6660 Federal Register / Vol. 73, No. 24 / Tuesday, February 5, 2008 / Proposed Rules 

the direct final notice of deletion, and 

it will not take effect. We will, as 

appropriate, address all public 

comments in a subsequent final deletion 

notice based on this notice of intent to 

delete. We will not institute a second 

comment period on this notice of intent 

to delete. Any parties interested in 

commenting must do so at this time. For 

additional information see the direct 

final notice of deletion located in the 

Rules section of this Federal Register. 

DATES: Comments concerning this Site 

must be received by March 6, 2008. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–HQ–

SFUND–1983–0002 Notice 4, by one of 

the following methods: 

http://www.regulations.gov (Follow 

the on-line instructions for submitting 

comments) 

E-mail: walters.donn@epa.gov. 

Fax: 214–665–6660. 

Mail: Donn Walters, Community 

Involvement, U.S. EPA Region 6 (6SF–

TS), 1445 Ross Avenue, Dallas, TX 

75202–2733, (214) 665–6483 or 1–800–

533–3508. 

Instructions: Direct your comments to 

Docket ID No. EPA–HQ–SFUND–1983–

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copy. Publicly available docket 

materials are available either 

electronically at http:// 

www.regulations.gov or in hard copy at 

the information repositories. 

FOR FURTHER INFORMATION CONTACT: 

Shawn Ghose M.S., P.E., Remedial 

Project Manager (RPM), U.S. EPA 

Region 6 (6SF–RA), 1445 Ross Avenue, 

Dallas, TX 75202–2733, 

ghose.shawn@epa.gov (214) 665–6782 

or 800–533–3508. 

SUPPLEMENTARY INFORMATION: For 

additional information see the Direct 

Final Notice of Deletion located in the 

‘‘Rules’’ section of this Federal Register. 

Information Repositories: Repositories 

have been established to provide 

detailed information concerning this 

decision at the following locations: U.S. 

EPA Region 6, 1445 Ross Avenue, Suite 

700, Dallas, Texas 75202–2733, (214) 

665–6617, by appointment only Monday 

through Friday 9 a.m. to 12 p.m. and 1 

p.m. to 4 p.m.; Fort Smith Public 

Library, 3201 Rogers Avenue, Ft. Smith, 

AR 72903, (479) 783–0229, Monday 

through Thursday, 9 a.m. to 9 p.m., 9 

a.m. to 6 p.m. Friday, 10 a.m. to 5 p.m. 

Saturday and 1 p.m. to 5 p.m. Sunday; 

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Quality (ADEQ), 5301 Northshore Drive, 

North Little Rock, Arkansas 72118, (501) 

682–0744, Monday through Friday 8 

a.m. to 4:30 p.m. 

List of Subjects in 40 CFR Part 300 

Environmental protection, Air 

pollution control, Chemicals, Hazardous 

waste, Hazardous substances, 

Intergovernmental relations, Penalties, 

Reporting and recordkeeping 

requirements, Superfund, Water 

pollution control, Water supply. 

Authority: 33 U.S.C. 1321(c)(2); 42 U.S.C. 

9601–9657; E.O. 12777, 56 FR 54757, 3 CFR, 

1991 Comp., p. 351; E.O. 12580, 52 FR 2923; 

3 CFR, 1987 Comp., p. 193. 

Dated: September 28, 2007. 

Richard E. Greene, 

Regional Administrator, EPA Region 6. 

Editorial Note: This document was 

received at the Office of the Federal Register 

on January 30, 2008. 

[FR Doc. E8–1963 Filed 2–4–08; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[FWS–R6–ES–2008–0013; 1111 FY07 MO–

B2] 

Endangered and Threatened Wildlife 

and Plants; 12-Month Finding on a 

Petition To List the Gunnison’s Prairie 

Dog as Threatened or Endangered 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Notice of a 12-month petition 

finding. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce our 

12-month finding on a petition to list 

the Gunnison’s prairie dog (Cynomys 

gunnisoni) as an endangered or 

threatened species under the 

Endangered Species Act of 1973, as 

amended (Act). After a thorough review 

of all available scientific and 

commercial information, we find that 

the species is not threatened or 

endangered throughout all of its range, 

but that the portion of the current range 

of the species located in central and 

south-central Colorado and northcentral New Mexico (the northeastern 

portion of the range) represents a 

significant portion of the range where 

the Gunnison’s prairie dog is warranted 

for listing under the Act. Currently, 

listing is precluded by higher priority 

actions to amend the Lists of 

Endangered and Threatened Wildlife 

and Plants. We have assigned a listing 

priority number (LPN) of 2 to this 

species, because threats have a high 

magnitude, and are imminent. We will 

develop a proposed rule to list the 

Gunnison’s prairie dog in the 

northeastern (montane) portion of its 

range as our priorities allow. 

DATES: This finding was made on 

February 5, 2008. 

ADDRESSES: This finding is available on 

the Internet at http:// 

www.regulations.gov and http:// 

www.fws.gov/mountain-prairie/species/ 

mammals/gunnisonprairiedog. 

Supporting documentation we used to 

prepare this finding is available for 

public inspection, by appointment, 

during normal business hours at the 

U.S. Fish and Wildlife Service, Western 

Colorado Field Office, 764 Horizon 

Drive, Building B, Grand Junction, CO 

81506–3946; telephone (970) 243–2778; 

facsimile (970) 245–6933. Please submit 

any new information, materials, 

comments, or questions concerning this 

finding to the above address. 


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FOR FURTHER INFORMATION CONTACT: Al 

Pfister, Field Supervisor, U.S. Fish and 

Wildlife Service, Western Colorado 

Field Office (see ADDRESSES). If you use 

a telecommunications device for the 

deaf (TDD), call the Federal Information 

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

SUPPLEMENTARY INFORMATION: 

Background 

Section 4(b)(3)(B) of the Act (16 

U.S.C. 1531 et seq.), requires that, for 

any petition containing substantial 

scientific and commercial information 

that listing may be warranted, we make 

a finding within 12 months of the date 

of receipt of the petition on whether the 

petitioned action is—(a) not warranted, 

(b) warranted, or (c) warranted, but that 

immediate proposal of a regulation 

implementing the petitioned action is 

precluded by other pending proposals to 

determine whether species are 

threatened or endangered, and whether 

expeditious progress is being made to 

add or remove qualified species from 

the Lists of Endangered and Threatened 

Wildlife and Plants. Section 4(b)(3)(C) of 

the Act requires that we treat a petition 

for which the requested action is found 

to be warranted but precluded as though 

resubmitted on the date of such finding; 

that is, requiring a subsequent finding to 

be made within 12 months. We must 

publish these 12-month findings in the 

Federal Register. 

Previous Federal Actions 

On February 23, 2004, we received a 

petition from Forest Guardians and 73 

other organizations and individuals 

requesting that the Gunnison’s prairie 

dog (found in Arizona, Colorado, New 

Mexico, and Utah) be listed as 

threatened or endangered. 

On July 29, 2004, we received a 60- 

day notice of intent to sue for failure to 

complete a finding. On December 7, 

2004, an amended complaint for failure 

to complete a finding for this and other 

species was filed. We reached a 

settlement agreement with the plaintiffs, 

and on February 7, 2006, we published 

a 90-day finding in the Federal Register 

(71 FR 6241) determining that the 

petition did not present substantial 

scientific information indicating that 

listing the Gunnison’s prairie dog 

species may be warranted. 

On August 17, 2006, Forest Guardians 

and eight other organizations and 

individuals provided written notice of 

their intent to sue regarding the 

determination in the 90-day finding. On 

December 13, 2006, the plaintiffs filed a 

complaint challenging the finding. On 

June 29, 2007, we reached a settlement 

agreement with the plaintiffs for 

submittal to the Federal Register of a 

12-month finding by February 1, 2008. 

The court adopted the terms and 

conditions of the agreement on July 2, 

2007. 

On August 28, 2007, we published a 

notice initiating the 12-month finding 

and opening a 60-day public comment 

period on the Gunnison’s prairie dog (72 

FR 49245). 

Species Information 

A description of the Gunnison’s 

prairie dog is included in the 90-day 

petition finding (71 FR 6241; February 

7, 2006) and in a concise review of the 

published information by Underwood 

(2007, pp. 6–13). In addition, we used 

data in the Western Association of Fish 

and Wildlife Agencies’ (WAFWA) 

Gunnison’s Prairie Dog Conservation 

Assessment (Seglund et al. 2005) to 

complete much of our analysis in this 

finding. 

The Gunnison’s prairie dog has 

sometimes been divided into two 

subspecies: Cynomys gunnisoni 

gunnisoni and C. g. zuniensis (Hollister 

1916, p. 29). We currently regard the 

Gunnison’s prairie dog as a single 

species because the most recent 

published analyses (Goodwin 1995, pp. 

100, 101, 110; Pizzimenti 1975, pp. 11, 

15, 63) do not support subspecies 

designation. Unpublished research 

(Hafner 2004, p. 6; Hafner et al. 2005, 

p. 2) indicates that the distribution of 

mitochondrial DNA (deoxyribonucleic 

acid) haplotype lineages supports past 

geographic isolation, followed by 

limited mixing in regions coincident 

with the recognized borders of the two 

purported subspecies. Although this 

analysis will likely be substantiated 

through additional research, it is still 

preliminary and needs to be verified 

before we can use it as evidence for 

subspecies designation. For the same 

reasons, although Gunnison’s prairie 

dogs in montane habitat may be 

‘‘markedly separate’’ from those in 

prairie habitat, we are not proposing 

listing the montane prairie dogs as a 

distinct population segment (DPS) 

under our Policy Regarding the 

Recognition of Distinct Vertebrate 

Population Segments Under the 

Endangered Species Act (61 FR 4722; 

February 7, 1996). We anticipate that 

future funding may become available for 

genetic, taxonomic, and range research 

to determine whether subspecies or DPS 

status is valid. 

Gunnison’s prairie dogs are a colonial 

species, historically occurring in large 

colonies over large areas. Colonial 

behavior offers an effective defense 

mechanism by aiding in the detection of 

predators, but it also can play an 

important role in the transmission of 

disease (Antolin et al. 2002, p. 19; 

Biggins and Kosoy 2001, p. 911). 

Complexes of Gunnison’s prairie dog 

colonies (metapopulations) expand or 

contract over time depending upon 

various natural factors (such as 

reproduction, food availability, and 

disease) and human-caused factors 

(such as chemical control and shooting). 

To substantially augment depleted 

populations or replace populations 

without human intervention, a 

metapopulation structure is required 

across the landscape so that migration 

between colonies is possible (Gilpin and 

Soule 1986, p. 24; Clark et al. 1982, pp. 

574–575; Lomolino and Smith 2001, p. 

938). 

Habitat 

Gunnison’s prairie dog habitat 

includes level to gently sloping 

grasslands and semi-desert and montane 

shrublands, at elevations from 6,000 to 

12,000 feet (1,830 to 3,660 meters) 

(Bailey 1932, p. 125; Findley et al. 1975, 

p. 133; Fitzgerald et al. 1994, p. 183; 

Pizzimenti and Hoffman 1973, p. 1; 

Wagner and Drickamer 2002, p. 4). 

Grasses are the most important food 

item, with forbs, sedges, and shrubs also 

occasionally used (Pizzimenti and 

Hoffman 1973, p. 3; Shalaway and 

Slobodchikoff 1988, p. 840). 

Gunnison’s prairie dog range can be 

considered to occur in two separate 

range portions—higher elevations in the 

northeast part of the range and lower 

elevations elsewhere (Bailey 1932, pp. 

125–127; Pizzimenti and Hoffman 1973, 

pp. 1–2; Hall 1981, p. 7; Knowles 2002, 

p. 4). We refer to these areas as montane 

and prairie, respectively, throughout the 

document to differentiate them; 

however, we recognize that these terms 

are an oversimplification of the actual 

habitats present, and describe them in 

more detail below. 

In Figure 1, we provide a map 

illustrating the division of the general 

range of the species into the 

northeastern (montane) and 

southwestern (prairie) portions. The 

outer boundary in Figure 1 is referenced 

from maps depicting the species’ gross 

range (Hollister 1916, p. 24; Pizzimenti 

and Hoffman 1973, p. 2; Pizzimenti 

1975, p. 4; Hall 1981, p. 415; Knowles 

2002, p. 6), and from maps of the 

species’ range in Arizona (Hoffmeister 

1986, p. 194), Colorado (Armstrong 

1972, p. 139; Fitzgerald et al. 1994, p. 

185), New Mexico (Findley et al. 1975, 

p. 133), and Utah (Durrant 1952, p. 106). 

An approximate boundary dividing the 

montane and prairie range portions was 

established from several maps that 

recognize discrete range portions for 

each of the two purported subspecies, 


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Cynomys gunnisoni gunnisoni and C. g. 

zuniensis (Hollister 1916, p. 24; 

Armstrong 1972, p. 139; Pizzimenti and 

Hoffman 1973, p. 2; Pizzimenti 1975, p. 

4; Hall 1981). Maps that depict the 

geographic variation in Gunnison’s 

prairie dog mitochondrial DNA in 

southern Colorado and northern New 

Mexico (Hafner 2004, p. 6; Hafner et al. 

2005, p. 2) were used to improve the 

resolution of the montane and prairie 

boundary in this region, as these maps 

provide a boundary based on genetic 

differences between Gunnison’s prairie 

dogs in the two range portions. Lastly, 

we used topographic maps to adjust the 

boundary on a finer scale along the 

mountain ranges and ridges of southern 

Colorado and northern New Mexico, 

because geography partly separates the 

Gunnison’s prairie dog populations and 

allows limited overlap between the two 

range portions (Knowles 2002, p. 3; 

Hafner et al. 2005, p. 1). 

In summary, the maps we used to 

delineate the montane and prairie range 

portions vary in their age, projection, 

scale, and accuracy, and depict 

boundaries based on geography, 

morphological traits of Gunnison’s 

prairie dog populations, and genetic 

characteristics from Hafner’s work 

(Hafner 2004, p. 6; Hafner et al. 2005, 

p. 2). They contribute to the best 

available information used to establish 

the montane and prairie portions of the 

species’ range for further analysis. 

BILLING CODE 4310–55–P 


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Montane Habitat 

The northeastern range (central and 

south-central Colorado, and northcentral New Mexico) consists primarily 

of higher elevation, cooler and more 

mesic plateaus, benches, and 

intermountain valleys. We call this 

portion ‘‘montane’’ for ease of reference, 

and it comprises approximately 40 

percent of the total potential habitat 

within the current range. Gunnison’s 

prairie dogs occupy grass-shrub areas in 

low valleys and mountain meadows 

within this habitat (Seglund et al. 2005, 

p. 12). The Gunnison’s prairie dogs in 

this portion of the range are limited by 

pronounced physiographic barriers 

(Pizzimenti and Hoffman 1973, p. 1), 

including the Uncompahgre Plateau and 

San Juan mountains in Colorado and 

Utah, and the Sangre de Cristo, San 

Juan, and Jemez mountain ranges in 

New Mexico. 

Prairie Habitat 

The southwestern range (southeastern 

Utah, southwestern Colorado, 

northwestern New Mexico, and 

northeastern Arizona) consists primarily 

of lower elevation, warmer and more 

xeric plains and plateaus (Bailey 1932, 

pp. 125–127; Pizzimenti and Hoffman 

1973, pp. 1–2; Hall 1981, p. 7; Knowles 

2002, p. 4). We call this portion 

‘‘prairie’’ for ease of reference, and it 

comprises approximately 60 percent of 

total potential habitat within the current 

range. Gunnison’s prairie dogs occupy 

shortgrass and mid-grass prairies within 

this habitat (Seglund et al. 2005, p. 12). 

Distribution, Abundance, and Trends 

The current distribution of the species 

includes northeastern Arizona; central, 

south-central, and southwestern 

Colorado; north-central and 

northwestern New Mexico; and extreme 

southeastern Utah (Bailey 1932, pp. 

125–127; Pizzimenti and Hoffman 1973, 

pp. 1–2; Hall 1981, p. 7; Knowles 2002, 

p. 4) (see Figure 1 above). Limited 

overlap occurs in the ranges of 

Gunnison’s prairie dogs and black-tailed 

prairie dogs (Cynomys ludovicianus) in 

New Mexico (Goodwin 1995, p. 101; 

Sager 1996, p. 1), and Gunnison’s 

prairie dogs and white-tailed prairie 

dogs (Cynomys leucurus) in Colorado 

(Knowles 2002, p. 5), but we have no 

evidence that interbreeding is occurring. 

Currently, 27 percent of potential 

Gunnison’s prairie dog habitat occurs in 

Arizona, 25 percent in Colorado, 45 

percent in New Mexico, and 3 percent 

in Utah (Seglund et al. 2005, p. 83). We 

used the data in Seglund et al. (2005, 

pp. 82, 85–87) to calculate that 

approximately 22 percent of the 

potential habitat occurs on private 

lands, 12 percent on State lands, 17 

percent on Federal lands, and 49 

percent on Tribal lands/Bureau of 

Indian Affairs (BIA). The Tribal lands 

habitat occurs mostly in Arizona and 

New Mexico; a large amount of potential 

habitat is on Navajo lands (Cole, p. 1). 

Most estimates of prairie dog 

populations in the available literature 

are expressed in terms of area (acres (ac) 

or hectares (ha)) of occupied habitat 

rather than in numbers of individuals, 

most likely because counting 

individuals is feasible only for small 

areas (Biggins et al. 2006, p. 94). Also, 

the number of animals present in a 

locality has been observed to vary with 

habitat, season, colony age, 

precipitation, forage, predation, disease, 

chemical control, shooting, and other 

factors (Knowles 2002, pp. 7–8); density 

of individuals typically ranges from 2 to 

23 per ac (5 to 57 per ha) (Fitzgerald et 

al. 1994, p. 184). Most prairie dog 

surveys do not result in a density 

estimate because of the associated effort 

and cost. Estimates of Gunnison’s 

prairie dog occupied habitat provide 

one of the best available and most 

reasonable means of evaluating the 

status of the species across its range. 

Obtaining estimates of occupied area 

is itself time-consuming and costly. 

Ground or aerial mapping of colonies 

over a predicted habitat range of 23 

million ac (9.5 million ha) in 4 States 

would be required to determine a 

rangewide estimate of the area occupied 

by the Gunnison’s prairie dog (Seglund 

et al. 2005, pp. 17–19). Recent attempts 

at less expensive aerial surveys (for 

example, air photo interpretation) have 

been limited in their effectiveness when 

applied to Gunnison’s prairie dogs 

(Johnson et al. 2006, p. 3; Seglund et al. 

2005, pp. 23–24). Whether surveying is 

performed from the air or on the ground, 

it is often difficult to accurately and 

consistently discern colony boundaries 

(thus introducing error in the area 

measurements). Older studies did not 

benefit from technologies such as global 

positioning systems and geographic 

information systems (GIS) in mapping 

colonies. Accuracy suffers when studies 

are performed over the longer time 

intervals necessary to visit large range 

portions, because colony area, location, 

and persistence on the landscape often 

change relatively quickly (Wagner et al. 

2006, p. 335). 

In summary, we recognize that 

different methodologies were used at 

different times and in different locales 

to derive the various historical occupied 

area estimates we obtained for review. 

These estimates contribute to the best 

available information, and we consider 

them comparable for determining longterm population trends, while 

acknowledging potential error margins 

on the scale of an order of magnitude. 

Since our 90-day finding in 2006, all 

States within the range of the species 

have applied occupancy modeling 

methodology to investigate the habitat 

occupied by Gunnison’s prairie dogs. 

This is a newer technique that yields 

estimates of the percentage of random 

plots occupied across the habitat range 

under consideration (MacKenzie et al. 

2002, pp. 2248–2249; MacKenzie et al. 

2003, pp. 2200–2201). These estimates 

are statistically based and, therefore, are 

considered more objective (Andelt et al. 

2006, pp. 1–2; Colorado Division of 

Wildlife (CDOW) 2007, p. 19; WAFWA 

2007, p. 4). 

A drawback is that estimates of 

percent occupancy by Gunnison’s 

prairie dogs are not directly comparable 

to estimates of occupied acres 

(including most historic estimates), 

because when a random plot is visited, 

only detection or non-detection (not 

acres occupied) is recorded by the 

observers. If mapping is not performed 

during a site visit, no information about 

colony or complex size or location is 

obtained. 

The positive aspects of this method 

are statistical rigor, precision estimates, 

large-scale application in a single 

season, and trend analysis if performed 

over subsequent years. In addition, the 

results of individual surveys can be 

interpreted separately to assess prairie 

dog occupancy and document trends 

within in specific areas of concern. 

Although only a single year (2007) of 

occupancy modeling results are 

available (with the exception of 

Colorado data from 2005 and 2007), we 

used these estimates, along with 

estimates of occupied areas, to assess 

the status and trends of the Gunnison’s 

prairie dog in each of the four States. 

Historical Estimates of Abundance 

Historical estimates of Gunnison’s 

prairie dog occupied habitat in Arizona 

and New Mexico are available from 

Federal records of early poisoning 

efforts, such as by the Bureau of Land 

Management (BLM) and the U.S. Forest 

Service (USFS). In 1916, approximately 

6.6 million ac (2.7 million ha) of 

Gunnison’s prairie dog occupied habitat 

occurred in Arizona, and 11 million ac 

(4.4 million ha) occurred in New 

Mexico (Oakes 2000, pp. 169–171). In 

our 90-day finding in 2006 (71 FR 6241, 

February 7, 2006), we calculated 

historical estimates (circa 1916) for 

Colorado (6 million ac (2.4 million ha)) 

and Utah (700,000 ac (284,000 ha)) from 

prairie dog information in various 


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publications and reports, because data 

were not available for these States. By 

summation, based on the best available 

information, our rangewide estimate for 

historic (circa 1916) Gunnison’s prairie 

dog occupied habitat was approximately 

24 million ac (9.7 million ha). 

In 1961, an estimated 445,000 ac 

(180,000 ha) of habitat was occupied by 

Gunnison’s prairie dog in Arizona; 

116,000 ac (47,000 ha) in Colorado; 

355,000 ac (144,000 ha) in New Mexico; 

and 100,000 ac (41,000 ha) in Utah 

(Bureau of Sport Fisheries and Wildlife 

1961, pp. 1, 5). By summation, the 

rangewide estimate for Gunnison’s 

prairie dog occupied habitat in 1961 

was approximately 1 million ac 

(405,000 ha). These data suggest that, 

from 1916 to 1961, Gunnison’s prairie 

dog populations decreased by 

approximately 93 percent in Arizona, 98 

percent in Colorado, 97 percent in New 

Mexico, and 86 percent in Utah, or by 

approximately 95 percent rangewide. 

However, historic declines may not 

support a conclusive inference that 

current populations continue to decline. 

In summary, empirical data on acres 

occupied indicate that, between 1916 

and 1961, habitat occupied by the 

Gunnison’s prairie dog throughout its 

range declined from approximately 

24,000,000 ac (9,700,000 ha) to 

approximately 1,016,000 ac (406,400 

ha). 

Statewide Estimates of Abundance 

As indicated above, estimates of 

percent occupancy arrived at through 

recent occupancy modeling (presence or 

absence at a random plot) do not equate 

to acres occupied. The method currently 

used by States to assess the Gunnison’s 

prairie dog’s status, in conjunction with 

both historic and recent mapping 

efforts, provides empirical data on 

percent occupancy of potential habitat. 

This data is useful as a gross-scale 

comparison to historical estimates of 

acres occupied. Both types of data are 

valid and represent the best available 

science. 

Full occupancy of surveyed habitat 

would not directly equate to 100 percent 

of available habitat, but it would 

provide a gross approximation of 

occupancy at a larger geographic scale. 

For the purposes of interpreting the 

percent occupancy numbers in this 

document, current State survey efforts 

utilize a scale from 1 to 100, indicating 

the percentage of occupied cells 

surveyed. Because we do not have 

historical data on percent of habitat 

occupied or on occupancy rates, we use 

the current percentage of occupied 

habitat to compare between habitats that 

currently appear to have a functional 

metapopulation structure (prairie) and 

that do not (montane). For example, the 

following paragraphs illustrate that 

Gunnison’s prairie dog occupancy in 

plots sampled in montane habitat is 

estimated to be approximately 3.6 

percent as compared to approximately 

18.3 percent in plots sampled in prairie 

habitat in Colorado. Of the total 

montane habitat, approximately 85 

percent occurs in Colorado. 

Arizona 

In 2007, occupied habitat on nonTribal lands in Arizona comprised 

approximately 108,570 ac (40,500 ha) 

(Underwood 2007, p. 30). No 

comprehensive data are available from 

Tribal lands in Arizona, which include 

50 percent of the Statewide potential 

habitat. Therefore, the 2007 estimate for 

Arizona (Underwood 2007, p. 30) is 

likely substantially less than what 

actually exists. Due to a lack of any 

Tribal estimates since 1961, recent 

population trends on Tribal lands 

statewide are unknown, but may have 

increased over the 1961 estimate of 

435,419 ac (176,207 ha). We are 

unaware of any disproportionate 

adverse effects to the species on Tribal 

lands during this interval, and we 

assume that habitat trends may have 

followed a similar pattern as on nonTribal lands. All habitat within Arizona 

is considered prairie. 

Colorado 

The Colorado Department of 

Agriculture (CDA 1990, p. A–3) 

solicited questionnaire responses from 

farmers and ranchers from which they 

extrapolated a 1990 estimate of 

1,553,000 ac (621,200 ha) of occupied 

habitat for all 3 species of prairie dogs 

found in Colorado (Gunnison’s, whitetailed, and black-tailed). Based on 

species occurrence by county, Seglund 

et al. (2005, p. 26) estimated that 

438,876 ac (177,607 ha) were occupied 

by Gunnison’s prairie dogs. 

From 2002 to 2005, the Colorado 

Division of Wildlife (CDOW) 

interviewed field personnel from 

CDOW, the Service, the USFS, and the 

BLM regarding the habitat occupied by 

Gunnison’s prairie dogs in the State. 

Colonies were mapped on 1:50,000 scale 

U.S. Geological Survey county sheets 

and were designated as ‘‘active’’ (known 

to have prairie dogs inhabiting the 

colony within the last 3 years); 

‘‘inactive’’ (prairie dogs occurred in the 

area but have not been present in more 

than 3 years); or ‘‘unknown’’ (prairie 

dogs were known to occur historically, 

but current status was unknown). From 

this effort, CDOW estimated 182,237 ac 

(72,895 ha) of active colonies; 9,042 ac 

(3,617 ha) of inactive colonies; and 

171,970 ac (68,788 ha) of colonies in 

unknown status within Colorado 

(CDOW 2007, p. 3). These data suggest 

an increase over the historical 1961 

estimate of 115,650 ac (46,802 ha) of 

occupied habitat in Colorado. We have 

no way of estimating what percent of 

this difference may be due to different 

mapping techniques. We believe that 

the difference is mostly due to an actual 

increase in prairie dogs, likely within 

the prairie portion of the range, because 

data from the montane portion of the 

range indicate significantly reduced 

occupancy rates (see additional analysis 

below). We used area estimates from 

2002 to 2005 to compute a Statewide 

occupancy estimate of 2.1 percent 

(known active colony area divided by 

area of potential habitat) (CDOW 2007). 

However, the occupancy modeling 

studies performed in 2005 and 2007 in 

Colorado, including both prairie and 

montane portions of the range, yielded 

Statewide occupancy estimates of 7.5 

and 8.6 percent, respectively (Andelt et 

al. 2006, p. 15; CDOW 2007, p. 19), and 

these estimates are considered more 

reliable. 

Montane and Prairie Habitat in 

Colorado 

Within Colorado, CDOW has 

designated individual population areas 

to identify where Gunnison’s prairie 

dogs exist and where management 

activities should be focused. The 

montane portion of the species’ range in 

Colorado is composed of the Gunnison, 

San Luis Valley, South Park, and 

Southeast population areas. By using 

CDOW (2007, p. 28) estimates of 

potential habitat, we determined that 

the montane range portion in Colorado 

comprises about 80 percent (6.9 million 

of 8.5 million ac (2.8 million of 3.4 

million ha)) of the available Gunnison’s 

prairie dog habitat in the State. 

However, the montane range portion 

only contains about 40 percent (73,861 

of 182,237 ac (29,544 of 72,894 ha)) of 

the available Gunnison’s prairie dog 

habitat occupied in the State, based on 

our calculations using CDOW mapped 

area data (CDOW 2007, p. 3). 

The La Plata—Archuleta and 

Southwest population areas, in the 

prairie portion of Colorado’s Gunnison’s 

prairie dog habitat, comprise about 20 

percent of the Gunnison’s prairie dog 

habitat and contain about 60 percent of 

habitat occupied in the State (CDOW 

2007, pp. 3, 19). The higher proportion 

of occupied habitat in the smaller 

prairie portion of the State indicates that 

Gunnison’s prairie dogs are more 

abundant in the prairie habitat area. 


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The 2005 occupancy modeling studies 

also indicate a higher proportion of 

occupancy (16 percent) in the prairie 

portion of the range in Colorado, and a 

lower proportion of occupancy (3.2 

percent) in the montane portion of the 

species’ range in Colorado (Andelt et al. 

2006, p. 17; CDOW 2007, p. 19). When 

the study was repeated over the same 

plots in 2007, occupancy was again 

found to be higher (18.3 percent) in the 

prairie portion and lower (3.6 percent) 

in the montane range portion in 

Colorado (CDOW 2007, p. 19). 

New Mexico 

We have no current information on 

occupied habitat in New Mexico. The 

best available science is from 

Bodenchuck (1981 p. 1), who solicited 

questionnaire responses from 

agricultural producers in 1981. 

Respondents reported 107,574 ac 

(43,567 ha) of Gunnison’s prairie dog 

occupied habitat. Bodenchuck (1981, p. 

8) extrapolated a Statewide total of 

348,000 ac (141,000 ha) of occupied 

habitat for the species. Oakes (2000, p. 

216) questioned this extrapolation 

because of possibly faulty assumptions 

used to derive it. Knowles (2002, p. 22) 

estimated that 75,000 ac (30,000 ha) of 

occupied habitat existed in 1982. New 

Mexico Department of Game and Fish 

used Digital Orthophoto Quarter 

Quadrangles to estimate a minimum of 

9,108 ac (3,689 ha) of occupied habitat 

Statewide in 2004 (Seglund et al. 2005, 

p. 23). However, this method appears to 

be hampered by inaccurate detection of 

disturbances, time elapsed since 

photography, time elapsed since ground 

mapping, temporal changes in prairie 

dog towns, and other factors (Seglund et 

al. 2005, p. 33). While these estimates 

have limited accuracy, general use in 

assessing Statewide occupied habitat 

indicates that Gunnison’s prairie dogs 

appeared to be decreasing between 1961 

and 2004. 

Montane and Prairie Habitat in New 

Mexico 

New Mexico also includes both 

montane and prairie habitat. The 

montane habitat is geographically 

connected to the montane portion of the 

Gunnison’s prairie dog habitat in 

Colorado. It comprises about 17 percent 

of the Gunnison’s prairie dog habitat in 

New Mexico; we do not have accurate 

data on total acres in New Mexico, and 

therefore do not provide an acre 

estimate for the montane portion. We 

have no data on the percent occupancy 

in this habitat. 

The prairie habitat in New Mexico 

comprises about 83 percent of the 

habitat; we do not have accurate data on 

total acres in New Mexico, and therefore 

do not provide an acre estimate for the 

prairie portion. We have no data on the 

percent occupancy in this habitat. 

Utah 

The Utah Division of Wildlife 

Resources estimated that 22,000 ac 

(8,906 ha) of occupied Gunnison’s 

prairie dog habitat existed in Utah in 

1968 (Seglund et al. 2005, p. 35). 

Knowles (2002, p. 21) estimated a 

minimum of 3,678 ac (1,490 ha) of 

occupied habitat Statewide. The 

Statewide trend in occupied habitat 

appears to have decreased from 100,000 

ac (40,500 ha) in 1961 (Bureau of Sport 

Fisheries and Wildlife 1961, p. 5), to 

40,000 ac (16,000 ha) in 2007 (Lupis et 

al. 2007, p. 3). The Gunnison’s prairie 

dog occupancy in Utah was estimated to 

be 15.7 percent in 2007 (Lupis et al. 

2007, p. 3). We consider all Gunnison’s 

prairie dog habitat in Utah as prairie. 

Summary of Statewide Estimates of 

Abundance 

We have empirical data on 

Gunnison’s prairie dog occupancy that 

indicate a large decline in rangewide 

occupied acres. We also have recent 

empirical data that indicates percent 

occupancy within two separate portions 

of the range is significantly different. 

Data on acres occupied indicate that 

between 1916 and the present, habitat 

occupied by Gunnison’s prairie dogs 

throughout its range declined from 

approximately 24,000,000 ac (9,700,000 

ha) to between 340,000 and 500,000 ac 

(136,000—200,000 ha). This represents a 

rangewide decline of greater than 95 

percent. 

Summary of Factors Affecting the 

Species Rangewide 

Section 4 of the Act (16 U.S.C. 1533) 

and implementing regulations at 50 CFR 

424, set forth procedures for adding 

species to the Federal Lists of 

Endangered and Threatened Wildlife 

and Plants. In making this finding, we 

summarize below information regarding 

the status and threats to the Gunnison’s 

prairie dog in relation to the five factors 

provided in section 4(a)(1) of the Act. 

In making this 12-month finding, we 

have considered all scientific and 

commercial information received or 

acquired between the time of the initial 

petition (February 23, 2004) and the end 

of the most recent public comment 

period (October 29, 2007), and 

additional scientific information from 

ongoing species surveys and studies as 

they became available. 

Under section (4) of the Act, we may 

determine a species to be endangered or 

threatened on the basis of any of the 

following five factors: (A) Present or 

threatened destruction, modification, or 

curtailment of habitat or range; (B) 

overutilization for commercial, 

recreational, scientific, or educational 

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

inadequacy of existing regulatory 

mechanisms; or (E) other natural or 

manmade factors affecting its continued 

existence. We evaluated whether threats 

to the Gunnison’s prairie dog may affect 

its survival. Our evaluation of threats, 

based on information provided in the 

petition, available in our files, and 

available in published and unpublished 

studies and reports, is presented below. 

A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of its Habitat or Range 

Agricultural land conversions 

historically had a significant impact on 

Gunnison’s prairie dog habitat (Knowles 

2002, p. 12). Gunnison’s prairie dogs 

have been displaced from some of the 

more productive valley bottomlands in 

Colorado and New Mexico (Longhurst 

1944, p. 36). Agriculture currently 

impacts 2,063,930 ac (834,243 ha), or 

less than three percent, of the 

Gunnison’s prairie dog range (Seglund 

et al. 2005, p. 43). Seglund et al. (2005, 

p. 41) indicate agriculture is not a major 

rangewide threat because of the small 

percentage of the range affected, but also 

because agriculture provides highly 

productive forage in place of the native 

arid landscape. Current adverse impacts 

relate to secondary actions at a local 

scale, such as prairie dog control (for 

example, poisoning, shooting) in areas 

where prairie dogs occupy lands used 

for agriculture, particularly private 

lands. We assess shooting under Factor 

C, poisoning under Factor E, and both 

in Factor D. 

Urbanization also has caused habitat 

loss for Gunnison’s prairie dog. Seglund 

et al. (2005, p. 41) determined that 

urbanization affects 577,438 ac (233,681 

ha) within the range of the species (less 

than two percent of the range). 

However, it appears this analysis 

considered only the direct effects of 

habitat loss. Urbanization also exerts 

indirect effects (for example, poisoning 

and shooting of prairie dogs), extending 

a human ‘‘disturbance zone’’ outward 

from the actual development footprint. 

Lower-density suburban development 

occurring in the southern Rocky 

Mountains is scattered and results in a 

fragmenting of habitats. In Colorado, 

urban development on the west slope of 

the Rocky Mountains (montane habitat) 

is occurring rapidly; 38 percent of 

Gunnison’s prairie dog range is 

predicted to be impacted by low urban 

development (less than 40 units per ac; 


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99 per ha), 6 percent by moderate 

development (40 to 80 units per ac; 99 

to 198 per ha), and 5 percent by high 

development (fewer than 80 units per 

ac) between 2000 and 2020 (CDOW 

2007, p. 28). We do not have 

information on the extent of 

development projected to occur in the 

other States within the species’ range 

(Utah, Arizona, and New Mexico). 

Potential threats to Gunnison’s prairie 

dog populations due to urban and 

suburban development exist, but have 

not been quantified, in the four cities of 

Santa Fe and Albuquerque, New 

Mexico; Flagstaff, Arizona; and 

Gunnison, Colorado (CDOW 2007, p. 4). 

In some areas, Gunnison’s prairie dogs 

threatened by urban development have 

been captured and relocated to 

preserves or other nearby habitats, 

mitigating effects to overall population 

numbers, but not to area of habitat. 

Although urban and suburban 

development exert adverse impacts on 

Gunnison’s prairie dog populations at a 

local scale, they likely affect less than 

three percent of the species’ range; low 

density development appears to be 

compatible with continued use by 

prairie dogs, due to the offsets provided 

by lawns and pastures that provide high 

quality forage (Seglund et al. 2005, p. 

41). 

Noxious weeds can increase in the 

presence of livestock overgrazing, and a 

relationship likely exists between 

overgrazing, Bromus tectorum (cheat 

grass) proliferation, and increased fire 

frequency and intensity (Seglund et al. 

2005, p. 43). However, we have no data 

that quantifies these factors or their 

correlation with effects to Gunnison’s 

prairie dog populations. The impact of 

overgrazing on prairie dog populations 

is contradictory. Some reports have 

noted that species density is positively 

correlated with the number of native 

plants (Slobodichikoff et al. 1988, p. 

406), and that grazing has decreased 

forage availability (Seglund et al. 2005, 

p. 42). Other reports have concluded 

that prairie dog density is positively 

correlated with an increase in grazing, 

which simulates the shortgrass-type of 

prairie environment preferred by prairie 

dogs (Fagerstone and Ramey 1996, p. 88; 

Marsh 1984, p. 203, Slobodchikoff et al. 

1988, p. 406). Considering the 

conflicting conclusions of published 

literature, and the lack of large-scale 

population decreases due to habitat 

alterations from livestock grazing, we 

find this is not a significant threat to the 

Gunnison’s prairie dog. 

Numerous land parcels within the 

Gunnison’s prairie dog range are leased 

for oil and gas development (Seglund et 

al. 2005, pp. 36, 42). However, no 

information is available that quantifies 

the amount of occupied habitat affected. 

In a study of white-tailed prairie dogs, 

Menkens and Anderson (1985, p. 13) 

concluded that any impact from seismic 

testing is negligible. However, we 

acknowledge that oil and gas 

development is rapidly occurring 

(Seglund et al. 2005, p. 44), and that this 

potential threat should be considered 

more closely when more accurate data 

are available. 

Road-related Gunnison’s prairie dog 

mortality exists in proximity to specific 

population areas. Roads may be 

increasing due to oil and gas 

development. However, no studies 

quantify road mortality of Gunnison’s 

prairie dogs. We have no data indicating 

that roads are currently threatening the 

species rangewide, and we conclude 

that prairie dog populations are able to 

recover from individual losses due to 

road mortality. 

Conservation principles indicate that 

smaller, more isolated populations are 

more vulnerable to extirpation (Barnes 

1993, p. 34; Cully 1993, p. 43; Fitzgerald 

1970, p. 78; Gilpin and Soule 1986, pp. 

30–31; Miller et al. 1994, p. 151; 

Mulhern and Knowles 1995, p. 21; 

Wilcox and Murphy 1985, p. 883; 

Wuerthner 1997, p. 464). Lomolino et 

al. (2003, p. 116) found that persistence 

of Gunnison’s prairie dog colonies 

increased significantly with larger 

colony size and decreased isolation. 

However, we found no studies or data 

that specifically assess the magnitude of 

the threats discussed under Factor A 

(agriculture land conversions, 

urbanization, grazing, roads, and oil and 

gas leasing) and resulting fragmentation 

throughout the range of Gunnison’s 

prairie dog habitat. 

Summary of Factor A 

After assessing the best available 

science on the magnitude and extent of 

the effects of agricultural land 

conversion, urbanization, grazing, roads, 

oil and gas development, and 

fragmentation of habitat, we find that 

the destruction, modification, and 

curtailment of Gunnison’s prairie dog’s 

habitat or range are not significant 

threats. Agriculture, urbanization, roads, 

and oil and gas development each 

currently affect a small percentage of 

Gunnison’s prairie dog habitat. Effects 

of livestock grazing, while widespread, 

have not resulted in measurable 

population declines. However, we need 

more information on the impacts of 

fragmentation and isolation with regard 

to persistence of prairie dog populations 

and on the magnitude of the potential 

threat posed by increasing oil and gas 

development. 

B. Overutilization for Commercial, 

Recreational, Scientific, or Educational 

Purposes 

Gunnison’s prairie dogs have been 

historically subjected to recreational 

shooting and shooting as a form of pest 

management on ranch and agricultural 

land; these practices continue under 

current State regulations (see Factor D. 

Inadequacy of Existing Regulatory 

Mechanisms). Prairie dogs are especially 

vulnerable to shooting due to their 

colonial behavior, which facilitates easy 

access to many individuals at once 

(Seglund et al. 2005, p. 48). Most field 

studies on the effects of shooting prairie 

dogs have been carried out on blacktailed prairie dogs, but we consider the 

results relevant to Gunnison’s prairie 

dogs (CDOW 2007, p. 41). Shooting 

effects include population reduction 

and alteration of behavior, such as 

decreased foraging rates and increased 

vigilance, which reduce individual 

prairie dog vigor and result in lower 

reproductive output (Knowles 1988, p. 

54; Reeve and Vosburgh in press, p. 5; 

Vosburgh 1996, pp. 32–33; Vosburgh 

and Irby 1998, p. 368; Pauli and Buskirk 

2007, pp. 1223–1224). 

Recreational shooting can reduce 

prairie dog population density at 

specific sites (Knowles 2002, p. 14; 

Miller et al. 1993, p. 91; Vosburgh 1996, 

pp. 13–14; Vosburgh and Irby 1998, pp. 

366–367). Local extirpation of colonies 

may have occurred in isolated 

circumstances in the past (Knowles 

1988, p. 54). However, increased 

population growth rates or recovery 

from very low numbers following 

shooting also have been reported 

(Knowles 1988, p. 54; Reeve and 

Vosburgh in press, p. 7). Recent studies 

of the effects of shooting on black-tailed 

prairie dogs appear to contradict the 

idea that populations quickly rebound 

from shooting. Reproductive output on 

colonies subjected to shooting decreased 

by 82 percent, while control colonies 

maintained a stable reproductive rate 

over the same period (Pauli and Buskirk 

2007, p. 1228). Therefore, black-tailed 

prairie dogs do not appear to rebound 

quickly from shooting. 

The International Union for the 

Conservation of Nature/Species Survival 

Commission (IUCN/SSC) Conservation 

Breeding Specialist Group evaluated the 

effects of shooting mortality on 

population viability of Gunnison’s 

prairie dogs (CDOW 2007, p. 124). 

Simulations were run with a shooting 

closure in place from March 1 through 

June 14 each year (approximating State 

closures) and without any closures. 

Having the closure in place resulted in 

positive population growth and 


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negligible risk of extinction, except in 

scenarios with the highest levels (20 

percent) of shooting-based mortality. 

Simulations run without the seasonal 

shooting closure in place suggest that 

when initial population sizes are 

smaller (less than 250 individuals) and 

shooting mortality is high (20 percent), 

a decrease in growth rate and an 

increase in population extinction risk 

exist (CDOW 2007, pp. 135–137). 

Colorado, Utah, and Arizona (outside 

Tribal lands) have implemented 

seasonal closures on prairie dog 

shooting. In Arizona and New Mexico, 

the Navajo Nation monitors this threat 

but currently implements no closures on 

shooting because it finds the level of 

shooting to be low on its lands (Cole 

2007, p. 4). 

Summary of Factor B 

We have determined that shooting 

continues to be a threat to the 

Gunnison’s prairie dog throughout all of 

its range and contributes to the decline 

of the species when combined with the 

effects of disease (see Factor C below). 

However, this threat is being monitored 

and managed in all States and the 

Navajo Nation, and modeling results 

suggest seasonal shooting closures 

implemented in Colorado and Arizona 

will likely reduce population-level 

losses. Therefore, we have determined 

that overutilization for commercial, 

recreational, scientific, or educational 

purposes is not a significant threat to 

the Gunnison’s prairie dog. 

C. Disease or Predation 

While prairie dogs are prey to 

numerous species, including coyotes, 

badgers, black-footed ferrets, and 

various raptor species, there is no 

information available to indicate that 

predation has an overall adverse effect 

on the species. Black-footed ferrets have 

been reintroduced into two locations in 

Arizona, including the Aubrey Valley, 

where Gunnison’s prairie dog 

populations appear to be stable. 

The Gunnison’s prairie dog is, 

however, affected by sylvatic plague, 

which occurs in regular outbreaks and 

causes population declines and 

extirpations. Plague is an exotic disease 

foreign to the evolutionary history of 

North American species (Barnes 1982, 

p. 238; Barnes 1993, p. 29; Biggins and 

Kosoy 2001, p. 907). This flea-borne 

disease, caused by infection with the 

bacterium Yersinia pestis, is shared by 

humans and other vertebrate animals. 

Rodents are the primary vertebrate hosts 

of Y. pestis, but other mammals can be 

infected. Y. pestis is transmitted to 

mammals by bites of infected fleas, 

direct contact with infected animals, 

and rarely by inhalation of infectious 

respiratory droplets from another 

animal (Gage et al. 1995, pp. 695–696). 

Plague was first observed in wild 

rodents (termed sylvatic plague) in 

North America near San Francisco, 

California, in 1908 and was detected in 

Gunnison’s prairie dogs in the 1930s 

(Eskey and Hass 1940, p. 6). Plague has 

subsequently spread so that it now 

encompasses the entire range of the 

species (Centers for Disease Control 

1998, p. 1; Cully 1989, p. 49; Girard et 

al. 2004, p. 8408). Therefore, it has only 

been present within the species’ range 

for approximately 70 years, allowing 

very little time for any resistance to 

evolve (Biggins and Kosoy 2001, p. 913). 

Once established in an area, plague 

becomes persistent and periodically 

erupts, with the potential to eventually 

extirpate or nearly extirpate entire 

colonies (Barnes 1982, p. 255; Barnes 

1993, p. 28; Cully 1989, p. 51; Cully et 

al. 1997, p. 711; Fitzgerald 1993, pp. 

52–53). The term ‘‘enzootic’’ describes 

plague existing at a less severe level, 

sometimes referred to as a 

‘‘maintenance’’ condition, that is 

present continuously throughout a 

species’ habitat; the term ‘‘epizootic’’

describes a severe plague outbreak or 

amplification transmission cycle (Gage 

et al. 1995, p. 696). 

Prairie dogs are highly susceptible to 

plague, and this susceptibility is 

thought to be a function of high 

population densities, abundant flea 

vectors, and uniformly low resistance 

(Biggins and Kosoy 2001, p. 913). 

Gunnison’s prairie dogs can experience 

mortality rates of greater than 99 percent 

during epizootics, and eradication of 

populations can occur within one active 

season (Lechleitner et al. 1962, pp. 190–

192; Lechleitner et al. 1968, p. 736; 

Rayor 1985, p. 194; Cully 1989, p. 49). 

Oral vaccination through 

consumption of vaccine-laden baits 

could reduce mortality from plague. 

Mencher et al. (2004, pp. 5504–5505) 

report protection against plague in 

black-tailed prairie dogs, elicited 

through voluntary consumption of a 

vaccine-laden bait in the laboratory. The 

vaccine has been shown to be safe in 

numerous animals including blackfooted ferrets, raccoons, skunks, 

bobcats, cats, dogs, and sheep. However, 

future field trials are required to test the 

efficacy on the Gunnison’s prairie dog. 

Recovery rates of Gunnison’s and 

Utah prairie dog colonies studied 2 

years post-epizootic found that 

Gunnison’s prairie dog colonies 

experienced 100 percent mortality and 

remained depopulated throughout the 

study due to the lack of available 

immigrants (Turner 2001, p. 14). Partial 

or complete recovery following 

population reductions due to plague 

have been reported for both white-tailed 

and black-tailed prairie dogs (Cully 

1993, pp. 40–41), but little to no 

recovery has been noted in montane 

Gunnison’s prairie dog colony die-offs, 

even after long periods of time 

(Capodice and Harrell 2003, pp. 5–7; 

Cully et al. 1997, p. 717; Lechleitner et 

al. 1968, p. 734). Possible long-term 

consequences of continued plague 

infection in Gunnison’s prairie dog 

populations may be: 

(1) local extirpation of colonies; 

(2) reduced colony size; 

(3) increased variance in local 

population sizes, and 

(4) increased inter-colony distances 

(CDOW 2007, p. 43). 

The factors that influence 

interspecific (between species) 

transmission of plague from mammalian 

or avian reservoirs (for example, 

coyotes, raptors, corvids) into prairie 

dog populations are unclear, but seem to 

be primarily through fleas that could 

increase in moister climates (Parmenter 

et al. 1999, p. 818; Rayor 1985, p. 195). 

However, interspecific transmission 

does not seem to be a significant factor 

creating plague epizootics. Plague is 

now considered enzootic throughout the 

range of the Gunnison’s prairie dog. 

The primary factor influencing plague 

enzootics in Gunnison’s prairie dogs is 

thought to be abundance of fleas within 

their own colonies. This appears to be 

correlated with seasonal moisture in 

specific habitat areas. Plague outbreaks 

may be triggered by climatic conditions, 

such as mild winters and moist springs 

(Parmenter et al. 1999, p. 818; Rayor 

1985, p. 195). Enscore et al. (2002, p. 

191) found a close relationship between 

human plague cases in the southwestern 

United States and high amounts of late 

spring (February to March) precipitation 

(time-lagged 1 and 2 years) and 

maximum daily summer temperature 

values in the moderately high range (85 

to 90 °F; 29 to 32 °C). 

Girard et al. (2004, p. 8408) 

postulated that when resistant hosts of 

plague encounter a susceptible species 

that is plague naı ̈ve and has a high 

population density, an epizootic occurs. 

During epizootic phases, declines in 

abundance of susceptible species like 

prairie dogs are observed (Hanson et al. 

2007, p. 790). The rapid dispersal of the 

pathogen through an area can be 

followed by an enzootic phase, a slower 

transmission cycle that disperses 

through the lower-density, more 

resistant hosts remaining from the first 

cycle. This establishes the disease in 

stable reservoirs for future emergence 


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(Girard et al. 2004, p. 8413; Gage and 

Kosoy 2005, pp. 506–509). 

Enzootic infection is generally 

considered characteristic of a stable 

rodent–flea infectious cycle where host 

rodents are relatively resistant to the 

disease. However, Hanson et al. (2007, 

p. 792) found that an unexpectedly high 

percentage of black-tailed prairie dog 

colonies in Montana tested positive for 

plague. They speculate that, under some 

conditions, black-tailed prairie dogs, 

rather than acting as resistant hosts, may 

serve as enzootic hosts or carriers of the 

pathogen. Plague antibody titers 

(concentrations in blood) have been 

found in small numbers of Gunnison’s 

prairie dogs in New Mexico, indicating 

individual exposure to plague and 

subsequent recovery (Cully et al. 1997, 

p. 717; Cully and Williams 2001, p. 

898). Plague appears to have had little 

effect on a Gunnison’s prairie dog 

population in Aubrey Valley, Arizona 

(Wagner and Van Andelt 2007, p. 2). 

However, little evidence of resistance to 

plague has been found in any species of 

prairie dog at this time. 

In conducting a Population Viability 

Analysis on Gunnison’s prairie dogs, the 

IUCN/SSC Conservation Breeding 

Specialist Group (CDOW 2007, p. 123) 

hypothesized that in an enzootic 

scenario, plague operates at a relatively 

low level each year, thereby increasing 

average annual rates of mortality above 

what would occur in a more benign 

non-enzootic scenario. 

Gunnison’s prairie dog populations 

are more susceptible to decline from 

plague than white-tailed prairie dog 

populations and are at least as, if not 

more, susceptible than black-tailed 

prairie dog populations (Antolin et al. 

2002, p. 14; Cully 1989, p. 51; Cully and 

Williams 2001, p. 899; Hubbard and 

Schmitt 1983, p. 51; Knowles 2002, p. 

13; Ruffner 1980, p. 20; Torres 1973, p. 

31; Turner 2001, p. iii). Gunnison’s 

prairie dogs commonly forage outside of 

their home territory, a characteristic that 

may play a significant role in the 

susceptibility of the species to plague. 

The Gunnison’s prairie dog may be 

more susceptible to plague than the 

black-tailed prairie dog because of the 

Gunnison’s less exclusive territorial 

behavior (many mix relatively freely 

throughout adjacent territories) and 

thereby contribute to the 

communicability of plague (Hoogland 

1999, p. 8). 

The Gunnison’s prairie dog is also 

likely more susceptible to plague than 

the white-tailed prairie dog because the 

Gunnison’s typically occurs at higher 

densities and is less widely dispersed 

on the landscape, allowing for more 

frequent transmission of the disease 

from one individual to another (Antolin 

et al. 2002, p. 19; Cully 1989, p. 49; 

Cully and Williams 2001, p. 901; Turner 

2001, p. 31). Biggins (2003, p. 6) 

speculated that if transmission rates for 

plague are at least partly dependent on 

host density, prairie dog populations on 

good quality sites may undergo both 

larger declines and more rapid 

recoveries than those on poor sites. 

Available literature is inconclusive 

regarding whether isolation or density 

of a colony affects the number and 

frequency of plague outbreaks. 

Lomolino et al. (2003, p. 118) and others 

(Cully and Williams 2001, p. 901; Miller 

et al. 1993, pp. 89–90) suggested that 

isolation and fragmentation may 

provide some protection to prairie dogs 

from plague by lessening the likelihood 

of disease transmission. However, this 

theory no longer applies when plague is 

enzootic throughout the range of 

Gunnison’s prairie dog (as it appears to 

be), in which case isolation of colonies 

reduces the chance of recolonization 

after extirpation (Wagner and Drickamer 

2002, p. 16; Lomolino and Smith 2001, 

pp. 942–943). In areas where 

Gunnison’s prairie dog colonies are 

located close to each other (less than 6 

miles (mi) (10 kilometers (km) apart), 

inter-colony dispersal of plague is likely 

through infected prairie dogs (Girard et 

al. 2004, p. 8412). For colonies 

separated by long distances or 

unsuitable habitats, infection may occur 

due to long-distance dispersal of plagueinfected fleas by domestic dogs, coyotes, 

raptors, or other predators and 

scavengers (Barnes 1993, p. 34), or 

plague may already persist as enzootic 

throughout Gunnison’s prairie dog 

range. 

The impacts of plague outbreaks, 

which lead to the loss of prairie dog 

colonies of all sizes (Roach et al. 2001, 

p. 956), are magnified by isolation of 

colonies. Colony growth after an 

epizootic is mainly the result of 

recolonization by inter-colony 

dispersers (Antolin et al. 2002, p. 17). 

Wagner et al. (2006, pp. 334–335) 

studied cycles of extirpation and 

recolonization in Gunnison’s prairie 

dogs in Arizona, including a large 

number of colonies over a large 

geographic area, and found a significant 

relationship between the persistence of 

colonies and the persistence of their 

nearest neighboring colony. Increased 

isolation decreases the likelihood of 

recolonization following a plague 

outbreak if the distance between the 

infected colony and the next nearest 

colony is beyond the dispersal 

capabilities of the species. For example, 

Lechleitner et al. (1962, pp. 195, 197) 

documented a 1959 plague outbreak in 

a Gunnison’s prairie dog colony in 

Colorado that killed all members of the 

colony. Prior to the outbreak, this 

colony had been continuously occupied 

for 20 years, despite several poisoning 

attempts. Two years after the plague 

outbreak, the colony still had not been 

recolonized, likely because it was 

isolated from other colonies by 8 mi (13 

km) (Lechleitner et al. 1962, p. 187). 

Research is underway on the efficacy 

of insecticides in protecting various 

prairie dog species from plague. Biggins 

and Godby (2005, p. 2) hypothesized 

that if enzootic plague is affecting 

populations of prairie dogs, an 

ambitious effort to remove the disease 

should result in increased survival rates 

of prairie dogs. Fleas in Utah prairie dog 

burrows were effectively controlled by 

annual treatments of the insecticide 

deltamethrin; fleas were reduced 96 to 

98 percent within one month of 

treatment (Biggins and Godby 2005, p. 

5). Studies of the effects of flea control 

on black-tailed and white-tailed prairie 

dogs have shown similar results 

(Biggins 2007). At this time, chemical 

dusting of individual prairie dog 

burrows is labor intensive and 

expensive. 

All recent, major Gunnison’s prairie 

dog colony declines documented in 

published literature have been 

attributed to plague epizootics. 

However, the magnitude of the plague 

threat appears to be different in the 

montane and prairie portions of the 

Gunnison’s prairie dog range. 

Population declines in prairie habitat 

are less dramatic than those in montane 

habitat; partial recovery or 

establishment of new colonies have 

been documented following plague in 

the prairie range portion, but are rare or 

absent following plague outbreaks in the 

montane range. 

We reviewed literature on the status 

of Gunnison’s prairie dog populations 

within the two portions of the range 

and, specifically, all published and 

unpublished literature on the effects of 

plague on prairie dogs. While some 

studies were not recent, summarizing 

them below provides background on the 

responses of Gunnison’s prairie dog 

populations to plague in each portion of 

the range. 

Effects of Plague in Montane Habitat 

Several well-studied colonies within 

the montane portion of the Gunnison’s 

prairie dog range have been documented 

as being extirpated, or nearly so, due to 

plague. The South Park, Colorado, 

population area included estimated 

occupied habitat of 915,000 ac (371,000 

ha) in 1945; 74,000 ac (30,000 ha) in 

1948; and 42 ac (17 ha) in 2002 (CDOW 


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2007). This decline was largely due to 

plague and affected a substantial portion 

of the species’ extant occupied habitat 

in Colorado (at least 15 percent). A 

plague event in Saguache County, 

Colorado, that progressed across seven 

colonies in 2 years left only scattered 

individuals surviving in two colonies 

(Lechleitner et al. 1968, p. 734). In 

Gunnison, Saguache, and Montrose 

Counties, Colorado, plague also was 

responsible for a decline from 15,569 ac 

(6,228 ha) of occupied habitat in 1980, 

to 770 ac (308 ha) in 2002 (note that 

Montrose County is in the Southwest 

population area in prairie habitat) 

(Capodice and Harrell 2003, pp. 5–7). A 

complete die-off of a colony due to 

plague in Chubbs Park, Chaffee County, 

Colorado, occurred in 1959 (Lechleitner 

et al. 1962, p. 185). In August 1958, the 

population was stable and healthy, but 

in 1959 an epizootic spread 2 mi (3 km) 

within 3 months; prairie dogs continued 

to be absent from the area in 1960 and 

1961, and we have no recent 

information on the existence of prairie 

dogs in that location. Plague resulted in 

the complete loss, over a 2-year period, 

of a colony in South Park, Colorado 

(Fitzgerald 1970, pp. 68–69). 

Approximately 1,000 to 1,500 

Gunnison’s prairie dogs were killed by 

an outbreak of plague in a 148-ac (60- 

ha) colony in Curecanti National 

Recreation Area near Gunnison, 

Colorado, in 1981 (Rayor 1985, p. 194). 

A few animals survived the disease and 

Gunnison’s prairie dogs were again 

abundant in the area in 1986 (Cully 

1989, p. 49). In 2002, 252 ac (102 ha) of 

habitat in the Recreation Area were 

occupied by Gunnison’s prairie dog 

colonies (Capodice and Harrell 2003, p. 

23), but the current estimate is 12 ac (4.8 

ha) (Childers 2007, p. 2). Colonies 

within the Recreation Area experienced 

six plague epidemics between 1971 and 

2007. Of the 9 historic Gunnison’s 

prairie dog colonies, 3 are currently 

active, and 2 act as source populations 

for the main prairie dog concentration 

area (Childers 2007, p. 1). If the source 

colonies die off due to plague, 

repopulation may not be possible 

because any other Gunnison’s prairie 

dog populations remaining will be 

separated by distance (more than 6 mi 

(10 km)) and impassable geographical 

features such as rivers and mountains 

(Lomolino et al. 2003, p. 116; 

Pizzimenti and Hoffman 1973, p. 1). 

Recently, plague has been implicated 

in the loss of several large colonies on 

BLM land within the Gunnison 

population area (CDOW 2007, p. 4). A 

large colony southeast of Gunnison, 

Colorado, that was very active in 2005, 

was totally devoid of prairie dogs in 

2006 and 2007. Four other large 

colonies in the same vicinity were 

active in 2006, but by 2007, no prairie 

dog activity was observed. Plague is the 

suspected cause of these extirpations, 

because of the complete elimination of 

the prairie dogs with no sign of 

poisoning (CDOW 2007, p. 4). 

Fitzgerald (1993, p. 52) expressed 

concern about the status of the 

Gunnison’s prairie dog in Colorado, 

indicating that plague had eliminated 

many populations, including almost all 

of the populations in South Park. He 

also suggested that populations 

appeared to be in poor condition in the 

San Luis Valley, and were extirpated 

from the extreme upper Arkansas River 

Valley, as well as Jefferson, Douglas, 

and Lake Counties. These areas 

comprise most of the Gunnison’s prairie 

dog montane habitat in Colorado. 

During 1984 through 1987, a plague 

event reduced the population of 

Gunnison’s prairie dogs in the Moreno 

Valley of New Mexico from more than 

100,000 individuals to between 250 and 

500, a decline of greater than 99 percent 

(Cully et al. 1997, pp. 708–711). 

Although the growth rate of the 

remaining population increased 

following the epizootic, another plague 

event swept through the area in 1988, 

and the population in July 1996 was 

still ‘‘a fraction’’ of what it had been in 

1984 (Cully et al. 1997, p. 718). 

Occupancy modeling performed in 

Colorado in 2005 indicated a lower 

proportion of occupancy in the montane 

portion of the species’ range within 

Colorado (3.2 percent) than in the 

prairie portion within Colorado (16.0 

percent) (Andelt et al. 2006, p. 17; 

CDOW 2007, p. 19). When the study 

was repeated over the same plots in 

2007, occupancy was again found to be 

lower (3.6 percent) in the montane range 

portion in Colorado than in the prairie 

portion (18.3 percent) (CDOW 2007, p. 

19). The only recent threat responsible 

for whole population declines and 

extirpations, as documented in the 

studies cited in this section, is plague. 

The frequency of plague epizootics 

appears to be high in montane habitat 

due to moister environmental 

conditions that are conducive to greater 

flea densities. The impact of plague 

epizootics in montane habitat is great 

because the small, isolated populations 

cannot recolonize. Within the South 

Park, Gunnison, and Southeast montane 

population areas in Colorado, no prairie 

dog complexes that approach a size 

considered sustainable exist, and only a 

few small complexes exist within the 

San Luis Valley population area (CDOW 

2007, pp. 1–17). Without a 

metapopulation structure, an overall 

decline in persistence takes place 

(Lomolino and Smith 2001, p. 942). 

The landscape status in the montane 

portion of Gunnison’s prairie dog range 

is characterized by fewer, smaller 

colonies that are isolated, and few to no 

complexes or metapopulation structure. 

Isolation of populations is related to the 

montane geography in this portion of 

the range. Gunnison’s prairie dogs 

occupy low valleys and mountain 

meadows within this habitat (Seglund et 

al. 2005, p. 12), likely because the short 

growing season at elevations higher than 

10,000 ft (3,048 m) limits forage (Andelt 

et al. 2006, p. 17). In addition, mountain 

topography minimizes the zone of 

contact between populations (Knowles 

2002, p. 3). At least four mountain 

ranges within the montane portion of 

the range act as barriers to Gunnison’s 

prairie dog dispersal (Pizzimenti and 

Hoffman 1973, p. 1). These factors make 

the prairie dogs in this habitat highly 

susceptible to plague-related declines, 

and we have no evidence of long-term 

recovery from plague in the montane 

habitat area. 

Effects of Plague in Prairie Habitat 

The Southwest and the La PlataArchuleta populations in Colorado are 

within the prairie portion of Gunnison 

prairie dog range. The Southwest 

population comprises the largest 

population of Gunnison’s prairie dogs in 

Colorado, with an estimated 88,267 ac 

(35,307 ha) of active colonies. Currently, 

prairie dogs can be found in nearly any 

habitat suitable for occupation, although 

densities are low to very low in native 

rangeland areas. Plague may be a 

problem in this area, because periodic 

die-offs not associated with poisoning or 

other control measures have been noted 

by local farmers and ranchers in the 

past. However, unlike populations in 

montane habitat within Colorado, these 

populations appear to rebound from 

periodic epizootics (CDOW 2007, p. 16). 

Populations in the La Plata-Archuleta 

population area appear to undergo 

plague outbreaks every 4 to 7 years, 

which may be limiting some 

populations (CDOW 2007, p. 7). 

Occupancy modeling in 2005 and 2007 

documented Gunnison’s prairie dog 

occupancy of 17.6 percent and 27.0 

percent, respectively, in the Southern 

Ute Reservation (part of the La PlataArchuleta population area), and 15.6 

percent and 16.3 percent in the 

Southwest area (CDOW 2007, p. 19). 

The persistence of these populations, 

while undergoing repeated plague 

outbreaks, is likely due to their 

proximity to other populations within 

the prairie portion of the species’ range 


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and immigration from those 

populations. 

In Arizona, from 1987 to 2001, an 

estimated 68 percent reduction in the 

number of active Gunnison’s prairie dog 

colonies occurred, primarily due to 

outbreaks of plague (Underwood 2007, 

p. 18; Wagner and Drickamer 2002, p. 

15). However, in the area known as the 

Coconino Plateau, the area occupied by 

Gunnison’s prairie dogs increased from 

2,126 ac (860 ha) in 1992 to 40,942 ac 

(16,569 ha) in 2007 (Van Pelt 2007, p. 

3), suggesting the species can withstand 

large plague epizootics through colony 

expansion or recolonization from nearby 

colonies. In addition, the Aubrey Valley 

Complex (in northwestern Arizona, the 

westernmost part of the species’ range) 

has remained stable since at least 1974, 

despite the presence of plague, and the 

size of this complex increased from 

approximately 30,000 ac (12,000 ha) in 

1997 (Underwood 2007, p. 23), to 

40,000 ac (16,800 ha) in 2005 (Van Pelt 

2005, p. 2), to 47,785 ac (19,338 ha) in 

2007 (Van Pelt 2007, p. 2). Gunnison’s 

prairie dogs at this site had significantly 

higher levels of antigens associated with 

disease-causing pathogens such as 

plague, the same immune response 

expected if the prairie dogs had been 

vaccinated against plague (Wagner and 

Van Andel 2007, p. 2). 

Of 293 colonies surveyed within 

Gunnison’s prairie dog range in Arizona 

outside of Tribal lands, 57 (19 percent) 

experienced die-offs during the 

summers of 2000 and 2001 (Wagner and 

Drickamer 2002, p. 13). Plague was 

confirmed as the causative agent for 15 

of these 57 colonies but is thought to be 

the likely cause for them all, because it 

is the only disease that causes outbreaks 

with high mortality in prairie dogs 

(Barnes 1993, p. 34; Wagner and 

Drickamer 2002, p. 13). During surveys, 

they also identified the approximate 

boundaries of two previous plague 

outbreaks (Wagner and Drickamer 2002, 

p. 14). 

An outbreak occurred over 

approximately 1,120 square mi (2,900 

square km) west of the town of Dilkon, 

Arizona, on the Navajo Indian 

Reservation. This outbreak probably 

occurred in 1995 or 1996 (Wagner and 

Drickamer 2004, p. 14). Previous 

surveys in the area documented 45 

colonies on 8,649 ac (3,500 ha). 

Reexamination of these colonies in 2000 

and 2001 showed that all but two 

colonies were inactive. At most of the 

inactive colonies, burrow entrances 

were completely closed, and only 

mounds indicated where they formerly 

occurred. 

An outbreak occurred east of the town 

of Seligman, Arizona, across 

approximately 425 square mi (1,100 

square km) around 1996. The Arizona 

Game and Fish Department conducted 

surveys in this area between 1990 and 

1994, and identified 47 active colonies 

that covered approximately 8,649 ac 

(3,500 ha). In 1996, die-offs were 

observed in this area, and the U.S. 

Centers for Disease Control and 

Prevention confirmed plague as the 

cause. Although prairie dog numbers 

were increasing again in 1998, surveys 

in 2001 indicated that only 11 of the 47 

colonies were active. Possibly another, 

undocumented, plague outbreak 

occurred in 1999 or 2000, again 

reducing the number of individuals 

(Underwood 2007, p. 19). Despite this 

persistent plague activity, Gunnison’s 

prairie dogs are becoming reestablished 

in some areas within the boundaries of 

the Seligman outbreak (Wagner and 

Drickamer 2002, pp. 14–15). This 

apparent resiliency is most likely due to 

immigration from other colonies in the 

prairie portion of the species’ range. 

Plague cycles have been observed in 

Gunnison’s prairie dogs in Utah, and 

populations have been known to die off 

and then recover (Lupis et al. 2007, p. 

32). Because plague testing has not been 

conducted on Gunnison’s prairie dogs 

in Utah, declines cannot definitively be 

attributed to the disease (Seglund et al. 

2005, p. 52). Plague is anticipated to be 

an ongoing threat to Gunnison’s prairie 

dog populations in Utah at both a 

localized, and a widespread, scale 

(Lupis et al. 2007, p. 32). The Utah 

Division of Wildlife Resources recently 

conducted point surveys and found that 

occupancy was 15.7 percent. Based on 

observed occupancy, they estimate that 

roughly 40,000 ac (16,000 ha) of 

southeastern Utah were inhabited by 

Gunnison’s prairie dogs in 2007. 

Of 65 Gunnison’s prairie dog colonies 

occupied prior to 1984 in west-central 

New Mexico, 32 (49 percent) were still 

occupied in 2005 (Luce 2005, p. 4). The 

active colonies were estimated to cover 

5,997 ac (2,399 ha) (Luce 2005, p. 5). 

The New Mexico Department of Game 

and Fish recently initiated occupancy 

modeling surveys similar to those used 

by CDOW and the Utah Division of 

Wildlife Resources; however, we 

currently have no data from that effort. 

Summary of Factor C 

The studies cited above document the 

serious impact that plague has on 

Gunnison’s prairie dogs. Although 

plague antibody titers have been found 

in a few individuals, periodic epizootic 

plague events generally kill more than 

99 percent of an affected population. 

Whether individual populations recover 

from these epizootics depends on two 

main factors: (1) The availability of 

other source populations to recolonize 

an area; and (2) the frequency of 

epizootic outbreaks, which can reduce 

population numbers more quickly than 

individual prairie dogs from 

neighboring colonies can recolonize. 

Populations in the more mesic 

montane areas of Gunnison’s prairie dog 

range appear to have been widely and 

severely affected by plague. This may be 

partly due to climatic conditions such 

as higher levels of spring moisture, 

which has been shown to increase flea 

numbers, and in turn, plague outbreaks. 

Isolation of prairie dog populations does 

not seem to protect them from the 

spread of plague, because it appears that 

plague exists with all parts of the range 

at some level, and can be spread by 

wider-ranging animals. The case studies 

cited in this section indicate that large 

populations have been repeatedly 

affected by plague and have shown no 

substantial recovery over long periods of 

time—decades in some cases. This has 

left smaller, more scattered populations 

throughout the montane range portion 

and a complete lack of metapopulation 

structure, with the result that areas 

affected by plague are less likely to be 

recolonized by nearby populations. 

While little information is currently 

available on prairie dog movement 

within this montane habitat, its 

geography (populations are located in 

valleys between mountainous areas) 

probably impedes the ability of prairie 

dogs to recolonize populations. Within 

this geographic area, CDOW found 

slightly more than 3 percent occupancy 

of surveyed plots. 

Although documented population 

declines due to plague outbreaks also 

occur in the more xeric prairie portions 

of Gunnison’s prairie dog range, 

evidence shows that many of these 

populations recover more rapidly from 

plague epizootics, probably due to the 

availability of nearby colonizers. This 

portion of the range has maintained a 

metapopulation structure that provides 

source populations for plague-affected 

populations. The largest population in 

Arizona, Aubrey Valley in the driest 

portion of the range, has been increasing 

in recent years and shows indications of 

exposure to plague without the 

devastating effects observed elsewhere. 

The CDOW data documents 

approximately 18 percent occupancy 

within prairie habitat in Colorado. 

Studies in Utah and west-central New 

Mexico indicate a historic decline in 

habitat occupancy of approximately 50 

percent (Wright 2007, p. 3; Luce 2005, 

p. 4), and a greater decline in Arizona 

(Wagner and Drickamer 2002, p. 11). 

While this is significant, it is far less 


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than the declines seen in the montane 

habitat area; in addition, 

metapopulation structure continues to 

exist, and at least one Gunnison’s 

prairie dog complex (Aubrey Valley, 

Arizona) is exhibiting some resistance to 

plague epizootics. 

The impacts of plague appear to be 

ongoing with moderate population-level 

effects when assessed across the entire 

range of the Gunnison’s prairie dog. 

Within the prairie portion of the range, 

plague has reduced the number of 

populations, and is reducing the size of 

populations, but has not decimated the 

existing metapopulation structure. 

Gunnison’s prairie dog colonies in 

prairie habitat exhibit rebound and 

recovery from plague epizootics in 

many population areas due to 

availability of animals from adjacent 

colonies. So far, plague has resulted in 

moderate effects to the species in the 

prairie portion of the range. 

Within the montane portion of the 

range, plague has significantly reduced 

the number and size of populations, 

resulting in high effects to the species. 

Populations within montane habitat 

have three distinct disadvantages in 

resisting the effects of plague: 

(1) A higher frequency of epizootics 

due to the moister montane climate that 

is conducive to higher abundance of 

fleas that spread plague; 

(2) smaller populations that cannot 

recover in numbers from plague 

epizootics; and 

(3) isolated populations and no 

metapopulation structure, due to 

reduced population sizes from past 

plague epizootics and montane 

geography, and therefore a significantly 

limited ability to recolonize. 

After assessing the best available 

science on the magnitude and extent of 

the effects of plague, we find that the 

impact of plague in the montane portion 

of the Gunnison’s prairie dog range is 

significant. However, plague does not 

rise to a level of being a significant 

threat to the Gunnison’s prairie dog 

throughout its range. 

D. Inadequacy of Existing Regulatory 

Mechanisms 

Local Laws and Regulations 

Approximately 22 percent of potential 

Gunnison’s prairie dog habitat occurs on 

private lands, and another 30 percent 

occurs on Tribal lands or lands managed 

by the Bureau of Indian Affairs (Seglund 

et al. 2005, p. 21). We are not aware of 

any city, or county ordinances that 

provide for protection or conservation of 

the Gunnison prairie dog or its habitat. 

We recognize that city, county, and 

Tribal ordinances that address issues 

such as agricultural lands, 

transportation, and zoning for various 

types of land use have the potential to 

influence the Gunnison’s prairie dog or 

its habitat; for example, zoning that 

protects open space might retain 

suitable habitat, and zoning that allows 

a housing development might destroy or 

fragment habitat. 

Colorado State Statute C.R.S. 30–28–

101 exempts parcels of land of 35 ac (14 

ha) or more per home from regulation, 

so county zoning laws in Colorado only 

restrict developments with housing 

densities greater than one house per 35 

ac (14 ha). This State statute allows 

some parcels to be exempt from county 

regulation and may negatively impact 

some prairie dogs. 

Tribal Laws and Regulations 

Approximately 49 percent of potential 

Gunnison’s prairie dog habitat occurs on 

Tribal lands (Seglund et al. 2005, p. 21). 

On the Navajo Nation, Gunnison’s 

prairie dog is classified as small game, 

and a hunting license is required to 

shoot them (Cole 2007, p. 4). In general, 

access and permission to hunt on Tribal 

lands are limited for non-Tribal 

members as a result of various trespass 

laws, but access by Tribal members is 

not limited. We are aware of no seasonal 

shooting closures in effect on Tribal 

land. Work on the Navajo Nation 

Gunnison’s Prairie Dog Management 

Plan, which will incorporate elements 

of the Arizona, New Mexico, and Utah 

State plans, is expected to begin 

immediately after finalization of the 

Gunnison’s prairie dog rangewide 

inventory (Cole 2007, p. 5). The Navajo 

Nation allows lethal and non-lethal 

removal of Gunnison’s prairie dogs for 

agricultural, human health, and safety 

purposes (Cole 2007, pp. 4, 5) 

We are not aware of any other Tribal 

ordinances that provide for protection 

or conservation of the Gunnison prairie 

dog or its habitat. We recognize that 

Tribal ordinances that address issues 

such as agricultural lands, 

transportation, and zoning for various 

types of land uses have the potential to 

influence the Gunnison’s prairie dog or 

its habitat; for example, zoning that 

protects open space might retain 

suitable habitat, and zoning that allows 

a housing development might destroy or 

fragment habitat. 

State Laws and Regulations 

Approximately 12 percent of 

Gunnison’s prairie dog potential habitat 

occurs on State and Federal lands 

(Seglund et al. 2005, pp. 82). 

Gunnison’s prairie dogs are considered 

a Species of Greatest Conservation Need 

in Arizona, a State Sensitive Species in 

Utah, and have no special conservation 

status in Colorado or New Mexico. All 

four States discuss the Gunnison’s 

prairie dog in Comprehensive Wildlife 

Conservation Strategies (Seglund et al. 

2005, p. 55) that confer no regulatory 

mechanisms, but assert that the species 

is at risk, declining, and deserving of 

special management consideration. 

In Arizona, all prairie dog species are 

classified as nongame mammals, and a 

hunting license is required to shoot 

them (Underwood 2007, p. 27). In 2001, 

the hunting season for Gunnison’s 

prairie dogs was changed from yearround to an April 1 to June 15 closure 

that applies to Federal, State, and 

private lands (Underwood 2007, p. 28). 

In Colorado, the Gunnison’s prairie 

dog is classified as a small game species, 

and take is allowed by rifle, handgun, 

shotgun, handheld bow, crossbow, 

pellet gun, slingshot, falconry, and 

toxicants (CDOW 2007, pp. 41–42). A 

small game license is required, with the 

exception of private landowners and 

their immediate family members or 

designees, who may take Gunnison’s 

prairie dogs causing damage on their 

lands. Shooting on public lands is not 

allowed between March 1 and June 14 

(no take is permitted in any season on 

national wildlife refuges) (CDOW 2007, 

pp. 41–42). During the open season, no 

bag or possession limits exist; however, 

contestants in shooting events may take 

no more than five prairie dogs per event 

(CDOW 2007, pp. 41–42). No seasonal 

shooting closures are in effect on private 

or Tribal lands. 

In New Mexico, Gunnison’s prairie 

dogs may be taken year-round without 

a permit by residents; non-residents are 

required to obtain a New Mexico 

hunting license to shoot prairie dogs 

within the State (Seglund et al. 2005, 

pp. 31, 32). 

In Utah, shooting of Gunnison’s 

prairie dogs is prohibited on public 

lands from April 1 to June 15, but they 

may be taken on private lands yearround; no license is required for 

shooting Gunnison’s prairie dogs, and 

no bag limit exists (Lupis et al. 2007, pp. 

18–19). 

Access and permission to hunt on 

private and Tribal lands are limited as 

a result of various trespass laws. All 

States that provide habitat for 

Gunnison’s prairie dogs allow their 

removal for agricultural, human health, 

and safety purposes (Seglund et al. 

2005, p. 46). 

The States within the range of the 

Gunnison’s prairie dog developed a 

Rangewide Conservation Strategy that 

provides guidance regarding specific 

activities to include in individual State 

plans for prairie dog conservation and 


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management (Seglund et al. 2005, p. 

55). All of the States with Gunnison’s 

prairie dog habitat are in the process of 

developing State Conservation Plans. 

The four plans are in different phases of 

development but are scheduled for 

completion by March 2008. The four 

States have agreed on a monitoring 

strategy to determine population trends 

of Gunnison’s prairie dog across their 

range (Van Pelt 2007, p. 2). 

Within Colorado, in the montane 

portion of the species’ range, CDOW has 

designated individual population areas 

to identify where Gunnison’s prairie 

dogs exist and where management 

activities should be focused. This 

portion of the species’ range is 

comprised of the Gunnison, San Luis 

Valley, South Park, and Southeast 

population areas. 

The Gunnison population area is 

approximately 68 percent Federal, and 2 

percent State, 30 percent private 

ownership (CDOW 2007, p. 2). The San 

Luis Valley population area is 

approximately 40 percent Federal, 6 

percent State, and 54 percent private 

ownership (CDOW 2007, p. 2). The 

South Park and Southeast population 

areas are 34 percent Federal, 7 percent 

State, and 59 percent private ownership. 

The large percentage of private lands, 

where minimal regulatory mechanisms 

exist, appears to compound the effects 

of shooting and poisoning in this 

montane portion of the species’ range 

that is already at lower occupancy than 

the prairie portion of the species, 

especially in conjunction with plague 

for which there are no regulatory or 

protective mechanisms. 

United States Federal Laws and 

Regulations 

Federal agencies are responsible for 

managing approximately 17 percent of 

Gunnison’s prairie dog habitat. The 

primary Federal agency managing 

Gunnison’s prairie dog habitat is BLM 

(12 percent); the USFS (4.3 percent), 

National Park Service (0.5 percent), 

Department of Defense (0.4 percent), 

and the Service (0.1 percent) also 

contribute to management of the 

species. 

Bureau of Land Management 

The Federal Land Policy and 

Management Act of 1976 (FLPMA) (43 

U.S.C. 1701 et seq.) is the primary 

Federal law governing most land uses 

on BLM lands. Section 102(a)(8) of 

FLPMA specifically recognizes wildlife 

and fish resources as being among the 

uses for which these lands are to be 

managed. BLM must consider the needs 

of wildlife, including general 

considerations of Gunnison’s prairie 

dogs, when conducting activities in 

their habitat. 

The Gunnison’s prairie dog is 

designated by BLM as a sensitive 

species in Utah only; therefore, they are 

not required to provide special 

protections and mitigation during 

project and activity planning in 

Arizona, Colorado, or New Mexico. 

BLM’s Resource Management Plans 

(RMPs) are the basis for all of its actions 

and authorizations involving BLMadministered lands and resources. They 

establish allowable resource uses; 

resource condition, goals and objectives 

to be attained; program constraints and 

general management practices needed to 

attain the goals and objectives; general 

implementation sequences; and 

intervals and standards for monitoring 

and evaluating the plan to determine its 

effectiveness and the need for 

amendment or revision (43 CFR 1601.0–

5(k)). 

RMPs provide a framework and 

programmatic guidance for site-specific 

activity plans. Site-specific plans 

address livestock grazing, oil and gas 

field development, travel management, 

wildlife habitat management, and other 

activities. Activity plan decisions 

normally require National 

Environmental Policy Act (NEPA) (42 

U.S.C. 4321 et seq.) analysis. 

The BLM has regulatory authority for 

oil and gas leasing and operating, as 

provided at 43 CFR 3100 et seq. BLM 

usually incorporates stipulations as a 

condition of issuing a lease. The BLM’s 

planning handbook has programspecific guidance for fluid minerals 

(which include oil and gas) that 

specifies that RMP decision-makers will 

consider restrictions on areas subject to 

leasing, including closures, and lease 

stipulations (BLM 2000, Appendix C, p. 

6). The handbook also specifies that all 

stipulations must have waiver, 

exception, or modification criteria 

documented in the plan, and indicates 

that the least restrictive constraint to 

meet the resource protection objective 

should be used (BLM 2000, Appendix C, 

p. 6). The BLM has regulatory authority 

to condition drilling permits to include 

prairie dog conservation stipulations 

(BLM 2004, pp. 3–60). Some oil and gas 

leases have a 0.12-mi (0.19-km) 

stipulation, which allows movement of 

the drilling area by that distance (BLM 

2004). We do not have data to evaluate 

the effectiveness of BLM’s program on 

prairie dog conservation. 

U.S. Forest Service 

The Gunnison prairie dog is a USFS 

Sensitive Species in New Mexico and 

Colorado, where it is considered to be 

imperiled (USFS 2007, line 135) based 

on NatureServe rankings (USFS 2004, 

pp. 60, 64). Management of Federal 

activities on National Forest System 

lands is guided principally by the 

National Forest Management Act 

(NFMA) (16 U.S.C. 1600–1614, August 

17, 1974, as amended). The NFMA 

specifies that all national forests and 

grasslands must have a Land and 

Resource Management Plan (LRMP) (16 

U.S.C. 1600) to guide and set standards 

for natural resource management 

activities. The NFMA requires the USFS 

to incorporate standards and guidelines 

into LRMPs (16 U.S.C. 1600). This has 

historically been done through a NEPA 

process. Provisions to manage plant and 

animal communities for diversity, based 

on the suitability and capability of a 

specific land area, are developed in 

order to meet overall multiple-use 

objectives. 

The 1982 NFMA implementing 

regulation for land and resource 

management planning (1982 rule, 36 

CFR 219), under which all existing 

forest plans were prepared, requires the 

USFS to manage habitat to maintain 

viable populations of existing native 

vertebrate species on National Forest 

System lands (1982 rule, 36 CFR 

219.19). A new USFS planning 

regulation was promulgated on January 

5, 2005 (70 FR 1023), and supersedes 

the 1982 rule. Plans developed under 

the new regulation are to be more 

strategic and less prescriptive in nature 

than those developed under the 1982 

planning rule. For example, previous 

plans might have included a buffer for 

activities near the nest sites of birds 

sensitive to disturbance. Under the new 

regulation, a desired condition 

description and guidelines will be 

provided, rather than a set of 

prescriptive standards that apply to 

projects. Planning, and decisions for 

projects and activities, will address sitespecific conditions and identify 

appropriate conservation measures to 

take for each project or activity. 

However, this planning regulation was 

struck down by the U.S. District Court 

for the Northern District of California on 

March 30, 2007, and is not currently in 

use by the USFS. We are uncertain 

which direction the USFS is 

implementing for the Gunnison’s prairie 

dog, or whether Gunnison’s prairie dog 

habitat objectives and conservation 

measures have been incorporated into 

grazing allotment plans or LRMPs. 

Summary of Factor D 

On a basis on a review of the available 

existing information, it does not appear 

that the inadequacy of existing 

regulatory mechanisms is a significant 

threat to the Gunnison’s prairie dog. 


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However, the percentage of private 

lands within the montane portion of the 

species’ range results in a paucity of 

regulatory mechanisms that potentially 

result in increased shooting and 

poisoning, which exacerbate the effects 

of plague in that portion of its range. At 

this time, no regulatory mechanisms 

exist to mitigate the effects of plague. 

E. Other Natural or Manmade Factors 

Poisoning of Gunnison’s prairie dogs 

has historically been documented 

throughout the species’ range, but no 

evidence indicates that poisoning 

currently occurs on a broad scale. The 

WAFWA Gunnison’s Prairie Dog 

Conservation Assessment summarizes 

poisoning campaigns in the four States 

(Seglund et al. 2005, pp. 56–57). From 

1914 to 1964, 2,310,203 ac (934,906 ha) 

of Gunnison’s prairie dog habitat were 

poisoned in Arizona; 23,178,959 ac 

(9,380,192 ha) of habitat were poisoned 

in Colorado; 20,501,301 ac (8,296,582 

ha) of habitat were poisoned in New 

Mexico; and 2,715,930 ac (1,099,098 ha) 

of habitat were poisoned in Utah. On 

public lands, poisoning efforts have led 

to a reduction in occupied habitat, 

extirpation from local areas, 

fragmentation, and isolation of colonies. 

Poisoning in all States became less 

common after Federal regulation of 

pesticides was enacted. State and 

Federal agencies are rarely involved in 

control efforts unless human health and 

safety are at risk (Seglund et al. 2005, p. 

57). Individual landowners may still 

control prairie dogs on their private 

property. 

No studies indicate that drought has 

a negative rangewide effect on 

Gunnison’s prairie dogs. Impacts to the 

Gunnison’s prairie dog under predicted 

future climate change are unclear. A 

trend of warming in the mountains of 

western North America is expected to 

decrease snowpack, hasten spring 

runoff, and reduce summer flows (IPCC 

2007, p. 10). Increased summer heat 

may increase the frequency and 

intensity of wildfires (IPCC 2007, p. 14). 

Given the different climate variables 

between the montane and prairie 

geographic areas, populations in prairie 

habitat may show evidence of effects 

from climate change earlier than those 

in montane habitat. While it appears 

reasonable to assume that Gunnison’s 

prairie dogs may be affected, we lack 

sufficient certainty on knowing how 

climate change will affect the species, or 

the potential changes to the level of 

threat posed by plague. The most recent 

literature on climate change includes 

predictions of hydrologic changes, 

higher temperatures, and expansion of 

drought areas, resulting in an upward 

shift in range for many species (IPCC 

2007, pp. 2–5); the higher elevation 

montane habitat could be essential to 

future conservation of the Gunnison’s 

prairie dog. We have no knowledge of 

more detailed climate change 

information specifically for this 

montane portion of the Gunnison’s 

prairie dog range. 

Summary of Factor E 

Although poisoning contributed 

historically to large declines in 

occupied area of Gunnison’s prairie 

dogs, there is no information available 

to indicate that poisoning occurs at 

more than a localized scale today. 

Poisoning could have a negative effect 

on small, isolated populations, 

particularly in conjunction with disease 

and shooting; therefore, poisoning in the 

montane area may be more likely to 

contribute to the decline of the species 

by further fragmenting the small 

populations and curtailing 

recolonization. No information 

currently indicates that drought 

negatively affects or is likely to affect 

the Gunnison’s prairie dog throughout 

its range, or that climate change will 

affect the species within the foreseeable 

future. While poisoning of Gunnison’s 

prairie dogs and the effects of climate 

change in the montane portion of the 

range are issues important to monitor, 

we conclude that no other natural or 

manmade factors are a significant threat 

to this species, at this time, throughout 

all or a significant portion of its range. 

Foreseeable Future 

When determining whether a species 

is in danger of extinction throughout all 

or a significant portion of its range, or 

is likely to become in danger of 

extinction in the foreseeable future, we 

must define that foreseeable future for 

the species. We do this on a case-bycase basis, taking into account a variety 

of species-specific factors such as 

lifespan, genetics, breeding behavior, 

demography, threat-projection 

timeframes, and environmental 

variability. For the purposes of this 

finding, we define foreseeable future 

based on a threat-projection timeframe, 

because plague is likely to be the single 

greatest factor contributing to the 

species’ future conservation status, as 

explained below. 

Life history characteristics are of 

secondary relevance to Gunnison’s 

prairie dog foreseeable future. 

Gunnison’s prairie dogs breed once per 

year and produce an average litter size 

of 3.77. They can become sexually 

mature at 1 year of age, but survivorship 

is less than 60 percent during their first 

year (Seglund et al. 2005, p. 15). These 

characteristics are relevant to the 

species’ ability to sustain stable 

populations in the presence of ongoing, 

low intensity threats such as predation, 

poisoning, and shooting. However, we 

find that the ability of populations to 

recover from plague epizootics is more 

relevant to the foreseeable future of the 

species. 

As described under Factor C above, 

prairie dog populations can experience 

mortality rates of greater than 99 percent 

during plague epizootics and can be 

eradicated within one season due to 

plague. Recovery rates, which are key to 

population survival, depend on several 

factors, including susceptibility to 

plague, frequency of plague outbreaks, 

habitat quality, and distance to other 

colonies available for recolonization. 

Current data frame our analysis and 

help us understand what factors can 

reasonably be anticipated to 

meaningfully affect the species’ future 

conservation status. We have 

documented that Gunnison’s prairie dog 

occupancy varies significantly across its 

range, that susceptibility to extirpation 

by plague is greater in the montane 

portion of the species’ range, and that 

metapopulation structure does not exist 

and recolonization is nearly nonexistent 

in the montane portion of the range. 

While we have data indicating that 

Gunnison’s prairie dog numbers and 

populations have decreased, we 

currently have no data on which to base 

rates of decline in any portion of that 

range, which hinders our ability to 

determine the foreseeable future for the 

species. We must estimate the 

foreseeable future of the Gunnison’s 

prairie dog based on current occupancy 

and our knowledge of the magnitude of 

the threat of plague. Plague has been 

shown to nearly extirpate entire 

population areas over a span of 3 to 10 

years (such as South Park and San Luis 

Valley in Colorado and Moreno Valley 

in New Mexico) (Fitzgerald 1993; 

CDOW 2007; Cully et al. 1997) and can 

extirpate small populations in 1 to 2 

years (Fitzgerald 1970; Lechleitner et al. 

1962; Turner 2001). 

Plague has been present within the 

range of the Gunnison’s prairie dog for 

70 years (Eskey and Haas 1940, p. 6) and 

will likely continue to exist within the 

range in perpetuity, because it remains 

widespread and strongly entrenched 

among wild rodent populations in the 

western United States (Barnes 1993, p. 

31). Current information suggests that 

Gunnison’s prairie dog has not 

developed sufficient immunity to 

reduce the effects of plague; we 

anticipate it will not develop such 

immunity within the foreseeable future. 

Few records document Gunnison’s 


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prairie dog individuals with plague 

antibody titers (Cully et al. 1997, p. 717; 

Cully and Williams 2001, p. 898). 

Individual prairie dogs in the Aubrey 

Valley of Arizona had antigens that 

provided an immune response similar to 

that expected if they had been 

vaccinated; however, the mechanism is 

unknown—that is, we do not know 

whether the response is a result of 

exposure to plague or is innate (Wagner 

and Van Andel 2007, p. 2), and we do 

not know if the number of individual 

prairie dogs that have antigens are 

enough to protect whole colonies. We 

have no documented records of 

resistance being passed to offspring. 

More studies and testing need to be 

conducted on a plague vaccine that has 

had limited success in laboratory 

experiments on black-tailed prairie 

dogs; individual black-tailed prairie 

dogs have developed antigens to plague 

in response to the vaccine. The vaccine 

has not yet been tested on Gunnison’s 

prairie dogs, and even if we had an 

effective vaccine, we currently have no 

method of applying it to prairie dog 

populations. 

We do not have sufficient 

information, such as trend data, on the 

trajectory of plague to develop a precise 

definition of foreseeable future. In the 

70 years plague has been present in 

Gunnison’s prairie dog habitat: (1) 

Populations in the montane portion of 

the range have become isolated and no 

longer comprise a metapopulation 

structure; and (2) populations in the 

prairie portion of the range have 

maintained a metapopulation structure, 

but occupancy has been reduced by 50 

percent or more. The trajectory of 

plague effects is difficult to assess, 

because, as populations are reduced in 

size or extirpated, the effects of plague 

multiply at a faster rate. Using the best 

available information, we find that, if 

occupied habitat within the prairie 

portion of the range was reduced by at 

least 50 percent in 70 years, the species 

could be facing significant effects within 

a much shorter timeframe than another 

70 years. Our best estimate at this time 

is that within half that time, another 35 

years or fewer, plague may eliminate the 

metapopulation structure remaining 

within the prairie portion of the range. 

Therefore, we find that the foreseeable 

future of the Gunnison’s prairie dog is 

35 years. It is possible that Gunnison’s 

prairie dogs may develop immunity to 

plague, or to rebound in numbers that 

enable it to withstand cyclic outbreaks 

of the disease, making the trajectory of 

plague longer than 35 years. It is also 

possible that plague will continue on a 

more rapid trajectory that extirpates 

populations at a rate we can’t anticipate. 

However, we find that an estimate of 35 

years as the foreseeable future of the 

Gunnison’s prairie dog is reasonable, 

because it focuses this status review on 

the known effects from plague, and our 

best assessment that prairie dogs will 

not soon develop immunity to the 

disease. We know of no other species 

that have developed an immunity to 

plague. 

Based on currently available data on 

the continued presence of plague and its 

effects, we have determined that the 

species, rangewide, is not likely to 

become endangered within the 

foreseeable future, which we have 

determined to be the year 2043. 

However, while some populations in the 

montane portion of the range have so far 

persisted, their long-term viability is 

compromised by the lack of 

metapopulation structure. In the prairie 

portion of the range, the many more 

populations and the metapopulation 

structure that enable recolonization after 

plague epizootics, continue to persist, 

and in our judgment, will continue to 

persist into the foreseeable future. 

Significant Portion of the Range 

Analysis 

As required by the Act, we considered 

the five potential threat factors to assess 

whether the Gunnison’s prairie dog is 

threatened or endangered throughout all 

or a significant portion of its range. 

When considering the listing status of 

the species, the first step in the analysis 

is to determine whether the species is in 

danger of extinction throughout all of its 

range. If this is the case, then we list the 

species in its entirety. For instance, if 

the threats to a species are directly 

acting on only a portion of its range, but 

they are at such a large scale that they 

place the entire species in danger of 

extinction, we would list the entire 

species. 

We next consider whether any 

significant portion of the Gunnison’s 

prairie dog range meets the definition of 

endangered or is likely to become 

endangered in the foreseeable future 

(threatened). On March 16, 2007, a 

formal opinion was issued by the 

Solicitor of the Department of the 

Interior, ‘‘The Meaning of ‘In Danger of 

Extinction Throughout All or a 

Significant Portion of Its Range’ ’’ (DOI 

2007). A portion of a species’ range is 

significant if it is part of the current 

range of the species and is important to 

the conservation of the species because 

it contributes meaningfully to the 

representation, resiliency, or 

redundancy of the species. The 

contribution must be at a level such that 

its loss would result in a decrease in the 

ability of the species to persist. 

The first step in determining whether 

a species is threatened or endangered in 

a significant portion of its range is to 

identify any portions of the range of the 

species that warrant further 

consideration. The range of a species 

can theoretically be divided into 

portions in an infinite number of ways. 

To identify portions that warrant further 

consideration, we determine whether 

there is substantial information 

indicating that (1) the portions may be 

significant, and (2) the species may be 

in danger of extinction there or likely to 

become so within the foreseeable future. 

In practice, a key part of this analysis is 

whether the threats are geographically 

concentrated in some way. If the threats 

to the species are essentially uniform 

throughout its range, no portion is likely 

to warrant further consideration. 

Moreover, if any concentration of 

threats applies only to portions of the 

range that are unimportant to the 

conservation of the species, such 

portions will not warrant further 

consideration. 

If we identify any portions that 

warrant further consideration, we then 

determine whether the species is 

threatened or endangered in any 

significant portion. If we determine that 

a portion of the range is not significant, 

we do not determine whether the 

species is threatened or endangered 

there. 

The terms ‘‘resiliency,’’

‘‘redundancy,’’ and ‘‘representation’’ are 

intended to be indicators of the 

conservation value of portions of the 

range. Resiliency of a species allows it 

to recover from periodic disturbances. A 

species will likely be more resilient if 

large populations exist in high-quality 

habitat that is distributed throughout its 

range in a way that captures the 

environmental variability available. A 

portion of the range of a species may 

make a meaningful contribution to the 

resiliency of the species if the area is 

relatively large and contains particularly 

high-quality habitat, or if its location or 

characteristics make it less susceptible 

to certain threats than other portions of 

the range. When evaluating whether or 

how a portion of the range contributes 

to resiliency of the species, we evaluate 

the historical value of the portion and 

how frequently the portion is used by 

the species, if possible. The range 

portion may contribute to resiliency for 

other reasons; for instance, it may 

contain an important concentration of 

certain types of habitat that are 

necessary for the species to carry out its 

life-history functions, such as breeding, 


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feeding, migration, dispersal, or 

wintering. 

Redundancy of populations may be 

needed to provide a margin of safety for 

the species to withstand catastrophic 

events. This concept does not mean that 

any portion that provides redundancy is 

per se a significant portion of the range 

of a species. The idea is to conserve 

enough areas of the range so that 

random perturbations in the system 

only act on a few populations. 

Therefore, we examine each area based 

on whether that area provides an 

increment of redundancy that is 

important to the conservation of the 

species. 

Adequate representation ensures that 

the species’ adaptive capabilities are 

conserved. Specifically, we evaluate a 

range portion to see how it contributes 

to the genetic diversity of the species. 

The loss of genetically based diversity 

may substantially reduce the ability of 

the species to respond and adapt to 

future environmental changes. A 

peripheral population may contribute 

meaningfully to representation if there 

is evidence that it provides genetic 

diversity due to its location on the 

margin of the species’ habitat 

requirements. 

Based on the discussion above, we 

identified the montane portion of the 

current range of the Gunnison’s prairie 

dog as warranting further consideration 

to determine if it is a significant portion 

of the range that is threatened or 

endangered. This portion of the range in 

central and south-central Colorado, and 

north-central New Mexico, constitutes 

approximately 40 percent of the current 

overall range. 

Defining Portions of the Range 

In defining the portion of the current 

range that we considered further, we 

relied on range maps produced by 

mammalogists and geneticists that 

delineate the boundaries of the montane 

and prairie portions of the Gunnison’s 

prairie dog’s range. We believe the 

threats to the species are significantly 

different in the two range portions. The 

geography of each area differs 

significantly, affecting the ability of the 

prairie dog to respond to threats. 

Unpublished genetic analysis shows 

differences in Gunnison’s prairie dogs 

between the two areas (Hafner et al. 

2005, p. 2). This analysis is not yet 

complete enough to definitively indicate 

that two separate subspecies exist; 

however, along with subspecies 

delineation, the data also point to 

possible differences in Gunnison’s 

prairie dog adaptations due to physical 

geography. 

We assessed whether we should 

consider smaller geographic units, such 

as population areas. Given the best 

scientific and commercial information 

available, we found that individual 

population areas did not meaningfully 

contribute to the representation, 

resiliency, or redundancy of the species. 

The scale at which we define the 

range of a particular species, that is, at 

a relatively coarse or fine scale, depends 

on the life history of the species, the 

data available, and the purpose for 

defining the range. 

As with other determinations under 

the Act, we define the current range on 

the basis of the best available data. The 

purpose of defining range (and hence 

the significant portion of the range) is to 

set the boundaries of the protections of 

the Act. Therefore, defining the 

boundaries too narrowly may lead to the 

failure to protect some Gunnison’s 

prairie dogs. We have determined that it 

is appropriate to use a relatively coarse 

scale to capture all of the areas where 

the best available data suggests the 

Gunnison’s prairie dog is likely to 

occur. 

The map boundaries in Figure 1 above 

show the Gunnison’s prairie dog range. 

Discovery of currently existing 

Gunnison’s prairie dog populations 

outside these boundaries is unlikely. 

The map boundaries show the 

significant montane portion, which is 

inclusive of all areas likely to support 

Gunnison’s prairie dog populations in 

the montane habitat. 

Significance of the Montane Range 

When Gunnison’s prairie dog colonies 

are well distributed across their current 

range, which currently includes an 

estimated 5 percent of the historical 

range, they are less susceptible to 

extinction than when colonies are 

confined to only a portion of their range. 

The montane habitat within Gunnison’s 

prairie dog range contains populations 

significant to the overall viability of the 

species, because they represent: 

• Approximately 40 percent of the 

species’ current habitat; 

• Populations in unique, higher 

elevation habitat, and adaptations 

relevant to this habitat; 

• Genetic material substantially 

unique within the range of the 

Gunnison’s prairie dog (Hafner 2004, p. 

6; Hafner et al. 2005, p. 2). 

The relatively large proportion of the 

entire range represented by the montane 

habitat adds a significant number of 

Gunnison’s prairie dog populations 

widely distributed throughout distinct 

geographic areas. Losses of populations 

in montane habitat would affect the 

representation, resiliency, and 

redundancy of the species by increasing 

risk of extirpation by a natural or 

anthropogenic event, reducing adaptive 

characteristics to geographical or 

climatic conditions, and reducing 

remaining genetic variation. 

The most recent literature on climate 

change includes predictions of 

hydrologic changes, higher 

temperatures, and expansion of drought 

areas, resulting in an upward shift in 

range for many species (IPCC 2007, pp. 

2–5); the higher elevation montane 

habitat could be essential to future 

conservation of the Gunnison’s prairie 

dog. These factors lead us to the 

conclusion that loss of the Gunnison’s 

prairie dog within the montane portion 

of its range would reduce the ability of 

the species to persist. 

Status of Montane Range 

If we identify any range portions as 

significant, we then determine whether 

the species is threatened or endangered 

in this significant portion of its range. 

Summary of Factors Affecting the 

Species Within the Montane Portion of 

the Range 

We evaluated whether threats to the 

Gunnison’s prairie dog may affect its 

survival within the montane portion of 

its range, separately from the entire 

range. Our evaluation of threats within 

the montane portion of the range (based 

on information provided in the petition, 

available in our files, and available in 

published and unpublished studies and 

reports) is presented below. 

A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Conservation principles indicate that 

smaller, more isolated populations are 

more vulnerable to extirpation (Barnes 

1993, p. 34; Cully 1993, p. 43; Fitzgerald 

1970, p. 78; Gilpin and Soule 1986, pp. 

30–31; Miller et al. 1994, p. 151; 

Mulhern and Knowles 1995, p. 21; 

Wilcox and Murphy 1985, p. 883; 

Wuerthner 1997, p. 464). Lomolino et 

al. (2003, p. 116) found that persistence 

of Gunnison’s prairie dog colonies 

increased significantly with larger 

colony size and decreased isolation. The 

populations within the montane portion 

of the range are smaller and more 

isolated. However, we found no studies 

or data that specifically assess the 

magnitude of the threats related to 

agriculture land conversions, 

urbanization, grazing, roads, and oil and 

gas leasing, and resulting fragmentation 

within the montane portion of 

Gunnison’s prairie dog habitat. 

After assessing the best available 

science on the magnitude and extent of 


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the effects of agricultural land 

conversion, urbanization, grazing, roads, 

oil and gas development, and 

fragmentation of habitat, we find that 

the destruction, modification, and 

curtailment of Gunnison’s prairie dog’s 

habitat or range are not significant 

threats within the montane portion of 

the range. Agriculture, urbanization, 

roads, and oil and gas development each 

currently affect a small percentage of 

Gunnison’s prairie dog habitat. Effects 

of livestock grazing, while widespread, 

have not resulted in measurable 

population declines. 

B. Overutilization for Commercial, 

Recreational, Scientific, or Educational 

Purposes 

We have determined that shooting 

continues to be a threat to the 

Gunnison’s prairie dog within the 

montane portion of its range and 

contributes to the decline of the species 

when combined with the effects of 

disease (see Factor C below). However, 

this threat is being monitored and 

managed by the States of Colorado and 

New Mexico, and modeling results 

suggest seasonal shooting closures 

implemented in Colorado will likely 

reduce population-level losses. 

Therefore, we have determined that 

overutilization for commercial, 

recreational, scientific, or educational 

purposes is not a significant threat to 

the Gunnison’s prairie dog within the 

montane portion of its range. 

C. Disease or Predation 

Several well-studied colonies within 

the montane portion of the Gunnison’s 

prairie dog range have been documented 

as being extirpated, or nearly so, due to 

plague. The South Park, Colorado, 

population area included estimated 

occupied habitat of 915,000 ac (371,000 

ha) in 1945; 74,000 ac (30,000 ha) in 

1948; and 42 ac (17 ha) in 2002 (CDOW 

2007). This decline was largely due to 

plague and affected a substantial portion 

of the species’ extant occupied habitat 

in Colorado (at least 15 percent). Plague 

resulted in the complete loss, over a 2- 

year period, of a colony within the 

South Park population area (Fitzgerald 

1970, pp. 68–69). A plague event in 

Saguache County, Colorado, that 

progressed across seven colonies in 2 

years left only scattered individuals 

surviving in two colonies (Lechleitner et 

al. 1968, p. 734). In Gunnison, 

Saguache, and Montrose Counties, 

Colorado, plague also was responsible 

for a decline from 15,569 ac (6,228 ha) 

of occupied habitat in 1980, to 770 ac 

(308 ha) in 2002 (note that Montrose 

County is in the Southwest population 

area in prairie habitat) (Capodice and 

Harrell 2003, pp. 5–7). A complete dieoff of a colony due to plague in Chubbs 

Park, Chaffee County, Colorado, 

occurred in 1959 (Lechleitner et al. 

1962, p. 185). In August 1958, the 

population was stable and healthy, but 

in 1959 an epizootic spread 2 mi (3 km) 

within 3 months; prairie dogs continued 

to be absent from the area in 1960 and 

1961, and we have no recent 

information on the existence of prairie 

dogs in that location. 

Approximately 1,000 to 1,500 

Gunnison’s prairie dogs were killed by 

an outbreak of plague in a 148–ac (60–

ha) colony in Curecanti National 

Recreation Area near Gunnison, 

Colorado, in 1981 (Rayor 1985, p. 194). 

A few animals survived the disease and 

Gunnison’s prairie dogs were again 

abundant in the area in 1986 (Cully 

1989, p. 49). In 2002, 252 ac (102 ha) of 

habitat in the Recreation Area were 

occupied by Gunnison’s prairie dog 

colonies (Capodice and Harrell 2003, p. 

23), but the current estimate is 12 ac (4.8 

ha) (Childers 2007, p. 2). Colonies 

within the Recreation Area experienced 

six plague epidemics between 1971 and 

2007. Of the 9 historic Gunnison’s 

prairie dog colonies, 3 are currently 

active, and 2 act as source populations 

for the main prairie dog concentration 

area (Childers 2007, p. 1). If the source 

colonies die off due to plague, 

repopulation may not be possible 

because any other Gunnison’s prairie 

dog populations remaining will be 

separated by distance (more than 6 mi 

(10 km)) and impassable geographical 

features such as rivers and mountains 

(Lomolino et al. 2003, p. 116). 

Recently, plague has been implicated 

in the loss of several large colonies on 

BLM land within the Gunnison, 

Colorado, population area (CDOW 2007, 

p. 4). A large colony southeast of 

Gunnison that was very active in 2005 

was totally devoid of prairie dogs in 

2006 and 2007. Four other large 

colonies in the same vicinity were 

active in 2006, but by 2007, no prairie 

dog activity was observed. Plague is the 

suspected cause of these extirpations 

because of the complete elimination of 

the prairie dogs with no sign of 

poisoning (CDOW 2007, p. 4). 

Fitzgerald (1993, p. 52) expressed 

concern about the status of the 

Gunnison’s prairie dog in Colorado, 

indicating that plague had eliminated 

many populations, including almost all 

of the populations in South Park. He 

also suggested that populations 

appeared to be in poor condition in the 

San Luis Valley and were extirpated 

from the extreme upper Arkansas River 

Valley, as well as Jefferson, Douglas, 

and Lake Counties. These areas 

comprise most of the Gunnison’s prairie 

dog montane habitat in Colorado. 

From 1984 through 1987, a plague 

event reduced the population of 

Gunnison’s prairie dogs in the Moreno 

Valley of New Mexico from more than 

100,000 individuals to between 250 and 

500, a decline of greater than 99 percent 

(Cully et al. 1997, pp. 708–711). 

Although the remaining population 

rebounded (increased in size to a certain 

extent) following the epizootic, another 

plague event swept through the area in 

1988, and the population in July 1996 

was still only a small fraction of what 

it had been in 1984 (Cully et al. 1997, 

p. 717). 

Occupancy modeling performed for 

Colorado in 2005 indicated a lower 

proportion of occupancy in the montane 

portion of the species’ range within 

Colorado (3.2 percent) than in the 

prairie portion within Colorado (16.0 

percent) (Andelt et al. 2006, p. 17; 

CDOW 2007, p. 19). When the study 

was repeated over the same plots in 

2007, occupancy was again found to be 

lower (3.6 percent) in the montane range 

portion in Colorado than in the 

southwestern portion (18.3 percent) 

(CDOW 2007, p. 19). The only recent 

threat responsible for whole population 

declines and extirpations, as 

documented in the studies cited in this 

section, is plague. 

The frequency of plague epizootics 

appears to be high in montane habitat 

due to moister environmental 

conditions that are conducive to greater 

flea densities. The impact of plague 

epizootics in montane habitat is great 

because the small, isolated populations 

cannot recolonize. Within the South 

Park, Gunnison, and Southeast montane 

population areas in Colorado, no prairie 

dog complexes of appreciable size exist, 

and only a few small complexes exist 

within the San Luis Valley population 

area (CDOW 2007, pp. 1–17). Without a 

metapopulation structure, an overall 

decline in persistence takes place 

(Lomolino and Smith 2001, p. 942). 

The landscape status in the montane 

portion of Gunnison’s prairie dog range 

is characterized by fewer, smaller 

colonies that are isolated, and few to no 

complexes or metapopulation structure. 

These factors make the prairie dogs in 

this habitat highly susceptible to plaguerelated declines, and we have no 

evidence of recovery from plague in the 

montane habitat area. 

The studies cited above document the 

serious impact that plague has on 

Gunnison’s prairie dogs within the 

montane portion of the range. Although 

plague antibody titers have been found 

in a few individuals, periodic epizootic 

plague events generally kill more than 


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99 percent of an affected population. 

Whether individual populations recover 

from these epizootics depends on two 

main factors: (1) The availability of 

other source populations to recolonize 

an area; and (2) the frequency of 

epizootic outbreaks, which can reduce 

population numbers more quickly than 

individual prairie dogs from 

neighboring colonies can recolonize. 

Populations in the more mesic 

montane areas of Gunnison’s prairie dog 

range appear to have been widely and 

severely affected by plague. This may be 

partly due to climatic conditions, such 

as higher levels of spring moisture, 

which has been shown to increase flea 

numbers, and in turn, plague outbreaks. 

Isolation of prairie dog populations does 

not seem to protect them from the 

spread of plague, because it appears that 

plague exists with all parts of the range 

at some level and can be spread by 

wider-ranging animals. The case studies 

cited in this section indicate that large 

populations have been repeatedly 

affected by plague and have shown no 

substantial recovery over long periods of 

time—decades in some cases. This has 

left smaller, more scattered populations 

throughout the montane range portion, 

with the result that areas affected by 

plague are less likely to be recolonized 

by nearby populations. While little 

information is currently available on 

prairie dog movement within this 

montane habitat, its geography 

(populations are located in valleys 

between mountainous areas) probably 

impedes the ability of prairie dogs to 

recolonize populations. Within this 

geographic area, CDOW found slightly 

more than 3 percent occupancy of 

surveyed plots (CDOW 2007, p.19). 

Populations within montane habitat 

have three distinct disadvantages in 

resisting the effects of plague: 

(1) A higher frequency of epizootics 

due to the moister montane climate that 

is conducive to higher abundance of 

fleas that spread plague; 

(2) smaller populations that cannot 

recover in numbers from plague 

epizootics; and 

(3) isolated populations and no 

metapopulation structure, due to 

reduced population sizes from past 

plague epizootics and montane 

geography, and therefore a significantly 

limited ability to recolonize. 

After assessing the best available 

science on the magnitude and extent of 

the effects of plague, we find that plague 

is significantly impacting the species in 

the montane portion of its range. 

D. Inadequacy of Existing Regulatory 

Mechanisms 

On the basis on a review of the 

available existing information, it does 

not appear that the inadequacy of 

existing regulatory mechanisms is a 

significant threat to the Gunnison’s 

prairie dog. However, the percentage of 

private lands within the montane 

portion of the species’ range results in 

a paucity of regulatory mechanisms that 

potentially result in increased shooting 

and poisoning, which exacerbate the 

effects of plague in that portion of its 

range. At this time, no regulatory 

mechanisms exist to mitigate the effects 

of plague. 

E. Other Natural or Manmade Factors 

Poisoning could have a negative effect 

on small, isolated populations, 

particularly in conjunction with disease 

and shooting; therefore, poisoning in the 

montane area may be more likely to 

contribute to the decline of the species 

by further fragmenting the small 

populations and curtailing 

recolonization. However, while 

poisoning bears monitoring, at this time, 

we conclude that it is not significantly 

affecting the populations within this 

portion of the range. No information 

currently indicates that drought 

negatively affects, or is likely to affect, 

the Gunnison’s prairie dog within the 

montane portion of its range, or that 

climate change will affect the species 

within the foreseeable future; however, 

various scenarios are plausible. We 

conclude that no other natural or 

manmade factors are a significant threat 

to this species, at this time, throughout 

the montane portion of its range. 

Finding 

The information summarized in this 

status review includes substantial 

information that was not available at the 

time of the 90-day petition finding (71 

FR 6241, February 7, 2006) and other 

information we received during the 

public comment period following the 

publication of the 90-day finding. This 

12-month finding reflects and 

incorporates information we received 

during the public comment period or 

obtained through consultation, literature 

research, and field visits, and responds 

to significant issues identified. We 

determined that the Gunnison’s prairie 

dog does not meet the definition of 

threatened or endangered throughout its 

entire range, because, within 

approximately 60 percent of its range 

(the prairie habitat in the southwestern 

portion of its range), the threats 

(primarily plague) are not of a 

magnitude that currently puts the 

species in danger of extinction 

(endangered), or makes it likely to 

become endangered within the 

foreseeable future (threatened). 

However, we determined that the 

Gunnison’s prairie dog is warranted for 

listing within the montane portion of its 

range (approximately 40 percent of the 

species total range). 

The determination of a finding of 

threatened or endangered involves 

weighing the magnitude and immediacy 

of the threats. The cumulative 

magnitude of threats within the 

montane portion of the range is high. 

Immediacy of threats varies 

geographically across the montane 

range, but is high in areas of the 

montane habitat where populations 

have already been extirpated, primarily 

the South Park and Southeast 

population areas. 

Within the prairie portion of the 

Gunnison’s prairie dog’s range, colonies 

are subject to the same threats, but at a 

different magnitude. Plague has the 

same potential to reduce population size 

significantly there as in montane 

habitat, but due to more open 

geography, an existing metapopulation 

structure, larger population sizes, and 

proximity of other colonies, 

recolonization has been observed. The 

ability of populations to recolonize 

relatively quickly enables them to 

recover more fully between plague 

enzootics. Ability to recolonize in 

prairie habitat also enables Gunnison’s 

prairie dog populations to recover from 

poisoning and shooting, which act to 

exacerbate the more significant threat 

from plague. The species’ status in this 

portion of the range is characterized by 

a metapopulation structure, and larger 

colonies and complexes that are better 

able to recover from plague epidemics, 

to be recolonized after plague 

epizootics, and even to colonize new 

areas. 

We determined that the Gunnison’s 

prairie dog is warranted for listing 

within the montane portion of its range 

(approximately 40 percent of the species 

total range). We find that threats, 

primarily plague, exist in the montane 

portion of their range at a magnitude 

that make the species likely to become 

threatened or endangered within the 

foreseeable future, which we have 

determined to be the year 2043. We 

determined that Gunnison’s prairie dog 

populations within the prairie portion 

of the range continue to be viable due 

to the functioning metapopulation 

structure and the apparent resistance to 

plague epizootics within the Aubrey 

Valley, Arizona, complex. Therefore, we 

find that the Gunnison’s prairie dog 

does not warrant listing throughout its 


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entire range, but that populations within 

the montane portion of its range are 

significant to the continued existence of 

the species and warrants listing in that 

portion only (see discussion under 

Significant Portion of the Range 

Analysis). However, listing the montane 

Gunnison’s prairie dog is warranted but 

precluded at this time by pending 

proposals for other species with higher 

listing priorities based on taxonomic 

uniqueness (the only species described 

for the genus), or other species that are 

not currently listed (see discussion 

under Preclusion and Expeditious 

Progress). 

If future genetic analyses or 

taxonomic studies indicate conclusively 

that two subspecies of Gunnison’s 

prairie dogs exist, this would affect our 

proposed listing. Instead of defining the 

montane habitat as a significant portion 

of the range, we would propose listing 

the subspecies that exists in that habitat. 

Sylvatic plague is the only significant 

factor affecting the future conservation 

status of the species. Within the 

montane portion of the species’ range, 

the threat of plague has greater 

magnitude, and colony recovery from 

plague is slow or nonexistent. 

Distributional data indicate that the 

species’ status in this portion of its 

range is characterized by lower 

occupancy, smaller colony sizes, and 

fragmented and isolated colonies that 

impede recovery and persistence of 

populations. Reliable data regarding the 

status of the Gunnison’s prairie dog are 

predominantly in the form of percent 

occupancy studies, which indicate 

significantly lower occupancy in 

montane habitat (for Colorado, 

approximately 3.6 percent versus 18.3 

percent in prairie habitat). For example, 

the South Park population area, which 

comprises nearly 15 percent of the 

species’ habitat in Colorado, is nearly 

devoid of the species. Within the four 

montane population areas in Colorado, 

prairie dog complexes exist within only 

one, and those complexes are few and 

small. With little or no metapopulation 

structure, an overall decline in 

persistence is apparent in the montane 

habitat. 

Populations within montane habitat 

have three distinct disadvantages in 

resisting the effects of plague: (1) A 

higher frequency of epizootics due to 

the moister montane climate that is 

conducive to higher abundance of fleas 

that spread plague; (2) smaller 

populations that cannot recover in 

numbers from plague epizootics; and (3) 

isolated populations and little or no 

metapopulation structure, due to 

reduced population sizes from past 

plague epizootics and montane 

geography, and therefore a significantly 

limited ability to recolonize. 

Some lands within the montane range 

supporting the Gunnison’s prairie dog 

are controlled by Federal or State 

agencies, or have been set aside as open 

space by local governments. However, a 

greater portion of the montane range is 

private land with fewer regulatory 

mechanisms in place for conserving 

prairie dogs. 

We found that poisoning and shooting 

are not significant threats rangewide. 

While they can have greater impacts on 

small populations by compounding the 

effects from the primary threat of plague 

and further decreasing colony size and 

fragmenting and isolating colonies, at 

this time poisoning and shooting do not 

appear to be occurring at a level that 

raises concern above that related to 

plague. Cumulative threats do, however, 

impede recovery of some populations 

and imperil others. Where recovery does 

not occur, Gunnison’s prairie dog 

populations are likely to remain small, 

fragmented, and susceptible to 

extirpation. 

The following summarizes the key 

points leading to our finding: 

(1) Historic data indicate a decline 

from 24,000,000 ac (9,700,000 ha) of 

occupied habitat to between 340,000 

and 500,000 ac (136,000 to 200,000 ha). 

(2) Recent data indicate that 

approximately 3.6 percent of potential 

Gunnison’s prairie dog habitat is 

occupied in the montane portion of the 

range, as compared to 18.3 percent 

occupancy in the prairie portion of the 

range. 

(3) The Gunnison’s prairie dog 

occupies two genetically important 

areas of its range (prairie and montane 

portions). The two portions have 

different geographical features and 

different responses to plague. 

(4) Plague has resulted in large 

reductions in prairie dogs and occupied 

habitat within both portions of the 

range. The prairie portion of the range 

is responding to plague by recolonizing 

affected populations. Within the 

montane portion of the range, the plague 

response is more significant (large 

population losses, loss of all 

metapopulation structure, nearly no 

recolonization occurring, and entire 

population areas nearly devoid of 

prairie dogs). 

(5) We determined that the 

Gunnison’s prairie dog is warranted for 

listing in the montane portion because: 

(A) The montane portion of the range 

is significant to the species’ viability (it 

represents approximately 40 percent of 

the species’ habitat; populations are 

adapted to unique, montane habitat; and 

these animals are genetically unique). 

(B) Loss of Gunnison’s prairie dogs in 

the montane portion would affect: 

(i) resiliency of the species, because 

the montane portion represents 

approximately 40 percent of the species 

range, and the small, isolated 

populations are not likely to rebound 

after decimation from plague; 

(ii) redundancy of the species, 

because random perturbations are not 

likely to act equally on both the 

montane and prairie portions; and 

(iii) representation of the species, 

because the montane population is 

genetically distinct from the prairie 

population and the species’ remaining 

genetic diversity would be reduced. 

(C) The species is warranted for 

listing in this portion of the range 

because: 

(i) Occupancy data (3 percent) is 

significantly lower in the montane range 

portion. 

(ii) The montane portion of the range 

no longer has a metapopulation 

structure, and populations reduced by 

plague have not rebounded; 

repopulation from nearby populations 

has been curtailed by distance and 

geographical barriers. 

(iii) The two portions of the range are 

separated by mountain ranges that 

almost completely limit prairie dog 

movement between them. 

(iv) Populations within the montane 

portion of the range are separated from 

each other by four mountain ranges and 

several large rivers, which preclude 

repopulation after plague epizootics. 

(v) Some entire population areas 

within montane range are now nearly 

devoid of Gunnison’s prairie dogs. 

(vi) Plague appears to be more 

prevalent in the montane portion of the 

range, possibly due to greater flea 

populations that thrive in moister 

climates. 

We determined that the magnitude of 

threats affecting the Gunnison’s prairie 

dog in the montane portion of its range 

is ‘‘high,’’ because plague is 

significantly affecting the remaining 

small, isolated populations, and plague 

epizootics can extirpate populations 

there within a short timeframe (3 to 10 

years); metapopulation structure in the 

prairie portion of the range exists, 

facilitating recolonization when 

populations are extirpated. We find that 

the threat posed by plague is 

‘‘imminent’’ because plague epizootics 

are known to be occurring and the 

effects are measurable. Therefore, 

pursuant to our September 21, 1983 (48 

FR 43098) Listing and Recovery Priority 

Guidelines, we assign a LPN of 2 to this 

portion of the species’ range. 

We reviewed the available 

information to determine if existing and 


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foreseeable threats to the Gunnison’s 

prairie dog within montane habitat are 

of sufficient extent and magnitude to 

require emergency listing as threatened 

or endangered. We have determined that 

an emergency listing is not warranted 

for this species at this time, because 

populations are currently not threatened 

in the prairie portion of the range, and 

because emergency listing would not 

lessen the effects from plague, which is 

the significant threat in the montane 

portion of the range. 

Preclusion and Expeditious Progress 

Preclusion is a function of the listing 

priority of a species in relation to the 

resources that are available and 

competing demands for those resources. 

Thus, in any given fiscal year (FY), 

multiple factors dictate whether it will 

be possible to undertake work on a 

proposed listing regulation or whether 

promulgation of such a proposal is 

warranted but precluded by higherpriority listing actions. 

The resources available for listing 

actions are determined through the 

annual Congressional appropriations 

process. The appropriation for the 

Listing Program is available to support 

work involving the following listing 

actions: proposed and final listing rules; 

90-day and 12-month findings on 

petitions to add species to the Lists of 

Endangered and Threatened Wildlife 

and Plants or to change the status of a 

species from threatened to endangered; 

annual determinations on prior 

‘‘warranted but precluded’’ petition 

findings as required under section 

4(b)(3)(C)(i) of the Act; proposed and 

final rules designating critical habitat; 

and litigation-related, administrative, 

and program management functions 

(including preparing and allocating 

budgets, responding to Congressional 

and public inquiries, and conducting 

public outreach regarding listing and 

critical habitat). The work involved in 

preparing various listing documents can 

be extensive and may include, but is not 

limited to: gathering and assessing the 

best scientific and commercial data 

available and conducting analyses used 

as the basis for our decisions; writing 

and publishing documents; and 

obtaining, reviewing, and evaluating 

public comments and peer review 

comments on proposed rules and 

incorporating relevant information into 

final rules. The number of listing 

actions that we can undertake in a given 

year also is influenced by the 

complexity of those listing actions; that 

is, more complex actions generally are 

more costly. For example, during the 

past several years, the cost (excluding 

publication costs) for preparing a 12- 

month finding, without a proposed rule, 

has ranged from approximately $11,000 

for one species with a restricted range 

and involving a relatively 

uncomplicated analysis to $305,000 for 

another species that is wide-ranging and 

involving a complex analysis. 

We cannot spend more than is 

appropriated for the Listing Program 

without violating the Anti-Deficiency 

Act (see 31 U.S.C. 1341(a)(1)(A)). In 

addition, in FY 1998 and for each fiscal 

year since then, Congress has placed a 

statutory cap on funds which may be 

expended for the Listing Program, equal 

to the amount expressly appropriated 

for that purpose in that fiscal year. This 

cap was designed to prevent funds 

appropriated for other functions under 

the Act (for example, recovery funds for 

removing species from the Lists), or for 

other Service programs, from being used 

for Listing Program actions (see House 

Report 105–163, 105th Congress, 1st 

Session, July 1, 1997). 

Recognizing that designation of 

critical habitat for species already listed 

would consume most of the overall 

Listing Program appropriation, Congress 

also put a critical habitat subcap in 

place in FY 2002 and has retained it 

each subsequent year to ensure that 

some funds are available for other work 

in the Listing Program: ‘‘The critical 

habitat designation subcap will ensure 

that some funding is available to 

address other listing activities’’ (House 

Report No. 107–103, 107th Congress, 1st 

Session, June 19, 2001). In FY 2002 and 

each year until FY 2006, the Service has 

had to use virtually the entire critical 

habitat subcap to address courtmandated designations of critical 

habitat, and consequently none of the 

critical habitat subcap funds have been 

available for other listing activities. In 

FY 2007, we were able to use some of 

the critical habitat subcap funds to fund 

proposed listing determinations for 

high-priority candidate species; we 

expect to also be able to do this in FY 

2008. 

Thus, through the listing cap, the 

critical habitat subcap, and the amount 

of funds needed to address courtmandated critical habitat designations, 

Congress and the courts have in effect 

determined the amount of money 

available for other listing activities. 

Therefore, the funds in the listing cap, 

other than those needed to address 

court-mandated critical habitat for 

already listed species, set the limits on 

our determinations of preclusion and 

expeditious progress. 

Congress also recognized that the 

availability of resources was the key 

element in deciding whether, when 

making a 12-month petition finding, we 

would prepare and issue a listing 

proposal or make a ‘‘warranted but 

precluded’’ finding for a given species. 

The Conference Report accompanying 

Public Law 97–304, which established 

the current statutory deadlines and the 

warranted-but-precluded finding, states 

(in a discussion on 90-day petition 

findings that by its own terms also 

covers 12-month findings) that the 

deadlines were ‘‘not intended to allow 

the Secretary to delay commencing the 

rulemaking process for any reason other 

than that the existence of pending or 

imminent proposals to list species 

subject to a greater degree of threat 

would make allocation of resources to 

such a petition [that is, for a lowerranking species] unwise.’’

In FY 2008, expeditious progress is 

that amount of work that can be 

achieved with $8,206,940, which is the 

amount of money that Congress 

appropriated for the Listing Program at 

this time (that is, the portion of the 

Listing Program funding not related to 

critical habitat designations for species 

that are already listed). Our process is 

to make our determinations of 

preclusion on a nationwide basis to 

ensure that the species most in need of 

listing will be addressed first and also 

because we allocate our listing budget 

on a nationwide basis. The $8,206,940 

for listing activities (that is, the portion 

of the Listing Program funding not 

related to critical habitat designations 

for species that already are listed) will 

be used to fund work in the following 

categories: compliance with court orders 

and court-approved settlement 

agreements requiring that petition 

findings or listing determinations be 

completed by a specific date; section 4 

(of the Act) listing actions with absolute 

statutory deadlines; essential litigationrelated, administrative, and program 

management functions; and highpriority listing actions. The allocations 

for each specific listing action are 

identified in the Service’s FY 2008 Draft 

Allocation Table (part of our 

administrative record). We are working 

on completing our allocation at this 

time. More funds are available in FY 

2008 than in previous years to work on 

listing actions that are not the subject of 

court orders or court-approved 

settlement agreements. 

Our decision that a proposed rule to 

list the montane portion of the 

Gunnison’s prairie dog is warranted but 

precluded includes consideration of its 

listing priority. In accordance with 

guidance we published on September 

21, 1983, we assign an LPN to each 

candidate species (48 FR 43098). Such 

a priority ranking guidance system is 

required under section 4(h)(3) of the Act 


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(16 U.S.C. 1533(h)(3)). Using this 

guidance, we assign each candidate an 

LPN of 1 to 12, depending on the 

magnitude of threats (high vs. moderate 

to low), immediacy of threats (imminent 

or non-imminent), and taxonomic status 

of the species, in order of priority 

(monotypic genus (a species that is the 

sole member of a genus), species, 

subspecies, distinct population segment, 

or significant portion of the range). The 

lower the listing priority number, the 

higher the listing priority (that is, a 

species with an LPN of 1 would have 

the highest listing priority). 

We currently have more than 120 

species with an LPN of 2. Therefore, we 

further rank the candidate species with 

an LPN of 2 by using the following 

extinction-risk type criteria: 

International Union for the 

Conservation of Nature and Natural 

Resources (IUCN) Red list status/rank, 

Heritage rank (provided by 

NatureServe), Heritage threat rank 

(provided by NatureServe), and species 

currently with fewer than 50 

individuals, or 4 or fewer populations. 

Those species with the highest IUCN 

rank (critically endangered), the highest 

Heritage rank (G1), the highest Heritage 

threat rank (substantial, imminent 

threats), and currently with fewer than 

50 individuals, or fewer than 4 

populations, comprise a list of 

approximately 40 candidate species 

(‘‘Top 40’’). These 40 candidate species 

have the highest priority to receive 

funding to work on a proposed listing 

determination. To be more efficient in 

our listing process, as we work on 

proposed rules for these species in the 

next several years, we are preparing 

multi-species proposals when 

appropriate, and these may include 

species with lower priority if they 

overlap geographically or have the same 

threats as a species with an LPN of 2. 

In addition, available staff resources are 

also a factor in determining highpriority species provided with funding. 

Finally, proposed rules for 

reclassification of threatened species to 

endangered are lower priority, since the 

listing of the species already affords the 

protection of the Act and implementing 

regulations. We assigned the montane 

portion of the Gunnison’s prairie dog an 

LPN of 5, based on our finding that the 

species faces threats of high magnitude 

that are not imminent. 

As explained above, a determination 

that listing is warranted but precluded 

must also demonstrate that expeditious 

progress is being made to add or remove 

qualified species to and from the Lists 

of Endangered and Threatened Wildlife 

and Plants. (We note that we do not 

discuss specific actions taken on 

progress towards removing species from 

the Lists because that work is conducted 

using appropriations for our Recovery 

program, a separately budgeted 

component of the Endangered Species 

Program. As explained above in our 

description of the statutory cap on 

Listing Program funds, the Recovery 

Program funds and actions supported by 

them cannot be considered in 

determining expeditious progress made 

in the Listing Program.) As with our 

‘‘precluded’’ finding, expeditious 

progress in adding qualified species to 

the Lists is a function of the resources 

available and the competing demands 

for those funds. Our expeditious 

progress in FY 2007 in the Listing 

Program, up to the date of making this 

finding for the Gunnison’s prairie dog, 

included preparing and publishing the 

following determinations: 

FY 2007 COMPLETED LISTING ACTIONS

Publication date Title Actions FR pages 

10/11/2006 ......... Withdrawal of the Proposed Rule To List the Cow Head Tui 

Chub (Gila biocolor vaccaceps) as Endangered.

Final withdrawal, Threats eliminated.71 FR 59700–59711 

10/11/2006 ......... Revised 12-Month Finding for the Beaver Cave Beetle 

(Pseudanophthalmus major).

Notice of 12-month petition 

finding, Not warranted.

71 FR 59711–59714 

11/14/2006 ......... 12-Month Finding on a Petition To List the Island Marble Butterfly (Euchloe ausonides insulanus) as Threatened or Endangered.Notice of 12-month petition 

finding, Not warranted.

71 FR 66292–66298 

11/14/2006 ......... 90-Day Finding for a Petition To List the Kennebec River Population of Anadromous Atlantic Salmon as Part of the Endangered Gulf of Maine Distinct Population Segment.Notice of 90-day petition finding, Substantial.71 FR 66298–66301 

11/21/2006 ......... 90-Day Finding on a Petition To List the Columbian SharpTailed Grouse as Threatened or Endangered.Notice of 90-day petition finding, Not substantial.71 FR 67318–67325 

12/5/2006 ........... 90-Day Finding on a Petition To List the Tricolored Blackbird as 

Threatened or Endangered.

Notice of 90-day petition finding, Not substantial.71 FR 70483–70492 

12/6/2006 ........... 12-Month Finding on a Petition To List the Cerulean Warbler 

(Dendroica cerulea) as Threatened with Critical Habitat.

Notice of 12-month petition 

finding, Not warranted.

71 FR 70717–70733 

12/6/2006 ........... 90-Day Finding on a Petition To List the Upper Tidal Potomac 

River Population of the Northern Water Snake (Nerodia 

sipedon) as an Endangered Distinct Population Segment.

Notice of 90-day petition finding, Not substantial.71 FR 70715–70717 

12/14/2006 ......... 90-Day Finding on a Petition To Remove the Uinta Basin 

Hookless Cactus From the List of Endangered and Threatened Plants; 90-Day Finding on a Petition To List the 

Pariette Cactus as Threatened or Endangered.

Notice of 5-year review, Initiation.

Notice of 90-day petition finding, Not substantial.

Notice of 90-day petition finding, Substantial.

71 FR 75215–75220 

12/19/2006 ......... Withdrawal of Proposed Rule To List Penstemon grahamii 

(Graham’s beardtongue) as Threatened With Critical Habitat.

Notice of withdrawal, More 

abundant than believed, or 

diminished threats.

71 FR 76023–76035 

12/19/2006 ......... 90-Day Finding on Petitions To List the Mono Basin Area Population of the Greater Sage-Grouse as Threatened or Endangered.Notice of 90-day petition finding, Not substantial.71 FR 76057–76079 

1/9/2007 ............. 12-Month petition finding and Proposed Rule To List the Polar 

Bear (Ursus maritimus) as Threatened Throughout Its 

Range; Proposed Rule.

Notice of 12-month petition 

finding, Warranted.

Proposed Listing, Threatened ..

72 FR 1063–1099 


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FY 2007 COMPLETED LISTING ACTIONS—Continued 

Publication date Title Actions FR pages 

1/10/2007 ........... Endangered and Threatened Wildlife and Plants; Clarification of 

Significant Portion of the Range for the Contiguous United 

States Distinct Population Segment of the Canada Lynx.

Clarification of findings ............. 72 FR 1186–1189 

1/12/2007 ........... Withdrawal of Proposed Rule To List Lepidium papilliferum 

(Slickspot Peppergrass).

Notice of withdrawal, More 

abundant than believed, or 

diminished threats.

72 FR 1621–1644 

2/2/2007 ............. 12-Month Finding on a Petition To List the American Eel as 

Threatened or Endangered.

Notice of 12-month petition 

finding, Not warranted.

72 FR 4967–4997 

2/13/2007 ........... 90-Day Finding on a Petition To List the Jollyville Plateau Salamander as Endangered.Notice of 90-day petition finding, Substantial.72 FR 6699–6703 

2/13/2007 ........... 90-Day Finding on a Petition To List the San Felipe Gambusia 

as Threatened or Endangered.

Notice of 90-day petition finding, Not substantial.72 FR 6703–6707 

2/14/2007 ........... 90-Day Finding on a Petition To List Astragalus debequaeus 

(DeBeque milkvetch) as Threatened or Endangered.

Notice of 90-day petition finding, Not substantial.72 FR 6998–7005 

2/21/2007 ........... 90-Day Finding on a Petition To Reclassify the Utah Prairie 

Dog From Threatened to Endangered and Initiation of a 5- 

Year Review.

Notice of 5-year review, Initiation.

Notice of 90-day petition finding, Not substantial.

72 FR 7843–7852 

3/8/2007 ............. 90-Day Finding on a Petition To List the Monongahela River 

Basin Population of the Longnose Sucker as Endangered.

Notice of 90-day petition finding, Not substantial.72 FR 10477–10480 

03/29/2007 ......... 90-Day Finding on a Petition To List the Siskiyou Mountains 

Salamander and Scott Bar Salamander as Threatened or Endangered.

Notice of 90-day petition finding, Substantial.72 FR 14750–14759 

04/24/2007 ......... Revised 12-Month Finding for Upper Missouri River Distinct 

Population Segment of Fluvial Arctic Grayling.

Notice of 12-month petition 

finding, Not warranted.

72 FR 20305–20314 

05/02/2007 ......... 12-Month Finding on a Petition To List the Sand Mountain Blue 

Butterfly (Euphilotes pallescens ssp. arenamontana) as 

Threatened or Endangered with Critical Habitat.

Notice of 12-month petition 

finding, Not warranted.

72 FR 24253–24263 

05/22/2007 ......... Status of the Rio Grande Cutthroat Trout ................................... Notice of Review ...................... 72 FR 28864–28665 

05/30/2007 ......... 90-Day Finding on a Petition To List the Mt. Charleston Blue 

Butterfly as Threatened or Endangered.

Notice of 90-day petition finding, Substantial.72 FR 29933–29941 

06/05/2007 ......... 12-Month Finding on a Petition To List the Wolverine as 

Threatened or Endangered.

Notice of Review ...................... 72 FR 31048–31049 

06/06/2007 ......... 90-Day Finding on a Petition To List the Yellow-Billed Loon as 

Threatened or Endangered.

Notice of 90-day petition finding, Substantial.72 FR 31256–31264 

06/13/2007 ......... 12-Month Finding for a Petition To List the Colorado River Cutthroat Trout as Threatened or Endangered.Notice of 12-month petition 

finding, Not warranted.

72 FR 32589–32605 

06/25/2007 ......... 12-Month Finding on a Petition To List the Sierra Nevada Distinct Population Segment of the Mountain Yellow-Legged 

Frog (Rana muscosa).

Notice of amended 12-month 

petition finding, Warranted 

but precluded.

72 FR 34657–34661 

07/05/2007 ......... 12-Month Finding on a Petition To List the Casey’s June Beetle 

(Dinacoma caseyi) as Endangered With Critical Habitat.

Notice of 12-month petition 

finding, Warranted but precluded.

72 FR 36635–36646 

08/15/2007 ......... 90-Day Finding on a Petition To List the Yellowstone National 

Park Bison Herd as Endangered.

Notice of 90-day petition finding, Not substantial.72 FR 45717–45722 

08/16/2007 ......... 90-Day Finding on a Petition To List Astragalus anserinus 

(Goose Creek milk-vetch) as Threatened or Endangered.

Notice of 90-day petition finding, Substantial.72 FR 46023–46030 

8/28/2007 ........... 12-Month Finding on a Petition To List the Gunnison’s Prairie 

Dog as Threatened or Endangered.

Notice of Review ...................... 72 FR 49245–49246 

9/11/2007 ........... 90-Day Finding on a Petition To List Kenk’s Amphipod, Virginia 

Well Amphipod, and the Copepod Acanthocyclops 

columbiensis as Endangered.

Notice of 90-day petition finding, Not substantial.72 FR 51766–51770 

9/18/2007 ........... 12-month Finding on a Petition To List Sclerocactus 

brevispinus (Pariette cactus) as an Endangered or Threatened Species; Taxonomic Change From Sclerocactus 

glaucus to Sclerocactus brevispinus, S. glaucus, and S. 

wetlandicus.

Notice of 12-month petition 

finding for uplisting, Warranted but precluded.

72 FR 53211–53222 

In FY 2007, we provided funds to 

work on proposed listing 

determinations for the following highpriority species: 3 southeastern aquatic 

species (Georgia pigtoe, interrupted 

rocksnail, and rough hornsnail), 2 Oahu 

plants (Doryopteris takeuchii, Melicope 

hiiakae), 31 Kauai species (Kauai 

creeper, Drosophila attigua, Astelia 

waialealae, Canavalia napaliensis, 

Chamaesyce eleanoriae, Chamaesyce 

remyi var. kauaiensis, Chamaesyce 

remyi var. remyi, Charpentiera 

densiflora, Cyanea eleeleensis, Cyanea 

kuhihewa, Cyrtandra oenobarba, 

Dubautia imbricata ssp. imbricata, 

Dubautia plantaginea ssp. magnifolia, 

Dubautia waialealae, Geranium 

kauaiense, Keysseria erici, Keysseria 

helenae, Labordia helleri, Labordia 

pumila, Lysimachia daphnoides, 

Melicope degeneri, Melicope paniculata, 

Melicope puberula, Myrsine mezii, 

Pittosporum napaliense, Platydesma 

rostrata, Pritchardia hardyi, Psychotria 

grandiflora, Psychotria hobdyi, 

Schiedea attenuata, Stenogyne kealiae), 

4 Hawaiian damselflies (Megalagrion 

nesiotes, Megalagrion leptodemas, 

Megalagrion oceanicum, Megalagrion 


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pacificum), and one Hawaiian plant 

(Phyllostegia hispida (no common 

name)). In FY 2008, we are continuing 

to work on these listing proposals (we 

are now including an additional 17 

species in the Kauai species proposed 

listing determination package). In 

addition, we are continuing to work on 

several other determinations listed 

below, which we funded in FY 2007 

and are scheduled to complete in FY 

2008. 

ACTIONS FUNDED IN FY 2007 THAT HAVE YET TO BE COMPLETED

Species Action 

Actions Subject to Court Order/Settlement Agreement 

Wolverine ........................................................................................................................................ 12-month petition finding (remand). 

Western sage grouse ...................................................................................................................... 90-day petition finding (remand). 

Rio Grande cutthroat trout .............................................................................................................. Candidate assessment (remand). 

Actions with Statutory Deadlines 

Polar bear ........................................................................................................................................ Final listing determination. 

Ozark chinquapin ............................................................................................................................ 90-day petition finding. 

Tucson shovel-nosed snake ........................................................................................................... 90-day petition finding. 

Gopher tortoise—Florida population ............................................................................................... 90-day petition finding. 

Sacramento valley tiger beetle ....................................................................................................... 90-day petition finding. 

Eagle lake trout ............................................................................................................................... 90-day petition finding. 

Smooth billed ani ............................................................................................................................ 90-day petition finding. 

Mojave ground squirrel ................................................................................................................... 90-day petition finding. 

Gopher Tortoise—eastern population ............................................................................................. 90-day petition finding. 

Bay Springs salamander ................................................................................................................. 90-day petition finding. 

Tehachapi slender salamander ....................................................................................................... 90-day petition finding. 

Coaster brook trout ......................................................................................................................... 90-day petition finding. 

Mojave fringe-toed lizard ................................................................................................................. 90-day petition finding. 

Evening primrose ............................................................................................................................ 90-day petition finding. 

Palm Springs pocket mouse ........................................................................................................... 90-day petition finding. 

Northern leopard frog ...................................................................................................................... 90-day petition finding. 

Shrike, Island loggerhead ............................................................................................................... 90-day petition finding. 

Cactus ferruginous pygmy owl ........................................................................................................ 90-day petition finding. 

Our expeditious progress so far in FY 

2008 in the Listing Program, includes 

preparing and publishing the following: 

FY 2008 COMPLETED LISTING ACTIONS

Publication date Title Actions FR Pages 

10/09/2007 ......... 90-Day Finding on a Petition to List the Black-Footed Albatross 

(Phoebastria nigripes) as Threatened or Endangered.

Notice of 90-day Petition Finding, Substantial.72 FR 57278–57283 

10/09/2007 ......... 90-Day Finding on a Petition To List the Giant Palouse Earthworm as Threatened or Endangered.Notice of 90-day Petition Finding, Not substantial.72 FR 57273–57276 

10/23/2007 ......... 90-Day Finding on a Petition To List the Mountain Whitefish 

(Prosopium williamsoni) in the Big Lost River, ID, as Threatened or Endangered.

Notice of 90-day Petition Finding, Not substantial.72 FR 59983–59989 

10/23/2007 ......... 90-Day Finding on a Petition To List the Summer-Run Kokanee 

Population in Issaquah Creek, WA, as Threatened or Endangered.

Notice of 90-day Petition Finding, Not substantial.72 FR 59979–59983 

11/08/2007 ......... Response to Court on Significant Portion of the Range, and 

Evaluation of Distinct Population Segments, for the Queen 

Charlotte Goshawk.

Response to Court ................... 72 FR 63123–63140 

12/13/07 ............. 12-Month Finding on a Petition To List the Jollyville Plateau 

salamander (Eurycea tonkawae) as Endangered With Critical 

Habitat.

Notice of 12-month Petition 

Finding, Warranted but Precluded.

72 FR 71039–71054 

1/08/08 ............... 90-Day Finding on a Petition To List the Pygmy Rabbit 

(Brachylagus idahoensis) as Threatened or Endangered.

Notice of 90-day Petition Finding, Substantial.73 FR 1312–1313 

1/24/2008 ........... 12-Month Finding on a Petition To List the Siskiyou Mountains 

Salamander (Plethodon stormi) and Scott Bar Salamander 

(Plethodon asupak) as Threatened or Endangered.

Notice of 12-month Petition 

Finding, Not Warranted.

73 FR 4379–4418 

Our expeditious progress also 

includes work on listing actions, which 

we are funding in FY 2008. These 

actions are listed below. We are 

conducting work on those actions in the 

top section of the table under a deadline 

set by a court. Actions in the middle 

section of the table are being conducted 

to meet statutory timelines, that is, 

timelines required under the Act. 

Actions in the bottom section of the 

table are high priority listing actions, 

which include at least one or more 

species with an LPN of 2, available staff 

resources, and when appropriate, 


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species with a lower priority if they 

overlap geographically or have the same 

threats as the species with the high 

priority. 

ACTIONS ANTICIPATED TO BE FUNDED IN FY 2008 THAT HAVE YET TO BE COMPLETED

Species Action 

Actions Subject to Court Order/Settlement Agreement 

Bonneville cutthroat trout ................................................................................................................ 12-month petition finding (remand). 

Actions With Statutory Deadlines 

Polar bear ........................................................................................................................................ Final listing determination. 

3 Southeastern aquatic species ...................................................................................................... Final listing. 

Phyllostegia hispida ........................................................................................................................ Final listing. 

Yellow-billed loon ............................................................................................................................ 12-month petition finding. 

Black-footed albatross ..................................................................................................................... 12-month petition finding. 

Mount Charleston blue butterfly ...................................................................................................... 12-month petition finding. 

Goose Creek milk-vetch .................................................................................................................. 12-month petition finding. 

White-tailed prairie dog ................................................................................................................... 12-month petition finding. 

Mono Basin sage grouse (vol. remand) ......................................................................................... 90-day petition finding. 

Ashy storm petrel ............................................................................................................................ 90-day petition finding. 

Longfin smelt—San Fran. Bay population ...................................................................................... 90-day petition finding. 

Black-tailed prairie dog ................................................................................................................... 90-day petition finding. 

Lynx (include New Mexico in listing) .............................................................................................. 90-day petition finding. 

Wyoming pocket gopher ................................................................................................................. 90-day petition finding. 

Llanero coqui ................................................................................................................................... 90-day petition finding. 

Least chub ....................................................................................................................................... 90-day petition finding. 

American pika ................................................................................................................................. 90-day petition finding. 

Dusky tree vole ............................................................................................................................... 90-day petition finding. 

Sacramento Mts. checkerspot butterfly .......................................................................................... 90-day petition finding. 

Kokanee—Lake Sammamish population ........................................................................................ 90-day petition finding. 

206 species ..................................................................................................................................... 90-day petition finding. 

475 Southwestern species .............................................................................................................. 90-day petition finding. 

High Priority Listing Actions 

31 Kauai species 1 .......................................................................................................................... Proposed listing. 

8 packages of high-priority candidate species ............................................................................... Proposed listing. 

1Funds used for this listing action were also provided in FY 2007. 

We have endeavored to make our 

listing actions as efficient and timely as 

possible, given the requirements of the 

relevant law and regulations, and 

constraints relating to workload and 

personnel. We are continually 

considering ways to streamline 

processes or achieve economies of scale, 

such as by batching related actions 

together. Given our limited budget for 

implementing section 4 of the Act, these 

actions described above collectively 

constitute expeditious progress. 

Conclusion 

We will add the montane portion of 

the Gunnison’s prairie dog to the list of 

candidate species. We intend any listing 

action for the species to be as accurate 

as possible by reflecting the best 

available information. Therefore, we 

will continue to accept additional 

information and comments on the status 

of and threats to this species from all 

concerned governmental agencies, the 

scientific community, industry, or any 

other interested party concerning this 

finding. If an emergency situation 

develops that warrants an emergency 

listing of this species, we will act 

immediately to provide additional 

protection. 

References 

A complete list of all references cited 

herein is available upon request from 

the Western Colorado Field Office (see 

ADDRESSES). 

Author 

The primary authors of this document 

are staff located at the Colorado Field 

Office (see ADDRESSES). 

Authority 

The authority for this action is the 

Endangered Species Act of 1973, as amended 

(16 U.S.C. 1531 et seq.). 

Dated: January 29, 2008. 

H. Dale Hall, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 08–493 Filed 2–4–08; 8:45 am] 

BILLING CODE 4310–55–P 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[FWS–R8–ES–2008–0014; 92210–1117–

0000–B4] 

RIN 1018–AV05 

Endangered and Threatened Wildlife 

and Plants; Designation of Critical 

Habitat for the Sierra Nevada Bighorn 

Sheep (Ovis canadensis californiana) 

and Proposed Taxonomic Revision 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Proposed rule; reopening of 

comment period, notice of availability 

of draft economic analysis, and 

amended required determinations. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce the 

reopening of the public comment period 

on the proposed designation of critical 

habitat for the Sierra Nevada bighorn 

sheep (Ovis canadensis californiana) 

and proposed taxonomic revision under 


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