are not likely to jeopardize the 

continued existence of listed species. 

During consultation, the action agency 

receives a biological opinion or 

concurrence letter addressing the 

proposed action. In the relatively few 

cases in which the Service makes a 

jeopardy determination, the agency 

offers reasonable and prudent 

alternatives for how the proposed action 

could be modified to avoid jeopardy. 

The Service will work with the 

consulting agency as expeditiously as 

possible to complete the section 7 

consulation process in a timely manner. 

(84) Comment: A State asked, what 

would happen should a private 

landowner incidentally take either 

species during the course of routine 

farming operations on private land. 

Our Response: Under the Act, it is 

unlawful for a person to take a listed 

animal without a permit. Take is 

defined as ‘‘harass, harm, pursue, hunt, 

shoot, wound, kill, trap, capture, or 

collect or attempt to engage in any such 

conduct.’’ Through regulations, the term 

‘‘harm’’ is defined as ‘‘an act which 

actually kills or injures wildlife. Such 

an act may include significant habitat 

modification or degradation where it 

actually kills or injures wildlife by 

significantly impairing essential 

behavioral patterns, including breeding, 

feeding, or sheltering.’’ Section 10 of the 

Act may be used by landowners 

including private citizens, corporations, 

Tribes, States, and counties who want to 

develop property inhabited by listed 

species. Landowners may receive a 

permit to take such species incidentally 

to otherwise legal activities, provided 

they have developed an approved 

habitat conservation plan (HCP). HCPs 

include an assessment of the likely 

impacts on the species from the 

proposed action, the steps that the 

permit holder will take to avoid, 

minimize, and mitigate the impacts, and 

the funding available to carry out the 

steps. HCPs may benefit both 

landowners and the species by securing 

and managing important habitat, and by 

addressing economic development with 

a focus on species conservation. 

We recognize that the Dakota skipper 

and Poweshiek skipperling remain only 

on lands where management has 

allowed them to survive. This is due to 

good land-stewardship, and we want to 

encourage management practices that 

support the butterflies. To minimize 

impacts to landowners and promote 

continued cooperation with them while 

recovering the Dakota skipper, the 

Service developed a 4(d) rule under the 

Act for that species. This 4(d) rule 

exempts incidental take of Dakota 

skippers caused by certain routine 

livestock operations and mowing 

recreational trails. Any ‘‘take’’ that 

results from private landowner activities 

not exempted under the 4(d) rule would 

require a permit from the Service. 

Therefore, private landowners with 


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Dakota skippers on their property 

should become familiar with the 

contents of the 4(d) rule and contact the 

Service if they have questions. Actions 

that may cause ‘‘take’’ and require a 

permit from the Service include 

prescribed burns, haying before the 

adult flight period ends, broadcast 

herbicide treatments, some insecticide 

treatments, and permanent conversion 

of the Dakota skipper’s grassland 

habitats. The 4(d) rule does not apply to 

take of the Poweshiek skipperling 

because it is listed as endangered, and 

the Act does not allow 4(d) rules for 

endangered species. Any activity that 

would result in take of Poweshiek 

skipperlings would first require a permit 

from the Service. 

(85) Comment: A State commented 

that where section 7 consultations will 

be required is unclear. What areas 

would have to be surveyed to determine 

whether the species is present? A large 

amount of potential habitat may need to 

be surveyed during the short adult flight 

period, and there are a limited number 

of qualified entomologists to conduct 

the surveys. 

Our Response: The Dakota skipper 

and the Poweshiek skipperling are both 

closely tied to native-prairie habitats 

and are unable to inhabit areas such as 

nonnative grasslands, weedy roadsides, 

or tame haylands. In addition, these 

butterflies are not likely to inhabit 

reconstructed prairies (e.g., former 

cropland replanted to native-prairie 

species). Therefore, the Service 

recommends that, to determine whether 

a section 7 consultation may be required 

or recommended, action agencies 

should first coordinate with their local 

U.S. Fish and Wildlife Service 

Ecological Services field office and 

provide a description of the area that 

would be affected, directly or indirectly, 

by the proposed or ongoing action. If 

survey data are unavailable or 

inconclusive for the action area, and 

features of Dakota skipper or Poweshiek 

skipperling habitat are predominant in 

at least part of the area, a survey by a 

qualified individual may be 

recommended. The Service is 

developing a list of qualified surveyors, 

which will be available through the 

field offices in each State. 

(86) Comment: North Dakota 

expressed concern that any impact to 

native grasslands in North Dakota will 

be considered take and require an 

incidental take permit. Adjusting the 

timing of construction activities will not 

avoid take because of the species’ 

biology. 

Our Response: The Dakota skipper 

and Poweshiek skipperling historically 

occurred in 18 and 7 counties in North 

Dakota, respectively, and unless the 

species are discovered in additional 

counties, section 7 consultation would 

be required only in those counties and 

on a subset of lands within those 

counties where the species may occur or 

where critical habitat has been 

designated. You may obtain a list of 

counties in which the species may occur 

from the U.S. Fish and Wildlife Service 

Ecological Services field office in your 

State. Furthermore, these two species 

have specific habitat requirements 

(native, unbroken prairies), and it is 

likely that many action areas will not 

contain those types of prairie habitats. 

Therefore, project proponents should 

first provide the field office with a 

description of the area that would be 

affected by the proposed or ongoing 

action to determine whether a section 7 

consultation may be required or 

recommended. See our response to 

comment 85 and the Background of this 

final listing rule for additional 

information regarding the habitats these 

two species inhabit. 

(87) Comment: A State asked whether 

reinitiation under section 7 of the Act 

will need to occur, or will any new 

restrictions be recommended when new 

projects begin or existing projects are 

renewed. 

Our Response: Section 7(a)(2) of the 

Act requires Federal agencies to consult 

with the Service to ensure that actions 

they fund, authorize, permit, or 

otherwise carry out will not jeopardize 

the continued existence of any listed 

species or adversely modify designated 

critical habitat. Therefore, reinitiation of 

section 7 consultations may be required 

for ongoing, new, or revised actions that 

may affect the Dakota skipper or 

Poweshiek skipperling or their 

designated critical habitat. We 

recommend contacting the U.S. Fish 

and Wildlife Service Ecological Services 

field office in your State to determine 

the need for section 7 consultations on 

specific projects. 

(88) Comment: A State asked what 

types of conservation or mitigation 

measures would be needed to offset 

potential impacts to the species or 

designated critical habitat, and how will 

the Service ensure timely approval of 

mitigation measures. 

Our Response: The Service developed 

conservation guidelines for the Dakota 

skipper that are available online 

(http://www.fws.gov/midwest/

endangered/insects/dask/

DASKconservationguidelines.html) and 

is developing similar guidelines for the 

Poweshiek skipperling. We suggest that 

private landowners implement 

applicable guidelines to assist species 

and habitat conservation efforts and 

contact their local Service Ecological 

Services field office if they are planning 

an activity that may affect one of these 

species. For actions with a Federal 

nexus, action agencies should contact 

their local field office to discuss the 

timeliness of our section 7 consultation 

process. For example, from the date that 

formal consultation is initiated, the 

Service is allowed 90 days to consult 

with the agency and applicant (if any) 

and 45 days to prepare and submit a 

biological opinion. Biological opinions 

may include reasonable and prudent 

measures and terms and conditions, 

both intended to minimize the impact of 

incidental take. 

(89) Comment: A State asked whether 

State natural resource agencies be 

expected to restore the species to Stateowned lands where they are considered 

to be extirpated. 

Our Response: The Service will work 

with the State agencies and other 

stakeholders through recovery planning 

to identify areas that would aid in 

recovery of these species, and determine 

appropriate actions to take on those 

lands. 

(90) Comment: A state commented 

that incentive-based voluntary programs 

work well for other species and may be 

a better solution to conserving the 

species than listing and critical habitat 

designations. The State would like to 

provide potential voluntary methods 

and programs to assist and incentivize 

landowners to implement conservation 

measures and practices that enhance 

butterfly habitat. 

Our Response: We appreciate any 

assistance to incentivize landowners to 

conserve these species. Voluntary 

actions can have a significant 

contribution to conservation. If such 

measures are in place when we are 

evaluating a species for listing, we 

consider those measures and how they 

affect the status of the species in our 

determination. The Service’s policy 

regarding voluntary prelisting 

conservation actions (79 FR 42525, July 

22, 2014), encourages voluntary 

conservation actions for non-listed 

species. However, a species may still 

warrant listing if such voluntary actions 

are not in place when we are evaluating 

a species for listing, or if those actions 

are not sufficient to affect the need to 

list a species. We suggest you contact 

the Service’s Ecological Services Field 

Office in your State to discuss voluntary 

conservation programs in detail. 

(91) Comment: A State suggested that 

the Service should develop habitat 

management guidelines and best 

management practices (HMGs/BMPs) in 

close collaboration with State agencies 

and others knowledgeable about 


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effective prairie management. Many 

State-owned prairies are managed with 

the support of Federal funding, and 

HMGs/BMPs are needed immediately in 

order for the State agencies to comply 

with the Act. Such HMGs/BMPs should 

include clear guidance on: Prescribed 

fire; grazing; appropriate use of 

herbicides on occupied sites; pesticide 

buffers around occupied sites and notice 

to landowners adjacent to occupied 

sites; adherence to and enforcement of 

pesticide labels; available tools and 

incentives, including incentives and 

management practices for expanding 

prairie restoration to adjacent restorable 

lands; distinct measures for occupied 

habitat and unoccupied habitat, 

including lands targeted for restoration 

or enhancement; measures for restored 

habitat, and the point at which habitat 

is considered restored; and importance 

of effectiveness monitoring and adaptive 

management practices in ensuring that 

HMGs/BMPs produce the desired 

benefits to the species and their habitat. 

Our Response: We appreciate this 

comment and look forward to working 

with our State partners in implementing 

conservation and providing assistance. 

The Service has developed conservation 

guidelines for the Dakota skipper that 

are available online (http://

www.fws.gov/midwest/endangered/

insects/dask/

DASKconservationguidelines.html) and 

is developing similar guidelines for the 

Poweshiek skipperling. The Dakota 

skipper conservation guidelines 

address: Prescribed fire management, 

grazing, haying and native seed harvest, 

habitat preservation, habitat restoration, 

weed/invasive species control, 

maintenance of genetic diversity within 

populations, and coordinated 

management. The Service looks forward 

to continued collaboration with State 

agencies and other stakeholders to 

further develop and refine these 

conservation guidelines. These 

guidelines will be used as a basis to 

begin a discussion of HMGs/BMPs 

development. 

(92) Comment: A State suggested that, 

if HMGs/BMPs cannot be completed 

before the effective date of the listing, 

the final rule should be delayed until 

the necessary guidance is available. 

Our Response: Section 4(b)(6)(A) of 

the Act establishes that the Service must 

make a final determination as to its 

proposed action within 1 year of 

publishing the proposal, unless there is 

substantial disagreement about the 

sufficiency or accuracy of the available 

data on which that decision is based, for 

which the Service may seek up to a 6- 

month extension. 

4(d) Rule 

(93) Comment: A state suggested that 

the 4(d) rule be expanded to exempt 

take caused by prescribed burns, as it is 

a valuable habitat management tool. 

Our Response: Although we can 

establish general guidelines for 

managers and landowners who are 

planning prescribed burns in Dakota 

skipper habitats, we determined that it 

would not be advisable to broadly 

exempt take caused by burning in the 

4(d) rule. The impacts of prescribed 

fires on Dakota skipper populations 

depend on numerous factors that 

warrant site-specific evaluation, 

including the number, proximity, and 

size of populations in nearby unburned 

areas; fuel loads; timing of the fire; 

likelihood of escape from fire units; and 

post-fire management of unburned 

units. If fires are proposed in areas 

where they are likely to result in take of 

Dakota skippers, individual reviews 

should be conducted to determine 

potential effects to the species. 

(94) Comment: A state suggested that 

the 4(d) rule should specifically exempt 

mowing and haying of road rights-ofway under all jurisdictions (State, 

county, or township). Exemptions 

should apply in the area from the road 

surface to the right-of-way boundary. 

Our Response: We modified the 4(d) 

rule to exempt take of Dakota skippers 

caused by mowing native grassland for 

hay after July 15 within transportation 

rights-of-way. Except for mowing of 

section line rights-of-way and 

recreational trails, the 4(d) rule only 

exempts take of Dakota skippers that 

occurs as a result of mowing or haying 

that is part of routine livestock ranching 

activities. Except for the two specific 

cases mentioned above—mowing 

section line rights-of-way and 

recreational trails—the 4(d) rule does 

not exempt take of Dakota skippers 

caused by mowing that does not 

produce hay for livestock consumption. 

Regardless, the 4(d) rule exempts take of 

Dakota skippers only if the haying is 

carried out after July 15. We also further 

clarified that Dakota skippers do not 

inhabit tame hayland or grassland 

(hayland or grassland planted to, and 

composed primarily of, nonnative grass 

species, such as smooth brome). 

(95) Comment: One commenting 

agency indicated its support for the 4(d) 

rule, but also stated that it does not 

support the exemption of the listed 

activities for purposes other than 

ranching and trail maintenance, and 

requested that the Service clarify that 

the listed activities would not be 

permitted if used for other categories of 

actions. These activities include haying 

and spot application of herbicides to 

control noxious weeds. 

Our Response: In the final 4(d) rule, 

the Service clarifies that take would be 

exempted for certain activities listed in 

the 4(d) rule when carried out in 

relation to routine livestock operations. 

We did, however, also clarify that take 

that occurred as a result of mowing 

native grassland for hay would be 

exempted if conducted after July 15 in 

transportation rights-of-way. 

(96) Comment: A State commented 

that, in the 4(d) rule, only exempting 

spot spraying of weeds is overly 

restrictive. Leafy spurge, for example, 

cannot be effectively controlled at the 

seedling stage by spot spraying. 

Our Response: We understand that 

there may be cases where spot-spraying 

is insufficient to control outbreaks of 

noxious weeds. Frequent herbicide 

applications, however, have been 

associated with reduced diversity of 

native flowering plants in native 

rangelands (e.g., Smart et al. 2011, p. 

184). Therefore, take caused by 

broadcast herbicide applications is not 

exempted by the 4(d) rule. It many 

cases, Dakota skippers may not be 

present in areas where broadcast 

applications are necessary. The Service 

can provide technical assistance to help 

determine whether Dakota skipper may 

be present. If noxious weed control is 

needed where the Dakota skipper is 

likely to be present, the Service will 

work with landowners or land managers 

to identify techniques that avoid take. 

(97) Comment: One commenter 

requested guidance on whether 

prescribed fire and the activities 

described under the 4(d) rule could be 

implemented ‘‘on sites that might have 

historically supported’’ Dakota skipper. 

Our Response: Take of Dakota skipper 

is prohibited under the Act, unless it is 

a specific action that is exempted under 

the 4(d) rule, which applies to all State, 

private, or tribal lands. If an action is 

implemented on a site where the Dakota 

skipper is no longer present, then take 

is unlikely. An action could result in 

take of Dakota skippers at sites where 

the species has been extirpated if key 

habitat features are still present and an 

extant population inhabits a nearby 

area. In those cases, Dakota skipper may 

have reoccupied the site, and we 

recommend coordinating with the 

Service to ensure that a proposed 

activity is not likely to result in take of 

Dakota skippers. 

(98) Comment: One commenter stated 

that the list of counties in which the 

proposed 4(d) rule did not exempt take 

caused by grazing (Eddy, McHenry, 

Richland, Rolette, Sargent, and 

Stutsman) did not directly correspond 


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to the list of counties in which critical 

habitat was proposed (McHenry, 

McKenzie, Ransom, Richland, Rolette, 

and Wells). 

Our Response: We revised the 4(d) 

rule to exempt take caused by grazing 

throughout the range of the species, and 

not limited to certain counties. Thus, 

the final 4(d) rule exempts take of 

Dakota skippers caused by livestock 

grazing on all private, State, tribal, and 

other non-Federal (e.g., county) lands. 

Public Comments 

General 

(99) Comment: A number of public 

comments opposed the listing of the 

Dakota skipper and Poweshiek 

skipperling as federally threatened or 

endangered species, but provided no 

substantive scientific or commercial 

evidence suggesting that listing is not 

warranted. 

Our Response: While we appreciate 

the opinion of all interested parties, the 

Service must base its decision of 

whether to list the Dakota skipper and 

Poweshiek skipperling solely on the 

basis of the best scientific and 

commercial data available. 

(100) Comment: Several comments 

stated that listing these species will 

interfere with private property rights 

and cause economic impacts, such as 

reduction in land values, fines to 

citizens, prohibitions to development, 

wasteful use of taxpayer money, and 

intrusion to grazing and farming 

operations. 

Our Response: For listing actions, the 

Act requires that we make 

determinations ‘‘solely on the basis of 

the best available scientific and 

commercial data available’’ (16 U.S.C. 

1533(b)(1)(A)) regarding the status of the 

species. Therefore, we do not consider 

any information concerning potential 

economic or other possible impacts 

when making listing determinations. We 

will work with entities to conserve the 

butterflies and develop workable 

solutions. Furthermore, in this rule, we 

have included a 4(d) rule for the Dakota 

skipper that exempts take from certain 

routine grazing activities. The presence 

of a listed species does not give 

government employees or 

representatives any rights to access 

private property. 

(101) Comment: A commenter stated 

that the Service did not use the best 

available science in the proposal. There 

is a lack of evidence to justify the 

proposed actions. 

Our Response: The comment did not 

provide details on what scientific 

information we failed to consider in our 

proposal. In preparation of the proposal 

and this final rule, we used the best 

available scientific and commercial 

information of which we are aware. We 

sought comments from independent 

peer reviewers to ensure that our 

determination is based on scientifically 

sound data, assumptions, and analysis. 

The peer reviewers stated that our 

proposed rule was based on the best 

available scientific information. 

Additionally, the results of 2013 surveys 

conducted throughout the range of both 

species in the United States and 

information from recently published 

research conducted in Saskatchewan 

and Manitoba were considered in our 

final listing rule. 

(102) Comment: A commenter stated 

that listing under the Act and critical 

habitat designations are intertwined and 

cannot be separated, as the Service has 

done with these proposals. 

Our Response: When a species is 

proposed for listing as endangered or 

threatened under the Endangered 

Species Act (Act), we must consider 

whether there are areas of habitat we 

believe are essential to the species’ 

conservation. The listing determination 

and critical habitat determination for 

the Dakota skipper and Poweshiek 

skipperling were conducted at the same 

time and in coordination with each 

other. The proposed rules for each 

action were published on the same date, 

but in separate documents. We are 

currently working to finalize the critical 

habitat determination for these two 

species, which will be published 

shortly. 

(103) Comment: A commenter 

requested that we clarify the status that 

is proposed for each species, as it is 

confusing which is proposed as 

threatened and which as endangered. 

Our Response: The Dakota skipper is 

listed in this rule as a threatened 

species, and the Poweshiek skipperling, 

as an endangered species. 

(104) Comment: A commenter 

requested that the listing and critical 

habitat designations for these species 

will create an adversarial atmosphere 

between the Service and the agricultural 

community, and punish producers, who 

are the best stewards of habitat for a 

variety of species. 

Our Response: We based our listing 

decisions on the basis of biological 

information and have determined that 

the Dakota skipper is threatened and the 

Poweshiek skipperling is endangered 

under the Act. The Service is committed 

to working with private landowners, 

public land managers, conservation 

agencies, nongovernmental 

organizations, and the scientific 

community to conserve the Dakota 

skipper and Poweshiek skipperling and 

their habitats. For example, in 

recognition of efforts that provide for 

conservation and management of the 

Dakota skipper and its habitat in a 

manner consistent with the purposes of 

the Act, we developed a 4(d) rule that 

outlines the prohibitions, and 

exceptions to those prohibitions, 

necessary and advisable for the 

conservation of the Dakota skipper. We 

believe that exempting incidental take 

of Dakota skippers that may result from 

grazing in certain geographic areas will 

afford us more time to protect the 

species’ habitats in these areas and will 

facilitate the coordination and 

partnerships needed to recover the 

species. 

(105) Comment: The North Dakota 

Stockman’s Association commented that 

they have policy supporting the use of 

sound science in decisionmaking. Much 

of the science used to develop these 

proposals was not peer-reviewed or 

published, and was largely based on 

internal documents. The Service’s own 

‘‘Information Standards Under the 

Endangered Species Act’’ policy calls 

for ‘‘review of all scientific and other 

information used by the Services to 

prepare biological opinions, incidental 

take statements, and biological 

assessments to ensure that any 

information used by the Services to 

implement the Act is reliable, credible, 

and represents the best scientific and 

commercial data available.’’ Sound, 

peer-reviewed science needs to be the 

foundation of any proposal, but 

particularly of those with such serious 

implications for citizens. 

Our Response: Under the Act, we are 

obligated to use the best available 

scientific and commercial information, 

which in this cased included results 

from surveys, reports by scientists and 

biological consultants, natural heritage 

data, and expert opinion from biologists 

with extensive experience studying the 

Dakota skipper and Poweshiek 

skipperling and their habitats, whether 

published or unpublished. The Service’s 

databases were also referenced several 

times within the document (e.g., Service 

2014, unpublished geodatabase). These 

databases were built using hundreds of 

sources, including unpublished reports, 

published papers, and State heritage 

data. We referenced these databases in 

the proposed and final listing 

document, in places where we 

summarized data across many sources. 

All of the reports utilized in these 

databases are publically available, upon 

request. 

Additionally, we sought comments 

from independent peer reviewers to 

ensure that our determinations are 

based on scientifically sound data, 


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assumptions, and analysis. We solicited 

information from the general public, 

nongovernmental conservation 

organizations, State and Federal 

agencies that are familiar with the 

species and their habitats, academic 

institutions, and groups and individuals 

that might have information that would 

contribute to an update of our 

knowledge of the species, as well as the 

activities and natural processes that 

might be contributing to the decline of 

either species. The existing body of 

literature on the Dakota skipper and 

Poweshiek skipperling, including 

results from surveys, reports by 

scientists and biological consultants, 

natural heritage data, and expert 

opinion from biologists with extensive 

experience studying the Dakota skipper 

and Poweshiek skipperling and their 

habitats, whether published or 

unpublished, is the best available 

information. 

(106) Comment: A commenter noted 

that the Dakota skipper listing priority 

number indicating threats of moderate 

to low magnitude. 

Our Response: The Service believes 

that the Dakota skipper warrants 

protection under the Act, as a 

threatened species, as discussed in 

detail in this final listing rule. The 

listing priority number was changed 

from 11 to 8 on December 6, 2007 (72 

FR 69034), and the Dakota skipper 

remained a candidate species with a 

listing priority number of 8 in 

subsequent notices through October 26, 

2011 (76 FR 66370). The listing priority 

numbers range from 1 to 12, indicating 

the relative urgency for listing plants or 

animals as threatened or endangered. 

The criteria used to assign this number 

reflect the magnitude and immediacy of 

threat to the species, as well as the 

relative distinctiveness or isolation of 

the genetic material they possess. This 

latter criterion is applied by giving a 

higher priority number to species that 

are the only remaining species in their 

genus, and a lower priority number to 

subspecies and varieties. The listing 

priority number assigned to a species, 

however, does not necessarily reflect the 

classification the Service ultimately 

determines is appropriate for a species 

when making a listing determination, as 

new information may become available 

that affects that decision. 

(107) Comment: A commenter 

questioned how this listing would 

adversely affect other species. 

Our Response: We are unaware of any 

adverse effects that these listings would 

have on other native species of plants or 

animals. Nonnative or invasive plant 

species and species of woody plants 

encroaching into prairie habitats may be 

managed to maintain or increase the 

quality of native-prairie habitats. 

(108) Comment: Commenters asked 

whether those who are enrolled in the 

Conservation Reserve Program, 

Environmental Quality Incentive 

Program, or other U.S. Department of 

Agriculture programs would be subject 

to special requirements. How will the 

listing affect those who have Federal 

crop insurance, have received a Federal 

loan or Federal disaster assistance, or 

own property that has a Federal 

easement? If a landowner is required to 

seek consultation before requesting 

Federal funding or authorization for an 

action that may affect a listed species or 

critical habitat, what cost will be 

involved, both in terms of money and 

time? Will this be reflected in the 

economic impact analysis the Service is 

preparing? 

Our Response: Proposed projects in 

areas where one or both species may be 

present or on designated critical habitat 

that has a Federal nexus (in other 

words, funded, authorized, or carried 

out by a Federal agency) will be 

required to undergo consultation with 

the Service under section 7 of the Act. 

In such cases, it is the responsibility of 

the Federal agency involved to complete 

the consultation. In those instances, the 

action agency should contact the 

Service’s Ecological Services Office in 

their State if they are planning an 

activity that may affect the species or its 

critical habitat. For more information 

about section 7 consultations, visit the 

Service’s Web site (http://www.fws.gov/ 

endangered/what-we-do/consultationsoverview.html). In accordance with the 

Act, we cannot consider possible 

economic impacts in making a listing 

determination. However, section 4(b)(2) 

of the Act states that the Secretary shall 

designate and make revisions to critical 

habitat on the basis of the best available 

scientific data after taking into 

consideration the economic impact, 

national security impact, and any other 

relevant impact of specifying any 

particular area as critical habitat. 

(109) Comment: One commenter 

recommended that better 

documentation is needed when 

Landowner Incentive Program grants or 

other government funding is used. 

Our Response: Government-funded 

grant accomplishment reports are 

typically available online. Information 

on our grant programs available to aid 

species recovery can be found at 

http://www.fws.gov/grants. 

(110) Comment: Private landowners 

who are participating in the Service’s 

recovery program for the Karner blue 

butterfly commented that private 

landowners are critical to the protection 

of endangered and threatened species. 

Private landowners often provide 

suitable ‘stepping stone’ habitat 

otherwise unavailable to public 

agencies. The Federal status of the 

Karner blue butterfly facilitated habitat 

improvements and public awareness 

that may not have occurred but for the 

protection of that species. The 

commenter believes that listing the 

Dakota skipper and Poweshiek 

skipperling will similarly benefit these 

two species. 

Our Response: We thank you for your 

comment and participation in species 

recovery efforts. The Service 

understands the importance of private 

landowner participation and support in 

recovery of the Dakota skipper and 

Poweshiek skipperling and will 

continue to work with all stakeholders 

to this end. 

(111) Comment: One commenter 

expressed disappointment with the 

Service stating that other Service 

projects that are of great benefit to 

society, the commenter did not believe 

that listing the butterflies was one of 

them. The commenter questioned why 

these two butterflies are of such 

importance that they should be listed. 

Our Response: In the preamble to the 

Endangered Species Act of 1973, 

Congress recognized that endangered 

and threatened species of wildlife and 

plants ‘‘are of esthetic, ecological, 

educational, historical, recreational, and 

scientific value to the Nation and its 

people.’’ In this statement, Congress 

summarized convincing arguments 

made by scientists, conservationists, 

and others who are concerned by the 

disappearance of unique creatures. The 

Service is responsible for implementing 

the Act, and as such, must determine 

whether any species is an endangered or 

threatened species, based on the best 

scientific and commercial data available 

regarding the status of that species, not 

based on a certain benefit to society or 

importance. 

Although the Service does not 

consider the value of a particular 

species when making a listing 

determination, these butterflies are 

important and do provide a societal 

benefit. Humans depend on the variety 

of life for food, clothing and medicines. 

When we lose species we lose their 

potential for the future and we lose their 

effect on other species which, in turn, 

have ecosystem roles and future value. 

Continued degradation of our lands and 

waters that reduces our biological 

diversity—the variety of life—is 

important. Habitat and water 

degradation, and maybe even climate 

change, can be reversed, but the loss of 

a species and its genes are irreversible. 


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Further, the prairie ecosystem is not 

completely gone, yet, but it will be if we 

do not take measures to save its plants 

and animals. Protecting these small 

butterflies means protecting their 

habitats, so that some of this ecosystem, 

with all its variety of life, remains. 

Humans depend on the variety of life for 

food, clothing and medicines. The 

variety of life that we have in this 

country, including functioning 

ecosystems, is our natural heritage. 

(112) Comment: One commenter 

stated that change, both desired and 

undesired, is a natural part of the 

evolutionary cycle. 

Our Response: Although extinctions 

occur naturally, scientific evidence 

strongly indicates that the current rate 

of extinction is much higher than the 

natural or background rate of the past. 

The main force driving this higher rate 

of loss is habitat loss. Over-exploitation 

of wildlife for commercial purposes, the 

introduction of harmful exotic 

(nonnative) organisms, environmental 

pollution, and the spread of diseases 

also pose serious threats to our world’s 

biological heritage. None of these 

creatures exists in a vacuum. All living 

things are part of a complex, often 

delicately balanced, network called the 

biosphere. The earth’s biosphere, in 

turn, is composed of countless 

ecosystems, which include plants and 

animals and their physical 

environments. No one knows the 

myriad ways the extinction of organisms 

will affect the other members of its 

ecosystem, but the removal of a single 

species can set off a chain reaction 

affecting many others. Furthermore, 

many individual species are uniquely 

important as indicators of 

environmental quality. The rapid 

decline of the Poweshiek skipperling 

and Dakota skipper may be an indicator 

of a greater environmental problem. 

Regardless of the reason for the species’ 

decline, it it meets the definitions of a 

threatened or endangered species under 

the Act, we are obligated list it under 

the Act. 

(113) Comment: A commenter noted 

that prairie ecosystems are one of the 

most endangered ecosystems of the 

world. Currently only 4 percent of 

remnant tallgrass prairie remains in the 

United States, and the loss in habitat 

has led to the declines in the Poweshiek 

skipperling and Dakota skipper. 

Furthermore, these two species play an 

important role in the prairie ecosystem, 

and by protecting them, we also protect 

other prairie plants and animals. 

Our Response: Native tallgrass and 

mixed-grass prairies have been reduced 

by 85 to 99.9 percent of their former 

area throughout the historical range of 

both species (Samson and Knopf 1994, 

pp. 418–419). Even further destruction 

of remnant prairies has occurred since 

Samson and Knopf’s study. Conversion 

is discussed in Factor A of this final 

listing rule, below. 

(114) Comment: A commenter stated 

that the limits and prohibitions on land 

uses like grazing and haying that are a 

result of this listing will negatively 

affect livestock producers. For example, 

the areas in North Dakota within the 

range of the butterflies are significant 

beef-producing counties. Limiting 

grazing or haying on those lands will 

have serious economic ramifications for 

the cattle-ranching landowners. Because 

of the terrain, some of these lands are 

suited only for livestock grazing. If those 

lands cannot be used for that purpose, 

their value will largely be diminished. 

Under the Service proposals, six North 

Dakota counties are deemed too 

sensitive for grazing, and it appears that 

grazing will be prohibited there 

altogether. 

Landowner concerns about 

compliance could influence those 

impacted to convert their grass and 

haylands to other uses before a final rule 

is in effect. This would be detrimental 

to both the livestock industry and the 

butterflies the Service is aiming to 

protect. 

Our Response: Through public 

meetings, meetings with private 

landowners, and outreach efforts, the 

Service has attempted to reduce the 

concerns of private individuals. It is 

important for private individuals to 

know that only those projects or actions 

that occur in areas where the butterflies 

may be present or on designated critical 

habitat and that have a Federal nexus 

(in other words, funded, authorized, or 

carried out by a Federal agency) must 

undergo consultation with the Service 

under section 7 of the Act. In such 

cases, it is the responsibility of the 

Federal agency involved to complete the 

consultation. We suggest that private 

landowners contact their local Service 

Ecological Services Office if they are 

planning an activity with a Federal 

nexus that may affect the species or its 

critical habitat. For more information 

about section 7 consultations, visit the 

Service’s Web site (http://www.fws.gov/ 

endangered/what-we-do/consultationsoverview.html). Under the 4(d) rule for 

the Dakota skipper, take of Dakota 

skippers caused by certain routine 

livestock operations on all non-Federal 

lands is exempt from the prohibitions 

under section 9 of the Act. For more 

information on the 4(d) rule for the 

Dakota skipper, refer to the Provisions 

of the 4(d) Rule for the Dakota Skipper 

section of the preamble to this final rule. 

(115) Comment: A commenter stated 

that livestock owners are the original 

stewards of this land and other natural 

resources, and the general management 

practices utilized by these owners are 

ecologically sound and enhance the 

productive capabilities of the land. 

These practices may even be enhancing 

the habitat for these two butterflies. As 

private landowners and stewards of 

livestock, land, and other natural 

resources, we look for policies that 

allow coexistence and do not threaten 

our livelihood. 

Our Response: We appreciate your 

comment. Landowners deserve great 

credit for their land stewardship, and 

we want to continue to encourage those 

management practices that support the 

butterflies. The Service also strives to 

find ways to work with people while 

protecting imperiled species. To this 

end, the Act allows for some flexibility 

for species that are listed as threatened; 

the Service is able to tailor the 

protections of the Act to what it deems 

as necessary and advisable to provide 

for the conservation of such species. We 

have developed a 4(d) rule for the 

Dakota skipper that provides for the 

conservation of the species while 

allowing some flexibilities for 

landowners. This 4(d) rule exempts 

incidental take of Dakota skippers that 

is caused by certain routine livestock 

operations and mowing of recreational 

trails. For more information on the 4(d) 

rule for the Dakota skipper, refer to the 

Provisions of the 4(d) Rule for the 

Dakota Skipper section of this final rule, 

below. 

Biology and Habitat 

(116) Comment: A commenter stated 

that the Service is correct to rely on 

Royer et al. (2008) for understanding 

and describing Dakota skipper habitat. 

Dakota skipper data in Minnesota are 

overwhelmingly attributable to Type B 

(upland prairie: Dry-mesic or dry). 

However, type A and B habitats can 

blend into each other. As correctly 

described by the Service here, upland 

and lowland prairie are often 

intermixed in both habitat types (A and 

B). 

Our Response: We describe prairie 

types as Type A or Type B habitat, but 

realize that the two habitat types may be 

intermixed, there may be smaller 

patches that may be better categorized, 

or specific microhabitats that the 

species uses at various times to fulfill 

their biological needs. 

Occupancy 

(117) Comment: A commenter stated 

that the definition of occupancy is 


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difficult to understand and should be 

clarified. 

Our Response: We clarified the 

definition of occupancy in this final rule 

by adding language that clarifies that the 

three sequential years of negative 

surveys necessary to consider the 

species extirpated from a site could be 

from any survey year. We also clarified 

that the occupancy status of an 

extirpated site would not change unless 

the species was detected at that location 

during future surveys. We strove to be 

as accurate as possible in defining 

occupancy for the purposes of the 

listing and critical habitat 

determinations. If you are unsure 

whether either species may occur on 

your property, we suggest you contact 

the Service’s Ecological Services Field 

Office in your state. 

(118) Comment: A commenter stated 

that the Service’s methodology for 

classifying occupancy is well supported. 

Given the difficulties of detecting these 

small butterflies most observable in the 

brief period per year when it is in the 

adult life stage, a conservative approach 

is justified. The timing of the adult 

flight period and the species’ abundance 

varies greatly among years, due to 

climatic variation. At least 3 years of 

surveys are needed before an area 

should be considered extirpated. 

Furthermore, those 3 years of surveys 

need to be detailed efforts per survey, 

with multiple dates of surveys per year. 

Our Response: We appreciate your 

comment in support of our occupancy 

rationale. We agree that multiple dates 

of surveys per year are desired to verify 

non-detection of the species in a given 

year. We have added language to clarify 

that point in the Background section of 

this final listing rule, above. 

(119) Comment: A commenter stated 

that the determinations to list these two 

butterflies are based on historical 

declines, although significant 

documentation of butterfly fauna did 

not occur until 1960, and it is, therefore, 

impossible to determine anything about 

the historical range or any possible 

historical declines. How are past 

declines relevant to the species now, 

and why is the Service listing these 

species now, as opposed to when those 

declines were occurring? It is not 

possible to characterize the magnitude 

of threats to these species without 

knowing what has caused the historical 

decline and understanding what 

constitutes natural levels of inter-annual 

population fluctuation. 

Our Response: We consider historical 

declines, and the ongoing effects of 

those historical declines, as well as 

current and recent declines, in our 

determinations. Significant population 

declines have occurred in both species 

very recently and are still ongoing, and 

the effects of historical declines 

continue to impact both species today. 

Populations that were historically 

fragmented by habitat destruction 

continue to be isolated from one 

another, which may have negative 

genetic consequences or increased 

vulnerability to stochastic events, for 

example. 

Population Status and Distribution 

(120) Comment: A commenter stated 

that the survey methods are inadequate 

and poorly described. In particular, it 

appears that a high percentage of survey 

sites are in close proximity to roads. 

These sites may be disturbed sites, and 

some literature indicates Dakota 

skippers do not occupy formerly 

disturbed and subsequently restored 

sites. 

Our Response: As described in the 

Background section of this final listing 

rule, above, Dakota skippers occupy 

native-prairie sites that have never been 

plowed. During the adult flight period, 

it is possible that Dakota skipper may 

use lesser quality grassland dominated 

areas to travel (disperse) from one 

native-prairie site to another nearby 

native-prairie site. Surveys were 

conducted using various protocols (for 

example, Pollard walks (Pollard 1975), 

modified Pollard walks, wandering 

transects, and timed transects) 

depending on the objective of the 

survey, funding, or available resources 

and staff. Describing the details of 

survey methods for each site is beyond 

the scope of this rule, however, those 

details are described in the survey 

reports that are cited within this final 

rule. We added some brief examples of 

commonly used survey methodologies 

in the Background section of this final 

listing rule. 

(121) Comment: A few commenters 

suggested that there are multiple 

approaches to interpreting data and 

conducting trend analyses. One such 

suggested approach is to use the 

concepts of Schlicht et al. (2009, Table 

10, p. 439) and Swengel and Swengel 

(2012b, Table 2). The observed timing of 

population declines may differ 

depending on the approach used. As 

such, the commenter cautions that the 

information included in Figures 1 and 2 

of the proposed listing rule should be 

interpreted carefully, and provides 

specific suggestions for an alternate 

approach. 

Our Response: We acknowledge that 

there are other ways to look at the data 

and the approach suggested by the 

commenter would be a good way to 

determine the apparent disappearance 

(either absence or undetectable levels) 

of a species at each particular site. 

These types of analyses may be an 

appropriate approach for recovery 

planning and implementation, and we 

will consider their utility at that time. 

We believe the way we interpreted the 

data in the listing rule is appropriate for 

looking at the overall trends in 

detections and non-detections of the 

species through the years across all of 

the known sites, without relying on the 

numbers of individuals observed at each 

site during each survey year, since we 

often do not have those data. Although 

many of the skipper sites have been 

surveyed over multiple years, the 

frequency and type of surveys varied 

among, and sometimes within, sites and 

years. Surveys may have been 

conducted using various protocols and 

with varied objectives and, therefore, 

had varying results. For instance, some 

surveys focused simply on documenting 

species presence while others 

documented the numbers observed in a 

certain area, distance, or period of time. 

Whether or not the species was detected 

in a given year is the only common 

result of all the surveys, so that is the 

data we used to evaluate trends through 

time. 

(122) Comment: One private citizen 

commented that he has never observed 

the Dakota skipper and the Poweshiek 

skipperling on his property or anywhere 

else. 

Our Response: Dakota skippers and 

Poweshiek skipperlings have a single 

adult flight period per year that 

typically occurs from the middle of June 

through the end of July. The actual 

flight period varies somewhat across the 

range of each species and can also vary 

significantly from year-to-year, but 

typically lasts 2 to 4 weeks. Both the 

Dakota skipper and Poweshiek 

skipperling are small and cryptic 

species. Therefore, it is unlikely 

someone will observe these two species 

unless they are actively searching for 

the species in suitable habitat within 

their ranges during the short adult flight 

period. The likelihood of observing 

these species recently is low, because 

these two species have reached 

undetectable levels, even by 

experienced observers, at most of their 

known locations. 

(123) Comment: One commenter 

recommended that surveying and 

monitoring protocols be developed for 

the two species. 

Our Response: Because the objectives 

of surveys may vary across the range of 

these species, we recommend contacting 

the Service’s Ecological Services Field 

Office in your State to discuss the 

appropriate survey protocol to use for 


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particular projects, habitat types, and 

geographic areas. To facilitate effective 

cooperation among agencies, 

organizations, and individuals 

interested in the distribution of these 

species, the Service will maintain a list 

of individuals who meet certain 

qualifications for conducting reliable 

surveys for the target species. 

(124) Comment: One commenter 

provided results from butterfly surveys 

conducted for the past 19 years (1995– 

2013) in Clay and Polk counties, 

Minnesota. Low numbers of Dakota 

skippers were observed in 1996, 2006, 

2007, and 2010. The Poweshiek 

skipperling was observed in 1997–2002, 

2004–2006, and two individual 

Poweshiek skipperlings were observed 

in 2013. 

Our Response: We appreciate 

receiving the new information on 

Dakota skipper and Poweshiek 

skipperling occurrences in Minnesota. 

We verified the information with 

Minnesota Department of Natural 

Resources staff (a qualified surveyor), 

who confirmed the validity of the data. 

We confirmed that the individual was 

capable of identifying the Poweshiek 

skipperling and that the 2013 

observations were valid. This 

information was incorporated into this 

final listing rule. The Service has 

prioritized the Polk County location for 

surveys in future years. 

(125) Comment: A commenter noted 

that the Service included two graphs 

indicating a decline in Dakota skipper 

sites in Minnesota and South Dakota, 

but did not include a graph for North 

Dakota. The 2012 abstract by Royer 

indicates that ‘‘essentially the same 

proportion of count locations hosted 

detectable Dakota skipper populations 

. . .’’ in 1996, 1997 and 2012, but that 

the encounters per hour had decreased. 

The commenter contend that fewer 

‘‘encounters per hour’’ could be the 

result of many factors, including the 

very specific conditions necessary to do 

an accurate sampling. The summary 

data does not provide the necessary 

background to determine other factors 

that could have influenced the 

‘‘encounters per hour’’ count. 

Our Response: The detection versus 

non-detection data for Dakota skippers 

in North Dakota produced no clear 

trend. If we examine years with more 

than 10 sites surveyed, for example, we 

find that in 1991, the species was 

detected at 19 of the 31 sites surveyed 

(61 percent); in 1995, the species was 

detected at 5 of the 10 sites surveyed (50 

percent); in 1996, the species was 

detected at 13 of the 18 sites surveyed 

(72 percent); in 1997, the species was 

detected at 10 of the 25 sites surveyed 

(40 percent); in 1998, the species was 

detected at 11 of the 17 sites surveyed 

(65 percent); and in 2012, the species 

was detected at 15 of the 27 sites (56 

percent) surveyed (where the species 

had previously been observed). Royer 

(2012) was correct that the proportion of 

sites with detections versus nondetections of Dakota skippers were 

similar (e.g., statewide proportions in 

1996 (72 percent), 1997 (40 percent), 

and 2012 (56 percent)). Therefore, we 

examined the results of sites that Royer 

(2012) surveyed using methods that 

quantified results such that they could 

be compared among years. 

Royer used the same survey protocol, 

timed transect searches (where the 

number of individuals observed per 

hour were recorded), for the surveys 

conducted in 1996–1997, 1998, and 

2012 (Royer 1997, Royer and Royer 

2012b). Furthermore, Royer’s 1996, 

1997, 1998, and 2012 surveys (Royer 

1997, Royer and Royer 2012b) adhered 

to our acceptable survey standards (e.g., 

wind speeds, time of day). Therefore, 

the variation in numbers observed 

attributable to survey error is expected 

to be negligible. Average encounter 

frequencies observed across the State in 

2012 (10.7 encounters per hour) were 

lower than during the 1996–1997 and 

1998 statewide surveys (North Dakota 

State average = 16.94 encounters per 

hour and 22.67 encounters per hour, 

respectively). At the site level, sites 

surveyed in 1996–1997 or 1998 

generally had higher numbers of Dakota 

skippers encountered per hour than in 

2012. 

(126) Comment: A commenter stated 

that the proposed listing of the Dakota 

skipper as a threatened species is 

unwarranted at this time. In North 

Dakota, surveys show that essentially 

the same proportion of locations had 

detectable levels of Dakota skipper in 

1996–1997 (46 percent) as in 2012 (46 

percent). Additionally, new sites have 

been discovered in North Dakota, even 

though a systematic survey has not been 

conducted. A substantially lower 

encounter rate in 2012 compared to 

historical surveys was reported, but one 

year of data does not justify listing. 

Our Response: Although the 

proportion of sites surveyed with 

positive detections of the species is 

similar when comparing sites surveyed 

in North Dakota in 1996–1997 with 

those surveyed in 2012, the numbers of 

individuals observed recently were 

substantially lower than in previous 

surveys; see our response to Comment 

125. In addition to the survey data and 

population trend information, the 

Service also considers listing species 

based on an analysis of threats, 

described in detail in this final listing 

rule. The results of that threat analysis 

indicates that all of the Dakota skipper 

sites where the species is considered to 

be present or unknown in North Dakota 

have one or more documented threat of 

moderate to high levels. At least one 

moderate- to high-level threat is 

documented in all Minnesota, North 

Dakota, South Dakota, and Canada 

Dakota skipper sites with present or 

unknown occupancy. 

(127) Comment: A commenter stated 

that the Service rightly states that most 

Poweshiek skipperling decline likely 

went unrecorded because most prairie 

destruction occurred prior to 1960, but 

most prairie butterfly surveys post-date 

those declines. Most decline during 

1960–2000 also went largely 

undocumented. This is evidenced by 

the large number of sites in Minnesota 

that fall into an uncertain occupancy 

category. Longer term Poweshiek 

skipperling decline has been masked by 

data paucity and turnover in sites 

surveyed. 

Our Response: We agree that there is 

a paucity of data at many sites in recent 

years (1960–1993). However, most 

Poweshiek skipperling sites and Dakota 

skipper sites have been surveyed at least 

once in 1993 or more recently. The lack 

of surveys at a given site since 1993 

does mean that we are uncertain of the 

occupancy at many sites. We used a 

cautious approach; by assigning sites 

unknown status, we cannot say that the 

species is truly absent or extirpated 

from a site, while acknowledging that 

the species may still be present, 

possibly at undetectable levels, if 

suitable habitat is still present. More 

surveys are needed at these sites to 

determine if the species is present. 

(128) Comment: A commenter stated 

that, at the time of Swengel’s (1992) 

review, Poweshiek skipperlings had 

fewer known populations, were more 

highly concentrated in preserves (a 

single kind of ownership and land use 

category), were in a narrower range, 

were more concentrated in a highly 

destroyed ecosystem (tallgrass prairie), 

and had a worse immediate response to 

typical preserve management (fire) than 

Karner blue butterflies, which were 

federally listed in 1992. Poweshiek 

skipperlings are capable of high local 

abundance in a few sites, but these 

population numbers are highly volatile, 

and so extremely low numbers also 

occur during these abundance 

fluctuations. Compared to Dakota 

skipper incidence within Poweshiek 

skipperling range, Poweshiek 

skipperlings occurred on relatively more 

preserves, but Dakota skippers had a 

range further west, including mixedVerDate Sep<11>2014 17:13 Oct 23, 2014 Jkt 235001 PO 00000 Frm 00040 Fmt 4701 Sfmt 4700 E:\FR\FM\24OCR2.SGM 24OCR2

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grass prairie, less of which has been 

destroyed. Also, the Dakota skipper is 

more compatibile with agricultural uses 

on ranch land (e.g., Royer 1992; 

Marrone 1992). Thus, the Dakota 

skipper had relatively more habitat, 

even if there were fewer known sites 

specifically in Minnesota. Furthermore, 

there is a tendency to assume that 

habitat protection (making a site a 

preserve) means the skippers in the 

preserve are secure; thus, if few are 

found on a given survey, the assumption 

is that this is due to the surveys being 

conducted at the wrong time, or due to 

fluctuations in abundance resulting 

from climatic variation. It is only 

through consistent long-term monitoring 

with the sites held constant (as in 

Swengel and Swengel 2013) that trend 

can be distinguished from those issues. 

Our Response: Because of the number 

of historical sites and the various ways 

that data were collected at those sites, 

we examined the range-wide data using 

detections and non-detections. We agree 

that there are few sites with consecutive 

years of data, and even fewer that have 

data over the long term. We have 

examined the data at individual sites 

where we had several consecutive years 

of data, and found that Poweshiek 

skipperling numbers have appeared to 

decline, along with the number of sites 

with positive detections (vs. nondetections) of the species. 

(129) Comment: A commenter stated 

that the sudden recent decline in 

Poweshiek skipperlings over the last 10 

years is likely because there are few new 

populations being discovered to replace 

the already undetectable, previously 

known populations. Furthermore, 

conservationists identified the best sites 

first; thus, more recently discovered 

populations were not as large and robust 

as the earlier discovered populations. 

Those more fragile populations would 

have less favorable prospects for longterm persistence. This also contributes 

to the sense that decline is now 

occurring everywhere. In addition, in 

some places, such as North Dakota, the 

dramatic population declines of the 

Poweshiek skipperling primarily 

occurred prior to 2000 (see Royer and 

Marrone 1992a, b; and Orwig 1994; 

1995; 1996; and 1997). 

Our Response: We acknowledge that 

there are documented declines in 

Poweshiek skipperling populations 

prior to 2000. However, in our 

comprehensive review, it appears that 

many sites with known populations of 

Poweshiek skipperlings have 

simultaneously declined to undetectable 

levels across much of the species’ range 

in the early 2000s. 

Factors Affecting the Species—General 

(130) Comment: A commenter stated 

that, throughout the proposed listing 

rule, the Service attributes perceived 

threats to the Dakota skipper as threats 

to the Poweshiek skipperling or vice 

versa. The Service must independently 

evaluate threats to each species and may 

not assume that a threat to one species 

is necessarily a threat to the other. 

Our Response: We have conducted 

the analysis of factors affecting the 

species separately for the two species. 

Since these two species have similar 

biology and are often found in the same 

locations, they face similar or identical 

threats at many locations. Therefore, 

when describing the factors, we discuss 

their effects to both species together 

when they are the same or similar. For 

example, if a remnant (untilled) native 

tallgrass prairie is being considered for 

a housing development, the resulting 

habitat conversion would affect both 

species by removing suitable habitat 

from the landscape. 

(131) Comment: A commenter stated 

that listing these species will impede 

the use of certain grassland management 

tools such as grazing, haying, burning, 

and chemical spraying that are 

necessary to meet the desired habitat for 

these butterflies. 

Our Response: The listing of these 

two butterflies will not necessarily 

impede the use of these grassland 

management tools. The Service 

recognizes that management, including 

grazing, haying, prescriptive fire or 

targeted herbicide treatments, may be 

needed to benefit the species and their 

habitats, as discussed in Factor A and 

Factor E of this final listing rule, below. 

The types, extent, duration, and 

intensity of various management 

regimes that would benefit the 

butterflies may depend on the specific 

past, present, or future threats at that 

location. The success of management 

regimes will need to be monitored and 

adjusted accordingly. 

(132) Comment: A commenter noted 

that suggestions of ‘‘light,’’ ‘‘limited’’ 

and ‘‘no’’ grazing and ‘‘late-season 

haying’’ are mentioned in the proposed 

rule to support rebuilding the butterfly 

populations. However, such practices 

have proven to have long-term 

implications that will actually do the 

opposite. For instance, limiting or 

eliminating grazing and haying is likely 

to promote invasion by exotic grasses, 

such as smooth brome grass and 

Kentucky bluegrass, which will compete 

with the very same native species that 

the butterflies require for habitat. The 

Service should encourage and 

incentivize grazing and haying 

approaches, such as rotational grazing, 

that would support both the economic 

viability of livestock operations and 

butterfly population growth. 

Our Response: Conservation of Dakota 

skipper and Poweshiek skipperling 

populations relies on careful 

implementation of management 

practices that conserve its habitat while 

minimizing adverse effects to 

reproduction and survival. Rotational 

late-season haying after the adult flight 

period, for example, can be beneficial to 

the species’ habitat. We have developed 

Dakota skipper conservation guidelines 

(http://www.fws.gov/midwest/

endangered/insects/dask/

DASKconservationguidelines.html), 

which describe those practices in more 

detail, and are developing similar 

guidelines for the Poweshiek 

skipperling. We discuss both the harm 

and the benefits that various 

management practices may have on 

prairie habitats in Factors A and E of 

this final listing rule (below). 

(133) Comment: A commenter stated 

that grassland easements are a broadbrush approach to conserve native 

prairies, but there is no targeted 

program or recovery plan specific to the 

Dakota skipper that would provide 

financial incentives and technical 

information for ranchers and farmers to 

manage habitat in a way that would 

expand the population of Dakota 

skippers. 

Our Response: Service programs, 

including Partners for Fish and Wildlife 

and State and tribal grant programs, are 

available to develop projects and 

partnerships to conserve these and other 

species. Following listing, the Service 

will develop a recovery plan for these 

two species. 

(134) Comment: A commenter stated 

that beaver dams can cause water level 

fluctuations in some Poweshiek 

skipperling areas in Michigan. The 

commenter asked whether these 

fluctuations, or the act of returning the 

water level to its normal level, harm 

Poweshiek skipperling larvae or habitat. 

Our Response: It is possible that 

higher than normal water levels, for an 

extended amount of time, may harm 

larvae. We discuss fluctuating water 

levels in Factor E of this final listing 

rule, below. 

Factor A 

(135) Comment: A commenter stated 

that current Dakota skipper population 

sites are already protected, and the 

imminent threat to the species is 

deemed to be on ‘‘remnant habitat.’’ 

Our Response: While some Dakota 

skipper sites are on land that is 

protected from some threats, such as 


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conversion of remnant prairies to other 

uses, the Dakota skipper populations at 

these sites are still exposed to other 

stressors, as we detailed in the 

Summary of the Factors Affecting the 

Species section of this final listing rule, 

below. 

(136) Comment: A commenter stated 

that the Dakota skipper and Poweshiek 

skipperling do not warrant listing 

because the Service improperly 

characterized oil and gas development 

as a threat to the Dakota skipper and 

Poweshiek skipperling, overstated the 

amount of oil and gas development 

occurring in the ranges of the Dakota 

skipper and Poweshiek skipperling, 

incorrectly assumed that the level of oil 

and gas development seen in western 

North Dakota will occur throughout the 

species’ ranges, and erred by concluding 

that impacts from oil development in 

western North Dakota to the two 

butterflies are similar to impacts from 

coal-bed natural gas in Wyoming on the 

greater sage-grouse. Accordingly, the 

Service should withdraw the listing and 

critical habitat rules. 

Our Response: The Act directs us to 

determine whether a species is an 

endangered species or a threatened 

species because of any factors affecting 

its continued existence. Listing actions 

may be warranted based on any of the 

five factors, singly or in combination. 

We completed a comprehensive 

assessment of the biological status of the 

Dakota skipper and Poweshiek 

skipperling, and all factors that might 

affect its existence. The effects from oil 

and gas activities are just one of the 

factors we considered. Our 

determinations that the Dakota skipper 

is a threatened species and the 

Poweshiek skipperling is an endangered 

species are based on numerous threats, 

acting individually and synergistically, 

that are leading to substantial 

population declines. 

Specifically with regard to our 

evaluation of impacts from oil and gas 

activities, much of this activity is 

currently occurring in areas of native 

prairie overlying the Bakken and Three 

Forks formations, to the west of known 

locations for both butterfly species. 

However, current Bakken oil and gas 

development is occurring in two 

counties that have records of Dakota 

skippers (McKenzie and McLean 

counties in North Dakota). In those 

areas, oil and gas development is a 

stressor to the populations that may be 

present. Because there are few locations 

where the butterflies may still be extant, 

significant stressors to these few 

populations can be threats to the species 

as a whole. Furthermore, although oil 

and gas development is unlikely to 

occur throughout the entire range of the 

two butterflies in the foreseeable future, 

there may be future development or 

increases in current activities associated 

with the shale-oil formations (such as 

the Bakken formation in North Dakota) 

that may affect butterfly populations in 

those areas. Finally, we used the Naugle 

et al. (2011) study and its impacts to 

sage grouse as a surrogate to estimate 

the impacts of similar energy 

development projects to the butterfly 

habitat. Because the Powder River Basin 

development varies from the 

development in the Bakken formation, 

we have corrected our estimations and 

analysis in this final listing rule (see 

Destruction and Conversion of Prairies 

to Nonagricultural Development, 

below). 

(137) Comment: A commenter noted 

that wind energy is not a threat to the 

species in North Dakota. The Service’s 

conclusion that wind energy 

development will expand into the 

ranges of the Dakota skipper and 

Poweshiek skipperling, and thus is a 

threat to the species, is based on 

outdated data and is poorly supported. 

The Service must justify its assumptions 

that wind energy will expand into 

Dakota skipper and Poweshiek 

skipperling range and consequently be a 

threat to the species. 

Our Response: We have evaluated the 

stressors to populations at sites where 

we had sufficient information to do so. 

Generally, we consider that wind 

development will have localized 

impacts in a few sites. We know of at 

least one site where a proposed wind 

development project poses a threat to 

the Dakota skipper and its habitat. 

Another wind farm is proposed within 

2 miles of areas we proposed as critical 

habitat, with expansion phases that 

could overlap that critical habitat. Both 

of these projects are in the draft 

Environmental Analysis stage of 

development. See Destruction and 

Conversion of Prairies to Agricultural 

Land, below, for a full discussion on 

impacts from wind energy development. 

(138) Comment: The proposed listing 

determination relies heavily on the 

work of McCabe and Royer for North 

Dakota, who have both published 

generalized statements about impacts of 

grazing on the Dakota skipper. These 

authors do not discuss the types of 

animals, season of use, intensity of 

grazing, or whether a grazing system is 

involved. 

Our Response: The Service used 

butterfly surveys and habitat reports 

written by Royer, McCabe, Spomer, and 

others to inform our determination on 

the status of the species in North 

Dakota. These authors also often 

reported stressors they observed at sites, 

such as invasive species encroachment 

or intensive grazing practices. We also 

used other reports and publications to 

inform the discussion regarding grazing 

effects on the butterflies, which 

included a discussion regarding types of 

animals, intensity of grazing, habitat 

type, proximity of nearby populations, 

associated herbicide use, and timing. In 

the conservation guidelines for the 

Dakota skipper (http://www.fws.gov/

midwest/endangered/insects/dask/

DASKconservationguidelines2013.html), 

we further discuss grazing in terms of 

intensity, duration, season of use, and 

type of habitat. 

(139) Comment: A commenter stated 

that invasive plant control needs to be 

done very carefully and in small-scale 

treatments to ensure any adverse effects 

on the Poweshiek skipperling, or the 

vegetative conditions they specifically 

require, are minimized, as invasive 

plant and brush control is not 

automatically beneficial to the butterfly. 

Specifically, at the Puchyan Prairie site, 

there is greater risk of unintended 

negative side effects of invasive plant 

control on Poweshiek skipperlings 

themselves, or the specific types and 

structures of vegetation they require, 

than risk of habitat deterioration in the 

next several years, if a more cautious 

approach is used. More time should be 

allowed to assess and describe the full 

extent of the kinds of microhabitats 

used by the Poweshiek skipperling, 

which likely differ among years due to 

climatic variation, and the extent of any 

change or deterioration in the vegetation 

in their core habitat areas. 

The commenter also stated that the 

Service is also correct that fire 

management, without careful planning, 

may have significant adverse effects on 

these skippers; however, the Service 

understates the risks of fire. A number 

of areas of good Dakota skipper and 

Poweshiek skipperling habitat have 

been converted by fire management over 

the last several decades from light 

agricultural land uses to areas lacking 

the features needed by the butterflies. 

These converted areas in Iowa, 

Minnesota, and westward have few 

recent records of either species. Fen 

wetland preserves in Michigan do have 

recent Poweshiek skipperling records, 

but some of these sites have new, not 

long-term, fire management. The 

Poweshiek skipperling has not fared 

well in the working landscape; thus, 

deliberate conservation effort is needed. 

Our Response: We agree that 

conservation of Poweshiek skipperling 

populations relies on careful 

implementation of management 

practices that conserve its habitat, while 


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minimizing adverse effects to 

reproduction and survival, including 

invasive species control at the few sites 

where the Poweshiek skipperling 

remains, such as Puchyan Prairie. As 

discussed in Factor A. The Present or 

Threatened Destruction, Modification, 

or Curtailment of Its Habitat or Range, 

below, encroaching invasive plants may 

replace or reduce the coverage of native 

forbs and grasses used by adults and 

larval butterflies and, therefore, need to 

be controlled. However, we further 

discuss that control methods (such as 

fire and herbicide spraying) may have 

their own unintended consequences, 

such as reduced native forbs and grasses 

and direct mortality of the butterflies, if 

not conducted carefully. Furthermore, 

various habitat types at these sites may 

respond differently to various types of 

control treatments. Therefore, when 

considering recovery planning for the 

species, it will be important to continue 

to individually assess sites to determine 

the need to control invasive species, 

exercise caution when implementing 

treatments, monitor the response to any 

treatments over the long-term, and 

refine or modify treatments as needed to 

get desired outcomes. Similarly, 

assessment and long-term monitoring of 

the species’ needs, such as microhabitat 

use, will help inform conservation 

efforts at specific locations. 

(140) Comment: One commenter 

recommended that land managers be 

advised as to the appropriateness of 

prescribed burns in Poweshiek 

skipperling habitat. 

Our Response: The Service contacted 

all of the landowners within proposed 

critical habitat designations as part of 

this rulemaking process. We have 

developed conservation guidelines for 

the Dakota skipper (online at http://

www.fws.gov/midwest/endangered/

insects/dask/

DASKconservationguidelines.html), and 

are developing similar guidelines for 

Poweshiek skipperling. Contact the 

Service’s Ecological Services Field 

Office in your State to discuss 

prescribed burn practices on land where 

one or both species may be present. 

(141) Comment: One commenter 

recommended that sites with Dakota 

skipper populations where fire 

management is not already occurring 

should remain fire-free, and that fire 

management should cease in core 

habitat for the Dakota skipper. Instead, 

cautious rotational haying or grazing 

regimes should be used to rehabilitate 

grassland vegetation to the shorter turf 

height that Dana (1991) recommends for 

the species. 

Our Response: We have developed 

conservation guidelines for the Dakota 

skipper (http://www.fws.gov/midwest/

endangered/insects/dask/

DASKconservationguidelines.html), and 

are developing similar guidelines for 

Poweshiek skipperling. The 

recommendations will be reviewed for 

possible incorporation as we continue to 

refine these guidelines. 

(142) Comment: A commenter noted 

that the proposed rule states that the 

negative effects of fire persist for 1 to 5 

years, citing Swengel (1996, pp. 73, 79, 

81) and Panzer (2002, pp. 1302–3). 

These papers, however, include a range 

of butterfly species found in prairies, 

not just localized prairie specialists like 

the Dakota skipper and Poweshiek 

skipperling. Panzer’s study contains no 

data on the Poweshiek skipperling or 

Dakota skipper. Swengel (1996) 

includes specific analysis of both 

species, but no explicit predictions are 

made. Swengel (1996, pp. 73, 79) 

describes that the negative effects of fire 

persist for specialists for 3 to 5 or more 

years. Swengel (1996) does not indicate 

an expectation of recovery 1–2 years 

post-burn for these species. Thus, 

Swengel’s analysis is better used to 

define when recovery has certainly not 

occurred (within years 0–3), but not 

when recovery actually has occurred. 

Our Response: We corrected our 

interpretation of the Swengel (1996) and 

the Panzer (2002) papers as discussed 

under Factor A. The Present or 

Threatened Destruction, Modification, 

or Curtailment of Its Habitat or Range, 

below, to better reflect the included data 

and information. We also changed our 

use of the word ‘‘recovery’’ in this 

context to the term ‘‘rebound,’’ which 

more accurately describes an upward 

trend, but does not imply a stable 

recovered trend in populations. 

(143) Comment: A commenter noted 

that Dana (1991, pp. 55–56) discusses 

concern about grass growth structure 

and height, namely that fire encourages 

taller grass growth, but that Dakota 

skippers prefer shorter grass. Therefore, 

effectively controlling weeds and brush 

does not necessarily mean that the 

management is creating suitable habitat 

for skippers. In the long run, fire does 

not produce a suitable vegetative 

structure for skippers. The long-term 

compounding indirect effect of fire on 

the vegetation (increasing grass height 

and thickness) may have a more lasting 

impact on the species and be more 

difficult to manage. 

Our Response: We will consider the 

longterm effect of fire on native 

vegetation growth and structure when 

developing and refining conservation 

guidelines for the Dakota skipper and 

Poweshiek skipperling. 

(144) Comment: The data used for 

North Dakota in the proposed listing 

rule relies heavily on the work of 

McCabe and Royer, who have both 

published generalized statements about 

grazing and its effects on the Dakota 

skipper. These authors do not discuss 

the types of animals, season of use, 

intensity of grazing or whether a grazing 

system is involved. 

Our Response: The Service relied on 

butterfly surveys and habitat reports 

written by Royer, McCabe, Spomer, and 

others to inform species and habitat data 

in North Dakota. These authors also 

often reported stressors they observed at 

sites, such as invasive species 

encroachment or intensive grazing 

practices. We used various other reports 

and publications to inform the 

discussion regarding grazing in Factor A 

of this final listing rule and included a 

discussion regarding types of animals, 

intensity of grazing, habitat type, 

proximity of nearby populations, 

associated herbicide use, and timing. In 

our conservation guidelines for Dakota 

skipper, we further discuss grazing in 

terms of intensity, duration, season of 

use, and type of habitat. 

(145) Comment: A commenter noted 

that low-intensity grazing is mentioned 

as a potential management tool to help 

maintain habitat and abate other threats 

to these two species. In some cases, 

high-intensity, short-duration grazing 

may have a role in providing the 

disturbance that prairies require to 

prevent them from being overrun by 

woody plants, and invasive species. 

Our Response: We have developed 

conservation guidelines for the Dakota 

skipper’s specific needs. These 

guidelines include some grazing 

recommendations; however, we are 

interested to learn more details about 

the effects of grazing practices 

implemented in various areas as we 

continue to refine our 

recommendations, and will take this 

information into consideration. 

(146) Comment: A commenter noted 

that data suggest Poweshiek skipperling 

populations at sites that were hayed 

prior to preservation did not recover to 

the same level following any subsequent 

fire. 

Our Response: We acknowledge that 

fire management may be detrimental to 

the Poweshiek skipperling, if not 

conducted properly. We are developing 

conservation guidelines for the 

Poweshiek skipperling that will address 

fire management and other actions, and 

are interested to learn more about the 

implications of fire practices as we 

continue to develop and refine our 

conservation recommendations. 


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(147) Comment: A commenter stated 

that the Service should provide data to 

support that fire management, even if 

applied to most or all of the patch 

occupied by the Dakota skipper or 

Poweshiek skipperling, has a low effect 

on the long-term persistence of these 

populations. The Service does not cite 

long-term studies of impacts from fire, 

but instead provides a list of 

assumptions, such as the following: (1) 

Fire happens in prairie (although the 

extent of that in a natural context is 

open to great debate; see literature 

review in Swengel and Swengel 2007, p. 

264); (2) these skippers live in prairie; 

(3) fire has various effects on prairie 

plants (although it should not be 

assumed that fire controls brush and 

weeds; see Swengel et al. 2011, p. 535); 

(4) those floristic effects are assumed to 

be beneficial to these skippers (although 

vigorous tall grass growth caused by fire 

may not be; see Dana 1991, pp. 5–56). 

Based on these assumptions, the Service 

concludes that fire should be fine for 

these skippers. The Service needs to 

provide direct positive evidence 

indicating that the skippers, especially 

the larvae, actually succeed in the long 

term following a fire. 

Our Response: We will consider all 

factors and data regarding the effects of 

fire on the species during recovery 

planning and implementation and in 

developing and refining the 

conservation guidelines for these two 

species. We acknowledge that there are 

no long-term (more than two decades) 

studies of fire management that 

provided data showing long-term 

persistence of the populations. We 

based our threats analysis and ranking 

of stressors as high, medium, and low 

based on the studies cited in our 

discussion of impacts from fire under 

the Summary of the Factors Affecting 

the Species section of this final rule, 

below. The possibility that we may have 

underestimated the stressors of fire 

management on the species further 

supports our determinations that fire 

can be a significant stressor to 

populations of Poweshiek skipperlings. 

(148) Comment: A commenter stated 

that there are problems with some 

reports that use McCabe’s 1981 

management recommendations, because 

McCabe’s paper reflects a point-in-time. 

Prairie ecology requires long-term 

observations and knowledge of how past 

and current management activities 

impact plant community dynamics. 

Further, prairie management 

conclusions based upon observations 

made in 1981 are no longer valid, due 

to changes in ecological drivers caused 

by broad-scale invasion of exotic coolseason grasses and forbs. 

Our Response: McCabe’s 1981 report 

is used as a reference to prairie 

conditions prior to much habitat 

degradation or exotic species invasions 

that are common in many locations 

today. We acknowledge that an 

understanding of prairie ecology 

requires long-term observations, as well 

as knowledge of how past and current 

management activities have impacted 

and continue to impact plant 

community dynamics. 

(149) Comment: One commenter 

agreed that annual haying on or after 

August 1 presents little or no stress to 

Dakota skippers. However, the 

commenter went on to point out that 

Swengel (1998b) found that Poweshiek 

skipperling abundance was strongly 

correlated with increasing number of 

years since the last management action, 

of any management type, including 

haying. Thus, annual haying of the 

entire habitat patch should be 

considered a high stressor for the 

Poweshiek skipperling. The Service is 

correct that alternate-year haying is 

better than annual haying, but it’s even 

better when the haying is done 

rotationally (half per year, instead of all 

every other year). Additionally, the 

moderate stressor category for haying is 

confusing. As it currently reads, a site 

could fall in the moderate category 

because you do not know the timing of 

the haying, but if you did know the 

timing, you would place it in the high 

category. 

Our Response: We developed the 

stressor categories for the purposes of 

the threats analysis to inform our listing 

determinations; these categories are not 

intended to be prescriptive conservation 

measures or guidelines. We 

acknowledge that there is some 

uncertainty in the ‘moderate’ stressor 

category for haying, but we wanted to 

fairly capture sites where we were 

unsure of the timing of haying activities, 

but that showed signs indicative of 

reduced nectar sources. It is true that 

these sites could be moved into the low 

or high category if we received more 

specifics on the timing of haying in 

those locations, and those details will be 

more important during the recovery 

planning stages for these species. 

Factor B 

(150) Comment: A commenter noted 

that recent publications report that 

nonlethal sampling of genetic material 

adds an immeasurable or minor effect 

on survival or reproductive success of 

butterflies compared to handled 

individuals that were not also 

genetically sampled (Marschalek et al. 

2013; Crawford et al. 2013). However, 

there is abundant literature on how 

handling has adverse effects on 

butterflies, documented for a wide range 

of species (e.g., Benson and Emmel 

1973; Singer and Wedlake 1981; 

Lederhouse 1982; Morton 1984). It is 

possible that some types of nonlethal 

sampling do not significantly increase 

the harm to the butterfly from capture 

and handling, but the handling for such 

sampling still causes harm compared to 

the butterfly not being handled. Thus, 

the benefits of such sampling should be 

weighed against the harm caused to 

individuals. 

Our Response: As stated under Factor 

B of this final rule, handling stress 

during scientific study may affect 

individuals of both species. Adverse 

effects on butterflies have been 

documented for a wide range of species 

(e.g., Benson and Emmel 1973, p. 329; 

Singer and Wedlake 1981, pp. 215–216; 

Lederhouse 1982, pp. 381–382; Morton 

1984, pp. 56–57; Mallet et al. 1987, pp. 

380–383). The Service will consider 

stress and other impacts to the 

butterflies from handling when issuing 

scientific permits for genetic sampling 

and other sampling efforts. 

(151) Comment: A commenter noted 

that reliably effective captive 

propagation has not been demonstrated 

for either of these species. However, the 

Service should consider and assess the 

effect on wild populations of either 

species before attempting to develop 

captive propagation. 

Our Response: The Service will 

consider incidental take for otherwise 

legal activities in our permitting (e.g., 

section 10 recovery permits) process. 

Factor D 

(152) Comment: A commenter stated 

that as of August 2013, the Minnesota 

Department of Natural Resources listed 

both the Dakota skipper and the 

Poweshiek skipperling as endangered. 

The Dakota skipper is also an 

‘‘endangered’’ species under Iowa law. 

Our Response: We have updated the 

State-level protections for Dakota 

skipper and Poweshiek skipperling in 

Factor D of this final listing rule. 

Factor E 

(153) Comment: A commenter stated 

that herbicides applied in skipper 

habitat can negatively affect nectar 

resources for the species. However, 

herbicide use can have benefits if 

carefully targeted to treating brush and 

weeds, so long as bare ground does not 

subsequently result from the treatment, 

as bare ground greatly facilitates 

recruitment of new weed and brush 

growth. 

Our Response: We acknowledge that 

carefully targeted herbicide treatments 


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may result in the beneficial control of 

nonnative or invasive plants and brush, 

and have clarified our statements in 

Factor E of this final listing rule, below. 

(154) Comment: A commenter noted 

that results of a preliminary analysis of 

the genetic diversity of the Poweshiek 

skipperling show limited levels of 

genetic diversity in the Wisconsin, 

Michigan, and Manitoba populations. 

Demographic factors are of greater 

concern, specifically, small population 

sizes and numbers of populations are 

more likely to lead to extinction than 

loss of genetic diversity. The 

widespread and intensive survey effort 

showing continual extirpation of 

populations and reduced population 

sizes supports the listing of Poweshiek 

skipperling as endangered. 

Our Response: We have incorporated 

information from the preliminary results 

of Saarinen (2013, pers. comm.) under 

Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence, in the discussion on Habitat 

Fragmentation and Population Isolation, 

below, and look forward to receiving 

final results from this research to inform 

future conservation efforts for this 

species. 

(155) Comment: A commenter stated 

that weather and climate events, such as 

the persistent drought in the Midwest, 

and their effects on the Dakota skipper 

and Poweshiek skipperling require 

further study. Funding and staff are 

needed to accomplish these efforts. 

Our Response: In this rule, we used 

the best available information on 

climate and climate change, however we 

agree that more study of weather and 

climate events will help us with 

recovery planning and implementation 

for these two species, and will consider 

new information when developing the 

recovery plan. 

(156) Comment: A commenter stated 

that, in its assessment of impacts to the 

butterflies from climate change, the 

Service ignores model uncertainty that 

the Intergovernmental Panel on Climate 

Change (IPCC) acknowledges. 

Our Response: We appreciate your 

comment and understand that there are 

uncertainties in the climate modeling. 

We consider climate change to be a 

potential threat to the species, while 

acknowledging uncertainty of how 

changes may specifically impact these 

species or their habitats. 

(157) Comment: A commenter stated 

that, while it is possible that unknown 

threats to the species exist, it is 

inappropriate to focus too much effort 

on the search for unknown stressors. 

This distracts from addressing the 

challenges of dealing with the stressors 

that have been known for decades 

(isolated populations in fragmented 

habitats that are under pressure from 

habitat degradation and land 

management practices). 

Our Response: We acknowledge that 

multiple stressors are acting on 

populations of both species, and have 

been so for many years. In our review, 

however, it appears that many sites with 

known populations of the Poweshiek 

skipperling appear to have 

simultaneously declined to undetectable 

levels. A similar, but perhaps delayed, 

decline is being observed in Dakota 

skipper populations. We did not want to 

rule out the possibility that this decline 

may be due to some unknown cause. 

However, we will focus on all potential 

factors affecting the species in recovery 

planning and implementation, not 

simply on any single factor. 

Determinations 

(158) Comment: A commenter stated 

that the Dakota skipper and Poweshiek 

skipperling are both threatened by loss 

of native prairie vegetation to 

agriculture, development, altered fire 

patterns, and groundwater depletion. 

The Dakota skipper and Poweshiek 

skipperling are also threatened by 

pesticides, drought, and climate change. 

In light of the population declines and 

ongoing threats, both butterflies should 

be protected as endangered rather than 

as threatened. 

Our Response: The Dakota skipper is 

experiencing population declines and 

facing multiple threats. A few 

populations in the United States are 

doing relatively well, however, and are 

in habitats that have low or nonimmediate threats. Furthermore, Canada 

has an estimated 15 populations on 

lands that are being utilized in a manner 

conducive to the conservation of Dakota 

skipper, and the threats at those sites are 

not imminent. Based on our review of 

the best available scientific and 

commercial information, we conclude 

that the Dakota skipper is likely to 

become in danger of extinction in the 

foreseeable future throughout all of its 

range and, therefore, meets the 

definition of a threatened species. For a 

detailed discussion, see the 

Determination section of this final rule, 

below. 

(159) Comment: A commenter stated 

that the Service should list the Dakota 

skipper as endangered, as it is ‘‘in 

danger of extinction throughout all or a 

significant portion of its range.’’ The 

species is present at 91 sites, at least 83 

‘‘are subject to one or more threats that 

have a moderate to high impact on those 

populations.’’ The Service does not 

explain why 8 sites that are presumably 

secure outweigh 83 sites that are 

experiencing moderate to high threat 

levels, especially since ‘‘Dakota skipper 

. . . habitat is highly fragmented and 

because the species are subject to local 

extinction . . . and approximately 84 

percent of Dakota skipper sites with 

present or unknown status are 

effectively isolated.’’ 

Our Response: We agree that the 

Dakota skipper is imperiled, which is 

why we determined that the species 

warrants listing under the Act. 

However, we believe that the Dakota 

skipper is not in immediate danger of 

going extinct at this point in time. 

Instead, we believe that, if trends 

continue as they currently are, the 

species is likely to get to that point in 

the foreseeable future. Because there are 

stable populations of the Dakota skipper 

that do not appear to be currently 

suffering from high-magnitude threats, 

and the declining trends are happening 

at a slower pace, we determined that 

threatened species status is appropriate 

for the Dakota skipper (see 

Determination, below, for a full 

discussion). 

(160) Comment: A commenter stated 

that the Service determines that the 

Dakota skipper is a threatened species 

because ‘‘Canada has a fair number of 

populations that are being managed in 

a manner conducive to the conservation 

of Dakota skipper, and the threats at 

those sites are not imminent.’’ A ‘‘fair 

number’’ is not a biologically 

meaningful measure. The Service needs 

to explain this contention in a 

measurable manner. 

Our Response: We are aware of 14 

sites in Canada where the species is 

considered to be present and one site 

where the occupancy is unknown. 

Those sites are managed by late-season 

haying (after August 1) that is 

conducted at least every other year, and 

there is no indication that native plant 

diversity is declining due to timing or 

frequency of mowing. 

(161) Comment: A commenter stated 

that the Canadian populations are 

functionally isolated from each other 

and from U.S. populations. The distance 

between all these metapopulations 

makes interaction or recolonization 

unlikely, as Dakota skippers may be 

incapable of moving greater than 1 km 

(0.6 mi) between patches of prairie 

habitat separated by structurally similar 

habitats. The Service did not conduct an 

adequate analysis of ‘‘significant portion 

of range,’’ to determine if the three 

metapopulations (U.S., Manitoba, and 

Saskatchewan) should each be 

considered ‘‘significant,’’ and if one is 

‘‘in danger of extinction,’’ then the 

species as a whole should be listed as 

endangered. The Service must 


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separately analyze threats to each 

isolated metapopulation because 

population isolation and accompanying 

loss of genetic diversity are 

acknowledged to have significant 

impacts on the species. 

Our Response: Under the Act and our 

implementing regulations, a species 

may warrant listing if it is endangered 

or threatened throughout all or a 

significant portion of its range. Because 

we have determined that the Dakota 

skipper is a threatened species 

throughout all of its range, no portion of 

its range can be ‘‘significant’’ for 

purposes of the definitions of 

‘‘endangered species’’ and ‘‘threatened 

species.’’ See the Final Policy on 

Interpretation of the Phrase ‘‘Significant 

Portion of Its Range’’ in the Endangered 

Species Act’s Definitions of 

‘‘Endangered Species’’ and ‘‘Threatened 

Species’’ (79 FR 37577, July 1, 2014). 

(162) Comment: A commenter stated 

that the Service has an obligation to 

make available the studies that form the 

basis of its action. The Service failed to 

provide any materials other than its own 

draft species assessment and textual 

descriptions of proposed critical habit 

for either the proposed listing or critical 

habitat designation in the 

regulations.gov docket or on its Web 

sites. The Service did provide a 

bibliography; however, many references 

cited were unpublished reports or 

internal documents. 

Our Response: One element of the 

transparency and open government 

directive encourages executive 

departments and agencies to make 

information about operations and 

decisions readily available to the public. 

Supporting documentation used to 

prepare the proposed and final rules is 

available for public inspection, by 

appointment, during normal business 

hours, at the U.S. Fish and Wildlife 

Service, Twin Cities Ecological Services 

Field Office, 4101 American Boulevard 

East, Bloomington, Minnesota 55425. 

4(d) Rule 

(163) Comment: One commenter said 

that the 4(d) rule proposed for the 

Dakota skipper should be extended to 

remove prohibitions for take incidental 

to lawfully conducted oil and gas 

operations and that this would not 

undermine the goal of promoting the 

healthy growth of these populations 

throughout their entire range. The 

commenter indicated that the activities 

that were addressed by the proposed 

4(d) rule—a variety of routine livestock 

ranching activities and mowing of 

recreational trails—were far more 

widespread in the region and contribute 

more directly to the threats listed in the 

proposed rule than were oil and gas 

related activities. 

Our Response: Although livestock 

ranching activities and mowing of 

recreational trails may be more 

widespread throughout the species 

range, livestock grazing also can be a 

key factor in the conservation of Dakota 

skipper habitat, by helping to ensure 

that the species’ habitats are not 

subjected to activities that result in their 

permanent destruction. That is, lands 

are likely to remain unplowed as long 

as the landowner chooses to continue to 

use them for grazing. In addition, 

grazing may also be implemented in a 

manner that provides significant 

benefits to the species. In these ways oil 

and gas production and grazing are 

fundamentally different with respect to 

Dakota skipper conservation. 

Regardless, the Service recognizes that a 

variety of interests, including oil and 

gas activities, may hold the potential to 

contribute to Dakota skipper 

conservation. 

(164) Comment: One commenter 

stated that the 4(d) rule would provide 

an important incentive to continue latesummer haying where that practice is 

currently being implemented. 

Our Response: We agree that the 4(d) 

rule will provide this incentive, as 

intended. Late-summer haying is 

currently the primary management on 

numerous sites inhabited by Dakota 

skipper that are important for the 

species’ conservation. 

(165) Comment: One commenter 

requested that we also exempt take 

caused by ‘‘construction with minimal 

disturbance, such as that for 

transmission lines, that occurs after July 

15th’’ in the 4(d) rule. The same 

commenter requested that the Service 

‘‘give consideration to exempting 

transmission line maintenance activities 

and existing right-of-way maintenance 

in the same way that section line 

maintenance is exempted in the 

proposed 4(d) rule.’’ 

Our Response: It is unclear which 

populations could be affected by these 

activities, what the effects might be, and 

how the effects might be minimized. 

Therefore, we have not included these 

activities in the 4(d) rule. 

(166) Comment: One commenter 

stated that ‘‘the proposed 4(d) rule will 

undermine, not advance, conservation 

of the species’’ and that the 4(d) rule 

was not needed to prevent habitat 

destruction because it would already be 

illegal under section 9 of the Act and 

uninhabited areas at risk for conversion 

would be protected by designating them 

as critical habitat. 

Our Response: It is true that take of 

Dakota skippers that results from 

destruction of its habitat would be 

prohibited under section 9 of the Act, 

but there are other reasons to 

promulgate the 4(d) rule. As we stated 

in the proposed rule, the 4(d) rule will 

facilitate cooperation with private 

landowners that will be needed to 

recover the species. About 47 percent of 

the sites where the Dakota skipper has 

been recorded in the United States and 

that may still harbor the species are on 

private land. Almost all of these sites 

are working lands managed with grazing 

or haying. Conservation of the Dakota 

skipper on these sites, and in general, 

will require the Service and other 

conservation agencies and groups to 

develop and maintain cooperative 

partnerships with private landowners. 

Without that cooperation, we are 

unlikely to realize the substantial 

improvements in habitat conditions and 

public-private partnerships necessary to 

conserve the species. 

(167) Comment: A commenter stated 

that the proposed 4(d) rule does not 

provide details as to how the Service 

intends to ensure that infrastructure, 

such as corrals, loading chutes, and 

other livestock working facilities, are 

carefully sited so that impacts to the 

species are minimized. 

Our Response: These types of 

facilities are unlikely to have significant 

impacts to Dakota skipper populations, 

except where the species has been 

reduced to only very small areas. In 

grazed lands that are typically inhabited 

by Dakota skipper, these facilities affect 

only small proportions of the available 

habitat. Therefore, we do not think that 

the small degree of impact posed by 

placement of livestock working facilities 

would merit site-specific approval and 

review by the Service. Instead, by 

foregoing any requirement for 

landowners to seek Service approval for 

siting these facilities, we are likely to 

further facilitate continued development 

of positive working relationships that 

will be essential for recovering the 

species. In addition, we can work with 

landowners on voluntary methods to 

minimize any impacts that might result 

from installation of facilities associated 

with grazing. 

(168) Comment: One commenter 

stated that the protections afforded the 

Dakota skipper through the 4(d) rule are 

not sufficient to reverse the trend 

toward extinction because they do not 

ensure that the grazing practices 

exempted under the rule will benefit the 

Dakota skipper. 

Our Response: It may not be 

practicable to expect broad 

implementation of specific mandated 

grazing practices on private land to 

conserve the Dakota skipper without the 


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willingness of the landowner to 

implement those practices. 

Conservation of Dakota skippers on 

grazed lands will require several steps 

that include the development of sitespecific grazing recommendations, 

monitoring the effects of the recommend 

practices on the Dakota skipper and its 

habitat, and science-based adaptive 

management. Each step will require 

access to private and other non-Federal 

lands by persons with expertise in 

identifying and describing the Dakota 

skipper and its key habitat components 

and, in at least some cases, by grazing 

experts and conservation partners. 

Landowners and land managers may be 

less likely to grant access for these 

activities if we broadly mandate specific 

grazing practices. Furthermore, although 

the incidental take permitting process 

would also provide an avenue by which 

to work with private landowners and is 

often the best available option for some 

species, there is no clear avenue that is 

immediately available by which to 

engage the large and geographically 

widespread group of landowners in 

such a process for Dakota skippers. A 

permitting process that would involve 

more than a few landowners is likely to 

take years and would have significant 

potential to become contentious and 

unwieldy. 

(169) Comment: One commenter 

suggested that, instead of listing 

counties in which take caused by 

grazing would not be exempted under 

the 4(d) rule, the Service should base 

this on habitat. 

Our Response: We decided that it is 

more appropriate to exempt take of 

Dakota skippers caused by grazing on all 

non-Federal lands in the United States, 

regardless of geographic area, and have 

made this change in the final 4(d) rule. 

We recommend, however, that lands 

where native prairie is currently 

maintained by haying continue to be 

hayed, and that any change to grazing 

on these lands only be done with the 

prior input from experts in Dakota 

skippers and range conservation. We 

suggest contacting the Service’s 

Ecological Services Office in your State 

for more information. 

(170) Comment: A commenter asked 

what areas can be treated for weeds or 

pests and still be exempted by the 4(d) 

rule. 

Our Response: The 4(d) rule does not 

address control of animal pests; 

therefore, it does not exempt take that 

may result from treatments that are 

applied to control animal pests. The 

4(d) rule also does not exempt take of 

Dakota skippers that would result from 

the broadcast application of 

herbicides—that is, application of 

herbicides evenly across all or a portion 

of an area. Take of Dakota skippers that 

is caused by applications of herbicide 

that do not meet this definition of 

broadcast spraying would be exempted 

by the 4(d) rule. 

Take of Dakota skippers is unlikely if 

they do not inhabit an area where 

broadcast application of herbicides is 

proposed. If the presence of Dakota 

skippers is suspected in an area where 

broadcast application of herbicides is 

proposed, we recommend that the 

Service be contacted to determine 

whether the action may be likely to 

cause take of the species, and if 

reasonable measures may be adopted 

that would avoid take. 

Summary of Changes From the 

Proposed Rule 

Based on our review of the public 

comments, comments from other 

Federal and State agencies, peer review 

comments, issues addressed at the 

public hearing, and any new relevant 

information that may have become 

available since the publication of the 

proposal, we reevaluated our proposed 

rule and made changes as appropriate. 

During the comment periods, the 

Service received additional survey 

information, minor clarifications, and 

additional information on the species 

biology. New survey information has 

changed the occupancy status at several 

sites, for example a site that we 

considered to be ‘‘unknown’’ in the 

proposed rule may now be considered 

‘‘extirpated’’ due to three sequential 

years of negative survey data. 

Consequently, some sites were dropped 

from our analysis of factors affecting the 

species because we no longer consider 

the species to be present or possibly 

present (unknown) at a particular 

location. In addition, we included new 

information into our analysis of the 

factors affecting the species. Neither the 

new information nor the updated 

occupancy at some sites has 

significantly changed our analyses such 

that it changed our determinations of 

status under the Act for either species. 

The 4(d) rule now exempts take of 

Dakota skippers caused by grazing on all 

non-federal lands in the United States; 

the proposed 4(d) rule did not apply to 

certain lands in Minnesota and North 

Dakota. The final 4(d) rule no longer 

exclude some counties from the part of 

the rule that exempts take caused by 

grazing. Other minor changes to the 4(d) 

rule include: Clarifying broadcast versus 

spot-spraying of herbicides; defining 

‘‘recreational trail’’; and, that take of 

Dakota skipper caused by haying in 

transportation rights-of-ways and 

corridors after July 15 is exempt under 

the 4(d) rule, as long as it is associated 

with livestock ranching activities. The 

4(d) rule exempts take of Dakota 

skippers caused by mowing recreational 

trails, a term that is defined in the rule, 

even when it is not associated with 

livestock grazing. 

Summary of the Factors Affecting the 

Species 

Factor A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Habitat quality is a powerful 

determinant of extinction probability in 

butterflies such as the Dakota skipper 

and Poweshiek skipperling (Thomas et 

al. 2001, p. 1795). Among butterfly 

species in the United Kingdom, for 

example, equilibrium density of 

butterflies at sites with optimum habitat 

are from 25 to more than 200 times 

greater than those for occupied sites 

with suboptimal, yet suitable, habitat 

(Thomas 1984, cited in Thomas et al. 

2001, p. 1794). Consistently good 

habitat quality is especially important 

for Dakota skipper and Poweshiek 

skipperling isolated populations, which 

would not be naturally recolonized if 

they were extirpated. Protection or 

restoration of habitat quality at these 

isolated sites is critical to the survival 

of both species, although stochastic 

events still pose some risk, especially 

for smaller populations and at small 

sites. 

The Poweshiek skipperling and 

Dakota skipper depend on a diversity of 

native plants endemic to tallgrass 

prairies and, for the Poweshiek 

skipperling in Michigan, prairie fens. 

When nonnative or woody plant species 

become dominant, Poweshiek 

skipperlings and Dakota skippers 

decline due to insufficient sources of 

larval food and nectar for adults. For 

example, at Wike Waterfowl Production 

Area in Roberts County, South Dakota, 

the extirpation of Poweshiek skipperling 

is attributed to the deterioration of 

native vegetation, in particular, the loss 

of nectar sources for adult butterflies 

due to invasive species encroachment 

(Skadsen 2009, p. 9). 

Destruction of native tallgrass and 

mixed-grass prairie began in 1830 

(Samson and Knopf 1994, pp. 418–419). 

Extant populations of Dakota skipper 

and Poweshiek skipperling are 

restricted to native-prairie remnants and 

prairie fens; native prairies have been 

reduced by 85 to 99.9 percent of their 

former area throughout the historical 

range of both species (Samson and 

Knopf 1994, pp. 418–419). Degradation 

and destruction of habitat occurs in 

many ways, including but not limited 


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to: Conversion of native prairie to 

cropland or development; ecological 

succession to woody vegetation; 

encroachment of invasive species; past 

and present fire, haying, or grazing 

management that degraded or destroyed 

the species’ habitats; flooding; and 

groundwater depletion, alteration, and 

contamination, which are discussed in 

further detail below. 

We evaluated the level of impact to 

the population at each site of several 

habitat-related stressors at 163 Dakota 

skipper sites where the occupancy 

status of the site is considered to be 

present or unknown, as defined in the 

Background section of this final rule 

(Table 3, above). These 163 sites are 

found across the current range of the 

species in Minnesota, North Dakota, and 

South Dakota. Eight sites with an 

unknown or present occupancy were 

not evaluated. To determine the levels 

of impact to the population at each site, 

we used the best available and most 

recent information for each site, 

including reports, discussions with site 

managers, information from natural 

heritage databases, etc. (Service 2012, 

unpubl. data; Service 2014, unpubl. 

geodatabase). We only evaluated a 

stressor to the population at any one site 

if we had sufficient information to 

determine if the level of impact was 

high, medium, or low as defined for 

each stressor below. Similarly, the level 

of impact to the population was 

evaluated at 60 Poweshiek skipperling 

sites with present or unknown status 

(Table 4). Although we did not evaluate 

Factor A stressors at all 87 Poweshiek 

skipperling sites with present or 

unknown occupancy, the 60 sites that 

were evaluated are representative of all 

the present or unknown Poweshiek 

skipperling sites in terms of geography 

(range of the species, i.e., sites in Iowa, 

Michigan, Minnesota, North Dakota, 

South Dakota, and Wisconsin were 

evaluated), ownership, and 

management. Many sites for both 

species (58 sites for Dakota skipper and 

26 sites for Poweshiek skipperling) 

experience at least two habitat-related 

stressors at a medium or high level of 

impact (Tables 3 and 4). 

TABLE 3—NUMBER OF DAKOTA SKIPPER SITES WITH EACH LEVEL OF IMPACT AND THE TOTAL NUMBER OF SITES THAT

WERE RATED FOR EACH TYPE OF STRESSOR. A TOTAL OF 163 DAKOTA SKIPPER SITES WITH EITHER PRESENT OR

UNKNOWN STATUS WERE EXAMINED; ONLY SITES WITH SUFFICIENT DATA FOR A PARTICULAR STRESSOR WERE

RATED AS HIGH, MEDIUM, OR LOW

[Service 2012 Unpubl. data; Service 2014, unpubl. geodatabase] 

Stressor High level 

of impact 

Medium level 

of impact 

Low level 

of impact 

Total number 

of rated sites 

Destruction & Conversion (Agricultural & Nonagricultural Development) ....... 3 83 58 144 

Wind Development .......................................................................................... 1 0 8 9 

Flooding ........................................................................................................... 2 6 6 14 

Invasive Species .............................................................................................. 12 33 20 65 

Fire ................................................................................................................... 10 4 6 20 

Grazing ............................................................................................................ 9 29 14 52 

Haying & Mowing ............................................................................................. 1 11 29 41 

Lack of Management ....................................................................................... 9 5 3 17 

Size/Isolation .................................................................................................... 50 50 63 163 

Herbicide and/or Pesticide Use ....................................................................... 5 2 8 15 

TABLE 4—NUMBER OF POWESHIEK SKIPPERLING SITES WITH EACH LEVEL OF IMPACT AND THE TOTAL NUMBER OF SITES

THAT WERE RATED FOR EACH TYPE OF STRESSOR. A TOTAL OF 60 POWESHIEK SKIPPERLING SITES WITH EITHER

PRESENT OR UNKNOWN STATUS WERE EXAMINED; ONLY SITES WITH SUFFICIENT DATA FOR A PARTICULAR

STRESSOR WERE RATED AS HIGH, MEDIUM, OR LOW

[Service 2012 unpubl.; Service 2014, unpubl. data] 

Stressor High level 

of impact 

Medium level 

of impact 

Low level 

of impact 

Total number 

of rated sites 

Destruction & Conversion (Agricultural & Nonagricultural Development) ....... 2 11 28 41 

Wind Development .......................................................................................... 0 0 5 5 

Flooding/Hydrology .......................................................................................... 2 3 14 19 

Invasive Species .............................................................................................. 6 29 11 46 

Fire ................................................................................................................... 4 2 10 16 

Grazing ............................................................................................................ 4 10 2 16 

Haying & Mowing ............................................................................................. 0 3 3 6 

Lack of Management ....................................................................................... 4 6 2 12 

Size/Isolation .................................................................................................... 21 22 11 54 

Herbicide and/or Pesticide Use ....................................................................... 3 1 5 9 

Destruction and Conversion of Prairies 

Destruction and Conversion of Prairies 

to Agricultural Land 

Conversion of prairie for agriculture 

may have been the most influential 

factor in the decline of the Poweshiek 

skipperling and Dakota skipper since 

Euro-American settlement, but the 

impacts of such conversion on extant 

populations is not well known. By 1994, 

tallgrass prairie had declined by 99.9 

percent in Illinois, Iowa, Indiana, North 

Dakota, Wisconsin, and Manitoba; and 

by 99.6 percent in Minnesota; and 85 

percent in South Dakota (Samson and 

Knof 1994, p. 419). Samson and Knof 

(1994, p. 419) did not provide a figure 

for the decline of tallgrass prairie in 

Saskatchewan, but mention an 81.3 

percent decline in mixed grasses from 

historical levels. By 1994, mixed-grass 

prairie had declined from historical 

levels by 99.9 percent in Manitoba and 


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71.9 percent in North Dakota (Samson 

and Knof 1994, p. 419). Destruction of 

tallgrass and mixed-grass prairie began 

in 1830, but significant documentation 

of the ecosystem’s butterfly fauna did 

not begin until about 1960. Therefore, 

most of the decline of the Dakota 

skipper and Poweshiek skipperling 

probably went unrecorded. 

Since about 1980, observers have 

documented the extinction of several 

populations of the Dakota skipper and 

Poweshiek skipperling due to habitat 

conversion to agricultural use in the 

United States and Canada. For example, 

four Dakota skipper sites in North 

Dakota were converted to irrigated 

potato fields, and one in South Dakota 

was converted for crop production 

(Royer and Marrone 1992a, p. 17). The 

Fannystelle site in Manitoba, where the 

Dakota skipper was last recorded in 

1991, was subsequently converted for 

row-crop agriculture (Webster 2003, p. 

7). In North Dakota, further conversion 

is a stressor to Dakota skippers in the 

important Towner-Karlsruhe complex 

(Royer and Royer 1998, p. 22; Lenz 

1999, p. 13), where the flat topography 

and high water table facilitate 

conversion to irrigated crop production. 

Populations of Dakota skipper in 

Manitoba typically occupy flat terrain 

that may be vulnerable to conversion to 

cropland, although soil conditions may 

be unsuitable for row crops at some of 

these sites (Webster 2003, p. 10). 

Similarly, conversion of native prairie to 

cropland continues to be a threat to 

Poweshiek skipperling habitat 

throughout its range (Royer and 

Marrone 1992b, p. 17). 

The Dakota skipper, and until 

recently, the Poweshiek skipperling, 

have largely persisted in areas that are 

relatively unsuitable for row crop 

agriculture because of their steep terrain 

(e.g., in the Prairie Coteau of South 

Dakota) or where soils are too wet or 

rocky for row-crop agriculture (McCabe 

1981, pp. 189–190, Webster 2003, p. 10). 

Densely spaced, large glacial rocks, for 

example, may have deterred cultivation 

at the Chippewa Prairie in Minnesota 

and ‘‘spared Chippewa Prairie in 

Minnesota from the plow’’ (Dana 2012, 

pers. comm.). In areas where Poweshiek 

skipperling and Dakota skipper habitat 

persists but is adjacent to agriculture, 

added nutrients from agricultural runoff 

affects groundwater and additional 

nutrients in the system contribute to the 

dominance of invasive plants (Fiedler 

and Landis 2012, p. 51: Michigan 

Natural Features Inventory 2012, p. 4). 

In summary, conversion for 

agriculture on lands suitable for such 

purposes is a current, ongoing stressor 

of high level of impact to the Poweshiek 

skipperling and Dakota skipper 

populations in areas where such lands 

still remain. Advances in technology 

may also increase the potential of 

conversions in areas that are currently 

unsuitable for agriculture. 

We rated the level of impact to the 

populations of the stressor posed by 

habitat destruction or conversion for 

both agriculture and nonagricultural 

purposes (except for conversion for 

wind energy development, which was 

analyzed separately) at 144 Dakota 

skipper and 41 Poweshiek skipperling 

sites with present or unknown status 

(see Tables 3 and 4) where we had 

sufficient information to evaluate the 

stressor. In our evaluation of this 

stressor, we combined agricultural and 

nonagricultural impacts—our analyses 

are discussed below (see Destruction 

and Conversion of Prairies due to 

Nonagricultural Development). 

Destruction and Conversion of Prairies 

to Nonagricultural Development 

Conversion of prairie for 

nonagricultural land uses, such as 

energy development, gravel mining, 

transportation, and housing are stressors 

to both Poweshiek skipperling and 

Dakota skipper populations. For 

example, a site where the Dakota 

skipper and Poweshiek skipperling were 

recorded in 1997 (Skadsen 1997, pp. 

15–16, B–1) in the Bitter Lake area of 

Day County, South Dakota, is now a 

gravel pit, and the species’ habitat no 

longer exists there (Skadsen 2003, pp. 

47–48). 

Almost all prairie remnants with 

Poweshiek skipperling and Dakota 

skipper populations are associated with 

gravelly glacial till soils (Service 2014, 

unpubl. geodatabase); therefore, gravel 

mining is a potential stressor to 

populations at a large number of sites. 

Gravel mining is a stressor to Poweshiek 

skipperling and Dakota skipper 

populations at several sites in 

Minnesota (Dana 1997, p. 15). For 

example, gravel mining is a stressor in 

at least three of the five sites that 

comprise the Felton Prairie complex 

(Cochrane and Delphey 2002, pp. 16– 

17); however, the Clay County 

Stewardship Plan (Felton Prairie 

Stewardship Committee 2002) may have 

reduced the likelihood of the gravel 

mining stressor to populations at this 

complex. On at least seven sites in 

Minnesota, Dakota skippers inhabit 

northern dry prairie plant communities, 

which are generally impacted by gravel 

mining due to the predominance of 

gravel soils (Minnesota DNR 2006, p. 

221). Gravel mining is a stressor to 

populations of Dakota skipper in central 

Manitoba (Rigney 2013a, p. 28). Gravel 

mines are considered a stressor with a 

high level of impact to populations of 

both species because, where it occurs, 

the habitat is completely destroyed. 

Potash (salt that contains potassium) 

mining is a stressor to Dakota skipper 

populations in some Saskatchewan sites 

(Westwood 2013, pers. comm.), 

although the exact number of sites that 

are being considered for potash mining 

is unknown and were not included in 

our stressor evaluation. 

Energy development (oil, gas, and 

wind) and associated roads and 

facilities result in the loss or 

fragmentation of suitable prairie habitat 

(Reuber 2011, pers. comm.). Major areas 

of recent oil and gas development, such 

as that occurring in the Bakken 

formation, overlaps with parts of the 

Dakota skipper’s range in North Dakota. 

North Dakota, for example, is now one 

of the top two oil-producing states in 

the United States, and new development 

is occurring rapidly (MacPherson 2012, 

p. 1; North Dakota Petroleum Council 

2012, p. 1). The number of drilling 

permits in North Dakota nearly doubled 

between 2007 and 2008, from 494 

permits issued in 2007 to 946 in 2008 

(North Dakota Petroleum Council 2009, 

p. 2). Permits dropped to 627 in 2009 

(North Dakota Petroleum Council 2010, 

p. 2), but increased dramatically to 

1,676 in 2010 (Ogden 2011, p. 1). While 

much of the oil activity is currently 

occurring in areas of native prairie 

overlaying the Bakken and Three Forks 

formations to the west of known 

locations for both species, mineral 

exploration has occurred in all but one 

county in North Dakota (North Dakota 

Petroleum Council 2012, p. 1). 

McKenzie County falls in the center of 

this development and McHenry County 

is also within these formations (Mueller 

2013, pers. comm.). The oil 

development on the Bakken formation 

in North Dakota, for example, may be a 

future stressor to Dakota skipper 

populations in McKenzie County (Royer 

and Royer 2012b, p. 16). Oil production 

is anticipated to continue to expand at 

record levels (MacPherson 2012, p. 1; 

MacPherson 2010, entire). 

Native-prairie habitat would be 

destroyed in the footprint of an oil and 

gas well pad, but the pads are relatively 

small. However, each oil and gas well 

pad requires new road construction, and 

evidence suggests that Poweshiek 

skipperlings may avoid crossing roads 

(Westwood et al. 2012, p. 18). Energy 

development can double the density of 

roads on range lands (e.g., Naugle et al. 

2011, pp. 493–494), increase pipelines, 

and increase the number of gravel pits 

to accommodate the increased road 

construction (Mueller 2013, pers. 


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comm.). Development for coal-bed 

natural gas (as described in Naugle 

2011), for example, in areas with 

ranching, tillage agriculture, and oil and 

gas development, 70 percent of the 

developed land was within 100 m (109 

yards (yd)), and 85 percent of the 

developed land was within 200 m (218 

yd), of a human structure (Naugle et al. 

2011, p. 493). Researchers estimated 

that, in those areas, every square km 

(0.39 square miles) of land may be both 

bounded by a road and bisected by a 

power line (Naugle et al. 2011, p. 493). 

These coal-bed natural gas 

developments can be densely located 

(e.g., 8 wells per 640 acres) and are 

drilled vertically, whereas shale-oil 

wells in the Bakken formation are 

drilled horizontally and ‘‘relatively far 

apart’’ (Conoco Phillips 2013, in litt.). 

The habitat fragmentation associated 

with oil and gas development may 

amplify other stressors to both species, 

such as the effects of population 

isolation and the impacts of stochastic 

events. 

Energy development has additional 

undesirable and potentially significant 

cumulative impacts on wildlife. 

Catastrophic events, such as oil and 

brine spills, could cause direct mortality 

of Dakota skipper or Poweshiek 

skipperling larvae that are in shelters at 

or below the soil surface. Such spills 

may also cause the loss of larval host 

and nectar plants in the spill path. 

Additional plants may be lost during 

spill response, particularly if the 

response involves burning. The 

likelihood, however, of spills occurring 

on the small fraction of land that 

remains native tallgrass prairie in North 

Dakota (less than one percent according 

to Samsom and Knoff 1994, p. 419) is 

low. 

Wind energy turbines and associated 

infrastructure (e.g., maintenance roads) 

are likely stressors to Dakota skipper 

and Poweshiek skipperling populations, 

particularly on private land in South 

Dakota (Skadsen 2002, p. 39; Skadsen 

2003, p. 47; Skadsen 2012d, pers. 

comm.). Similar to oil and gas 

development, wind development would 

destroy native-prairie habitat in the 

footprint of the structure, add access 

roads and other infrastructure that may 

further fragment prairies, and could be 

catalysts for the spread of invasive 

species. Further, it is unknown if the 

noise and flicker effects associated with 

wind turbines may impact Dakota 

skipper or Poweshiek skipperling 

populations beyond direct impacts from 

the turbines and/or infrastructure. Other 

wildlife species, such as birds, have 

shown significant avoidance of 

grasslands where wind development has 

occurred (Pruett et al. 2009, p. 1256; 

Shaffer et al. 2012,unpaginated). Wind 

development was assessed at nine 

Dakota skipper sites and six Poweshiek 

skipperling sites where we had 

sufficient information. The level of 

threat was considered to be low at most 

sites because, although the site may be 

in an area with the potential for wind 

development, there are no specific plans 

or proposals to develop wind power on 

the site. 

Wind development is considered a 

stressor of high level of impact to 

populations at sites where development 

is proposed and there are no actions or 

plans to mitigate impacts to the species. 

For example, a wind facility was 

recently proposed at a Dakota skipper 

site in South Dakota (Skadsen 2012d, 

pers. comm.), which poses a high-level 

threat for the species at that site because 

there are no plans to mitigate impacts of 

habitat destruction. Although wind 

power development currently poses a 

high level of impact to the population 

at only one site, the extent of this 

stressor will likely increase in the 

future, due to the high demand for wind 

energy and the number of Dakota 

skipper and Poweshiek skipperling sites 

that are conducive to wind development 

(e.g., Skadsen 2003, pp. 47–48). 

Furthermore, power transmission lines 

may be developed in order to 

accommodate the added power of wind 

farms, for instance, a new power line is 

currently being planned in the Prairie 

Coteau in South Dakota for that purpose 

(Mueller 2013, pers. comm.). 

Housing construction has likely 

contributed to the loss of at least two 

Poweshiek skipperling populations in 

Michigan, and the largest extant 

population in Michigan is located in an 

area under intense development 

pressure (Michigan Natural Features 

Inventory 2011, unpubl. data). 

Residential wells and drainage disrupt 

prairie fen hydrology by reducing water 

levels and, thus, facilitating rapid 

growth of woody vegetation. In 

addition, nutrients added to the 

groundwater from leaking septic tanks 

contribute to the dominance of invasive 

plants, such as narrow-leaved cattail 

(Typha angustifolia) and red canary 

grass (Phalaris arundinacea) (Michigan 

Natural Features Inventory 2012, p. 4). 

Road construction impacts Poweshiek 

skipperling and Dakota skipper habitat 

because it increases the demand for 

gravel, and impacts also result from 

routine maintenance (e.g., broadcast 

herbicide applications, early mowing, 

and cleaning out ditches), 

improvements (e.g., widening roads or 

converting two-lane highways to fourlane highways), or new construction. 

Poweshiek skipperling habitat was 

destroyed or degraded on at least two 

private properties in Roberts County, 

South Dakota, for example, in 

association with the widening of U.S. 

Highway 12 (Skadsen 2003, p. 47). 

Roadside prairie remnants can help 

support populations of both species and 

serve as dispersal corridors between 

larger remnants; therefore, loss of these 

areas to road expansion or construction 

further reduces and fragments 

remaining habitat. In Michigan, at least 

one Poweshiek skipperling site and its 

habitat has been negatively affected by 

recreational ‘mud bogging’, which 

destroys vegetation and creates 

conditions conducive to invasive 

species (Hicks 2014, pers. comm.). 

In summary, nonagricultural 

development, such as gravel mining, 

activities associated with energy 

development, or housing and road 

development, poses a current stressor of 

moderate to high impact to populations 

on those lands that are not protected 

from destruction or conversion through 

a conservation easement or fee title 

ownership by a conservation agency. 

This type of development may become 

more widespread as such practices 

increase in the future. 

As discussed above in Destruction 

and Conversion of Prairies to 

Agricultural Land, we rated the level of 

impact to the populations of the stressor 

posed by habitat destruction or 

conversion for both agriculture and 

nonagricultural purposes combined 

(except for conversion for wind energy 

development, which was analyzed 

separately) at 144 Dakota skipper sites 

with present or unknown status (see 

Table 3) where we had sufficient 

information to evaluate the stressor. The 

level of impact of each stressor to the 

population at each site is high at three 

of those sites, due to ongoing 

destruction of the native prairie, or there 

was a high likelihood of conversion 

because it is located close to other 

converted areas and the land is 

conducive for agriculture. The level of 

threat is high at 3 sites, moderate at 83 

sites, and 58 sites are protected from 

destruction or conversion through a 

conservation easement or fee title 

ownership by a conservation agency 

(Table 3). This stressor occurs across the 

range of the Dakota skipper; the stressor 

has a medium to high level of impact to 

Dakota skipper populations in 

Minnesota, North Dakota, South Dakota, 

Manitoba, and Saskatchewan. The level 

of impact was considered to be low if 

the site is protected from destruction or 

conversion by fee title ownership by a 

governmental conservation agency, 

nongovernmental conservation 


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organization (e.g., The Nature 

Conservancy), or educational institution 

(e.g., South Dakota State University). 

Similarly, 41 Poweshiek skipperling 

sites with present or unknown status 

were assessed that had sufficient 

information: The level of threat was 

high at 2 sites and moderate at 11 sites, 

and 28 sites are protected from 

destruction or conversion through a 

conservation easement or fee title 

ownership by a conservation agency 

(Table 4). At least 6 of the 12 sites where 

the Poweshiek skipperling is considered 

to still be present have a medium or 

high risk of conversion. This stressor 

occurs across most of the Poweshiek 

skipperling range; the stressor has a 

medium to high level of impact to 

Poweshiek skipperling populations in 

Iowa, Michigan, Minnesota, and South 

Dakota; the level of impact is low for the 

species at the Manitoba location. 

Fluctuating Water Levels 

Flooding is a stressor to Poweshiek 

skipperlings and Dakota skippers at 

sites where too much of the species’ 

habitat is flooded or where patches are 

flooded too frequently. Poweshiek 

skipperlings and Dakota skippers must 

either survive flooding events in 

numbers sufficient to rebuild 

populations after the flood or recolonize 

the area from nearby areas that had not 

flooded. In addition, the return interval 

of floods must be infrequent enough to 

allow for recovery of the populations 

between floods. Changes in hydrology 

resulting from wetland draining and 

development may permanently alter the 

plant community and, therefore, pose a 

threat to Poweshiek skipperling and 

Dakota skipper due to loss of larval food 

and nectar sources. 

The Dakota skipper and Poweshiek 

skipperling are presumed extirpated 

from several sites due to flooding or 

draining. For example, one Dakota 

skipper site was lost to flooding due to 

rising water levels at Bitter Lake, South 

Dakota (Skadsen 1997, p. 15). At 

Whalen Lake Fen in Michigan, dredging 

and channelization disrupted the 

hydrology of the site and the fen has 

since been invaded by glossy buckthorn 

and narrow leaf cattail; Poweshiek 

skipperlings are presumed to be 

extirpated from the site (Michigan 

Natural Features Inventory 2011, 

unpubl. data). The loss of a large area 

of habitat at two sites in Manitoba, 

which were previously suitable for 

Dakota skipper, was caused by 

prolonged inundation of water that 

likely caused larval mortality and 

mortality of suitable nectar and larval 

food plants (Rigney 2013a, pp. 28, 153). 

In addition, flood protection activities 

and associated alteration of the 

landscape (e.g., road work that causes 

changes to overland drainage) is a 

stressor to the species at some sites in 

Manitoba (Rigney 2013a, p. 28). 

Fluctuating water levels are a current 

stressor to populations across both 

species’ ranges. Loss of habitat or direct 

mortality due to fluctuating water 

levels, such as permanent flooding or 

wetland draining, is a current stressor to 

populations in at least 14 Dakota 

skipper sites with present or unknown 

status and 19 Poweshiek skipperling 

sites with present or unknown status. 

For example, one of the three sites with 

present or unknown status of Poweshiek 

skipperling in Wisconsin, Puchyan 

Prairie, is subject to flooding—the entire 

prairie portion of the site was 

submerged in 1993 (Hoffman 2011, pers. 

comm.; Wisconsin DNR 2012, in litt). 

The number of Poweshiek skipperling 

observed at that site is consistently low. 

Flooding is a likely factor that has 

contributed to the low numbers 

observed in at least part of this site 

(Borkin 2012c, pers. comm.). 

Conversely, groundwater disruption 

and draining is a stressor at all 9 of the 

Michigan prairie fen Poweshiek 

skipperling sites where the species is 

present and high at one site with 

unknown occupancy. Interrupted 

groundwater flow-through fens can 

reduce water levels and facilitate woody 

vegetation establishment and growth 

(Michigan Natural Features Inventory 

2012, p. 4). Agricultural and residential 

drains and wells can lower the 

groundwater table, thereby reducing the 

supply of calcareous seepage, which is 

an essential underlying component of 

prairie fen hydrology (Michigan Natural 

Features Inventory 2012, p. 4). 

Furthermore, nutrient additions 

associated with drain fields can 

contribute to invasive species 

encroachment. For instance, if 

groundwater flow to prairie wetlands is 

severed, fen habitats may convert from 

native grasses and flowering forbs to 

habitats dominated by invasive species 

or woody vegetation (Fiedler and Landis 

2012, p. 51, Michigan Natural Features 

Inventory 2012, p. 4). The site with the 

highest number of Poweshiek 

skipperlings in Michigan, for instance, 

is partially bordered by residential areas 

and is under intense development 

pressure (Michigan Natural Features 

Inventory2011, unpubl. data). At least 8 

of the 11 fen sites with present or 

unknown status are at least partially 

unprotected from development, and at 

least 7 of those are closely bordered by 

roads, agriculture, or residential 

developments (Michigan Natural 

Features Inventory 2011, unpubl. data; 

Service 2014, unpubl. geodatabase). The 

status of Poweshiek skipperling is 

unknown at one fen site where the 

hydrology was likely disrupted by roads 

and extensive residential development 

in close proximity to the fen (Michigan 

Natural Features Inventory 2011, 

unpubl. data). 

The level of impact to populations 

due to flooding was assessed at 12 

Dakota skipper sites with present or 

unknown status that had sufficient 

information to evaluate the stressor 

(Table 3); this evaluation only included 

sites in North and South Dakota. 

Flooding is a stressor of moderate-level 

impact to populations at 6 of the sites, 

where there is evidence of recent or 

pending decrease in the quality or 

extent of suitable habitat at the site due 

to a change in wetland vegetation, 

wetland hydrology, or flooding—all of 

these sites occur in North Dakota 

(Service 2012 unpubl. data; Service 

2014, unpubl. data). Similarly, we 

assessed 19 Poweshiek skipperling sites 

with present or unknown occupancy for 

the level of impact to populations due 

to water fluctuations (e.g., flooding or 

draining) where we had sufficient 

information to evaluate the stressor 

(Table 4). Water fluctuations is a 

stressor with moderate impact to the 

populations at 3 Poweshiek skipperling 

sites (including a site in Wisconsin— 

one of the 12 Poweshiek skipperling 

sites with a present status), and changes 

to hydrology is a stressor of moderateto high-level impact to populations at 

all 11 Michigan sites (including 9 of 12 

Poweshiek skipperling sites that have a 

present status) and 1 site in North 

Dakota (Service 2012 unpubl. data; 

Service 2014, unpubl. geodatabase). 

In summary, fluctuating water levels 

is a current and ongoing stressor of 

moderate level of impact to populations 

where the habitat may be temporarily 

lost due to intermittent flooding and is 

a stressor of high severity where a 

change in hydrology may completely 

degrade the habitat quality of a site, 

particularly prairie fens. 

Invasive Species and Secondary 

Succession 

Poweshiek skipperlings and Dakota 

skippers typically occur at sites 

embedded in agricultural or developed 

landscapes, which make them more 

susceptible to nonnative or woody plant 

invasion. Nonnative species including 

leafy spurge, Kentucky bluegrass, 

alfalfa, glossy buckthorn, smooth brome, 

purple loosestrife (Lythrum salicaria), 

Canada thistle (Cirsium arvense), reed 

canary grass, and others, have invaded 

Poweshiek skipperling and Dakota 

skipper habitat throughout their ranges 


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(Orwig 1997, pp. 4, 8; Michigan Natural 

Features Inventory 2011, unpubl. data; 

Skadsen 2002, p. 52; Royer and Royer 

2012b, pp. 15–16, 22–23). Kentucky 

bluegrass and leafy spurge (and the 

persistent efforts for chemical control of 

leafy spurge) have been cited as one of 

the major stressors to native-prairie 

habitat at several public and privately 

owned Dakota skipper sites in North 

Dakota (Royer and Royer 2012b, pp. 15– 

16, 22–23; Royer 2012, pers. comm.; 

Royer 2013, pers. comm.). Once these 

plants invade a site, they replace or 

reduce the coverage of native forbs and 

grasses used by adults and larvae of 

both butterflies. Leafy spurge displaces 

native plant species, and its invasion is 

facilitated by actions that remove native 

plant cover and expose mineral soil 

(Belcher and Wilson 1989, p. 172). The 

seasonal senescence patterns (timing of 

growth) of grass species as they relate to 

the larval period of Dakota skippers 

determine which grass species are 

suitable larval host plants. Exotic coolseason grasses, such as Kentucky 

bluegrass and smooth brome, are 

available when Dakota skipper and 

Poweshiek skipperling larvae begin 

feeding; however, the morphology and 

growth habit of these grasses are likely 

major determinants of their 

unsuitability to support Dakota skippers 

(Dana 1991, pp. 46–47). Thus, a 

prevalence of these grasses reduces food 

availability for the larvae. 

The stressor from nonnative invasive 

herbaceous species is compounded by 

the encroachment of woody species into 

native-prairie habitat. Glossy buckthorn 

and gray dogwood encroachment, for 

example, is a major stressor to 

Poweshiek skipperling populations at 

the Brandt Road Fen in Michigan, 

which supports the second largest 

population of Poweshiek skipperlings in 

the State (Michigan Natural Features 

Inventory 2011, unpubl. data). Invasion 

of tallgrass prairie and prairie fens by 

woody vegetation such as glossy 

buckthorn reduces light availability, 

total plant cover, and the coverage of 

grasses and sedges (Fiedler and Landis 

2012, pp. 44, 50–51). This in turn 

reduces the availability of both nectar 

and larval host plants for Poweshiek 

skipperlings and Dakota skippers. If 

groundwater flow to prairie wetlands is 

disrupted (e.g., by development) or 

intercepted (e.g., digging a pond in 

adjacent uplands or installing wells for 

irrigation or drinking water), it can 

quickly convert to shrubs or other 

invasive species (Fiedler and Landis 

2012, p. 51; Michigan Natural Features 

Inventory 2012, p. 4). For example, 

roads and residential development 

likely disrupted the hydrology of a 

prairie fen where the Poweshiek 

skipperling was last observed in 2007 

and where 2008 and 2009 surveys for 

Poweshiek skipperlings were negative 

(Michigan Natural Features Inventory 

2011, unpubl. data). Furthermore, on 

some sites, land managers intentionally 

facilitated succession of native-prairie 

communities to woody vegetation or 

trees, such as Ponderosa pine (Pinus 

ponderosa) or spruce (e.g., Dana 1997, 

p. 5). This converts prairie to shrubland, 

forest, or semi-forested habitat types and 

facilitates invasion of adjacent native 

prairie by exotic, cool-season grasses, 

such as smooth brome. Moreover, the 

trees and shrubs provide perches for 

birds that may prey on the butterflies 

(Royer and Marrone 1992b, p. 15; 1992a, 

p. 25). 

We rated the level of impact to 

populations of invasive species at 65 

Dakota skipper sites and 46 Poweshiek 

skipperling sites that had sufficient 

information to evaluate the stressor 

(Table 3 and Table 4; Service 2012 

unpubl. data; Service 2014, unpubl. 

data). This stressor is considered to have 

a low level of impact to the populations 

if there was either no information to 

indicate a stressor or management was 

ongoing to control invasive species 

using methods that are unlikely to cause 

adverse effects to Dakota skippers or 

Poweshiek skipperlings (e.g., spotspraying or hand-pulling). Sites were 

assigned a moderate level of impact to 

populations if invasive species are 

typically a primary driver of 

management actions and make it 

difficult for managers to specifically 

tailor management to conserve Dakota 

skipper or Poweshiek skipperling 

habitat. The site was assigned a high 

level of impact to populations if one or 

more nonnative invasive plant species 

are abundant or increasing and 

management activities are not being 

implemented to control their expansion; 

or if necessary management actions 

cannot be implemented without 

themselves causing an additional 

stressor to the Dakota skipper or 

Poweshiek skipperling populations at 

the site. 

Invasive species are a current and 

ongoing stressor with high levels of 

impact to Dakota skipper and 

Poweshiek skipperling populations on 

sites where land management is 

conducive to their invasion or 

expansion or where they have become 

so pervasive that even favorable 

management may not be quickly 

effective. Succession is a current and 

ongoing stressor of moderate-level 

impact to populations at sites where 

management is insufficient. The stressor 

of invasive species to populations on 

small and isolated sites (e.g., Big Stone 

NWR) is a current and ongoing stressor 

of high level of impact to populations, 

because Dakota skipper and Poweshiek 

skipperling populations have little 

resilience to the resulting habitat 

degradation and to the often aggressive 

management needed to control the 

invasive plants. Loss of habitat or 

degradation of the native plant 

community due to encroachment of 

invasive species or woody vegetation is 

considered a high level of impact to 

populations at 12 of the 65 assessed 

Dakota skipper sites, a moderate level of 

impact to populations at 33 sites, and 

low impact to populations at 20 sites. 

Sites with high and moderate level of 

impact occur throughout the species 

range in Minnesota, and North and 

South Dakota (Service 2012 unpubl. 

data; Service 2014, unpubl. data). 

Similarly, invasive species are a stressor 

of high level of impact to populations at 

6 of the 46 evaluated Poweshiek 

skipperling sites, moderate level of 

impact to populations at 29 sites, and 

low level of impact to populations at 11 

sites—sites with high and moderate 

levels of impact are throughout the 

range of the species in Iowa, Minnesota, 

Michigan, North Dakota, South Dakota, 

Wisconsin, and Manitoba and include at 

least 9 of the 12 sites where the species 

is still present (Service 2014, unpubl. 

data). 

Fire 

Dakota skipper and Poweshiek 

skipperling populations existed 

historically in a vast ecosystem 

maintained in part by fire. Due to the 

great extent of tallgrass prairie in the 

past, fire and other intense disturbances 

(e.g., locally intensive bison grazing) 

likely affected only a small proportion 

of the habitat each year, allowing for 

recolonization from unaffected areas 

during the subsequent flight period 

(Swengel 1998, p. 83). Fire can improve 

Poweshiek skipperling (Cuthrell 2009, 

pers. comm.) and Dakota skipper habitat 

(e.g., by helping to control woody 

vegetation encroachment), but it may 

also kill most or all of the individuals 

in the burned units and alter entire 

remnant prairie patches, if not properly 

managed (e.g., depends on the timing, 

intensity, etc.). Accidental wildfires also 

may burn entire prairie tracts (Dana 

1997, p. 15) and may hamper plans to 

carefully manage Dakota skipper and 

Poweshiek skipperling habitat. A 

human-set wildfire in late fall 2009 and 

another extensive fire in 2011, for 

example, burned considerable amounts 

of good prairie habitat in The Nature 

Conservancy of Canada’s Tall Grass 


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Prairie Preserve in Manitoba (Hamel et 

al. 2013, p. 1; Westwood 2010, pers. 

comm.), which is the only location in 

Canada where Poweshiek skipperlings 

are present; Dakota skippers are 

extirpated from the site. The fires at The 

Nature Conservancy of Canada’s Tall 

Grass Prairie Preserve may have killed 

overwintering larvae, and the 

population of Poweshiek skipperling in 

Canada ‘‘may have been greatly reduced 

as a result of these fires’’ (Hamel et al. 

2013, p. 1). 

Intentional fires, without careful 

planning, may also have significant 

adverse effects on populations of Dakota 

skippers and Poweshiek skipperlings, 

especially after repeated events (McCabe 

1981, pp. 190–191; Dana 1991, pp. 41– 

45, 54–55; Swengel 1998, p. 83; Orwig 

and Schlicht 1999, pp. 6, 8). In 

systematic surveys of Minnesota 

tallgrass prairies, for example, Dakota 

skippers were less abundant on sites 

that had been burned, compared with 

otherwise similar hayed sites (Swengel 

1998, p. 80; Swengel and Swengel 1999, 

pp. 278–279). Similarly, Schlicht 

(1997b, p. 5) counted fewer Dakota 

skippers per hour in burned than on 

grazed sites in Minnesota. Orwig and 

Schlicht (1999, p. 8) speculated that 

inappropriate use of prescribed burning 

eliminated Dakota skippers from the last 

known occupied site in Iowa, a 65-ha 

(160-ac) preserve. The effects of fire on 

prairie butterfly populations are 

difficult to ascertain (Dana 2008, p. 18), 

but the apparent hypersensitivity of 

Poweshiek skipperlings and Dakota 

skippers indicates that it is a stressor to 

both species in habitats burned too 

frequently or too broadly. The 

Poweshiek skipperling and Dakota 

skipper are not known to disperse 

widely (Swengel 1996, p. 81; Burke et 

al. 2011, p. 2279); therefore, in order to 

reap the benefits of fire to habitat 

quality, Poweshiek skipperlings and 

Dakota skippers must either survive in 

numbers sufficient to rebuild 

populations after the fire or recolonize 

the area from a nearby unburned area. 

In addition, the return interval of fires 

needs to be infrequent enough to allow 

for recovery of the populations between 

burns. Therefore, fire is a stressor to 

Poweshiek skipperlings and Dakota 

skippers at any site where too little of 

the species’ habitat is left unburned or 

where patches are burned too 

frequently. 

Panzer (2002, p. 1306) identified four 

life-history traits of duff-dwelling 

insects (such as the Dakota skipper and 

Poweshiek skipperling) that were good 

predictors of a negative response to fire: 

(1) Remnant dependence (occurring as 

small, isolated populations); (2) upland 

inhabitance (dry uplands burn more 

thoroughly than wetter habitats); (3) 

nonvagility (low recolonization rate); 

and (4) univoltine (slower recovery rates 

for species with only one generation per 

year). Species exhibiting all four traits 

should be considered ‘‘hypersensitive’’ 

to fire (Panzer 2002, p. 1306). While not 

specifically included in his study, the 

Poweshiek skipperling and Dakota 

skipper meet all of Panzer’s criteria for 

hypersensitivity (Panzer 2002, p. 1306) 

and have additional life-history traits 

that further suggest hypersensitivity to 

fire. Panzer (2002) observed mean 

declines of 67 percent among firenegative species, although actual 

mortality was likely higher due to some 

immigration into experimental areas 

after the burn. When all or large 

portions of prairie remnants are burned, 

many or all prairie butterflies may be 

eliminated at once. Complete 

extirpation of a population, however, 

may not occur after a single burn event 

(Panzer 2002, p. 1306), and the extent of 

effects would vary depending on time of 

year and fuel load. 

Poweshiek skipperlings lay their eggs 

near the tips of leaf blades, and they 

overwinter as larvae on the host plants 

(Borkin 2000, p. 2), where they are 

exposed to fires during their larval 

stages. Poweshiek skipperlings have 

also been documented laying eggs on 

the entire length of grass leaf blades and 

on low-growing deciduous foliage 

(Dupont 2013, p. 133). If larvae are on 

prairie dropseed or little bluestem, 

which occur in dry prairie, rather than 

spike-rush or sedges, which typically 

occur in wet prairie, then the larvae are 

even more vulnerable to fire (Selby 

2005, p. 36). Unlike Dakota skippers, 

Poweshiek skipperlings do not burrow 

into the soil surface (McAlpine 1972, 

pp. 88–92; Borkin 1995, p. 9), which 

makes them more vulnerable to fire (and 

likely more vulnerable to chemicals 

such as herbicides and pesticides) 

throughout their larval stages. Species 

whose larvae spend more time above 

ground, such as Poweshiek skipperlings, 

are likely more vulnerable to fire than 

species that form underground shelters. 

As the spring progresses, however, the 

vulnerability of Dakota skippers to fire 

increases as larvae shift from buried 

shelters to horizontal shelters at the soil 

surface (Dana 1991, p. 16). 

Studies of all life-stages may be 

necessary to fully evaluate these 

species’ response to fire. Early spring 

burns may be less likely to harm Dakota 

skipper populations than late spring 

burns, due to larval phenology and 

differences in subsurface soil 

temperatures during the fire; however, 

studies have not conclusively linked the 

relationship of mortality risk to the 

timing of spring burns. Experiments to 

evaluate the effects of early spring 

versus late spring fires and of different 

fuel levels on Dakota skipper mortality 

found that, despite higher ambient 

temperatures during the early spring 

burn, temperatures at the average depth 

of buried Dakota skipper shelters (Dana 

1991, p. 11) were 10 °C (50 °F) higher 

during the late-spring burn (Dana 1991, 

p. 41). Fuel load was positively related 

to subsurface soil temperature (Dana 

1991, pp. 41–43). Fuel loads that were 

clearly associated with lethal subsoil 

temperatures, however, were more 

typical of mesic tallgrass prairie, which 

had about twice the fuel loads of the 

dry-mesic habitats inhabited by Dakota 

skippers on the site (Dana 1991, pp. 41, 

54). Although Dana’s study was 

inconclusive in quantifying the risk of 

mortality in relation to the timing of 

spring burns, he was able to conclude 

that a late-spring burn in ‘‘moderate’’ 

fuels (430–440 g/m2) would have a 

devastating effect on Dakota skipper 

populations, and that early spring 

burning would afford some amelioration 

(Dana 1991, p. 55). 

Rotational burning may benefit prairie 

butterflies by increasing nectar plant 

density and by positively affecting soil 

temperature and near-surface humidity 

levels due to reductions in litter (Dana 

1991, pp. 53–55; Murphy et al. 2005, p. 

208; Dana 2008, p. 20). Purple 

coneflower and little bluestem, for 

example, occurred more frequently on 

burned areas than on unburned areas in 

mixed-grass prairie at Lostwood 

National Wildlife Refuge in 

northwestern North Dakota (Murphy et 

al. 2005, pp. 208–209). An increase in 

purple coneflower, an important nectar 

source for Dakota skippers and 

Poweshiek skipperlings, may last for 1– 

2 years after early spring fires, and 

females may preferentially oviposit near 

concentrations of this nectar source 

(Dana 2008, p. 20). 

Although fire tends to increase native 

plant diversity in prairies (Murphy et al. 

2005, pp. 208–209), several years may 

be necessary for Dakota skipper and 

Poweshiek skipperling populations to 

recover after a burn. Few studies have 

documented recovery times for prairie 

butterflies after a burn, and even fewer 

have measured the relationships 

between species abundance in tallgrass 

prairies and time since burn. One such 

study, however, found lower relative 

abundances of Dakota skippers and 

Poweshiek skipperlings in burned units 

than in otherwise similar hayed units 

even 4 years after burns (Swengel 1996, 

p. 83). Poweshiek skipperling had the 

most negative initial response to fire 


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among six species of prairie-obligate 

butterfly species (Swengel 1996, p. 83). 

Numbers were still lower than expected 

1 year post-fire, exceeded expectations 

after 2 years, and declined slightly after 

3 years (Swengel 1996, p. 83). In 

habitats that had not been burned for 4 

or more years, Poweshiek skipperling 

abundance was about as low as in 

habitats sampled less than 1 year after 

being burned (Swengel 1996, p. 83). The 

2012 spring burn that comprised 

approximately 25–30 percent of the 

breeding habitat at Scuppernong SNA 

may have contributed to the apparent 

absence of the species in 2013—the 

relatively small population that was also 

affected by the 2012 summer drought 

and the cold wet spring of 2013 (Borkin 

2014, pers. comm.) 

Poweshiek skipperling numbers 

decline in burned areas for at least 1– 

2 years after the burn, and may take 

several years to rebound, but may 

decline again if management does not 

maintain the habitat (Skadsen 2001, p. 

37; Webster 2003, p. 12). In general, 

rebound times of 1–5 years postburn 

have been predicted (Panzer 2002, pp. 

1302–1303); however, Vogel et. al (2010, 

p. 671) found that habitat-specialist 

butterfly abundance rebound time was 

approximately 50 months after 

prescribed fires. Swengel (1996, pp. 73, 

78–79) describes that the negative 

effects of fire persist for prairie 

specialists for 3 to 5 plus years, and 

these species were collectively the most 

abundant after 5 or more years since the 

last fire. In Manitoba, Poweshiek 

skipperling populations were most 

numerous in sites burned 5–8 years 

previously—the species was absent in 

sites that were burned the previous year, 

in small numbers in areas that were 

burned 2–4 years prior, and absent from 

areas that were burned 10 or more years 

previous to the survey (Dupont 2013, 

pp. 4, 86–87). Recent survey results in 

some areas, most notably, Iowa and 

Minnesota, indicate that other factors 

are acting independently (Dana 2008, p. 

18) or in concert with fire to forestall 

post-fire rebound. 

We assessed the stressor posed by fire 

at 20 Dakota skipper sites with present 

or unknown status and 16 Poweshiek 

skipperling sites with present or 

unknown status where we had sufficient 

information to evaluate the stressor 

(Tables 3 and 4; Service 2012, unpubl. 

data; Service 2014, unpubl. data). We 

considered fire a stressor of high level 

of impact to populations at 10 of the 20 

evaluated Dakota skipper sites and 4 of 

the 16 Poweshiek skipperling sites. Sites 

that face a high level of impact to 

populations were primarily those with a 

high proportion of Dakota skipper or 

Poweshiek skipperling habitat that may 

be burned in a single year or where all 

of the species’ habitat is burned with no 

likely source of immigrants to sustain 

the population. This type of fire 

management is a documented cause of 

extirpation (Selby 2000, p. 19). Sites 

with a moderate level of impact to 

populations from fire management were 

those where the habitat is divided into 

at least three burn units and no unit is 

burned more frequently than once every 

3 years; or, habitat is divided into two 

or more burn units, each unit is burned 

no more frequently than once every 3 

years, but the entirety of the species’ 

habitat is never burned in the same year 

and the species is present at another site 

that is less than 1 km (1.6 mi) away. 

Fire is considered to be a stressor of 

moderate severity at 4 of the 20 

evaluated Dakota skipper sites and 2 of 

the 16 Poweshiek skipperling sites. Fire 

presents a low level of impact to 

populations at sites where the species’ 

habitat is divided into at least four burn 

units and no unit is burned more 

frequently than once every 4 years; or, 

the species’ habitat is divided into three 

or more burn units, at least three units 

are burned no more frequently than 

once every 4 years, and the site contains 

more than 140 ha (346 ac) of native 

prairie or where the site is separated 

from another occupied site by less than 

1 km (1.6 mi). Fire is considered to be 

a stressor with a low level of impact to 

populations at 6 of the 20 evaluated 

Dakota skipper sites and 10 of the 16 

Poweshiek skipperling sites. 

In summary, fire may be an important 

management tool for these butterflies, if 

carried out appropriately. However, 

where managers burn without ensuring 

a sufficient amount of contiguous or 

nearby habitat from which immigrants 

can re-inhabit burned areas or if not 

conducted with conservation of prairie 

invertebrates as a primary objective, fire 

is a current stressor that can have 

moderate impacts on populations. 

Uncontrolled wildfires may also have 

high or moderate levels of impacts to 

populations, and would also depend on 

the timing, intensity, and extent of the 

burn. Poweshiek skipperlings may be 

among the most sensitive of prairie 

butterflies to fire, and thus, coordination 

between habitat managers and butterfly 

experts is necessary to ensure that it is 

not implemented in a manner that 

degrades population viability. Fire is a 

current and ongoing stressor of high 

level of impact where burns occur 

without ensuring there is a sufficient 

amount of contiguous or nearby habitat 

from which immigrants can re-inhabit 

burned areas. Fire is an ongoing stressor 

rangewide for both species and has been 

documented at a high or moderate level 

of impact to populations at several sites 

in North Dakota, South Dakota, 

Minnesota, Wisconsin, and the Tallgrass 

Prairie Preserve in Manitoba. 

Grazing 

As with fire management, grazing may 

maintain habitat for the Poweshiek 

skipperling and Dakota skipper, but as 

with any management practice, 

appropriate timing, frequency, and 

intensity are important. The level of 

impact of grazing on Dakota skipper and 

Poweshiek skipperling populations also 

depends on the type of habitat that is 

being grazed. In contrast to the 

permanent habitat destruction and 

larval mortality caused by plowing or 

mining, for example, some habitats can 

remain suitable for the Dakota skipper 

and Poweshiek skipperling when grazed 

(Dana 1991, p. 54, Schlicht 1997, p. 5, 

Skadsen 1997, pp. 24–29), and native 

plant diversity in tallgrass prairie may 

recover from overgrazing if it has not 

been too severe or prolonged. In 

addition, grazing may be a valuable tool 

for controlling smooth brome invasion 

and maintaining native diversity in 

prairies, especially where circumstances 

make the use of fire difficult or 

undesirable (Service 2006, p. 2; Smart et 

al. 2013, pp. 685–686). Conversely, 

grazing may stimulate brome growth 

and reduce native plant diversity. 

Grazing may benefit the Dakota 

skipper and Poweshiek skipperling 

under some management scenarios (e.g., 

adaptive management to adjust grazing 

prescriptions according to their effects 

on essential features of the prairie 

ecosystem). In some habitats, Dakota 

skippers benefit from light grazing that 

minimizes the area dominated by tall 

grasses (e.g., big bluestem and 

indiangrass) (Dana 1991, p. 54). Dakota 

skippers were relatively abundant on 

prairies subjected to light grazing 

regimes, but absent on nearby idle 

prairies that were no longer used for 

grazing; moreover, more Dakota 

skippers were observed per hour on the 

lightly grazed prairies than on nearby 

habitat managed with fire (Schlicht 

1997b, p. 5). Similarly, in eastern South 

Dakota, Dakota skipper populations 

were deemed secure at some sites 

managed with rotational grazing light 

enough to maintain plant species 

diversity (Skadsen 1997, pp. 24–29), but 

the species was since extirpated at one 

site where a change in ownership 

resulted in significant overgrazing 

(Skadsen 2006b, p. 5). The economic 

benefit of grazing to ranchers may also 

benefit the species at some sites by 

deterring conversion of remnant prairies 

to row crop agriculture; however, recent 


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evidence indicates that conversion is 

more economically viable (Dowd 2013, 

pers. comm.). 

Bison (Bison bison) grazed at least 

some Dakota skipper and Poweshiek 

skipperling habitats historically 

(McCabe 1981, p. 190; Bragg 1995, p. 68; 

Schlicht and Orwig 1998, pp. 4, 8; 

Trager et al. 2004, pp. 237–238), but 

cattle (Bos taurus) are now the principal 

grazing ungulate in both species’ ranges. 

Bison and cattle both feed primarily on 

grass, but have some dissimilar effects 

on prairie habitats (Damhoureyeh and 

Hartnett 1997, pp. 1721–1725; Matlack 

et al. 2001, pp. 366–367). Cattle 

consume proportionally more grass and 

grasslike plants than bison, whereas 

bison consume more browse and forbs 

(flowering herbaceous plants) 

(Damhoureyeh and Hartnett 1997, p. 

1719). Grasslands grazed by bison may 

also have greater plant species richness 

and spatial heterogeneity than those 

grazed by cattle (Towne et al. 2005, pp. 

1553–1555). Both species remove forage 

for larvae (palatable grass tissue) and 

adults (nectar-bearing plant parts), 

change vegetation structure, trample 

larvae, and alter larval microhabitats. 

Livestock grazing was identified as a 

stressor to populations on most of the 

privately owned sites and some public 

sites on which Dakota skippers occurred 

in 2002 (Cochrane and Delphey 2002, 

pp. 62–69). Swengel and Swengel (1999, 

p. 286), for example, noted that at the 

Sheyenne National Grassland in North 

Dakota, grazing appeared to be 

unfavorable for the Poweshiek 

skipperling and Dakota skipper. 

Reduced availability of nectar 

resources and larval food plants is likely 

the primary factor leading to declines in 

Poweshiek skipperling and Dakota 

skipper populations on heavily grazed 

sites. In South Dakota, for example, 

Higgins (1999, p. 15) found lower plant 

diversity on privately owned prairies, 

which were mostly grazed, than on 

publicly owned prairies, which were 

almost all idle (no grazing or fire 

management). McCabe (1981, p. 189) 

observed that grazing eliminated Dakota 

skippers on North Dakota wet-mesic 

prairies; nectar plants such as yellow 

sundrops and bluebell bellflower 

rapidly diminished with light grazing, 

and heavy grazing eliminated upright 

prairie coneflower and purple 

coneflower. In Manitoba, certain levels 

of grazing are likely to adversely affect 

Dakota skipper populations in 

proportion to its intensity because it 

removes nectar sources (e.g., Rigney 

2013a, pp. 143 and 153). 

The intensity at which grazing occurs 

may dictate the level of impact to the 

Dakota skipper and Poweshiek 

skipperling, and grazing may have a 

larger impact on the Poweshiek 

skipperling than the Dakota skipper 

(Westwood 2013, pers. comm.). Grazing 

reduces Dakota skipper numbers in 

direct proportion to its intensity, due to 

the reduction in flowers that provide 

nectar and perhaps by influencing adult 

behavior (Dana 1997, p. 4). Dana (1997, 

p. 5) predicted that privately owned 

pastures in Minnesota’s Hole-in-theMountain complex, for example, will 

likely only support low densities of 

skippers if they continued to be heavily 

grazed and sprayed with herbicides. 

Surveys at this habitat complex in 2007, 

2008, and 2012 failed to record any 

Poweshiek skipperlings (Dana 2008, p. 

8; Selby 2009a, pp. xxxi–xxxii; Runquist 

2012a, pers. comm.; Runquist 2012, pp. 

13–14, 18–20), and Dakota skippers 

were not detected in 2012 surveys 

(Runquist 2012, pp. 13–14, 18–20; 

Runquist 2012a, pers. comm.). 

While most references to grazing 

impacts on prairie butterflies are based 

on ancillary observations made during 

research focused on other management 

impacts, one Minnesota study (Selby 

2006b) focused on the effects of grazing 

on all life stages of the Dakota skipper, 

and also included data for the adult 

stage of the Poweshiek skipperling. Both 

species were too scarce to collect data 

adequate to test the hypotheses (Selby 

2006b, p. 2), but observations based on 

2 years (2003 and 2004) of surveys 

suggested that numbers in the lightly to 

moderately grazed pasture were similar 

to those in the best portions of nearby 

ungrazed habitats (Selby 2006b, p. 30). 

Poweshiek skipperlings were almost 

absent from the study sites (Selby 

2006b, pp. iii–xxiii). Within the grazed 

study area, the number of Dakota 

skippers declined with increasing 

grazing intensity; Dakota skippers were 

absent from the most heavily grazed 

areas (Selby 2006b, p. 16). Skadsen 

(2001, p. 55) found that native forb 

diversity was poor on the grazed lands 

and predicted the extirpation of both 

species unless management practices 

were changed. The Dakota skipper is 

now extirpated at one of these sites, and 

its status is unknown at the other; 

Poweshiek skipperling status is 

unknown at both sites (Service 2014, 

unpubl. geodatabase). Spomer (2004, p. 

4) found that larval host plants and 

nectar sources were missing from 

heavily grazed pastures at Sheyenne 

National Grassland, North Dakota. 

Grazing intensity combined with 

varying habitat type may also affect the 

level of grazing impacts. On wet-mesic 

habitat in North Dakota, for example, 

Dakota skippers and Poweshiek 

skipperlings tolerate little to no grazing 

(McCabe and Post 1977, pp. 36–38; 

Royer and Marrone 1992a, pp. 10, 17, 

28; Royer and Marrone 1992b, pp. 17– 

18; Royer and Royer 1998, p. 22). 

Webster (2003, pp. 7–8) described very 

similar Dakota skipper habitats in 

Manitoba and, although grazing 

generally does not occur in these 

habitats that are occupied by Dakota 

skipper, they may be as sensitive to 

grazing as similar habitats in North 

Dakota; in a later report, he described 

the conversion of lands from haying to 

grazing as a major stressor to Dakota 

skipper in the wet-mesic habitats of 

Manitoba (Webster 2007, pp. i–ii, 6). 

More recently, it is thought that the 

effects of grazing in Manitoba and 

Saskatchewan, as stated in Webster 

(2007, entire), may not be applicable 

under current population sizes, and that 

even light grazing may be detrimental 

on dry short grass prairie sites prior to 

and during the Dakota skipper flight 

period (Westwood 2013, pers. comm.). 

In the drier and hillier habitats that 

the species inhabits, grazing may benefit 

Dakota skipper depending on its 

intensity. For example, in eastern South 

Dakota, Dakota skipper populations 

were deemed secure at some sites 

managed with rotational grazing that 

was sufficiently light to maintain native 

plant species diversity (Skadsen 1997, 

pp. 24–29), and grazing may also benefit 

Dakota skippers by reducing the area 

dominated by tall native grasses, such as 

big bluestem and Indiangrass (Dana 

1991). Proximity of nearby populations 

or contiguous habitat may alleviate 

some of the negative impacts of grazing. 

Royer and Marrone (1992b, p. 29; 1992a, 

p. 18) stated that heavy grazing was a 

stressor to Dakota skippers and 

Poweshiek skipperlings, but that 

occasional light grazing is not a longterm stressor in some habitats as long as 

there are areas of contiguous habitat that 

remain ungrazed. At Chekapa Creek 

Ridge and Knapp Pasture in South 

Dakota, heavy grazing apparently 

extirpated both the Poweshiek 

skipperling and Dakota skipper 

(Skadsen 2002, p. 38; 2004, p. 7; 2006a, 

p. 11). Due to its proximity to other 

Poweshiek skipperling populations and 

a return to fall haying in 2005, the 

Poweshiek skipperling recolonized 

Chekapa Creek Ridge in 2006 (Skadsen 

2006a, p. 12), but more recent surveys 

indicate that the Poweshiek skipperling 

has again been extirpated from this site 

due to habitat degradation because of a 

change from haying to grazing (Skadsen 

2012a, pers. comm., Skadsen 2012c, 

pers. comm.). 

As with fire, Dakota skipper and 

Poweshiek skipperling populations may 

persist through intense grazing episodes 


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or be restored afterwards, if sufficient 

numbers survive and reproduce in 

lightly grazed patches or if nearby 

habitats provide sufficient numbers of 

immigrants to reestablish the population 

after habitat quality is restored. Years of 

grazing without rest, however, may 

preclude recovery from the effects of 

intense grazing, although the capacity 

for restoration of suitable plant 

community and other habitat features 

may be highly variable among sites. On 

some sites, plant diversity may not be 

restored when grazing pressure declines 

(Dana 1997, p. 30; Jackson 1999, pp. 

134–135; Spomer 2004, p. 4). Grazing 

intensely (where a high proportion of 

plant biomass is removed) or for long 

duration leads to native plants being 

replaced with exotic, cool-season 

European forage grasses and legumes 

that are tolerant of continuous grazing 

(Jackson 1999, p. 128, Minnesota DNR 

2006, p. 232). In overgrazed native 

prairie in Minnesota, for example, the 

prairie is dominated by exotic grasses 

with a low native forb species diversity 

and abundance, and foliage height is 

less than 10 cm (4 in) (Dana 1997, p. 3); 

these prairies lack the native plants 

necessary to sustain adult and larval 

prairie butterflies. In comparison, sites 

less disturbed by grazing have a high 

native forb (nectar) species diversity and 

abundance foliage height is generally 

more conducive to perching and 

reproductive activities (between 25 and 

40 cm (10 and 16 in)) (Dana 1997, p. 2). 

Land managers also frequently use 

herbicides, often through broadcast 

application, to control weeds and brush 

on grazed remnant prairies, which 

further reduces native forb diversity and 

abundance (Dana 1997, p. 3; Stark et al. 

2012, pp. 25, 27) necessary for adult 

nectar sources. Skadsen (2006, p. 11), 

for example, documented the likely 

extirpation of Dakota skippers at Knapp 

Ranch in South Dakota after a July 2006 

application of broadleaf herbicide in 

concert with heavy grazing. Herbicide 

and pesticide use is discussed further 

under Factor E of this final rule. 

While reduced availability of nectar 

resources and larval food plants may be 

the primary factors leading to declines 

in Poweshiek skipperling and Dakota 

skipper populations on heavily grazed 

sites, changes in vegetation structure 

may also be important. For example, 

grazing prairie each year during midsummer eliminates nectar plants, such 

as purple coneflower, and native warmseason grasses that function as larval 

host plants (Skadsen 2007, pers. 

comm.). In South Dakota, vegetation 

height and litter depth were lower on 

prairie remnants that were mostly 

grazed (Higgins 1999, pp. 27–29). 

Grazing also causes direct mortality of 

larvae due to trampling and altering 

larval microhabitats (Royer et al. 2008, 

pp. 10–15). In North Dakota, grazing can 

compact soils in wet-mesic prairie 

inhabited by Dakota skippers and 

Poweshiek skipperlings, altering vertical 

water movement in the soil, which may 

lead to larval desiccation (Royer et al. 

2008, p. 16) and may inhibit subsurface 

shelter construction, potentially 

increasing larval vulnerability to 

predators, parasites, and other 

environmental stressors (Dana 2013, 

pers. comm.). Cattle may also kill larvae 

by trampling them, particularly in wetmesic prairies (McCabe 1981, p. 189). 

Livestock grazing is the predominant 

use of privately owned tallgrass prairie 

remnants in South Dakota (Higgins 

1999, p. 15) and was identified by the 

Service as a stressor on most of the 

privately owned sites on which Dakota 

skipper occurred when the species was 

identified as a candidate species in 2002 

(Cochrane and Delphey 2002, pp. 62– 

69). The presence and density of purple 

coneflower may serve as an indicator of 

grazing impacts to Dakota skippers and 

Poweshiek skipperlings where the 

species occur in dry-mesic prairie 

(Skadsen 2006a, p. 2); grazing from midJune through July may reduce purple 

coneflower abundance (Skadsen 2007, 

pers. comm.)—as discussed in the 

Background section of this rule, purple 

coneflower has been identified as a 

primary source of nectar for both 

species, particularly in dry prairie 

habitats. 

Britten and Glasford (2002, p. 373) 

recommended minimizing disturbance 

of Dakota skipper habitat during the 

flight period (late June to early July) to 

maximize genetically effective 

population sizes (the number of adults 

reproducing) to offset the effects of 

genetic drift of small populations 

(change in gene frequency over time due 

to random sampling or chance, rather 

than natural selection). Therefore, a 

large portion of the habitat of any 

Dakota skipper population should 

remain ungrazed or only lightly grazed 

during the flight period, and similar 

precautions should be taken for the 

Poweshiek skipperling. 

We assessed the level of impact to 

populations from grazing at 52 Dakota 

skipper sites and 16 sites currently 

occupied by Poweshiek skipperling 

with present or unknown status that had 

sufficient information to evaluate the 

stressor (Tables 3 and 4; Service 2012 

unpubl. data; Service 2014, unpubl. 

data). This analysis was conducted 

differently for different habitat types. 

For Type A habitat (Royer et al. 2008, 

pp. 14–16) where stocking rates 

(number of cattle or bison over a given 

area) have little or no evidence of 

grazing effects on Dakota skipper or 

Poweshiek skipper habitat quality, we 

found the level of impact to populations 

of grazing to be low. For Type B habitat 

(Royer et al. 2008, p. 14), we assumed 

that the level of impact of grazing to 

populations would be low if the drymesic slopes were grazed only before 

June 1 with at least one year of rest 

between rotations and if the pasture 

were only spot-sprayed with herbicides 

when and where necessary, or, the best 

available information does not indicate 

that grazing practices are degrading 

habitat quality for the species (i.e., no 

apparent diminishment of nectar plant 

density and diversity and habitat is 

good or excellent for Dakota skipper). 

At grazed sites where extirpation of 

the local population is not imminent, 

but habitat quality is fair to poor and the 

relative abundance of Dakota skippers 

or Poweshiek skipperlings is often low, 

we found the level of impact of grazing 

to populations to be moderate. Sites 

with a moderate level of impact to 

populations due to grazing may be 

lightly grazed for less than 4 months or 

less than 25 percent of the above-ground 

biomass of native grasses and forbs is 

consumed (Smart et al. 2011, pp. 182– 

183), are grazed after June 1, or are not 

given a year of rest between grazed 

years. At sites where grazing is 

conducted season-long, or for more than 

4 months during the year, or more than 

50 percent of the above-ground biomass 

of native grasses and forbs is consumed 

and herbicide use is frequent, we found 

the level of impact of grazing to 

populations to be high. At sites where 

grazing is a high-level stressor, 

extirpation of the population is likely 

imminent and habitat quality is poor. 

On public lands inhabited by the 

species, grazing is typically used to 

control nonnative cool-season grasses 

and invasive species. Cattle are often 

removed by July 1 to minimize adverse 

impacts to warm-season grasses, but this 

type of management minimizes the 

density of nectar species that are 

important to the Dakota skipper and 

Poweshiek skipperling. Invasive species 

are often present at grazed sites, which 

often leads to further management 

actions (see Invasive Species and 

Secondary Succession). 

Of the 52 Dakota skipper sites 

assessed, we found the level of impact 

to Dakota skipper populations from 

grazing to be high at 9 sites, moderate 

at 29 sites, and low at 14 sites (Service 

2012 unpubl. data; Service 2014, 

unpubl. data). Moderate- to high-level 

impacts to populations were primarily 

at South Dakota sites (N=27)—other 


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sites with moderate- to high-level 

impacts were in Minnesota (N=7), North 

Dakota (N=3), and Manitoba (N=1). As 

described above as part of our 

assessment of grazing, we examined the 

habitat quality ratings that were 

primarily assigned by researchers 

during surveys for the species, during 

separate habitat assessments, or that 

were available from State heritage 

databases or other sources of scientific 

data. The habitat quality was rated as 

poor at 7 of the 9 sites where grazing 

poses a high level of impact to Dakota 

skipper populations. At each of the 14 

sites where grazing pressure is low, 

habitat quality was good or excellent, 

with two exceptions where habitat was 

rated as fair to good. Among the 29 sites 

where grazing is a moderate level of 

impact to Dakota skipper populations, 6 

had habitat rated good or excellent. 

Of the 16 Poweshiek skipperling sites 

for which we had sufficient information 

to assess grazing, the level of impact to 

populations from grazing is high at 4 

sites, moderate at 10 sites, and low at 2 

sites—all but 2 of these sites were in 

South Dakota. No sites in Wisconsin or 

Michigan were assessed for grazing 

impacts to populations, where the 

grazing does not occur. Among the 10 

sites where grazing is a moderate level 

of impact to Poweshiek skipperling 

populations, 8 have habitat rated as fair 

to excellent. The habitat quality was 

rated as poor at 2 of the 4 sites where 

grazing is having a high level of impact 

to Poweshiek skipperling populations. 

In summary, grazing may benefit 

Dakota skippers and Poweshiek 

skipperlings in native tallgrass prairie 

by increasing native plant diversity and 

patchiness of fires (Minnesota DNR 

2006, p. 232). The economic benefit of 

grazing to ranchers may also be a benefit 

to the species by deterring conversion of 

remnant prairies to row crop 

agriculture. Grazing is a stressor to these 

species, however, if it is not managed 

with the goal of conserving nativeprairie vegetation that comprises 

suitable habitat for Dakota skipper and 

Poweshiek skipperling. Dakota skippers 

and Poweshiek skipperlings may benefit 

when prairie habitat is rested from 

grazing for at least a part of each 

growing season, if livestock are 

precluded from removing too much 

plant material (e.g., are moved when 

stubble heights are 6–8 in (15–20 cm) 

(Skadsen 2007, pers. comm.), and if the 

timing of grazing for each field varies 

from year to year (Skadsen 2007, pers. 

comm.). Grazing management 

recommendations may not be 

universally applicable to all locations, 

and may depend on the habitat type and 

other ecological and physical conditions 

of the site. For instance, stubble heights 

of 6–8 inches may be difficult to attain 

in certain dry-mesic sites (ND NRCS 

2013, pers. comm.). 

Conversely, Dakota skipper and 

Poweshiek skipperling populations may 

be reduced or extirpated when too much 

plant material is removed, when fields 

are not rested for some portion of the 

growing season, or fields are grazed 

during the same period each year. 

Grazing poses a current and ongoing 

stressor of moderate to high level of 

impact to populations where its 

intensity is such that Dakota skippers 

and Poweshiek skipperlings are unlikely 

to thrive or even persist. Grazing poses 

a likely future stressor where current 

management is conducive to Dakota 

skipper or Poweshiek skipperling 

conservation, but where landowners 

may allow excessive grazing in the 

future, for example, where management 

may change as a result of the changing 

market prices of agricultural products. 

Unsuitable grazing is an ongoing 

stressor throughout much of the range of 

the Dakota skipper and Poweshiek 

skipperling (primarily in flat wet 

prairies of Minnesota, North Dakota, 

and South Dakota); grazing is not a 

documented stressor at the Poweshiek 

skipperling sites with present or 

unknown status in Wisconsin, 

Michigan, and Iowa or at most Dakota 

skipper sites in Canada. 

Haying 

As with grazing and fire, haying 

(mowing grasslands and removing the 

cuttings) may maintain habitat for the 

Poweshiek skipperling and Dakota 

skipper, but as with any management 

practice, appropriate timing, frequency, 

and intensity are important. Poweshiek 

skipperling habitat at Scuppernong 

Prairie in Wisconsin, for example, 

would have succeeded to shrubby or 

forested habitat if it had not been hayed 

each fall (Borkin 2011, in litt.)—it is 

now one of the few sites in Wisconsin 

that is occupied by the Poweshiek 

skipperling. Nearly all of the Dakota 

skipper sites in Canada where the 

species is present are privately owned, 

fall-hayed prairies (Westwood 2013, 

pers. comm.). 

Haying generally maintains prairie 

vegetation structure, but it may favor 

expansion of invasive species such as 

Kentucky bluegrass. If done during the 

adult flight period, haying may kill the 

adult butterflies or cause them to 

emigrate, and if done before or during 

the adult flight period, it may reduce 

nectar availability (McCabe 1979, pp. 

19–20; McCabe 1981, p. 190; Dana 1983, 

p. 33; Royer and Marrone 1992a, p. 28; 

Royer and Marrone 1992b. p. 14; 

Swengel 1996, p. 79; Webster 2003, p. 

10). Royer and Marrone (1992b, p. 14), 

for example, ascribed the loss of a North 

Dakota Poweshiek skipperling 

population to June and July haying. 

Several years of July haying may have 

led to the Poweshiek skipperling’s 

extirpation at Wakidmanwin Prairie in 

South Dakota (Skadsen 2006b, p. 13). 

The Dakota skipper was observed at the 

Wakidmanwin Prairie in 2010 (Skadsen 

2010, p. 6); however, it is not clear if the 

management has changed since the 

observation. Early June haying may have 

eliminated Dakota skippers from at least 

one site in North Dakota (Royer and 

Royer 2012a, p. 72). 

Hayed prairies are important 

reservoirs of native-prairie plant 

diversity; however, long-term annual 

haying negatively impacts prairie plant 

diversity (Jog et al. 2006, pp. 164–165). 

Jog et al. (2006, pp. 164–165) 

recommended diversifying management 

to include, for example, periodic fire 

and to forego annual haying to increase 

plant species diversity. In a long-term 

study of a prairie in southeastern 

Wisconsin, a switch from late-season 

haying to fire management led to 

increased native plant diversity and 

coverage of warm-season grasses, 

although woody plant species also 

increased (Rooney and Leach 2010, p, 

319)—this increased plant diversity was 

likely an expression of plants that were 

already at that location. 

Late-season haying may benefit 

Dakota skipper populations (McCabe 

1981, p. 190), and Dakota skipper 

populations might be more common on 

hayed prairies than on idle (not hayed) 

prairies (Webster 2003, p. 10). Swengel 

and Swengel (1999, p. 279) observed 

significantly greater relative abundance 

of Dakota skippers on hayed tracts 

compared with either idle or burned 

tracts in Minnesota, and Skadsen (2004, 

p. 7) documented the extirpation of 

Dakota skippers from a site after its 

management switched from haying to 

intensive grazing. Some remnant Dakota 

skipper populations in the eastern 

Dakotas are found on fall-hayed prairies 

(Skadsen 1997, pp. 10–23; Royer and 

Royer 2012b) as are many of the sites in 

Manitoba (Webster 2003, p. 10). Webster 

(2003, p. 8) found ‘‘healthy 

populations’’ of Dakota skippers in 

Manitoba on sites used as hay fields, as 

described by the absence of standing 

dead grass, low numbers of shrubs, 

shorter bluestem grasses, and abundant 

and readily observable nectar flowers, as 

compared to un-hayed sites. Scarlet 

Fawn Prairie in South Dakota, which is 

hayed in the fall, is considered one of 

the highest quality prairies in that State 

(Skadsen 2012, pers. comm.). In the 


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Dakotas, late-season (mid-August to 

October) haying appears to minimize 

impacts to the prairie butterflies, 

although annual haying may diminish 

the vigor of native, warm-season grasses 

and reduce forb density in north-central 

North Dakota (wet-mesic) habitats (Lenz 

1999, p. 14; Skadsen 2009, p. 8). 

Consistent late-season haying of 

Poweshiek skipperling habitat in South 

Dakota, appears to have facilitated the 

expansion of green needlegrass (Stipa 

viridula), a cool-season grass, and 

prevented seed development in warmseason plants (Skadsen 2009, p. 8). 

We assessed the level of impact of 

haying to populations at 41 Dakota 

skipper sites and 6 Poweshiek 

skipperling sites with present or 

unknown status where we had sufficient 

information to assess the stressor 

(Tables 3 and 4; Service 2012 unpubl. 

data; Service 2014, unpubl. data). 

Haying was considered to be a stressor 

with a low or no negative impact on 

populations where it is implemented 

after the flight period (after 

approximately August 1) and when 

there is no reduction in the availability 

of native plant species. Haying was 

considered to be a stressor with a 

moderate level of impact on 

populations, where the exact timing or 

extent of haying was unknown, but 

there are: (1) One or more indications 

that haying is resulting in a reduction in 

nectar or larval food sources important 

to the species due to timing or 

frequency of mowing; (2) part of the 

Dakota skipper or Poweshiek 

skipperling habitat on the site is hayed 

before August 1, but a substantial 

proportion of habitat is not hayed and 

not clearly subject to other stressors, 

such as frequent fire or grazing (e.g., 

Smokey Lake site, North Dakota); or (3) 

where haying occurs before or after 

August 1, but the site is hayed no more 

frequently than once every 3 years (e.g., 

Roy West Game Production Area, South 

Dakota). 

We considered haying to be a stressor 

with a high level of impact on 

populations where the site was hayed 

prior to August 1 (e.g., Oaks Prairie, 

North Dakota). At 29 of the 41 evaluated 

Dakota skipper sites, current haying 

practices are conducive (beneficial) to 

Dakota skipper conservation, because it 

is conducted after August 1 and is not 

reducing native plant species diversity. 

One or more indications that current 

haying practices are slowly degrading 

habitat quality for Dakota skippers has 

been documented at 11 of the 41 sites. 

At several sites in North Dakota, for 

example, Royer and Royer (2012b, pp. 

15, 21, 24, 45) noted a decrease in the 

diversity and density of forbs at sites 

hayed annually. Haying is a stressor 

with a high level of impact on 

populations at 1 of the 41 Dakota 

skipper sites assessed and a stressor of 

moderate-level impacts to the 

populations at 11 of the 41 Dakota 

skipper sites assessed. Of the 6 

Poweshiek skipperling sites evaluated, 

haying was a stressor with moderatelevel impacts on populations at 3 sites 

and was not considered to have highlevel impacts to the populations at any 

of the 6 sites. 

In summary, haying is a current and 

ongoing stressor of moderate to high 

level of impacts to Dakota skippers and 

Poweshiek skipperlings at the few sites 

where the site is normally hayed before 

August and where annual haying is 

reducing availability of larval food and 

adult nectar plants. However, fall 

haying is beneficial to both species, 

specifically if it is conducted after the 

flight period (after August 1), no more 

than every other year, and there is no 

indication that native plant species 

diversity is declining due to timing or 

frequency of haying. Haying is a current 

stressor at a small number of sites for 

both species; these sites occur primarily 

in North Dakota and South Dakota. 

Lack of Disturbance 

While inappropriate or excessive 

grazing, haying, and burning are 

stressors to some Poweshiek skipperling 

and Dakota skipper populations and 

have led to the extirpation of others, 

both species are also subject to the stress 

of no management practices being 

implemented. Prairies that lack periodic 

disturbance become unsuitable for 

Poweshiek skipperlings and Dakota 

skippers due to expansion of woody 

plant species (secondary succession), 

litter accumulation, reduced densities of 

adult nectar and larval food plants, or 

invasion by nonnative plant species 

(e.g., smooth brome) (McCabe 1981, p. 

191; Dana 1983, p. 33; Dana 1997, p. 5; 

Higgins et al. 2000, p. 21; Skadsen 2003, 

p. 52). For example, Dakota skipper 

numbers were reduced at Felton Prairie, 

Minnesota, in tracts that had not been 

hayed or burned for several years 

(Braker 1985, p. 47). Another study also 

observed significantly lower Dakota 

skipper abundance on unmanaged or 

idle sites, compared with hayed sites; 

however, Poweshiek skipperlings were 

significantly denser with idling 

(Swengel and Swengel 1999, p. 285). 

Skadsen (1997, pp. 10–23; 2003, pp. 8, 

35, 42) reported deterioration of several 

unburned and unhayed South Dakota 

prairies in just a few years due to 

encroachment of woody plants and 

invasive species and found lower 

species richness of prairie-dependent 

butterflies and lower floristic quality at 

sites with no disturbance versus sites 

managed by grazing or fall haying 

(Skadsen 2006a, p. 3). For example, 

Dakota skippers returned to an idle site, 

Pickerel Lake State Park, after a burn 

conducted in 2007 resulted in a 

significant increase in forbs, particularly 

purple coneflower (Skadsen 2008, p. 2). 

In a separate study, Higgins et al. (2000, 

p. 24) found that prairie habitats left 

idle had lower plant diversity and 

quality than prairies managed with fire. 

Populations of Dakota skippers and 

Poweshiek skipperlings may also be at 

risk at sites where a private landowner 

is not aware of the presence or potential 

presence of the species, but would 

conserve the land if they were made 

aware. The land use in some areas in 

Canada, for example, are currently 

inadvertently used in ways that are 

favorable to the species (for example, 

fall haying), but the land use may 

change in the future (Westwood 2014, 

pers. comm.). In the United States, the 

Service has notified private landowners 

of the presence or potential presence of 

one or both species on their land at most 

sites with present or unknown 

occupancy and many sites that are 

considered extirpated or possibly 

extirpated but still may have suitable 

habitat. 

We assessed the stressor posed by 

lack of management for populations at 

17 Dakota skipper sites and 12 

Poweshiek skipperling sites with 

present or unknown status where we 

had sufficient information to evaluate 

the stressor (Tables 3 and 4; Service 

2012 unpubl. data; Service 2014, 

unpubl. data). Lack of management was 

considered to be a stressor of moderatelevel impacts to the population where 

the species’ habitat is degraded or likely 

to become degraded due to secondary 

succession, invasive species, or both, 

but actions to restore habitat quality are 

planned or ongoing, or where the site is 

idle with no evident plans to initiate 

management (e.g., fire, grazing, haying), 

and there are signs of ongoing or 

imminent secondary succession. Lack of 

management was considered to be a 

stressor with a high level of impact to 

the population where the habitat quality 

at a site is degraded or likely to become 

degraded due to secondary succession 

or invasive species, and there are no 

ongoing or planned actions to maintain 

or restore habitat quality. Lack of 

management was considered to be a 

stressor of low-level impacts to Dakota 

skipper or Poweshiek skipper 

populations at sites that are managed by 

grazing, haying/mowing, or fire that 

precludes loss of Dakota skipper or 

Poweshiek skipperling habitat to 


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secondary succession and invasive 

species (e.g., smooth brome). 

Nine of the 17 Dakota skipper sites 

assessed are under high level of impact 

to population due to lack of 

management and 5 sites are under 

moderate level of impact to the 

population. Four of the 12 Poweshiek 

skipperling sites assessed are under 

high level of impact to the population 

due to lack of management, and 6 sites 

are under moderate level of impact to 

the population. The Dakota skipper and 

Poweshiek skipperling are unlikely to 

persist at those sites where the level of 

impact to the population due to lack of 

management is high. Sites currently 

under stress by lack of management 

occur throughout the range of both 

species; however, most of the present or 

unknown sites that lack appropriate 

management are in North Dakota, South 

Dakota, Minnesota, and Michigan. In 

summary, lack of disturbance is a 

current and ongoing stressor to Dakota 

skipper and Poweshiek skipperling 

populations where woody vegetation or 

invasive species expansion will reduce 

native-prairie grasses and flowering 

forbs. 

Summary of Factor A 

We identified a number of stressors to 

the habitat of the Dakota skipper and 

Poweshiek skipperling that operated in 

the past, are impacting both species 

now, and will continue to impact the 

species in the future. The decline of 

both species is the result of the longlasting effects of habitat loss, 

fragmentation, degradation, and 

modification from agriculture, 

development, invasive species, 

secondary succession, grazing, and 

haying. Although efforts have been 

made to effectively manage habitat in 

some areas, the long-term effects of 

large-scale and wide-ranging habitat 

modification, destruction, and 

curtailment will last into the future. 

Invasion of the species’ habitat by exotic 

species and woody vegetation, 

overgrazing, long-lasting or permanent 

alterations in water levels or hydrology, 

and too frequent or improperly timed 

haying remove or significantly reduce 

the availability of plants that provide 

nectar for adults and food for larvae. 

Fire and flooding cause direct mortality 

or destroy nectar and food plants if the 

intensity, extent, or timing is not 

conducive to the species’ biology. 

Of the 160 Dakota skipper sites we 

evaluated for one or more habitat 

stressors, at least 131 sites have at least 

one documented stressor with moderate 

to high levels of impact to 

populations—these sites are found 

across the current range of the species 

in Minnesota, North Dakota, South 

Dakota, Manitoba, and Saskatchewan 

(Service 2012 unpubl. data; Service 

2014, unpubl. data). Fifty-eight sites 

have 2 or more documented stressors of 

moderate to high levels of impact to 

populations, and 24 sites have 3 or more 

documented stressors of moderate to 

high level of impact to populations. 

Sites with three or more stressors are 

found across most of the current range 

of the species; these sites occur in 

Minnesota, North Dakota, South Dakota, 

and Manitoba (Service 2012 unpubl. 

data; Service 2014, unpubl. data). 

Furthermore, concurrently acting 

stressors may have more intense effects 

than any one stressor acting 

independently. Therefore, based on our 

analysis of the best available 

information, present and future loss and 

modification of Dakota skipper habitat 

is a stressor that has significant impacts 

on populations of the species 

throughout all of its range. Habitatrelated stressors occur at sites with 

Dakota skipper populations within 

every State and province of occurrence. 

Similarly, of the 60 Poweshiek 

skipperling sites with present or 

unknown status that we analyzed for 

one or more habitat stressors, 46 of them 

have at least one stressor at moderate to 

high levels of impact to the population. 

These sites are found across the current 

range of the species and occur in Iowa, 

Michigan, Minnesota, North Dakota, 

South Dakota, Wisconsin, and Manitoba 

(Service 2014, unpubl. data). Twentyfive sites have 2 or more documented 

stressors that have moderate to high 

levels of impact to the population. 

These sites are found across the current 

range of the species and occur in Iowa, 

Michigan, Minnesota, North Dakota, 

South Dakota, Wisconsin, and Manitoba 

(Service 2014, unpubl. data). Eleven of 

them have at least three documented 

stressors that have moderate to high 

levels of impact to the population. 

These sites are found across the current 

range of the species and occur in Iowa, 

Michigan, Minnesota, South Dakota, 

and Manitoba (Service 2014, unpubl. 

data). Furthermore, concurrently acting 

stressors may have more intense effects 

than any one stressor acting 

independently. Therefore, based on our 

analysis of the best available 

information, present and future loss and 

modification of Poweshiek skipperling 

habitat is a stressor that has significant 

impacts on the species throughout its 

range. 

Conservation Efforts To Reduce Habitat 

Destruction, Modification, or 

Curtailment of Its Range 

In the past, funding for conservation 

of rare species was primarily directed 

toward federally listed or candidate 

species, so while the Poweshiek 

skipperling may have benefited 

indirectly from conservation activities 

focused on species such as the Dakota 

skipper and Mitchell’s satyr 

(Neonympha mitchellii mitchelli), it has 

not generally been the primary focus of 

those activities. As a result, survey data 

and incidental life-history observations 

have been accumulated as a part of 

projects focused on other species, but 

surveys were not necessarily focused on 

Poweshiek skipperling sites and 

detailed life-history, population, and 

demographic data have generally not 

been collected for the species. Various 

conservation activities directed at the 

Dakota skipper also indirectly benefit 

the Poweshiek skipperling; these 

activities are summarized below. 

Conservation agencies have 

recognized the need to address the 

status of prairie butterflies for more than 

30 years beginning with a 1980 

workshop held to initiate studies of 

Dakota skippers and other prairie 

butterflies. In June 1995, the U.S. Fish 

and Wildlife Service convened Dakota 

skipper experts to outline tasks needed 

to preserve enough viable populations 

to ensure long-term security for the 

species. The group outlined a plan for 

surveying populations and 

characterizing sites and habitats at 

priority areas, identifying and 

recommending management needs, 

monitoring, and outreach and 

education; however, this plan was not 

drafted or finalized. In 1999, a Dakota 

skipper recovery strategy meeting was 

held in South Dakota with State, 

Federal, and nongovernmental 

biologists attending (Skadsen 1999b, 

entire). In 2011, researchers in Canada 

organized a Poweshiek Skipperling 

Workshop and followup conference call 

that brought together researchers and 

managers from across the range of the 

Poweshiek skipperling to provide 

updates on survey data, discuss ongoing 

activities, and plan future work. The 

workshop resulted in specific 

conservation action plans for the 

species. The Minnesota Zoo organized a 

followup conference during March 2013 

to assess progress of the 2011 Poweshiek 

Skipperling Workshop Action Plans, 

facilitate discussion on the potential 

effects of management activities on 

prairie butterflies, identify needed 

information and data gaps, establish 

new priorities for research and a draft 


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action plan for 2013, and facilitate 

networking and collaborations focused 

on the conservation of the Dakota 

skipper and Poweshiek skipperling, as 

well as other tallgrass prairie butterflies 

in the Midwest—the Northern Tallgrass 

Prairie Lepidoptera Conservation 

Conference Working Group Report 

Synthesis is posted at http:// 

www.mnzoo.org/Prairie

LepidopteraConference/Northern%

20Tallgrass%20Prairie%

20Lepidoptera%20Conservation%

20Conference%20Working%20Group%

20Reports%20-%20Synthesis.pdf. 

Research and survey work has 

occurred throughout the range of both 

species to document populations, to 

study the life history of both species, 

and to examine the effects of various 

management practices, such as fire and 

grazing, on the species and their habitat. 

For example, research and survey work 

on Dakota skippers began with Dana’s 

(1991, entire) doctoral study on fire 

effects at Hole-in-the-Mountain, 

Minnesota, beginning in 1978 and 

McCabe’s (1981, entire) 1979 surveys for 

the Garrison Diversion project in North 

Dakota. Additional work has been 

completed on characterizing habitat at 

important Dakota skipper sites in 

Minnesota (Dana 1997, entire) and 

North Dakota (Lenz 1999, entire, Royer 

and Royer 1998, entire, Royer and Royer 

2012a, entire). Royer (2008, entire) 

assessed abiotic habitat parameters of 

soil in relation to management and 

conservation of Dakota skippers to 

complement prior floristic 

characterization of these habitats. The 

Minnesota DNR and the Service 

planned to cooperatively study the 

effects of grazing on the Dakota skipper 

and Poweshiek skipperling (Selby 2003, 

entire; Selby 2006b, entire); however, 

skipper numbers were too low to collect 

sufficient data to test hypotheses (Selby 

2006b, p. 30). 

In the past, the Service funded some 

management activities intended to 

benefit the Dakota skipper, including 

habitat management at Big Stone 

National Wildlife Refuge, Minnesota 

(Olson 2000, entire), landowner contacts 

and education on conservation practices 

in South Dakota (Skadsen 1999b, 

entire), and prairie vegetation 

restoration at Chippewa Prairie in 2000 

and at Twin Valley Prairie SNA, 

Minnesota, in 2001. The results of these 

efforts are varied; for instance, the 

prairie habitat at Twin Valley Prairie 

SNA was recently rated as excellent 

quality (Service 2014, unpubl. 

geodatabase), but the status of both 

species at that site is unknown; the last 

positive observation of Dakota skippers 

and Poweshiek skipperlings was 1993 

and 1994, respectively. The Dakota 

skipper is extirpated from Chippewa 

Prairie, and the status of the Poweshiek 

skipperling is unknown at the site; the 

last positive observations of the species 

were in 1995 and 1994, respectively 

(Service 2014, unpubl. geodatabase). 

The Service purchases easements to 

prevent prairie conversion for 

agriculture and provide cost-share to 

support rotational grazing and other 

practices that may benefit Dakota 

skippers and Poweshiek skipperlings. 

For example, in 12 counties in South 

Dakota within the range of the species, 

the Service’s grassland easement 

program has protected 365,193 ac 

(147,788 ha) of grassland that are 

primarily native prairie (Larson 2013, 

pers. comm.; HAPET 2012, unpubl. 

data), although it is not clear whether 

these lands are suitable habitat for either 

species. Other Service fee title lands, 

State lands, and Natural Resources 

Conservation Service (NRCS) easement 

lands may also protect areas from 

conversion, depending on the 

protections in those areas (Larson 2013, 

pers. comm.). If easements are near 

prairie butterfly habitat they can 

minimize the impacts of conversion and 

may provide dispersal corridors or 

buffer sites from external stressors (e.g., 

pesticide drift). 

Prairie easements generally prevent 

grasslands from being plowed or 

destroyed and prevent haying before 

July 16, but may not restrict grazing, 

pesticide use, or other practices that can 

degrade the status of Dakota skipper or 

Poweshiek skipperling populations. For 

example, one property with a Service 

easement was recently overgrazed to the 

extent that Dakota skipper was 

extirpated from the site (Skadsen 2006b, 

p. 5). Cost-share partnerships on 

easements and other areas, however, 

may further enable landowners to 

manage grasslands to benefit Dakota 

skippers and other prairie endemic 

species. The Service may implement 

such actions through the Partners for 

Fish and Wildlife program or in 

collaboration with NRCS or other 

agencies. Since 1990, the Service has 

purchased easements to prevent 

grassland conversion on millions of 

acres in Minnesota, North Dakota, and 

South Dakota (HAPET 2012, unpubl. 

data). Only some of these areas include 

Dakota skipper or Poweshiek 

skipperling sites, are within the range of 

either species, or include suitable 

habitat for either species. 

Conservation-interested agencies, 

individuals, and Tribes in South Dakota 

have made concerted efforts for decades 

to conserve native prairie within the 

Dakota skipper range. For example, 

there are approximately 54,000 ac 

(21,853 ha) of fee title lands in grassland 

that are managed by the Service in 12 

of the counties within the historical or 

current range of the Dakota skipper and 

365,000 ac (147,710 ha) protected by the 

Services’ grassland easement program 

(HAPET 2012, unpubl. data; Larson 

2013, pers. comm.). These acreages do 

not include an additional 4,000 ac 

(1,619 ha) of grass protected by 

acquisitions that have occurred in 2012 

(HAPET 2012, unpubl. data; Larson 

2013, pers. comm.). Not all of these 

lands, however, may be managed in 

such a manner that is conducive to 

Dakota skipper populations. 

About one-half of the present or 

unknown Dakota skipper sites (total 

number of present/unknown sites is 

171) in the United States are privately 

owned (excluding populations on land 

owned by The Nature Conservancy). 

Twelve of these populations are on 

private land on which the Service has 

purchased conservation easements that 

preclude plowing and haying before 

July 16. Manitoba Habitat Heritage 

Corporation has an easement that 

overlaps with one Dakota skipper site in 

Canada (Friesen 2013, pers. comm.). 

Similarly, of the 70 privately owned 

sites where Poweshiek skipperling has 

been recorded since 1985, 8 sites (all in 

Minnesota) have conservation 

easements. These easements do not 

prescribe grazing practices but are 

intended to prevent grassland 

conversion to cropland, which is 

detrimental to Dakota skippers or 

Poweshiek skipperlings. Additional 

measures on some easement properties 

could ensure grazing practices do not 

inadvertently impact either species. 

The Nature Conservancy’s Minnesota 

and Dakotas offices initiated a Prairie 

Coteau Coordinated Conservation 

Planning Effort and Plan in 1998 to 

facilitate conservation actions by 

various landowners, including private, 

county, state, tribal and Federal, on high 

biodiversity prairie sites (Skadsen 

1999b, entire). Additional partners 

include conservation organizations, 

local conservation districts, and 

universities. The Nature Conservancy 

acquired a reserve in the Sheyenne 

Grassland area, Brown Ranch, which is 

a Dakota skipper site with an unknown 

status, and manages some of the most 

significant habitats for the two species 

in Minnesota, including the Hole-in-theMountain Prairie preserve. Based on 

intensive surveys in 2007, Dana (2008, 

p. 19) found ‘‘considerable reassurance’’ 

that the rotational burning approach 

used at Prairie Coteau SNA and Hole-inthe-Mountain Preserve is compatible 

with long-term persistence of the Dakota 


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skipper, for example, by controlling 

woody vegetation encroachment. The 

Minnesota DNR also manages the Prairie 

Coteau SNA with rotational burning 

(Dana 2008, p. 19), which may control 

woody vegetation encroachment. The 

Clay County Stewardship Plan (Felton 

Prairie Stewardship Committee 2002) 

may have reduced the likelihood and 

severity of gravel mining within the 

Felton Prairie complex in Minnesota. 

Many of the best sites for Dakota 

skipper and Poweshiek skipperling in 

South Dakota are on tribal lands 

managed by the Sisseton-Wahpeton 

Sioux Tribe (e.g., Scarlet Fawn and Oak 

Island Prairies) (Skadsen 1997, Skadsen 

2012b, p. 3), with late-season haying. 

According to Skadsen (2012, p. 3) ‘‘. . . 

as in prior years, the fall hayed prairies 

held in trust by the Sisseton Wahpeton 

Oyate had the most diverse native flora 

and thus the largest numbers of Dakota 

skippers.’’ Although these lands 

generally contain high-quality habitat 

for prairie butterflies in eastern South 

Dakota (Skadsen 2012b, p. 3), a change 

to alternate year haying—instead of 

annual haying—may further improve 

habitat quality by ensuring that plants 

that flower during the Dakota skipper 

and Poweshiek skipperling flight 

periods are able to produce seed (Royer 

and Royer 2012b, p. 15). 

The Day County Conservation 

District, South Dakota, places a high 

priority on implementing prescribed 

grazing on rangelands known to support 

Dakota skippers and bordering sites in 

the Upper Waubay Basin Watershed 

(Skadsen 1999b, p. 3). Their efforts 

include soliciting grants and providing 

education on grazing management, 

controlled burning, and integrated pest 

management to control leafy spurge, 

through workshops and a demonstration 

site. There are five Poweshiek 

skipperling sites in Day County with 

unknown occupancy and no sites where 

the species is considered to be present. 

There are a total of 24 Dakota skipper 

sites in Day County: 3 sites where the 

species is considered to be present, 11 

sites that have an unknown occupancy, 

and the remaining are extirpated or 

possibly extirpated. It is not known how 

many of these sites are benefiting from 

these efforts and to what degree. 

In South Dakota, completed 

management plans guide habitat 

restoration at Hartford Beach State Park 

and Pickerel Lake State Recreation Area 

(Skadsen 2008, pp. 4–7; Skadsen 2011, 

pp. 1–4). At each site, the lack of 

haying, grazing, or fire had allowed 

plant succession to degrade and reduce 

the extent of Dakota skipper habitat. 

Dakota skipper habitat at these sites is 

divided into 3–4 management units. A 

controlled burn was conducted in one 

unit at Hartford Beach State Park in 

2008, and shrubs were removed from 

two of the units (Skadsen 2008, p. 4). At 

Pickerel Lake State Recreation Area, a 

controlled burn was conducted in 2007, 

and in 2008 the site was hayed and 

shrubs were removed. The Dakota 

skipper was present in the burned unit 

for the first time since 2002 after ‘‘a 

dramatic increase in forbs, especially 

purple coneflower, occurred after the 

burn’’ and ‘‘apparently attracted Dakota 

skippers from a nearby site’’ (Skadsen 

2008, p. 2). The Poweshiek skipperling 

is extirpated from both sites, but the 

reasons for its disappearance are not 

known (Service 2012, unpubl. data). At 

each site, prescribed fire and brush 

control are implemented on a rotational 

basis (Skadsen 2011, pp. 1–4); at 

Pickerel Lake State Recreation Area, 

forbs were planted in 2011 to diversify 

nectar resources for prairie butterflies 

(Skadsen 2011, pp. 2–4). 

A privately owned ranch with Dakota 

skippers in Day County, South Dakota, 

is managed with a patch-burn grazing 

system in which each grazing unit is 

rested for a full year (Skadsen 2008, p. 

10), which may be beneficial to the 

species. The effects of patch-burn 

grazing at this site are being studied 

jointly by The Nature Conservancy and 

South Dakota State University (Skadsen 

2008, p. 10). 

In 2005, the Service’s National 

Wildlife Refuge System in North Dakota 

and South Dakota adopted the 

Conservation Strategy and Guidelines 

for Dakota Skippers on Service Lands in 

the Dakotas, which are based on the 

Service’s Dakota Skipper Conservation 

Strategy and Guidelines and on versions 

of the Service’s conservation guidelines 

for Dakota skipper. The guidelines were 

revised in March 2013 (http://

www.fws.gov/midwest/endangered/

insects/dask/DASKconservation

guidelines2013.html). In the Dakotas, 

the Service plans to implement the 

conservation guidelines on all of its 

lands where the Dakota skipper is 

known to occur—the Service owns 12 

Dakota skipper sites in the Dakotas 

where the species is considered present 

or has unknown occupancy. The 

guidelines also suggest that the Service 

examine other lands under its 

ownership to determine whether 

unrecorded populations of Dakota 

skippers may be present and to conduct 

surveys in those areas or manage the site 

in accordance with the Dakota Skipper 

Conservation Strategy and Guidelines. 

These guidelines will be reviewed and 

updated to reflect new information as it 

is developed. 

In Manitoba, August 1st is the 

recommended earliest haying and 

grazing date at Dakota skipper sites. The 

recommended intensity of grazing is to 

be as low as economically feasible to 

prevent permanent damage to sites (e.g., 

destruction of nectar plants). In 

Manitoba, it is recommended that sites 

that have burned or have been impacted 

by other factors such as extensive 

flooding, should not be grazed for at 

least one year following these events. 

Poweshiek Skipperling 

Most of the conservation initiatives 

discussed above were put in place to 

benefit the Dakota skipper, but may also 

benefit the Poweshiek skipperling. 

Conservation initiatives are also in place 

at several Poweshiek skipperling sites in 

Wisconsin and one or two sites in 

Michigan. 

At least two sites occupied by 

Poweshiek skipperling in Michigan are 

at least partially owned and managed by 

the Michigan Nature Association 

(MNA); however, the MNA does not 

specifically manage for Poweshiek 

skipperling conservation. The State of 

Michigan owns part or all of four 

occupied Poweshiek skipperling sites; 

however, most of those lands are 

managed as State recreational areas, not 

for prairie butterfly conservation. 

Landowners at one fen site are 

participating in a Michigan DNR Land 

Incentive Program, and a portion of 

another occupied site is part of the Burr 

Memorial Prairie Plant Preserve 

(Michigan Natural Features Inventory 

2011, unpubl. data). The Poweshiek 

skipperling may benefit from 

conservation activities in place for the 

federally endangered Mitchell’s satyr at 

one Michigan site. 

Poweshiek skipperling sites in 

Wisconsin are owned and managed by 

the Wisconsin DNR, who manage the 

land to maintain and improve prairie 

habitat. The Wisconsin DNR recently 

received a Sustain Our Great Lakes 

(SOGL) grant to conduct invasive 

species management on several SNAs, 

including Puchyan Prairie (Wisconsin 

DNR 2012, in litt.). The Scuppernong 

Prairie SNA, Wilton Road, and Kettle 

Moraine Low Prairie SNA are managed 

primarily through fire and invasive 

species control. 

Furthermore, the Minnesota Zoo 

recently initiated a propagation research 

program for the Poweshiek skipperling 

and Dakota skipper to develop methods 

to propagate these and other species in 

the future. If this program is successful, 

a conservation benefit could be possible 

if the program could facilitate 

reintroduction and augmentation efforts 

into areas where the species has 


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declined or disappeared. Furthermore, 

this propagation effort may lead to 

increased knowledge of basic biology 

and life history of both species. 

To summarize, the conservation 

initiatives discussed above may 

ameliorate one or more stressors on 

populations of Dakota skipper and 

Poweshiek skipperling at a relatively 

small number of sites. Approximately 

12 Dakota skipper sites and 8 Poweshiek 

skipperling sites benefit from 

conservation easements; an additional 

12 Dakota skipper sites are owned by 

the Service and may benefit from 

implementation of Dakota skipper 

conservation guidelines; 2 sites in State 

parks are undergoing prairie restoration 

and management; approximately 5 

additional Dakota skipper sites and 4 

Poweshiek skipperling sites are 

managed to benefit prairie butterflies, 

such as rotational fire management. 

Since numerous sites have two or more 

stressors of moderate to high-level 

impacts to one or both species, all 

stressors are likely not completely 

ameliorated at many sites. Initiatives 

such as captive propagation and studies 

of the effects of various management 

techniques may be applied broadly and 

may be beneficial to each species as a 

whole—the timeframe for these benefits 

to be realized, however, will not be 

immediate. 

Factor B. Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

Although its biology could make the 

Dakota skipper sensitive to collection at 

some locations, the present level of 

scientific collection is minimal and 

recreational collecting is unlikely (Royer 

and Marrone 1992a, p. 27). Collection is 

not known to be a stressor for the 

Poweshiek skipperling (Royer and 

Marrone 1992b, p. 16). Collection is not 

currently a stressor to either species in 

Canada (COSEWIC 2003, p. 18). 

Scientific Collectors Permits are 

required in states where both species 

have legal protection, and permission is 

often required to collect specimens on 

protected areas. Furthermore, these 

species are not collected for commercial 

purposes; the drab coloration likely 

makes both species less desirable for 

collectors and the remoteness of 

occupied habitat and limited flight 

period would make recreational 

collections difficult (Borkin 2012, pers. 

comm.). Therefore, overutilization for 

commercial, recreational, scientific, or 

educational purposes is not currently a 

threat to Dakota skipper and Poweshiek 

skipperling. 

Handling stress during scientific 

study may be stressors to individuals of 

both species. Adverse effects on 

butterflies have been documented for a 

wide range of species (e.g., Benson and 

Emmel 1973, p. 329; Singer and 

Wedlake 1981, pp. 215–216; Lederhouse 

1982, pp. 381–382; Morton 1984, pp. 

56–57; Mallet et al. 1987, pp. 380–383). 

Although recreational collection is 

not a threat to these species at this time, 

due to the few populations, small 

population size, and restricted range, if 

any recreational collecting did occur in 

the future, even limited collection from 

the remaining small and isolated 

populations could have deleterious 

effects on these species’ reproductive 

and genetic viability. 

Factor C. Disease or Predation 

Diseases or parasites that are specific 

to the Dakota skipper or Poweshiek 

skipperling are not known, but some 

parasitism or predation likely occurs 

during each of the life stages. Disease 

and predation are part of the natural 

population dynamics of any insect, 

including the Dakota skipper and 

Poweshiek skipperling—without high 

rates of mortality before reproduction, 

populations would increase 

exponentially. The small amount of 

observations of predation and 

parasitism makes documenting those 

phenomenons difficult (Dana 2013, 

pers. comm.). Only a few studies have 

attempted to document parasitism and 

predation. For example, 10 of 130 eggs 

tagged for field observation in a 1994 

study of a Wisconsin Poweshiek 

skipperling population appeared to have 

suffered from predation or parasitism 

(Borkin 1995, p. 5); some were 

punctured and had the contents 

extracted, and others turned black and 

dried up. Dana (1991, pp. 19–21) 

documented some parasitism of Dakota 

skipper and Ottoe skipper (Hesperia 

ottoe) eggs and larvae by various wasp 

species and predation by various 

insects, such as ants, but escaping his 

observation would have been predation 

by birds and small mammals on these 

immature stages (Dana 2013, pers. 

comm.). 

Wolbachia, ubiquitous intercellular 

bacteria estimated to affect 20–70 

percent of all insect species, including 

many butterfly species, affects the 

reproductive ecology of its host 

(Kodandaramaiah 2011, pp. 343–350). It 

is uncertain if Wolbachia are affecting 

the Dakota skipper or Poweshiek 

skipperling. An infection of Wolbachia 

may reduce already small population 

sizes and increase the probability of 

extirpation (Nice et al. 2009, pp. 3137– 

3138), particularly if the population is 

infected with a novel strain (Runquist 

2013, pers. comm.). The Minnesota Zoo 

plans to conduct Wolbachia screening 

and strain identification of genomic 

DNA samples that the University of 

Michigan (at Dearborn) extracted from 

both species. The effects of predation by 

birds or insects on Dakota skipper or 

Poweshiek skipperling population 

dynamics are not known and may 

impact the species. 

McCabe (1981, p. 187), noted three 

kinds of predators to Dakota skippers, 

including Ambush bugs (Hemiptera: 

Phymata sp.), flower spiders (Aranaea: 

Misumena spp.), and orb weavers 

(various Araneldae). Flower spiders and 

ambush bugs are effective predators of 

nectar-feeding insects (McCabe 1981, 

pp. 187–188) and may cause mortality 

to some individuals, but it is difficult to 

quantify the population-level impacts of 

predators to either the Dakota skipper or 

Poweshiek skipperling. Dana 

documented predation on adult 

skippers by robber flies (Asilidae), 

which are common in upland prairie 

habitats, and noted the incidence of 

wing damage indicative of an 

unsuccessful attack by a bird or similar 

predator (Dana 1991, pp. 26–27; Dana 

2013, pers. comm.). Several incidences 

of predation by crab spiders and robber 

flies on both the Dakota skipper and 

Poweshiek skipperling have been 

documented in Canada, although it is 

not thought to be a common occurrence 

(Westwood 2013, pers. comm.). McCabe 

(1981) failed to observe bird or 

dragonfly predation; however these 

events are difficult to observe (Dana 

2013, pers. comm.). Orb weaver spiders 

appear to be successful predators of 

‘‘old, worn individuals’’ (McCabe 1981, 

p. 188), but bird and other animal 

predation on young and old adults 

likely occurs when the butterflies are 

roosting or torpid and unable to escape 

(Dana 1991, p. 27). 

Disease, parasitism, and predation are 

important parts of population dynamics 

of normal populations of insects, but 

may have an amplified effect on small 

populations. Furthermore, as we discuss 

in the possibility of unknown factors 

that may be affecting the species (in 

Factor E of this final rule), it is possible 

that a new virulent pathogen or 

parasitoid may have increased mortality 

above normal levels and may be causing 

the rapid decline in the Poweshiek 

skipperling and possibly also the Dakota 

skipper (Dana 2013, pers. comm.). 

Disease and parasitism are a serious 

hypothesis that may explain the rapid 

decline of the Poweshiek skipperling, 

and perhaps the Dakota skipper, and 

these factors, along with predation, are 

extremely difficult to observe. 

Therefore, we are unsure if either 

disease, parasitism, or predation are 


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significant stressors to the Dakota 

skipper or Poweshiek skipperling 

populations at this time, and we are not 

certain if these stressors will contribute 

to significant population-level impacts 

in the future. However, in the future, 

disease, parasitism, and predation may 

have an amplified effect on these small 

and isolated populations. 

Factor D. The Inadequacy of Existing 

Regulatory Mechanisms 

Existing regulatory mechanisms vary 

by location, but generally do not 

mitigate for the numerous stressors that 

the Dakota skipper and Poweshiek 

skipperling face. 

State Regulations 

The Dakota skipper is listed as 

endangered under Minnesota’s 

endangered species statute. Under the 

Minnesota statute, a person may not 

take, import, transport, or sell any 

portion of an endangered species of 

wild animal or plant, or sell or possess 

with intent to sell an article made with 

any part of . . . an endangered species 

of wild animal or plant’’ except as 

permitted by the Minnesota DNR 

(Minnesota Statutes 2012, 84.0895). The 

Poweshiek skipperling was listed as 

State-endangered in Minnesota, and the 

status of Dakota skipper was changed 

from threatened to endangered on 

August 19, 2013 (Minnesota DNR 2013). 

The Poweshiek skipperling is listed as 

threatened under State endangered 

species statutes in Iowa and Michigan 

and as endangered in Wisconsin. The 

Dakota skipper is listed as endangered 

under State endangered species statutes 

in Iowa. South Dakota has an 

endangered species act, but no 

invertebrates are currently listed. South 

Dakota put forth a proposal to add the 

Dakota skipper to the State endangered 

species act list, but it was not finalized. 

Although the Dakota skipper is not 

listed as threatened or endangered 

under South Dakota’s endangered 

species statute, the State natural 

heritage program considers the species 

to be imperiled because of rarity due to 

very restricted range and very few 

populations. North Dakota does not 

have a mechanism for conferring 

protection to threatened or endangered 

species at the State level. 

State endangered species statutes 

provide State natural resource or 

conservation agencies with the authority 

to regulate collection of individuals and 

related activities (for Poweshiek 

skipperling in Iowa, Michigan, and 

Wisconsin and Dakota skipper in 

Minnesota and Iowa), but we have no 

information to suggest that collection is 

a stressor that impacts populations of 

the species. With the exception of the 

regulation of some incidental take in 

Wisconsin and Minnesota, the statutory 

protections afforded by these State 

statutes may do little to protect or 

mitigate Poweshiek skipperling or 

Dakota skipper from non-collection 

threats. While some stressors may result 

in direct mortality of both species, such 

as ill-timed fires, most stressors to the 

species are indirect and State laws that 

regulate direct harm to the species do 

not address these factors. In Iowa, for 

example, Poweshiek skipperling 

populations are likely now extirpated 

due to habitat destruction and 

conversion and other undetermined 

stressors, despite the species’ presence 

on the State’s list of threatened species 

since 1994. In Wisconsin, where 

stressors from actions that may 

incidentally take Poweshiek 

skipperlings may be addressed in 

conservation plans, State endangered 

species protections do not protect the 

species from stochastic events and 

habitat fragmentation that are stressors 

to the State’s small and isolated 

populations. 

In North Dakota, the fundamental 

purpose of the North Dakota Trustlands 

(e.g., State school lands) management is 

to obtain a ‘‘fair market’’ return from the 

lands while maintaining or improving 

their condition and value (ND 

Department of Trustlands Web site 

http://www.land.nd.gov/surface/

About.aspx). Consequently, if such land 

does not produce income for the State, 

it may be subjected to deliberate change 

in management strategy or ownership 

(e.g., sale at auction). The major source 

of income on the North Dakota 

Trustlands is from grazing and 

agricultural leases, with additional 

revenue generated from rights-of-way, 

salt water disposal, and gravel and 

scoria mining (ND Department of 

Trustlands Web site http://

www.land.nd.gov/surface/About.aspx). 

At least two Dakota skipper sites are 

under North Dakota State School 

management and are managed as hay 

lands. 

Federal Regulations 

The U.S. Forest Service (Forest 

Service or USFS) has designated the 

Poweshiek skipperling and the Dakota 

skipper as sensitive species (a species 

identified by a Regional Forester for 

which population viability is a concern) 

in North Dakota (Forest Service 2011). 

The Forest Service’s objectives for 

sensitive species benefit Dakota skipper 

and Poweshiek skipperling where they 

occur (or could occur) on USFS lands; 

however, the majority of populations of 

both species do not occur within USFS 

lands. The Poweshiek skipperling has 

been documented at two sites on the 

Sheyenne National Grasslands; 

however, it has not been observed since 

2001 at one site and 1996 at the other. 

Therefore, these Forest Service 

objectives, although promising, have 

little ability to affect the rangewide 

status of the species. If Forest Service 

lands were to be occupied by either 

species in the future, these objectives 

may benefit the species at a local scale. 

Canadian Regulations 

Dakota skipper and Poweshiek 

skipperling are listed as threatened 

under Canada’s Species at Risk Act 

(SARA) (Environment Canada 2012. 

Species at Risk Act Public Registry. 

<http://www.registrelepsararegistry.gc.ca/sar/index/default_

e.cfm>. Accessed September 19, 2014). 

Under SARA, take of both species is 

prohibited on Canadian Federal lands, 

but the Poweshiek skipperling occurs 

only on non-Federal lands in Canada, 

and only four or five Dakota skipper 

sites are on Federal lands (Coalfields 

Community Pasture) in Canada. The 

Federal Cabinet may create an order 

extending SARA’s powers (e.g., to 

private lands) if a species is 

insufficiently protected by provincial 

laws; however, such action has not been 

taken for either of these species. In May 

2014, the COSEWIC status designation 

of Dakota skipper was changed from 

threatened to endangered (http://

www.cosewic.gc.ca/rpts/detailed_

species_assessments_e.html accessed 

September 19, 2014). The Dakota 

skipper is listed as threatened under the 

Manitoba Endangered Species Act, and 

it is, therefore, unlawful to kill, injure, 

possess, disturb, or interfere with the 

Dakota skipper; destroy, disturb, or 

interfere with its habitat; or damage, 

destroy, obstruct, or remove a natural 

resource on which the species depends 

for its life and propagation (Manitoba 

Endangered Species Act http://

www.gov.mb.ca/conservation/wildlife/

legislation/endang_act.html, accessed 

February 7, 2012). The Poweshiek 

skipperling was recently listed as 

endangered in Manitoba (http://

www.gov.mb.ca/conservation/wildlife/

sar/sarlist.html, accessed December 28, 

2012). There is no legal basis for 

protecting threatened or endangered 

invertebrates in Saskatchewan, but since 

both species are listed under SARA, the 

national government could step in to 

protect the species in the province if the 

province does not act to protect the 

species (Environment Canada. 2012. 

Species at Risk Act: A Guide. http://

www.sararegistry.gc.ca/approach/act/


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Guide_e.cfm, accessed February 7, 

2012). 

To summarize, some of the regulatory 

mechanisms discussed above are 

beneficial to populations of Dakota 

skipper and Poweshiek skipperling at a 

local scale; however, most do not 

ameliorate stressors except for harm to 

individuals in certain States. With the 

exception of the regulation of some 

incidental take in Wisconsin, 

Minnesota, and Canada, the statutory 

protections afforded by these statutes 

may do little to protect Poweshiek 

skipperling or Dakota skipper from noncollection stressors. 

Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence 

Habitat Fragmentation and Population 

Isolation 

As habitat specialists, habitat 

fragmentation has a strong negative 

effect on the distribution and abundance 

of the Dakota skipper and Poweshiek 

skipperling because both are dependent 

on remnant native tallgrass prairie or 

native mixed-grass prairie, and, in 

Michigan, Poweshiek skipperling 

depends on native prairie fens. Habitat 

fragmentation reduced once-extensive 

areas of these habitats to a collection of 

patches of varying quality and isolation. 

The probability of extinction within 

patches can be determined primarily by 

degradation of habitat quality, 

management techniques (e.g., haying, 

prescribed burns), and likelihood of 

stochastic events, such as wildfire or 

floods. 

Fragmentation of tallgrass prairie has 

degraded the genetic diversity of 

remaining Dakota skipper populations 

(Britten and Glasford 2002, pp. 371– 

372). What may have once been a single 

population of Dakota skippers spread 

across formerly extensive tallgrass and 

mixed-grass prairie (McCabe 1981, p. 

184) is now fragmented into about 171 

separate sites where the species is 

known to be or may still be present 

(sites with present (83) or unknown (88) 

status). The small genetic differences 

among seven Dakota skipper 

populations in the southern portion of 

the species’ range suggest that they were 

formerly connected (Britten and 

Glasford 2002, pp. 371–372). Each 

Dakota skipper population is now 

subject to genetic drift that may erode 

its genetic variability over time and 

possesses genetic qualities indicative of 

inbreeding (Britten and Glasford 2002, 

pp. 371–372). Inbreeding lowers the 

capacity of local populations to adapt to 

environmental changes and may 

magnify the effect of deleterious alleles 

(genes with undesirable effects on 

individuals or populations) (Nieminen 

et al. 2001, pp. 242–243). 

Preliminary results of genetic studies 

on the Poweshiek skipperling show that 

there appears to be limited levels of 

genetic diversity in the 32 tissue 

samples that were collected from the 

Scuppernong Prairie site in Wisconsin, 

7 samples from Manitoba, and 93 from 

6 Michigan populations in 2012 

(Saarinen 2013, pers. comm.). Of greater 

concern than loss of genetic diversity, 

however, may be demographics, 

specifically the limited number of 

populations and population sizes that 

may be too small to persist (Saarinen 

2013, pers. comm.) compounded by 

other stressors. 

Poweshiek skipperlings are not wide 

dispersers (Burke et al. 2011, p. 2279; 

Fitzsimmons 2012, pers. comm.); 

species experts have estimated 

maximum dispersal distance to be less 

than 1.6 km (1.0 mi) (Westwood 2012b, 

pers. comm; Dana 2012b, pers. comm.). 

Its mobility, however, has been ranked 

as less than that of Dakota skipper 

(Burke et al. 2011, p. 2279; Fitzsimmons 

2012, pers. comm.); therefore, a more 

conservative maximum dispersal 

distance may be more similar to that of 

the Dakota skipper (less than 1 km (0.6 

mi)). Most individuals may remain 

within a single habitat patch during 

their 5–7 day adult life span; therefore, 

local extinctions of the Poweshiek 

skipperling on isolated habitat 

fragments are likely permanent unless 

one or more populations located within 

1.0–1.6 km (0.6–1.0 mi) are large enough 

to produce immigrants to reestablish 

populations. Furthermore, 

fragmentation of tallgrass prairie began 

in about 1830, and at least 85 to 99 

percent of the original prairie is now 

gone across the species’ ranges (Samson 

and Knopf 1994, p. 419). As a result, 

Poweshiek skipperling and Dakota 

skipper populations are now scattered 

in fragments of this once-vast 

ecosystem. The Poweshiek skipperling 

may not move across barriers; for 

instance, in Manitoba, Poweshiek 

skipperlings have been observed 

avoiding dispersal over short distances, 

even to suitable habitat, if a barrier such 

as a road exists between suitable prairie 

habitat or nectar sources (Westwood et 

al. 2012, p.18). Repopulation of 

Poweshiek skipperling sites after 

extirpation has been observed (e.g., after 

a flood) (Saunders 1995, p. 15), but 

source populations need to be adjacent 

or very close. 

Similarly, adult Dakota skippers have 

a short (5- to 7-day) life span (Dana 

1991, p. 32) and an estimated maximum 

dispersal distance to be no greater than 

1 km (0.6 mi) between patches of prairie 

habitat separated by structurally similar 

habitats (Cochrane and Delphey 2002, 

pp. 6, 32). Therefore, Dakota skipper 

and Poweshiek skipperling habitat 

patches separated by more than 1 km 

(0.6 mi) are effectively isolated from one 

another (McCabe 1981, p. 190; Swengel 

1998). Extirpation of small, isolated 

populations may occur over many years 

in some cases, but may be inevitable 

where immigration from nearby 

populations is not possible (Hanski et 

al. 1996, p. 535). 

Because Dakota skipper and 

Poweshiek skipperling habitat is highly 

fragmented and because the species are 

subject to local extinction, their ability 

to disperse to reoccupy vacant habitat 

patches may be crucial for their longterm persistence. Patch isolation and 

decreased permeability of surrounding 

habitat acts as a dispersal barrier 

between patches, ultimately decreasing 

genetic diversity within the patch 

through genetic drift and inbreeding. If 

we assume isolation occurs when a 

patch is more than 1.6 km (1.0 mi) from 

another patch, then about 45 percent of 

Poweshiek skipperling locations with 

present or unknown status are 

effectively isolated, and would not be 

recolonized if extirpated (Service 2012 

unpubl. data; Service 2014, unpubl. 

data). Using a more conservative 

maximum dispersal of 1.0 km (0.6 mi), 

approximately 55 percent of Poweshiek 

skipperling locations with present or 

unknown status are effectively isolated. 

Isolation was a factor in loss of a site at 

Hartford Beach State Park, South 

Dakota, where the Poweshiek 

skipperling was extirpated due to 

habitat succession and exotic plant 

invasion (Skadsen 2009, p. 4; Skadsen 

2010, pers. comm.), but was located too 

far from a source population for natural 

recolonization to occur. Improved 

prairie management has since markedly 

improved habitat quality, but the 

species has not been detected since 

2006 at Hartford Beach State Park 

(Skadsen 2009, p. 4; Skadsen 2012, p. 4; 

Service 2014, unpubl. geodatabase). For 

Dakota skipper, if we use a maximum 

dispersal distance of 1 km (0.6 miles), 

approximately 63 percent of Dakota 

skipper sites with present or unknown 

status are effectively isolated (Service 

2014, unpubl. geodatabase). 

This simple analysis, however, 

probably underestimates the impacts of 

habitat fragmentation on the species. 

Populations of both species may only be 

near others that are too small to produce 

sufficient numbers of immigrants. This 

is true for the Poweshiek skipperling in 

Scuppernong Prairie in Wisconsin, for 

example, which is about 0.3 km (0.2 mi) 


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from the Wilton Road population; fewer 

than 100 individuals have been counted 

at this site each year, and the species 

was not observed in 2013 (See 

Population Distribution and Status). 

Numbers at Wilton Road are currently 

too small (fewer than 12 individuals 

counted each year) to produce sufficient 

numbers of emigrants to Scuppernong 

Prairie to reestablish a viable population 

in the event of the latter’s extirpation. 

There is no population of Poweshiek 

skipperlings near the Puchyan Prairie 

site (which is about 115 km (71 mi) from 

the nearest site in Wisconsin); 

additionally, only a few individuals 

have been observed at this site each 

year. In North Dakota, Orwig (1997, p. 

3) found that a 6-ha (15-ac) patch of 

Poweshiek skipperling habitat at 

Hartleben Prairie was connected by 

grassland to another Poweshiek 

skipperling population, but neither was 

considered a robust population at the 

time and the species was not observed 

at either location in 2013. Only 2 of the 

9 Poweshiek skipperling sites with 

present status in Michigan are located 

within 1.6 km (1 mi) of another site; the 

rest are completely isolated from other 

populations. Furthermore, most of these 

populations consist of few individuals 

(see Population Distribution and 

Status). Poweshiek skipperlings at Little 

Goose Lake Fen, for example, are 

separated from other populations by at 

least 8 km (5 mi)—too far for immigrants 

to repopulate the site. Furthermore, 

Little Goose Lake Fen may contain too 

few Poweshiek skipperlings (Michigan 

Natural Features Inventory 2011, 

unpubl. data; Cuthrell 2013, pers. 

comm.) to generate sufficient numbers 

of immigrants. In addition, poor habitat 

quality negatively influences the 

number and quality of emigrants 

(Thomas et al. 2001, p. 1795; Matter et 

al. 2009, p. 1467). Isolation is not likely 

alleviated by connections to low-quality 

habitats that are not capable of 

producing emigrants at the numbers or 

frequency sufficient to reliably 

repopulate nearby patches. 

Even with proper prairie management 

at individual sites, extreme weather 

patterns or severe weather events may 

significantly impact Poweshiek 

skipperling and Dakota skipper 

populations, because they can occur 

across a large geographic area. These 

events include extremely harsh winters, 

late hard frosts following a spring thaw, 

severe storms, flooding, fire, or cool 

damp conditions. Habitats isolated as a 

result of fragmentation will not be 

recolonized naturally after local 

extirpations, as described above. Dakota 

skipper and Poweshiek skipperling 

numbers may decline due to the 

extirpation of isolated local populations 

where recolonization is no longer 

possible, even without further habitat 

destruction (Schweitzer 1989, 

unpaginated). The likelihood of 

population extirpation may be directly 

related to the size of habitat fragments. 

For example, in systematic surveys on 

Minnesota prairies, Swengel and 

Swengel (1997, pp. 134–137; 1999, p. 

284) found no Dakota skippers on the 

smallest remnants (less than 20 ha (49 

ac)), and significantly lower abundance 

on intermediate size (30–130 ha (74–321 

ac)) than on larger tracts (greater than 

140 ha (346 ac)). These differences were 

unrelated to vegetation characteristics; 

habitat area did not correlate 

significantly with vegetation type, 

quality, or topographic diversity 

(Swengel and Swengel 1999, p. 284). 

We assessed the stressor of small size 

and isolation of habitat for 163 Dakota 

skipper sites and 54 Poweshiek 

skipperling sites with present or 

unknown status (Service 2012 unpubl. 

data; Service 2014, unpubl. data). We 

considered small size and isolation of 

habitat to be a stressor with a low-level 

impact on populations at sites that 

contain more than 140 ha (346 ac) of 

native prairie or the species’ habitat 

onsite is located less than 1 km (0.6 mi) 

from habitat occupied by the species on 

another site. If the sum of native prairie 

on the site under review plus that on the 

nearby site(s) is less than 140 ha (346 

ac), then this stressor was considered to 

have a moderate or high impact on 

populations. We considered small size 

and isolation of habitat to be a stressor 

with moderate impacts on populations 

at sites where the species’ habitat is 

greater than 1 km (0.6 mi) from any 

other area where the species is present, 

but contains more than 30 ha (74 ac) of 

habitat for the species; or where the 

species’ habitat is less than 1 km (0.6 

mi) from occupied Dakota skipper and 

Poweshiek skipperling habitat on 

another site, but the sum of native 

prairie on the site under review plus 

that on the nearby site(s) is less than 140 

ha (346 ac) and greater than 30 ha (74 

ac). Sites that contain a small area of 

Dakota skipper and Poweshiek 

skipperling habitat—no more than 30 ha 

(74 ac)—and that are not within the 1- 

km (0.6-mi) estimated maximum 

dispersal distance of occupied Dakota 

skipper habitat are considered to have a 

stressor of high magnitude to those 

populations due to a combination of 

their small size and isolation. 

Although we were unsure of the size 

of many sites in Canada, most sites were 

separated by more than 1 km (0.6 mi). 

Dakota skipper sites in central Manitoba 

are generally greater than 158 ac (64 ha), 

but all of the sites are separated by more 

than 1 km (0.6 mi), and many sites are 

separated by many kilometers 

(Westwood 2013 pers. comm.). 

Therefore, about 25 of the sites 

evaluated in Canada were thought to 

have at least a moderate level of stressor 

from size and isolation. The Canada 

sites where Dakota skippers are 

considered to be present are 

approximately 200 km (125 mi) from the 

nearest North Dakota site, and the 

Manitoba site is 166 km (103 mi) from 

the nearest Poweshiek skipperling site 

in Minnesota. 

Dakota skipper populations on about 

31 percent of the evaluated sites (50 of 

163 sites) face a high level of impact due 

to a combination of size and isolation 

(Service 2012 unpubl. data, 2014 

unpubl. data). Approximately 31 

percent of evaluated sites (50 sites) face 

a moderate level of impact to 

populations due to small size and 

isolation. About 39 percent of Dakota 

skipper sites (63 of the 163 evaluated 

sites) in the United States are either 

sufficiently large (greater than 130 ha 

(346 ac)) or are close enough to other 

Dakota skipper populations that small 

size and isolation is not a stressor. 

Similarly, the stressor of small size and 

isolation has a high level of impact on 

Poweshiek skipperling populations on 

about 39 percent of rated sites (25 of 54 

sites), on 22 sites (41 percent) the 

stressor is considered to have a 

moderate level of impact to populations, 

and on 20 percent (11 of the 54 

evaluated sites) of the sites, we do not 

consider a small size and isolation to be 

a stressor. In a separate analysis strictly 

looking at distances between Poweshiek 

skipperling sites where the species is 

present, we found that only 4 sites are 

within 1 km (0.6 mi) of another site 

where the species is present (Service 

2014, unpubl geodatabase). 

In summary, small, isolated 

populations face a current and ongoing 

stressor of moderate to high severity to 

both the Dakota skipper and Poweshiek 

skipperling. The stressor has a high 

impact to populations when isolation is 

combined with small habitat fragments 

or small populations; for example, 

where the population is too small to 

supplement nearby populations without 

adverse genetic consequences to the 

source population. Isolated populations 

occur throughout both species’ entire 

ranges; only 4 of the 12 Poweshiek sites 

with present status are within the 

estimated maximum dispersal distance 

from one another as are about 40 

percent (64–69 of 171 sites) of Dakota 

skipper sites with present or unknown 

occupancy. The small populations are 


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subject to erosion of genetic variability 

leading to inbreeding, which lowers the 

ability of the species to adapt to 

environmental change. Small 

populations occur rangewide for both 

species; for example, surveyors have 

counted fewer than 100 individuals in 

all but 4 Poweshiek skipperling sites in 

2011, all but one site surveyed in 2012, 

and all sites surveyed in 2013. 

Climate Change 

Our analyses under the Act include 

consideration of the likely effects of 

ongoing and projected changes in 

climate. The terms ‘‘climate’’ and 

‘‘climate change’’ are defined by the 

Intergovernmental Panel on Climate 

Change (IPCC). ‘‘Climate’’ refers to the 

mean and variability of different types 

of weather conditions over time, with 30 

years being a typical period for such 

measurements, although shorter or 

longer periods also may be used (IPCC 

2013, p. 1450). The term ‘‘climate 

change’’ thus refers to a change in the 

mean or variability of one or more 

measures of climate (e.g., temperature or 

precipitation) that persists for an 

extended period, typically decades or 

longer, whether the change is due to 

natural variability, human activity, or 

both (IPCC 2013, p. 1450). Various types 

of changes in climate can have direct or 

indirect effects on species. These effects 

may be positive, neutral, or negative and 

they may change over time, depending 

on the species and other relevant 

considerations, such as the effects of 

interactions of climate with other 

variables (e.g., habitat fragmentation) 

(IPCC 2007, pp. 8–14, 18–19). We use 

our expert judgment and appropriate 

analytical approaches to weigh relevant 

information, including uncertainty, in 

our consideration of various aspects of 

climate change. 

As is the case with all stressors that 

we assess, even if we conclude that a 

species is currently affected or is likely 

to be affected in a negative way by one 

or more climate-related impacts, it does 

not necessarily follow that the species 

meets the definition of an ‘‘endangered 

species’’ or a ‘‘threatened species’’ 

under the Act. If a species is listed as 

endangered or threatened, knowledge 

regarding the vulnerability of the 

species to, and known or anticipated 

impacts from, climate-associated 

changes in environmental conditions 

can be used to help devise appropriate 

strategies for its recovery. 

Global climate change, with 

projections of increased variability in 

weather patterns and greater frequency 

of severe weather events, as well as 

warmer average temperatures, would 

affect remnant prairie habitats and 

prairie fen habitats and may be a 

stressor that has significant impacts on 

prairie butterflies such as Dakota 

skippers and Poweshiek skipperling 

(Royer and Marrone 1992b, p. 12; Royer 

and Marrone 1992a, pp. 22–23; Swengel 

et al. 2011, p. 336; Landis et al. 2012, 

p. 140). For example, climatic factors, 

particularly precipitation and 

evaporation, play an important role in 

defining suitable Dakota skipper habitat 

(McCabe 1981, pp. 189–192). Larval 

Dakota skipper have ‘‘hydrofuge glands’’ 

that suggest an historical or present 

need of the species for protection from 

flooding (McCabe 1981, p. 181). Royer et 

al. (2008, p. 2) hypothesize that 

temperature and relative humidity at or 

near the soil surface may be important 

factors dictating larval survival, 

particularly since early stages live in a 

silken nest within a few centimeters (2– 

3) (0.8–1.2 in) of the soil surface during 

most of the summer (McCabe 1981, pp. 

180–181, 189; Dana 1991, p. 16). 

Furthermore, both species and their 

habitats may experience the effects of 

gradual shifts in plant communities and 

an increase in catastrophic events (such 

as severe storms, flooding, and fire) due 

to climate change, which are 

exacerbated by habitat fragmentation. 

Isolated populations, specifically, 

Dakota skipper populations and 

Poweshiek skipperling populations that 

are separated by more than about 1 km 

(0.6 miles), are unlikely to recover from 

local catastrophes unless sufficient 

numbers are successfully reintroduced, 

for instance, through artificial 

propagation efforts. 

Documentation of climate-related 

changes that have already occurred 

throughout the range of the Dakota 

skipper and Poweshiek skipperling 

(Johnson et al. 2005, pp. 863–871) and 

predictions of changes in annual 

temperature and precipitation in the 

Midwest region of the United States, 

such as Minnesota prairies 

(Galatowitsch et al. 2009, pp. 2017), 

Michigan fens (Landis et al. 2012, p. 

140), South Dakota (Cochrane and 

Moran 2011, entire), and throughout 

North America (IPCC 2007, p. 9) 

indicate that increased severity and 

frequency of droughts, floods, fires, and 

other climate-related changes will 

continue in the future. Recent studies 

have linked climate change to observed 

or predicted changes in distribution or 

population size of insects, particularly 

Lepidoptera (Wilson and Maclean 2011, 

p. 262). Native remnant prairies have 

been reduced by 85 to 99.9 percent 

across the range of both species (Samson 

and Knof 1994, p. 419)—this fact, 

coupled with the low dispersal ability of 

both species, makes it unlikely that 

populations may expand to new areas, 

for example, in a northward direction, 

to adapt to changing climate. Climate 

change is a stressor that has the 

potential to have severe impacts on the 

species; however, at this time our 

knowledge of how these impacts may 

play out is limited. All of the sites 

within the range of both species are in 

an area that will experience the effects 

of climate change, but how those effects 

will be manifested is uncertain. 

Prairie Plant Harvesting 

A potential, future stressor to the 

Dakota skipper and Poweshiek 

skipperling is collection of purple 

coneflower (also known as black samson 

echinacea), a predominate nectar source 

for both species, for the commercial 

herbal remedy market (Skadsen 1997, p. 

30). Biologists surveying skipper 

habitats have not reported signs of plant 

collecting, but illegal or unregulated 

harvest could become a problem in 

Dakota skipper and Poweshiek 

skipperling habitats due to economic 

demand (Skadsen 1997, p. 30). 

Currently, prairie plant harvesting is not 

considered a threat that impacts the 

species; however, this situation may 

change if the demand for echinacea 

increases. 

Management for Invasive Species and 

Succession 

Native prairie and native prairie fens 

must be managed to prevent the indirect 

effects of invasive species and 

succession (processes of change in 

species structure to an ecological 

community over time; secondary 

succession is a disruption to succession 

that occurs due to an event such as fire) 

to Dakota skippers and Poweshiek 

skipperlings. If succession progresses 

too far, established shrubs or trees must 

be removed in a way that avoids or 

minimizes damage to the native prairie. 

When succession is well advanced, 

managers must use intensive methods, 

such as fire management, to restore 

prairie plant communities. If not done 

carefully, these actions may themselves 

harm local populations of the butterflies 

(for example, see Factor A. The Present 

or Threatened Destruction, 

Modification, or Curtailment of Its 

Habitat or Range). For example, once 

smooth brome has invaded Poweshiek 

skipperling or Dakota skipper habitat, it 

is challenging to eradicate it while 

minimizing harm to the butterflies. 

Willson and Stubbendiecks (2000, p. 36) 

recommended burning prairie habitats, 

annually in some cases, to control 

smooth brome at the stage when the 

lateral shoots are elongating. 


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In southwestern Minnesota and in 

other parts of Dakota skipper’s range, 

the optimum time to burn to control 

smooth brome may occur during the 

time that the adult butterflies are active. 

Cutting or grazing to remove smooth 

brome may have less intensive effects 

on Poweshiek skipperling and Dakota 

skipper larvae and could be used as an 

alternative to fire, although these 

techniques also pose a risk to both 

species if carried out annually at 

isolated sites. Puchyan Prairie is another 

example of a small and isolated 

population that is susceptible to 

invasive species control efforts, if they 

are not conducted properly (Swengel 

and Swengel 2012, p. 6), although the 

Wisconsin DNR proposed control efforts 

that may improve habitat by removing 

reed canary grass, Canada thistle, and 

glossy buckthorn (Wisconsin DNR 2012 

in litt.; Carnes 2012, in litt.). 

If not appropriately managed with 

fire, grazing, or haying, Poweshiek 

skipperling and Dakota skipper habitat 

is degraded due to reduced diversity of 

native-prairie plants and eventually 

succeeds to shrubby or forested habitats 

that are not suitable for either species. 

At Hartford Beach State Park in South 

Dakota, for example, the Poweshiek 

skipperling was extirpated (Skadsen 

2009, p. 4) after lack of management led 

to invasion by smooth sumac (Rhus 

glabra) and quaking aspen (Populus 

tremuloides) (Skadsen 2006a, p. 5). Lack 

of management may also increase the 

likelihood of invasion of exotic coolseason grasses, such as Kentucky 

bluegrass and smooth brome (Mueller 

2013, pers. comm.), which do not grow 

when Dakota skipper and Poweshiek 

skipperling larvae are feeding; thus a 

prevalence of these grasses reduces food 

availability for the larvae. 

As with invasive species, actions 

intended to reverse secondary 

succession may be intensive and can 

themselves affect Poweshiek skipperling 

and Dakota skipper populations. For 

example, Poweshiek skipperling 

populations failed to recover after 

prescribed burns were carried out at 

Kettle Moraine Low Prairie SNA after it 

had become overgrown (Borkin 2011, in 

litt.). 

Although carefully targeted herbicide 

treatments result in beneficial control of 

undesired plants, broadcast chemical 

control of exotic plants such as aerial 

spraying of leafy spurge and application 

of broad-spectrum herbicides to control 

weeds in pastures also eliminates native 

forbs that are important nectar sources 

for both species (Royer and Marrone 

1992a, pp. 10, 16, 28, 29, 33, 1992b, p. 

17, Orwig 1997, p. 7). For example, 

invasion of native prairie by exotic 

species, primarily leafy spurge and 

Kentucky bluegrass, as well as chemical 

control of exotic species, are 

documented stressors to Dakota 

skippers at about 12 sites in North 

Dakota (Royer and Royer 2012b, pp. 15– 

16, 22–23). In repeated surveys, Royer 

and Marrone (1992a, p. 33) observed a 

correlation between the disappearance 

of the Dakota skipper and the advent of 

chemical weed control methods in 

North Dakota, including the Sheyenne 

National Grasslands. Royer and Marrone 

(1992b, p. 17) cited the combination of 

drought and grasshopper control 

programs along the Red River Valley as 

having serious impacts on the 

Poweshiek skipperling. Dana (1997, p. 

5) concluded that herbicide use for 

weed and brush control on private lands 

is the principal stressor to the Hole-inthe-Mountain complex in Minnesota, 

where both butterfly species have been 

documented. 

Furthermore, herbicide or pesticide 

use in concert with other management 

types may amplify other stressors to the 

butterflies. Skadsen (2006b, p. 11), for 

example, documented the likely 

extirpation of the Poweshiek skipperling 

at Knapp Ranch in South Dakota after a 

July 2006 application of broadleaf 

herbicide associated with heavy grazing. 

The degree and immediacy of the 

impact posed by broadcast application 

of herbicides or pesticides is not 

precisely understood, but may be mostly 

tied to the use of herbicides to control 

invasive species on rangelands. If broad 

applications of herbicides are used in 

ways that remove plants from 

rangelands that are important for 

Poweshiek skipperling or Dakota 

skipper, then this is a potential stressor 

on all privately owned sites where 

broadcast applications may occur. 

Indiscriminant use of insecticides for 

pest control on rangeland, adjacent 

cropland, or forests is a stressor to 

populations of Poweshiek skipperling 

and Dakota skipper. Insecticides used in 

agriculture, urban gardens, and forests 

are a suspected cause of Colony 

Collapse Disorder in bees by reducing 

resistance to parasites and pathogens 

and may have similar effects on other 

insects (Beyers 2012, p. 1). Neonicotinyl 

pesticides, such as the imidacloprid 

compound, for example, are a 

commonly used seed dressing that 

spreads to nectar and pollen of 

flowering crops (Whitehorn 2012, p. 1). 

The use of neonicotinoids on 

agricultural crops has dramatically 

increased in the last ten years and they 

are now the most widely used group of 

insecticides in the world (Jeschke et al. 

2011, pp. 2897–2898; Main et al. 2014, 

p. 2; Goulson 2013, pp. 1–2). 

Neonicotinoids persist in the 

environment (Goulson 2013, p. 1) and 

are thought to accumulate in the soil 

from repeated applications over time 

(Hopwood et al. 2013, p. 4). Insects can 

be exposed through multiple routes— 

neonicotinoids are used in seed 

dressings, foliar spray, soil irrigation 

water, soil drench, granular in pastures, 

tree injections, and topical applications 

to pets. 

In the United States, six 

neonicotinoids are approved for use— 

imidacloprid, thiamethoxam, 

clothianidin, dinotefuran, thiacloprid, 

and acetamiprid (EPA 2014 Web site)— 

and it is estimated that more than 3.5 

million pounds (56 million ounces) of 

neonicotinoids were applied to nearly 

127 million acres (51 million hectares) 

of agricultural crops each year from 

2009 to 2011. The presence and 

concentrations of neonicotinoids at 

Dakota skipper and Poweshiek 

skipperling sites or nearby agricultural 

fields that use neonicotinoid seed 

treatments or other such treatments has 

not been assessed, however, in general, 

nearly 100 percent of corn is known to 

be treated, and about 75 percent of 

soybean seeds are known to be treated 

with neonicotinoids, for example. 

Similarly, soybean aphid spraying 

occurs during the adult flight period, is 

widespread, and applied aerially—this 

spray can drift to nearby Dakota skipper 

or Poweshiek skipperling habitat. The 

presence and concentrations of 

insecticides at Dakota skipper and 

Poweshiek skipperling sites or nearby 

agricultural fields that utilize soybean 

aphid spraying has not been assessed. 

The Minnesota Zoo has proposed a 

study to investigate the levels of 

neonicotinoids, aphid pesticides, and 

other insecticides that may be present at 

several skipper sites in Minnesota and 

South Dakota. 

The spread of nonnative gypsy moths 

(Lymantria dispar dispar) has increased 

efforts to control this damaging species 

and may also be a stressor, especially in 

the range of Poweshiek skipperling. 

Insecticides used in the gypsy moth 

suppression programs typically include 

Foray, a formulation of the bacterial 

insecticide Bacillus thuringiensis 

kurstakii (Btk), or Gypchek, a viral 

insecticide specific to gypsy moth 

caterpillars. Btk is known to be lethal to 

butterfly larvae (e.g., Karner blue 

butterfly) (Carnes 2011, p. 1). In 

Wisconsin, the gypsy moth suppression 

program is managed under State Statute 

26.30 and Natural Resources Board Rule 

number 47, and Gypchek is used when 

endangered or threatened moths or 

butterflies are present (Wisconsin DNR, 

http://dnr.wi.gov/topic/ForestHealth/


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GypsyMothPesticides.html, accessed 

May 24, 2012). 

Herbicide and pesticide use was 

assessed at 15 present and unknown 

Dakota skipper sites and 9 Poweshiek 

skipperling sites occupied with present 

or unknown occupancy where we had 

sufficient information to evaluate the 

stressor (Service 2012 unpubl.; 2014, 

unpubl. data). We considered the level 

of impact to populations posed by 

herbicide and pesticide use to be low if 

the site is only spot sprayed with 

herbicides or pesticides when and 

where necessary (Smart et al. 2011, p. 

182) and their use is not expected to 

change in the future. The level of 

stressor was considered to be moderate 

if the use of herbicides is likely to 

increase at a site (e.g., in response to 

new or expanding invasive species), but 

Dakota skipper and Poweshiek 

skipperling habitat is unlikely to be 

exposed to broadcast applications. The 

level of impact to populations posed by 

herbicide and pesticide use was 

considered to be high at sites where 

herbicides are likely to be broadcast 

over the entire site at least once every 

4 years, or herbicide use has 

significantly reduced forb or nectar 

plant density and diversity or is likely 

to in the future. The level of impact to 

populations posed by herbicide and 

pesticide use was high at 5 of the 16 

assessed Dakota skipper sites (2 in 

North Dakota and 3 in South Dakota) 

and moderate at 2 sites—1 in North 

Dakota and 1 in South Dakota. The level 

of impact to populations posed by 

herbicide and pesticide use was 

considered to be high at 3 of the 9 

assessed Poweshiek skipperling sites 

(all 3 in South Dakota), and 1 site in 

North Dakota had a moderate level of 

impact to populations. 

In summary, some efforts to manage 

woody encroachment and invasive 

species, such as herbicide use, can be a 

stressor to both Dakota skipper and 

Poweshiek skipperling populations. 

Invasive species management is a 

current and ongoing stressor of low to 

high impact to populations, depending 

on the intensity and extent of the use, 

types of techniques, and the 

compounding effects that may occur 

from varying management. Medium- to 

high-level impacts of herbicide or 

pesticide use to Dakota skipper and 

Poweshiek skipperling populations have 

been documented in North and South 

Dakota. This stressor has a high impact 

to populations when it is combined 

with other stressors, such as 

management, that reduces or eliminates 

nectar food sources, or small habitat 

fragments that are isolated from other 

source populations that may replenish 

individuals killed by pesticides. 

Herbicide and pesticide use may have 

direct or indirect effects on Dakota 

skipper and Poweshiek skipperling. 

Although such activities occur, there is 

no evidence that these activities alone 

have significant impacts on either 

species, since their effects are often 

localized. However, these factors may 

have a cumulative effect on the Dakota 

skipper and Poweshiek skipperling 

when added to habitat curtailment and 

destruction because dramatic 

population declines have occurred in 

both species (discussed in Factor A). 

Invasive species and woody vegetation 

management helps to maintain prairie 

habitats and can also be beneficial to 

populations of both species, for 

example, when concentrated on affected 

areas through spot spraying. 

Pharmaceuticals 

The effect of pharmaceutical residues 

in the environment on nontarget 

animals is an emerging concern (Lange 

et al. 2009). Ivermectin, a widely used 

and persistent veterinary 

pharmaceutical used to treat cattle, is a 

chemical of emerging concern to the 

Dakota skipper and Poweshiek 

skipperling. Ivermectin is an 

anthelmintic (drugs that are used to 

treat infections with parasitic worms) 

that is spread to prairie environments 

via the dung of grazing cattle (Lange et 

al. 2009, p. 2238). Lange et al. (2009, pp. 

2234, 2238) found that skipper 

butterflies are particularly vulnerable to 

ivermectin, due to their low dispersive 

capacities and habitat preferences for 

soil. The extirpation of the Dakota 

skipper in at least one South Dakota site 

(Sica Hollow West) is possibly due to 

ivermectin that has leached into the 

environment (Skadsen 2010, pers. 

comm.). 

Pharmaceutical use is a stressor that 

has the potential to have high-level 

impacts on populations of the Dakota 

skipper and Poweshiek skipperling; 

however, at this time our knowledge of 

these impacts is limited. Sites within 

the range of both species could 

experience the effects of 

pharmaceuticals. Sites that experience 

grazing, however, are particularly 

vulnerable to ivermectin use; these sites 

are primarily in South Dakota, North 

Dakota, and Minnesota. The use of 

pharmaceuticals such as ivermectin may 

have a cumulative effect on the Dakota 

skipper and Poweshiek skipperling 

when added to habitat curtailment or 

destruction, because habitat destruction 

leads to population declines in 

populations of both species (discussed 

in Factor A). 

Unknown Stressors Causing Population 

Declines 

The sharp and broad declines of 

Poweshiek skipperling documented in 

Iowa, Minnesota, North Dakota, and 

South Dakota are indicative of a 

response to one or more stressors that 

have yet to be ascertained. These 

unknown factors may consist of a 

combination of one or more of the 

stressors described throughout Factors 

A, C, and E of this final rule, or may be 

something that has not yet been 

identified. These declines are 

reminiscent of the widely publicized 

decline of honey bees (Apis mellifera) in 

that they seem sudden and mysterious 

(Spivak et al. 2011, p. 34). One 

hypothesis to explain the rapid decline 

of the Poweshiek skipperling, and 

possibly the Dakota skipper, is that a 

newly virulent pathogen or a new 

parasitoid has increased mortality above 

normal levels (Dana 2013, pers. comm.). 

One or more unidentified stressors 

have strongly impacted Poweshiek 

skipperling populations in the western 

portion of its range, which contains 

more than 80 percent of the species’ site 

records. Unknown stressors may be the 

current factor with the most significant 

impacts to Poweshiek skipperling in 

Minnesota, North Dakota, and South 

Dakota, where populations experienced 

a sudden decline to undetectable 

numbers after about 2003. Until about 

2003, Poweshiek skipperling was 

regarded as the most frequently and 

reliably encountered prairie-obligate 

skipper in Minnesota, which contains 

nearly 50 percent of all known 

Poweshiek skipperling locations. 

Numbers and distribution dropped 

dramatically in subsequent years, 

however, and the species has not been 

seen in Minnesota since 2007, with the 

exception of 2 individuals observed at 

one location in 2013 (Weber 2014, in 

litt.; Dana 2014, pers. comm.). Similar 

recent dramatic declines were observed 

in North Dakota, South Dakota, and 

Iowa (See Background of this rule). 

Recent declines of Dakota skippers 

indicate that this species may also be 

impacted by unknown stressors. The 

Dakota skipper was last detected at one 

site in Iowa in 1992. Only one 

individual was detected in Minnesota 

during 2012 surveys, which included 18 

sites with previous records; surveys for 

undiscovered populations were also 

carried out on 23 prairie remnants 

without previous records for the 

species. Only six individual Dakota 

skippers were detected at one site in 

Minnesota during 2013 surveys, which 

included 15 sites with previous records 

and 12 prairie remnants without 


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previous records for the species (Service 

2014, unpubl. geodatabase.). Based on 

similar conditions in other parts of the 

species’ range, similar trends are 

anticipated outside of Minnesota. 

Indications of recent declining trends 

have been observed in South Dakota and 

North Dakota. In South Dakota, for 

example, the proportion of positive 

surveys at known sites has fluctuated 

over time; however, the 2012 and 2013 

surveys had the lowest positive 

detection rate (38 percent and 32 

percent, respectively) for the last 15 

years (since 1996)—much less than 

comparable survey years in South 

Dakota (for years with more than 20 

surveys). The Dakota skipper was 

detected at 12 of the 23 sites surveyed 

during 2012 in North Dakota (and 2 

additional sites with no previous Dakota 

skipper records); average encounter 

frequencies observed across the State in 

2012 (9.4 encounters per hour), 

however, were about half of those 

observed during the 1996–1997 Statewide surveys (ND State average = 17.4 

encounters per hour). The Dakota 

skipper was not detected at the three 

sites that were surveyed in 2013 in 

North Dakota with previous records of 

the species. Recent survey results and 

similar life histories suggest that the 

Dakota skipper can be reasonably 

compared to the Poweshiek skipperling 

in their potential rate of decline—that 

is, it is reasonable to assume that Dakota 

skipper may be vulnerable to the same 

unidentified factors that have caused 

dramatic declines in the Poweshiek 

skipperling, with a slight delay in 

timing. 

In summary, the results of extensive 

surveys in the western portion of the 

Poweshiek skipperling’s range have 

documented the species’ response to 

unknown factors and indicate that they 

are a current stressor of high severity. 

Although to date the Dakota skipper has 

not experienced such dramatic declines 

as the Poweshiek skipperling, similar 

unknown stressors on Dakota skipper 

populations likely have affected the 

species in Minnesota and Iowa, where 

recent surveys indicate that the species 

may be largely absent or at undetectable 

levels. 

Summary of Factor E 

Based on our analysis of the best 

available information, we have 

identified several natural and manmade 

factors affecting the continued existence 

of the Dakota skipper and Poweshiek 

skipperling. Effects of small population 

size, population isolation, and loss of 

genetic diversity are likely stressors that 

have significant impacts on both 

species. Environmental effects resulting 

from climatic change, including 

increased flooding and drought, are 

expected to become severe in the future 

and result in additional habitat losses; 

however, we have limited information 

on how this stressor may affect either 

species. Possibly the stressor with the 

most significant impacts to the 

Poweshiek skipperling are one or more 

unknown factors that have led to 

widespread and sharp population 

declines in the western portion of the 

species’ range. These unknown stressors 

may also be the cause of the recent 

declines observed in Dakota skipper 

populations over much of its range. 

Anthropogenic factors such as 

insecticide, herbicide, and pesticide use 

are also stressors to both species, and 

unregulated prairie plant harvest has the 

potential to become a stressor in the 

future (See Factor E). Collectively, these 

stressors have operated in the past, are 

impacting both species now, and will 

continue to impact the Dakota skipper 

and Poweshiek skipperling in the 

future. 

Conservation Efforts To Reduce Other 

Natural or Manmade Factors Affecting 

Its Continued Existence 

Several of the conservation activities 

discussed under Factor A. in this rule 

may address some factors discussed 

under Factor E, for example, life-history 

studies of both species, studies to 

examine the effects of various 

management strategies on the species 

and its habitat, and habitat restoration 

techniques such as controlled burns on 

sites divided into several management 

units. 

The Minnesota Zoo has initiated a 

new program to research Poweshiek 

skipperling and Dakota skipper 

propagation. If this program is 

successful, it could facilitate 

reintroduction and augmentation into 

areas where the species has declined or 

disappeared, to bolster the small genetic 

pool and small numbers. In 2012, 

researchers at the Minnesota Zoo and 

the University of Michigan initiated a 

genetics study of Dakota skipper and 

Poweshiek skipperling using specimens 

at some of the few sites where either 

species was observed in 2012, 

specifically a few sites in Michigan, 

Wisconsin, and Manitoba for the 

Poweshiek skipperling and sites in 

North Dakota, South Dakota, and 

Manitoba for Dakota skipper. Too few 

(one adult male) Dakota skipper were 

observed in Minnesota to obtain 

samples from that State in 2012. 

Similarly, only six individuals were 

observed at one Minnesota site in 2013. 

The genetics studies will help inform 

captive propagation and reintroduction 

efforts, which may help alleviate 

stressors associated with small and 

isolated populations. 

In 2011, researchers collected 32 adult 

Dakota skippers from a combination of 

4 sites in South Dakota and translocated 

them to Pickerel Lake State Park, where 

the species was last detected in 2008 

(Skadsen 2011, pp. 7–9). The phenology 

of the adult flight period and purple 

coneflower blooms did not coincide, 

and no Dakota skippers were observed 

at the release site during subsequent 

visits in 2011 or 2012 (Skadsen 2011, 

pp. 8–9, Skadsen 2012, p. 4). 

Researchers and managers continue to 

develop prairie restoration and 

management goals for this and the 

Hartford Beach State Park site in South 

Dakota (Skadsen 2011, p. 9; Skadsen 

2012b, p. 7). 

The Minnesota Zoo has also begun a 

study to investigate the levels of 

neonicotinoids, aphid pesticides, and 

other insecticides present at several 

skipper sites in Minnesota and at least 

one site in South Dakota. 

We are unaware of any conservation 

efforts that directly address the impacts 

of climate change to Dakota skippers or 

Poweshiek skipperlings. We are 

unaware of any conservation efforts that 

address the possible effects of 

pharmaceuticals on the Poweshiek 

skipperling and Dakota skipper. 

Cumulative Effects From Factors A 

Through E 

Many of the stressors described in this 

final rule may cumulatively or 

synergistically impact the Dakota 

skipper and Poweshiek skipperling 

beyond the scope of each individual 

stressor. For example, improper grazing 

management alone may only affect 

portions of Dakota skipper or Poweshiek 

skipperling habitat; however, improper 

grazing combined with invasive plants, 

herbicide use, and drought may 

collectively result in substantial habitat 

loss, degradation, or fragmentation 

across large portions of the species’ 

ranges. In turn, climate change may 

exacerbate those effects, further 

diminishing habitat and increasing the 

isolation of already declining and 

isolated populations, making them more 

susceptible to genetic drift or 

catastrophic events such as fire, 

flooding, and drought. Further, 

nonagricultural development such as 

gravel mining or housing development 

not only can directly destroy habitat, 

but also can increase fragmentation of 

habitat by increasing associated road 

development. Additionally, draining 

prairie fens will increase invasive plant 

and woody vegetation encroachment. 

Numerous stressors are likely acting 


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cumulatively to further increase impacts 

on the already vulnerable, small, and 

isolated populations of Poweshiek 

skipperling and Dakota skipper. 

Determination 

Dakota Skipper 

We carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the Dakota skipper. 

Dakota skippers are obligate residents of 

undisturbed (remnant, untilled) highquality prairie, ranging from wet-mesic 

tallgrass prairie to dry-mesic mixedgrass prairie. Native tallgrass prairies 

have been reduced by 85 to 99.9 percent 

of their former area, and native mixedgrass prairies have been reduced by 71.9 

to 99 percent of their former area in 

North Dakota, Manitoba, and 

Saskatchewan. The Dakota skipper was 

once a common prairie butterfly widely 

dispersed in five States, extending from 

Illinois to North Dakota, and portions of 

two Canadian provinces. However, its 

range is now substantially reduced such 

that the Dakota skipper is restricted to 

small patches of fragmented nativeprairie remnants in portions of three 

States and two Canadian provinces. 

Recent survey data indicate that the 

Dakota skipper has declined to zero or 

to undetectable levels in approximately 

77 percent of sites where it had been 

recorded rangewide. It is presumed 

extirpated from Illinois and Iowa and no 

longer occurs in eastern Minnesota. 

Much of the rangewide decline in the 

species has been observed in the last 

few years. Since 1988, researchers have 

surveyed 10 or more sites in 25 years; 

the average positive detection rate for 

those years is 63 percent rangewide. 

Since 2009, the percent of surveyed 

sites with positive detections of the 

species has dropped from 63 percent in 

2009, to 41 percent in 2010, 36 percent 

in 2011, 37 percent in 2012, and 22 

percent in 2013. While these types of 

lows in detections have been observed 

in past years, for example, in the early 

1990s, the numbers of individuals 

observed in 2013 were the lowest ever 

recorded, despite extensive survey 

effort. Dakota skippers currently occupy 

sites in northeastern South Dakota, 

North Dakota, western Minnesota, 

southern Manitoba, and southeastern 

Saskatchewan. 

Of the 264 historical locations, the 

species is presumed extirpated or 

possibly extirpated from at least 93 (35 

percent) of those sites, and the 

occupancy of the species is unknown at 

approximately 88 (33 percent) sites. Of 

the 88 sites where the occupancy is 

unknown, at least 78 sites are subject to 

one or more stressors that have a 

moderate to high impact on those 

populations—these sites are distributed 

across Minnesota, North Dakota, and 

South Dakota. Three sites with 

unknown occupancy were not evaluated 

for stressors, due to lack of information. 

The 7 sites with unknown occupancy 

without moderate- to high-level 

stressors are scattered in various 

counties in Minnesota and South 

Dakota, and the skipper is thought to 

still be present at approximately 83 (31 

percent) of the 264 historical locations, 

although 22 of these sites have not been 

surveyed since 2002. Of those 83 sites, 

at least 73 sites are subject to one or 

more stressors that have a moderate to 

high impact on those populations, such 

as conversion to agriculture, lack of 

management, and small size and 

isolation. Four sites were not evaluated 

due to lack of information, and the 

remaining six sites that do not have 

stressors with moderate- to high-level 

impacts to populations occur in 

scattered counties in Minnesota and 

South Dakota. 

Approximately half (40 of 83) of the 

locations where the species is 

considered to be present are primarily 

located on privately owned fall-hayed 

prairies in Canada, mostly within 2 

isolated complexes, and have not been 

surveyed since 2007. All 40 of those 

Canadian sites have one or more 

stressors of moderate to high level of 

impact to populations. Approximately 

15 populations in Canada are on lands 

that are being used in ways that are 

favorable to the Dakota skipper (i.e., 

late-season haying conducted at least 

every other year and there is no 

indication that native plant species 

diversity is declining due to timing or 

frequency of mowing), and the stressors 

at those sites are not immediate. 

However, we are aware of only one of 

these Canadian populations that is 

protected (on Federal land). The 

remaining sites where the species is 

considered to be present are about 

equally distributed among Minnesota 

(11 sites), North Dakota (16 sites), and 

South Dakota (14 sites). Sites with 

stressors with moderate to high level of 

impacts to populations occur in all three 

States. 

Many factors likely contributed to the 

Dakota skipper’s decline, and numerous 

factors, acting individually or 

synergistically, continue today (see 

Summary of Factors Affecting the 

Species). We identified many stressors 

to the species, some of which rise to the 

level of threats that contribute to the 

listing status for each species. Habitat 

loss and degradation have impacted the 

Dakota skipper, curtailing the ranges of 

the species (see Factor A). Extensive 

historical conversion of prairie and 

associated habitats, nearly complete in 

some areas, has isolated many Dakota 

skipper populations. These small and 

isolated populations are subject to loss 

of genetic diversity through genetic drift 

(see Factor E) and are susceptible to a 

variety of stochastic (e.g., wildfires, 

droughts, and floods) and deterministic 

(e.g., overgrazing, invasive species) 

factors (see Factor A) that may kill all 

or a substantial proportion of a 

population. 

Although much of the habitat 

conversion occurred in the past, the 

effects of the dramatic reduction and 

fragmentation of habitat have persistent 

and ongoing effects on the viability of 

populations; furthermore, conversion of 

native prairies to agriculture or other 

uses is still occurring today. The life 

history of the species exacerbates the 

threats caused by the fragmentation and 

degradation of the species’ habitat (see 

Factors A and E) as the Dakota skipper 

is not likely to recolonize distant sites 

due to its short adult life span, single 

annual flight, and limited dispersal 

ability. Therefore, the species’ 

extirpation from a site is likely 

permanent unless it is near another site 

from which it can emigrate. 

Furthermore, because the larvae are 

located at or near the soil surface, they 

are more vulnerable to fire (Factor A); 

herbicides, pesticides, and other 

chemicals (see Factor E); desiccation 

due to changing climate (see Factor E); 

or flooding (see Factor A). 

Within the remaining native-prairie 

patches, degradation of habitat quality is 

now the primary threat to the Dakota 

skipper (see Factor A). Of the various 

threats to Dakota skipper habitat, 

conversion, invasive species, secondary 

succession, and reduction in the 

diversity of native-prairie plant 

communities have moderate- to highlevel impacts to populations throughout 

the range of the Dakota skipper. An 

array of other factors including 

nonagricultural development, chemical 

contaminants, pesticides, and intensive 

grazing are also current and ongoing 

threats to the Dakota skipper and its 

habitat (see Factors A and E). Current 

and ongoing prairie management 

practices, such as indiscriminate use of 

herbicides or intensive grazing that 

reduces or eliminates food sources, 

contribute to the species’ imperilment at 

sites throughout the range of the species 

(see Factors A and E). 

Unknown factors may be the current 

threat that has the most significant 

impacts to the Dakota skipper in Iowa 

and Minnesota, where populations 

experienced a sudden decline to 


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undetectable numbers in the most 

recent years (see Factor E). Based on 

recent data, similar conditions in other 

parts of the Dakota skipper’s range, and 

the similarities in life histories between 

Poweshiek skipperling and Dakota 

skipper, similar declining trends are 

anticipated in other parts of the Dakota 

skipper’s range due to unknown factors, 

and may only be a few years behind 

those declines experienced by other 

species, such as the Poweshiek 

skipperling (see Factor E). Existing 

regulatory mechanisms vary across the 

species’ ranges, and although 

mechanisms do exist that protect the 

species from direct take in Iowa and 

Minnesota, these mechanisms do not 

sufficiently mitigate threats to the 

species (see Factor D). Climate change 

may affect Dakota skipper, especially 

increased frequency of extreme climatic 

conditions such as flooding and 

drought, but there is limited information 

on the exact nature of impacts that these 

species may experience. Recent 

temperature and precipitation trends 

indicate that certain aspects of climate 

change may be occurring in Dakota 

skipper range now (see Factor E). 

The Act defines an endangered 

species as any species that is ‘‘in danger 

of extinction throughout all or a 

significant portion of its range’’ and a 

threatened species as any species ‘‘that 

is likely to become endangered 

throughout all or a significant portion of 

its range within the foreseeable future.’’ 

We find that the Dakota skipper is likely 

to become endangered throughout all of 

its range within the foreseeable future, 

based on the immediacy, severity, and 

scope of the threats described above. 

These threats are exacerbated by small 

population sizes, the loss of redundancy 

and resiliency of these species, and the 

continued inadequacy of existing 

protective regulations. A few scattered 

populations of Dakota skipper are doing 

relatively well, however, and are in 

habitats that have low or non-immediate 

threats. 

Canada has approximately 15 

populations on lands that are being 

utilized in a manner conducive to the 

conservation of Dakota skipper, and the 

threats at those sites are not imminent. 

However, few of these populations are 

protected, many are vulnerable to 

changes in land use, landowners may 

not be aware of the species presence and 

may change land use, and the sites have 

not been surveyed in the last 5 years. 

While a few new locations of Dakota 

skipper populations continue to be 

discovered in North and South Dakota, 

the numbers of individuals observed at 

those sites is generally low, and 

extirpation at previously known sites 

seems to be occurring at a faster rate 

than new discoveries. The decreasing 

numbers of sites with positive 

detections and the decreasing numbers 

of individuals observed at each site 

throughout its range, including known 

sites in Minnesota, North Dakota, and 

South Dakota, is likely to continue. 

Therefore, on the basis of the best 

available scientific and commercial 

information, we are listing the Dakota 

skipper as a threatened species in 

accordance with sections 3(20) and 

4(a)(1) of the Act. 

We find that an endangered species 

status is not appropriate for the Dakota 

skipper because some Dakota skipper 

populations still appear to be doing 

relatively well (populations detected 

during the last survey year, numbers 

appear stable, lower levels of threats 

and stressors)—primarily in North 

Dakota, South Dakota, Manitoba, and 

Saskatchewan. About 14 to 15 sites in 

Manitoba are used in a manner 

conducive to the conservation of Dakota 

skipper (haying after the adult flight 

period), and the threats at those sites are 

not imminent. Furthermore, we believe 

the species to be present in at least 6 

sites that do not have documented 

stressors of a moderate- to high-level 

impact to populations, primarily in 

scattered counties in Minnesota and 

South Dakota. Additionally, a few new 

Dakota skipper sites continue to be 

discovered in suitable prairie habitat in 

North Dakota and South Dakota. 

Under the Act and our implementing 

regulations, a species may warrant 

listing if it is endangered or threatened 

throughout all or a significant portion of 

its range. Because we have determined 

that the Dakota skipper is a threatened 

species throughout all of its range, no 

portion of its range can be ‘‘significant’’ 

for purposes of the definitions of 

‘‘endangered species’’ and ‘‘threatened 

species.’’ See the Final Policy on 

Interpretation of the Phrase ‘‘Significant 

Portion of Its Range’’ in the Endangered 

Species Act’s Definitions of 

‘‘Endangered Species’’ and ‘‘Threatened 

Species’’ (79 FR 37577). 

Poweshiek Skipperling 

We carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the Poweshiek 

skipperling. Poweshiek skipperling are 

obligate residents of undisturbed 

(remnant, untilled) high-quality prairie, 

ranging from wet-mesic tallgrass prairie 

to dry-mesic mixed-grass prairie. Native 

tallgrass prairies have been reduced by 

85 to 99.9 percent of their former area, 

and native mixed-grass prairies have 

been reduced by 72 to 99 percent of 

their former area in North Dakota, 

Manitoba, and Saskatchewan. The 

Poweshiek skipperling was once a 

common prairie butterfly widely 

dispersed in eight States, extended from 

Michigan to North Dakota, and portions 

of Manitoba, Canada. However, its range 

is now substantially reduced such that 

the Poweshiek skipperling is restricted 

to small patches of fragmented nativeprairie remnants in portions of two 

States and one Canadian province. The 

species is presumed extirpated from 

Illinois and Indiana, and the status of 

the species is unknown in four of the six 

States with relatively recent records 

(within the last 20 years). Recent survey 

data indicate that the Poweshiek 

skipperling has declined to zero or to 

undetectable levels in approximately 96 

percent of sites where it has ever been 

recorded. 

A drastic decline in this species has 

been observed rangewide very recently. 

Between 1985 and 2003, researchers 

surveyed 10 or more sites in 7 different 

years (excluding new sites in the first 

year); the average positive detection rate 

for those years is 71 percent rangewide. 

Since 2003, the percent of surveyed 

sites with positive detections of the 

species has dropped to an average of 31 

percent each year (2004–2013), with a 

low of 12 percent at sites surveyed in 

2012 and 2013. Despite recent 

substantial survey efforts in those 

States, the Poweshiek skipperling has 

not been recorded in Iowa since 2007, 

when it was observed at 1 site; in North 

Dakota since 2001, when it was 

observed at 1 site, nor in South Dakota 

since 2008, when it was observed at 3 

sites. The species was not observed in 

North Dakota, South Dakota, or 

Minnesota during 2012 surveys, for 

example. The Poweshiek skipperling 

was observed at one site in Minnesota 

in 2007 and there was a sighting of a 

Poweshiek skipperling at one site in 

2013, although no photographs or 

specimens were taken to confirm the 

sighting. Iowa sites were not surveyed 

in 2012, and the species was not 

detected in 2013. Poweshiek skipperling 

have historically been documented at 

approximately 296 sites; now we 

consider the species to be present at 

only 12 of those sites—one of these is 

considered a sub-site of a larger site. 

The only confirmed extant (present) 

populations of Poweshiek skipperling 

are currently restricted to 1 small and 

isolated native-prairie remnant in 

Wisconsin, 9 small and isolated prairie 

fen remnants in Michigan, and a prairie 

complex in Manitoba. The species may 

also be present at one site in Minnesota. 

These sites represent less than 5 percent 

of the total number of sites ever 


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documented for the species. The 

numbers observed at these sites are 

relatively small (fewer than 100 

individuals at all sites surveyed in 

2013), and all of these sites have at least 

one documented threat that has 

moderate to high impacts on those 

populations. The strongest population 

in the United States, a prairie fen in 

Michigan with relatively high and fairly 

consistent numbers observed each year 

(numbers observed per minute ranged 

from 0.2 to 2.2 during the last 6 survey 

years), for instance, is under threat from 

intense development pressure. The 

Tallgrass Prairie Preserve site in 

Manitoba also has relatively high 

numbers observed each year; however, 

this site is impacted by several 

immediate, moderate- to high-level 

threats, including the encroachment of 

invasive plants and woody vegetation, 

flooding, and isolation from the nearest 

site by hundreds of kilometers. In 

addition, recent unplanned fires in 2009 

and 2011 affected large portions of the 

site. Poweshiek skipperling is 

considered to have unknown occupancy 

at 75 sites—throughout the range of the 

species (Iowa, Michigan, Minnesota, 

North Dakota, and South Dakota), 49 of 

these sites were included in the threats 

assessment. Of the 49 sites where the 

occupancy is unknown that had 

sufficient information to assess, at least 

42 sites are subject to one or more 

threats that have a moderate to high 

impact on those populations. These 

sites are throughout the range of the 

species in Iowa, Michigan, Minnesota, 

North Dakota, and South Dakota. 

Many factors likely contributed to the 

Poweshiek skipperling’s decline, and 

numerous major threats, acting 

individually or synergistically, continue 

today (see Summary of Factors Affecting 

the Species). Habitat loss and 

degradation have impacted the 

Poweshiek skipperling, curtailing the 

ranges of both species (see Factor A). 

Extensive historical conversion of 

prairie and associated habitats, nearly 

complete in some areas, has isolated 

many Poweshiek skipperling 

populations. These small and isolated 

populations are subject to loss of genetic 

diversity through genetic drift (see 

Factor E) and are susceptible to a variety 

of stochastic (e.g., wildfires, droughts, 

and floods) and deterministic (e.g., 

overgrazing, invasive species) factors 

(see Factor A) that may kill all or a 

substantial proportion of a population. 

Although much of the habitat 

conversion occurred in the past, the 

effects of the dramatic reduction and 

fragmentation of habitat have persistent 

and ongoing effects on the viability of 

populations; furthermore, conversion of 

native prairies to agriculture or other 

uses is still occurring today. The life 

history of the species exacerbates the 

threats caused by the fragmentation and 

degradation of its habitat (see Factors A 

and E) as Poweshiek skipperlings are 

not likely to recolonize distant sites due 

to their short adult life span, single 

annual flight, and limited dispersal 

ability. Therefore, the Poweshiek 

skipperling’s extirpation from a site is 

likely permanent unless it is near 

another site from which it can emigrate. 

Furthermore, because the larvae are 

located at or near the soil surface, they 

are more vulnerable to fire (Factor A), 

herbicides, pesticides, and other 

chemicals (see Factor E); desiccation 

due to changing climate (see Factor E); 

or changes in hydrology (see Factor A). 

Within the remaining native-prairie 

patches, degradation of habitat quality is 

now the primary threat to the 

Poweshiek skipperling (see Factor A). 

Of the various threats to Poweshiek 

skipperling habitat, conversion, invasive 

species, secondary succession, and 

reduction in the diversity of nativeprairie plant communities have 

moderate- to high-level impacts to 

populations throughout the range of the 

Poweshiek skipperling. An array of 

other factors including nonagricultural 

development, chemical contaminants, 

pesticides, and intensive grazing are 

also current and ongoing threats to the 

Poweshiek skipperling and its habitat 

(see Factors A and E). Current and 

ongoing prairie management practices, 

such as indiscriminate use of herbicides 

or intensive grazing that reduces or 

eliminates food sources, contribute to 

the species’ imperilment, particularly in 

North Dakota, South Dakota, and 

Minnesota (see Factors A and E). 

Unknown factors may be the current 

threat that has the most significant 

impacts to the Poweshiek skipperling 

species in Iowa, Minnesota, North 

Dakota, and South Dakota, where 

populations experienced a sudden 

decline to undetectable numbers in the 

most recent years (see Factor E). 

Existing regulatory mechanisms vary 

across the species’ ranges, and although 

mechanisms do exist in Iowa, Michigan, 

Minnesota, and Wisconsin that protect 

the species from direct take, these 

mechanisms do not sufficiently mitigate 

threats to the Poweshiek skipperling 

(see Factor D). Climate change may 

affect the Poweshiek skipperling, 

especially increased frequency of 

extreme climatic conditions such as 

flooding and drought, but there is 

limited information on the exact nature 

of impacts that the species may 

experience. Recent temperature and 

precipitation trends indicate that certain 

aspects of climate change may be 

occurring in Poweshiek skipperling 

range now (see Factor E). 

The Act defines an endangered 

species as any species that is ‘‘in danger 

of extinction throughout all or a 

significant portion of its range’’ and a 

threatened species as any species ‘‘that 

is likely to become endangered 

throughout all or a significant portion of 

its range within the foreseeable future.’’ 

We find that the Poweshiek skipperling 

is presently in danger of extinction 

throughout its entire range, based on the 

immediacy, severity, and scope of the 

threats described above. These threats 

are exacerbated by small population 

sizes, the loss of redundancy and 

resiliency of these species, and the 

continued inadequacy of existing 

protective regulations. There are only 12 

locations where we believe the species 

to be present, and all of those sites are 

subject to at least one or more ongoing 

and immediate threats that have 

moderate- to high-level effects on those 

populations. Therefore, on the basis of 

the best available scientific and 

commercial information, we are listing 

the Poweshiek skipperling as 

endangered in accordance with sections 

3(6) and 4(a)(1) of the Act. 

We find that a threatened species 

status is not appropriate for the 

Poweshiek skipperling because the 

unknown factors have significant 

impacts to the species throughout most 

of its range and have occurred in a short 

timeframe. Sharp population declines 

have not been detected at the few 

remaining sites where the species is still 

present, but all of these sites are 

currently experiencing one or more 

threats that have moderate- to high-level 

impacts to populations. Based on recent 

data and similar conditions in other 

parts of Poweshiek skipperling range, 

similar declining trends are anticipated 

in other parts of the range of the species, 

and may only be a few years behind 

those declines experienced by the 

species in Iowa, Minnesota, North 

Dakota, and South Dakota (see Factor E). 

The impacts of the unknown factors on 

populations are exacerbated by habitat 

curtailment and destruction and other 

factors such as the effects of small and 

isolated populations due to habitat 

fragmentation. 

Under the Act and our implementing 

regulations, a species may warrant 

listing if it is endangered or threatened 

throughout all or a significant portion of 

its range. Because we have determined 

that the Poweshiek skipperling is an 

endangered species throughout all of its 

range, no portion of its range can be 


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‘‘significant’’ for purposes of the 

definitions of ‘‘endangered species’’ and 

‘‘threatened species.’’ See the Final 

Policy on Interpretation of the Phrase 

‘‘Significant Portion of Its Range’’ in the 

Endangered Species Act’s Definitions of 

‘‘Endangered Species’’ and ‘‘Threatened 

Species’’ (79 FR 37577). 

Available Conservation Measures 

Conservation measures provided to 

species listed as endangered or 

threatened under the Act include 

recognition, recovery actions, 

requirements for Federal protection, and 

prohibitions against certain practices. 

Recognition through listing results in 

public awareness and conservation by 

Federal, State, Tribal, and local 

agencies, private organizations, and 

individuals. The Act encourages 

cooperation with the States and requires 

that recovery actions be carried out for 

all listed species. The protection 

required by Federal agencies and the 

prohibitions against certain activities 

are discussed, in part, below. 

The primary purpose of the Act is the 

conservation of endangered and 

threatened species and the ecosystems 

upon which they depend. The ultimate 

goal of such conservation efforts is the 

recovery of these listed species, so that 

they no longer need the protective 

measures of the Act. Subsection 4(f) of 

the Act requires the Service to develop 

and implement recovery plans for the 

conservation of endangered and 

threatened species. The recovery 

planning process involves the 

identification of actions that are 

necessary to halt or reverse the species’ 

decline by addressing the threats to its 

survival and recovery. The goal of this 

process is to restore listed species to a 

point where they are secure, selfsustaining, and functioning components 

of their ecosystems. 

Recovery planning includes the 

development of a recovery outline 

shortly after a species is listed, 

preparation of a draft and final recovery 

plan, and revisions to the plan as 

significant new information becomes 

available. The recovery outline guides 

the immediate implementation of urgent 

recovery actions and describes the 

process to be used to develop a recovery 

plan. The recovery plan identifies sitespecific management actions that will 

achieve recovery of the species, 

measurable criteria that determine when 

a species may be downlisted or delisted, 

and methods for monitoring recovery 

progress. Recovery plans also establish 

a framework for agencies to coordinate 

their recovery efforts and provide 

estimates of the cost of implementing 

recovery tasks. Recovery teams 

(comprising species experts, Federal 

and State agencies, nongovernmental 

organizations, and stakeholders) are 

often established to develop recovery 

plans. When completed, the recovery 

outlines, draft recovery plans, and the 

final recovery plans will be available on 

our Web site (http://www.fws.gov/

endangered), or from our Twin Cities 

Ecological Services Fish and Wildlife 

Office (see FOR FURTHER INFORMATION

CONTACT). 

Implementation of recovery actions 

generally requires the participation of a 

broad range of partners, including other 

Federal agencies, States, Tribes, 

nongovernmental organizations, 

businesses, and private landowners. 

Examples of recovery actions include 

habitat restoration (e.g., restoration of 

native vegetation), research, captive 

propagation and reintroduction, and 

outreach and education. The recovery of 

many listed species cannot be 

accomplished solely on Federal lands 

because their range may occur primarily 

or solely on non-Federal lands. To 

achieve recovery of these species 

requires cooperative conservation efforts 

on private, State, and Tribal lands. 

When species are listed, funding for 

recovery actions will be available from 

a variety of sources, including Federal 

budgets, State programs, and cost-share 

grants for non-Federal landowners, the 

academic community, and 

nongovernmental organizations. In 

addition, pursuant to section 6 of the 

Act, the States of Iowa, Michigan, 

Minnesota, North Dakota, South Dakota, 

and Wisconsin would be eligible for 

Federal funds to implement 

management actions that promote the 

protection and recovery of the 

Poweshiek skipperling and Dakota 

skipper. Information on our grant 

programs that are available to aid 

species recovery can be found at: 

http://www.fws.gov/grants. 

Please let us know if you are 

interested in participating in recovery 

efforts for the Dakota skipper or 

Poweshiek skipperling. Additionally, 

we invite you to submit any new 

information on these species whenever 

it becomes available and any 

information you may have for recovery 

planning purposes (see FOR FURTHER

INFORMATION CONTACT). 

Section 7(a) of the Act requires 

Federal agencies to evaluate their 

actions with respect to any species that 

is proposed or listed as endangered or 

threatened and with respect to its 

critical habitat, if any is designated. 

Regulations implementing this 

interagency cooperation provision of the 

Act are codified at 50 CFR part 402. If 

a species is listed subsequently, section 

7(a)(2) of the Act requires Federal 

agencies to ensure that activities they 

authorize, fund, or carry out are not 

likely to jeopardize the continued 

existence of the species or destroy or 

adversely modify its critical habitat. If a 

Federal action may adversely affect a 

listed species or its critical habitat, the 

responsible Federal agency must enter 

into formal consultation with the 

Service. 

Federal agency actions within the 

species habitat that may require 

conference or consultation or both as 

described in the preceding paragraph 

include, but are not limited to, 

management and any other landscapealtering activities on Federal lands such 

as actions within the jurisdiction of the 

NRCS; land management by the U.S. 

Forest Service; issuance of section 404 

Clean Water Act permits by the U.S. 

Army Corps of Engineers; land 

management by the U.S. Fish and 

Wildlife Service; construction and 

management of gas pipeline, wind 

facilities and associated infrastructure, 

and power line rights-of-way by the 

Federal Energy Regulatory Commission; 

construction and maintenance of roads 

or highways by the Federal Highway 

Administration; and land management 

within branches of the Department of 

Defense (DOD). Examples of these types 

of actions include activities funded or 

authorized under the Farm Bill Program, 

Environmental Quality Incentives 

Program, Clean Water Act (33 U.S.C. 

1251 et seq.), Partners for Fish and 

Wildlife Program, and DOD 

construction activities related to 

training or other military missions. 

Poweshiek Skipperling 

The Act and its implementing 

regulations set forth a series of general 

prohibitions and exceptions that apply 

to all endangered wildlife. The 

prohibitions of section 9(a)(2) of the Act, 

codified at 50 CFR 17.21 for endangered 

wildlife, in part, make it illegal for any 

person subject to the jurisdiction of the 

United States to take (includes harass, 

harm, pursue, hunt, shoot, wound, kill, 

trap, capture, or collect; or to attempt 

any of these), import, export, ship in 

interstate commerce in the course of 

commercial activity, or sell or offer for 

sale in interstate or foreign commerce 

any listed species. Under the Lacey Act 

(18 U.S.C. 42–43; 16 U.S.C. 3371–3378), 

it is also illegal to possess, sell, deliver, 

carry, transport, or ship any such 

wildlife that has been taken illegally. 

Certain exceptions apply to agents of the 

Service and State conservation agencies. 


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63744 Federal Register / Vol. 79, No. 206 / Friday, October 24, 2014 / Rules and Regulations 

Dakota Skipper 

Under section 4(d) of the Act, the 

Service has discretion to issue 

regulations that we find necessary and 

advisable to provide for the 

conservation of threatened wildlife. We 

may also prohibit by regulation with 

respect to threatened wildlife any act 

prohibited by section 9(a)(1) of the Act 

for endangered wildlife. Exercising this 

discretion, the Service has developed a 

4(d) rule containing all the general 

prohibitions and exceptions to those 

prohibitions; these are found at 50 CFR 

17.31 and 50 CFR 17.32. For the Dakota 

skipper, the Service has developed a 

4(d) rule that is tailored to the specific 

threats and conservation needs of this 

species. As a means to promote 

conservation efforts on behalf of the 

Dakota skipper, we are finalizing a 4(d) 

rule for this species that modifies the 

standard protections for threatened 

wildlife found at 50 CFR 17.31. In the 

case of a 4(d) rule, the general 

regulations (50 CFR 17.31 and 17.71) 

applying most prohibitions under 

section 9 of the Act to threatened 

species do not apply to that species, and 

the 4(d) rule contains the prohibitions 

necessary and advisable to conserve that 

species. 

As discussed above, the primary 

factors supporting the determination of 

threatened species status for the Dakota 

skipper are habitat loss and degradation 

of native prairies, including conversion 

of native prairie for agriculture or other 

development; ecological succession and 

encroachment of invasive species and 

woody vegetation; certain fire, haying, 

and grazing management that reduces 

the availability of certain native-prairie 

grasses and flowering herbaceous plants 

to the Dakota skipper; some fire 

management; flooding; existing 

regulatory mechanisms that are 

inadequate to mitigate threats to the 

species; loss of genetic diversity; small 

size and isolation of remnant patches of 

native prairie; indiscriminate use of 

herbicides that reduces or eliminates 

nectar sources; climate conditions such 

as drought; and other unknown factors. 

The Act does not specify particular 

prohibitions, or exceptions to those 

prohibitions, for threatened species. 

Instead, under section 4(d) of the Act, 

the Secretary of the Interior has the 

discretion to issue such regulations as 

she deems necessary and advisable to 

provide for the conservation of such 

species. The Secretary also has the 

discretion to prohibit by regulation with 

respect to any threatened species, any 

act prohibited under section 9(a)(1) of 

the Act. Exercising this discretion, the 

Service has developed general 

prohibitions (50 CFR 17.31) and 

exceptions to those prohibitions (50 

CFR 17.32) under the Act that apply to 

most threatened species. Alternately, for 

other threatened species, the Service 

develops specific prohibitions and 

exceptions that are tailored to the 

specific conservation needs of the 

species. In such cases, some of the 

prohibitions and authorizations under 

50 CFR 17.31 and 17.32 may be 

appropriate for the species and 

incorporated into a rule under section 

4(d) of the Act, but the section 4(d) rule 

will also include provisions that are 

tailored to the specific conservation 

needs of the threatened species and may 

be more or less restrictive than the 

general provisions at 50 CFR 17.31. 

In recognition of efforts that provide 

for conservation and management of the 

Dakota skipper and its habitat in a 

manner consistent with the purposes of 

the Act, this 4(d) rule outlines the 

prohibitions, and exceptions to those 

prohibitions, necessary and advisable 

for the conservation of the Dakota 

skipper. 

Conversion of grasslands for the 

production of agricultural crops poses a 

threat to the Dakota skipper because it 

may directly destroy the species’ 

habitat, increase isolation of 

populations by impeding dispersal, and 

increase the risk posed by drift of 

herbicides and pesticides. A wide 

variety of peer-reviewed publications 

and government reports have 

documented recent conversion of native 

grassland. In addition, economic and 

policy incentives are likely to continue 

to place pressure on landowners to 

convert native grassland from ranching 

to agricultural cropland (Doherty et al. 

2013, p. 14); Sylvester et al. 2013, p. 13; 

Rashford et al. 2011, p. 282; Stephens et 

al. 2008, p. 6; (Congressional Research 

Service (CRS) 2007, p. 5, United States 

Government Accountability Office 

(USGAO) 2007, p. 15, Stephens et al. 

2008, p. 6, Rashford et al. 2011, p. 282, 

Sylvester et al. 2013, p. 13). Grassland 

loss in the western corn belt may be 

occurring at the fastest rate observed 

since the 1920s and 1930s and at a rate 

comparable to that of deforestation in 

Brazil, Malaysia, and Indonesia (Wright 

and Wimberly 2013, p. 5). Between 2006 

and 2011, destruction of native 

grassland was mostly concentrated in 

North Dakota and South Dakota, east of 

the Missouri River, an area 

corresponding closely to the range of the 

Dakota skipper (Wright and Wimberly 

2013, p. 2). In northeastern South 

Dakota, one of the few remaining 

strongholds for the Dakota skipper, 

about 269,000 acres (108,907 ha) of 

grassland was lost—primarily to 

cropland—between 2006 and 2012 

(Reitsma et al. 2014, p. 3). 

As with agricultural policies (Doherty 

et al. 2013, p. 15), prohibitions against 

take of Dakota skippers could interact 

with other factors to affect the rates at 

which native grassland is converted in 

the range of the species. Less than 20 

percent of the grassland in the Prairie 

Pothole Region of the United States is 

permanently protected (Doherty et al. 

2013, p. 7), and the vast majority of 

remaining grassland is privately owned. 

The conservation of ‘‘working 

landscapes’’ based on ranching and 

livestock operations (‘grass-based 

farming’) is frequently a priority of 

programs to conserve native grassland 

ecosystems in the northern Great Plains 

(e.g., U.S. Fish and Wildlife Service 

2011, p. 5). Exempting incidental take of 

Dakota skippers that may result from 

grazing and other routine livestock 

ranching activities will afford us more 

time to protect the species’ habitats in 

these areas and will facilitate the 

cooperation and partnerships with 

livestock producers necessary to recover 

the species. 

Three primary factors have led us to 

determine that it is necessary and 

advisable to exempt take of Dakota 

skippers caused by certain ranching 

activities, including grazing. First, a 

variety of socioeconomic and policy 

factors are leading to the conversion of 

native grasslands for the production of 

agricultural crops, as summarized 

above. Whereas conversion of native 

grassland for crop production would 

result in a permanent loss of Dakota 

skipper habitat and may also exacerbate 

other threats (e.g., pesticide drift) to the 

species, grasslands can remain suitable 

for Dakota skippers when grazed (see 

below and Dana 1991, p. 54; Schlicht 

1997, p. 5; Skadsen 1997, pp. 24–29). By 

exempting take of Dakota skippers 

caused by grazing, we acknowledge the 

positive role that some ranchers have 

already played in conserving Dakota 

skippers and the importance of 

preventing any additional loss and 

fragmentation of native grasslands as the 

result of activities in areas that could 

support the species. 

Second, although some grazing 

practices pose a threat to Dakota 

skipper, grazing may also be an effective 

tool to improve Dakota skipper habitat 

when carefully applied in cooperation 

and consultation with private 

landowners, public land managers, and 

grazing experts. In eastern South 

Dakota, Dakota skipper populations 

were deemed secure at some sites 

managed with rotational grazing that 

was sufficiently light to maintain native 

plant species diversity (Skadsen 1997, 


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pp. 24–29), and grazing may also benefit 

Dakota skippers by increasing coverage 

of mid-height grasses, such as little 

bluestem, relative to tallgrasses, such as 

big bluestem and Indiangrass (Dana 

1991, p. 54). Intensive early-season 

grazing can reduce the extent of 

Kentucky bluegrass, a nonnative species 

that invades prairie habitats and 

competes with native plant species 

(DeKeyser et al. 2013, p. 86). In 

addition, grazing may also inhibit the 

establishment of smooth brome and 

help to enhance coverage and diversity 

of native plants in prairies that have 

been invaded by nonnative cool-season 

grasses (U.S. Fish and Wildlife Service 

2006, p. 2; DeKeyser et al. 2009, p. 18; 

Smart et al. 2013, p. 686). Because 

grazing can lead to adverse conditions 

for the Dakota skipper, however, the 

Service encourages collaboration with 

private landowners, public land 

managers (e.g., Skadsen 2006, p. 5), 

State and Federal conservation agencies, 

and nongovernmental organizations to 

identify, implement, monitor, and refine 

grazing practices that are conducive to 

the species’ conservation. 

Third, recovery of the Dakota skipper 

will depend on the protection and 

restoration of high-quality habitats for 

the species on private lands and on 

public lands that are grazed or hayed by 

private individuals under lease or other 

agreements. Conservation of Dakota 

skippers on these lands will require the 

development and implementation of 

complex, individualized, and long-term 

management agreements that rely on 

robust monitoring of Dakota skipper 

populations and habitat features. All of 

these agreements will require a 

willingness on the part of the private 

ranchers to collaborate with the Service 

and our partners to implement, monitor, 

and adapt conservation grazing 

practices in a manner that allows for 

stable or growing Dakota skipper 

populations. This type of cooperative 

approach is more likely to take place 

and to be successful if we exempt take 

caused by grazing and the other 

activities that we specify in the 4(d) 

rule. 

In some geographic areas, such as 

McHenry County, North Dakota, the 

Dakota skipper almost exclusively 

inhabits relatively flat and moist prairie 

habitats that are mowed for hay. In these 

areas we do not encourage a switch to 

grazing without careful consideration of 

the potential consequences to the 

Dakota skipper. These habitats, referred 

to as calcareous or ‘‘alkaline prairies’’ by 

McCabe (1979, p. 17; 1981, p. 179); ‘‘wet 

mesic’’ by Royer and Marrone (1992, p. 

21); and ‘‘Type A’’ by Royer et al. (2008, 

p. 14), are distinguished from other 

Dakota skipper habitats by relatively flat 

topography and certain plant 

community and soil characteristics 

(Lenz 1999, pp. 5–7; Royer et al. 2008, 

pp. 14–15). Dakota skippers appear to be 

generally absent from this type of 

habitat in North Dakota where it is 

grazed, due to a shift away from a plant 

community that is suitable for the 

species (McCabe 1979, p. 17; 1981, p. 

179). The shift in plant community 

composition and adverse effects to 

Dakota skipper populations may occur 

rapidly (McCabe 1981, p. 179; Royer 

and Royer 1998, p. 23). The conversion 

of similar habitats in Manitoba from 

haying to grazing may be a major threat 

to the Dakota skipper there as well 

(Webster 2007, pp. i–ii, 6). In contrast, 

limited or ‘‘light rotational grazing’’ of 

habitats on steep dry-mesic slopes in 

Saskatchewan may not conflict with 

Dakota skipper conservation (Webster 

2007, p. ii). 

The reduced vulnerability of habitats 

on dry-mesic slopes to the effects of 

grazing may be due, in part, to the 

tendency for grazing pressure to be 

lighter in sloped areas. The steepness of 

habitats occupied by Dakota skippers in 

Saskatchewan, for example, limits their 

use for grazing (Webster 2007, p. ii). 

Steep slopes may also play a role in 

reducing the adverse effects of grazing at 

some sites in South Dakota—at one 

grazed site inhabited by the Dakota 

skipper, for example, habitat on steep 

slopes was ‘‘in good condition,’’ 

whereas ‘‘lesser slopes’’ were 

‘‘moderately grazed’’ and some areas 

were ‘‘overgrazed’’ (Skadsen 1999a, p. 

29). 

In the proposed rule, we cited the lack 

of any examples of strong populations of 

Dakota skippers where the relatively 

moist and flat (‘Type A’) habitats are 

grazed as evidence that it would not be 

necessary and advisable to exempt take 

caused by grazing in certain counties 

where ‘Type A’ habitats are found. As 

stated above, we still do not recommend 

a change to grazing on ‘Type A’ habitats 

occupied by the Dakota skipper unless 

a cooperative plan is developed to 

ensure that it will be done in a manner 

that conserves the species in the 

affected habitats. Nevertheless, in light 

of the great importance that cooperative 

relationships with certain public land 

management agencies and private 

livestock producers will play in 

conserving the Dakota skipper, we find 

that it is necessary and advisable to 

exempt take that may be caused by 

grazing on non-Federal lands regardless 

of geographic area. We do not expect 

this to result in a significant change in 

management from haying to grazing 

because other factors, such as the costs 

of building fences and developing 

livestock watering facilities, are more 

important factors that will influence this 

land management decision. 

Provisions of the 4(d) Rule for the 

Dakota Skipper 

Section 4(d) of the Act states that ‘‘the 

Secretary shall issue such regulations as 

[s]he deems necessary and advisable to 

provide for the conservation’’ of species 

listed as a threatened species. 

Conservation is defined in the Act to 

mean ‘‘to use and the use of all methods 

and procedures which are necessary to 

bring any endangered species or 

threatened species to the point at which 

the measures provided pursuant to [the 

Act] are no longer necessary.’’ 

Additionally, section 4(d) states that the 

Secretary ‘‘may by regulation prohibit 

with respect to any threatened species 

any act prohibited under section 

9(a)(1).’’ 

The courts have recognized the extent 

of the Secretary’s discretion under this 

standard to develop rules that are 

appropriate for the conservation of a 

species. For example, the Secretary may 

find that it is necessary and advisable 

not to include a taking prohibition, or to 

include a limited taking prohibition. See 

Alsea Valley Alliance v. Lautenbacher, 

2007 U.S. Dist. Lexis 60203 (D. Or. 

2007); Washington Environmental 

Council v. National Marine Fisheries 

Service, and 2002 U.S. Dist. Lexis 5432 

(W.D. Wash. 2002). In addition, as 

affirmed in State of Louisiana v. Verity, 

853 F.2d 322 (5th Cir. 1988), the rule 

need not address all the threats to the 

species. As noted by Congress when the 

Act was initially enacted, ‘‘once an 

animal is on the threatened list, the 

Secretary has an almost infinite number 

of options available to him with regard 

to the permitted activities for those 

species. [S]he may, for example, permit 

taking, but not importation of such 

species,’’ or [s]he may choose to forbid 

both taking and importation but allow 

the transportation of such species, as 

long as the measures will ‘‘serve to 

conserve, protect, or restore the species 

concerned in accordance with the 

purposes of the Act’’ (H.R. Rep. No. 412, 

93rd Cong., 1st Sess. 1973). 

Section 9 prohibitions make it illegal 

for any person subject to the jurisdiction 

of the United States to take (including 

harass, harm, pursue, shoot, wound, 

kill, trap, capture, or collect; or attempt 

any of these), import or export, ship in 

interstate commerce in the course of 

commercial activity, or sell or offer for 

sale in interstate or foreign commerce 

any wildlife species listed as an 

endangered species, without written 

authorization. It also is illegal under 


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section 9(a)(1) of the Act to possess, sell, 

deliver, carry, transport, or ship any 

such wildlife that is taken illegally. 

Prohibited actions consistent with 

section 9 of the Act are outlined for 

threatened species in 50 CFR 17.31(a) 

and (b). Through this 4(d) rule, all 

prohibitions in 50 CFR 17.31(a) and (b) 

apply to the Dakota skipper except in 

the specific instances as outlined below. 

The 4(d) rule will not remove or alter in 

any way the consultation requirements 

under section 7 of the Act. 

Routine Livestock Operations and 

Maintenance of Recreational Trails and 

Rights-of-Way 

Incidental take that is caused by the 

routine livestock ranching and other 

specified trail and rights-of-way 

maintenance activities described below 

and that are implemented on private, 

State, and tribal lands and on other 

lands not under Federal jurisdiction 

(e.g. lands owned by county 

governments or local governments) will 

not be prohibited, as long as those 

activities are otherwise legal and 

conducted in accordance with 

applicable State, Federal, tribal, and 

local laws and regulations. For the 

purposes of this 4(d) rule, routine 

livestock ranching and recreational trail 

and rights-of-way maintenance activities 

include the items listed below. Except 

as explicitly stated below, these 

activities must be associated with 

livestock ranching for this 4(d) rule to 

apply. 

(1) Fence Construction and 

Maintenance: Fences are an essential 

tool for livestock and ranch 

management. In addition, the strategic 

distribution of fencing is also necessary 

to implement multi-cell rotational 

grazing systems, which may be 

necessary to improve grazing 

management and provide a conservation 

benefit to Dakota skipper habitat. 

(2) Livestock Gathering and 

Management: The installation and 

maintenance of corrals, loading chutes, 

and other livestock working facilities 

are critical to ranch operations. These 

activities may be carried out with only 

minimal impacts to Dakota skipper if 

carefully sited with respect to the 

location and distribution of important 

Dakota skipper habitat. 

(3) Development and Maintenance of 

Livestock Watering Facilities: Without a 

suitable water source in a pasture, 

livestock ranching is impossible. The 

proper distribution of livestock watering 

sources is also a prerequisite to 

implementing improved grazing 

management via the use of multi-cell 

rotational grazing systems that may be 

necessary to conserve Dakota skipper 

habitat and to provide a conservation 

benefit to the species on grazed sites. 

This activity includes both the initial 

development of water sources and their 

maintenance. Dugout ponds, for 

example, typically require a cleanout 

after 15 to 20 years. 

(4) Noxious Weed Control: State and 

county laws require landowners to 

control noxious weeds on their 

property, and the timing of control 

actions is usually dependent on the 

growth stage of the weed species. 

Control of noxious weeds may also be 

important to protect Dakota skipper 

habitat because native plant diversity 

declines when nonnative plant species 

invade and become established in 

prairies (Boettcher et al. 1993, p. 35). 

Broadcast application of herbicides, 

however, may result in significant 

deterioration of native plant diversity in 

prairies (Smart et al. 2011, p. 184). 

Therefore, incidental take of Dakota 

skipper that may result from spraying of 

herbicides would be exempt except as a 

result of broadcast spraying, which we 

define as the application of herbicides 

evenly across the entire application 

area. Note that herbicide applications 

would not affect the Dakota skipper if 

they do not affect the limited areas 

where the species is present. Broadcast 

applications of herbicides that do not 

affect habitats occupied by the Dakota 

skipper would not result in take of the 

species, and thus would not result in 

violation of section 9 of the Act. Take 

that may occur as a result of mowing 

that is carried out for the purpose of 

controlling one or more noxious weed 

species is also exempted from the take 

prohibitions under section 9 of the Act 

by issuance of this 4(d) rule. 

(5) Haying: Stock cows need to be 

maintained through the non-growing 

season though supplemental feeding 

with hay; thus, haying (cutting grass and 

other vegetation for drying and use as 

livestock feed) is a critical component of 

ranch activity. Dakota skippers occur on 

several native hayland sites—sites 

where the native-prairie vegetation is 

mowed for hay. For the purposes of this 

rule, native hayland does not include 

lands that had previously been plowed 

and were then replanted to native or 

nonnative vegetation. Native hayland 

may include, however, areas within 

transportation (e.g., road, highway, 

railroad) rights-of-ways and corridors 

where native grassland is mowed for 

hay. Native haylands are typically cut in 

August, after the needlegrass 

(Hesperostipa spp. or Nassella viridula, 

or both) awns drop. Incidental take of 

Dakota skippers that occurs as a result 

of haying no earlier than July 16 (after 

July 15) is exempted from the take 

prohibitions under section 9 of the Act 

by issuance of this 4(d) rule. Dakota 

skippers are unlikely to occur in 

replanted grasslands (grasslands 

replanted on formerly plowed or 

cultivated lands) or in tame hayland or 

grassland (hayland or grassland planted 

to and comprising primarily nonnative 

grass species, such as smooth brome 

(Bromus inermis inermis)). Therefore, 

mowing replanted and tame grasslands 

before July 16 would not result in take 

of Dakota skippers and would thus not 

result in a violation of section 9 of the 

Act. 

(6) Mowing Section Line Rights-ofWay and Recreational Trails: Section 

line rights-of-way and some recreational 

trails need to be mowed several times 

during the growing season to ensure that 

snow will not catch and block vehicle 

access and that they are suitable for 

hiking and other intended recreational 

activities, respectively. Section line 

rights-of-way typically comprise 

disturbed soil that has been contoured 

for a roadway and are likely to contain 

only small proportions of Dakota 

skipper habitat at any affected site. 

Therefore, impacts to Dakota skipper 

populations are likely to be minimal, 

and any incidental take that is a result 

of mowing of section line rights-of-way 

and recreational trails will be exempt 

from the take prohibitions of section 9 

of the Act. Recreational trails are travel 

ways established either through 

construction or use that are intended for 

and passable by at least one or more of 

the following: foot traffic, bicycles, inline skates, wheelchairs, or crosscountry skis. Incidental take that may be 

caused by mowing recreational trails 

does not need to be associated with 

livestock ranching for the 4(d) rule to 

apply. 

(7) Livestock (Cattle, Bison, or Horse) 

Grazing: Incidental take of Dakota 

skippers that may result from grazing on 

private, State, or tribal land is exempt 

from the take prohibitions of section 9 

of the Act. 

We may issue permits to carry out 

otherwise prohibited activities 

involving endangered and threatened 

wildlife species under certain 

circumstances. Regulations governing 

permits are codified at 50 CFR 17.22 for 

endangered species, and at 17.32 for 

threatened species. With regard to 

endangered wildlife, a permit must be 

issued for the following purposes: For 

scientific purposes, to enhance the 

propagation or survival of the species, 

and for incidental take in connection 

with otherwise lawful activities. 

It is our policy, as published in the 

Federal Register on July 1, 1994 (59 FR 

34272), to identify to the maximum 


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Federal Register / Vol. 79, No. 206 / Friday, October 24, 2014 / Rules and Regulations 63747 

extent practicable at the time a species 

is listed, those activities that would or 

would not constitute a violation of 

section 9 of the Act. The intent of this 

policy is to increase public awareness of 

the effect of a final listing on proposed 

and ongoing activities within the range 

of a listed species. Based on the best 

available information, the following 

actions are unlikely to result in a 

violation of section 9, if these activities 

are carried out in accordance with 

existing regulations and permit 

requirements; this list is not 

comprehensive: 

(1) Unauthorized collecting, handling, 

possessing, selling, delivering, carrying, 

or transporting of the species, including 

import or export across State lines and 

international boundaries, except for 

properly documented antique 

specimens of these taxa at least 100 

years old, as defined by section 10(h)(1) 

of the Act; 

(2) Unauthorized modification, 

removal, or destruction of the prairie 

vegetation, soils, or hydrology in which 

the Dakota skipper and Poweshiek 

skipperling are known to occur; 

(3) The unauthorized release of 

biological control agents that attack any 

life stage of these species, including the 

unauthorized use of herbicides, 

pesticides, or other chemicals in 

habitats in which the Poweshiek 

skipperling or Dakota skipper is known 

to occur; 

(4) Introduction of nonnative species 

that compete with or prey upon the 

Dakota skipper and Poweshiek 

skipperling or their food sources, such 

as the introduction of nonnative leafy 

spurge, reed canary grass, or glossy 

buckthorn, to the State of Iowa, 

Michigan, Minnesota, North Dakota, 

South Dakota, and Wisconsin; and 

(5) Unauthorized discharge of 

chemicals or fill material into any 

wetlands in which the Poweshiek 

skipperling or Dakota skipper are 

known to occur. 

Questions regarding whether specific 

activities would constitute a violation of 

section 9 of the Act should be directed 

to the Twin Cities Ecological Services 

Fish and Wildlife Office (see FOR

FURTHER INFORMATION CONTACT). 

Requests for copies of the regulations 

concerning listed animals and general 

inquiries regarding prohibitions and 

permits may be addressed to the U.S. 

Fish and Wildlife Service, Endangered 

Species Permits, 5600 American Blvd., 

West, Suite 990, Bloomington, MN 

(telephone 612–713–5350; facsimile 

612–713–5292). 

Required Determinations 

National Environmental Policy Act (42 

U.S.C. 4321 et seq.) 

We have determined that 

environmental assessments and 

environmental impact statements, as 

defined under the authority of the 

National Environmental Policy Act 

(NEPA; 42 U.S.C. 4321 et seq.), need not 

be prepared in connection with listing 

a species as an endangered or 

threatened species under the 

Endangered Species Act. We published 

a notice outlining our reasons for this 

determination in the Federal Register 

on October 25, 1983 (48 FR 49244). 

Government-to-Government 

Relationship With Tribes 

In accordance with the President’s 

memorandum of April 29, 1994 

(Government-to-Government Relations 

with Native American Tribal 

Governments; 59 FR 22951), Executive 

Order 13175 (Consultation and 

Coordination With Indian Tribal 

Governments), and the Department of 

the Interior’s manual at 512 DM 2, we 

readily acknowledge our responsibility 

to communicate meaningfully with 

recognized Federal Tribes on a 

government-to-government basis. In 

accordance with Secretarial Order 3206 

of June 5, 1997 (American Indian Tribal 

Rights, Federal-Tribal Trust 

Responsibilities, and the Endangered 

Species Act), we readily acknowledge 

our responsibilities to work directly 

with tribes in developing programs for 

healthy ecosystems, to acknowledge that 

tribal lands are not subject to the same 

controls as Federal public lands, to 

remain sensitive to Indian culture, and 

to make information available to tribes. 

The Sisseton-Wahpeton Oyate, 

Flandreau Santee Sioux Tribe, Turtle 

Mountain Band of Chippewa, Three 

Affiliated Tribes, Spirit Lake Sioux 

Tribe, and Standing Rock Sioux Tribe 

are the main Tribes affected by this final 

rule. We began government-togovernment consultation with these 

tribes prior to the publication of the 

proposed rule, through the public 

comment period, and during the 

development of the final listing 

determination. 

We sent letters in September 2012 to 

each Tribe seeking early input regarding 

the species status review and to offer 

government-to-government 

consultation. We sent notification letters 

in October and November of 2013 to 

each Tribe describing the critical habitat 

exclusion process under section 4(b)(2) 

of the Act, and we engaged in 

conversation with the Tribes about the 

proposed listing and critical habitat 

rules to the extent possible. We have 

maintained contact with Flandreau 

Santee Sioux Tribe, Turtle Mountain 

Chippewa, Three Affiliated Tribes, 

Spirit Lake Sioux Tribe, and Standing 

Rock Sioux Tribe through letters, phone 

calls, and emails, and we notified each 

tribe when documents pertaining to the 

listing and critical habitat rules were 

made available. 

We have coordinated several survey 

efforts with Sisseton-Wahpeton Oyate 

since 1995 and held an informational 

meeting for the Tribe in April 2014, to 

better explain the proposed listing and 

designation of critical habitat. We met 

with representatives from the Turtle 

Mountain Chippewa in May 2014, and 

conducted a site visit at that time to 

evaluate areas proposed for designation 

as critical habitat. We did not receive 

comments from the Sisseton-Wahpeton 

Oyate, Three Affiliated Tribes, Standing 

Rock Sioux Tribe, Flandreau Santee 

Sioux Tribe, Turtle Mountain 

Chippewa, or the Spirit Lake Nation. 

However, notification of the available 

economic analysis screening 

memorandum for the critical habitat 

proposal was provided to all Tribes in 

the species’ ranges at the time it was 

made available to the public. 

References Cited 

A complete list of references cited in 

this rulemaking is available on the 

Internet at http://www.regulations.gov 

and upon request from the Twin Cities 

Ecological Services Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Authors 

The primary authors of this final rule 

are the staff members of the Twin Cities 

Ecological Services Field Office. 

List of Subjects in 50 CFR Part 17 

Endangered and threatened species, 

Exports, Imports, Reporting and 

recordkeeping requirements, 

Transportation. 

Regulation Promulgation 

Accordingly, we amend part 17, 

subchapter B of chapter I, title 50 of the 

Code of Federal Regulations, as follows: 

PART 17—[AMENDED] 

■ 1. The authority citation for part 17 

continues to read as follows: 

Authority: 16 U.S.C. 1361–1407; 1531– 

1544; 4201–4245; unless otherwise noted. 

■ 2. Amend § 17.11(h) by adding entries 

for ‘‘Skipper, Dakota’’ and ‘‘Skipperling, 

Poweshiek’’ to the List of Endangered 

and Threatened Wildlife in alphabetical 

order under ‘‘Insects’’ to read as follows: 


asabaliauskas on DSK5VPTVN1PROD with RULES
63748 Federal Register / Vol. 79, No. 206 / Friday, October 24, 2014 / Rules and Regulations 

§ 17.11 Endangered and threatened 

wildlife. 

* * * * * 

(h) * * * 

Species 

Historic range 

Vertebrate 

population where 

endangered or 

threatened 

Status When listed Critical 

habitat 

Special 

rules Common name Scientific name 

*******

INSECTS

* * * * * * * 

Skipper, Dakota ... Hesperia dacotae U.S.A. (IA, IL, 

MN, ND, SD); 

Canada (Manitoba, Saskatchewan).

NA T 851 NA 17.47(b) 

* * * * * * * 

Skipperling, 

Poweshiek.

Oarisma 

poweshiek.

U.S.A. (IA, IL, IN, 

MI, MN, ND, 

SD, WI,); Canada (Manitoba).

NA E 851 NA NA 

* * * * * * * 

* * * * * 

■ 3. Amend § 17.47 by adding paragraph 

(b) to read as follows: 

§ 17.47 Special rules—insects. 

* * * * * 

(b) Dakota skipper (Hesperia dacotae). 

(1) Which populations of the Dakota 

skipper are covered by this special rule? 

This rule covers the distribution of 

Dakota skipper in the United States. 

(2) Prohibitions. Except as noted in 

paragraph (b)(3) of this section, all 

prohibitions and provisions of §§ 17.31 

and 17.32 apply to the Dakota skipper. 

(3) Exemptions from prohibitions. 

Incidental take of Dakota skipper will 

not be a violation of section 9 of the Act 

if it occurs as a result of the following 

activities (except where explicitly stated 

otherwise, these activities must be 

associated with livestock ranching): 

(i) Fence construction and 

maintenance. 

(ii) Livestock gathering and 

management. The installation and 

maintenance of corrals, loading chutes, 

and other livestock working facilities 

must be carefully sited with respect to 

the location and distribution of 

important Dakota skipper habitat. 

(iii) Development and maintenance of 

livestock watering facilities. 

(iv) Noxious weed control. Incidental 

take of Dakota skipper that results from 

spraying of herbicides is not a violation 

of section 9 of the Act, except such take 

that results from broadcast spraying, 

which is the application of herbicides 

evenly across the entire application 

area. Incidental take that results from 

mowing to control one or more noxious 

weed species would also not be a 

violation of section 9 of the Act. 

(v) Haying. For the purposes of this 

rule, native haylands do not include 

lands that had previously been plowed 

and were then replanted to native or 

nonnative vegetation, but native 

haylands do include areas within 

transportation (e.g., road, highway, 

railroad) rights-of-ways and corridors 

where native grasses are mowed for hay. 

Haying of native haylands no earlier 

than July 16 (after July 15) would not be 

a violation of section 9 of the Act. 

Mowing of replanted grasslands 

(grasslands replanted on formerly 

plowed or cultivated lands) or tame 

haylands or grasslands (planted hayland 

or grassland comprising primarily 

nonnative grass species, such as smooth 

brome (Bromus inermis inermis)) would 

also not be a violation of section 9 of the 

Act at any time of the year. 

(vi) Mowing section line rights-of-way 

and recreational trails. Mowing of 

section line rights-of-way (typically 

disturbed soil that has been contoured 

for a roadway) would not be a violation 

of section 9 of the Act. Mowing of 

recreational trails (travelways 

established either through construction 

or use that are intended for and passable 

by foot traffic, bicycles, in-line skates, 

wheelchairs, or cross-country skis) 

would not be a violation of section 9 of 

the Act, regardless of whether the trails 

are associated with livestock ranching. 

(vii) Livestock (cattle, bison, or horse) 

grazing on private, State, or tribal land. 

Dated: October 15, 2014. 

Stephen Guertin, 

Acting Director, U.S. Fish and Wildlife 

Service. 

[FR Doc. 2014–25190 Filed 10–23–14; 8:45 am] 

BILLING CODE 4310–55–P 


asabaliauskas on DSK5VPTVN1PROD with RULES