60516 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS-R8-ES-2007-0022] 

[MO 92210-0-0008-B2] 

Endangered and Threatened Wildlife 

and Plants; 12-Month Finding on a 

Petition to List the Pygmy Rabbit as 

Endangered or Threatened 

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 a 

12–month finding on a petition to list 

the pygmy rabbit (Brachylagus 

idahoensis) as endangered or threatened 

under the Endangered Species Act of 

1973, as amended. After review of all 

available scientific and commercial 

information, we find the listing of the 

pygmy rabbit is not warranted at this 

time. However, we ask the public to 

submit to us any new information that 

becomes available concerning the 

threats to the pygmy rabbit or its habitat 

at any time. 

DATES: The finding announced in the 

document was made on September 30, 

2010. 

ADDRESSES: This finding is available on 

the Internet at http:// 

www.regulations.gov at Docket Number 

FWS-R8-ES-2007-0022. 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, 1340 Financial 

Boulevard, Suite 234, Reno, NV 89502. 

Please submit any new information, 

materials, comments, or questions 

concerning this species to the Service at 

the above street address. 

FOR FURTHER INFORMATION CONTACT: 

Robert D. Williams, State Supervisor, 

U.S. Fish and Wildlife Service, Nevada 

Fish and Wildlife Office (see 

ADDRESSES); by telephone (775) 861- 

6300 or by facsimile (775) 861-6301. 

Persons who use a telecommunications 

device for the deaf (TDD) may call the 

Federal Information Relay Service 

(FIRS) at (800) 877-8339. 

SUPPLEMENTARY INFORMATION: 

Background 

Section 4(b)(3)(B) of the Endangered 

Species Act of 1973, as amended (Act) 

(16 U.S.C. 1531 et seq.), requires that, 

for any petition to revise the List of 

Endangered and Threatened Wildlife 

and Plants that contains substantial 

scientific or commercial information 

that the listing may be warranted, we 

make a finding within 12 months of the 

date of the receipt of the petition. In this 

finding, we will determine that the 

petitioned action is either: (1) Not 

warranted, (2) warranted, or (3) 

warranted, but the immediate proposal 

of a regulation implementing the 

petitioned action is precluded by other 

pending proposals to determine whether 

species are endangered or threatened , 

and 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 November 21, 1991, we added the 

pygmy rabbit to our list of candidate 

species as a category 2 candidate species 

(56 FR 58804). A category 2 candidate 

species was a species for which we had 

information indicating that a proposal to 

list it as threatened or endangered under 

the Act may be appropriate, but for 

which additional information on 

biological vulnerability and threat was 

needed to support the preparation of a 

proposed rule. In the February 28, 1996, 

Candidate Notice of Review (CNOR) (61 

FR 7595), we adopted a single category 

of candidate species defined as follows: 

‘‘Those species for which the Service 

has on file sufficient information on 

biological vulnerability and threat(s) to 

support issuance of a proposed rule to 

list but issuance of the proposed rule is 

precluded.’’ In previous CNORs, species 

matching this definition were known as 

category 1 candidates for listing. Thus, 

the Service no longer considered 

category 2 species as candidates and did 

not include them in the 1996 or any 

subsequent CNORs. The decision to stop 

considering category 2 species as 

candidates was designed to reduce 

confusion about the status of these 

species and to clarify that we no longer 

regarded these species as candidates for 

listing. 

On April 21, 2003, we received a 

petition dated April 1, 2003, from the 

Committee for the High Desert, Western 

Watersheds Project, American Lands 

Alliance, Oregon Natural Desert 

Association, Biodiversity Conservation 

Alliance, Center for Native Ecosystems, 

and Mr. Craig Criddle requesting the 

pygmy rabbit found in Oregon, Idaho, 

Montana, Wyoming, California, Nevada, 

and Utah be listed as endangered or 

threatened in accordance with section 4 

of the Act (Committee for the High 

Desert et al. 2003, entirety). The petition 

was clearly identified as a petition and 

contained the names, signatures, and 

addresses of the requesting parties. The 

petitioners requested designation of 

critical habitat concurrent with the 

listing. Included in the petition was 

supporting information regarding the 

species’ taxonomy and ecology, 

historical and current distribution, and 

perceived threats to the pygmy rabbit. 

On June 10, 2003, we acknowledged 

in a letter the receipt of the petition and 

stated we determined an emergency 

listing was not warranted for the pygmy 

rabbit. We also stated if our ongoing 

status review of the species indicates 

that an emergency listing is warranted, 

we would act accordingly. In addition, 

we advised the petitioners that we 

would not be able to process the 

petition in a timely manner. On May 3, 

2004, we received a 60–day notice of 

intent to sue, and on September 1, 2004, 

we received a complaint regarding our 

failure to carry out the 90–day and 12– 

month findings on the status of the 

pygmy rabbit. On March 2, 2005, we 

reached an agreement with the plaintiffs 

to submit to the Federal Register a 

completed 90–day finding by May 16, 

2005, and to complete, if applicable, a 

12–month finding by February 15, 2006 

(Western Watersheds Project et al. v. 

U.S. Fish and Wildlife Service (CV-04- 

0440-N-BLW) (D. Idaho). 

On May 20, 2005, we published a 90– 

day finding in the Federal Register (70 

FR 29253) stating that the petition did 

not present substantial information 

indicating that listing the pygmy rabbit 

may be warranted. On March 28, 2006, 

we received a complaint regarding 

alleged violations of the Act and the 

Administrative Procedure Act with 

regard to our May 20, 2005, 90–day 

finding (Western Watersheds Project et 

al. v. Gale Norton and U.S. Fish and 

Wildlife Service (CV 06-CV-00127-S-EJL) 

(D. Idaho)). On September 26, 2007, the 

court issued an order remanding our 

May 20, 2005, 90–day finding and 

required the Service to issue a new 90– 

day finding on or before December 26, 

2007. On January 8, 2008, we published 

a new 90–day finding (73 FR 1312), and 

determined that the petition presented 

substantial information indicating that 

the petitioned action may be warranted. 

Additionally in that notice, we 

indicated that we would be initiating a 

status review of the pygmy rabbit and 

opening a 60–day public comment 

period. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60517 

This finding does not address our 

prior listing of the Columbia Basin 

distinct population segment (DPS) of the 

pygmy rabbit which occurs in the State 

of Washington. On November 30, 2001, 

we published an emergency listing and 

concurrent proposed rule to list this 

DPS of the pygmy rabbit as endangered 

(66 FR 59734 and 66 FR 59769, 

respectively). We listed the Columbia 

Basin DPS of the pygmy rabbit as 

endangered in our final rule dated 

March 5, 2003 (68 FR 10388). This 

finding addresses the petitioned action 

that requests listing of the pygmy rabbit 

as endangered or threatened in the 

remainder of its range in Oregon, Idaho, 

Montana, Wyoming, California, Nevada, 

and Utah. 

Species Information 

Species Description 

The pygmy rabbit is the smallest 

North American Leporid. Adult weights 

range from 0.54 to 1.2 pounds (245 to 

553 grams); adult lengths range from 9.1 

to 12.1 inches (in) (23.1 to 30.7 

centimeters (cm)) (Dice 1926, p. 28; 

Grinnell et al. 1930, p. 554; Bailey 1936, 

p. 110; Orr 1940, p. 194; Janson 1946, 

pp. 21, 23; Durrant 1952, p. 88; Ingles 

1965, p. 143; Bradfield 1974, pp. 10-11; 

Holt 1975, pp. 125-126; Campbell et al. 

1982, p. 100). Adult females are 

generally larger than adult males. The 

species can be distinguished from other 

rabbits by its small size, gray color, 

short rounded ears, small hind legs, and 

the absence of white on the tail (66 FR 

59734). 

Taxonomy 

The pygmy rabbit is a member of the 

family Leporidae, which includes 

rabbits and hares. This species has been 

placed in various genera positions since 

its type specimen was described in 1891 

by Merriam (1891, pp. 76-78), who 

classified the ‘‘Idaho pygmy rabbit’’ as 

Lepus idahoensis. Currently, the pygmy 

rabbit is generally placed within the 

monotypic genus Brachylagus and 

classified as B. idahoensis (Green and 

Flinders 1980a, p. 1; Washington 

Department of Fish and Wildlife 

(WDFW) 1995, p. 1); this is the 

taxonomy accepted by the Service. The 

analysis of blood proteins (Johnson 

1968, cited in WDFW 1995, p. 1) 

suggests that the pygmy rabbit differs 

greatly from species within both the 

Lepus and Sylvilagus genera. Halanych 

and Robinson (1997, p. 301) supported 

the separate generic status as 

Brachylagus for the pygmy rabbit based 

on phylogenetic position and sequence 

divergence values. The pygmy rabbit 

has no recognized subspecies (Grinnell 

et al. 1930, p. 555; Davis 1939, p. 364; 

Larrison 1967, p. 64; Green and Flinders 

1980a, p. 1; Janson 2002, p. 4). 

Ecology and Life History 

Pygmy rabbits are typically found in 

areas of tall, dense Artemisia spp. 

(sagebrush) cover and are considered a 

sagebrush obligate species because they 

are highly dependent on sagebrush to 

provide both food and shelter 

throughout the year (Dice 1926, p. 27; 

Grinnell et al. 1930, p. 553; Orr 1940, 

pp. 194-197; Hall 1946, p. 615; Janson 

1946, pp. 39-40, 53; Wilde 1978, p. 46; 

Green and Flinders 1980a, pp. 1-3 and 

b, pp. 137-141; Weiss and Verts 1984, 

pp. 569-570; Katzner et al. 1997, p. 

1,053). Anthony (1913, p. 22) also 

mentioned he found pygmy rabbits in 

‘‘little draws and flats’’ in Oregon, where 

the tall sagebrush was thick and where 

Chrysothamnus spp. (rabbit brush) grew 

in extensive patches, and occasionally 

they were found on ‘‘sparsely brushed 

flats and hills.’’ 

The winter diet of pygmy rabbits is 

composed of up to 99 percent sagebrush 

(Wilde 1978, p. 46; Green and Flinders 

1980b, p. 138), which is unique among 

leporids (rabbits and hares) (White et al. 

1982, p. 107). During spring and 

summer in Idaho, their diet consists of 

approximately 51 percent sagebrush, 39 

percent grasses (particularly native 

bunch-grasses, such as Agropyron spp. 

and Poa spp.), and 10 percent forbs 

(Green and Flinders 1980b, p. 138). 

There is evidence that pygmy rabbits 

preferentially select native grasses as 

forage over other available foods during 

this period. In addition, total grass cover 

relative to forbs and shrubs may be 

reduced within the immediate areas 

occupied by pygmy rabbits as a result of 

their use during spring and summer 

(Green and Flinders 1980b, pp. 138- 

141). The specific diets of pygmy rabbit 

likely vary by region (68 FR 10388). 

Pygmy rabbits may be active at any 

time of the day or night, and appear to 

be most active during mid-morning 

(Anthony 1913, p. 23; Bailey 1936, p. 

111; Bradfield 1974, pp. 14-15; Green 

and Flinders1980a, p. 3; Gahr 1993, pp. 

45-46). Flinders et al. (2005, p. 27) 

found pygmy rabbits to be 72 percent 

more active during twilight. Larrucea 

(2007, p. 79) found pygmy rabbits were 

most active during dawn and dusk (a 

bimodal diel activity pattern). Activity 

at dawn was greatest except for during 

winter when dusk activity was higher. 

Lee (2008, p. 33) found pygmy rabbits 

were active during all time periods of 

the day, but the greatest activity 

occurred at night. 

Pygmy rabbits maintain a low stance, 

have a deliberate gait, and are relatively 

slow and vulnerable in more open areas. 

They can evade predators by 

maneuvering through the dense shrub 

cover of their preferred habitats, often 

along established trails, or by escaping 

among their burrows (Anthony 1913, 

pp. 22-23; Bailey 1936, p. 111; Severaid 

1950, p. 3; Bradfield 1974, pp. 26-27). 

Due to their small size, behavior, and 

habitat, these small rabbits can be easily 

overlooked (Merriam 1891, p. 75; 

Grinnell et al. 1930, p. 553; Janson 1940, 

p. 1; Severaid 1950, p. 3; Holt 1975, p. 

135; Janson 2003, p. 71). 

The pygmy rabbit is one of only two 

rabbits in North America that digs its 

own burrows (Nelson 1909, p. 22; Bailey 

1936, p. 111; Hall 1946, p. 617; Janson 

1946, p. 43; Bradfield 1974, p. 28; Wilde 

1978, p. 17). Pygmy rabbit burrows are 

typically found in relatively deep, loose 

soils of wind-borne or water-borne (e.g., 

alluvial fan) origin. Pygmy rabbits, 

especially juveniles, likely use their 

burrows as protection from predators 

and inclement weather (Bailey 1936, p. 

111; Bradfield 1974, pp. 26-27). Some 

burrows have only one entrance. Others 

have multiple entrances, some of which 

are concealed at the base of larger 

sagebrush plants (Dice 1926, p. 27). A 

single entrance burrow may be referred 

to as a ‘‘burrow’’ while single entrance 

burrows, multi-entrance burrows, or an 

entire site may be referred to as a 

‘‘burrow system’’. Burrows are relatively 

simple and shallow, often no more than 

2.2 yards (yd) (2 meters (m)) in length 

and usually less than 1.1 yd (1 m) deep 

with no distinct chambers (Bailey 1936, 

p. 111; Bradfield 1974, pp. 29-30; Green 

and Flinders 1980a, p. 2; Gahr 1993, p. 

63). Burrows are typically dug into 

gentle slopes or mound or inter-mound 

areas of more level or dissected 

topography (Wilde 1978, p. 26; Gahr 

1993, pp. 77-80). 

In general, the number of active 

burrows in an area increases over the 

summer as the number of juveniles 

increase. However, the number of active 

burrows may not be directly related to 

the number of individuals in a given 

area because some individual pygmy 

rabbits appear to maintain multiple 

burrows and some individual burrows 

are used by multiple individuals (Janson 

1940, p. 21; Janson 1946, p. 44; Gahr 

1993, pp. 66, 68; Heady 1998, p. 25). 

Pygmy rabbits may also be using more 

than one burrow or burrow system at a 

specific time or during different times of 

the year (Purcell 2006, p. 96). In Idaho, 

Sanchez and Rachlow (2008, p. 1306) 

found the number of burrows used by 

individuals increased with home range 

size. Patterns of burrow system use 

varied by study area, sex, and season 

(Sanchez and Rachlow 2008, pp. 1306- 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60518 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

1307). Larrucea (2007, pp. 96-97) found 

annual and intra-annual changes at 

three study sites during a 3–year period 

in the Reese River Valley, Nevada. 

During two of the three years, one site 

showed lack of activity during winter 

and spring. Pygmy rabbits returned to 

this site in June and many new burrows 

were found. This site may have been 

marginal habitat and rabbits using the 

area in June may have been dispersing 

juveniles from other areas. At the other 

two sites where pygmy rabbits were 

observed year-round, the fewest active 

burrows were found from July to 

October. With the return of cooler 

weather in the fall, the number of active 

burrows again increased. Many of these 

new active burrows were ones that had 

previously been inactive or collapsed. 

Flinders et al. (2005, p. 25) reported 

distances between burrow systems. 

They found burrow systems with 

multiple entrances averaged 124.6 yd 

(114.0 m) away from the next nearest 

multiple entrance system, while 

distances between systems with 

multiple entrances to single entrance 

burrows averaged 57.1 yd (52.2 m) 

away. Single entrance burrow systems 

averaged 14 yd (12.8 m) away from the 

nearest single entrance system. 

Pygmy rabbits occasionally make use 

of burrows abandoned by other species, 

such as the yellow-bellied marmot 

(Marmota flaviventris), badger (Taxida 

taxus), or Utah prairie dog (Cynomys 

parvidens) (Borell and Ellis 1934, p. 41; 

Hall 1946, p. 617; Bradfield 1974, p. 28; 

Green and Flinders 1980a, p. 2; Flinders 

et al. 2005, p. 30). As a result, they may 

occur in areas of shallower or more 

compact soils that support sufficient 

shrub cover (Bradfield 1974, p. 29). 

Natural cavities (such as holes in 

volcanic rock), rock piles, stone walls, 

and areas around abandoned buildings 

may also be used (Janson 1946, pp. 44- 

46). During winter, pygmy rabbits make 

extensive use of snow burrows, possibly 

for access to sagebrush forage (Bradfield 

1974, p. 17; Katzner and Parker 1997, p. 

1,069), as travel corridors among their 

underground burrows, for protection 

from predators, and/or as thermal cover 

(Katzner and Parker 1997, pp. 1,063, 

1,069-1,070). 

Pygmy rabbits tend to have relatively 

small home ranges during winter, 

remaining within 98 ft (30 m) of their 

burrows (Janson 1946, p. 75). Bradfield 

(1974, p. 20), Katzner and Parker (1997, 

p. 1,066), and Flath and Rauscher (1995, 

p. 3) found pygmy rabbit tracks in snow 

indicating movements of 262 to 328 ft 

(80 to 100 m) or more from their 

burrows. They have larger home ranges 

during spring and summer (Janson 1946, 

p. 75; Gahr 1993, pp. 103-105). During 

the breeding season in Washington, 

females tend to make relatively short 

movements within a small core area and 

have home ranges covering roughly 6.7 

acres (ac) (2.7 hectares (ha)); males tend 

to make longer movements, traveling 

among a number of females, resulting in 

home ranges covering roughly 49.9 ac 

(20.2 ha) (Gahr 1993, p. 118). Katzner 

(1994, pp. 14-15) found home range size 

extremely variable in Wyoming; home 

ranges were from 0.12 to 0.86 ac (0.05 

to 0.35 ha) for females and 0.82 to 4.4 

ac (0.33 to 1.8 ha) for males. Burak 

(2006, p. 22) found in Owyhee County, 

Idaho, that pygmy rabbit home range 

sizes based on Minimum Convex 

Polygons differed between the sexes and 

ranged from 49.9 to 69.7 ac (20.2 to 28.2 

ha) for males and from 4 to 5.4 ac (1.6 

to 2.2 ha) for females during the 

breeding season. Crawford (2008, p. 47) 

found that pygmy rabbit annual home 

ranges in southeastern Oregon and 

northwestern Nevada differed between 

the sexes and ranged from 1.2 to 25.8 ac 

(0.49 to 10.46 ha) for males and 0.27 to 

18.7 ac (0.11 to 7.55 ha) for females. 

During the breeding season, home 

ranges for males ranged from 0.27 to 

18.5 ac (0.11 to 7.49 ha) and from 0.15 

to 17.5 ac (0.06 to 7.10 ha) for females. 

Sanchez and Rachlow (2008, p. 1307) 

in Idaho found range use between 

consecutive seasons and between 

seasons over 2 years was highly 

variable; some pygmy rabbits shifted 

seasonal ranges markedly, but most 

ranges showed overlap between seasons 

and years. One male shifted his range 

center by 8,013.9 yd (7,332 m), but other 

males shifted their range centers 

between 33 and 122 yd (30 and 112 m). 

Females shifted their range centers 

between 58 and 144 yd (53 and 132 m) 

(Sanchez and Rachlow 2008, p. 1307). 

Distances shifted between like seasons 

over the 2 years were similar to those 

observed between consecutive seasons. 

Males showed a distance shift of 

between 47 and 269 yd (43 and 246 m) 

and females showed a shift of between 

0 and 150 yd (0 and 137 m) (Sanchez 

and Rachlow 2008, p. 1307). 

Earlier reports indicated pygmy 

rabbits were known to have traveled up 

to 0.75 mile (mi) (1.2 kilometers (km)) 

from their burrows (Gahr 1993, p. 108), 

and there are a few records of 

individuals moving up to 2.17 mi (3.5 

km) (Green and Flinders 1979, p. 88; 

Katzner and Parker 1998, p. 73). 

Rauscher (1997, p. 5) reported that 

pygmy rabbits crossed 500 yd (457.2 m) 

of relatively open grassland habitat to 

reach a sagebrush stringer in Montana. 

Katzner (1994, p. 105) accounted for all 

the rabbits within a range of 0.62 mi (1 

km) of his study area. When pygmy 

rabbits not previously observed 

appeared, he concluded these 

individuals must have traveled a 

‘‘considerable distance.’’ More recently, 

Estes-Zumpf and Rachlow (2009, p. 367) 

radio-tagged juvenile pygmy rabbits in 

Idaho and found median dispersal 

movements of 0.93 mi (1.5 km) and 3.9 

mi (6.2 km) and maximum dispersal 

movements of 4.0 mi (6.5 km) and 7.4 

mi (11.9 km) by male and female 

rabbits, respectively. Burak (2006, p. 27) 

indicated the maximum distance a male 

pygmy rabbit moved was 1,662.5 yd 

(1,521 m) and 1,112.7 yd (1,018 m) for 

a female. Crawford (2008, p. 54) in 

Nevada and Oregon reported that 24 

radio-marked rabbits moved greater than 

0.3 mi (0.5 km) with a maximum longdistance movement of 5.3 mi (8.5 km) 

recorded by a juvenile female. Twentyone of the individuals that traveled 

greater than 0.3 mi (0.5 km) were 

juveniles. 

Pygmy rabbits may begin breeding the 

year following their birth (Wilde 1978, 

pp. 64-66, 127; Fisher 1979, p. 13). In 

some parts of the species’ range, females 

may have up to three litters per year and 

average six young per litter (Davis 1939, 

p. 365; Hall 1946, p. 618; Janson 1946, 

pp. 67-69; Green 1978, pp. 35-36; Wilde 

1978, p. 69). Breeding appears to be 

highly synchronous in a given area and 

juveniles are often identifiable to 

cohorts (Wilde 1978, pp. 69-70). Prior to 

publication of a study in 2005, no 

evidence of nests, nesting material, or 

lactating females with young had been 

found in burrows (Bailey 1936, p. 111; 

Janson 1940, p. 23; Janson 1946, p. 69; 

Bradfield 1974, p. 29; Gahr 1993, p. 82 

Rauscher 1997, p. 11). Recent studies 

have found that natal burrows are 

constructed by pygmy rabbits. Rachlow 

et al. (2005, pp. 137-138) provide 

information on seven natal burrows 

found in Lemhi Valley, Idaho. Females 

were observed digging and subsequently 

back-filling burrows with soil. Fine 

grasses, shredded sagebrush bark, and 

hair were the primary components used 

in the nesting material. Larrucea (2007, 

pp. 89-90) found three natal burrows in 

Reese River Valley, Nevada, but did not 

describe them. Burak (2006, p. 29) 

found female pygmy rabbits construct 

natal burrows outside of their original 

home range core area. Three of the four 

natal burrows he found were located 

outside of the core area; the fourth 

female stayed within a second core area 

that included the natal burrow and 

when the burrow became inactive, she 

returned to her original core area (Burak 

2006, p. 29). Individual juveniles have 

been found under clumps of sagebrush, 

although it is not known if they are 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60519 

routinely hidden at the bases of 

scattered shrubs or within burrows 

(Wilde 1978, p. 115). 

A wide range of pygmy rabbit 

population densities has been reported. 

Janson (1946, p. 84) reported estimated 

pygmy rabbit densities of 0.75 to 1.75 

per ac (1.9 to 4.3 per ha) and 3.5 pygmy 

rabbits per ac (8.6 per ha) in Utah. 

Flinders et al. (2005, p. 16) reported 0.3 

rabbits per ac (0.79 rabbits per ha) in 

Grass Valley, Utah. Green (1978, p. 62) 

reported an estimate of 18.2 pygmy 

rabbits per ac (45 per ha) in Idaho. In 

Montana, Rauscher (1997, p. 10) 

estimated pygmy rabbit density as 0.67 

rabbits per burrow or 1.2 per ac (3.0 per 

ha). Based on fecal dropping counts, 

Larsen et al. (2006, pp. 26-27) estimated 

rabbit density in Deep Creek watershed, 

Utah, as 0.07 per ac (0.17 rabbits per 

ha). Using line transects in Wyoming, 

Purcell (2006, pp. 100, 105) reported a 

range of burrow systems per mi (km) for 

systematic transects (1.7 to 18.2 per mi, 

2.7 to 29.3 per km) and random 

transects (0.8 to 7.4 per mi, 1.33 to 11.97 

per km) in 10 study areas. Larrucea 

(2007, p. 89) estimated, using transect 

counts, that the relative density at five 

study areas in California and Nevada 

ranged from 0.4 to 1.7 rabbits per ac (0.9 

to 4.2 rabbits per ha). 

The annual mortality rate of adult 

pygmy rabbits may be as high as 88 

percent, and more than 50 percent of 

juveniles can die within roughly 5 

weeks of their emergence (Wilde 1978, 

pp. 139-140). Estes-Zumpf and Rachlow 

(2009, p. 367) found mortality rates 

were 69.2 percent and 88.5 percent for 

male and female juvenile pygmy rabbits, 

respectively, in their study area in eastcentral Idaho. The mortality rate was 

highest within two months of emerging 

from the natal burrow. However, the 

mortality rates of adult and juvenile 

pygmy rabbits can vary considerably 

between years, and even between 

juvenile cohorts within years (Wilde 

1978, pp. 85-95, 138-140). Predation is 

the main cause of pygmy rabbit 

mortality (Green 1979, p. 25). Sanchez 

(2007, pp. 90-91) attributed 42 percent 

of natural mortalities to mammalian and 

avian predation. She was unable to 

determine the cause of death in 58 

percent of the mortalities. 

Predators of the pygmy rabbit include 

badgers, long-tailed weasels (Mustela 

frenata), coyotes (Canis latrans), bobcats 

(Felis rufus), great horned owls (Bubo 

virginianus), long-eared owls (Asio 

otus), ferruginous hawks (Buteo regalis), 

northern harriers (Circus cyaneus), and 

common ravens (Corvus corax) (Borell 

and Ellis 1934, p. 42; Janson 1946, pp. 

89-90; Gashwiler et al. 1960, p. 227; 

Green 1978, p. 37; Wilde 1978, pp. 96, 

141-143; Johnson and Hanson 1979, p. 

952; WDFW 1995, p. 6). 

Sanchez (2007, p. 92) estimated that 

for known-aged rabbits, the average 

lifespan was 1.16 years. For rabbits 

captured as adults, assuming a birth 

date of May 1 of the previous year, 

estimated average life expectancy was 

1.7 years, and the maximum lifespan 

achieved was 3.3 years. 

Population cycles are not known in 

pygmy rabbits, although local, relatively 

rapid population declines have been 

noted in some States (Janson 1946, p. 

84; Bradfield 1974, p. 39; Weiss and 

Verts 1984, p. 569). Janson (2003, p. 71) 

remarked that pygmy rabbits likely 

undergo local, if not regional, 

fluctuations. After initial declines, 

pygmy rabbit populations may not have 

the same capacity for rapid increases in 

numbers in response to favorable 

environmental conditions as compared 

to other rabbit species. This may be due 

to their close association with specific 

components of sagebrush ecosystems, 

and the relatively limited availability of 

their preferred habitats (Wilde 1978, p. 

145; Green and Flinders 1980b, p. 141; 

WDFW 1995, p. 13). No study has 

documented rapid increases in pygmy 

rabbit numbers in response to 

environmental conditions (Gabler 1997, 

p. 95). Long-term population monitoring 

studies are not available indicating 

whether population fluctuations or 

cycles occur for pygmy rabbits or if 

seasonal or other habitat shifts or 

movements have been misinterpreted as 

declines. 

Literature indicates that pygmy 

rabbits have never been evenly 

distributed across their range (Bailey 

1936, p. 111; Janson 1940 p. 5; Holt 

1975, pp. 133-134). While the species 

occurs throughout most of the Great 

Basin, they exhibit extremely 

specialized habitat requirements, and 

thus occupy only a small subset of 

locations within this range (Larrucea 

2007, p. 2). They are found in areas 

within their broader distribution where 

sagebrush cover is sufficiently tall and 

dense, and where soils are sufficiently 

deep and loose to allow burrowing 

(Bailey 1936, p. 111; Green and Flinders 

1980a, p. 2; Campbell et al. 1982, p. 100; 

Weiss and Verts 1984, p. 563; WDFW 

1995, p. 15). Sagebrush- dominated 

communities are naturally subject to 

disturbances of various kinds resulting 

in a heterogeneous distribution of 

different stand sizes and age classes, 

and on the landscape scale, pygmy 

rabbit distribution is naturally disjunct 

(Himes and Drohan 2007, p. 380). Local 

distribution of this habitat and thus 

pygmy rabbit populations likely shift 

over time due to natural and human 

disturbances including fire, agriculture 

production, flooding, grazing, and 

weather patterns (Keinath and McGee 

2004, p. 5). In the past, dense vegetation 

along permanent and intermittent 

stream corridors, alluvial fans, and 

sagebrush plains probably provided 

travel corridors and dispersal habitat for 

pygmy rabbits between suitable use 

areas (Green and Flinders 1980a, p. 1; 

Weiss and Verts 1984, p. 570; WDFW 

1995, p. 15). Since European settlement 

of the western United States, dense 

vegetation associated with human 

activities (fence rows, roadway 

shoulders, borrow ditches, crop 

margins, abandoned fields) may have 

also acted as avenues of dispersal 

between local populations of pygmy 

rabbits (Green and Flinders 1980a, p. 1; 

Rauscher 1997, p. 16). 

Distribution, Abundance, and Trends 

The pygmy rabbit’s general historical 

and current geographic range, excluding 

the Columbia Basin DPS, includes most 

of the Great Basin and some of the 

adjacent intermountain areas of the 

western United States (Green and 

Flinders 1980a, p. 1), and the 

boundaries can be described as follows: 

the northern boundary extends into 

southeastern Oregon and southern 

Idaho. The eastern boundary extends 

into southwestern Montana and south 

central Wyoming. The southeastern 

boundary extends into southwestern 

Utah. Central Nevada and eastern 

California provide the southern and 

western boundaries (Merriam 1891, p. 

75; Nelson 1909, p. 275; Grinnell et al. 

1930, pp. 553, 558; Bailey 1936, pp. 

110-111; Janson 1946, pp. 32-33; 

Campbell et al. 1982, p. 100; WDFW 

1995, pp. 1-2, Purcell 2006, pp. 1, 7-11, 

30). Based on available information, the 

current distribution of the pygmy rabbit 

indicates a possible range contraction in 

northern California (Larrucea and 

Brussard 2008a, p. 696). Because 

uncertainty remains about whether this 

possible range contraction has occurred 

due to limited survey efforts in northern 

California both historically and recently, 

it is not shown in Figure 1. Figure 1 

illustrates the approximate historical 

and current range of the pygmy rabbit in 

the seven States discussed in this 

finding. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60520 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Figure 1. Approximate historical and 

current range (based on data from 1877 

to 2008) of the pygmy rabbit 

(Brachylagus idahoensis) not including 

the Columbia Basin DPS in Washington 

State. 

To determine the historical and 

current distribution and trend analysis 

for pygmy rabbits across the seven 

States discussed in this finding, we 

reviewed published scientific peerreviewed literature; unpublished agency 

documents; dissertations; theses; 

databases maintained by State heritage 

programs, State wildlife agencies, and 

Federal agencies; survey data sheets; 

museum records; electronic mail 

records; and agency notes to the files. 

Older published literature (prior to the 

mid to late 1990’s) generally focused on 

the species’ life history, behavior, and 

some habitat relationships and provided 

location information of study areas. 

More recent unpublished literature 

(since the mid to late 1990’s to 2008) 

has been primarily related to surveys 

conducted by government agencies or 

their consultants and universities to 

determine pygmy rabbit occurrence 

within portions of a State and some 

information regarding species’ life 

history, behavior, and habitat 

relationships. Survey efforts have 

focused on location of pygmy rabbit 

signs rather than on documenting 

known or perceived threats to the 

species at these sites. Rarely has 

revisiting of sites occurred with the 

purpose of monitoring populations over 

time. While we consider this 

information of limited use to our finding 

due to its local, short-term nature, it is 

the best scientific information available 

to conduct our analysis. 

We compiled a database of records 

(location points) of various pygmy 

rabbit signs for each State from these 

various data sources listed above. Some 

records were not entered into a State 

database if adequate information was 


jdjones on DSK8KYBLC1PROD with PROPOSALS2EP30SE10.008</GPH>
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60521 

not provided (e.g., we could not 

determine a location point because the 

source map did not indicate location or 

survey data sheet location point 

information was unreadable). Once each 

State database was compiled, we 

reviewed each location point and 

eliminated its database record if it was 

not determined to be a reliable data 

point as discussed below. The final 

databases combined contain 

approximately 68 percent of all the 

location points compiled. We consider 

the location point data retained in these 

seven State databases to be the best 

scientific information available. We will 

refer to these created State databases as 

the Service’s databases. 

We are aware of concerns related to 

the use of anecdotal occurrence records 

to determine distribution of species 

(McKelvey et al. 2008, pp. 549-554). We 

are also aware of confidence levels 

related specifically to pygmy rabbit 

presence and level of activity at 

particular sites due to various factors 

(e.g., sighting of targeted species vs. 

only targeted species sign or potential 

targeted species sign observed; if burrow 

activity is uncertain, the site should be 

revisited; uncertainties due to other 

species or other rabbit species using 

burrows; pellets being misidentified) 

(Bartels 2003, pp. 47-49; Keinath and 

McGee 2004, pp. 32-34). 

As a result of these concerns, we have 

based our analysis on what we 

considered to be the more reliable 

records indicating pygmy rabbit 

presence and activity level. The 

following types of records were not 

included in the Service’s databases for 

our analysis: database records that 

showed some level of uncertainty for 

the information being provided (e.g., 

other leporid species data included; 

uncertainty about whether pygmy rabbit 

was observed or other leporid species; 

using words such as ‘‘possible’’, 

‘‘potential’’, ‘‘maybe’’, ‘‘unsure’’); records 

that only provided location data or 

indicated pygmy rabbit sign with no 

additional information indicating what 

type of sign (e.g., burrow, pellet, track, 

sighting of animal as relates to 

reliability) had been observed; records 

related to telemetry locations (while 

informative in determining an 

individual’s distribution within its 

home range, this provides little 

information at the larger landscape scale 

used here; we did include the capture 

location of any individual pygmy rabbit 

trapped and fitted with a tradio collar); 

records based solely on pellets or tracks 

due to concerns with species 

misidentification; those lacking key 

information (e.g., year which is needed 

for trend analysis) and duplicate 

records. 

For our analysis, we mapped records 

of ‘‘active’’ sites or burrows defined as 

those database records that indicated an 

activity level (at the time of the survey) 

of current, present, occupied, active, or 

recently active burrows; burrows in 

combination with fresh pellets; a visual 

sighting; photographic evidence; fecal 

DNA confirmation; specimen collected; 

trapping effort; in combination with 

tracks; or any combination thereof. All 

sighting records were included in our 

analysis even if no other information 

was provided, unless uncertainty was 

expressed about whether it had been a 

pygmy rabbit observed or another 

leporid species. 

We also mapped records of ‘‘inactive’’ 

sites or burrows defined as those 

database records that indicated an 

activity level (at the time of the survey) 

of inactive, not recent, old, very old, 

collapsed, or burrow plus old pellets. In 

addition, we assumed ‘‘inactive’’ for site 

or burrow records that did not provide 

a status and did not provide information 

to support a determination of active, 

those with an ‘‘undetermined’’ activity 

status, or were unclear. We reviewed the 

mapped distribution for the ‘‘active’’ and 

‘‘inactive’’ site categories across each 

State. 

In addition, we mapped database 

records of ‘‘absent’’ areas defined as 

points where no sign of pygmy rabbit 

occupancy was evident. Most databases 

do not include records of areas surveyed 

but where no pygmy rabbit sign was 

observed. We believe this type of 

information can be valuable; however, 

we do not assume that pygmy rabbits 

were or should have been present in 

areas where they were determined to be 

absent. It is possible that an area is 

unsuitable for pygmy rabbits while 

appearing suitable to surveyors. 

Conversely, it is possible an area that 

appears unsuitable to surveyors for 

pygmy rabbits may actually be so 

(Ulmschneider et al. 2004, pp. 2-3). On 

the ground surveying is necessary to 

positively indicate pygmy rabbit 

occupancy (Bartels 2003, pp. 92-94; 

Lenard et al. 2005, p. 1; Meisel 2006, pp. 

26, 48). The ‘‘absent’’ information 

indicates locations where survey efforts 

were conducted but pygmy rabbit sign 

was not evident. Limited ‘‘absent’’ 

information was obtained for the States 

of Oregon, California, Nevada, and 

Wyoming. 

During our analysis we encountered 

some difficulties in adapting data 

collected for another’s purpose for our 

species’ status review, and there were 

several limitations. Overall, survey 

information collected over the years 

reflects different surveyors, different 

survey methods, different levels of 

survey intensity, and different amounts 

and types of information recorded. We 

generally accepted the information 

indicated in a report, data sheet, or 

database and tried to do as little 

interpretation as possible. For some 

locations, we replaced locational 

descriptions (Township, Range and 

Section or a narrative description) with 

Universal Transverse Mercator (UTM) 

coordinates or a center point for a 

section surveyed or a point was buffered 

to indicate an approximate location. For 

a portion of records from Oregon, we 

created a point representing the center 

of a study area and ‘‘active’’ and 

‘‘inactive’’ burrows were separated. 

We encountered some difficulties 

with interpreting data provided under 

different reporting techniques. In 

general, most surveys for pygmy rabbits 

report location information in terms of 

point data (i.e., legal description or 

Global Positioning System (GPS)) with 

qualifiers or descriptions for sign, such 

as burrows (present, absent), activity 

level (occupied, unoccupied, active, 

inactive, current, recent, old, very old), 

pellets (fresh, old), sightings (actual 

sightings of pygmy rabbits, specimen 

collection, capture, photographic 

record), and tracks. Some surveyors 

developed their own rating system or 

confidence level for burrow or site 

activity (Purcell 2006, p. 38; Himes and 

Drohan 2007, p. 375; Flinders et al. 

2005, pp. 8-9). Some efforts reported 

only those sites that were considered 

positive (confirmed with photographic 

evidence), active, or occupied sites and 

did not include information for areas 

considered inactive or unoccupied. 

Location data may represent a burrow, 

a burrow system, or an entire site that 

was surveyed which represents one or 

more burrows or burrow systems. 

Various techniques have been used to 

detect pygmy rabbit evidence on the 

landscape. Techniques may include 

driving and walking transects in 

perceived suitable habitat, winter aerial 

flights over potential habitat with 

subsequent selection of areas for further 

ground surveys (Rachlow and Witham 

2006, pp. 4-8), random searches in 

perceived suitable habitat, or spot 

lighting at night. Survey efforts have 

been made during all times of the year. 

It is advised that sites that indicate 

pygmy rabbit sign should be confirmed 

through sightings or photographic 

evidence; this may or may not have 

occurred. The Service has 

recommended using draft survey 

guidelines developed by Ulmschneider 

et al. (2004, entire) in conducting 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60522 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

pygmy rabbit surveys, but it has not 

always been used since its availability. 

Larrucea (2007, p. 3) tested pellet, 

sighting, burrow, and camera survey 

methods at 20 locations in 4 known, 

active pygmy rabbit populations in 

California and Nevada. She also 

assessed road transect surveys for 

detecting and determining relative 

abundance in an area (Larrucea 2007, p. 

3). Results indicated that pellets were 

found at all sites, but pellets determined 

to be fresh were found at only 70 

percent of the sites. Sighting individual 

rabbits provided positive results 30 

percent of the time. Burrows were 

located at 85 percent of the sites, but 

burrows determined to be active were 

found at only 55 percent of the sites. 

Cameras provided positive results 95 

percent of the time (Larrucea 2007, p. 6). 

Photographs were taken of pygmy 

rabbits at all types of active sites 

including those with only burrows 

determined to be inactive and with 

pellets determined to be old (Larrucea 

2007, p. 7). During the 10 transect 

counts, different rabbit and hare species 

were observed 569 times and 545 were 

identified to genus (Larrucea 2007, p. 7). 

Lepus was observed 491 times (90.1 

percent); Sylvilagus 44 times (8.1 

percent) and Brachylagus 10 times (1.8 

percent) (Larrucea 2007, p. 7). 

Photographs taken from the camera 

locations provided 409 photos of rabbit 

and hare species; the number of 

photographs of Lepus was 199 (48.7 

percent), Brachylagus 195 (47.7 

percent), and Sylvilagus 15 (3.7 percent) 

(Larrucea 2007, p. 7). 

Camera surveys are more effective 

than burrow, pellet, sightings, or road 

transect surveys for determining current 

pygmy rabbit activity at a site (Larrucea 

2007, p. 7). Burrows are a good indicator 

that pygmy rabbits may be present, but 

locating one does not mean pygmy 

rabbits are currently using the site 

(Larrucea 2007, p. 8). Lack of active 

burrows may not mean that there are no 

pygmy rabbits in the area. Burrows may 

be used seasonally, may be difficult to 

locate, or may be lacking in dispersal 

areas (Larrucea 2007, pp. 8-9). Old 

pellets do not confirm current use of a 

site and pellets may be misidentified 

due to young rabbits of other species 

cohabiting a site. Not finding fresh 

pellets does not mean pygmy rabbits are 

not currently using a site as 

environmental conditions can influence 

how rapidly pellets dry and change 

color (Larrucea 2007, p. 9). Sightings of 

individual pygmy rabbits do confirm 

current activity, but observers should be 

experienced as the young of cottontails 

(Sylvilagus spp.) and jackrabbits (Lepus 

spp.) can be confused with pygmy 

rabbits. Sightings of pygmy rabbits are 

difficult and do not occur often due to 

the dense vegetation inhabited, limited 

home ranges, and their elusive nature 

(Larrucea 2007, p. 10). Road transect 

surveys are inefficient for pygmy rabbits 

due to their reluctance to cross open 

areas and roads (Bradfield 1975, p. 3). 

Pygmy rabbits are more likely to run a 

short distance, sit tight, or disappear 

into a burrow than to run for a long 

distance making detection more difficult 

(Larrucea 2007, p. 10). 

We are also aware of difficulties in 

interpreting site activity during surveys. 

For example, in Montana, Lenard et al. 

(2005, p. 9) commented that 

comparisons of active to inactive 

burrows may be complicated, stating 

that burrows exhibiting current rabbit 

activity were easier to locate because 

tracks in the snow made them very 

apparent. The relative difference in 

abundance between currently active and 

recently active should not be interpreted 

to indicate any level of past versus 

current activity. Flinders et al. (2005, p. 

33), in Utah, commented that single 

burrow systems are harder to detect 

than multiple entrance burrow systems. 

The Bureau of Land Management (BLM) 

(2007a, p. 1) used the Ulmschneider et 

al. (2004, entire) method and noted that 

this type of inventory covered large 

expanses and typically found the larger 

pygmy rabbit populations and a small 

subset of the actual burrow systems on 

a particular site. However, when sites 

were re-inventoried intensively, BLM 

found numerous additional burrow 

systems. Lee et al. (2008, pp. 4-5), in 

Utah, commented that using criteria 

from Rachlow and Witham (2004b, pp. 

6-7) or Ulmschneider et al. (2004, 

entire) is somewhat inaccurate in 

predicting current pygmy rabbit burrow 

utilization. Lee et al. (2008, p. 5) used 

remote cameras to verify the presence or 

absence of pygmy rabbits in comparison 

to burrow classification. By using both 

burrow classifications methods along 

with remote cameras, refinement of 

burrow classifications and census 

techniques may be possible in the 

future. 

Bartels (undated) compared active 

and passive survey methods for 

detecting pygmy rabbit burrow 

occupancy at what she considered 

isolated and low density sites. She 

compared the use of an active survey 

method (peeper probe) and a passive 

survey method (surface classification of 

burrows using sign (burrows, pellets) to 

determine occupancy by pygmy rabbits 

(Bartels undated, pp. 3-4). A total of 233 

burrows were compared on 27 sites in 

Oregon and Idaho. Under the passive 

method, all 233 burrows were 

considered occupied (Bartels undated, 

p. 5). Under the active survey method, 

122 (52.4 percent) of the burrows were 

classified as occupied and as recently 

occupied, and 111 (47.6 percent) were 

classified as unoccupied (Bartels 

undated, p. 5). Bartels (undated, p. 7) 

recommended use of an active survey 

method in areas where pygmy rabbit 

numbers appear to be low and isolated 

sites are found. Viewing the internal 

attributes of burrows and establishing a 

standard for occupancy increases survey 

accuracy and could lead to greater 

accuracy when monitoring pygmy rabbit 

occupancy over time. 

We must also take into consideration 

complicating factors when interpreting 

current distribution and/or status as we 

do not have a complete understanding 

of pygmy rabbit habitat use. For 

example, it appears that some habitat 

use may be seasonal and pygmy rabbits 

may be somewhat migratory as some 

burrow systems appear occupied during 

certain times of the year and inactive 

during others, or from year to year 

(Flinders et al. 2005 p. 35; Bockting 

2007 p. 2; Larrucea 2007, pp. 96-97). 

Flinders et al. (2005 p. 35) reported that 

areas where pygmy rabbits were 

relatively abundant in Utah suddenly 

became sparse after the juveniles 

dispersed. Other areas then appeared to 

indicate an increase in the numbers of 

pygmy rabbits. In Utah, Flinders et al. 

(2005, p. 32) found active burrows were 

more common than the other activity 

classifications (i.e., recent, old, very 

old), and thus support statements that 

pygmy rabbits use more than one 

burrow system. He thought inactive 

burrows likely play an important role in 

providing escape cover. Cameras placed 

on burrows classified as old or very old 

documented use by pygmy rabbits. 

Larrucea (2007, p. 7) also photographed 

pygmy rabbits at sites where burrows 

were determined to be inactive. 

After reviewing the available 

information, we consider our approach 

in using information to determine the 

status of the pygmy rabbit to be 

conservative. We have used these data 

to compare historical (1999 and earlier) 

to current (2000 and later) distribution 

patterns. We have used the data to 

compare activity levels (active; inactive) 

of sites or burrows during these two 

time periods. Questions have been 

raised regarding surveyors’ abilities to 

accurately determine activity level due 

to possible detection differences, 

absence of long-term site monitoring, 

and our incomplete understanding of 

the pygmy rabbit’s life history 

requirements (e.g., possible seasonal use 

of some areas or periods of burrow nonuse). We are also aware that some 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60523 

survey techniques provide better data 

than others. Though these data are 

limited in their usefulness for our 

purposes due to their local, short-term 

nature, they are understood, by the 

Service to be the best available 

information. This data does provide 

baseline information that could be the 

foundation for future survey and 

monitoring efforts. 

Models 

To facilitate pygmy rabbit surveys in 

recent years, models of potential habitat 

have been developed for some States or 

study areas. Eliminating areas in these 

models that are unsuitable can be 

important as it can concentrate efforts 

and resources in areas that are more 

likely to support pygmy rabbits (Gabler 

et al. 2000, p. 763). Large areas that 

seem to be appropriate pygmy rabbit 

habitat may not be suitable based on the 

specific habitat characteristics needed 

for pygmy rabbits (Gabler et al. 2000, p. 

763). To aid pygmy rabbit research in 

Oregon, modeling efforts have been 

conducted by the following researchers: 

Bartels (2003, p. 35) for the BLM Burns 

District using GIS; Meisel (2006, p. 4) 

for the Hart Mountain National 

Antelope Refuge; and Hager and 

Lienkaemper (2007, pp. 1-2) for large 

blocks of State land. 

In Idaho, modeling efforts have been 

conducted by Rachlow and Svancara 

(2006, p. 828); Bartels (2003, pp. 35-38), 

and Gabler et al. (2000, pp. 762-763; 

2001 entirety). In Montana, Lenard et al. 

(2005, p. 1) reported on the 

development of four predictive models 

in Montana. In Wyoming, Purcell (2006, 

p. 28) used a probabilistic distribution 

map developed by Keinath and 

Thurston (2005, cited in Purcell 2006, p. 

28) using the combination of two 

models, DOMAIN (environmental 

similarity method) and CART 

(classification and regression tree 

analysis). Based on data collected 

during Purcell’s study, a new predictive 

distribution model was created (Purcell 

2006, p. 31). 

In Nevada, a predictive equation was 

produced based on habitat data 

collected and used as a model to 

characterize habitat where pygmy 

rabbits or sign occurred. The model 

explained the occurrence of pygmy 

rabbits or their sign on 56.7 percent of 

transects (Himes and Drohan 2007, p. 

376). Larrucea and Brussard (2008a, p. 

693) used GIS coverages. In Utah, Lee et 

al. (2008, p. 3) used vegetation data from 

the 2004 Southwestern Regional Gap 

Analysis Project. In general, these 

models are helpful in focusing survey 

efforts over a large area; however, 

researchers also recognize that due to 

scale and available data for particular 

attributes such as soils and vegetation, 

only on the ground surveying can 

positively indicate pygmy rabbit 

presence (Bartels 2003, pp. 92-94; 

Meisel 2006, pp. 26, 48; Lenard et al. 

2005, p. 1). 

We believe our large-scale, rangewide 

analysis, based on the Service’s 

databases, represents the best scientific 

and commercial information available 

on the distribution of pygmy rabbits. As 

mentioned above, many individual 

records were considered but not 

included in the Service’s databases for 

the following reasons: database records 

showing some level of uncertainty for 

the information being provided (e.g., 

other leporid species data included; 

uncertainty about whether pygmy rabbit 

was observed or other leporid species; 

using words such as ‘‘possible’’, 

‘‘potential’’, ‘‘maybe’’, ‘‘unsure’’); records 

that only provided location data or 

indicated pygmy rabbit sign with no 

additional information indicating what 

type of sign (e.g., burrow, pellet, track, 

sighting of animal as relates to 

reliability) had been observed; records 

related to telemetry locations (while 

informative in determining an 

individual’s distribution within its 

home range, this provides little 

information at the larger landscape scale 

used here; we did include the capture 

location of any individual pygmy rabbit 

trapped and fitted with a radio collar); 

records based solely on pellets or tracks 

due to concerns with species 

misidentification; those lacking key 

information (e.g., year which is needed 

for trend analysis); and duplicate 

records. 

Eliminating records with these types 

of concerns provides for a more accurate 

representation of pygmy rabbit rangewide distribution rather than including 

all records without considering some 

level of reliability of the data. While 

pygmy rabbits likely occur in additional 

unsurveyed areas and even in some 

areas that have been surveyed (pygmy 

rabbit sign can be easily overlooked), we 

have made our finding based on our 

review of these databases, which 

represent the best scientific and 

commercial information available. 

Distribution by State 

The following distribution and trend 

discussion is based on information 

obtained from published and 

unpublished literature and an 

interpretation of the survey location 

point data compiled in the Service’s 

databases. The following review does 

not discuss every document from the 

various information sources due to the 

volume, but a selection of literature that 

provides substantive historical 

information and survey information on 

a large scale. The literature is generally, 

but not entirely, associated with records 

included in the Service’s databases. 

This is because not all reports provided 

specific location points and not all 

location points are associated with a 

report, and as stated earlier, some 

records are not included in the Service’s 

databases. This analysis compares our 

understanding of the historical and 

current ranges of the pygmy rabbit 

discussed in this finding. 

Oregon 

The earliest pygmy rabbit records for 

the State of Oregon include: two 

specimens collected in Callow Valley, 

Harney County, Oregon (Nelson 1909, p. 

278); specimens collected near 

Ironsides, Malheur County, Oregon in 

1911-1912 (Anthony 1913, pp. 20-21); 

and 10 specimens collected near Baker, 

Baker County, Oregon (Dice 1926, p. 

27). 

Bailey (1936, pp. 110-111) indicated 

that pygmy rabbits in Oregon extended 

from the southern foothills of the Blue 

Mountain Plateau and eastern base of 

the Cascade Range over the southeastern 

quarter of the State. He reported that 

they were absent from areas of open 

country where sagebrush and rabbit 

brush were not abundant. As a result, 

there are numerous wide gaps in their 

range. 

Brodie and Maser (1966, pp. 11-12) 

reported the contents from owl pellets 

collected in 1966 at Lower Bridge, 

Deschutes County, Oregon. Prey animals 

consisted of pygmy rabbits. This 

location was reported as a new location 

for the pygmy rabbit as the nearest 

previously documented location was 

Redmond, Oregon (Hall and Kelson 

1959, cited in Brodie and Maser 1966, 

p. 12) about 10 miles (16.1 km) east of 

Lower Bridge. 

Olterman and Verts (1972, p. 25) 

listed 37 museum records for Oregon 

which occurred in general near the 

following areas: Baker, Baker County; 

Paulina, Crook County; Redmond, 

Deschutes County; Beakley, Beaties 

Butte, Burns, Rock Creek Ranch, Crane, 

Drewsey, Narrows, Sageview, Mud 

Lake, Steens Mountain, Voltage, and 

Waverly, Harney County; Fremont and 

Klamath Falls, Klamath County; Adel, 

Ft. Rock, Guano Creek, Guano Valley, 

Rabbit Creek, andSilver Lake, Lake 

County; and Cold Springs, Cow Creek 

Lake, Ironside, Mahogany Mountains, 

Malheur, McDermitt, Riverside, and 

Rome, Malheur County. At the time of 

their writing, Olterman and Verts (1972, 

p. 25) indicated recent observations by 

biologists demonstrated that pygmy 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60524 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

rabbits were occurring over the same 

area as in the past. Pygmy rabbits were 

observed near Hines, Wagontire, 

Lakeview, Hart Mountain National 

Antelope Refuge, Hampton, Ft. Rock, 

and Lower Bridges. 

Bradfield (1974, p. 39) also spent time 

at Ironside, in Malheur County, Oregon. 

He found evidence of previous pygmy 

rabbit use, but no fresh sign of use or 

rabbits, which supported his belief that 

they were in decline on a larger 

geographic scale. 

Weiss and Verts (1984, p. 563) 

attempted to search for pygmy rabbits in 

Oregon based on museum record 

information for sites listed in Olterman 

and Verts (1972, p. 25). Because of the 

generality of the location descriptions 

provided, they also reviewed aerial 

photography and soil maps to assist in 

narrowing searches in the areas 

described where pygmy rabbits had 

been collected previously (Weiss and 

Verts 1984, p. 564). Evidence of pygmy 

rabbits was found at 51 of 211 areas 

searched in 1982 (Weiss and Verts 1984, 

p. 566). In 1983, only 5 of the 15 sites 

that had been sampled for soil and 

vegetation information in 1982 showed 

recent pygmy rabbit activity (Weiss and 

Verts 1984, p. 566). Of 51 burrows 

found at 5 of the sites occupied in 1982, 

19 burrows were found open in 1983 

and 8 had fresh pellets (Weiss and Verts 

1984, p. 568). Only the locations of the 

15 occupied sites in Grant and Lake 

Counties where Weiss and Verts (1984, 

p. 566) recorded vegetation and soil data 

are provided in their document. 

Since 2000, additional survey efforts 

have been conducted. Bartels (2003, p. 

70) visited 54 previously known pygmy 

rabbit sites located on BLM lands in 

2000 and 2001 in Harney, Malheur, 

Lake, and Deschutes Counties, Oregon. 

Results from these visits showed 12 

sites were occupied, 8 were of 

undetermined occupancy, and 34 

showed no occupancy. Three additional 

sites were surveyed off of BLM lands. 

One site was occupied, one showed no 

evidence of pygmy rabbit use, and one 

was considered undetermined and 

warranted further investigation (Bartels 

(2003, p. 86). Some of these sites 

included those visited by Weiss and 

Verts (1984, p. 564) (Bartels 2003, p. 91). 

BLM conducted surveys on their 

Lakeview and Vale Districts in Harney 

and Lake Counties, Oregon in 2002 and 

2003 (BLM 2003a, p. 1). Forty-five sites 

were surveyed in fall of 2002 and winter 

2003 on the Lakeview District with 19 

sites indicating pygmy rabbit activity 

(10 active, 9 inactive). Twenty sites 

were surveyed in fall of 2002 and winter 

2003 on the Vale District with two sites 

indicating pygmy rabbit activity (1 

active, 1 inactive). The remaining sites 

surveyed (44) on the two districts in fall 

of 2002 and winter 2003 showed no 

evidence of pygmy rabbit use (BLM 

2003a, p. 1). During the summer of 

2003, 23 additional sites were surveyed 

and 19 showed pygmy rabbit activity 

(11 active, 8 inactive); 4 sites showed no 

evidence of pygmy rabbit use (BLM 

2003a, no page number provided). BLM 

continued to conduct surveys on their 

Burns and Lakeview Districts in Harney 

and Lake Counties, Oregon, 

respectively, in 2005 and 2006 (BLM 

2006a, pp. 3-4); active pygmy rabbit use 

was found at four of the seven sites 

surveyed. In 2006 and 2007, BLM 

surveyed 12 additional sites on the 

Lakeview District, and active pygmy 

rabbit use was found at 8 sites (BLM 

2007b, p. 1). Various numbers of burrow 

systems were found at the different sites 

(BLM 2003a, p. 3; BLM 2006a, pp. 3-4; 

BLM 2007b, pp. 3-6). 

Meisel (2006, p. 4), improved the 

known distribution of pygmy rabbits at 

Hart Mountain National Antelope 

Refuge, Lake County, during 2004 and 

2005. The sagebrush habitat on the 

refuge has been protected from 

development and other human 

disturbances for at least 70 years (Meisel 

2006, p. 9). Remote infrared 35-mm 

cameras were used to confirm 

occupancy by pygmy rabbits (Meisel 

2006, p. 12). Habitat characteristics were 

measured at 45 occupied burrows 

(Meisel 2006, p. 18). In 2005, refuge staff 

found approximately 99 occupied 

burrows near burrow locations that were 

found in 2004 by Meisel (R. 

Huddleston-Lorton, cited in Meisel 

2006, p. 27). Location information on 

these 99 burrows was not included in 

Meisel (2006). It is possible that a large 

population inhabits the northeast 

portion of the refuge (Meisel 2006, p. 

27). Meisel (2006, p. 27) recommends 

future research be conducted in areas of 

Wyoming big sagebrush to locate all 

burrows and document the population 

status on the refuge which is currently 

unknown. 

Hager and Lienkaemper (2007, p. 1) 

conducted surveys to determine the 

presence or absence of pygmy rabbits on 

State lands in Malheur, Harney, Lake, 

and Deschutes Counties. One hundred 

and fifty-seven sites were ground 

surveyed during 2004 and 2005 (Hager 

and Lienkaemper 2007, p. 3). Of the 157 

sites, 18 were determined to be active, 

14 inactive, and 125 showed no 

evidence of pygmy rabbit presence 

(Hager and Lienkaemper 2007, pp. 4-5). 

Most historical records (1999 and 

earlier) for Oregon occur in the 

following counties: Malheur, Harney, 

and Lake. A few historical records also 

occur in Baker, Grant, Crook, Deschutes, 

and Klamath Counties. There is also a 

1992 database sighting record for 

Jefferson County. Current information 

(2000 and later) indicates Malheur, 

Harney, and Lake as well as Klamath 

and Deschutes Counties continue to 

support pygmy rabbit activity. We are 

unaware of information indicating any 

recent survey efforts have been 

conducted to determine pygmy rabbit 

activity for Baker, Grant, or Jefferson 

Counties. Baker County indicated some 

activity in 1926. Grant County indicated 

inactivity during 1982 and 1983. 

Jefferson County had some activity in 

1992. The southeastern portion of Crook 

County was searched during 2005 by 

BLM, but pygmy rabbit evidence was 

not found. In general, pygmy rabbit 

activity continues to occur in 

southeastern Oregon in a similar 

distributional pattern as compared with 

historical information. 

Idaho 

Merriam (1891) was the first to 

describe the ‘‘Idaho pygmy rabbit (Lepus 

idahoensis)’’ based on a specimen 

collected on September 16, 1890, along 

the upper part of the Pahsimeroi River 

by Basil Dutcher (Merriam 1891, pp. 7, 

13, 75-78). Merriam (1891, p 75) 

indicated that the general distribution 

for the pygmy rabbit was the ‘‘Sage 

Plains’’ along the Snake River, and in 

Birch Creek and Lemhi Valleys, Little 

Lost River Valley, Pahsimeroi Valley 

and Big Lost River Valley, Idaho and 

into northern Nevada to the south, and 

to the west ‘‘probably’’ into eastern 

Oregon and Washington. 

Other early records include: six 

specimens collected from Big Lost River 

Valley, Birch Creek, Junction, Lost River 

Mountain, and Pahsimeroi Valley, Idaho 

(Nelson 1909, p. 278); and a report of 

two pygmy rabbits collected from 1 mi 

(1.6 km) west of Schutt’s Mine in 

November 1930 (Whitlow and Hall 

1933, p. 269). In May 1931, a female was 

collected near Trail Creek (Whitlow and 

Hall 1933, p. 270). These records 

extended the known range by 75 mi 

(120.7 km) to the southeast (Whitlow 

and Hall 1933, p. 270). Observations of 

pygmy rabbits in Idaho occurred near 

the head of the Pahsimeroi River, 

Idavada, Pahsimeroi Valley, Riddle, and 

Pocatello (Davis 1939, p. 364). Davis 

lists locations of 10 specimens 

examined: Owyhee County, near Riddle, 

2; Cassia County, Elba, 1; Butte County, 

Craters of the Moon National 

Monument, 1; Power County, near 

Michaud, 3; Bannock County, near 

Schutt’s Mine, 2; Trail Creek near 

Pocatello, 1. Additional records 

mentioned included Nelson’s (1909) 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60525 

records of Lemhi County, Junction; 

Custer County, Pahsimeroi Valley. 

Additional locations included Minidoka 

County, Minidoka (Seton 1929, cited in 

Davis 1939, p. 366); Cassia County, 

Burley (Grinnell et al. 1930, cited in 

Davis 1939, p. 366); Clark County, Birch 

Creek; Butte County, Big Lost River 

Valley; Lost River Mountains (Lyon 

1904, cited in Davis 1939, p. 366). Lyon 

(1904, cited in Davis 1939, p. 366) also 

includes a record from Ione Valley. 

Davis (1939, p. 366) was unable to find 

Ione Valley in Idaho and thought the 

specimen may have been from Nevada. 

Bradfield (1974, p. 39) speculated that 

the pygmy rabbit population was 

declining in his study area in Bingham 

County, Idaho. This was based on the 

number of abandoned burrows, number 

of skulls indicating death by predation 

or other means, and fewer observed 

rabbits. 

In her Idaho study area in portions of 

Idaho National Engineering and 

Environmental Laboratory (Laboratory) 

in Butte and Jefferson Counties, Gabler 

(1997, p. 42) found 101 burrow sites, of 

which 26 were active. Gabler (1997, p. 

94) also revisited Wilde’s (1978) three 

study areas on Laboratory lands, and 

found two collapsed burrows with no 

sign of occupancy; four active burrows 

which were abandoned 10 months later; 

and 34 abandoned burrows, 

respectively. 

Several surveys were conducted by 

Roberts between 1997 and 2004. In 1997 

and 1998, Roberts (2001, pp. 4-6) 

conducted surveys on BLM lands 

administered by the Salmon and Challis 

Field Offices (FO) in Lemhi and Custer 

Counties. The 3 areas occurred in the 

upper Lemhi River and upper Birch 

Creek Valleys; upper Pahsimeroi River 

and upper Little Lost River Valleys; and 

the upper Warm Springs Creek and 

upper Big Lost River Valleys. He found 

that pygmy rabbits were found widely 

scattered in all 3 of these areas (Roberts 

2001, pp. 10-11). In addition, Roberts 

(2001, p. 11) mentioned an occupied 

area in Railroad Canyon adjacent to 

Bannock Pass. This may be contiguous 

with habitat found in Horse Prairie 

Creek, Montana reported by Rauscher 

(1997, p. 13). Other areas of occupied 

rabbit habitat were found in Hawley 

Creek and in Bradshaw Basin (Roberts 

2001, p. 11). During 2002, Roberts 

(2003a, pp. 3, 5) conducted surveys in 

the Snake River Plains area in southern 

Idaho. Surveys were conducted on BLM 

lands within Idaho Falls, Pocatello, 

Shoshone, Owyhee, Jarbidge, and 

Burley FO areas, on U.S. Forest Service 

(USFS) lands within Targhee, Caribou, 

Cache, Sawtooth, Salmon, and Challis 

National Forests, and the Curlew 

National Grasslands. Roberts (2003a, p. 

6) found 9 currently active pygmy rabbit 

burrow systems. Four were found on the 

Owyhee FO, two on the Pocatello FO 

and one each in Idaho Falls and Jarbidge 

FO areas. One was found on the Curlew 

National Grasslands. Two systems were 

classified as recently active. One was 

found on the Owyhee FO area and the 

other on the Shoshone FO area. 

During the summer of 2003, Roberts 

(2003b, p. 3) searched areas in Big Lost 

River Valley, Little Lost River Valley, 

Birch Creek, and Medicine Lodge Creek 

for pygmy rabbits. He found three 

currently and recently active burrow 

sites in Big Lost River Valley; seven 

currently and recently active burrows in 

Little Lost River Valley; seven currently 

active burrow sites in Birch Creek where 

five pygmy rabbits were observed; and 

one currently active burrow site at 

Medicine Lodge Creek area. Another 

active burrow site was found in upper 

Medicine Lodge Creek (Targhee 

National Forest 3 miles from Bannock 

Pass). 

In 2004, Roberts (2004, p.2) continued 

to survey areas in Big Lost River Valley, 

Little Lost River Valley, Birch Creek, 

and Medicine Lodge Creek located in 

Butte and Clark Counties. He was 

unable to find pygmy rabbit evidence in 

the areas he searched in Big Lost River 

(Roberts 2004, pp. 3-4). He found 11 

currently active sites in Little Lost River 

area. In the Birch Creek area he found 

7 currently and recently used sites. He 

saw 6 pygmy rabbits at one of these 

areas. In this area, the pygmy rabbits 

were using cracks and crevices in and 

around large rocks and boulders as their 

burrows. In the Medicine Lodge Creek 

area he found 10 new burrow sites. He 

found 2 active burrows on the Targhee 

National Forest. Two additional active 

burrow sites were found on the U.S. 

Sheep Experiment Station. 

White and Bartels (2002, p. 1) 

surveyed for pygmy rabbits on 11 

grazing allotments in Twin Falls and 

Cassia Counties on BLM lands 

administered by the Burley FO. Results 

included 35 burrows found on 6 of the 

allotments (White and Bartels 2002, p. 

5). Twenty-four of the burrows were 

revisited with a peeper probe and six 

burrows located on two allotments were 

considered occupied by pygmy rabbits 

(White and Bartels 2002, p. 5). In 

addition, White and Bartels (2002, p. 7) 

attempted to visit 31 historical locations 

for pygmy rabbits in Cassia, Minidoka, 

Blaine, Power, and Oneida Counties, 

Idaho. Eighteen sites were too vague to 

relocate, eight were disturbed due to 

various factors, and five were 

potentially suitable habitat (White and 

Bartels 2002, pp. 7-8). No active pygmy 

rabbit burrows were found on any of the 

13 disturbed or potentially suitable sites 

visited. 

Red Willow Research Inc. conducted 

several surveys between 1999 and 2004. 

In 1999, Red Willow Research Inc. 

(2000, pp. 5-6) reported on sightings of 

pygmy rabbits at five locations in Cassia 

and Oneida Counties. Red Willow 

Research Inc. (2002, pp. 99-100) 

reported that all nine study areas within 

the BLM Shoshone FO area showed 

presence of pygmy rabbit use. Recent or 

current signs of occupancy were found 

at five individual sites along transects 

within three of the nine study areas in 

2001 and 2002. Red Willow Research 

Inc. (2004, p. 3) continued surveys in 

and adjacent to the nine study areas 

identified in the 2002 study. The 2004 

survey resulted in one sighting and one 

possible sighting of a pygmy rabbit, one 

inactive burrow system, and 

identification of additional areas for 

future survey efforts (Red Willow 

Research Inc. 2004, p. 4). 

North Wind, Inc. (2004, p. 2) surveyed 

for pygmy rabbits on BLM lands in eight 

areas located in the northern portions of 

the BLM Idaho Falls District. Five sites 

indicated recent or past pygmy rabbit 

use, including a pygmy rabbit sighting 

(North Wind, Inc. 2004, p. 13). 

Rachlow and Witham conducted 

several surveys between 2003 and 2006. 

Rachlow and Witham (2004a, p. 2) 

surveyed 12 locations in Camas, Blaine, 

and Gooding Counties, south central 

Idaho that had been identified as 

potential habitat in 2003. Two sites 

were confirmed to support pygmy rabbit 

populations. Witham and Rachlow 

(2004, p. 3) surveyed three potential 

sites at Craters of the Moon National 

Monument and Preserve in 2004 and 

found no evidence of pygmy rabbit 

presence. Rachlow and Witham (2005, 

p. 1) conducted a pilot study to test 

whether pygmy rabbit sign could be 

detected during aerial surveys in the 

Camas Prairie of south central Idaho. 

The study area included the two 

previously known locations found in 

2003 and confirmed in 2004 by Rachlow 

and Witham (2004a, pp. 2-3) (Rachlow 

and Witham 2005, p. 2). The aerial 

surveys identified 25 potential sites and 

21 were ground checked (Rachlow and 

Witham 2005, p. 7). Seven of the 21 

sites were confirmed to support pygmy 

rabbit populations (Rachlow and 

Witham 2005, p. 7). Rachlow and 

Witham (2006, p. 1) surveyed a portion 

of the Camas Prairie in south central 

Idaho by fixed-wing aircraft during 

February 2006. They identified 67 

potential sites from the air and 

evaluated 64 of them on the ground. 

Presence of pygmy rabbits was 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60526 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

confirmed at 32 sites. Sign at the 

remaining sites was attributed to 

cottontail rabbits or other species. These 

new locations expanded the known 

distribution of pygmy rabbits in the 

Shoshone FO area. 

BLM (2005a, p. 1) reported on surveys 

conducted between 2002 and 2005 on 

BLM lands within the Boise District 

(Owyhee FO). In 2002, four survey 

routes were walked and pygmy rabbit 

evidence was observed on each route 

(BLM 2005a, p. 2). Two sites were at or 

near previously known locations and 

two were new locations. One site was 

considered active. In 2003, 25 routes 

were walked and 12 locations found (7 

active or recent, 5 inactive) (BLM 2005a, 

p. 2). In 2004, 14 routes were walked 

and 2 new populations were found (1 

active or recent, 1 unrecorded activity 

level) (BLM 2005a, p. 2). In 2005, 242 

routes were walked with 16 new 

populations found (9 active or recent, 7 

inactive) (BLM 2005a, p. 2). 

Bartels (2005, p. 2) conducted pygmy 

rabbit surveys in the southern portion of 

BLM’s Jarbidge FO area during 2005. 

Sixteen pygmy rabbit burrows were 

identified with an additional 25 

documented as potential pygmy rabbit 

burrows. Burrows were generally 

located near Coonskin Butte, Pigtail 

Butte, Dorsey Table, Worley Draw, and 

Signal Butte. During the survey four 

pygmy rabbits were confirmed observed. 

These rabbits were observed at Worley 

Draw and Coonskin Butte. 

Waterbury (2005, p.3) conducted 

winter surveys in late 2004 and early 

2005 for pygmy rabbits in areas 

previously identified as potentially 

suitable habitat but where their 

presence or absence had not been 

conclusively determined on BLM 

(Salmon and Challis FO) and USFS 

(Leadore, North Fork, and Challis 

Ranger Districts) lands. Of the 38 

locations surveyed, pygmy rabbits were 

present at 12 of them (Waterbury 2005, 

p. 4). Waterbury (2006, p. 5) expanded 

search areas compared with previous 

efforts on BLM lands (Challis FO) 

located in Custer and Lemhi Counties. 

Surveys documented 269 positive 

detections of pygmy rabbits (burrows, 

tracks, pellets, sightings) over 20 areas 

(Waterbury 2006, pp. 9, 27-32). The 

areas of greatest concentrations occurred 

in Big Lost River Valley, Thousand 

Springs Valley, Pahsimeroi River Valley, 

Upper Spar Canyon, and Upper Road 

Creek (Waterbury 2006, p. 9). Forty-six 

pygmy rabbits were observed during the 

study (Waterbury 2006, p. 9). Of the 265 

positive detections associated with 

burrow systems, 91 percent were at 

active or recently active systems 

(Waterbury 2006, p. 9). These surveys 

expanded the known pygmy rabbit 

locations in the Challis FO and 

confirmed the persistence of historical 

populations in the Upper Pahsimeroi 

and Thousand Springs Valleys 

(Waterbury 2006, p. 11). 

Wackenhut (2008, pp. 4, 6, 7) 

conducted pygmy rabbit surveys across 

much of Bear Lake Plateau, Bear Lake 

County, Idaho between December 2006 

and March 2007. Information was 

collected on 568 active burrows in 19 

different locations across the plateau. 

Ten pygmy rabbits were sighted during 

the study. Fecal pellets were collected at 

19 individual burrows. DNA analysis for 

pygmy rabbit was positive for 13 of 

these samples; 5 samples were positive 

for mountain cottontail and 1 sample 

failed (Wackenhut 2008, p. 4). 

Most of the historical records (1999 

and earlier) for Idaho occur in the 

following counties: Owyhee, Cassia, 

Minidoka, Bannock, Bingham, Butte, 

Custer, and Lemhi. Additional records 

are from Canyon, Ada, Twin Falls, 

Lincoln, Power, Oneida, Blaine, Bear 

Lake, and Clark. Current information 

(2000 and later) indicates the following 

11 counties continue to support pygmy 

rabbit activity: Owyhee, Twin Falls, 

Cassia, Bear Lake, Lincoln, Blaine, 

Bingham, Butte, Custer, Lemhi, and 

Clark. Active areas were also found in 

the following counties without previous 

records: Washington, Gooding, Camas, 

Jefferson, and Fremont. Payette County 

indicated a recent inactive area. 

We are uncertain of the current 

pygmy rabbit activity in Canyon, Ada, 

and Bannock Counties because we are 

unaware of any survey efforts in 2000 or 

later occurring in these counties. 

Limited recent survey effort in 

Minidoka, Power, and Oneida Counties 

indicate inactivity at previously known 

sites. Records from Canyon and Ada 

Counties indicate activity in 1915 and 

1982, respectively. Power and Minidoka 

Counties indicate activity in the 1930’s 

and 1940’s, respectively. Both Bannock 

and Oneida Counties indicate activity in 

the 1990’s. However, recent survey 

efforts have expanded the known 

distribution in this State. Numerous 

previously unknown locations currently 

show signs of pygmy rabbit occupancy 

including locations in previously 

undocumented counties. 

Montana 

The pygmy rabbit was first 

documented in Montana in 1918 

(Hoffman et al. 1969, cited in Rauscher 

1997, p. 1). In 1963, a specimen was 

collected in Big Sheep Basin (Rauscher 

1997, p. 1). Between 1963 and 1997 no 

additional documentation regarding the 

pygmy rabbit in Montana occurred 

(Rauscher 1997, p. 1). 

Rauscher (1997, entirety) documented 

the results of pygmy rabbit surveys in 

Montana during 1996 and 1997. Pygmy 

rabbits occupied suitable habitat in most 

of Beaverhead County, the extreme 

southern end of Deer Lodge County, and 

the western edge of Madison County 

(Rauscher 1997, p. 5). Because of the 

discontinuous distribution of pygmy 

rabbits, every occupied site may not 

have been found, and as a result pygmy 

rabbits may occur outside of this range 

(Rauscher 1997, p. 5). Five of six 

historical sites were searched and four 

showed signs of occupation (Rauscher 

1997, p. 6). He mentioned some sites 

were found that no longer appeared to 

be occupied. These occurred west of 

Dillon, at the southern end of Dutchman 

Mountain, and at the northern edge of 

Frying Pan Basin (Rauscher 1997, p. 6). 

Rauscher concluded pygmy rabbits 

appeared to occupy much of the 

historical range (Rauscher 1997, p. 13). 

Janson (2002, p. 33) wrote that the 

historical range in Montana continues to 

support pygmy rabbits, with some 

exceptions. This was based on his 

limited observations in Beaverhead 

County, Montana in 2001. 

During 2004 and 2005, the Montana 

Natural Heritage Program conducted 

pygmy rabbit surveys for BLM (Dillon 

FO) to assess current distribution in the 

State (Lenard et al. 2005, p. 1). These 

surveys focused on Beaverhead (2004) 

and Madison (2005) Counties in areas of 

known use and areas where no activity 

had been previously documented 

(Lenard et al. 2005, p. 1). Due to snow, 

known locations in Horse Prairie, 

Medicine Lodge Creek (south of Ayers 

Canyon), Badger Gulch/Sagebrush 

Creek, and Upper Ermont Creek were 

inaccessible (Lenard et al. 2005, p. 1). 

New areas of pygmy rabbit activity were 

identified, expanding the current known 

distribution of the species (Lenard et al. 

2005, p. 1). In 2004, five previously 

known locations were surveyed and 

four of the five indicated current 

activity in Beaverhead County. The fifth 

showed recent activity (Lenard et al. 

2005, pp. 9-10). Seven new areas were 

surveyed and all showed current pygmy 

rabbit activity (Lenard et al. 2005, p. 10). 

In Madison County, five areas were 

surveyed in 2005. Although a few 

pygmy rabbit locations had been 

previously documented in one of these 

areas, the remaining areas were 

previously unknown to surveyors 

regarding pygmy rabbit occupancy. Of 

these five areas, three areas showed 

current activity; two areas showed 

recent activity (Lenard et al. 2005, p. 

12). Four new areas were surveyed and 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60527 

three areas were reported as showing no 

pygmy activity; one area could indicate 

a dispersal area as pellets were found 

but no burrows (Lenard et al. 2005, pp. 

12-13). 

In Montana, during the winter of 

2007, pygmy rabbit surveys were 

conducted in areas where no prior 

surveys had been conducted or where 

recent activity had not been 

documented in Beaverhead and Deer 

Lodge Counties (Hendricks et al. 2007, 

p. 3). Twenty-four sites were surveyed 

and four sites were found to have 

current pygmy rabbit activity 

(Hendricks et al. 2007, p. 9). Twelve 

sites had no evidence of pygmy rabbit 

activity, eight were considered 

unsuitable habitat for pygmy rabbits, 

and two were considered potential but 

were inaccessible due to snow 

(Hendricks et al. 2007, p. 9). Two active 

sites in Big Hole Valley were notable as 

they indicated current activity at sites 

that had not been resurveyed since they 

were active in 1997 (Hendricks et al. 

2007, p. 10). The two other active sites 

were previously undocumented pygmy 

rabbit sites (Hendricks et al. 2007, p. 

11). These new sites occurred in gaps 

between other locations suggesting 

additional locations may be found 

between those currently known 

(Hendricks et al. 2007, p. 13). The 

distribution and status of pygmy rabbits 

in Montana has become clearer since 

1997 (Hendricks et al. 2007, p. 15). 

However, Hendricks et al. (2007, p. 15) 

suggested additional surveys should 

occur in Centennial Valley, Jefferson 

River corridor north of Twin Bridges, 

Frying Pan Basin west of Dillon, and the 

Ruby River and Sweetwater Creek 

corridors. 

Most of the historical and recent 

records for Montana occur in the 

following two counties: Beaverhead and 

Madison. Current information (2000 and 

later) indicates these two counties, as 

well as Deer Lodge County, continue to 

support pygmy rabbit activity. There is 

a notable increase in the current 

distribution of the pygmy rabbit to the 

northeast in Madison County. 

Wyoming 

During the 1980’s and 1990’s a few 

reports documented pygmy rabbits in 

Wyoming. Campbell et al. (1982, p. 100) 

were the first to confirm the existence 

of pygmy rabbits in Wyoming. In 1981, 

6 specimens were collected, 17 

individuals were observed, and 2 skulls 

and many pellets were found at 2 sites 

in Uinta and Lincoln Counties in 

southwestern Wyoming (Campbell et al. 

1982, p. 100). These two new locations 

found in Wyoming extended the known 

range of the pygmy rabbits about 149 mi 

(240 km) to the southeast and 90 mi 

(145 km) to the northeast (Campbell et 

al. 1982, p. 100). Clark and Stromberg 

(1987, p. 75) reported three sites from 

Lincoln and Uinta Counties located in 

southwestern Wyoming. Garber and 

Beauchaine (1992, p. 3) compiled 

previously reported observations from 

Campbell et al. (1982, p. 100) and 

information from the Wyoming Game 

and Fish Department database. 

Although, this report does not indicate 

locations, which ones were revisited, or 

their status, several sites were revisited 

and new sites were found in 1990. 

Eleven new observations were recorded 

which increased records to 50 site 

confirmations (Garber and Beauchaine 

1992, p. 4). Documented observations 

expanded the known distribution in 

Wyoming by including two additional 

counties: Sublette and Sweetwater 

(Garber and Beauchaine 1992, p. 8). 

In 2004 and 2005, Purcell (2006, pp. 

1, 7-11, 30) conducted her study in 10 

areas in Lincoln, Sublette, Sweetwater, 

Fremont, and Carbon Counties. She 

found pygmy rabbits more widely 

distributed in southwestern and south 

central Wyoming than formerly thought 

due to previously unknown locations 

being found in Fremont and Carbon 

Counties. Purcell (2006, p. 32) suggested 

pygmy rabbits in Wyoming could occur 

as far east as Rawlins, as far north as 

Riverton, and as far south as Baggs. 

Western EcoSystems Technology, Inc. 

(2006, p. 1) conducted a pygmy rabbit 

survey in Lincoln and Uinta Counties, 

Wyoming. During the survey, 88 pygmy 

rabbit points indicating sign of pygmy 

rabbit presence were documented. 

Aster Canyon Consulting, Inc. 

conducted several surveys between 

2005 and 2007 in relation to proposed 

oil and gas facilities in Wyoming. These 

surveys provide pygmy rabbit sightings 

and signs in Lincoln, Sublette, and 

Sweetwater Counties. 

Grasslands Consulting, Inc. (2007, pp, 

1,2) conducted pygmy rabbit surveys in 

2007 in relation to three proposed oil 

and gas facilities in Sweetwater and 

Uinta Counties, Wyoming. These 

surveys provided pygmy rabbit sightings 

and signs in these counties. 

Most of the historical and recent 

records for Wyoming occur in the 

following four counties: Uinta, Lincoln, 

Sublette, and Sweetwater. Current 

information (2000 and later) indicates 

these counties continue to support 

pygmy rabbit activity. Recent survey 

efforts have expanded the known 

distribution in this State considerably as 

numerous previously unknown areas 

have been found in southern Sublette, 

southern Fremont, and eastern 

Sweetwater Counties. Areas in western 

Carbon County indicate a further range 

extension of the known distribution. 

California 

Early records indicate that pygmy 

rabbits were documented in eastern 

Modoc, Lassen, and Mono Counties. 

Henshaw (1920, p. 9) mentioned 

obtaining rabbit specimens in 

northeastern California at Goose Lake, 

Modoc County, in 1877 (at the time 

identified as Trowbridge’s hare (Lepus 

trowbridgei) but later determined to be 

Brachylagus idahoensis as described by 

Merriam). Grinnell et al. (1930, p. 553) 

collected 20 pygmy rabbit specimens 

during 1926 and 1928 in the vicinity of 

Ravendale, Lassen County. Orr (1940, p. 

195) observed pygmy rabbits on the 

south edge of the Madeline Plains, 

located east of Ravendale, in October 

1931. Severaid (1950, pp. 1-2) recorded 

observations and collection in 1948 of 

pygmy rabbits at Bodie, a famed gold 

mining ghost town, located in northern 

Mono County. The southern limit of 

their distribution in California was 

documented in 1955 in the vicinity of 

Crowley Lake in southern Mono County 

(Jones 1957, p. 274). 

During 2004, surveys were conducted 

on lands managed by BLM (Eagle Lake 

FO) in northern California (Sequin 2004, 

entirety). Twenty historical records are 

documented within the boundaries of 

the Eagle Lake FO and were located near 

Ravendale based on information 

provided by Grinnell et al. (1930) and 

Orr (1940). Pygmy rabbits were not 

found at any of the historical sites; no 

evidence of old or fresh pellets or 

burrows were seen (Sequin 2004, p. 6). 

Sequin (2004, p. 6) also surveyed 356 

potential sites for pygmy rabbit sign 

within the Eagle Lake FO boundary. No 

pygmy rabbit activity, either old or 

current, was found at any of these 

potential sites (Sequin 2004, p. 6). As all 

potential pygmy rabbit habitat was not 

surveyed, it is possible that pygmy 

rabbits may still be found within the 

Eagle Lake FO boundary (Sequin 2004, 

p. 8). 

Larrucea and Brussard (2008a, pp. 

692, 694-695), surveyed locations in 

Nevada and California between 2003 

and 2006 which includes information 

reported in Sequin (2004). In California, 

active sites were found in Mono County, 

but not in Modoc or Lassen Counties 

(Larrucea and Brussard 2008a, p. 694). 

This area is on the edge of the pygmy 

rabbit’s western range (Larrucea and 

Brussard 2008a, p. 694). It is possible 

that pygmy rabbits have been extirpated 

from Modoc and Lassen Counties. A 

range contraction would be more 

expected in a peripheral area, such as 

northern California, if it were to occur 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60528 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

(Larrucea and Brussard 2008a, p. 696). 

The Mono County populations may be 

isolated from other known populations 

because they appear to be separated by 

a distance of approximately 100 mi (162 

km) from the nearest known 

populations in Nevada (Larrucea and 

Brussard 2008a, p.694). These pygmy 

rabbit populations may have become 

isolated from more eastern populations 

at the end of the Pleistocene (Grayson 

2006, pp. 2969-2970). 

There are only a few historical (1999 

and earlier) records for California which 

included Modoc, Lassen, and Mono 

Counties. Current information (2000 and 

later) indicates that while pygmy rabbit 

activity continues to occur in Mono 

County, pygmy rabbits may have been 

extirpated from both Modoc and Lassen 

Counties in northeastern California. Due 

to limited survey efforts in northern 

California overall, uncertainty remains 

whether this contraction has actually 

occurred. Therefore, Figure 1 does not 

depict this possible range contraction. 

Nevada 

The earliest pygmy rabbit records for 

Nevada include a collection of 12 

pygmy rabbits from Paradise, Humboldt 

County, Nevada in 1908 and 1909 

(Nelson 1909, p. 278). Nelson also 

indicated he examined 23 additional 

specimens from Halleck, Ione Valley, 

Monitor Valley, Reese River, and 

Skelton, Nevada. 

Hall (1946, p. 618) indicates he 

examined 56 pygmy rabbit specimens 

and sight records from several locations 

throughout the State. The years of these 

collections and sightings are not 

included but were recorded for the 

following eight counties: Washoe, 

Humboldt, Pershing, Churchill, Lander, 

Nye, Elko, and White Pine. The range 

map for Nevada also included Eureka 

County and a portion of Lincoln County 

(Hall 1946, p. 615). 

During 1993 and 1994, surveys were 

conducted on Sheldon National Wildlife 

Refuge lands located in Washoe and 

Humboldt Counties. Twenty-four 

surveys were completed; 17 locations 

were found to be occupied by pygmy 

rabbits (Service 1995, p. 1). In 2002, 

surveys were conducted on the refuge 

and locations reported in 1993 and 1994 

were also revisited (Service 2004, p. 1). 

In total, 41 sites were surveyed for 

pygmy rabbits and 18 had pygmy rabbit 

sign of which 15 sites were confirmed 

with photography (Service 2004, p.2). 

Ten of the sites from the mid 1990’s had 

pygmy rabbit sign in 2003. Fifteen new 

sites were surveyed in 2003; eight of 

these showed pygmy rabbits and/or 

their sign (Service 2004, p. 2). 

Marriott (2005, p. 4) reported 

conducting surveys for pygmy rabbits in 

all or portions of 23 units on the Ruby 

Lakes National Wildlife Refuge and an 

area immediately adjacent to refuge 

lands, located in Elko and White Pine 

Counties in 2004 and 2005. Evidence of 

pygmy rabbits was found in seven units. 

The populations reported by Ports and 

Ports (1989, p. 127) were found in the 

sand dune area adjacent to two of the 

refuge units (Marriott (2005, p. 4). It was 

confirmed that at least 27 burrows were 

active (Marriott (2005, p. 4). Three 

pygmy rabbits were observed (Marriott 

2005, p. 5). The surveyors were 

confident that they had not found all the 

burrow systems within the refuge 

boundaries (Marriott 2005, p. 7). They 

also suspected that more pygmy rabbits 

occur in the sand dune area as they 

were unable to survey the entire area 

(Marriott 2005, p. 8). In 2006, Wienke 

(2006) reported conducting pygmy 

rabbit surveys in two areas of the Ruby 

Lakes National Wildlife Refuge and 

adjacent BLM lands. The sand dune area 

survey found 44 pygmy rabbit burrow 

systems of which 20 appeared to be 

active (Wienke 2006, p. 2). Three pygmy 

rabbits were observed (Wienke 2006, p. 

2). In the Unit II-D area, 162 burrow 

systems were found; 53 were active 

(Wienke 2006, p. 2). Ten pygmy rabbits 

were observed (Wienke 2006, p. 2). 

Etzelmiller (2003, p. 1) conducted 33 

survey transects in northwestern Nye 

County, Nevada in 2003 and 10 showed 

evidence of pygmy rabbit sign. Pygmy 

rabbits appear to be concentrated in 

Indian, Eastern Ione, and Upper Reese 

River Valleys (Etzelmiller 2003, p. 3). 

In 2003 Himes and Drohan (2007) 

surveyed for pygmy rabbits in White 

Pine, Lincoln, and Nye Counties in 

eastern and central Nevada. Pygmy 

rabbit sign (individuals, burrow, pellets) 

was found along 261 of 642 transects 

(40.7 percent) walked (pygmy rabbits 

and/or fresh burrows and pellets on 89 

transects (13.9 percent); fresh pellets 

only on 33 transects (5.1 percent); old 

burrows and pellets on 113 transects 

(17.6 percent); old pellets only on 26 

transects (4.0 percent)). No sign was 

observed on 381 transects (59.3 percent) 

(Himes and Drohan 2007, p. 376). The 

southern limit of the previously known 

record in Nevada was extended by about 

7.5 mi (12 km) south (Himes and 

Drohan 2007, p. 376). All transects 

where pygmy rabbits and/or sign of 

pygmy rabbit presence were observed in 

the study area were considered new 

locations. Due to the extreme 

remoteness and fairly inaccessible 

terrain in the survey area, additional 

localities are almost certain to remain 

undocumented (Himes and Drohan 

(2007, p. 380). 

During surveys conducted between 

2003 and 2006, a total of 1,474 locations 

were surveyed in Nevada and California 

(Larrucea and Brussard 2008a, pp. 692, 

694-695). Pygmy rabbits were 

documented at 258 sites (Larrucea and 

Brussard 2008a, p. 694). The current 

distribution of active sites in Nevada is 

similar to the historical distribution 

(Larrucea and Brussard 2008a, p. 694). 

Active sites were found throughout the 

historical range (Larrucea and Brussard 

2008a, pp. 694-695). Positive 

(confirmed) locations for pygmy rabbits 

in Larrucea (2007) should be considered 

as minimum occurrence because it 

occurred on a large, state-wide basis 

(Larrucea 2007, p. 28). Information from 

Larrucea (2006) was incorporated into 

the Larrucea (2007) study. Associated 

with the previous study (Larrucea 2007), 

Larrucea and Brussard (2008b, p. 1638) 

revisited 105 sites based on 118 

historical records from Nevada (109) 

and California (9) dated between 1877 

and 1946 for current pygmy rabbit 

presence. Pygmy rabbits were found to 

be present at 36 percent of the historical 

sites (Larrucea and Brussard 2008b, p. 

1638). When a radius (buffer) around a 

positive location was increased to 3.1 

mi (5 km) around a historical site, 

positive locations increased to 48 

percent, and when a radius of positive 

location was increased to 6.2 mi (10 km) 

around a site, positive locations 

increased to 60 percent (Larrucea 2007, 

p. 56). As indicated in Larrucea and 

Brussard (2008a) many additional sites 

were found throughout the historical 

range. 

The Southern Nevada Water 

Authority (2007, p. 5) conducted pygmy 

rabbit surveys in 2005 and 2006 in Dry 

Lake, Cave, Lake, and Hamlin Valleys in 

Lincoln County and Spring, Snake, and 

Steptoe Valleys in White Pine County, 

Nevada. Fifty-six locations were 

surveyed and 15 had pygmy rabbit sign 

(SNWA 2007, p. 5). There was one 

confirmed and one potential pygmy 

rabbit sightings observed (SNWA 2007, 

p. 5). Pygmy rabbit sign occurred in 

Cave, Dry Lake, and Lake Valleys, 

Lincoln County and Spring Valley, 

White Pine County (SNWA 2007, pp. 5- 

10). 

Most of the historical records (1999 

and earlier) for Nevada document 

occurrences in the following counties: 

Elko, Eureka, Lander, White Pine, and 

Nye Counties. There are fewer records 

from Washoe, Humboldt, Pershing, and 

Churchill Counties. Current information 

(2000 and later) indicates all of these 

counties, with the exception of Pershing 

County, continue to support pygmy 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60529 

rabbit activity, and across a broader area 

within those counties than historically 

noted. Pershing County is an exception 

because we are unaware of any recent 

survey efforts being conducted in the 

County, and therefore do not know if 

pygmy rabbits continue to exist there. In 

addition, pygmy rabbit activity has been 

found in Lincoln County. The recent 

survey efforts have located populations 

over a greater area within the State and 

the expansion of the known range has 

occurred most notably in Washoe, 

Lincoln, and Nye Counties. 

Utah 

Early reports of pygmy rabbits 

occurring in Utah include the first 

reporting in 1932 after having been 

detected in 1931 (Stanford 1932, cited 

in Oliver 2004, p. 14). Janson (1940, p. 

6) collected pygmy rabbits from Blue 

Creek Hills 10 miles (16.1 km) west of 

Tremonton and in Iron County about 5 

miles (8 km) west of Cedar City. He 

observed them in the valley bottom west 

of Parowan. Anecdotal reports to Janson 

indicated that pygmy rabbits occurred at 

the foot of Lake Mountains west of Utah 

Lake. Janson (1940, p. 6) thought it was 

‘‘probable’’ the pygmy rabbit occurred in 

‘‘a more or less broken strip through the 

Upper Sonoran sagebrush areas of 

western Utah from the northern 

boundary of the State nearly to the IronWashington County line southwest of 

Cedar City.’’ In 1946, Janson (1946, p. 

32) wrote that the pygmy rabbit 

‘‘appears’’ to extend through Utah west 

of the Wasatch Mountains from the 

Idaho border to the northern border of 

Washington County. He reported 

specimens had been collected near 

Clarkston, Cache County; Blue Spring 

Hills and Grouse Creek, Boxelder 

County; and near Modena, Lund, 

Kanarraville, and Cedar City, Iron 

County. Pygmy rabbits or their sign had 

been observed near Snowville, Lucin, 

and Promontory, Boxelder County; and 

Parowan, Iron County. He mentioned a 

reliable report of their presence west of 

Utah Lake, Utah County, and a 

questionable report west of Trout Creek 

(county unknown). Schantz (1947, p. 

187) noted, based on three specimens 

collected by Janson in 1938, a 270 mile 

(434.4 km) southern expansion of 

known pygmy rabbit distribution in 

Utah from Promontory, Boxelder 

County, to Cedar City, Iron County. 

Janson (1946, p. 84) reported that in 

the winter of 1946, pygmy rabbits 

appeared to be more scarce than in 1941 

based on two study areas in Utah (near 

Cedar City, Iron County; near 

Tremonton, Box Elder County). Areas 

where he considered pygmy rabbits 

common in Utah in 1941 were found to 

have no pygmy rabbits occupying them 

in 1946. 

Durrant (1952, p. 88) reported that the 

pygmy rabbit range in Utah included 

Boxelder, Cache and Iron Counties and 

‘‘probably’’ occurred between areas 

along the eastern margin of Pleistocene 

Lake Bonneville. He also listed 

additional records provided by Janson 

(1946, pp. 32-33) and included Juab 

County (Durrant 1952, p. 89). 

Holt (1975, p. 131) indicated 

considerable information was obtained 

that altered the distributional range of 

the species. Populations from Sevier 

River tributaries and surrounding areas 

indicated that the pygmy rabbit was not 

restricted to the Upper Sonoran life 

zone (Holt 1975, p. 132). Holt (1975, pp. 

136-138) indicated additional 

specimens have been examined from 

Boxelder, Tooele, Millard, Sevier, 

Beaver, Piute, Garfield, and Washington 

Counties. These are in addition to 

Janson’s (1946, pp. 32-33) records or 

sightings from Boxelder, Cache, Utah, 

Juab, and Iron Counties. 

Pritchett et al. (1987, p. 231) reported 

pygmy rabbit records outside of the 

published range in the Bonneville 

Basin. One record is near Panguitch, 

Garfield County (Stephenson 1966, cited 

in Pritchett et al. 1987, p. 231). They 

mention Holt’s (1975, p. 137) record of 

a population south of Fish Lake on 

Parker Mountain and a collection and 

sighting of pygmy rabbits south of Fish 

Lake Ranger Station and west of Loa, 

Wayne County. In addition, Pritchett et 

al. (1987, p. 231) reported collecting six 

live individuals and two skulls from the 

Parker Mountain region of the Awapa 

Plateau, Wayne County. The Awapa 

Plateau is part of the Fremont River 

watershed and is outside of the 

Pleistocene Lake Bonneville drainage. 

During 1986, Pritchett et al. (1987, p. 

233) looked for pygmy rabbits or their 

sign and were able to find evidence 

from Burrville, about 0.5 mi (0.8 km) 

northwest of Parker Mountains, south 

through Grass Valley to north of Otter 

Creek Reservoir. They were unable to 

find Holt’s (1975, p. 137) population 

west of Otter Creek Reservoir Pritchett 

et al. (1987, p. 233). They wrote that the 

valley between Kingston and Otter 

Creek is narrow and disturbed. They 

found no evidence of pygmy rabbits 

from Sigurd to Burrville or through 

Emery Valley. 

Based on the two previous study areas 

in Utah between 1938 and 1946, and 

limited observations in Utah (near 

Clarkston, Cache County; near 

Snowville and Grouse Creek, Box Elder 

County) in 2001, Janson (2002, p. 32) 

wrote that recent information indicated 

pygmy rabbit populations had declined 

in some areas where they were 

previously more abundant, mostly as a 

result of human actions. He states that 

residential and commercial 

development, farming, and range 

improvements for grazing, especially 

near Cedar City, had impacted the 

sagebrush habitat. He found no recent 

sign of occupancy near Cedar City, 

Utah. 

Oliver (2004 pp. 16-18) provides a 

review of pygmy rabbit in Utah and lists 

location records for the pygmy rabbit 

between 1946 and 2003 which includes 

the following 14 counties: Washington, 

Boxelder, Garfield, Piute, Iron, Sevier, 

Cache, Beaver, Rich, Wayne, Toole, 

Millard, Juab, and Utah. 

In 2005, Welch (2005, pp. 15-17, 36) 

conducted walking surveys of 48 big 

sagebrush stands or sites in Utah (41 

sites in Box Elder, Rich, Tooele, Davis, 

Utah, Wasatch, Duchesne, Uintah, Juab, 

Carbon, Sevier, Beaver, Piute, Wayne, 

Iron, and Washington Counties), Idaho 

(4 sites in Cassia and Oneida Counties), 

and Nevada (3 sites in Elko and White 

Pine Counties) in 2003 and 2004. 

Twelve of these sites were known to 

have supported pygmy rabbits in the 

past, 26 possibly supported pygmy 

rabbits in the past, and 10 sites had no 

record of past use (Welch 2005, p 2). Of 

the 12 sites known to have supported 

pygmy rabbits in the past, 4 were found 

to support pygmy rabbits or current sign 

(Cassia County, Idaho; Piute and Rich 

Counties, Utah; Elko County, Nevada); 

of the 26 possible historical sites, 1 was 

found to support current pygmy rabbit 

activity during his study (Iron County, 

Utah) (Welch 2005, pp. 9, 14-17, 36). In 

addition, he surveyed 13 other sites 

previously listed by Janson (2002, pp. 

10-11) (Welch 2005, p 2). Of these 13 

sites, none showed signs of current use; 

only 5 had some remaining suitable 

habitat (Welch 2005, p 10). 

Flinders et al. (2005, p. 7) surveyed 

habitat in Grass Valley in Piute, Sevier, 

and Wayne Counties located in south 

central Utah. Pygmy rabbit surveys were 

conducted in areas slated for sagebrush 

treatment but where pygmy rabbit 

surveys had not been previously 

conducted as well as revisiting areas 

where pretreatment pygmy rabbit 

surveys had been completed by BLM 

employees (Flinders et al. 2005, p. 13). 

According to Flinders et al. (2005, p. 

13), BLM surveys identified 118 active 

burrow systems and 85 inactive ones. 

Flinders et al. (2005, p. 13) found 14 

locations with active burrow systems 

and all others found in treatment areas 

were determined to be inactive. 

During 2005 and 2006, Larsen et al. 

(2006) surveyed for pygmy rabbits in 

Deep Creek watershed, Tooele County. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60530 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

This watershed is located on the UtahNevada border and the closest known 

extant pygmy rabbit population in 

Nevada occurs about 52 miles (84 km) 

to the northwest (Larsen et al. 2006, p. 

4). The Nevada population had been 

surveyed within the past 5 years (Larsen 

et al. 2006, p. 4). Four historical (1905- 

2002) sites showed no evidence of 

present occupation by pygmy rabbits 

(Larsen et al. 2006, p. 5). In addition, 

three active pygmy rabbit locations 

(confirmed with photography) and three 

inactive ones were found within the 

watershed (Larsen et al. 2006, pp. 5-6). 

Pygmy rabbits were not photographed at 

the inactive sites and fresh pellets were 

lacking; however, given the recent 

activity and the potential for 

reoccupation, the authors believed these 

inactive sites are important to the 

species in the watershed (Larsen et al. 

2006, p. 15). Interestingly, based on the 

map provided by Larsen et al. (2006, p. 

16), the three inactive sites and the three 

active sites are located north and south 

of the historical sites, respectively. 

Flinders (2007, pp. 2-3) indicates 

discovery of fairly extensive 

populations in Hamlin Valley located 

on the Utah-Nevada border in Iron and 

Beaver Counties. Numerous burrows 

systems classified as current or recently 

current have been found in the area. 

This area may provide a corridor 

between Utah and Nevada pygmy rabbit 

populations. Pygmy rabbit use was 

found on both sides of the border. 

In summary, most historical records 

(1999 and earlier) for Utah occurred in 

the following six counties: Boxelder, 

Iron, Washington, Garfield, Piute, and 

Wayne Counties. Fewer records 

occurred in Beaver, Millard, Juab, 

Tooele, Sevier, Utah, Rich, and Cache 

Counties. Current information (2000 and 

later) indicates Boxelder, Tooele, 

Beaver, Iron, Washington, Garfield, 

Piute, Wayne, Sevier, and Rich Counties 

continue to support pygmy rabbit 

activity. Current pygmy rabbit activity is 

uncertain in Cache, Utah, and Juab 

because we are unaware of any recent 

survey efforts occurring in these 

counties. A new area in Millard County 

was searched in 2003 and activity was 

not observed. The recent survey efforts 

have located active population in 

Sanpete County and in additional areas 

previously unknown within the other 

counties where surveys have occurred. 

Abundance 

We are unaware of any historical or 

current population estimates being 

made for the pygmy rabbit by individual 

States or for the range considered in this 

finding. Any figures related to numbers 

of pygmy rabbits provided in the 

literature have been reported as 

individuals collected (Dice 1926 p. 27 

(10 in Oregon); Grinnell et al. 1930, pp. 

553-554 (20 in California), p. 555 (35 in 

Nevada); Bailey 1936, p. 111 (8 in 

Oregon); Severaid 1950, p. 2 (4 in 

California); Borell and Ellis 1934, pp. 

41-42 (7 in Nevada)), or individuals 

observed (Grinnell et al. 1930, p. 553 (1 

in California); Bailey 1936, p. 111 (40 in 

Oregon); Jones 1957, p. 274 (1 in 

California); Bartels 2003, p. 88 (5 in 

Oregon); Rachlow and Witham 2004a, p. 

3 (20 in Idaho); Flinders et al. 2005 p. 

45 (250 in Utah)), or individuals 

photographed (Flinders et al. 2005 p. 45 

(241 in Utah)) or individuals live 

trapped (Rauscher 1997, p. 9 (58 in 

Montana); Rachlow and Witham 2004a, 

p. 3 (25 in Idaho); Crawford 2008, p. 22 

(337 in Nevada and Oregon)), or 

mortalities reported related to study 

efforts (Rauscher 1997, p. 9 (11 in 

Montana)) in various parts of its range 

by researchers. 

Other authors used qualifying 

statements to indicate abundance 

(Anthony 1913, p. 22, in Oregon wrote, 

‘‘On account of the thick growth and the 

animal’s habit of circling about under 

cover an accurate count of the 

inhabitants of such a locality was 

difficult to obtain.’’ Anthony (1913, p. 

21) also stated that the species was ‘‘not 

uncommon’’ around Ironside, Malheur 

County, Oregon; Bailey (1936, p. 111) 

stated that Oregon pygmy rabbits are 

locally abundant only where conditions 

are favorable. Janson (1940, p. 41) wrote 

that pygmy rabbits in Utah occur in 

scattered communities which are 

limited by characteristics favorable to 

the pygmy rabbit. In these areas where 

characteristics favorable to the pygmy 

rabbit are found, the pygmy rabbit may 

be quite abundant. 

Under the species description 

provided above, several researchers 

have reported a variety of density 

estimates for pygmy rabbits on 

individual sites. However, the number 

of active burrows may not be directly 

related to the number of individuals in 

a given area because some individual 

pygmy rabbits appear to maintain 

multiple burrows, while some 

individual burrows are used by multiple 

individuals (Janson 1940, pp. 21, 29; 

Janson 1946, p. 44; Gahr 1993, pp. 66, 

68; Heady 1998, p. 25). It is not 

appropriate to extrapolate any of these 

reported densities beyond the local 

scale due to the patchy distribution of 

suitable habitat and the variable amount 

of habitat actually occupied (Keinath 

and McGee 2004, p. 20). Efforts to 

model the amount and distribution of 

suitable habitat have met with minimal 

success and are useful mainly for 

focusing future survey efforts (Keinath 

and McGee 2004, p. 20). 

More recently, attempts have been 

made to estimate pygmy rabbit 

abundance by different methods. 

Rachlow and Witham (2004b, pp. 2-13) 

in Idaho evaluated several census 

techniques for pygmy rabbits (thermal 

imagery, burrow surveys, live trapping, 

line transect surveys, fecal pellet 

counts). They found several techniques 

were infeasible due to cost or the 

likelihood of providing imprecise 

estimates. Surveys of burrow systems 

provide an obtainable index of activity, 

but more work is needed to associate 

this index with population density 

estimates (Rachlow and Witham 2004b, 

p. 13). Price (2008, p. 2) in Idaho is 

attempting to develop a standardized 

method to monitor abundance of pygmy 

rabbits. Price is attempting to calibrate 

an index of abundance based on burrow 

systems by correlating the index with 

estimates of population density. 

Sanchez (2007, p. 108) states that tools 

used for estimating relative abundance 

of pygmy rabbits rely on locating and 

assessing burrows and fecal pellets. 

Sanchez evaluated the temporal changes 

in fecal pellets and burrow systems to 

assess their potential usefulness as 

indicators of relative abundance of 

pygmy rabbits (Sanchez et al. 2009, p. 

427). The persistence and detectability 

of pellets and burrows over time may be 

influenced by factors such as weather, 

soil microorganisms, invertebrates, 

vertebrates, vegetative growth, or the 

soil’s susceptibility to slumping or 

compaction (Sanchez et al. 2009, p. 

427). Sanchez et al. (2009) determined 

that next to actual sightings of pygmy 

rabbits, burrow systems and pellets are 

the most reliable evidence of pygmy 

rabbit presence in an area; together they 

may provide an indirect index of 

population trend but depend on the 

objectives of the investigator as multiple 

factors can affect changes in pellets and 

burrows over time (Sanchez et al. 2009, 

p. 433). Therefore, reliably estimating 

the abundance of pygmy rabbits on a 

statewide or range wide basis is not 

currently possible. 

Trend 

Population trends are normally 

defined in terms of distribution or 

abundance. In the case of the pygmy 

rabbit, the available scientific 

information does not allow for an 

analysis of abundance over time. 

Abundance trends for the pygmy rabbit 

in each State and throughout its range 

are unknown and how impacts to the 

sagebrush habitat from various events or 

actions have affected pygmy rabbit 

abundance remain unclear. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60531 

Distribution information obtained 

from early literature and records 

represent a collection of sightings 

documented by different individuals 

over time. These early records were not 

collected in a systematic, 

comprehensive manner with the goal of 

determining the pygmy rabbit’s 

distribution. However, they do reflect 

the species historical distribution 

known or suggested at that time, which 

was modified as previously unknown 

locations were found. Our 

understanding of the distributional 

trend throughout the species’ range has 

improved only recently. 

Surveys have concentrated on 

documenting populations within a 

particular State by revisiting historical 

sites and looking for previously 

unknown sites. It is important to 

understand that considering only 

contemporary surveys of historical sites 

is likely to result in an apparent loss of 

a species from any number of locations 

regardless of whether the species has 

suffered a decline in numbers or not 

(Shaffer et al. 1998, cited in Larrucea 

and Brussard 2008b, p. 1639). 

Populations naturally fluctuate locally 

so some historical sites are expected to 

disappear due to chance alone (Hanski 

1991, cited in Larrucea and Brussard 

2008b, p. 1639). In addition, it is often 

difficult to determine whether pygmy 

rabbit activity continues in a particular 

area because many historical site 

descriptions are vague. 

With the possible exception of 

California and Nevada, recent survey 

efforts have not been comprehensive in 

individual States. Due to funding 

limitations, various individuals from 

various agencies have selected different 

areas in each State to survey. As a 

result, different methodologies were 

developed for these surveys. Some 

individual sites or locations have been 

destroyed while some populations may 

have relocated to other areas across the 

landscape because of various factors. 

Appropriately, surveys have also 

expanded into new areas and have 

found previously undocumented pygmy 

rabbit populations. These efforts have 

improved our understanding of the 

species’ current distribution across its 

range. Because of the emphasis in 

determining where pygmy rabbits occur 

on the landscape, monitoring of known 

sites over time has essentially not 

occurred for pygmy rabbit populations. 

Historical records provide no 

information on the amount of area 

where pygmy rabbits were collected or 

observed. Rarely do recent survey efforts 

report the amount of acreage attributed 

to occupied or unoccupied pygmy rabbit 

burrow systems. Therefore, we are 

unable to compare changes in the 

amount of acres used historically or 

currently by pygmy rabbits. 

Because of this lack of long-term 

distributional data, we have compared 

active and inactive (occupied versus 

unoccupied) records in the Service’s 

databases from 1877 to 1999 to active 

and inactive records from 2000 to 2008. 

Based on a comparison of these two 

groups of records, the distribution of 

pygmy rabbits is quite similar to our 

understanding of the historical range in 

all States except California as discussed 

in more detail above. Not only do 

pygmy rabbits continue to occupy the 

general areas previously known, new 

areas of current activity have been 

documented due to increased survey 

efforts in recent years. We are 

encouraged by recent survey efforts and 

that researchers continue to find 

populations where they occurred 

historically. These survey efforts have 

also lead to the discovery of active areas 

in previously unknown or 

undocumented locations, and assist in 

improving our understanding of the 

distribution of the pygmy rabbit across 

its range. 

In some States (Montana, Nevada, and 

most notably Wyoming) these increased 

survey efforts have led to an extension 

of the current distribution of pygmy 

rabbits within these States. We are not 

suggesting that these populations have 

expanded in these States, only that 

increased survey efforts have located 

previously unknown or undocumented 

populations of this species. It appears 

that recent survey efforts have not 

occurred in the peripheral counties in 

Oregon so we are unsure of current 

pygmy rabbit activity in these areas. 

Idaho also shows some uncertainties 

because of some inactive areas and we 

are unaware of previous areas being 

revisited; however, active areas have 

also been found in previously unknown 

areas and counties. Utah shows some 

uncertainties because we are unaware of 

previous areas being revisited. Active 

areas have been found in previously 

unknown areas and counties in Utah. It 

is possible that California has 

experienced a relatively small range 

contraction in the northeast in Modoc 

and Lassen Counties. Because we 

eliminated undesirable records from our 

analysis, as explained above, we believe 

we have presented a conservative look 

at our current understanding of the 

distribution of the pygmy rabbit across 

its range. The pygmy rabbit not only 

occurs generally throughout its 

historical range, it also occurs in 

previously unknown or undocumented 

areas, thus increasing our understanding 

of the species’ current distribution. 

Habitat 

Sagebrush is the most widespread 

vegetation in the western United States’ 

intermountain lowlands (West and 

Young 2000, p. 259). A number of 

species and subspecies of sagebrush are 

recognized (Connelly et al. 2004, p. 5- 

2) and each has unique habitat 

requirements and responses to 

disturbances (West and Young 2000, pp. 

259-261). Sagebrush species and 

subspecies occur in areas dictated by 

local soil type, soil moisture, and 

climatic conditions (West 1983, pp. 333, 

355-357; West and Young 2000, pp. 259- 

261). The degree of dominance by 

sagebrush varies with local site 

conditions and disturbance history. 

Plant associations, typically defined by 

perennial grasses, further describe 

distinctive sagebrush communities 

(Miller and Eddleman 2001, p. 14; 

Connelly et al. 2004, p. 5-3) and are 

influenced by soil type, elevation, 

topography, and precipitation. 

Sagebrush species are long-lived with 

some surviving to 100 years (West and 

Young 2000, p. 259). Allelopathic 

chemicals are produced that reduce 

seed germination, seedling growth and 

root respiration of competing plant 

species and inhibit the activity of soil 

microbes and nitrogen fixation. 

Sagebrush species are resistant to 

environmental extremes, with the 

exception of fire and on occasion 

defoliating insects (West 1983, p. 341). 

Most species of sagebrush are killed by 

fire (Miller and Eddleman 2001, p. 17; 

West and Young 2000, p. 259). The 

natural re-colonization of sagebrush in 

burned areas depends on the presence 

of adjacent live plants for a seed source 

or on a seed bank, if present (Miller and 

Eddleman 2001, p. 17). 

Sagebrush species are typically 

divided into two groups, tall sagebrush 

(also known as ‘‘big’’) and low 

sagebrush, based on their affinities for 

different soil types (West and Young 

2000, p. 259). Within tall sagebrush, 

there are three subspecies, Artemesia 

tridentata ssp. wyomingensis (Wyoming 

big sagebrush), A. t. ssp. tridentata 

(basin big sagebrush), and A. t. ssp. 

vaseyana (mountain big sagebrush) 

which are the most widely distributed 

(Knick et al. 2003, p. 614). There are two 

primary species in the low sagebrush 

group: A. arbuscula (low sagebrush) and 

A. nova (black sagebrush) (Knick et al. 

2003, p. 614). Big sagebrush occurs in 

coarse-textured and/or well drained 

sediments, while low sagebrush 

typically occurs where erosion has 

exposed clay or calcified soil horizons 

(West and Young 2000, p. 261). Big 

sagebrush will die if saturated long 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60532 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

enough to create anaerobic conditions 

for 2 to 3 days (West and Young 2000, 

p. 259). Some low sagebrush species are 

more tolerant of occasionally 

supersaturated soils, and many low 

sagebrush sites are partially flooded 

during spring snowmelt. Sagebrush 

species do not tolerate high salinity 

soils (West and Young 2000, p. 270). 

Sagebrush and sagebrush ecosystem 

response to natural and human 

influenced disturbances varies based on 

the sagebrush species and its 

understory, as well as abiotic factors 

such as soil type and precipitation. 

Mountain big sagebrush, for example, 

generally can recover more quickly and 

robustly than Wyoming big sagebrush 

following a disturbance (Miller and 

Eddleman 2001, p. 22) likely due to its 

occurrence on moist, well drained soils 

as compared to the very dry soils typical 

of Wyoming big sagebrush communities. 

Soil associations have resulted in 

disproportionate levels of habitat 

conversion across different sagebrush 

communities. Basin big sagebrush 

occurs at lower elevations, in soils that 

retain moisture two to four weeks longer 

than in well drained, but dry and higher 

elevation soils typically occupied by 

Wyoming big sagebrush. As a result, 

sagebrush communities dominated by 

basin big sagebrush have been converted 

to agriculture more extensively than 

communities found on poorer soils 

(Winward 2004, cited in 70 FR 2254). 

The effects of disturbance on sagebrush 

species are not constant across their 

range. 

Within the sagebrush ecosystem, there 

are two primary features of pygmy 

rabbit habitat: relatively taller and 

denser big sagebrush and deep soils 

(Ulmschneider et al. 2004, p. 2). Pygmy 

rabbit burrows are usually found in the 

taller and denser sagebrush within an 

area. The height of the sagebrush can 

vary greatly, from approximately 1.5 to 

7 ft (0.46 to 2.1 m). Sagebrush density 

can also vary, but it is common that the 

sagebrush canopy cover at burrows is 

greater than 30 percent (within a 20-ft 

(6.1 m) radius of burrow) (Ulmschneider 

et al. 2004, pp. 2, 23). Occupied habitat 

includes various subspecies of 

sagebrush, including Wyoming, 

mountain, and basin. Other shrub 

species may also be present, including 

Purshia tridentata (bitterbrush), rabbit 

brush, Sarcobatus vermiculatus 

(greasewood), Symphoricarpos spp. 

(snowberry), and Juniperus spp. 

(juniper). In Oregon and Nevada, some 

areas occupied by pygmy rabbits 

include rabbit brush as dominant or codominant with sagebrush and burrows 

have been found under large, dense 

rabbit brush and greasewood 

(Ulmschneider et al. 2004, p. 2). 

Pygmy rabbits can also occupy habitat 

that does not appear ideal. These areas 

include sagebrush that is short in height 

and ‘‘bad’’ soil. In east central Idaho, 

pygmy rabbits occupy ‘‘mima mounds’’ 

(mounds of soil several feet (ft) high and 

approximately 20 to 30 ft (6.1 to 9.1 m) 

in diameter) with taller and denser 

sagebrush dotted in a landscape of 

shorter and thinner sagebrush. In 

Montana, the average sagebrush height 

in occupied sites can be about 15 in 

(38.1 cm). In Montana, pygmy rabbits 

have been found in areas where the 

sagebrush is not very dense and is about 

30 in (76.2 cm) high, especially in 

mountain bowls and where sagebrush 

has been manipulated. In Utah, pygmy 

rabbits have been found to occupy 12 to 

120-inch (30.5 to 304.8 cm) tall 

sagebrush. Regardless of the absolute 

height of the vegetation, pygmy rabbits 

will almost always burrow in the tallest 

and densest sagebrush on the landscape 

(Ulmschneider et al. 2004, pp. 2-3). 

Generally, pygmy rabbits burrow in 

loamy soils deeper than 20 in (50.8 cm). 

Soil composition needs to be soft 

enough for digging, yet be able to 

support a burrow system. In southwest 

Idaho, pygmy rabbits occur in areas 

with soils classified as stony sandy 

loam, and sandy loam over sandy clay 

and clay loam. In east central Idaho, 

soils are gravelly outwash plains with 

lime-coated rocks. On the lava plains of 

southeast Idaho, rabbits will often 

burrow between or under lava boulders. 

In Nevada, soils are light-colored and 

friable (easily crumbled) (Ulmschneider 

et al. 2004, p. 3). 

Occupied pygmy rabbit habitats in 

Oregon are very similar to those in 

Idaho (below). Most habitat occurs 

where big sagebrush inclusions are 

mixed with low sagebrush, rabbit brush, 

or shorter stature big sagebrush. 

Mounding similar to ‘‘mima mounding’’ 

occurs in most of these sites. Sagebrush 

on the mounds is usually 1 to 3 ft (0.30 

to 0.91 m) taller than those in the 

surrounding area. Another common 

type of occupied habitat in Oregon is 

small draw bottoms where deeper soils 

have collected. Most of these sites are 

vegetated with basin big sagebrush in 

the drainage bottom, surrounded by 

Wyoming big sagebrush, low sagebrush, 

or mountain big sagebrush in the 

surrounding uplands. Some areas 

utilized by pygmy rabbits are dominated 

by rabbit brush. Some soil mounding 

can occur in these areas, but can be 

subtle. Burrows in these areas seem to 

be restricted to the very bottom of the 

drainages or the lower inside slopes of 

the drainage (Ulmschneider et al. 2004, 

p. 4). 

In Oregon, Weiss and Verts (1984, p. 

567) found mean shrub cover in areas 

occupied by pygmy rabbits was about 29 

percent and mean shrub height was 

about 33.1 in (84 cm). Mean shrub cover 

best distinguished occupied sites from 

adjacent sites (29 versus 18 percent), 

followed by mean soil depth (51 versus 

31 cm), and mean shrub height (84 

versus 53 cm). Percent basal area of 

perennial grasses, density of annual 

grasses, density of forbs, and 

components of soil texture were found 

to contribute little to the difference 

between occupied areas and adjacent 

sites. Meisel (2006, p. 21) found average 

sagebrush height 2.1 ft (0.65 m) and 

percent sand content in the soil (50.2 

percent) as the two variables that 

determined occupied burrows. 

Unoccupied burrows had an average 

sagebrush height of 1.0 ft (0.32 m) and 

45.5 percent sand in the soil sample. 

In Idaho, pygmy rabbits are found in 

mima mound areas. In the Salmon, 

Idaho area, pygmy rabbits are found on 

alluvial plains dotted with mounds 

about 20 to 30 ft (6.1 to 9.1 m) in 

diameter, 1 to 2 ft (0.3 to 0.61 m) tall, 

several hundred ft or yd apart, where 

the sagebrush is taller than in the 

surrounding inter mound spaces. In 

southwest Idaho, a similar habitat is 

occupied by pygmy rabbits where big 

sagebrush islands are intermingled with 

low sagebrush. In the Owyhees of 

southwest Idaho, pygmy rabbits are 

found in swales of taller sagebrush. Soil 

mounding is present, but it does not 

form distinctive mima mounds. In the 

Bruneau Plateau, pygmy rabbits are 

found in the bottoms and lower slopes 

of small drainages where the sagebrush 

is denser and taller, indicating deeper 

soils (Ulmschneider et al. (2004, p.3). In 

the Owyhees of southwestern Idaho, 

Burak (2006, pp. 63-64) found occupied 

pygmy rabbit areas had significantly 

greater total shrub, sagebrush (A. t. ssp. 

vaseyana), forbs, and litter cover, and 

significantly less bare soil and rock than 

in unoccupied areas. Total shrub, 

sagebrush (A. t. ssp. vaseyana) and 

snowberry cover was greater in 

occupied pygmy rabbit habitat. Height 

of total shrubs and sagebrush was also 

significantly higher in occupied areas. 

Total shrub cover values ranged from 41 

to 67 percent. Sagebrush cover values 

ranged from 12 to 60 percent. These 

differences in total shrub cover and 

sagebrush cover suggest that total shrub 

cover does not need to be comprised of 

sagebrush primarily. It is unknown what 

minimum amount of sagebrush cover is 

needed for pygmy rabbit survival. Burak 

(2006, p. 65) found in his study areas 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60533 

average total shrub and sagebrush height 

to be 160 in (63 cm) and 167.6 in (66 

cm), respectively. 

Pygmy rabbits in Montana are found 

in habitats similar to those in Idaho and 

Oregon- large intermountain valley 

bottoms, alluvial fans, mountain valleys 

and bowls, drainage bottoms, plateaus, 

rolling sagebrush plains and isolated 

patches of sagebrush in grasslands. 

Preferred habitat in Montana appears to 

be gently sloping or nearly level 

floodplains where adequate sagebrush 

and appropriate soils exist. However, 

many occupied sites have marginal 

sagebrush cover and shallower soils. If 

pygmy rabbits are found in areas 

containing mima-like mounds, they 

generally occur throughout the 

continuous sagebrush coverage at 

varying densities and into sagebrush 

drainages (Ulmschneider et al. 2004, p. 

4). 

In Wyoming, pygmy rabbits occur in 

swales of taller, denser sagebrush in a 

setting of hillsides with thinly 

distributed, shorter sagebrush. The 

general areas used by pygmy rabbits 

have evenly distributed, taller, and more 

structurally diverse sagebrush with a 

dense canopy. Three subspecies of big 

sagebrush can be present, basin, 

Wyoming, and mountain (Ulmschneider 

et al. 2004, p. 5). In Wyoming, Purcell 

(2006, p. 62) found that the proportion 

of bare ground and shrub cover may 

influence habitat features used by 

pygmy rabbits. Of the 10 study areas, 6 

had significantly less bare ground at use 

sites than at non-use sites. Six of the 10 

study areas had significantly greater 

shrub cover at use sites compared with 

non-use sites. Although sagebrush was 

the dominant shrub in all study areas, 

other shrubs contributed to the shrub 

cover. In relation to soils, Purcell (2006, 

pp. 64-65) found 8 of the 10 study areas 

showed a higher fine fraction of soil in 

both the surface and subsurface levels at 

use sites. The amount of coarse material 

in the soil may not inhibit digging if the 

soil is soft. Both surface and subsurface 

samples indicated that softer soils 

occurred at the use sites compared with 

the non-use sites. There did not appear 

to be a relationship between soil texture 

and areas used by pygmy rabbits 

(Purcell 2006, p. 65). 

Western EcoSystems Technology, Inc. 

(2008, pp. 18, 20, 22-23) found the 

dominant habitat types within 6.6 ft (2 

m) of pygmy rabbit burrows along three 

pipeline routes in 2007 were tall 

sagebrush (42 percent), low sagebrush 

(48 percent), and desert scrub (10 

percent). The average percent of 

different shrub types located within 16 

ft (5 m) of pygmy rabbit burrows along 

two of the pipeline routes in 2006 

indicated tall sagebrush at 56.6 percent, 

low sagebrush at 34.7 percent, and 

greasewood at 7.7 percent. Average 

percentages of shrub cover within 6.6 ft 

(2 m) of burrows along the three routes 

in 2007 show 58 percent of burrows had 

between 26 and 50 percent shrub cover. 

Twenty-eight percent had a shrub cover 

of between 11 and 25 percent. Along 

two of the routes in 2006, pygmy rabbit 

burrows were found in 33.3 percent 

loam, 30.2 percent clay, and 20.3 

percent sand. 

In California, pygmy rabbits occupy 

areas near Mono Lake in islands of big 

sagebrush and loamy soils, similar to 

areas in Nevada, but with sandier soils. 

Burrows tend to be in sandy loam soils, 

which are often surrounded by very 

sandy soils. Near Bodie, an abandoned 

mining town approximately 10 mi (16.1 

km) north of Mono Lake, the habitat 

includes shorter, more uniform 

sagebrush, often less than 3 ft (0.9 m) 

tall, with less clumping of the 

sagebrush. Pygmy rabbit habitat in 

northeastern California is very similar to 

habitat in adjacent Nevada 

(Ulmschneider et al. 2004, p. 5). 

In Nevada, pygmy rabbits are found in 

broad valley floors, drainage bottoms, 

alluvial fans, and other areas with 

friable soils. Burrows can be located in 

mounds (either natural or human 

caused) when they are available in these 

types of soils. Pygmy rabbit burrows are 

easiest to find in light colored, friable 

soils. These soils are usually found in 

valley bottoms and can be associated 

with rabbit brush or sagebrush 

vegetation. The understory of grasses 

and forbs can vary from almost none to 

dense (Ulmschneider et al. 2004, p. 4). 

In California and Nevada, Larrucea and 

Brussard (2008a, pp. 695-697) found 

mean sagebrush cover at occupied sites 

was 44.7 percent. Mean sagebrush 

height at occupied sites was 38.8 in 

(98.4 cm), but it was not found to be a 

significant factor. Pygmy rabbits were 

more likely to occupy sites within 

clusters of sagebrush located higher 

than the surrounding sagebrush or in 

sagebrush islands. These islands 

occurred in a range of surrounding 

sagebrush heights of 4.7 to 46.1 in (12 

to 117 cm). These islands also had 

greater sagebrush cover. Occupied sites 

were located on loamy soils with a 

mean sand and clay content of 39.1 

percent and 20.4 percent, respectively. 

Pygmy rabbits occupied sites with little 

or no understory. 

In Utah, site characteristics inhabited 

by pygmy rabbits vary considerably, 

because they occupy three different 

ecoregions: Central Basin and Range, 

Wyoming Basin, and the Wasatch and 

Uintah Mountain. These ecoregions vary 

in latitude, elevation, precipitation, and 

geologic history. Pygmy rabbits are 

found in the western half of the state in 

alluvial deposits and in favorable micro 

sites on ‘‘bench tops’’. Habitat in 

northern Utah is characterized by 

Wyoming, mountain, and basin big 

sagebrush, and bitterbrush and 

snowberry present at the higher 

elevations. Pygmy rabbit habitat in 

southern areas is often limited to the 

bottom of gentle drainages supporting 

Wyoming sagebrush with black 

sagebrush, Atriplex confertifolia 

(shadscale), and Kochia americana (gray 

molly) community of minimal height 

(11.0 in, 28 cm) (Ulmschneider et al. 

2004, p. 5). 

Evaluation of Information Pertaining to 

the Five Threat Factors 

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

and implementing regulations (50 CFR 

part 424) set forth procedures for adding 

species to, removing species from, or 

reclassifying species on the Federal 

Lists of Endangered and Threatened 

Wildlife and Plants. Under section 

4(a)(1) of the Act, a species may 

determine to be endangered or 

threatened on the basis of any of the 

following five factors: 

(A) The present or threatened 

destruction, modification, or 

curtailment of its habitat or range; 

(B) Overutilization for commercial, 

recreational, scientific, or educational 

purposes; 

(C) Disease or predation; 

(D) The inadequacy of existing 

regulatory mechanisms; or 

(E) Other natural or manmade factors 

affecting its continued existence. 

In making this 12–month finding, 

information pertaining to the pygmy 

rabbit in relation to the five factors 

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

discussed below. In making our 12– 

month finding on the petition, we 

considered and evaluated the best 

scientific and commercial information 

available. 

In considering what factors might 

constitute threats to a species, we must 

look beyond the exposure of the species 

to a factor to evaluate whether the 

species may respond to the factor in a 

way that causes actual impacts to the 

species. If there is exposure to a factor 

and the species responds negatively, the 

factor may be a threat and we attempt 

to determine how significant a threat it 

is. The threat is significant if it drives, 

or contributes to, the risk of extinction 

of the species such that the species 

warrants listing as endangered or 

threatened as those terms are defined in 

the Act. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60534 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Factor A: The Present or Threatened 

Destruction, Modification, or 

Curtailment of the Species’ Habitat or 

Range 

The following potential factors that 

may affect the habitat or range of the 

pygmy rabbit are discussed in this 

section, including: (1) Habitat 

conversion, (2) agriculture, (3) 

sagebrush treatment, (4) livestock 

grazing, (5) nonnative invasive plants, 

(6) fire, (7) pinyon-juniper woodlands 

encroachment, (8) urban and rural 

development, (9) mining (10) energy 

exploration and development, (11) 

habitat fragmentation, (12) habitat 

manipulation conducted to benefit 

greater sage-grouse (Centrocercus 

urophasianus urophasianus), and (13) 

conservation strategies and actions. 

Habitat Conversion 

Sagebrush once covered 

approximately 270 million ac (109 

million ha) in western North America 

within 13 States (Washington, Oregon, 

Idaho, Montana, Wyoming, North and 

South Dakota, Colorado, New Mexico, 

Arizona, Utah, Nevada and California 

(American Lands Alliance 2001, p. 3). 

Today, because of various land uses, 

about 150 million ac (61 million ha) of 

sagebrush habitat remain (American 

Lands Alliance 2001, p. 3). Pygmy 

rabbits occur within a portion of this 

area, but they are not known to occur in 

Arizona, Colorado, North or South 

Dakota, or New Mexico. The amount of 

sagebrush acres suitable for supporting 

pygmy rabbits is a subset of the 

remaining acres in the states they are 

known to occur, based on the species’ 

specific habitat needs within the range 

of the sagebrush ecosystem. Therefore, 

the amount of suitable sagebrush habitat 

for pygmy rabbits has always been less 

than the total amount of sagebrush 

acreage distributed across western North 

America. 

A number of activities have been 

identified as potentially impacting 

pygmy rabbit habitat and individuals or 

populations across the species’ range. 

These activities most commonly include 

land management practices which result 

in the direct loss of sagebrush habitat 

(e.g., conversion of sagebrush habitat to 

agricultural purposes, sagebrush 

treatment to increase forage for 

livestock); livestock grazing; invasive 

nonnative plant species; fire; urban and 

rural development; mining; energy 

exploration and development; 

fragmentation of sagebrush habitat, and 

sagebrush modification for other species 

such as greater sage-grouse (Roberts 

2001, p. 17; Red Willow Research Inc. 

2002, pp. 58-59, 64-65; Bartels 2003, pp. 

101-104; Keinath and McGee 2004, pp. 

14, 23-25; Hayden Wing Associates, Inc. 

2008b, p. 1; Larrucea 2006, p. 7; 

Larrucea and Brussard 2008b, p. 1636). 

As discussed in the background 

section, the pygmy rabbit is a sagebrush 

obligate, but it occurs within a subset of 

the sagebrush ecosystem within its 

range. Pygmy rabbits are found where 

sagebrush cover is sufficiently tall and 

dense and where soils are sufficiently 

deep and loose to allow burrow 

construction (Bailey 1936, p. 111; Green 

and Flinders 1980a, p. 2; Campbell et al. 

1982, p. 100; Weiss and Verts 1984, p. 

563; WDFW 1995, p. 15). Thus, pygmy 

rabbits are not distributed uniformly 

across the full range of the sagebrush 

shrub-steppe ecosystem. In large areas 

of the sagebrush habitat, pygmy rabbits 

are not known to occur, and in those 

areas where it does occur it is patchily 

distributed. For each of the following 

potential threats listed in Factor A, the 

available information provides general 

characteristics of sagebrush habitat 

degradation or provides examples of 

impacts in site-specific areas resulting 

in possible impacts to pygmy rabbits. 

Agriculture 

Large-scale conversions of western 

rangelands to agricultural lands began 

under the Homestead Acts of the 1800’s 

(Todd and Elmore 1997, cited in Braun 

1998, p. 4). More than 70 percent of the 

sagebrush shrub-steppe habitat has been 

converted to agricultural crops in some 

States (Braun 1998, p. 2). Hironaka et al. 

(1983, cited in 70 FR 2255) estimated 

that 99 percent of basin big sagebrush 

habitat in the Snake River Plain has 

been converted to cropland. Across the 

Interior Columbia Basin of southern 

Idaho, northern Utah, northern Nevada, 

eastern Oregon and Washington, about 

15 million ac (6 million ha) of shrubsteppe habitat has been converted to 

agricultural cropland (Altman and 

Homes 2000, p. 10). Development of 

irrigation projects to support 

agricultural production also resulted in 

sagebrush habitat loss (Braun 1998, p. 

4). Reservoirs have been constructed to 

facilitate these irrigation projects, 

impacting native shrub-steppe habitat 

adjacent to rivers, as well as supporting 

the conversion of more upland shrubsteppe habitat to agriculture. As 

irrigation techniques have improved, 

additional land has been irrigated, and 

more big sagebrush (A. tridentata) 

cleared. Shrub-steppe habitat continues 

to be converted to dry land and irrigated 

cropland but at a much lower rate 

(Braun 1998, p. 4). 

Review of current sagebrush steppe 

habitat and agricultural lands within 

Great Basin sagebrush among states 

within the range of the pygmy rabbit 

show that less than 10 percent is 

impacted by agriculture for Oregon, 

Montana, Wyoming, California, Nevada 

and Utah. Only Idaho has a greater 

percentage of agricultural lands within 

Great Basin sagebrush at about 18 

percent (75 FR 13925). 

The loss or modification of sagebrush 

habitat due to agricultural conversion 

and impacts to pygmy rabbits across its 

range could include injury or death at 

the time of vegetation clearing, 

reduction in forage and shelter, 

temporary or permanent home range 

abandonment, increased habitat 

fragmentation, increased dispersal 

barriers, increased predation, and 

population declines. As a sagebrushdependent species, complete loss of 

sagebrush over a large area could have 

long-term impacts to pygmy rabbits. 

According to Roberts (1998, p. 11), of 

the 583,600 ac (236,180 ha) he 

inventoried in Lemhi and Custer 

Counties, Idaho for pygmy rabbit 

occupancy, 122,300 ac (49,494 ha) had 

been permanently removed due to 

agriculture conversion. However, the 

acreage or percentage of land that had 

been occupied by pygmy rabbits is 

unknown. White and Bartels (2002, pp. 

7-8) believe that the pygmy rabbit 

historically was impacted by sagebrush 

removal for agricultural purposes in 

Idaho as 3 of 13 historic sites they 

visited were disturbed by agriculture, 

and pygmy rabbit activity was not 

observed at these sites. 

In Utah, Pritchett et al. (1987, p. 233) 

reported that a portion of the Sevier 

River Valley between Kingston and 

Otter Creek, containing one of the last 

large patches of sagebrush, had been 

plowed. They speculated this may 

previously have been a dispersal route 

for pygmy rabbits from Iron County to 

Wayne County, Utah. Janson (2002, pp. 

31-32) reported in 2001 that he found 

wheat acreage had expanded in the Blue 

Springs Hills of Box Elder County and 

that the sagebrush was almost gone. He 

also stated that the foothills area near 

Clarkston, Cache County had 

experienced increased farming activity 

which had eliminated sagebrush. Larsen 

et al. (2006, p. 5) visited four historical 

pygmy rabbit sites in Tooele County, 

Utah which were unoccupied. Some of 

them (number not indicated) showed 

evidence of conversion to farmland. 

In Utah, Idaho, and Nevada, Welch 

(2005, p. 10) visited historical pygmy 

rabbit sites in 2003 and 2004. He 

mentioned 7 of 13 were impacted or 

likely impacted by agricultural 

conversion to farmland including wheat 

and alfalfa fields. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60535 

In Montana, Rauscher (1997, p. 16) 

thought conversion of sagebrush to 

agriculture was minimal in southwest 

Montana because of the large expanses 

of public land. He documented that the 

suspected location for one historical 

pygmy rabbit record had been converted 

to irrigated farmland (Rauscher 1997, p. 

14). 

In California, Williams (1986, p. 51) 

indicated that loss of sagebrush habitat 

in California to agriculture was less of 

a concern than loss of habitat to 

overgrazing. Larrucea and Brussard 

(2008b, p. 1638) revisited 105 of 118 

historical pygmy rabbit sites from 

Nevada (109) and California (9) dated 

between 1877 and 1946 to document 

current pygmy rabbit presence. They 

determined the presence or absence of 

current land use (agricultural 

conversion, livestock grazing, fire, 

urbanization and presence of pinyonjuniper) at each site. This was to 

determine what type of impacts were 

presently occurring, and they do not 

imply that these land use practices are 

what led to the loss of pygmy rabbits at 

any of the extirpated sites (Larrucea and 

Brussard 2008b, p. 1638). Larrucea and 

Brussard (2008b, p. 1639) found 

agricultural fields at 6 of the 105 

historical sites. Most historical sites 

occurred in the foothills and not on 

valley floors where vegetation was more 

meadow-like. This may have changed 

after 1880 as excessive grazing reduced 

grasses, increased erosion, and lowered 

water tables and fire suppression 

allowed sagebrush to increase on valley 

floors (Miller and Rose 1999, cited in 

Larrucea and Brussard 2008b, p. 1640), 

creating pygmy rabbit habitat at these 

lower elevations. 

Summary of Agricultural Impacts 

Information indicating loss of 

sagebrush due to agricultural conversion 

in specific portions of the pygmy 

rabbit’s range has been documented. 

However, because of the pygmy rabbit’s 

patchy habitat distribution across the 

landscape, as discussed earlier, the 

scope of loss or modification of 

sagebrush habitat in general due to 

agricultural conversion does not equally 

relate to the loss or modification of 

pygmy rabbit habitat. Based on 

information in site-specific areas, 

agricultural conversion has resulted in 

some loss of sagebrush habitat used by 

pygmy rabbits and likely has resulted in 

some localized population declines in 

areas of Idaho, Montana, California, 

Nevada, and Utah. 

As presented above, the examples of 

conversion of sagebrush habitat are few 

in number across the range and do not 

indicate a systematic or widespread loss 

of habitat that may have been or is now 

suitable for pygmy rabbits. While there 

has been some documented loss of 

historical pygmy rabbit sites due to 

agricultural conversion, the best 

available scientific information does not 

indicate a significant loss or 

modification of habitat, and 

measureable population decreases 

attributed to habitat loss or modification 

due to agriculture impacts are not 

occurring across the range. While 

sagebrush habitat will continue to be 

converted to agricultural lands in the 

future, it will occur at a much lower rate 

as much of the appropriate habitat has 

already been converted. Therefore, 

based on the best available scientific 

information, we conclude that 

sagebrush loss or modification due to 

agriculture is not a significant threat to 

the pygmy rabbit now or in the 

foreseeable future. 

Sagebrush Treatment 

Treatment of sagebrush by mechanical 

(mowing, rotobeating, roller chopping, 

grubbing, chaining, bulldozing, cabling, 

raking, railing, and plowing) and 

chemical methods (herbicide) primarily 

for rangeland improvement and grazing 

management to increase forage 

production for domestic and wild 

ungulates has been common in 

sagebrush ecosystems (Connelly et al. 

2004, pp. 7-46 to 7-47). Over 5 million 

ac (2 million ha) of sagebrush habitat 

was mechanically or chemically treated 

or burned by the 1970s (Crawford et al. 

2004, p. 12). According to Braun (1998, 

p. 9) mechanical treatments began in the 

1930s and continued at relatively low 

levels until the late 1990s. While many 

square miles of sagebrush habitat have 

been lost during the last 150 years due 

to conversion for agriculture (discussed 

above), today this conversion occurs at 

relatively low levels (70 FR 2255). 

Possible effects to pygmy rabbits of 

mechanical or chemical sagebrush 

treatments include injury or death at the 

time of treatment, reduction in forage 

and shelter, temporary or permanent 

home range abandonment, increased 

habitat fragmentation, increased 

dispersal barriers, increased predation, 

and population declines. As a sagebrush 

dependent species, complete loss of 

sagebrush in a large area could have 

long-term impacts to pygmy rabbits. 

Olterman and Verts (1972, p. 25) and 

Wilde (1978, p. 120) cautioned that the 

practice of sagebrush removal from 

some livestock ranges in Oregon and 

Idaho, respectively, could be a threat to 

the pygmy rabbit in the future. The 

researchers noted that land changes 

should be monitored and adequate 

‘‘safeguards’’ implemented to reduce 

excessive clearing of large areas. 

Roberts (1998, p. 11) calculated that of 

the 583,600 ac (236,180 ha) he 

inventoried for pygmy rabbit occupancy 

in Lemhi and Custer Counties, Idaho, 

49,000 ac (19,830 ha) (8 percent) were 

lost due to sagebrush eradication; 

Roberts (1998, p. 11) did not estimate 

the amount of lost pygmy rabbit habitat. 

In Oregon, BLM (2007b, pp. 5-6) 

documented active pygmy rabbit use at 

one of eight sites that had sagebrush 

strips removed by mowing. It appeared 

that pygmy rabbits had been there prior 

to the mowing (as evidenced by 

burrows), with residency continuing 

following mowing. Mowing may have 

opened the area for new growth of 

herbaceous vegetation which can be 

beneficial to pygmy rabbits (BLM 2007b, 

p. 7). 

In Montana, Rauscher (1997, pp. 13- 

14) reported that sagebrush removal was 

a ‘‘popular’’ rangeland improvement 

practice in the southwestern portion of 

the State. Sagebrush in the Coyote Creek 

area of the Big Sheep Creek Basin has 

been extensively treated, and only one 

active burrow was located. In nearby 

areas where sagebrush had not been 

treated, pygmy rabbits were more 

abundant. In lower Badger Gulch, BLM 

lands border private lands, and pygmy 

rabbits were found on the public lands 

but absent on the private lands where 

sagebrush had been removed. However, 

it is unclear how much sagebrush 

removal had occurred on the private 

lands and whether pygmy rabbits had 

previously occupied these same lands. 

In Wyoming, Katzner (1994, p. 106) 

mentioned that sagebrush eradication 

may have significant adverse effects on 

the pygmy rabbit where they were 

known to occur in southwestern 

Wyoming at that time. He recommended 

that if sagebrush management is 

‘‘mandated,’’ management plans should 

consider the pygmy rabbit and retain 

large patches of sagebrush or corridors 

connecting areas of suitable habitat. 

Welch (2005, p. 10) visited 13 

historical pygmy rabbit sites in Utah 

and Idaho. He indicated one site was no 

longer occupied by pygmy rabbits and 

had been impacted by range 

improvement. 

In Utah, Holt (1975, p. 159) 

mentioned a concern that removing 

large areas of sagebrush by chaining and 

spraying in order to plant grass would 

harm rabbits, including the pygmy 

rabbit. Flinders et al. (2005, p. 7) 

surveyed habitat in Grass Valley in 

Piute, Sevier, and Wayne Counties 

located in south central Utah. Pygmy 

rabbit surveys were conducted in areas 

slated for sagebrush treatment, but 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60536 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

where pygmy rabbit surveys had not 

been previously conducted. Areas 

where pretreatment pygmy rabbit 

surveys (Oak Springs and Praetor 

Slopes) had been completed by BLM 

employees (Flinders et al. 2005, p. 13) 

were revisited, as well. According to 

Flinders et al. (2005, p. 13), BLM 

surveys identified 118 active burrow 

systems and 85 inactive ones. Flinders 

et al. (2005, p. 13) found 14 locations 

with active burrow systems and 

determined all other burrows in 

treatment areas to be inactive. BLM 

surveyed sites recorded as active were 

found to be ‘‘abandoned’’ or plowed 

when revisited (Flinders et al. 2005, p. 

13). 

Where pygmy rabbits were still 

occupying treatment areas, they were in 

wide sections of sagebrush that was 

intact and connected to adjacent 

remaining sagebrush (Flinders et al. 

2005, p. 13). In undisturbed sagebrush, 

pygmy rabbits were in isolated patches 

(Flinders et al. 2005, p. 13). Flinders et 

al. (2005, p. 36) thought treatment 

projects could be beneficial to pygmy 

rabbits if the sagebrush stands were left 

in wide, connected corridors as this 

would provide forage as well as cover. 

BLM treatment areas revisited found 

active burrows only where the 

sagebrush treatment occurred in 

mosaics that were connected to other 

sagebrush stands or the areas of removal 

were much smaller and distances 

between the treatments were minimal. 

Patchy, smaller sagebrush removal more 

likely mimics the natural historical fire 

regime. Flinders (2007, p. 3) reported on 

his preliminary results from a multiyear pygmy rabbit study in Grass Valley, 

Utah and found a reduction in suitable 

pygmy rabbit habitat due to sagebrush 

treatments. He found pygmy rabbit 

activity was restricted to a narrow band 

adjacent to mature stands of sagebrush 

and showed significantly decreased 

activity within the treated areas. Burrow 

abandonment was noted following 

treatment, and he suggested a 131.2 ft 

(40 m) buffer between active burrows 

and habitat treatment. In Grass Valley, 

Piute and Sevier Counties, and Parker 

Mountain, Wayne County, Utah, Lee 

(2008, pp. 4, 7) found lower fecal pellet 

counts in mechanically-treated 

sagebrush areas as compared to 

untreated sagebrush areas. Average 

pygmy rabbit fecal pellet counts 

decreased with distance from sagebrush 

(Lee 2008, p. 10). Lee (2008, p. 11) 

recommended avoiding treatments of 

big sagebrush in areas occupied by 

pygmy rabbits and in areas with all 

suitable habitat conditions. If treatments 

cannot be avoided, they should leave 

intact large swaths of undisturbed 

mature big sagebrush (Lee 2008, p. 11). 

Lee (2008, p. 14) recommended that 

corridors between residual stands of 

sagebrush within a treatment area be 

maintained for connectivity and 

dispersal. Lee (2008, p. 13) 

recommended that stands of remaining 

mature big sagebrush be about 54 yd 

(490 m) across in any direction, and the 

areas of big sagebrush removed should 

be narrow (44 yd; 40 m). 

BLM has proposed a national program 

to treat vegetation across several 

western States to reduce hazardous 

fuels, control unwanted vegetation and 

improve habitat and resource conditions 

through the use of prescribed fire, 

wildland fire, herbicides, manual and 

mechanical methods, and biological 

controls (BLM 2007c, p. 1-3 Abstract, 

Executive Summary, Chapters 1 through 

7, and Appendices). BLM manages 

approximately 261 million ac (105.6 

million ha) in 17 western States 

including Alaska (BLM 2007c, p. 1-1 

Abstract, Executive Summary, Chapters 

1 through 7, and Appendices). States 

encompassing the range of the pygmy 

rabbit are included in this program. 

BLM estimated that 6 million ac 

(2,428,166.7 ha) of vegetation would 

need to be treated annually over the 

next 10 years (BLM 2007c, p. 1-7 

Abstract, Executive Summary, Chapters 

1 through 7, and Appendices). 

Estimated acres treated annually by the 

various methods include: 2.2 million ac 

(890,327.8 ha) by mechanical means; 2.1 

million ac (849,858.4 ha) by fire; 

932,000 ac (377,175.2 ha) by herbicides; 

454,000 ac (183,731.3 ha) by biological 

control; and 271,000 ac (109,672.2 ha) 

by manual means (BLM 2007c, p. ES-2 

Abstract, Executive Summary, Chapters 

1 through 7, and Appendices). The 

implementation of this program, 

methods, acres treated, and locations are 

yet to be determined. 

Summary of Sagebrush Treatment 

Impacts 

Although loss of sagebrush due to 

sagebrush treatment for rangeland and 

grazing management in specific portions 

of the pygmy rabbit’s range has been 

documented, the examples presented 

above are few in number across the 

range and are not indicative of a 

systematic or widespread loss of habitat 

that may have been or is now suitable 

for pygmy rabbits. Because of the pygmy 

rabbit’s patchy habitat distribution 

across the landscape, the scope of loss 

or modification of sagebrush habitat in 

general due to treatments does not 

equally relate to loss or modification of 

pygmy rabbit habitat. Sagebrush 

treatment has been documented to be 

responsible for loss of sagebrush habitat 

used by pygmy rabbits in a few specific 

areas of Oregon, Idaho, Montana, 

Wyoming, Utah and may have resulted 

in localized population declines. The 

known presence of pygmy rabbits prior 

to treatment is not documented in all 

cases and some areas show continued 

occupancy or use by pygmy rabbits at 

some level after treatments were 

conducted (e.g. Flinders et al. 2005; Lee 

2008). 

Depending on the design and size of 

the sagebrush treatment, impacts to 

pygmy rabbits may be minimized, and 

if designed appropriately, sagebrush 

treatments may be beneficial to pygmy 

rabbits. We are aware of a BLM proposal 

to implement sagebrush treatments that 

could impact sagebrush habitat in the 

western United States, however no 

actions have been implemented at this 

time (BLM 2007c). Available 

information indicates that a significant 

loss or modification of habitat, and 

measureable population decreases 

attributed to habitat loss or modification 

due to treatment impacts and impacts to 

the pygmy rabbit with regard to injury 

or death, temporary home range 

abandonment or permanent shift to 

adjacent areas, habitat fragmentation, or 

increased predation are not occurring 

across the range. Therefore, based on the 

best available scientific and commercial 

information, we conclude that 

sagebrush loss or modification due to 

treatments is not a significant threat to 

the pygmy rabbit now or in the 

foreseeable future. 

Livestock Grazing 

Livestock grazing is the most 

widespread land use type across 

sagebrush communities (Connelly et al. 

2004, p. 7-29). Excessive grazing by 

domestic livestock during the late 1800s 

and early 1900s, along with severe 

drought, significantly impacted 

sagebrush ecosystems and the long-term 

effects involving plant community and 

soil changes, continue today (Yensen 

1981, cited in Knick et al. (2003, p. 616). 

By the 1940s, animal unit months 

(AUM) on all Federal lands were 

estimated to be 14.6 million, increasing 

to 16.5 million in the 1950s, however 

estimated AUMs decreased to 10.2 

million by the 1990s (Miller and 

Eddleman 2001, p. 19). Grazing impacts 

may be associated with the direct loss 

of sagebrush vegetation through 

physical damage by rubbing, battering, 

breaking and trampling of seedlings, or 

habitat degradation due to associated 

facilities or actions such as: 

construction of fences; wells; water 

tanks; pipelines which concentrate 

livestock or redistribute livestock; 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60537 

seeding of crested wheatgrass to 

increase livestock forage; and weed 

infestations. 

Impacts of livestock grazing on the 

arid west include selective grazing for 

native species, trampling of plants and 

soil, damage to soil crusts, reduction of 

mycorrhizae fungi, increases in soil 

nitrogen, increases in fire frequency, 

and contribution to nonnative plant 

introductions (Belsky and Gelbard 

(2000, pp. 12-18); Paige and Ritter 

(1999, pp. 7-8)). When sagebrush-grass 

habitats are overgrazed, native perennial 

grasses can be eliminated, and shrubs, 

such as big sagebrush, tend to form 

dense monotypic (single species) stands 

(Blaisdell 1949, cited in Yensen 1982, p. 

25; Tisdale and Hironaka 1981, cited in 

Paige and Ritter 1999, p. 7). In addition, 

the understory becomes sparse with 

unpalatable perennials (Tisdale and 

Hironaka 1981, cited in Paige and Ritter 

1999, p. 7) and invasions of annual 

species like Bromus tectorum 

(cheatgrass) can occur (Gabler 1997, p. 

96; Rauscher 1997, p. 14). Reduction of 

native grasses and increases in invasive 

plant species may reduce habitat quality 

and suitability for pygmy rabbits by 

reducing summer forage and impeding 

their movements or ability to see 

predators. 

Possible effects of livestock grazing 

include direct injury or death due to 

trampling, degradation of sagebrush 

plant structure resulting in reduced 

forage and shelter, habitat 

fragmentation, increased predation, 

reduced grasses and forbs resulting in 

loss of summer forage, increased visual 

capabilities and ease of movement, 

trampling of burrows, increased 

invasive plant species resulting in 

reduced visual capabilities and ease of 

movement, and population declines. 

However, livestock grazing in pygmy 

rabbit habitat has been noted in the 

early literature. For example, Dice 

(1926, p. 27) in Oregon, found pygmy 

rabbits near Baker in an area that was 

overgrazed by domestic sheep. He stated 

very little vegetation remained except 

for sagebrush and rabbit brush. The 

patch of habitat being used was about 

300 yd long (274.2 m) by 50 yd (45.7 m) 

wide and was surrounded by low 

sagebrush (Dice 1926, p 27). 

Flath and Rauscher (1995, p. 2) and 

Purcell (2006, p. 33) found that areas of 

tall, dense sagebrush inhabited by 

pygmy rabbits were typically located 

along streams. Livestock can impact 

these areas disproportionately by 

concentrating in riparian areas where 

trampling and vegetation removal can 

occur (Red Willow Research Inc. 2002, 

p. 107). These researchers do not 

indicate any specific pygmy rabbit 

locations along streams that have been 

impacted by livestock grazing. 

In Oregon, Hager and Lienkaemper 

(2007, p. 6) reported that all 157 sites, 

located mostly on State lands, surveyed 

for pygmy rabbits had evidence of cattle 

grazing. Many areas showed heavy use 

by cattle which had resulted in a 

decrease in shrub cover. Additionally, 

many of the areas where no evidence of 

pygmy rabbit presence was found may 

have had potential to support pygmy 

rabbits, as predicted by a habitat model, 

but the habitat may have been rendered 

unsuitable due to grazing reducing 

shrub cover (Hager and Lienkaemper 

2007, p. 6). However, it is unknown 

whether pygmy rabbits were present 

previously or were absent from these 

areas based on other factors. The BLM 

(2007b, p. 4) reported livestock use at 

one of eight occupied sites surveyed in 

Oregon. 

In Idaho, Red Willow Research Inc. 

(2000, p. 8) documented pygmy rabbit 

sightings on two separate BLM grazing 

allotments which demonstrated 

historical and current grazing activities. 

Another sighting occurred on private 

land subjected to grazing and was also 

close to dwellings and agricultural 

activities (Red Willow Research Inc. 

2000, pp. 8, 11). In Idaho, Roberts (2001, 

p. 18) concluded that there was no clear 

evidence that livestock grazing is 

detrimental to pygmy rabbits. In Idaho, 

White and Bartels (2002, pp. 6, 15) 

surveyed 11 grazing allotments. Of the 

6 allotments where pygmy rabbit sign 

was observed, 2 allotments supported 

active burrows, 2 allotments contained 

inactive burrows, and 2 allotments 

supported burrows of undetermined 

status. BLM (2005a, p. 2) found during 

their surveys, conducted between 2002 

and 2005 that pygmy rabbits occurred 

on their lands containing portions of 

grazing allotments. In Idaho, North 

Wind (2004, p. 12) mentioned livestock 

grazing occurred in all areas where 

pygmy rabbit sign or sightings occurred. 

In Idaho, Waterbury (2005, p. 9) 

mentioned that an occupied site where 

a pygmy rabbit was observed (Goldburg 

site) in the upper Pahsimeroi Valley was 

subjected to livestock grazing. 

In Montana, Rauscher (1997, pp. 14, 

17) found that most pygmy rabbit sites 

were grazed to some extent. Pygmy 

rabbits were found to be ‘‘surviving and 

even thriving’’ at current grazing levels 

in certain areas. 

In Wyoming, Katzner reported that 

according to Dorn et al. (1984, cited in 

Katzner 1994, p. 5), pygmy rabbits did 

not occur in his study area (Historical 

Quarry Trail region) at Fossil Butte 

National Monument, Lincoln County in 

1983 at the time when domestic 

livestock grazing was terminated in the 

monument. Katzner and Parker (1997, p. 

1071) stated that the apparent 

dependence of pygmy rabbits on a dense 

understory, provided in part by dead 

shrubs and extensive canopies, may 

explain population declines in the 

pygmy rabbit in grazed sagebrushsteppe habitat in the western United 

States. Lands grazed intensively by 

domestic herbivores often have 

relatively low structural complexity and 

may not support pygmy rabbit 

populations adequately. The physical 

destruction of dense, structurallydiverse patches of sagebrush, and the 

corridors that connect them, result in 

fragmented, unsuitable big sagebrush 

habitat for pygmy rabbits (Katzner and 

Parker 1997, p. 1071). For a species that 

eludes predators in sagebrush habitat, a 

reduction in canopy cover would 

increase the vulnerability of pygmy 

rabbits to predation (Bailey 1936, p. 111; 

Orr 1940, p. 197; Wilde 1978, pp. 115- 

116; Katzner 1994, pp. 50, 52-53). Clark 

and Stromberg (1987, p. 76) remarked 

that overgrazing, which has increased 

the sagebrush-grass ratio, may decrease 

pygmy rabbit populations. 

In Nevada and California, Larrucea 

(2006 p. 8) stated that livestock grazing 

at inappropriate levels can be 

detrimental for the degradation of 

sagebrush habitat. At reasonable levels 

it may be beneficial (Larrucea 2006, p. 

8; Larrucea 2007, p. 34). Most of the 

pygmy rabbit burrows on the BLM lands 

in the Surprise FO were in areas 

available to grazing (Larrucea 2006, p. 

8). In Nevada and California, Larrucea 

and Brussard (2008b, p. 1638) found 

cattle grazing occurred at 83 percent of 

historical pygmy rabbit sites; 38 percent 

showed current pygmy rabbit activity. If 

sites with additional impacts were 

eliminated and only cattle grazing 

impacts are considered, this increased 

to 62 percent of sites that supported 

current pygmy rabbit activity (Larrucea 

and Brussard 2008b, p. 1639). Grazing 

was compatible with pygmy rabbits if 

grazing occurs at levels that left 

sagebrush plants intact and soils were 

not overly compacted (Larrucea 2007, p. 

58). Larrucea and Brussard (2008a, p. 

697) found increasing amounts of 

understory stem density was associated 

negatively with current pygmy rabbit 

presence at a site. Pygmy rabbits, by 

foraging for forbs and grasses near their 

burrows, may create areas of little 

understory. An understory that is free of 

grasses and forbs may be beneficial by 

reducing movement restrictions and 

increasing pygmy rabbit’s ability to 

detect predators (Weiss and Verts 1984, 

p. 568). The Southern Nevada Water 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60538 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Authority (SNWA) (2008, p. 15) stated 

that data collected during their surveys 

conducted in 2005 and 2006 in Nevada 

(SNWA 2007, entirety) found 84 percent 

of the sites with documented pygmy 

rabbit occurrence existed in areas of 

moderate grazing. SNWA (2008, p. 15) 

suggested that given that recent 

occurrence data overlaps with grazing 

practices, there is little evidence to 

suggest that light to moderate grazing is 

significantly detrimental to pygmy 

rabbit in Nevada. 

In Utah, Janson (2002, p. 31) did not 

attempt to measure grazing intensity 

during his earlier studies. While he 

observed a scarcity of grasses and forbs 

in the Cedar City area compared to the 

Blue Springs area, efforts to collect and 

observe pygmy rabbits seemed to be 

similar on either site. The difference 

between the amount of shrubs to 

herbaceous vegetation between the two 

sites, due to grazing or some other 

factor, did not seem to affect the 

populations. He did state that grazing 

intensities high enough to break down 

the sagebrush plants and reduce their 

density would be detrimental to pygmy 

rabbits. Although it is unclear how 

many of the four sites he considered 

overgrazed, Larsen et al. (2006, p. 5) 

found historical pygmy rabbit sites in 

Tooele County, Utah that showed 

evidence of overgrazing. 

Trampling of burrows by livestock has 

been reported in Montana by Rauscher 

(1997, p. 14) and in Idaho by Red 

Willow Research Inc. (2002, p. 54). This 

could cause the death of young rabbits 

in natal burrows or injury or death of 

adults. Red Willow Research Inc., (2002, 

pp. 54-55) reported a burrow system in 

Idaho that was subjected to cattle 

trailing on at least two separate 

occasions within a period of two 

months or less. After the initial event, 

only two of ten active burrows were still 

open. A second visit showed additional 

trailing activities, and no open burrows 

or recent sign were found, indicating 

‘‘that domestic livestock can have an 

immediate and detrimental effect upon 

burrow systems’’ (Red Willow Research 

Inc., 2002, pp. 54). This assumes that no 

other influences were involved, and 

there was no further monitoring of the 

area to determine if pygmy rabbits 

returned to the area at a later date. 

Summary of Livestock Grazing Impacts 

Livestock grazing occurs in all seven 

States where pygmy rabbits occur. 

Researchers suggest that livestock 

grazing, particularly overgrazing, may 

negatively impact some sagebrush 

habitat used by pygmy rabbits and may 

result in some localized population 

declines. The potential effects of 

livestock grazing on sagebrush habitat 

and pygmy rabbit populations, while 

widespread across the pygmy rabbit’s 

range have not been documented to 

impact pygmy rabbits at the population 

level or result in documented 

measurable population declines as a 

result of overgrazing. 

As described above, there are several 

examples where pygmy rabbits have 

been document to continue to occupy 

areas grazed by livestock, which may 

indicate an apparent compatibility 

between livestock grazing and area use 

by pygmy rabbits under certain grazing 

conditions. Other documentation 

suggests possible habitat loss or 

degradation, site abandonment, habitat 

fragmentation, increased predation, or 

injury of pygmy rabbits due to livestock 

overgrazing and trampling. However, 

based on survey information, there is no 

indication of a causal relationship 

between livestock grazing and pygmy 

rabbit site abandonment or avoidance. 

Studies do not indicate that there is a 

level of livestock grazing that influences 

pygmy rabbit site occupancy. While the 

Service is aware of a report of burrow 

trampling, we are not aware of any 

studies relating actual site 

abandonment, increased predation, 

death, or injury due to livestock grazing 

or trampling. Reduced grasses and forbs 

may increase the pygmy rabbits’ ability 

to see and evade predators. Some survey 

reports suggest that livestock grazing is 

degrading pygmy rabbit habitat in some 

locations. Our review of the best 

available scientific data indicate that 

measureable population decreases 

attributed to habitat modifications from 

livestock grazing are not occurring 

across the range. Therefore, we 

conclude that livestock grazing is not a 

significant threat to the pygmy rabbit 

now or in the foreseeable future. 

Nonnative Invasive Plants 

Paige and Ritter (1999, p. 8) suggest 

that the greatest change to sagebrush 

shrub lands has been the invasion of the 

nonnative grasses and forbs, especially 

cheatgrass. Cheatgrass is a rapid 

colonizer of disturbed areas and is 

persistent in replacing native species 

(Mack 1981, Yensen 1981, and 

Whisenant 1990, cited in Paige and 

Ritter 1999, p. 8). Cheatgrass alters fire 

and vegetation patterns in sagebrush 

habitats as it creates a continuous fine 

fuel that easily carries fire (Paige and 

Ritter 1999, p. 8). Where it dominates, 

it can carry fires over large distances, 

and it burns more frequently than native 

vegetation (Paige and Ritter 1999, p. 8). 

It also matures and dries earlier than 

native vegetation, increasing the 

likelihood of a fire earlier in the season 

(Young and Evans 1978, Whisenant 

1990, and Knick and Rotenberry 1997, 

cited in Paige and Ritter 1999, p. 8). 

The total acreage of invasive plant 

infestations has been reported with 

varying estimates. Pellant and Hall 

(1994, p. 109) reported on the 1992 

distribution of cheatgrass and 

Taeniatherum asperum (medusa head), 

the primary alien grass invaders of 

disturbed and fire-altered rangelands in 

the Intermountain area of the western 

United States. Approximately 3.3 

million ac (1.3 million ha) of rangeland 

administered by the BLM in Nevada, 

Oregon, Utah, Washington, and Idaho 

are dominated by these two species 

(Pellant and Hall 1994, p. 109). Another 

76.1 million ac (30.8 million ha) of 

public rangeland was classified as 

infested or susceptible to infestation by 

these two species (Pellant and Hall 

1994, p. 109). It has been estimated that 

3 million ac (1.2 million ha) of public 

lands in the Great Basin have been 

converted to a cheatgrass monoculture 

with another 14 million ac (5.7 million 

ha) assumed to be infested, and it is 

likely that conversion is inevitable 

(Knapp 1996, West 1999, cited in 

Larrucea 2007, p. 61). Though estimates 

of total area supporting cheatgrass vary 

widely, cheatgrass is a significant 

presence in western rangelands (75 FR 

13935). 

BLM (1996, p. 6) estimated invasive 

plant species covered at least 8 million 

ac (3.2 million ha) of BLM lands as of 

1994 and predicted 19 million ac (7.7 

million ha) would be infested by 2000. 

A qualitative BLM survey in 1991 

covering 98.8 million ac (40 million ha) 

of BLM-managed land in Washington, 

Oregon, Idaho, Nevada, and Utah 

reported introduced annual grasses were 

a dominant or significant presence on 

17.2 million ac (7 million ha) of 

sagebrush ecosystems (Connelly et al. 

2004, pp. 5-10). In reference to the same 

BLM survey, Zouhar (2003, p. 3 cited in 

75 FR 13935) estimated an additional 62 

million ac (25 million ha) had less than 

10 percent cheatgrass understory, but 

were considered to be a risk of 

cheatgrass invasion. BLM has reported 

that as of 2000, invasive plants occupied 

about 29 million ac (11.7 million ha) of 

BLM lands in the Washington, Oregon, 

Idaho, Utah, Nevada (BLM 2007a, pp. 3- 

28 as cited in 75 FR 13935). 

Connelly et al. (2004, p. 7-15) 

estimated the risk of cheatgrass invasion 

into sagebrush and other natural 

vegetation in a portion of the southern 

and northern Great Basin. They 

projected, based on elevation, landform, 

and south-facing slope parameters, that 

80 percent of the land area in the Great 

Basin is susceptible to displacement by 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60539 

cheatgrass and of that area, greater than 

65 percent is estimated to be at 

moderate or high risk within 30 years 

(Connelly et al. 2004, pp. 7-16 to 7-17). 

Wyoming-basin big sagebrush and salt 

desert scrub, which occupy over 40 

percent of the Great Basin, are the 

vegetation types most susceptible to 

cheatgrass displacement (Connelly et al. 

2004, p. 7-17). 

Restoration or rehabilitation of areas 

to sagebrush after invasive plant 

species, especially annual grasses, 

become established is difficult. Only 

about 3 to 34 percent of recent 

vegetation treatments performed by 

BLM in areas of annual grassland 

monocultures were successful (Carlson 

2008b, pers. comm., cited in 75 FR 

13937). The success of treatments often 

depends on factors such as precipitation 

received at the treatment site (Pyke, in 

press, p. 30). 

Nonnative invasive plant species may 

impact pygmy rabbits throughout their 

range by replacing native grasses and 

shrubs used by pygmy rabbits, 

hindering their ability to see or move, 

and increasing detection by predators. 

In Oregon, only 2 of 51 sites occupied 

by pygmy rabbits in 1982 contained 

appreciable amounts of cheatgrass 

(Weiss and Verts 1984, p. 568). This led 

the authors to suspect that pygmy 

rabbits avoid areas containing annual 

grasses because it can restrict their 

movements or ability to see, especially 

when they are attempting to escape 

predators. However, it is unclear 

whether annual grasses are playing a 

role in pygmy rabbits not occupying a 

site. The authors did not indicate 

whether or not unoccupied sites 

surveyed had cheatgrass. 

In Idaho, invasive plants were 

reported at all nine study areas 

investigated by Red Willow Research 

Inc. (2002, pp. 38, 45, 59, 65, 72, 80, 87, 

92, 97). Gabler (1997, p. 94) predicted 

10 study sites would be used by pygmy 

rabbits, but later found large patches of 

cheatgrass on 8 of those sites, and that 

the pygmy rabbit did not use these sites. 

Other factors, such as large amounts of 

dead sagebrush, and/or sparse, short 

sagebrush, and thick grass cover, may 

have contributed to pygmy rabbit 

absence in those sites (Gabler (1997, p. 

94). BLM (2005a, p. 2) indicated that no 

evidence of pygmy rabbits was found at 

any of the sites (no number provided) in 

Idaho surveyed in 2005 where 

cheatgrass was a major component of 

the understory. Burak (2006, p. 68) 

found that cheatgrass made up little of 

the grass community within his entire 

study area; areas occupied by pygmy 

rabbit had approximately 1 percent 

cheatgrass cover and unoccupied areas 

had less than 1 percent. 

In Nevada and California, Larrucea 

and Brussard (2008b, p. 1641) stated 

that wide expanses of cheatgrass 

monocultures may provide a barrier to 

pygmy rabbit dispersal as they rely on 

shrub cover for protection from 

predators. Larrucea and Brussard 

(2008a, p. 697) found cheatgrass 

presence was negatively associated with 

pygmy rabbit presence at a site. Once 

established it may be difficult for pygmy 

rabbits to burrow into the dense root 

mats (Larrucea and Brussard 2008a, p. 

697). SNWA overlaid a Nevada Natural 

Heritage Program invasive annual grass 

index map (most of which was 

cheatgrass) (NHP 2006, cited in SNWA 

2008, p. 14) with 2000 to 2007 pygmy 

rabbit occurrence data from various 

sources. The overlay indicates a large 

portion of pygmy rabbit occurrences are 

within areas of relatively low cheatgrass 

cover. This map serves as a relative 

density index of cheatgrass rather than 

actual current ground cover because of 

the remote sensing and statistical 

models from which it is derived. While 

the underlying models tend to 

underestimate index values for sites 

with high invasive annual grass 

densities, the general pattern of low to 

high densities is well represented on the 

map. The map is quite accurate for sites 

where invasive annual grass cover is 

low or nonexistent. SNWA concluded 

that cheatgrass has not had a major 

impact on pygmy rabbit occurrence or 

geographic range in east-central Nevada 

(SNWA 2008, p. 14). 

Larsen et al. (2006, p. 5) visited four 

historical pygmy rabbit sites in Tooele 

County, Utah that were unoccupied by 

pygmy rabbits. They mentioned these 

sites showed evidence of cheatgrass 

invasion, but it is unclear if all four sites 

supported cheatgrass. 

Summary of Nonnative Invasive Plant 

Impacts 

Based on information for a few 

specific areas, presence of invasive 

plant species has been documented and 

may have some impact on pygmy rabbit 

presence or their movements in Oregon, 

Idaho, Nevada, California, and Utah. 

These examples, as discussed above, are 

few in number and are not considered 

to be indicative of a widespread habitat 

condition. It is unclear whether the 

presence of cheatgrass or other invasive 

plant species caused pygmy rabbits to 

not occupy an area or if other factors 

may have also played a role. The scope 

of loss or modification of sagebrush 

habitat in general due to nonnative 

plant invasion does not equally relate to 

the loss or modification of pygmy rabbit 

habitat because pygmy rabbit’s habitat is 

patchily distributed across the 

landscape. 

Varying estimates have been made 

regarding the amount of area invaded by 

invasive plant species in the western 

United States, and some predictions 

indicate it could take decades for 

cheatgrass to invade sagebrush and 

other natural vegetation in a portion of 

the Great Basin. The Service recognizes 

that invasion of sagebrush habitat by 

nonnative plant species is a concern 

based on their ability to outcompete 

sagebrush, the difficulty in controlling 

them once established, and their 

interaction with other threats, such as 

fire. However, there is no indication of 

a significant loss or modification of 

habitat, and measureable population 

decreases attributed to habitat loss or 

modification due to nonnative plant 

species, especially cheatgrass, and 

pygmy rabbit site abandonment or 

avoidance are not occurring across the 

range. Available information does not 

provide a causal relationship between a 

reduction in pygmy rabbit visual 

capabilities and ease of movement due 

to nonnative plant species. Therefore, 

based on the best available scientific 

and commercial information, we 

conclude that nonnative invasive plant 

species in pygmy rabbit habitat is not a 

significant threat to the pygmy rabbit 

now or in the foreseeable future. 

Fire 

The effect of fire on sagebrush 

habitats depend on the sagebrush 

species present, the composition of 

understory species, and the size, 

frequency, and intensity of the fire. 

Estimates of mean fire intervals 

indicated in the literature vary widely: 

12 to 15 years for mountain big 

sagebrush (Miller and Rose 1999, p. 

556), 13 to 25 years (Frost 1998, cited 

in Connelly et al. 2004, p. 7-4), greater 

than 50 years for big sagebrush 

communities (Whisenant 1990, cited in 

McArthur 1994, p. 347), 20 to 100 years 

(Peters and Bunting 1994, p. 33), 35 to 

100 years (USFS 2000, p. 7), and 10 to 

110 years depending on sagebrush 

species and geographic area (Kilpatrick 

2000, p. 1). 

Natural fires in sagebrush stands 

characteristically result in incomplete 

burns leaving areas of unburned 

sagebrush (Huff and Smith 2000, cited 

in 70 FR 2264). These unburned areas 

appear to be important in the future 

recolonization of the sagebrush 

community by providing sources of 

sagebrush seed (Huff and Smith 2000, 

cited in 70 FR 2264). Prior to European 

immigrant settlement, fire patterns in 

sagebrush communities were patchy, 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60540 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

particularly in Wyoming big sagebrush, 

due to the limited and discontinuous 

fuels and unburned areas that remained 

after a fire (Miller and Eddleman 2001, 

p. 17). 

In parts of the Great Basin, a decline 

in fire occurrence since the late 1800’s 

has been reported in several studies 

coinciding with fire suppression and 

reduction of fuels by introduced 

livestock (Miller and Rose 1999, pp. 

556-557; Kilpatrick 2000, p. 6; Connelly 

et al. 2004, p. 7-5). Long fire intervals 

and fire suppression can result in 

increased dominance of conifer species, 

such as western juniper (Juniperus 

occidentalis) (Wrobleski and Kauffman 

2003, p. 82) resulting in almost 

complete loss of shrubs in localized 

areas (Miller and Eddleman 2001, p. 20). 

Burning can also damage perennial 

grasses, allowing cheatgrass to increase 

(Stewart and Hull 1949; Wright and 

Britton 1976, cited in Yensen 1982, p. 

28). The presence of cheatgrass extends 

the fire season and carries a fire into 

areas where burning would not 

normally occur or can make fires 

difficult to control (Yensen 1982, pp. 

28-29; Billings 1994, p. 24). The 

invasion of nonnative annuals, such as 

cheatgrass and medusa head has 

resulted in increases in the frequency 

and number of fires within sagebrush 

habitats (USFS 2000, p. 153; Connelly et 

al. 2004, pp. 5-9 to 5-10). Sagebrush 

does not quickly re-establish after fires, 

while nonnative grasses can recover 

quickly and increase, effectively 

preventing sagebrush return. Due to this 

relationship between fire and the spread 

of invasive plants, large areas of 

sagebrush in the western United States 

have been converted to cheatgrass 

(Connelly et al. 2004, p. 7-14). 

Generally, fire tends to extensively 

reduce the sagebrush component within 

the burned areas. The most widespread 

species of sagebrush, big sagebrush (A. 

tridentata spp.) (McArthur 1994, p. 

347), is killed by fire. It does not resprout after burning (Agee 1994, p. 14; 

Braun 1998, p. 9) and can take over 30 

years to recolonize an area (Wambolt et 

al. 2001, pp. 244, 247). Depending on 

the species, sagebrush can reestablish 

itself within 5 years of a burn, but it 

may take 15 to 30 years to return to preburn densities (Bunting 1984; and 

Britton and Clark 1984, cited in Paige 

and Ritter 1999, p. 6). Billings (1994, p. 

26) documented slow shrub succession 

following a burn in western Nevada, 

with little sagebrush recovery after 45 

years. This suggests that these sagebrush 

subspecies evolved in an environment 

where wildfire was infrequent (30 to 50 

year intervals) and patchy in 

distribution (Braun 1998, p. 9). 

Connelly et al. (2004, p. 7-6) 

summarized fire statistics from records 

of wild and prescribed fires in the 

sagebrush biome and found the total 

area burned and the number of fires 

increased from 1960 to 2003. In the 100 

million ac (40.5 million ha) sagebrushsteppe ecoregion or drier sagebrush 

areas, fire regimes have become more 

frequent (USFS 2000, p. 195). Miller et 

al. (2008, p. 39) also mapped fires from 

1960 through 2007 and found that the 

number of fires and total area burned 

across the Greater Sage-grouse 

Conservation Area increased in each of 

the geographic subdivisions except the 

Snake River Plain from 1980 through 

2007. Average fire size increased only in 

the Southern Great Basin during this 

period. Location of fires since 1960 was 

related to cheatgrass distribution 

particularly within the Snake River 

Plain and Northern Great Basin (Miller 

et al. 2008, p. 39). 

Wildfires have removed large areas of 

sagebrush in recent years. Although fire 

occurs throughout the sagebrush 

ecosystem, fire has disproportionately 

affected Idaho, Nevada, Oregon, and 

Utah (Baker, in press, p. 20). In these 

states combined, about 27 percent of the 

sagebrush habitat has burned since 1980 

(Baker, in press, p. 43). Total area 

burned each year on or adjacent to BLMadministered lands was variable from 

1997 through 2006 (Miller et al. 2008, 

pp. 39-40); most total area burned was 

in cheatgrass regions in Oregon, Idaho, 

and Nevada (Miller et al. 2008, p. 40). 

A number of fires have occurred in 

Idaho that have exceeded 100,000 ac 

(40,469 ha) (Roberts 2003a, p. 14). The 

largest contiguous patch of sagebrush 

habitat in southern Idaho covered about 

700,000 ac (283,000 ha) (Michael 

Pellant, BLM, quoted in Healy 2001, p. 

3), and during 1999 to 2001 about 

500,000 ac (202,000 ha) of this area 

burned. In Nevada, 1,277 fires in 2001 

impacted 654,253 ac (264,773 ha) on 

public and private lands (BLM 2001, p. 

3). In 2002, BLM reported 771 fires that 

impacted 77,551 ac (31,384 ha) on 

public and private lands in Nevada 

(BLM 2002, p. 3). In 2006, over 988,400 

ac (400,000 ha) of sagebrush steppe and 

potential pygmy rabbit habitat was 

burned in Elko County (Larrucea and 

Brussard 2008b, p. 1641). Over 9 fire 

seasons in Nevada (1999-2007), about 

2.5 million ac (1.0 million ha) of 

sagebrush habitat were burned. This 

represents about 12 percent of the extant 

sagebrush in Nevada (Espinosa and 

Phenix 2008, p. 3). Most of these fires 

occurred in northeast Nevada (75 FR 

13933). The amount of occupied pygmy 

rabbit habitat impacted by these fires is 

unknown. 

Sagebrush restoration efforts 

following fire are complicated by 

invasive, nonnative, annual plant 

species, costs, equipment limitations, 

availability of suitable seeds, limited 

knowledge of appropriate methods, and 

abiotic factors (Hemstrom et al., 2002, 

pp. 1250-1251, Pyke, in press, p. 29). 

Habitat rehabilitation following fire has 

increased in recent years from 69,436 ac 

(28,100 ha) in 1997 to 3.9 million ac (1.6 

million ha) in 2002 with treatments 

primarily occurring in Oregon, Idaho, 

and Nevada (Connelly et al. 2004, p. 7- 

35). While not all burned habitat is 

rehabilitated, fires which occur on 

public lands will likely experience some 

level of post-fire restoration (75 FR 

13934). 

Fire, either wild or prescribed, has 

been documented within the range of 

the pygmy rabbit and could result in 

long-term habitat loss or modification of 

pygmy rabbit habitat across its range. 

Possible impacts to pygmy rabbits 

include injury or death, reduction in 

forage and shelter, increased habitat 

fragmentation, increased predation, 

barriers to movement, or home range 

abandonment. Although information is 

available relating fire and its impact to 

pygmy rabbits, several studies have 

shown pygmy rabbit presence after fires. 

In Idaho, researchers have noted burn 

areas on the lands they have surveyed 

for pygmy rabbits. For example, Roberts 

(1998, p. 11) stated that of the 583,600 

ac (236,175 ha) he inventoried, about 

2,500 ac (1,012 ha) had been 

temporarily removed due to fire (a loss 

of 0.4 percent). White and Bartels (2002, 

pp. 8-9) indicated of the 133,067 ac (53, 

851 ha) they surveyed, 23,660 ac (9,575 

ha) had been affected by wildfire within 

the last 15 years and that historical 

pygmy rabbit locations had been 

impacted. The sagebrush had been 

burned and habitat for the pygmy rabbit 

was not available. In these studies, 

researchers did not indicate how much 

of this acreage might have been 

occupied by pygmy rabbits and the 

number of historical sites where habitat 

may have been removed is unknown. 

However, Welch (2005, p. 10) visited 

historical pygmy rabbit sites in Utah 

and Idaho and documented some sites 

(2 of 13) were, or were likely impacted 

by fire. 

Other researchers have reported 

impacts of fire on local pygmy rabbit 

populations. For example, Gates and 

Eng (1984, cited in Tesky 1994, p. 8) 

reported the deaths of ‘‘several’’ pygmy 

rabbits in an area where the fire 

advanced rapidly within a prescribed 

burn in Idaho. They thought pygmy 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60541 

rabbits may be capable of escaping slowmoving fires but could be burned or die 

of asphyxiation in others (Gates and Eng 

1984, cited in Tesky 1994, p. 8). Gates 

and Eng (1984, cited in Tesky 1994, p. 

9) also reported that 2 months following 

a fire in big sagebrush-grassland 

community, only 3 of 11 radio-collared 

pygmy rabbits were alive. Of the eight 

lost, seven were due to predation. They 

speculated that the loss of big sagebrush 

from their home ranges probably 

increased vulnerability to predation. 

Some of the surviving pygmy rabbits 

(presumably other uncollared pygmy 

rabbits) abandoned their home ranges 

and moved to new home ranges in 

adjacent unburned sites (Gates and Eng 

1984, cited in Tesky 1994, p. 9). Roberts 

(2001, p. 17) mentioned a 1966 burn 

near Gilmore Summit, Idaho, that had 

not regenerated to suitable habitat, and 

pygmy rabbits had not recolonized the 

area. Rachlow and Witham (2006, p. 6) 

suggested that large fires that removed 

sagebrush in the Camas Prairie of south 

central Idaho near the locations of 

known populations may reduce or 

eliminate successful movement of 

pygmy rabbits among some populations. 

In Nevada, the Service (1995, p. 2) 

reported that a survey conducted after a 

prescribed fire on the Sheldon National 

Wildlife Refuge in an area previously 

inhabited by pygmy rabbits found no 

evidence of their use afterwards. 

Larrucea (2006, p. 5) found no active 

pygmy rabbit sites in areas burned 

between 1981 and 2002 within the 

Surprise FO boundary; however, few 

fires occurred, and they were small in 

size (Figure 5 in Larrucea 2006, p. 14). 

Larrucea and Brussard (2008b, p. 1641) 

found 16 percent of the 105 historical 

pygmy rabbit sites in Nevada and 

California had been impacted by fire. 

Larrucea (2007, p. 61) found fire to be 

the strongest predictor of loss of pygmy 

rabbits from a site in Nevada and 

California; the greater the fire’s 

intensity, the fewer the patches of intact 

sagebrush will remain. Pygmy rabbits 

were found on the edges of large burned 

areas (Midas-Tuscarora Road, NV), but 

the burned areas had not reverted to 

suitable pygmy rabbit habitat (Larrucea 

2007, pp. 61-62). 

In contrast to the above studies, other 

researchers have mentioned burned 

areas that showed use by pygmy rabbits. 

In Idaho, a pygmy rabbit sighting 

reported by Red Willow Research Inc. 

(2000, p. 8) on BLM lands that had been 

impacted by wildfire in 1999 showed 

active use of the site. White and Bartels 

(2002, p. 13) mentioned that wildfires in 

the 1990’s severely affected the pygmy 

rabbit population, though some 

individuals remained. At one of her 

study sites, Waterbury (2005, p. 11) 

found occupied burrows in an area 

where prescribed burns had occurred 

during 1993 to 1995. Waterbury (2006, 

p. 13) discovered a pygmy rabbit 

population in an old burn area in upper 

Spar Canyon. 

In Montana, Rauscher (1997, p. 14) 

reported that a prescribed burn in 1980 

near Badger Pass, Montana, had been 

recolonized by pygmy rabbits. He did 

not know how long this process had 

taken or if pygmy rabbit densities had 

reached preburn levels. Bockting (2007 

p. 1) found prescribed burns of about 

500 ac (202 ha) have been implemented 

in pygmy rabbit habitat to reduce 

Pseudotsuga menziesii (Douglas fir) 

encroachment. Fire patterns minimized 

burning in the dense sagebrush. A 

mosaic burn pattern was allowed. 

Mechanical treatments (chainsaws) have 

also been used to remove Douglas fir. 

Within one unit, pygmy rabbit burrows 

were identified prior to the burn and 

revisited after the burn. Where the 

sagebrush habitat was not burned over, 

the burrows were still occupied 

(Bockting (2007 p. 1). It appears that 

small burns that create a mosaic do not 

significantly impact pygmy rabbits as 

long as surrounding habitat is 

maintained and the entire population is 

not lost. 

In Nevada, SNWA (2008, pp. 14-15) 

overlaid BLM’s 1980 to 1996 and 1997 

to 2007 wildlife data (BLM 2007b, cited 

in SNWA 2008, p. 14) with Nevada’s 

2000 to 2007 pygmy rabbit occurrence 

data from various sources. They stated 

that review of their map indicates that 

a large portion of Nevada pygmy rabbit 

occurrence data falls in areas with 

relatively low numbers and sizes of 

wildfires, especially in east-central 

Nevada. Large numbers and sizes of 

wildfires have not occurred throughout 

most of the historical and current 

pygmy rabbit range in east-central 

Nevada. They concluded that wildfires 

have not caused major declines in 

pygmy rabbits or their habitat, or pygmy 

rabbit occurrence or geographic range in 

east-central Nevada. 

Summary of Fire Impacts 

Fire has impacted sagebrush 

ecosystems in the past and will 

continue to do so in the future, likely in 

increasing frequency and size of burned 

area. This increase in frequency is likely 

to be attributed to increases in invasive 

plant species cover, especially 

cheatgrass, as discussed above, as well 

as possible impacts of climate change as 

discussed below. Some studies 

summarized above have shown pygmy 

rabbits to have been negatively affected 

in some specific areas within their 

range. However, other studies have 

shown pygmy rabbits are not affected or 

are able to recolonize burned areas. 

Based on reports from site-specific areas 

in Idaho, Montana, California, Nevada, 

and Utah, fire has resulted in some loss 

of sagebrush habitat used by pygmy 

rabbits and has likely resulted in some 

population declines. Of the available 

examples showing loss of habitat, these 

are few in number across the range and 

are not indicative of systematic or 

widespread loss of habitat that may 

have been or is now suitable for pygmy 

rabbits. The scope of loss or 

modification of sagebrush habitat in 

general due to fire does not equally 

relate to loss or modification of pygmy 

rabbit habitat because the pygmy rabbit 

habitat occurs in a patchy distribution 

across the landscape. Some fires have 

resulted in loss of individuals, forage, 

and shelter for pygmy rabbits which 

may have led to an increased 

vulnerability to predation (Gates and 

Eng 1984, cited in Tesky 1994, pp. 8-9). 

Abandonment of home ranges has been 

indicated at some specific sites but with 

the surviving individuals moving to 

adjacent unburned areas (Gates and Eng 

1984 cited in Tesky 1994, p. 9). 

Recolonization or use of burned areas 

has occurred in other site-specific areas. 

It also appears that the adverse impacts 

of fire may be minimized if burns are 

small, reducing possible habitat 

fragmentation and barriers to 

movement; if they occur in a mosaic 

pattern; if surrounding habitat is 

maintained to provide habitat; and if all 

members of a population are not lost. 

Additionally, studies in Montana and 

Idaho have indicated previously burned 

areas used or recolonized by pygmy 

rabbits (Rauscher 1997, Red Willow 

Research Inc. 2000, White and Bartels 

2002, Waterbury 2005, 2006). Also in 

Montana a study indicated that a small 

mosaic fire, leaving some surrounding 

habitat, remained occupied by pygmy 

rabbits (Bockting 2007). Fire effects on 

sagebrush habitats depend on the 

sagebrush species, the composition and 

density of understory species, as well as 

the size, frequency, speed, burn pattern, 

and intensity of the fire. While it is not 

possible to predict the location or extent 

of future fires within pygmy rabbit 

habitat, the numbers of fires are likely 

to increase in the future; however, 

pygmy rabbits have shown an ability to 

survive and recolonize areas after some 

fire events. Based on our review of the 

best available scientific information, we 

conclude habitat loss or modification as 

a result of fire is not a significant threat 

to the pygmy rabbit now or in the 

foreseeable future. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60542 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Pinyon-Juniper Woodlands 

Encroachment 

Pinyon-juniper woodlands have 

increased in the Intermountain West an 

estimated 10 fold since European 

immigrant settlement (Miller and 

Tausch 2001, p. 15) resulting in the loss 

of many sagebrush-bunchgrass 

communities. The major factor cited for 

this increase is the decrease in fire 

return intervals (Miller and Tausch 

2001, p. 25). Other factors attributed to 

this expansion include historical 

livestock grazing patterns, which 

reduced fine fuel buildup that more 

readily carried fire, and possibly climate 

change (Miller and Rose 1999, p. 551; 

Miller and Tausch 2001, p. 15). 

Connelly et al. (2004, pp. 7-8 to 7-12) 

estimated the risk of pinyon-juniper 

displacement of sagebrush within 30 

years for a large portion of the Great 

Basin based on site elevation, proximity 

to extant pinyon-juniper, precipitation, 

and topography. They projected that 60 

percent of the sagebrush in the Great 

Basin was at low risk of being displaced 

by pinyon-juniper, 6 percent was at 

moderate risk, and 35 percent was at 

high risk (Connelly et al. 2004, p. 7-12). 

It appeared that mountain big sagebrush 

was the type most at risk for pinyonjuniper displacement (Connelly et al. 

2004, p. 7-13). They cautioned that 

additional field research is necessary to 

support their projections (Connelly et 

al. 2004, pp. 7-14). 

Surveys (BLM 2006a, pp. 4-5) 

conducted in Oregon found junipers at 

6 of 7 sites surveyed, and pygmy rabbits 

occupied 5 of these sites with an 

additional site being inconclusive in 

terms of occupancy. In areas where 

pygmy rabbit burrows were found close 

to junipers, tree density ranged from 5 

to 15 mature (70 to 120 years old) trees 

per ac (2 to 6 per ha), and trees more 

than 20 years old were common. The 

areas still had a sagebrush and grass 

understory. Burrows were within 50 yd 

(45.7 m) of junipers. . BLM (2007b, pp. 

7-8) mentioned juniper control may 

benefit the pygmy rabbit populations at 

two of the eight occupied sites surveyed 

in Oregon. Juniper control may benefit 

pygmy rabbit populations at these sites 

before canopy closure affects the 

understory (BLM 2006a, p. 4; 2007b, p. 

7). 

Welch (2005, p. 10) indicated 1 of 13 

historical pygmy rabbit sites visited in 

Utah and Idaho were impacted by 

juniper encroachment. Larsen et al. 

(2006, p. 5) found historical pygmy 

rabbit sites in Tooele County, Utah, 

showed evidence of pinyon-juniper 

encroachment, but he did not indicate if 

all four sites had been encroached by 

pinyon-juniper or whether there was 

remaining suitable pygmy rabbit habitat. 

Pinyon-juniper encroachment may 

have a negative impact on pygmy 

rabbits. In Nevada, pinyon-juniper 

woodland populations have increased 

almost 250 percent in distribution 

during the last 150 years (Tausch et al. 

1981, cited in Larrucea and Brussard 

2008b, p. 1640). These conifers slowly 

replace the sagebrush and convert it to 

woodland habitat, eliminating the 

understory (Miller et al. 2000, cited in 

Larrucea and Brussard 2008b, p. 1640). 

Larrucea and Brussard (2008b, p. 

1640) found that a few of these trees at 

a site generally meant that pygmy 

rabbits were not present. Larrucea and 

Brussard (2008b, p. 1639), surveying 

sites in California and Nevada, showed 

that 14 percent of historical pygmy 

rabbit sites showed signs of pinyonjuniper woodland conversion. Of these 

sites, only one had current pygmy rabbit 

activity (Larrucea and Brussard 2008b, 

p. 1639). At 6 of the 14 extirpated 

pinyon-juniper sites, pygmy rabbits 

were known to occur lower in the valley 

where sagebrush habitat existed 

(Larrucea and Brussard 2008b, p. 1640). 

However, based on the information 

available a significant loss or 

modification of habitat and measureable 

population decreases from site 

abandonment or avoidance attributed to 

pinyon-juniper encroachment are not 

occurring across the range. 

Summary of Pinyon-Juniper Woodlands 

Encroachment Impacts 

Based on our review of the best 

available information, we found few 

studies which document negative effects 

of pinyon–juniper expansion on pygmy 

rabbit populations. Based on the studies 

cited above, pinyon-juniper expansion 

has occurred in some occupied pygmy 

rabbit habitat in Oregon, Idaho, 

California, Nevada, and Utah; however, 

pygmy rabbits continued to be present 

at a number of these sites. Larrucea and 

Brussard (2008b, p. 1639), surveyed 

sites in California and Nevada and 

found only 14 percent of historical sites 

showed signs of pinyon-juniper 

woodland conversion, and one had 

current activity. BLM (2006a, p. 4) 

conducted surveys in Oregon and found 

junipers at 6 of 7 sites, and pygmy 

rabbits continued to occupy a majority 

of these sites. Welch (2005, p. 10) found 

only 1 of 13 historical sites in Utah and 

Idaho showed signs of juniper 

encroachment. Larsen et al. (2006, p. 5) 

found four historical sites in Utah may 

have showed pinyon-juniper 

encroachment. The encroachment of 

pinyon-juniper into occupied pygmy 

rabbit habitat is a slow process, and 

pygmy rabbits may be able to inhabit 

those areas or shift their home range to 

adjacent areas if pinyon-junipers habitat 

becomes established at a site. Therefore, 

based on the best available scientific 

and commercial information, we 

conclude that pinyon-juniper expansion 

is not a significant threat to the pygmy 

rabbit now or in the foreseeable future. 

Urban and Rural Development 

Historical destruction of sagebrush 

habitat for urban development has 

occurred (Braun 1998, pp. 6-7) with 

more recent expansion into rural areas 

causing additional loss (Braun 1998, pp. 

6-7). Since 1950, the western United 

States has experienced rapid human 

population growth with regional rates 

higher than the national average (Brown 

et al. 2005 cited in Leu and Hanser in 

press, p. 4). Fifty percent of all 

population growth in the United States 

from 1990 to 2000 occurred in western 

states (Perry and Mackun 2001 cited in 

Anderson and Woosley 2005, p. 6). The 

amount of uninhabited area in the Great 

Basin (Idaho, California, Nevada, and 

Utah) has decreased from 90,000 km2

(34,749 mi2) in 1990 to less than 12,000 

km2 (4.633 mi2) in 2004 (Knick et al. in 

press, p. 20). The petitioner contended 

that power lines, fences, and roads that 

are associated with urban and rural 

development may have also resulted in 

the direct loss of sagebrush habitat and 

subsequently affected pygmy rabbits. 

Urban and rural development has 

impacted and may impact pygmy rabbit 

populations on a local scale. Possible 

effects to pygmy rabbits include loss of 

food and shelter, home range 

abandonment, injury or death at the 

time of vegetation clearing, habitat 

fragmentation, and population declines. 

Power poles and fences can provide 

hunting and roosting perches and 

nesting support, for many raptor species 

that are known to prey upon pygmy 

rabbits. In addition to direct habitat loss, 

roads may disrupt pygmy rabbit 

dispersal movements, and exacerbate 

potential impacts due to habitat 

fragmentation. 

Some research indicates that pygmy 

rabbits can occur where humans are 

present, while other research indicates 

that the human-developed habitat is not 

inhabited by pygmy rabbits. For 

example, Red Willow Research Inc. 

(2000, p 6) observed a pygmy rabbit 

under a conifer near a main ranch house 

in Idaho. In Nevada and California, 

Larrucea and Brussard (2008b, p. 1639) 

found 21 percent of historical sites 

showed signs of urbanization and still 

had pygmy rabbits present. White and 

Bartels (2002, pp. 7-8) found urban 

development had impacted 3 of 13 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60543 

historical pygmy rabbit locations in 

Idaho, and no active pygmy rabbit 

burrows were found. Janson (2002, p. 

32) discovered that one of his 1940’s 

pygmy rabbit study areas was impacted 

by residential and commercial 

development near Cedar City, Utah, 

when it was revisited in 2001. He 

reported that his study area had been 

‘‘taken over’’ by development and no 

pygmy rabbits or recent sign was seen. 

The petitioners contend that power 

lines and fences associated with urban 

and rural development result in loss of 

pygmy rabbit habitat, predation, 

displacement, and creation of 

movement barriers to pygmy rabbit 

populations. The available information 

does not document that power lines or 

fences are causing these impacts to 

pygmy rabbit populations. 

Estes-Zumpf and Rachlow (2009, p. 

367) found that several radio-collared 

pygmy rabbits crossed gravel roads and 

creeks in Idaho. Rauscher (1997, p. 14) 

reported the use of a subnivian (layer 

between snow and soil surface) tunnel 

that extended across a back country 

road near Badger Pass, Montana. 

Western EcoSystems Technology, Inc. 

(2008, p. 28) reported observations of 

pygmy rabbits crossing open areas, 

including desert grasslands with limited 

shrub cover, roads, and between shrub 

lands surrounded by grasslands in 

Wyoming. These few studies indicate 

that roads do not significantly affect 

pygmy rabbit movements. 

Summary of Urban and Rural 

Development Impacts 

Although loss of sagebrush habitat 

due to development has been 

documented and will continue in the 

future, the amount of suitable or 

occupied pygmy rabbit habitat lost (or 

the magnitude of that loss across the 

range) is minimal in scale compared to 

overall sagebrush habitat and will likely 

remain so. Based on the best available 

information, pygmy rabbits have been 

reported to have been impacted by some 

development in a few site-specific areas 

in Idaho and Utah, but they have also 

continued to be present in some other 

areas. The scope of loss or modification 

of sagebrush habitat in general due to 

urban and rural development does not 

equally relate to the loss or modification 

of pygmy rabbit habitat because pygmy 

rabbits are patchily distributed across 

the landscape. 

While power lines, fences, and roads 

associated with development are also 

known to occur across sagebrush habitat 

within the range of the pygmy rabbit, we 

have no information regarding the 

amount of pygmy rabbit habitat that has 

been impacted across the range. The 

best available scientific information 

does not indicate that power lines, 

fences, and roads are threats to the 

pygmy rabbit. We do not have reports of 

raptors associated with power lines or 

fences impacting pygmy rabbit 

populations. The best available 

scientific information indicates that 

pygmy rabbits will cross roads, 

suggesting roads may be less of a barrier 

to pygmy rabbit movements than 

previously thought. Therefore, based on 

the best available scientific and 

commercial information, we conclude 

that urban and rural development, 

including associated power lines, 

fences, and roads, in the sagebrush 

ecosystem are not significant threats to 

the pygmy rabbit now or in the 

foreseeable future. 

Mining 

Sagebrush habitat throughout the west 

has been impacted by gold, coal, and 

uranium mining (Braun 1998, pp. 5-6). 

Mining, livestock grazing, and ranching 

are decreasing as a percent of the 

economics in some parts of the western 

United States (Hansen et al. 2002, 2005 

cited in Knick et al. in press, p. 56). 

Immediate impacts from mining to 

sagebrush habitat include direct loss 

from mining and construction of 

associated facilities, roads, and power 

lines (Braun 1998, pp. 5-6). In western 

North America, development of mines 

and energy resources began before 1900 

(Robbins and Wolf 1994, cited in Braun 

1998, p. 5). 

While comprehensive information on 

the number or surface extent of mines 

across the range of the pygmy rabbit is 

not known, the development of mineral 

resources is occurring on a large-scale 

and important to the economies of a few 

of the states in the range. For example, 

Nevada ranked second in the United 

States in terms of value of overall 

nonfuel mineral production in 2006 

(U.S. Geological Survey 2007, p. 10); 

Wyoming is the largest coal producer in 

the U.S. (Wyoming Mining Association 

2008, p. 2). 

Between 2006 and 2007, surface coal 

production increased by 1.6 percent in 

Wyoming (EIA, http://www.eia.doe.gov/ 

cneaf/coal/page/acr/table1.pdf, 

accessed October 19, 2008). The number 

of Wyoming coal mines increased from 

19 in 2005 to 23 in 2007 (Wyoming 

Mining Association 2005, p 5; 2008, p. 

6). Most of these mines are located in 

the Powder River Basin (Wyoming 

Mining Association 2008, p. 2) which is 

not within the known range of the 

pygmy rabbit in that State. 

Possible impacts from mining to 

pygmy rabbits could include injury or 

death, loss or reduction of forage or 

shelter, temporary or permanent home 

range abandonment, increased habitat 

fragmentation, increased dispersal 

barriers, increased predation, and 

population declines. Red Willow 

Research Inc. (2000, p. 6) reported a 

pygmy rabbit sighting near the 

Historical Tallman Pit on the Sawtooth 

National Forest, Idaho. The individual 

was observed entering the rocks and 

boulders on the east edge of the pit. In 

California, pygmy rabbits have been 

observed in the area around Bodie, a 

mining town that was abandoned in the 

mid 1930’s (Severaid 1950, p. 2). In 

Oregon, two survey areas supported 

active pygmy rabbit burrows at inactive 

diatomaceous earth mines (BLM 2008d, 

pp. 3, 6). One pygmy rabbit was 

observed at one of the sites (BLM 2008d, 

p. 6). Still, the best available scientific 

information does not indicate whether 

pygmy rabbits occupied these areas 

prior to or during the active mining 

period or if the observed individuals 

colonized or recolonized the areas after 

mining activities ceased. 

Summary of Mining Impacts 

Though mining activities occur 

within sagebrush habitat, we do not 

have an estimate of habitat lost to 

mining impacts; however the impact to 

pygmy rabbit habitat is likely small 

compared to the overall range of the 

species and will likely continue to 

remain so in the future. Noted increases 

in the number of Wyoming coal mines 

occurred mostly in the Powder River 

Basin outside the known range of the 

pygmy rabbit in that State. We do have 

some information that indicates pygmy 

rabbits have been observed at specific 

mining areas in Idaho, California, and 

Oregon which may indicate pygmy 

rabbits are adaptable and can exist near 

mining sites or reestablish use of mining 

areas after mining activities have 

ceased. The best available scientific 

information indicates that significant 

loss or modification of habitat and 

measureable population decreases due 

to habitat loss or modification from 

mining impacts are not occurring across 

the range. Therefore, based on the best 

available scientific and commercial 

information, we conclude that habitat 

loss or modification due to mining is 

not a significant threat to the pygmy 

rabbit now or in the foreseeable future. 

Energy Exploration and Development 

Energy exploration and development 

of non-renewable resources (oil, gas, 

coal) has occurred in sagebrush habitat 

since the late 1800’s (Connelly et al. 

2004, p. 7-38). Energy development and 

its associated facilities (well pads, 

access roads, pipelines, compressor 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60544 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

stations, pumping stations, and power 

lines) can impact sagebrush habitats. 

The exploration and development of 

fossil fuels in sagebrush habitats has 

increased recently as prices and demand 

are spurred by geopolitical uncertainties 

and legislative mandates (National 

Petroleum Council 2007, pp. 5-7). 

Legislative mandates include those of 

the Energy Policy and Conservation Act 

of 1975 (EPCA), 42 U.S.C. 6201, et seq., 

to secure energy supplies and increase 

the availability of fossil fuels. The EPCA 

was re-authorized and amended by the 

Energy Policy Act of 2000, P.L. 106-469, 

and the Energy Policy Act of 2005, PL 

109-58, mandating inventory of Federal 

nonrenewable resources, economic 

incentives for energy development, 

identification of impediments to timely 

granting of leases and post-leasing 

development, and increased 

development of renewable energy 

resources (DOE 2005). In addition, the 

Energy Policy Act of 2005 mandated 

designation of federal lands for energy 

transport corridors (DOE 2005). 

Present and future exploration and 

development is highly likely to focus on 

areas of highest potential return. 

Pursuant to the EPCA mandates, the 

BLM as lead Federal agency for EPCA 

implementation, released results in 

2003 of the first of a 4-phase survey 

intended to identify onshore oil and gas 

resources. Phases II and III were 

published in 2006 and 2008, 

respectively. Phase III supersedes the 

previous phases (DOI et al. 2008, p. 6). 

Available EPCA inventories indicate 

energy resources (oil and gas) in 11 

geological basins within the range of the 

greater sage-grouse as identified in the 

2006 Conservation Strategy (Stiver et al. 

2006, p. 1-11) for the greater sage 

grouse. Some of these basins also 

correspond with pygmy rabbit range: the 

Wyoming Thrust Belt of Wyoming, Utah 

and Idaho; Southwestern Wyoming 

Basin including portions of Wyoming 

and Utah; and Eastern Great Basin in 

Nevada, Utah, and Southern Idaho. 

We are aware that many land parcels 

within the range of the pygmy rabbit are 

leased for oil and gas development. Oil 

fields have been developed in eastcentral Nevada and western and central 

Utah. Major oil and gas production areas 

occur in eastern Utah, southwest 

Wyoming, and central California (USFS 

2008a, p. 25). We are aware of a number 

of projects related to oil, gas, and 

coalbed methane production in 

sagebrush habitats—-most notably in 

Wyoming—-as can be seen from the 

following list of NEPA documents: 

• Final Environmental Impact Statement 

(EIS) for the Jack Morrow Hills 

Coordinated Activity Plan/Proposed 

Green River Resource Management 

Plan Amendment, (BLM 2004a), for 

Sweetwater, Fremont and Sublette 

Counties, Wyoming; 

• Scoping Notice for South Piney 

Natural Gas Development Project, 

(BLM undated), for Sublette 

County, Wyoming; 

• Final Supplemental EIS for the 

Pinedale Anticline Oil and Gas 

Exploration and Development 

Project, (BLM 2008a), for Sublette 

County, Wyoming; 

• Record of Decision Jonah Infill Drilling 

Project, (BLM 2006b), for Sublette 

County, Wyoming; 

• Record of Decision EIS for the Atlantic 

Rim Natural Gas Field Development 

Project, (BLM 2007d), for Carbon 

County, Wyoming; 

• Finding of No Significant Impact and 

Decision Record for the Bitter Creek 

Shallow Oil and Gas Project, 

Sweetwater County, Wyoming 

(BLM 2005b); 

• Decision Record, Finding of No 

significant Impact and 

Environmental Assessment for the 

Copper Ridge Shallow Gas 

Exploration and Development 

Project, (BLM 2003b), for 

Sweetwater County, Wyoming; 

• Environmental Assessment, Finding of 

No significant Impact and Decision 

Record for the Pacific Rim Shallow 

Gas Exploration and Development 

Project, Sweetwater County, 

Wyoming (BLM 2004b); 

• Record of Decision for White Pine and 

Grant-Quinn Oil and Gas Leasing 

Project, (USFS 2007), for White 

Pine, Nye, and Lincoln Counties, 

Nevada; 

• Final EIS Greater Deadman Bench Oil 

and Gas Producing Region, (BLM 

2008b), for Uintah County, Utah. 

Currently, pygmy rabbits could be 

most affected by an energy resources 

development concentration in the 

Southwest Wyoming Basin. For 

example, the BLM published the Record 

of Decision in 2008 for Pinedale 

Anticline Project Area in southwest 

Wyoming (BLM 2008e). The project 

description included up to 900 drill 

pads, including dry holes, over a 10 to 

15–year development period (BLM 

2008a, p. 4-4). Approximately 250 new 

well pads are proposed in addition to 

pipelines and other facilities (BLM 

2008e, p. 36). Total initial direct 

disturbance acres for the entire Pinedale 

project are approximately 25,800 ac 

(10,400 ha) with over 18,000 ac (7,200 

ha) in sagebrush land cover type (BLM 

2008a, pp. 4-52). 

The Jonah Gas Project also occurs in 

the Pinedale Anticline area of the 

Southwest Wyoming Basin. In 2006, the 

BLM issued a Record of Decision (BLM 

2006b, entire) and a final EIS (BLM 

2006c, entire) to extend the existing 

project to an additional 3,100 wells and 

up to 16,200 ac (6,556 ha) of new 

surface disturbance (BLM 2006c, p. 2-4). 

Specific features include: at least 64 

well pads per 640 ac (259 km2), up to 

473 mi (761 km) of pipeline and roads, 

and 140 ac (56 ha) of new surface 

disturbance for ancillary facilities (BLM 

2006c, pp. 2-4 to 2-5). 

The Pinedale Anticline and Jonah Gas 

Field Projects as analyzed by the BLM’s 

EISs are not the only oil and gas 

development occurring in Wyoming. 

According to the Wyoming Oil and Gas 

Commission completed wells in 

Wyoming counties with sagebrush 

habitats increased from a total of 37,144 

in 2005 to 42,510 in 2007. An additional 

6,209 applications for permit to drill 

were approved from January through 

September 2008 in these counties 

(WOGC 2008, http://wogcc.state.wy.us, 

accessed September 29, 2008). 

The Ruby Pipeline Project, as 

proposed, involves the construction and 

operation of a 675-mi-(1,086-km)-42- 

inch (106.7-cm)-diameter natural gas 

pipeline. The pipeline would transport 

natural gas from western Wyoming, 

through northern Utah and Nevada, to 

south central Oregon (Federal Energy 

Regulatory Commission (FERC) 2010, 

pp. 1-2- 1-3). The project would cross 

known occupied pygmy rabbit habitat in 

Wyoming, Utah, and Nevada (FERC 

2010, p. 4-126). Approximately 62 ac 

(25 ha) of suitable pygmy rabbit habitat 

was delineated along the pipeline route 

in these three states (FERC 2010, p. 4- 

147). The Applicant has committed to 

minimize impacts to pygmy rabbits by 

conducting preconstruction surveys, 

realignment of portions of the pipeline 

to avoid occupied habitat, construction 

buffers, construction timing restrictions, 

and specific re-vegetation activities, 

among other commitments (FERC 2010, 

pp. 4-132; 4-159; 5-9). 

Possible impacts to pygmy rabbits due 

to nonrenewable energy exploration and 

development include injury or death, 

loss of habitat, habitat fragmentation, 

dispersal barriers, noise, and 

disturbance due to increased human 

presence. Lance (2008, pp. 5-6) 

provided information on oil and gas 

development in southwestern Wyoming 

as it relates to pygmy rabbits. He 

indicated that the greatest number of 

wells drilled to date has occurred in the 

Pinedale/Jonah fields in southern 

Sublette County (Big Piney area south to 

Granger; in the Overthrust Belt along the 

Wyoming/Utah border; the Wamsutter 

area). While oil and gas development 

has been intensive in some portions of 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60545 

the pygmy rabbit’s predicted range in 

Wyoming, the majority of the range has 

been subjected to scattered oil and gas 

exploration and/or development, or no 

exploration or development at all. The 

pygmy rabbit’s predicted range in 

Wyoming is based on a predictive 

distribution model that uses habitat 

variables and confirmed pygmy rabbit 

records (sightings) from the Wyoming 

Natural Diversity database (Lance 2008, 

pp. 2-3). Lance (2008, p. 5) estimated 

that 9,200 oil and gas wells have been 

drilled within the predicted range. 

Based on an average disturbance of 25 

ac (10.1 ha) per well (accounting for 

pad, production facility, roads, 

pipelines, etc.), it was estimated that 4 

percent of the predicted range in 

Wyoming has been disturbed by 

conventional oil and gas development. 

Coal bed methane development is 

expected in isolated portions of the 

pygmy rabbit’s predicted range in 

Wyoming. The areas potentially suitable 

for coal bed methane development 

include the area around Atlantic Rim 

and Baggs in Carbon County, and in the 

vicinity of Hay Reservoir in Sweetwater 

County. 

While some power lines may cross 

habitat occupied by pygmy rabbits, 

localized and insignificant impacts are 

expected given the linear nature of these 

projects (Lance 2008, p. 6). Power poles 

could be used as perches by avian 

predators preying on pygmy rabbits; 

however, as discussed above, we were 

not able to find evidence documenting 

this. 

Purcell (2006, pp. 2, 34) expressed 

concern for loss of sagebrush 

communities at energy production sites 

in Wyoming. Purcell (2006, p. 110) 

mentioned that oil and gas development 

in southwestern and south central 

portions of Wyoming may contribute to 

degradation of suitable areas used by 

pygmy rabbits due to destruction of 

sagebrush and sodium contamination of 

the soil; and recommended that research 

be conducted to determine pygmy rabbit 

response to these disturbances. 

In contrast, two studies indicate 

energy projects and pygmy rabbits can 

co-exist. Hayden-Wing Associates, Inc. 

(2008b, p. 2) compiled pygmy rabbit 

observations of all sign (visuals, 

burrows and pellets, burrows only, 

pellets only) they collected during 1994 

to 2007 surveys in Wyoming. All of 

their observations were within 109 yd 

(100 m) of roads (Hayden-Wing 

Associates, Inc. 2008b, p. 3). 

Observations were recorded in the 

Continental Divide-Wamsutter and 

Creston-Blue Gap natural gas project 

areas in Carbon and Sweetwater 

Counties; Moxa Arch natural gas 

development area in Lincoln, Uinta, and 

Sweetwater Counties; Jonah gas field in 

Sublette County; and Lake Ridge 3D 

seismic area in Lincoln County 

(Hayden-Wing Associates, Inc. 2008b, p. 

2). They recorded 1,151 pygmy rabbit 

observations (visuals, n=216; burrows 

and pellets, n=422, pellets only, n=513) 

(Hayden-Wing Associates, Inc. (2008b, 

p. 3). The majority of observations (50 

percent) occurred in Moxa, 26 percent 

occurred within the Continental DivideWamsutter and Creston-Blue Gap areas, 

17 percent in the Jonah gas field, and 

6.5 percent in the Lake Ridge 3D seismic 

area (Hayden-Wing Associates, Inc. 

2008b, p. 3). They acknowledge biases 

with road-based surveys and possible 

uncertainties in assigning pellets to 

pygmy rabbits, but concluded that 

energy development and pygmy rabbits 

do coexist throughout portions of 

Wyoming (Hayden-Wing Associates, 

Inc. 2008b, p. 3). Pygmy rabbit locations 

were farther away from well pads, but 

the analysis, in general, suggests that 

pygmy rabbits are capable of tolerating 

some level of disturbance (Hayden-Wing 

Associates, Inc. 2008b, p. 4). The 

authors suggest that research needs to be 

conducted to quantify the mechanisms 

that affect pygmy rabbits due to energy 

development, to understand thresholds 

at which negative impacts occur, and to 

determine ways the industry can avoid 

impacting populations (Hayden-Wing 

Associates, Inc. 2008b, p. 4). 

Estes-Zumpf et al. (2009, p. 4) began 

a pygmy rabbit monitoring program in 

the Pinedale Anticline Project Area 

(PAPA) (359 plots) and in a neighboring 

Boulder reference area (85 plots), 

Sublette County, Wyoming, in 2009. 

Surveys confirmed recent or current 

pygmy rabbit use at 83 percent of the 

plots, and there were 120 confirmed 

pygmy rabbit sightings across both 

study areas (Estes-Zumpf et al. 2009, p. 

9). The Boulder reference area contained 

a greater proportion of active plots (81 

percent) compared to the PAPA (54 

percent) (Estes-Zumpf et al. 2009, p. 9). 

One hundred and twelve plots were 

surveyed in the PAPA that occurred 

within the five oil and gas development 

areas (Estes-Zumpf et al. 2009, p. 10). 

The proportion of active (52 percent) 

and recently active (25 percent) plots 

within the development zone was 

similar to the proportion of active (54 

percent) and recently active (26 percent) 

plots throughout the PAPA (EstesZumpf et al. 2009, p. 10). Thirty-two 

known plots were surveyed inside the 

development zone and 19 known plots 

were surveyed in the remainder of the 

PAPA; the proportion of known plots in 

the development zone that were still 

active (88 percent) was similar to the 

proportion of known plots still active 

(74 percent) in the remainder of the 

PAPA (Estes-Zumpf et al. 2009, p. 10). 

Only 2 (6 percent) of previously known 

active plots within the development 

zone showed recent, but not current, 

pygmy rabbit activity (Estes-Zumpf et 

al. 2009, p. 10). 

Past and present renewable energy 

development (wind, solar, and 

geothermal) in sagebrush habitats could 

impact pygmy rabbits. Possible impacts 

to pygmy rabbits could include injury or 

death, loss of habitat, habitat 

fragmentation, dispersal barriers, noise, 

and disturbance due to increased 

human presence. The Department of 

Interior (DOI) and Department of Energy 

(DOE) (2003, pp. 2-17) assessed the 

potential for renewable energy being 

developed on public lands in 11 

western States. This assessment also 

indicated which BLM planning areas 

within these States offered the highest 

potential for each type of renewable 

energy (DOI and DOE 2003, pp. 18-24). 

BLM published a Final Programmatic 

EIS on Wind Energy Development on 

BLM-administered Lands in the Western 

United States (BLM 2005c, entire). This 

EIS addresses the environmental, social, 

and economic impacts associated with 

wind energy development on BLMadministered lands in 11 western States 

under the direction of increasing 

renewable energy production on public 

lands while minimizing environmental 

and socio-cultural impacts (BLM 2005c, 

p. ES-1). Future proposed wind energy 

projects may impact sagebrush habitats, 

and therefore, pygmy rabbits within the 

seven States. The 12–month finding for 

the greater sage-grouse (75 FR 13950) 

provides acreage of sagebrush habitat 

with wind energy development 

potential by Greater Sage-grouse 

Management Zone. Selecting those 

management zones that most 

appropriately overlap with the pygmy 

rabbit range, the estimated percent of 

sagebrush with developable wind 

potential in the species range is 3 to 9 

percent (Greater Sage-grouse 

Management Zones III, IV, V). Greater 

Sage-grouse Management Zone II has 42 

percent of sagebrush habitat with 

developable wind potential, but this 

incorporates a much larger area of 

Wyoming than is known to be occupied 

by pygmy rabbits. 

Wind development could occur in the 

future in the eastern portion of the 

predicted range in Wyoming; most 

projects are expected to be located east 

of Rawlins, and some may occur 

between Rawlins and Wamsutter in 

pygmy rabbit habitat with localized 

impacts (Lance 2008, p. 6). 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60546 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Eastern Nevada and the Pinedale area 

of Wyoming are the areas within the 

pygmy rabbit range with good potential 

for commercial solar development (EIA 

2009e, entire cited in 75 FR 13953). The 

BLM is developing a programmatic EIS 

for leasing and development of solar 

energy on BLM lands (75 FR 13953). 

Geothermal energy facilities occur in 

pygmy rabbit range in California, 

Nevada, Utah, and Idaho. Geothermal 

potential occurs across pygmy rabbit 

range in the four mentioned states above 

as well as in southeast Oregon and west 

central Wyoming (EIA 2009e, entire 

cited in 75 FR 13953). 

A Programmatic EIS for the 

Designation of Energy Corridors on 

Federal Land in the 11 Western States 

(DOE 2008) was published in 2008. This 

EIS addresses section 368 of the Energy 

Policy Act of 2005 which directs the 

designation of corridors for oil, gas, and 

hydrogen pipelines, and electricity 

transmission and distribution facilities 

on Federal lands. Federal agencies are 

required to conduct environmental 

reviews to complete the designation and 

incorporate the designated corridors 

into agency land use and resource 

management plans or equivalent plans. 

This EIS proposes only designation of 

corridors, and no environmental 

impacts are attributed to this action. 

Section 368 does not require agencies to 

consider or approve specific projects, 

applications for rights-of-way (ROW), or 

other permits within any designated 

corridor nor does section 368 direct, 

license, or permit any activity on the 

ground. Any interested applicant would 

need to apply for a ROW authorization 

and the agency would consider each 

application under the requirements of 

various laws and related regulations 

(DOE 2008, S-1-S-2). The proposed 

action would designate more than 6,000 

mi (9,600 km) with an average width of 

3,500 ft (1 km) of energy corridors 

across the West (DOE 2008, p. S-17). 

Federal land not presently in 

transportation or utility right-of-way is 

proposed for use in Idaho (102 mi or 

164 km), Montana (149 mi or 240 km), 

Nevada (373 mi or 600 km), Oregon (253 

mi or 407 km), Utah (166 mi or 268 km), 

Wyoming (70 mi or 113 km), and 

California (unclear as miles in existing 

right-of-way is greater than miles of 

proposed corridors) (DOE 2008, p. S-18). 

Although we do not have data on how 

much of the corridor is in sagebrush 

habitat within the range of pygmy 

rabbits, based on the proposed location, 

habitat in Wyoming, Idaho, Utah, 

Nevada, and Oregon would be most 

affected. 

Summary of Energy Exploration and 

Development Impacts 

Energy (nonrenewable and renewable) 

exploration and development has been 

documented within sagebrush habitat. 

Pygmy rabbits have been reported to 

occur in areas impacted by energy 

development in Wyoming and have 

continued to be present in these areas 

but with unknown impacts to 

population trends and long-term 

population persistence. The scope of 

loss or modification of sagebrush habitat 

in general due to energy exploration and 

development does not equally relate to 

the loss or modification of pygmy rabbit 

habitat because of the pygmy rabbit’s 

patchy habitat distribution across the 

landscape. Available information 

indicates that significant loss or 

modification of habitat and measureable 

population declines from injuries or 

mortalities, temporary home range 

abandonment or permanent home range 

shift to adjacent areas, increased habitat 

fragmentation, increased dispersal 

barriers, noise, or increased human 

presence due to energy development 

(nonrenewable and renewable) are not 

occurring across the range. 

Energy exploration and development 

is occurring, especially within a portion 

of the pygmy rabbit’s range in Wyoming. 

Yet, the available information does not 

indicate that this potential threat is 

negatively impacting pygmy rabbits. 

Therefore, based on the best available 

scientific and commercial information, 

we conclude that habitat degradation 

and loss due to energy exploration and 

development is not a significant threat 

to the pygmy rabbit now or in the 

foreseeable future. 

Habitat Fragmentation 

Habitat fragmentation is the 

separating of previously contiguous, 

functional habitat components that are 

used by a particular species. Habitat 

fragmentation can result from direct 

losses that leave remaining habitat in 

discontinuous patches or from alteration 

of habitat such that the habitat becomes 

unusable to the species (i.e., functional 

habitat loss). This type of loss can result 

from disturbances that change a 

habitat’s successional state or remove 

one or more of its habitat functions; 

barriers that prevent use of suitable 

areas; and activities that prevent use of 

habitat due to behavioral avoidance. 

Most extant sagebrush habitat has been 

altered since European immigrant 

settlement of the West (Braun 1998, p. 

2; West and Young 2000, Miller and 

Eddleman 2001, cited in Knick et al. 

2003, p. 614; Connelly et al. 2004, p. 7- 

1). Sagebrush habitat continues to be 

fragmented (Knick et al. 2003, p. 625) 

through various factors (natural and 

anthropogenic) and will into the future. 

Cumulative effects of habitat 

fragmentation have not been quantified 

over the range of sagebrush and most 

fragmentation cannot be attributed to 

specific land uses (Knick et al. 2003, pp. 

614-616). Review of the humanfootprint intensity within the greater 

sage-grouse management zones showed 

that the Northern and Southern Great 

Basin and Snake River Plain sage-grouse 

management zones contained a greater 

proportion of low-intensity human 

footprint area compared to the rangewide intensity (Leu and Hanser in press, 

p. 14). Sage-grouse management zones 

with a higher proportion of highintensity human footprint area 

(Colorado Plateau, Great Plains, and 

Columbia Basin) compared to the rangewide intensity (Leu and Hanser in press, 

p. 14) occurred outside of the range 

occupied by the pygmy rabbit. Thus, in 

sage-grouse management zones, the 

range of the pygmy rabbit occurs mostly 

within a low-intensity human footprint 

area. 

In general, habitat fragmentation has 

been mentioned as a potential threat to 

pygmy rabbits by several researchers 

(White and Bartels 2002, p. 13; Bartels 

2003, p. 99; Roberts 2003a, p. 9). 

Potential impacts to pygmy rabbits 

include loss of habitat, increased 

dispersal distance, increased predation, 

and increased isolation. Weiss and Verts 

(1984, p. 570), in Oregon, stated that 

fragmentation of sagebrush posed a 

threat to pygmy rabbit populations by 

reducing the size of this vegetative 

community and increasing the distances 

between suitable areas; however, the 

severity of this threat to pygmy rabbits 

cannot be adequately assessed without 

improved understanding of the 

dispersal abilities of this species and 

minimum sagebrush patch size 

requirements. Katzner and Parker (1997, 

p. 1071) stated that fragmentation of 

habitat can influence size, stability, and 

success of pygmy rabbit populations 

because of their low dispersal 

capabilities. However, subsequent 

studies by researchers, as indicated 

below, demonstrate dispersal 

capabilities of pygmy rabbits are greater 

than initially thought and that potential 

barriers such as perennial creeks and 

roads do not appear to be barriers to 

gene flow among some populations. 

Pygmy rabbits depend on sagebrush, 

but there is no information available to 

indicate minimum sagebrush patch size 

required to support populations. In 

Washington, the Service (2007, p. 54) 

estimated that a subpopulation of at 

least 500 Columbia Basin DPS pygmy 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60547 

rabbits would need an area of between 

454 and 3,250 ac (184 and 1,316 ha) of 

suitable habitat. Some studies indicate 

that pygmy rabbit populations may not 

be as isolated as previously thought. 

This has implications for recolonization 

and genetic exchange between nearby 

areas. In Montana, movement data has 

shown pygmy rabbits will cross 

relatively small open areas (1,500 ft (457 

m)) to reach suitable habitat (Rauscher 

1997, p. 5). In Wyoming, Katzner and 

Parker (1998, p. 73) reported a pygmy 

rabbit traveled long-distance (2.2 mi (3.5 

km)) through open habitat likely 

unsuitable for long-term habitation. In 

Idaho, Estes-Zumpf and Rachlow (2009, 

p. 367) found median dispersal 

movements of 0.93 mi (1.5 km) and 3.9 

mi (6.2 km) and maximum dispersal 

movements of 4.0 mi (6.5 km) and 7.4 

mi (11.9 km) by male and female 

juvenile pygmy rabbits, respectively. 

Crawford (2008, p. 54) in Nevada and 

Oregon reported that 24 radio-marked 

rabbits moved greater than 0.3 mi (0.5 

km) with a maximum long-distance 

movement of 5.3 mi (8.5 km) recorded 

by a juvenile female. 

Continued survey efforts in recent 

years have found new populations 

throughout the pygmy rabbit’s range. 

Rachlow and Witham (2006, p. 6) found 

that the locations of the 32 new sites in 

the Camas Prairie of south central Idaho 

indicated the possibility that movement 

can occur among several of these sites. 

The sites are separated by distances of 

less than 3.1 to 4.3 mi (5 to 7 km) which 

are within dispersal capabilities shown 

by Estes-Zumpf and Rachlow (2009) and 

Rachlow and Witham (2006, p. 6). 

Because most surveys for pygmy rabbits 

are limited to a single state, it is 

noteworthy that some reports mention 

occupied sites near state lines. This 

suggests the possibility that additional 

unreported genetic exchange may be 

occurring where ranges overlap two 

states. This would further reduce the 

concern of habitat fragmentation and 

isolation. Roberts (2003a, p. 9) reported 

that 6 of the 9 active burrow systems 

found were within 15 mi (24.1 km) of 

the Idaho State line. One was within 3 

mi (4.8 km) of the Montana border at the 

head of Medicine Lodge Creek, Clark 

County. Two active burrow sites were 

within 8 mi (12.9 km) of both Wyoming 

and Utah borders on Pegram Creek, Bear 

Lake County. One active burrow site 

found on the Curlew National 

Grasslands was about 15 mi (24.1 km) 

north of the Utah border and two active 

burrows sites were about 15 mi (24.1 

km) north of the Nevada border near 

Riddle, Idaho. In Montana, Hendricks et 

al. (2007, p. 13) mentioned that two new 

active sites found during their survey 

occurred in gaps between other 

locations and suggested pygmy rabbits 

may exist in additional locations in Big 

Hole Valley. Continued occupancy of 

previously known locations along the 

east side of Big Hole Valley may benefit 

through connectivity with populations 

in Grasshopper Valley, Argenta Flats, 

and Horse Prairie located to the south. 

Estes-Zumpf et al. (2010, p. 212) 

obtained genotypes for 249 pygmy 

rabbits from 8 sample locations in 

Lemhi Valley (5) and Camas Prairie (3), 

Idaho. They did not document strong 

evidence of genetic substructure based 

on nuclear microsatellites among pygmy 

rabbit populations within the study 

areas (Estes-Zumpf et al. 2010, p. 215). 

Lack of strong population structure 

within the study areas indicates that 

perennial creeks and roads do not 

appear to create substantial barriers to 

gene flow (Estes-Zumpf et al. 2010, pp. 

215-216). Levels of genetic diversity in 

pygmy rabbits were relatively high in 

the study areas (Estes-Zumpf et al. 2010, 

pp. 214). Sample locations within 8.1 

mi (13 km) of one another in each study 

area showed sufficient gene flow to 

constitute single populations (EstesZumpf et al. 2010, pp. 215). 

In Utah, Flinders (2007, pp. 2-3) 

found fairly extensive populations in 

Hamlin Valley located on the Utah/ 

Nevada border in Iron and Beaver 

Counties (Utah). He thought that this 

area may provide an important habitat 

corridor between the two States as he 

found pygmy rabbit use for several 

miles on both sides of the border. 

Summary of Habitat Fragmentation 

Impacts 

Although we cannot estimate the 

amount of suitable or occupied pygmy 

rabbit habitat lost or the magnitude or 

extent of that loss due to habitat 

fragmentation, the habitat used by 

pygmy rabbits is naturally fragmented 

and populations occur in a patchy 

distribution across their range. Because 

of this patchy habitat distribution across 

the range, the scope of loss or 

modification of sagebrush habitat in 

general due to fragmentation does not 

equally relate to the loss or modification 

of pygmy rabbit habitat. Naturally 

fragmented sagebrush habitat occupied 

by pygmy rabbits may not have been 

more prevalent or more contiguous prior 

to human settlement. Local distribution 

of this habitat and the distribution of the 

pygmy rabbit likely shifts over time due 

to disturbances from factors such as fire, 

agriculture production, flooding, 

grazing, and weather patterns. 

Pygmy rabbit populations may be less 

isolated than previously thought based 

on studies in Idaho, Montana, 

Wyoming, Nevada, and Utah. For 

example, studies related to movement 

data indicate pygmy rabbits, including 

juveniles, can move greater distances 

than initially thought (Green and 

Flinders 1979, p. 88; Gahr 1993, p. 108; 

Katzner and Parker 1998, p. 73; 

Crawford 2008, p. 54; Estes-Zumpf and 

Rachlow 2009, p. 367). 

Other studies by Rachlow and 

Witham (2006, p. 6) and Roberts (2003a, 

p. 9) in Idaho, Hendricks et al. (2007, p. 

13) in Montana, and Flinders (2007, pp. 

2-3) in Utah, as detailed above, suggest 

connectivity may occur among several 

areas and between states. Understanding 

dispersal capabilities of pygmy rabbits 

plays an important role in addressing 

the possibility for genetic exchange 

among occupied sites as well as 

determining whether the characteristics 

of a metapopulation apply to this 

species. 

The best available scientific 

information does not indicate that 

fragmented sagebrush habitat is 

negatively impacting pygmy rabbit 

populations across their range. 

Available information indicates through 

genetic analysis that current habitat 

sagebrush distribution does not appear 

to affect dispersal distances, predation, 

or isolation among pygmy rabbit 

populations. Although the necessary 

patch size to support pygmy rabbit 

populations has not been determined, 

this species has been reported to 

historically survive in a naturally 

fragmented habitat. Survey efforts 

demonstrate that pygmy rabbits have 

been found in areas impacted or 

fragmented by various potential threats 

as discussed in Factor A and continue 

to exist in or adjacent to many of these 

areas suggesting that habitat 

fragmentation is not a significant threat 

to this species. While its habitat may be 

impacted to some degree by current 

habitat fragmentation, based on the best 

available scientific and commercial 

information, we conclude that habitat 

fragmentation is not a significant threat 

to the pygmy rabbit now or in the 

foreseeable future. 

Habitat Manipulation Conducted to 

Benefit Greater Sage-Grouse 

There has been a recent and 

widespread interest in the protection 

and restoration of sagebrush habitats 

with an emphasis on greater sage-grouse 

conservation (BLM 2004c). It is 

uncertain whether efforts implemented 

to improve greater sage-grouse habitat 

will benefit pygmy rabbits. Some habitat 

manipulation to benefit greater sagegrouse could benefit pygmy rabbit (e.g., 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60548 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

pinyon-juniper removal) (Larrucea 2007, 

p. 127). 

Connelly et al. (2000, pp. 977, 980) 

recommend managing sagebrush canopy 

cover for greater sage-grouse habitat at 

10 to 25 percent for brood-rearing, 15 to 

25 percent for breeding habitat, and 10 

to 30 percent for winter habitat. Pygmy 

rabbits, in general, prefer taller, denser 

sagebrush cover relative to the 

surrounding landscape (Green and 

Flinders 1980b, p. 138; Weiss and Verts 

1984, p. 567), which can be greater than 

the 10 to 30 percent range suggested for 

greater sage-grouse habitat needs during 

their various life history stages. Burak 

(2006, pp. 63-64) found total shrub 

cover values ranged from 41 to 67 

percent and sagebrush cover values 

ranged from 12 to 60 percent in areas 

occupied by pygmy rabbits. Reducing 

dense sagebrush cover to benefit greater 

sage-grouse may be in conflict with 

habitat needs of pygmy rabbits. 

In Nevada, Larrucea (2006, p. 7) 

raised a concern that sagebrush 

management plans which target areas of 

mature sagebrush for treatment to 

promote succession (e.g., Greater SageGrouse Conservation Plan for Nevada 

and Eastern California (NDOW 2004), 

cited in Larrucea 2006, p. 7) do not 

protect pygmy rabbit habitat. The goal of 

these plans is to create a mosaic of 

sagebrush stands of differing ages. These 

plans allow for mature sagebrush at the 

end of the succession, but pygmy rabbits 

use their burrows over many seasons 

and require stable, long lasting, mature 

sagebrush. Larrucea (2006, p. 7) 

suggested a modification of these plans 

which would allow protection of habitat 

for pygmy rabbits and recommends 

either: 1) surveying for areas to be 

managed for pygmy rabbit habitat; or 2) 

specifying areas of mature, clumped, 

larger than average sagebrush stands 

within the area to be managed and 

taking a portion of these areas to be 

mapped and managed as stable, mature 

sagebrush sites with no treatments 

applied. The combination of these two 

actions (successional and stable) would 

create a mosaic of ages. This would 

incorporate both the succession desired 

by other plans while protecting the 

stable type of habitat needed by pygmy 

rabbits. The stable, mature sagebrush 

would be available for colonization and 

the earlier successional stages would be 

available for pygmy rabbit dispersal. 

These untreated areas of latesuccessional sagebrush should be 

included in the actively managed 

rotational-successional plan (i.e., 

NDOW 2004). Larrucea (2006) does not 

provide details of any specific project 

implemented within sagebrush habitats 

to improve greater sage-grouse habitat 

and its possible impact to pygmy rabbits 

or their populations. 

Summary of Habitat Manipulation 

Conducted to Benefit Greater SageGrouse 

Sagebrush habitat manipulations to 

benefit greater sage-grouse have 

occurred within the range of the pygmy 

rabbit. Habitat manipulation to benefit 

greater sage-grouse or other species was 

raised as a concern by the petitioners 

and a researcher, but the available 

information does not provide an 

example of the effects of this activity on 

pygmy rabbits. Additionally, the 

available information does not indicate 

there has been a systematic or 

widespread loss of habitat due to habitat 

manipulation that may have been or is 

suitable habitat for pygmy rabbits. 

Because of the pygmy rabbit’s patchy 

habitat distribution across the 

landscape, the scope of loss or 

modification of sagebrush habitat in 

general due to habitat manipulation for 

greater sage-grouse does not equally 

relate to the loss or modification of 

pygmy rabbit habitat. 

Large-scale sagebrush manipulations 

to benefit greater sage-grouse may 

benefit pygmy rabbit. Based on the 

similarities with sagebrush treatments 

discussed earlier, the size and design of 

the manipulated area may minimize 

adverse impacts to pygmy rabbits. If 

designed appropriately, these projects 

may be beneficial to pygmy rabbits by 

opening up areas for new vegetation 

growth or to provide dispersal areas. 

Pygmy rabbits have been found in 

mosaics where large areas of sagebrush 

were left intact and remained connected 

to adjacent sagebrush or where treated 

areas were small and travel distances 

between them were minimal. Therefore, 

based on the best available scientific 

and commercial information, we 

conclude that habitat degradation and 

loss due to habitat manipulations for 

other species is not a significant threat 

to the pygmy rabbit now or in the 

foreseeable future. 

Conservation Strategies and Actions 

All seven States mention the pygmy 

rabbit in their Comprehensive Wildlife 

Conservation Strategies. These strategies 

confer no regulatory mechanisms, but 

indicate that the species or its habitat 

deserves special management 

considerations (Oregon Department of 

Fish and Wildlife 2006; Idaho 

Department of Fish and Game 2005; 

Montana Fish, Wildlife & Parks 2005; 

Wyoming Game and Fish Department 

2005; California Department of Fish and 

Game 2005; Nevada Department of 

Wildlife 2006; Utah Division of Wildlife 

Resources 2006). 

We are not aware of any States 

implementing conservation actions 

specifically for the pygmy rabbit, though 

we are aware of initiatives to restore the 

sagebrush ecosystem within the range of 

the pygmy rabbit. For example, the State 

of Utah Division of Wildlife Resources 

launched the Watershed Initiative in 

2003 to implement restoration projects 

designed to prevent and reverse habitat 

loss. Emphasis has been placed on 

restoration and protection of shrubsteppe and riparian habitats in Utah due 

to their importance to a diversity of 

wildlife species. Completed, current, 

and proposed projects within the range 

of pygmy rabbit total 35,335 ac (14,300 

ha). Monitoring is an important 

component to assessing these treatments 

(Karpowitz 2008, p. 3). In addition, 

research is being conducted to address 

impacts of treatments for greater sagegrouse, mule deer, and pronghorn on 

pygmy rabbit populations. Preliminary 

results indicate that at least a 131.2 ft 

(40-m) buffer should be established 

between active pygmy rabbit burrows 

and treatments. Future designs should 

also implement a mosaic pattern and 

preserve long and wide swaths of 

undisturbed mature big sagebrush with 

corridors of connectivity between all 

residual stands. All current and future 

habitat projects in pygmy rabbit habitat 

follow these recommendations 

(Karpowitz 2008, p. 3). Although it is 

not known whether pygmy rabbits are 

benefiting from these types of habitat 

restoration actions across their range, 

some actions implemented for other 

species may benefit pygmy rabbits (e.g., 

pinyon-juniper removal for greater sagegrouse) (Larrucea 2007, p. 127). 

At the State level, control of invasive 

plant species is sometimes encouraged. 

Some States require landowners to 

control noxious weeds on their 

property, but the types of plants 

considered to be noxious weeds vary by 

state. For example, only Oregon, 

California, Colorado, Utah, and Nevada 

list medusa head as a noxious, regulated 

weed, but medusa head can be 

problematic in other states (e.g., Idaho). 

Cheatgrass is not considered an official 

noxious weed within the range of the 

pygmy rabbit. Although we do not know 

how these regulations affect sagebrush 

habitats, States have regulations 

regarding invasive species in place. 

Summary of Conservation Strategies 

and Actions 

All seven States within the range of 

the pygmy rabbit mention this species 

in their Comprehensive Wildlife 

Conservation Strategies and indicate 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60549 

that the species or its habitat deserves 

special management considerations now 

and in the future. While we are not 

aware of any States implementing 

conservation actions specifically for the 

pygmy rabbit, we are aware of initiatives 

to restore the sagebrush ecosystem 

within the range of the pygmy rabbit 

over time. Many states encourage the 

control of invasive plant species. 

Conservation strategies and actions 

carried out in consideration of the 

pygmy rabbit will benefit it now and in 

the future. 

Therefore, based on the best available 

scientific and commercial information, 

we conclude that conservation strategies 

and actions for pygmy rabbits or their 

habitat do not pose a significant threat 

to the pygmy rabbit now or in the 

foreseeable future. 

Summary of Factor A 

We have assessed the best available 

scientific and commercial data on the 

magnitude and extent of the impacts of 

agriculture, sagebrush treatment, 

livestock grazing, nonnative and 

invasive plant species, fire, urban and 

rural development (and associated 

facilities), mining, energy exploration 

and development (and associated 

facilities), habitat fragmentation, greater 

sage-grouse conservation actions and 

other conservation actions on pygmy 

rabbit habitat. We find that these threats 

do not significantly, either singly or 

cumulatively, impact the pygmy rabbit 

to such an extent within the foreseeable 

future such that listing under the Act as 

an endangered or threatened species is 

warranted. While sagebrush habitat loss 

and fragmentation has occurred within 

the range of the pygmy rabbit due to 

various anthropogenic and natural 

activities as discussed above and likely 

will continue at some level in the 

future; our review of the best available 

information reveals only a handful of 

specific areas where sagebrush loss or 

degradation is occurring in occupied 

pygmy rabbit habitat. Due to the pygmy 

rabbit’s patchy habitat distribution 

across the landscape, the scope of loss 

or modification of sagebrush habitat in 

general does not equally relate to loss or 

modification of pygmy rabbit habitat. 

The activities listed above are likely to 

continue into the future with some 

increases occurring. However, pygmy 

rabbit populations continue to occur 

throughout the species’ current known 

range, including historically occupied 

locations, and some new populations 

have been found in recent years, despite 

numerous activities occurring within its 

habitat. 

We conclude that the best scientific 

and commercial information available 

indicates that the pygmy rabbit is not 

now, or in the foreseeable future, 

threatened by the present or threatened 

destruction, modification, or 

curtailment of its habitat or range to the 

extent that listing under the Act as an 

endangered or threatened species is 

warranted at this time. 

Factor B: Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

We have no information that the 

pygmy rabbit is being used for 

commercial or educational purposes. 

Hunting 

Impacts due to hunting include injury 

or death with the potential for 

impacting population numbers. Some 

individuals have suggested that pygmy 

rabbits were not readily hunted in the 

past. Bailey (1936, p. 112) indicated an 

individual from Nevada reported that 

pygmy rabbits were not eaten by locals 

because of the strong sage taste. Later 

Larrison (1967, p. 64) said, ‘‘[Pygmy 

rabbits] flesh tastes of sagebrush, 

rendering it unfit as food.’’ 

In Idaho, Fisher (1979, p. 29) 

recommended that bag limits be 

monitored, especially where habitat was 

declining, because with the pygmy 

rabbit’s lower reproductive potential as 

compared to other rabbits, fewer surplus 

animals may be available to hunters. 

Sanchez (2007, p. 90) reports of an 

illegal harvest of two pygmy rabbits in 

her Idaho study area during 2004 to 

2005. Rauscher (1997, pp. 10-11) 

reported pygmy rabbit hunting in 

southwestern Montana, but stated that 

hunting did not appear to be a 

significant mortality factor. Williams 

(1986, p. 52) stated that although 

hunting impacts were not known in 

California, he thought that hunters 

probably did not kill many pygmy 

rabbits because the species was quite 

secretive and rarely left dense brush. 

Pritchett et al. (1987, p. 231) reported 

that, according to locals near Loa, 

Wayne County, Utah, pygmy rabbits 

have been ‘‘extensively hunted’’ along 

with black-tailed jackrabbits (Lepus 

californicus) and cottontails. Where he 

was able to access portions of his 

previous study area outside Cedar City, 

Utah, Janson (2002, p. 32) found spent 

shotgun shells. He thought it was 

probable that some pygmy rabbits were 

shot because most hunters cannot 

distinguish between pygmy rabbits and 

cottontails. 

We are aware that rabbit drives 

occurred (Bacon et al. 1959, p. 281; 

Jackman and Long 1964, p. no page 

number), but there is little 

documentation on the impacts to pygmy 

rabbits. For example, Bacon et al. (1959, 

p. 281) collected rabbits, mostly by 

organized drives of hunters who shot 

them, to gather ectoparasitic (parasite on 

outer surface of an animal) information 

on wild rabbits and rodents in eastern 

and central Washington between 1951 

and 1956; of the 1,040 rabbits collected, 

representing four species, only one was 

a pygmy rabbit. It is unknown if the 

single collection indicates pygmy 

rabbits are less vulnerable to drives or 

if numbers were reduced in that area at 

the time. 

Jackman and Long (1964, p. no page 

number) documented, with a 

photograph, that a rabbit drive occurred 

in Oregon in 1911. The drive resulted in 

1,811 rabbits being captured, but the 

species of rabbits were not identified 

nor was the location of the drive. The 

photograph is courtesy of the Schminke 

Museum, Lakeview, Lake County, 

Oregon, so the drive could have 

occurred in that county. We do not have 

any additional information on rabbit 

drives occurring within the range of the 

pygmy rabbit. 

Currently, only three (California, 

Nevada, and Montana) of the seven 

States within the species range allow 

hunting of pygmy rabbits. For these 

States, the State Wildlife Boards of 

Commissioners set hunting regulations 

yearly. In California, for the 2009 to 

2010 Upland Game Season, hunting of 

pygmy rabbits is allowed from July 1 to 

January 31 with a bag limit of 5 per day 

and 10 in possession (California 

Department of Fish and Game 2010, 

http://www.dfg.ca.gov/regulations/09- 

10-upland-sum.html, accessed July 20, 

2010). The 2009-2010 pygmy rabbit 

hunting season in Nevada opened 

October 10 and closed February 28 with 

a daily limit of 10 and a possession limit 

of 20 (Nevada Department of Wildlife, 

2009, no page numbers). For Montana, 

the pygmy rabbit is considered a 

nongame species and there is no 

protection from hunting. Pygmy rabbits 

can be hunted year-round with no bag 

limits (Montana Department of Fish 

Wildlife and Parks 2010, http:// 

fwp.mt.gov/wildthings/ 

livingWithWildlife/rabbits/ 

rab_ctrl.html). For these three States, 

harvest data are collected through 

hunter surveys but the various rabbit 

species are not distinguished from one 

another so the number of pygmy rabbits 

harvested in these States per year is not 

known. 

Summary of Hunting Impacts 

While it has been reported that pygmy 

rabbits have been hunted over the years 

and specifically in Idaho, Nevada, and 

Utah, only three (Montana, California, 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60550 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

and Nevada) of the seven States within 

the range of the pygmy rabbit currently 

allow hunting of this species. Historical 

harvest records are not available, but 

information indicates a reluctance to eat 

pygmy rabbits due to their strong sage 

taste as well as difficulty in hunting 

them due to their secretive nature. The 

number of pygmy rabbits taken more 

recently through hunting is not 

discernable because of the method by 

which present-day data are collected in 

States that allow hunting. Based on the 

best scientific information available, we 

conclude that hunting is not a 

significant threat to the pygmy rabbit 

now or in the foreseeable future. 

Research 

Research activities on pygmy rabbits 

that involve trapping, handling, and 

holding them for a period of time can 

result in mortality from exposure, 

injury, trap predation, intra-specific 

fighting, and capture stress (Bailey 1936, 

pp. 111-112; Severaid 1950, p. 2; Wilde 

1978, p. 96; Gahr 1993; Rauscher 1997, 

p. 9). Mortality rates for captured pygmy 

rabbits have been reported as 3 percent 

(Gahr 1993, p. 37), 5 percent (Wilde 

1978, p. 96), and 19 percent (Rauscher 

1997, p. 9). Individuals may be killed 

for specimen collections (Grinnell et al. 

1930, pp. 553-555; Bailey 1936, p. 111; 

Severaid 1950, p. 2). Investigations may 

also involve digging out burrows, 

stepping on burrows accidentally, 

measuring vegetation and other site 

characteristics near burrows, and other 

general disturbance in the study area 

(Janson 1946, p. 69; Bradfield 1974, pp. 

17, 21-22, 26; Green 1978, pp. 4-6; Gahr 

1993, pp. 54-60; Katzner 1994, pp. 6-12; 

Rauscher 1997, pp. 6, 12). Katzner 

(1994, p. 111) reported that all of his 

collared rabbits (10) died. He suggested 

the weight of the radio collars, and 

increased grooming as a result of their 

presence, may have increased a rabbits’ 

vulnerability to predation. Rachlow and 

Witham (2004a, p. 3) reported 1 pygmy 

rabbit mortality out of the 15 trapped 

during their survey efforts. The trap 

contained a long-tailed weasel (Mustela 

frenata), and it was unclear if the weasel 

killed the rabbit prior to entering the 

trap, entered the trap after the rabbit 

was captured in the trap, or entered the 

trap with the rabbit simultaneously. 

Sanchez (2007, p. 90) reported two 

deaths related to her study due to 

collars entrapping the lower jaw of the 

pygmy rabbit. Flinders et al. (2005, p. 

36) captured two pygmy rabbits, placing 

radio-collars and ear tags on them. They 

reported one died due to a loose collar; 

the other bit the collar off but was 

captured by a remote camera 339 yd 

(310 m) away from the initial capture 

site. 

Summary of Research Impacts 

The documented mortalities due to 

research activities are relatively few in 

number, occur in limited areas, and 

occur over limited time periods. Most of 

these reported mortalities are 

documented in studies conducted 

before 1997 and few mortalities have 

been reported in recent documents. 

Therefore, based on our review of the 

best available scientific information, we 

conclude that research activities are not 

a significant threat to the pygmy rabbit 

now or in the foreseeable future. 

Summary of Factor B 

Currently only three States allow 

hunting of pygmy rabbits; this is a 

reduction from the historic condition 

where all of the states considered in this 

finding allowed hunting. We found no 

data regarding long-term historical or 

recent hunting data that would clarify 

past or current hunting pressure on the 

pygmy rabbit across its range. While 

there is a potential for populations at 

low levels to be harmed by hunting and 

poaching mortality, our review of the 

best scientific and commercial 

information indicates hunting is not a 

significant threat to the pygmy rabbit. 

Research activities have been a source 

of mortality for pygmy rabbits, although 

our review of the best scientific 

information suggests this is a very minor 

level of mortality and does not pose a 

significant threat to the species. 

We have assessed the best available 

scientific and commercial data on the 

magnitude and extent of the impacts of 

hunting and research activities on 

pygmy rabbits. Based on that 

information, we conclude that the best 

scientific and commercial information 

available indicates that the pygmy rabbit 

is not now, or in the foreseeable future, 

threatened by the overutilization for 

commercial, recreational, scientific, or 

educational purposes to the extent that 

listing under the Act as an endangered 

or threatened species is warranted at 

this time. 

Factor C: Disease or Predation 

Disease 

Possible effects of disease include 

weakening of individuals which may 

increase their vulnerability to predation. 

Serious disease outbreaks can impact 

population size and number. Pygmy 

rabbits reportedly can harbor high 

parasite loads (Janson 1946, p. 90; Wilde 

1978, p. 107; Gahr 1993; WDFW 1995; 

66 FR 59734). These parasites include 

ticks (e.g., Dermacenter paramapterus, 

D. anersoni, Haemaphysalis leporispalustris), fleas (e.g., Cediopsylia 

inaequalis, Odontopysilys dentatus), 

lice (not specified), and bot flies (e.g., 

Cuterebra maculata) (Davis 1939, p. 

365; Janson 1940, pp. 25-27; Janson 

1946, p. 90; Larrison 1967, p. 64; Wilde 

1978, pp. 13-16; Gahr 1993; Rauscher 

1997, p. 12) which can be vectors of 

disease. 

Plague and tularemia can be found in 

leporid populations, but they have not 

been confirmed in pygmy rabbits. 

Plague is a bacterial disease that is 

transmitted by fleas infected with the 

bacterium, Yersinia pestis. Tularemia is 

caused by the bacterium Francisella 

tularensis and is commonly transmitted 

by ticks. These diseases often spread 

rapidly and can be fatal (Quan 1993, p. 

54). Hall (1946, p. 618), in Nevada, 

thought that pygmy rabbits were killed 

by tularemia based on his general 

observations which were not specified. 

Gahr (1993, p. 22) found bot flies on two 

pygmy rabbits located in the grazed area 

of her study in Washington, indicating 

cattle may act as a vector for spreading 

parasites and possibly disease. She 

commented that parasitism by bot flies 

is not necessarily detrimental to the 

rabbit, and additional study is needed to 

determine if cattle presence increases 

the incidence of ectoparasites for pygmy 

rabbits. 

Red Willow Research Inc. (2002, p. 

108) expressed concern that the 

transport and transmission of diseases 

by domestic livestock to pygmy rabbits 

could be a threat. Red Willow Research 

Inc. (2002, p. 108) raised the concern 

that a calicivirus, such as Rabbit 

Hemorrhagic Disease (RHD), could 

explain declines in pygmy rabbit 

populations and suggests additional 

research is needed. The Committee for 

the High Desert et al. (2003, p. 150) 

indicated that West Nile Virus is a 

growing concern for native wildlife, 

including pygmy rabbits. We have no 

reports of disease epizootics (outbreaks) 

occurring in pygmy rabbits in the range 

considered in this finding. Janson (2002, 

p. 30) did not observe any obviously 

diseased pygmy rabbits in his earlier 

work in the 1940’s. Oliver (2004, p. 36) 

reported that in Utah, the effects of 

parasites and disease on pygmy rabbit 

populations are not known. Parasites 

and disease have not been regarded as 

a major threat to pygmy rabbits (Wilde 

1978, p. 141; Green 1979, p. 25). The 

final rule for the Columbia Basin DPS 

pygmy rabbit indicated disease, 

including plague, was a significant 

potential threat to the remaining, small 

populations (68 FR 10405). A number of 

captive Columbia Basin pygmy rabbits 

have died of mycobacteriosis and 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60551 

coccidiosis (WDFW 2005a; Harrenstien 

et al. 2006 cited in Service 2007, p. 21). 

It is unclear if these two diseases were 

introduced into the captive breeding 

population from wild caught 

individuals or by some other means. 

Mycobacteriosis and coccidiosis have 

not been reported in pygmy rabbits 

occurring in the rest of its range. 

Summary of Disease Impacts 

Though pygmy rabbits can harbor 

high parasite loads, there is no evidence 

that this is negatively impacting pygmy 

rabbit populations. Through our review 

of the best scientific and commercial 

information we found no reports of 

disease epizootics occurring in pygmy 

rabbit populations anywhere within the 

range of the species. Therefore, based on 

our review of the best available 

information, we conclude that disease is 

not a significant threat to the pygmy 

rabbit now or in the foreseeable future. 

Predation 

Predation of pygmy rabbits has been 

reported in Idaho, Nevada, and Utah. 

According to Green (1979, p. 25) 

predation is the main cause of pygmy 

rabbit mortality. The annual mortality 

rate of adult pygmy rabbits may be as 

high as 88 percent, and one researcher 

found that more than 50 percent of 

juveniles can die within about 5 weeks 

of their emergence (Wilde 1978, pp. 

139-140). Estes-Zumpf and Rachlow 

(2009, p. 367) found mortality rates 

were 69 percent and 88.5 percent for 

male and female juvenile pygmy rabbits, 

respectively, in their study area in eastcentral Idaho. The mortality rate was 

highest within two months of emerging 

from the natal burrow. However, 

mortality rates for adult and juveniles 

can vary considerably between years 

and for juveniles between cohorts 

within years (Wilde 1978, pp. 85-95, 

138-140). 

While pygmy rabbits have numerous 

predators, they have adapted to their 

presence (Janson 1946, pp. 28-29; 

Gashwiler et al. 1960, p. 227; Green 

1978, p. 37; Wilde 1978, pp. 141-143). 

Junipers provide perches for avian 

predators and may provide habitat for 

mammalian predators (Larrucea and 

Brussard 2008b, p. 1640). However, 

Larrucea and Brussard (2008b) do not 

provide actual losses of pygmy rabbits 

to predators utilizing pinyon-juniper 

habitat. If levels of predation are too 

high, local populations may be 

suppressed below a point at which they 

can be maintained. Sagebrush habitat 

with damaged structural components 

may increase the pygmy rabbit’s 

vulnerability to predation. Weiss and 

Verts (1984, p. 569) thought that use of 

denser and taller sagebrush habitats by 

pygmy rabbits was related to predator 

avoidance. Katzner (1994, p. 52) 

documented that raptors were a cause of 

mortality and denser sagebrush cover 

deterred these avian predators. In Idaho, 

Sanchez (2007, pp. 90-91) attributed 42 

percent of natural mortalities to 

mammalian and avian predation; the 

cause of death in 58 percent of the 

mortalities could not be determined. 

Summary of Predation Impacts 

Pygmy rabbits are a prey species and 

predation has been stated by some 

researchers as the main cause of 

mortality. Annual mortality rates for 

adult and juvenile pygmy rabbits can be 

high, but these rates can vary 

considerably between years and 

between juvenile cohorts within 

particular years. Predation is a natural 

part of population dynamics for any 

species and results in the death of 

individuals. Based on our review of the 

best available scientific information, we 

did not find any indication of predation 

being a significant threat to the pygmy 

rabbit in all or a significant portion of 

its range. The Service is not aware of 

any predators that potentially pose a 

significant threat to the species. We 

therefore conclude that the available 

information indicates that the pygmy 

rabbit is not threatened by predation 

now or in the foreseeable future. 

Summary of Factor C 

Disease and predation may be 

significant threat factors to local or 

isolated pygmy rabbit populations; 

however, based on our review of the 

best available scientific information, we 

did not find any information to indicate 

significant threats from either disease or 

predation Habitat degradation and 

fragmentation may increase the effects 

of parasites, disease, and predation on 

some populations. We do not have any 

reports indicating that RHD or West Nile 

Virus is a significant threat to pygmy 

rabbits, nor are we are aware of reports 

of disease epizootics occurring in wild 

pygmy rabbits anywhere within the 

species’ range. Therefore, we conclude 

that the best scientific and commercial 

information available indicates that the 

pygmy rabbit is not now, or in the 

foreseeable future, threatened by disease 

or predation to the extent that listing 

under the Act as an endangered or 

threatened species is warranted at this 

time. 

Factor D: Inadequacy of Existing 

Regulatory Mechanisms 

Local Laws and Regulations 

We are not aware of any county or 

city ordinances that provide protection 

specifically for pygmy rabbits or their 

habitat on private lands. We recognize 

that county or city ordinances that 

address agricultural lands, 

transportation, and zoning for various 

land uses have the potential to influence 

pygmy rabbits or their habitat (zoning 

that protects open space might retain 

suitable pygmy rabbit habitat; a housing 

development and associated roads 

might destroy or fragment habitat). We 

found no detailed information regarding 

the nature or extent of zoning efforts 

within the species’ range and its direct 

or indirect effects on pygmy rabbit 

habitat or populations. 

State Laws and Regulations 

Currently, hunting of pygmy rabbits is 

allowed in three of the seven States 

within the species’ range (California, 

Nevada, and Montana). In California, for 

the 2009 to 2010 Upland Game Season, 

hunting of pygmy rabbits is allowed 

from July 1 to January 31 with a bag 

limit of 5 per day and 10 in possession 

(California Department of Fish and 

Game, 2010, http://www.dfg.ca.gov/ 

regulations/09-10-upland-sum.html, 

accessed July 20, 2010). In Nevada, the 

2009-2010 pygmy rabbit hunting season 

opened on October 10 and closed on 

February 28 with a daily limit of 10 and 

a possession limit of 20 (Nevada 

Department of Wildlife, 2009, no page 

numbers). For Montana, the pygmy 

rabbit is considered a species of 

concern, nongame species and there is 

no protection from hunting. Pygmy 

rabbits can be hunted year-round with 

no bag limits (Montana Department of 

Fish Wildlife and Parks 2010, http:// 

fwp.mt.gov/wildthings/ 

livingWithWildlife/rabbits/ 

rab_ctrl.html). Due to the manner of 

data collection, the numbers of pygmy 

rabbits harvested in these States each 

year is not known. 

Hunting of pygmy rabbits is not 

allowed in Idaho or Wyoming where 

they are considered a species of special 

concern, or in Utah where they are 

considered a sensitive species. Nor is 

hunting allowed in Oregon where the 

pygmy rabbit is considered a sensitive 

species and protected under State law. 

In Wyoming, many oil and gas 

development projects occurring on 

private lands fall under the jurisdiction 

of the Wyoming Industrial Siting Act 

(cited in Lance 2008, p. 6). This requires 

the Industrial Siting Administration to 

consult with Wyoming Game and Fish 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60552 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Department to address impacts; and 

appropriate mitigation is required prior 

to issuance of permits (Lance 2008, pp. 

5-6). As mentioned above, monitoring 

for restoration and mitigation activities 

are in the early stages. We do not know 

whether pygmy rabbits are benefiting 

from any mitigation that may have been 

required under reviewed projects, but 

restoration of sagebrush habitat is likely 

to positively impact pygmy rabbits. 

Summary of State Laws and Regulations 

Impacts 

Hunting of pygmy rabbits is allowed 

in three of the seven States. In 

Wyoming, many oil and gas projects 

located on private lands will be 

reviewed by that state’s wildlife agency 

with appropriate mitigation required 

that may benefit pygmy rabbits. The best 

available information indicates that the 

inadequacy of existing State laws do not 

threaten the pygmy rabbit. 

Federal Laws and Regulations 

A large portion of the sagebrush 

community with the potential to 

support pygmy rabbits occurs on BLM 

lands. 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-administered lands. Section 

102 (a)(8) of FLPMA specifically 

recognizes that wildlife and fish 

resources are the uses for which these 

lands are to be managed. 

We acknowledge that data to evaluate 

the effectiveness of BLM’s programs on 

pygmy rabbit conservation are not 

available. Whether the various BLM 

stipulations issued related to oil and gas 

activities specific to the greater sagegrouse (75 FR 13978) also reduce 

impacts from these activities to pygmy 

rabbits and their habitats is unknown. 

The BLM has management and 

permitting authorities to regulate and 

condition oil and gas lease permits 

under FLPMA and the Mineral Leasing 

Act (MLA) (30 U.S.C. 181 et seq.). BLM 

usually incorporates stipulations as a 

condition of issuing leases. The BLM’s 

planning handbook has programspecific guidance for fluid materials 

(including oil and gas) that specifies 

that Resource Management Plan (RMP) 

decision-makers will consider 

restrictions on areas subject to leasing, 

including closures, and lease 

stipulations (BLM 2000, Appendix C, p. 

16). 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. 16). 

BLM’s RMPs are the basis for all 

actions and authorizations involving 

BLM-administered land 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 each 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. These plans address 

livestock grazing, oil and gas field 

development, travel management 

(managing vehicle routes and access), 

wildlife habitat management, and other 

activities. Activity plan decisions 

normally require National 

Environmental Policy Act (NEPA) (42 

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

BLM has designated the pygmy rabbit 

as a special status species/bureau 

assessment species in five (Idaho, 

Montana, Nevada, Oregon, and 

Wyoming) of the seven States in which 

it occurs. BLM policy and guidance for 

species of concern occurring on BLM 

managed land is addressed under BLM’s 

6840 Manual, ‘‘Special Status Species 

Management’’ (BLM 2008c entirety). 

This manual provides agency policy and 

guidance for the conservation of special 

status plants and animals and the 

ecosystems on which they depend, but 

it is not a regulatory document. The 

objectives for BLM special status species 

are ‘‘ to conserve and/or recover ESAlisted species and the ecosystems on 

which they depend so that ESA 

protections are no longer needed for 

these species and to initiate proactive 

conservation measures that reduce or 

eliminate threats to Bureau sensitive 

species to minimize the likelihood of 

and need for listing of these species 

under the ESA.’’ (BLM 2008c, p. 3). 

There has been an increased focus on 

the roles that state, county, and private 

entities have in controlling invasive 

plants. For example, the Noxious Weed 

Control and Eradication Act was passed 

in 2004 and incorporated into the Plant 

Protection Act. This Act is intended to 

assist eligible weed management entities 

to control or eradicate harmful 

nonnative weeds on both public and 

private lands. Additionally, Executive 

Order 13112 was signed on February 3, 

1999, establishing an interagency 

National Invasive Species Council in 

charge of creating and implementing a 

National Invasive Species Management 

Plan. The Management Plan directs 

federal efforts, including overall strategy 

and objectives, to prevent, control, and 

minimize invasive species and their 

impacts (National Invasive Species 

Council 2008, p. 5). However, the Order 

also directs the Council to encourage 

planning and action at local, tribal, 

state, regional, and eco-system levels to 

achieve the goals of the National 

Invasive Species Management Plan, in 

cooperation with stakeholders (e.g., 

private landowners, states) and existing 

organizations addressing invasive 

species. 

Noxious and invasive weed 

treatments on BLM lands involving 

reseeding can occur through the 

Emergency Stabilization and Burned 

Area Rehabilitation Programs. Invasive 

species control is a stated priority in 

many RMPs. For example, 76 of the 

RMPs included in BLM’s response to a 

data call claim that the RMP (or 

supplemental plans/guidance applicable 

to the RMP) require treatment of 

noxious weeds on all disturbed surfaces 

to avoid infestations of BLM-managed 

lands in the planning area (Carlson 

2008a cited in 75 FR 13977). We also 

note that it is possible that more RMPs 

specifically address invasive species 

under another general restoration 

category (75 FR 13977). 

BLM commonly uses herbicides on 

lands to control invasive plant species. 

In 2007, the BLM completed a 

programmatic EIS (BLM 2007c) and 

Record of Decision for vegetation 

treatments on BLM-administered lands 

in the western United States. This 

program approves the use of four new 

herbicides, provides updated analysis of 

18 currently used herbicides, and 

identifies herbicides that the BLM will 

no longer use on public lands. 

Information is unavailable on how 

frequently the programmatic EIS has 

been used for most states or whether 

actions implemented under this EIS 

have been effective; and while not 

authorizing any specific on-the-ground 

actions, it guides the use of herbicides 

for field-level planning. Site-specific 

NEPA analysis is still required at the 

project level (BLM 2007c, p. ES-1 to ES2). 

Another voluntary approach to 

control invasive plant species is the 

development of Cooperative Weed 

Management Areas (CWMAs). CWMAs 

are partnerships between federal, state, 

and local agencies, tribes, individuals, 

and interested groups to manage both 

regulatory noxious weeds and invasive 

plants in a county or multi-county 

geographical area. They function under 

a mutually developed memorandum of 

understanding and a locally developed 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60553 

strategic plan. The CWMAs can utilize 

federal funds for invasive plant control 

on non-federal land. As of 2005, Oregon, 

Nevada, and Utah had between 75 and 

89 percent of their state covered by 

CWMAs and/or county weed districts, 

while Idaho, Montana, Wyoming, and 

California had between 90 and 100 

percent coverage (Center for Invasive 

Plant Management 2008, 

www.weedcenter.org/ 

weed_mgmt_areas/wma_overview.html). 

BLM regulatory authority for grazing 

management is provided at 43 CFR part 

4100 (Regulations on Grazing 

Administration Exclusive of Alaska). 

Livestock grazing permits and leases 

contain terms and conditions 

determined by BLM to be appropriate to 

achieve management and resource 

condition objectives on the public lands 

and other lands administered by the 

BLM, and to ensure that habitats are, or 

are making significant progress toward 

being restored or maintained for BLM 

special status species (43 CFR 

4180.1(d)). Grazing practices and 

activities include the development of 

grazing related portions of 

implementation or activity plans, 

establishment of terms and conditions 

of permits, leases and other grazing 

authorizations, and range improvement 

activities such as vegetation 

manipulation, fence construction, and 

development of water for livestock. 

BLM grazing administration standards 

for a particular state or region must 

address habitat for endangered, 

threatened, proposed, candidate, or 

special status species, and habitat 

quality for native plant and animal 

populations and communities (43 CFR 

4180.2 (d)(4) and (5). The guidelines 

must address restoring, maintaining or 

enhancing habitats of BLM special 

status species to promote their 

conservation, and maintaining or 

promoting the physical and biological 

conditions to sustain native populations 

and communities (43 CFR 4180.2(e)(9) 

and (10). 

Information regarding assessments of 

rangelands is not available. During 2004 

through 2008, BLM conducted a 

national data call to collect information 

on the status of rangelands, rangeland 

health assessments, and measures that 

have been implemented to address 

rangeland health issues under their 

jurisdiction. The information collected 

was unusable to make broad 

generalizations about the status of 

rangelands or management actions 

because of inconsistency across the 

range regarding how questions were 

interpreted and answered. This limited 

the ability to use this information in 

understanding habitat conditions on 

BLM lands (75 FR 13976). 

Since 2005, the BLM has developed or 

is in the process of developing 

guidances to minimize impacts of 

renewable energy production on public 

lands. A Record of Decision for 

‘‘Implementation of a Wind Energy 

Development Program and Associated 

Land Use Plan Amendments’’ was 

issued in 2005. The Record of Decision 

outlines the Best Management Practices 

for the siting, development, and 

operation of wind energy facilities on 

BLM lands. A final programmatic EIS 

and Record of Decision for geothermal 

development were issued in 2008. The 

BLM is in the process of developing 

programmatic-level guidance for the 

development of solar energy projects. 

The draft programmatic EIS for solar 

energy is under development –available 

at http://www.blm.gov/wo/st/en/prog/ 

energy/epca_chart.html). 

Although we are uncertain which 

management direction the USFS is 

taking for the pygmy rabbit or whether 

pygmy rabbit habitat objectives and 

conservation measures have been 

incorporated into grazing allotment 

plans or Land and Resource 

Management Plan (LRMPs), the pygmy 

rabbit is designated as a USFS Sensitive 

Species in the Intermountain Region 

(R4) (USFS 2008b, p. 1). This includes 

southern Idaho, western Wyoming, 

Utah, and Nevada; the Northern Region 

(R1) which includes Montana (USFS 

2005, p. 2); and the Pacific Northwest 

Region (R6) which includes Oregon 

(USFS 2008c, p. 2). Sensitive species 

receive special management to ensure 

viability and to preclude trends that 

may lead to the need for Federal listing. 

There must be no impacts to sensitive 

species without an analysis of the 

significance of adverse impacts on 

populations, habitat and on the viability 

of the species as a whole (USFS Manual 

2672.1, cited in USFS 2008b, p. 1). 

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. NFMA specifies that all 

national forests and grasslands must 

have a LRMP (16 U.S.C. 1604(a)) to 

guide and set standards for natural 

resource management activities. NFMA 

also requires the USFS to incorporate 

standards and guidelines into LRMPs 

(16 U.S.C. 1604(c)). This has historically 

been done through a NEPA process. In 

order to meet overall multiple-use 

objectives, provisions are developed to 

manage plant and animal communities 

for diversity, based on the suitability 

and capability of a specific land area. 

The 1982 NFMA implementing 

regulations for land and resource 

management planning under which all 

existing forest plans were prepared, 

requires the USFS to manage habitat in 

order to maintain viable populations of 

existing native vertebrate species on 

National Forest System lands (47 FR 

43037, September 30, 1982). A new 

USFS planning regulation was 

published on April 21, 2008 (73 FR 

21,468) which superseded the 1982 rule. 

Plans developed under the new 

regulations would be more strategic and 

less prescriptive in nature than those 

developed under the 1982 planning 

rule. However, on June 30, 2009, the 

U.S. District Court for the Northern 

District of California vacated the new 

rule, and as a result, the rule is not 

currently in use by the USFS. 

Through the NFMA, LRMPs, and the 

On-Shore Oil and Gas Leasing Reform 

Act (1987; implementing regulations at 

36 CFR 228, subpart E), the USFS has 

the authority to manage, restrict, or 

include protective measures to mineral 

and other energy permits on their lands. 

Similar to BLM, existing protective 

standard stipulations on USFS lands 

occur for greater sage-grouse (75 FR 

13980). The USFS is a partner agency 

with the BLM on the draft programmatic 

EIS for geothermal energy development 

mentioned above. If finalized, the 

programmatic EIS will amend relevant 

LRMPs and will expedite the leasing of 

USFS lands with geothermal energy 

potential. 

Pygmy rabbit habitat also occurs on 

lands managed by other Federal 

agencies such as the Service and 

National Park Service (NPS). The 

National Wildlife Refuge System 

Administration Act (16 U.S.C. 668dd668ee) provides guidelines and 

directives for administration and 

management of all areas in the National 

Wildlife Refuge system. Refuges are 

managed for species conservation, 

consistent with direction in the National 

Wildlife Refuge System Administration 

Act, as amended, and related Service 

policies and guidance. The National 

Park Service Organic Act (16 U.S.C. §1, 

et seq.) states that the NPS will 

administer areas under their jurisdiction 

‘‘*** by such means and measures as 

conform to the fundamental purpose of 

said parks, monuments, and 

reservations, which purpose is to 

conserve the scenery and the natural 

and historical objects and the wildlife 

within and to provide for the enjoyment 

of the same in such manner and by such 

means as will leave them unimpaired 

for the enjoyment of future generations.’’ 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60554 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Summary of Federal Laws and 

Regulations Impacts 

A large portion of pygmy rabbit 

habitat occurs on lands administered by 

Federal agencies, including BLM, USFS, 

Service, and NPS. Numerous policies, 

guidance, and laws have been 

developed to assist the different 

agencies in management of these lands. 

The Bureau of Land Management 

policies and guidance address species of 

concern, actions covered by RMPs, and 

regulatory authority for grazing and oil 

and gas leasing and operating. The 

USFS policies and guidance address 

sensitive species and actions covered by 

LRMPs. The Service uses guidelines and 

directives under the National Wildlife 

Refuge System Administration Act for 

management of lands in the National 

Wildlife Refuge system. The National 

Park Service Organic Act provides 

management guidance to the NPS for 

management of lands administered by 

this agency. 

As discussed under Factors A and E, 

the best available information indicates 

that activities such as livestock grazing, 

mining, energy exploration and 

development, and recreational activities 

that are regulated by various policies, 

guidance, and laws on Federal lands are 

not significantly impacting pygmy 

rabbits. Therefore, we conclude that 

available information indicates that the 

existence of inadequate Federal laws 

and regulations are not a significant 

threat to the pygmy rabbit. 

Summary of Factor D 

Our assessment of threats based on 

the best available scientific and 

commercial data regarding the past, 

present and future loss or modification 

of pygmy rabbit habitat as discussed in 

Factor A, hunting activities as discussed 

in Factor B, and intra and inter-specific 

competition or recreational and non 

recreational vehicle use as discussed 

under Factor E lead us to conclude that 

the inadequacy of existing regulatory 

mechanisms is not a threat to the pygmy 

rabbit. Therefore, the best available 

scientific and commercial information 

indicates that the pygmy rabbit is not 

now, or in the foreseeable future, 

threatened by the inadequacy of existing 

regulatory mechanisms to the extent 

that listing under the Act as an 

endangered or threatened species is 

warranted at this time. 

Factor E: Other Natural or Manmade 

Factors Affecting the Species Continued 

Existence 

Several other potential threats have 

been mentioned as possibly negatively 

impacting pygmy rabbit populations 

including: (1) intra- and inter-specific 

competition; (2) small or isolated 

populations; (3) natural stochastic 

(random) events such as floods and 

drought; (4) climate change; (5) 

recreational activities; (6) mortality 

caused by collisions with vehicles; and 

(7) life history traits of a habitat 

specialist. 

Intra- and Inter-specific Competition 

While intra-specific competition 

likely occurs both under normal and 

stressful environmental conditions, we 

are not aware of any scientific 

information documenting or suggesting 

that such competition for food and 

space is negatively impacting pygmy 

rabbits at this time. 

As pygmy rabbits are habitat 

specialists, inter-specific competition 

with other herbivores for sagebrush 

such as jackrabbits, pronghorn, and 

mule deer could occur. Numerous 

researchers have mentioned other 

leporid species, namely black-tailed and 

white-tailed (Lepus townsendii) 

jackrabbits, and mountain cottontails 

(Silvilagus nuttallii) as occurring in the 

same areas with pygmy rabbits 

throughout their range. 

In Oregon, Anthony (1913, p. 23) 

mentioned that cottontails and blacktailed jackrabbits were observed in the 

same areas with pygmy rabbits. Bartels 

(2003, p. 93) also mentioned these two 

species were observed in areas used by 

pygmy rabbits. 

In Idaho, Merriam (1891, p, 13) 

mentioned white- and black-tailed jack 

rabbits and mountain cottontails in 

Pahsimeroi Valley where the pygmy 

rabbit also occurred. Roberts (2004, p. 4) 

mentioned that at one site in the Birch 

Creek area he flushed pygmy rabbits 

along with cottontails. Waterbury (2006, 

p. 10) found other rabbit and hare 

species (black-tailed and white-tailed 

jackrabbits, mountain cottontails) in 

association with pygmy rabbits in 

several locations, including Pahsimeroi 

and Big Lost River Valleys. 

In Montana, Rauscher (1997 p. 11) 

mentioned mountain cottontails and 

jack rabbits were observed at most 

pygmy rabbit sites. It was unclear if 

cottontails and pygmy rabbits were 

sharing burrows, if cottontails were 

replacing pygmy rabbits at burrows, or 

if cottontails were taking advantage of 

burrow availability. 

In California and Nevada, Larrucea 

and Brussard (2008a, p. 697) found 

cottontail rabbits may compete with 

pygmy rabbits and influence the 

relationship between understory growth 

and pygmy rabbit presence. Cottontails 

appear to occur more in areas with 

greater understory (Larrucea and 

Brussard 2008a, p. 697). Though pygmy 

rabbits consume primarily sagebrush, 

they will also eat forbs and grasses 

(Green and Flinders 1980b, p. 138). 

In California, Severaid (1950, p. 4) 

commented that white- and black-tailed 

jackrabbits and cottontails occupied the 

same habitats as pygmy rabbits. In 

northern Utah, Janson (1946, p. 40) also 

mentioned that these three species were 

occupying the same areas as pygmy 

rabbits. 

Grinnell et al. (1930, pp. 557-558) also 

noted the overlap of pygmy rabbit’s 

range with other leporids, namely 

mountain cottontail and black-tailed 

jackrabbit ranges. The other species 

occurred within or near the same 

territories as pygmy rabbits throughout 

all of their ranges, but mountain 

cottontails and black-tailed jackrabbits 

ranged over a much larger area than the 

pygmy rabbit. They suggested that the 

differentiation of each is mainly due to 

conditions outside of the range of the 

pygmy rabbit and these conditions may 

limit the territory of the pygmy rabbit. 

Conde (1982, p. 4) compared pygmy 

rabbit and black-tailed jackrabbit use in 

sagebrush-greasewood habitat in Cassia 

County, Idaho. She found in summer 

that pygmy rabbits selected areas with 

abundant grass while jackrabbits 

selected areas with abundant forbs. 

During the fall-winter period shrubs 

played an important role for both 

species, but pygmy rabbits fed on 

sagebrush leaves and young stems 

(Johnson 1979, cited in Conde 1982, p. 

19) and jackrabbits on 2–year old woody 

stems (Currie and Goodwin 1966, cited 

in Conde 1982, p. 19). Spatial 

distribution and exploitation of different 

vegetation in the summer allowed a 

sympatric relationship to occur between 

these two species (Conde 1982, p. 3). 

Grazing competition with livestock 

will depend on the range conditions and 

grazing practices that vary across the 

range of the pygmy rabbit. While 

researchers have documented pygmy 

rabbit in livestock use areas and the 

potential impacts to pygmy rabbits 

under Factor A, we are unaware of 

studies documenting aspects of 

potential forage competition between 

the two species within the range of the 

pygmy rabbit. We are aware of one 

study conducted at Sagebrush Flat, 

Washington, by Siegel Thines et al. 

(2004, p. 532) that found Columbia 

Basin pygmy rabbits selected ungrazed 

areas over grazed areas when 

constructing burrows. Livestock grazing 

during late summer and fall reduced the 

availability of grass (and likely forbs) by 

about 50 percent in the grazed units 

until the following growing season. 

Grasses provided greater than 50 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60555 

percent and forbs greater than 30 

percent of the pygmy rabbit’s diet in 

winter at Sagebrush Flat. They did not 

find that Columbia Basin pygmy rabbits 

ate less grass in grazed areas or that they 

chose different diets relative to the 

availability between ungrazed and 

grazed areas before the yearly grazing. 

However, after yearly grazing the 

Columbia Basin pygmy rabbits may 

have had a harder time finding grasses 

and forbs in the grazed areas. Grazing 

reduced the nutritional quality of 

grasses in winter and spring. On grazed 

areas, grasses had less protein and more 

fiber than ungrazed areas. Shrubs were 

more fibrous in grazed areas than 

ungrazed areas in winter. However, 

grasses may not have been providing a 

more nutritious food source for 

Columbia Basin pygmy rabbits in winter 

as they provided about 50 percent less 

of the crude protein and 50 percent 

more fiber than sagebrush or rabbit 

brush. It is unclear why the Columbia 

Basin pygmy rabbits avoided grazed 

areas and may not be due to diet-related 

reasons not measured in the study. 

Other impacts of cattle grazing in pygmy 

rabbit habitat have been previously 

discussed under Factor A. 

In Montana, there is spatial overlap 

between big game (elk Cervus elaphus, 

mule deer Odocoileus hemionus, 

antelope Antilocapra americana) winter 

range, jack rabbits and greater sagegrouse, and the range of pygmy rabbits. 

Hence, inter specific competition with 

pygmy rabbits may result (Janson 2002, 

pp. 16-17). 

Summary of Intra- and Inter-specific 

Competition Impacts 

Most authors only mention observing 

these other rabbit and hare species 

while they were studying or searching 

for pygmy rabbits in Oregon, Idaho, 

Montana, California, Nevada, and Utah; 

few authors suggest that there is 

possible competition between or among 

the species that negatively impacts 

pygmy rabbits. One study demonstrates 

a sympatric relationship between pygmy 

rabbits and black-tailed jackrabbits in 

Idaho. It has been suggested in Montana 

that competition may occur between big 

game species and pygmy rabbits where 

they coexist. While livestock grazing 

occurs throughout the range of the 

pygmy rabbit, its impact on the species 

remains unclear as discussed under 

Factor A. Any possible negative impacts 

to pygmy rabbits may be related more to 

loss or degradation of sagebrush 

structure as opposed to loss or reduction 

of the grass or forbs understory. The best 

scientific and commercial information 

available does not provide any 

documentation that pygmy rabbits are 

adversely affected by intra-specific 

competition for food or space across 

their range. We know from numerous 

reports that there appears to be a long 

history of pygmy rabbits co-existing 

across their range, with other species, 

especially other rabbit and hare species. 

The available information does not 

document adverse effects of interspecific competition on pygmy rabbits 

from other species of rabbits or hares or 

other species. Therefore, based on the 

best available scientific and commercial 

information, we conclude that the intraor inter-specific competition is a not a 

significant threat to the pygmy rabbit 

now or in the foreseeable future. 

Small or Isolated Populations 

Small, restricted populations are more 

vulnerable to risks and more susceptible 

to extinction from naturally occurring 

stochastic environmental causes than 

populations with large numbers 

occurring over a large area (Shaffer 

1981, pp. 131-132). Small, isolated 

populations are also at a greater risk to 

the deleterious effects of demographic 

and genetic problems (Schaffer 1981, p. 

133). Random demographic effects (e.g., 

skewed sex ratios) and loss of genetic 

variability may result in individuals and 

populations being less able to cope with 

environmental change. 

As discussed in the Background 

Section, accurately estimating pygmy 

rabbit population size is complex 

because the number of active burrows 

may not be directly related to the 

number of individuals in a given area. 

Some individual pygmy rabbits appear 

to maintain multiple burrows and 

conversely some individual burrows are 

used by multiple individuals (Janson 

1940, p. 21; Janson 1946, p. 44; Gahr 

1993, pp. 66, 68; Heady 1998, p. 25). 

Pygmy rabbits may also use more than 

one burrow or burrow system at a 

specific time or during different times of 

the year (Purcell 2006, p. 96). 

It is possible that pygmy rabbits have 

a metapopulation structure and 

therefore, populations located across the 

range are not small or isolated because 

they are able to interact with 

neighboring populations if distance is 

not too great. Recent studies as 

mentioned in the Background section 

above, indicate that pygmy rabbit home 

ranges and dispersal capabilities are 

greater than previously thought. Genetic 

research has occurred in some areas of 

the species’ range, and we have 

information documenting little 

population substructure in areas 

supporting pygmy rabbit in Idaho 

indicating these populations are not 

isolated (Estes-Zumpf et al. 2010, p. 

215). 

Summary of Small or Isolated 

Populations 

The impacts of various potential 

threats can be more pronounced on 

small or isolated populations. However, 

the best available scientific and 

commercial information does not 

indicate that pygmy rabbit populations 

are isolated or occurring in small 

populations across the range, or that 

these are significant threats now or in 

the foreseeable future. 

Stochastic Events 

Natural stochastic events can 

significantly impact populations if they 

result in high mortality, habitat loss, or 

offer little or no possibility of 

recolonization. They are most 

significant for small or fragmented 

populations (Gilpin and Soule 1986, p. 

25). Flooding which may cause burrow 

abandonment, mortality, and erosion of 

deep soils has been mentioned as a 

concern for pygmy rabbits. Pygmy 

rabbits are known to use deeper soils 

found along drainages for their burrows 

(Flath and Rauscher 1995, p. 2). Bartels 

(2003, p. 103) mentions a large flood 

event in pygmy rabbit habitat in the 

Harney Basin, Oregon, in 1984, though 

it is not reported if animals were 

actually killed. Drought can reduce 

vegetative cover, potentially resulting in 

increased soil erosion and subsequent 

reduced soil depths, decreased water 

infiltration, and reduced water storage 

capacity (Connelly et al. 2004, p. 7-19), 

Pygmy rabbit populations could be 

impacted directly by loss of habitat 

(food and shelter) or indirectly through 

possible increased predation. Drought 

has not been reported as having a direct 

negative effect on pygmy rabbits. 

Summary of Stochastic Events Impacts 

While natural stochastic events most 

certainly have occurred within the range 

of the pygmy rabbit and may have 

impacted specific populations, such as 

in Oregon during a flood, they have not 

been documented as types of events that 

have played a significant role in 

population distribution, abundance, 

and/or trends for the pygmy rabbit 

within its range. The best available 

scientific and commercial information 

does not indicate that stochastic events 

are a significant threat to the pygmy 

rabbit now or in the foreseeable future. 

Climate Change 

The Service acknowledges that 

environmental changes resulting from 

climate change could facilitate invasion 

and establishment of invasive species or 

exacerbate the fire regime, possibly 

accelerating the loss of sagebrush 

habitats (Connelly et al. 2004, p. 7-18). 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60556 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

Increases in the expansion of pinyon 

and juniper woodlands in the Great 

Basin may have resulted from poor 

habitat management and climate change 

(Connelly et al. 2004, p. 7-7). However, 

the encroachment of pinyon-juniper 

into occupied pygmy rabbit habitat is a 

slow process, and pygmy rabbits may be 

able to inhabit those areas or shift their 

home range to adjacent areas if pinyonjunipers habitat becomes established at 

a site. 

One researcher has addressed 

potential impacts to pygmy rabbits due 

to climate change. In California and 

Nevada, Larrucea and Brussard (2008b, 

p. 1640) found extant historical pygmy 

rabbit sites averaged 515 ft (157 m) 

higher than extirpated sites. With local 

downward shift effect accounted for, 

overall upward elevation shift of extant 

sites was 721.8 ft (220 m); the 

researchers attributed this to climate. 

Over the last century, a 0.7 degree 

Celsius temperature increase has 

occurred, which correlates with a 

predicted elevational shift upwards of 

383.9 ft (117 m) (Peters 1989, cited in 

Larrucea and Brussard 2008b, p. 1640). 

Warmer temperatures are also expected 

to increase fire intensity and frequencies 

(Westerling et al. 2006, cited in Larrucea 

2007, pp. 63-64). Warming temperatures 

may continue to shift upward the lower 

elevational boundary of habitable 

pygmy rabbit sites. 

The prehistoric record for pygmy 

rabbits in the Great Basin indicates a 

wider distribution than today and 

declines have occurred since the end of 

the Pleistocene (Kurten and Anderson 

1972, p. 21; Findley et al., 1975, 

Gillespie 1984, Harris 1985, 1993a cited 

in Grayson 2006 pp. 2969-2970). The 

beginning of the middle Holocene in the 

Great Basin also saw a decline in pygmy 

rabbit abundance (Grayson 2006, pp. 

2971-2972). The decline is attributed to 

this period experiencing elevated 

temperatures and decreased 

precipitation in the Great Basin 

(Grayson 2006, p. 2972). A third decline 

in pygmy rabbit abundance in the Great 

Basin is associated with the 

development of pinyon-juniper 

woodland within the region (Grayson 

2006, pp. 2973-2974). Establishment of 

pinyon-juniper in this area and its 

associated decline in pygmy rabbit 

numbers is best explained by the loss of 

sagebrush-grass habitat (Grayson 2006, 

p. 2974). Pygmy rabbits occur in the 

prehistoric record in New Mexico 

(Grayson 2006, p. 2970), but they are not 

currently known to occur in the State, 

though sagebrush habitat does exist 

there. The habitat may have changed to 

such an extent since prehistoric times 

that it no longer provides appropriate 

habitat for pygmy rabbits. Butler (1972, 

p. 52) stated that the population of 

pygmy rabbits on the Eastern Snake 

River Plain was greater prior to 7,000 

years ago. The decline in abundance of 

pygmy rabbits and pocket gophers 

(common in grassy meadows) at the 

beginning of the 7th millennium B.P. 

and accompanied by a proportional 

increase in the pygmy rabbit may 

indicate a change in climate that had 

more impact on grasses and forbs than 

on sagebrush (Butler 1972, p. 52). 

A warming trend in the mountains of 

western North America is expected to 

decrease snow pack, accelerate spring 

runoff, and reduce summer flows 

(Intergovernmental Panel on Climate 

Change (IPCC) 2007, p. 11). Increased 

summer temperatures may increase the 

frequency and intensity of wildfires 

(IPCC 2007, p. 13). Recent warming is 

linked, in terrestrial ecosystems, to poleward and upward shifts in plant and 

animal ranges (IPCC 2007, p. 2). Climate 

projections predict the Great Basin 

region is likely to become warmer and 

drier (Peters and Lovejoy 1992, cited in 

Larrucea 2007, p. 63). 

It is difficult to predict local climate 

change impacts due to substantial 

uncertainty in trends of hydrological 

variables, limitations in spatial and 

temporal coverage of monitoring 

networks, and differences in the spatial 

scales of global climate models and 

hydrological models (Bates et al. 2008, 

p. 3). Climate change models that are 

currently available are not yet capable of 

making meaningful predictions of 

climate change for specific, local areas 

(Parmesan and Matthews 2005, p. 354). 

Thus, while the best available 

information indicates that climate 

change has the potential to affect 

habitats used by pygmy rabbits in the 

Great Basin in the long-term, there is 

much uncertainty regarding which 

habitat attributes (including sagebrush, 

grass, and forbs communities) could be 

affected, and the timing, magnitude, and 

rate of their change as it relates to 

pygmy rabbits and their needs. 

Summary of Climatic Change Impacts 

Extant historical populations may 

indicate an upward shift in elevation 

due to climatic changes or this shift may 

be due to other unknown factors. The 

prehistoric record shows the range of 

the pygmy rabbit occurred over a larger 

area than today, and the range 

contraction has been attributed, in part, 

to increased temperatures and decreased 

precipitation. It is reasonable to assume 

that pygmy rabbits of today may be 

likewise affected in the Great Basin due 

to possible warmer and drier conditions. 

Climate change could also facilitate the 

establishment of invasive plant species 

or exacerbate the fire regime. Pinyon 

and juniper woodland expansion may 

increase, however this may be a slow 

process and may result in less sagebrush 

habitat being available for the pygmy 

rabbit in the future. However, while 

there is some evidence to suggest there 

may be an upward shift in elevation or 

contracted range due to climatic 

changes, we have no information to 

suggest that climate change will 

significantly affect the pygmy rabbit. 

Based on our review of the available 

information, there is no demonstrated 

direct link between predicted climate 

change and reduced abundance and 

survival of pygmy rabbits. The best 

scientific and commercial information 

currently available does not indicate 

that climate change is a significant 

threat to the species now or in the 

foreseeable future. 

Recreational Activities 

Recreational activities, especially offhighway vehicle/off-road vehicle (OHV/ 

ORV) and snowmobile use, have the 

potential to be a threat to pygmy rabbits 

and their sagebrush habitat by 

disturbing individuals through 

excessive noise, damaging sagebrush, or 

damaging burrows or subnivian tunnels. 

Additionally, recreation could increase 

the spread of weeds, and human 

presence and pets in a particular area. 

Much of the sagebrush habitat across the 

range of the pygmy rabbit is open to 

recreational use. Based on our review of 

the best available information, we found 

one document that indicates pygmy 

rabbits occupy an area used by OHV/ 

ORV users in Oregon (BLM 2008d, p. 6). 

In addition, in Idaho, Bradfield (1974, 

pp. 35-36) suggested that the pygmy 

rabbit depends on its hearing for 

predator detection and may be less 

active during windy periods when 

predator detection may be reduced. This 

study may suggest noise from a passing 

vehicle could make pygmy rabbits more 

vulnerable to predation. 

Summary of Recreational Activities 

Impacts 

Recreational activities occur in 

sagebrush habitat within the range of 

the pygmy rabbit, however, our review 

of the best scientific and commercial 

information available identified only 

one instance of recreational activities or 

areas where these activities may be 

directly or indirectly impacting pygmy 

rabbits. This area continued to support 

a number of active pygmy rabbit 

burrows. Therefore, we conclude that 

the best scientific and commercial 

information available does not indicate 

that recreational activities are a 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60557 

significant threat to the pygmy rabbit 

now or in the foreseeable future. 

Vehicle Collisions 

Roads are known to exist throughout 

the range of the pygmy rabbit. Jones 

(1957, p. 274) mentions a pygmy rabbit 

winter road kill in California north of 

Crowley Lake, Mono County, and in 

Wyoming a study mentions a previously 

reported road kill near Pinedale (Purcell 

2006, p. 8). Bradfield (1974, p. 3) 

suggested that pygmy rabbits were 

reluctant to cross open areas based on 

the lack of observed highway mortality 

(Gordon 1932, Sperry 1933, Smith 1943, 

cited in Bradfield 1974, p. 3). We are not 

aware of any documentation of pygmy 

rabbit mortalities due to snowmobiles or 

OHVs and ORVs. Additionally, there is 

no indication that vehicle mortalities 

have increased, or will increase in the 

future, as the density of roads have 

increased across the range of the 

species. 

Summary of Vehicle Collisions Impacts 

While we are aware of reports of road 

mortalities in Wyoming and California 

related to pygmy rabbits, they are few in 

number with low mortalities 

documented. We conclude that 

populations are able to recover from 

these types of limited, individual losses. 

Based on our review of the best 

available information, we conclude that 

mortality due to vehicular collisions is 

not a significant threat to the pygmy 

rabbit now or in the foreseeable future. 

Habitat Specialist 

Because the pygmy rabbit is a habitat 

specialist and its habitat is fragmented 

across the landscape, the species’ life 

history traits could affect population 

viability. Pygmy rabbits appear to have 

small home ranges, are not evenly 

distributed across the species’ range, 

and may have poor dispersal 

capabilities (though recent information 

indicates home ranges and dispersal 

capabilities are greater than originally 

thought) influencing genetic diversity or 

its ability to move to a more favorable 

location if necessary in reaction to 

natural or manmade factors. Pygmy 

rabbits do not respond to abundant 

spring food supply by producing 

additional litters like other rabbits and 

therefore, may have lower reproductive 

capabilities (Wilde 1978, p. 145). These 

life history traits could contribute to 

population declines as habitat size and 

quality are reduced, however, they 

should not be a limiting factor to pygmy 

rabbits across large geographic areas 

when suitable habitat is extensive and 

in good condition. 

Summary of Habitat Specialist Impacts 

The pygmy rabbit is a habitat 

specialist. Life history traits such as 

small home ranges, uneven distribution 

across its range, poor dispersal 

capabilities and lower reproductive 

potential compared to other leporid 

species might suggest a concern for the 

long-term survival of the pygmy rabbit. 

However, recent studies as mentioned 

in the Background section above 

indicate that pygmy rabbit home ranges 

and dispersal capabilities are greater 

than previously thought. Genetic 

research (Estes-Zumpf et al. 2010, p. 

214) has occurred in some areas of the 

species’ range, and available 

information indicates the pygmy rabbit 

exhibits relatively high genetic 

diversity. The best available scientific 

and commercial information does not 

indicate that the pygmy rabbit is 

negatively impacted by current habitat 

fragmentation. The information 

available indicates pygmy rabbit 

populations continue to occur over a 

wide distribution of their current range. 

The pygmy rabbit survives almost 

exclusively on sagebrush for food 

(especially in winter) and shelter. 

Sagebrush are long-lived, stable species, 

resistant to most environmental 

impacts, except fire and some insects, 

and thus do not fluctuate widely in 

availability. The best available 

information does not indicate how the 

lack of producing additional litters 

specifically during times of abundant 

plant growth is detrimental to the 

species. However, as indicated in the 

background section, female pygmy 

rabbits are capable of producing an 

average of six young per litter with three 

litters possible in a year. The best 

available information shows that the 

pygmy rabbit’s natural life history 

characteristics have not limited the 

species across its range. Therefore, we 

conclude that being a habitat specialist 

is not a significant threat to the pygmy 

rabbit now or in the foreseeable future. 

Other Potential Threats 

In our 90–day petition finding, we 

identified other natural or manmade 

factors (facilities associated with grazing 

(tanks, pipelines, roads) may allow 

predators, OHV/ORV users, and hunters 

to access new terrain; activities on 

military facilities; and predator control 

to benefit livestock increases predation 

on pygmy rabbits) that might pose a 

threat to pygmy rabbits. However, for 

this analysis, we could find no 

supporting information to indicate that 

any of these factors are threatening 

pygmy rabbit populations. 

Summary of Factor E 

We have assessed the best available 

scientific and commercial data on the 

magnitude and extent of the potential 

threats of intra- and inter-specific 

relationships, small or isolated 

populations, stochastic events, climate 

change, recreational activities, vehicle 

collisions, and habitat specialist life 

history requirements of the pygmy 

rabbit. As discussed above, intra- and 

inter-specific relationships between and 

among pygmy rabbits and other species 

are natural and occur but do not 

constitute a significant threat to the 

species. The best available scientific and 

commercial information does not 

document that natural or anthropogenic 

pressures are negatively affecting these 

relationships. The best available 

information indicates that pygmy rabbit 

populations are not small or occurring 

in isolation across the range. While 

stochastic events have occurred and will 

continue to occur throughout the range 

of the species, there is no indication that 

these events are a significant threat to 

the pygmy rabbit largely due to the 

patchy distribution of the species and 

its preferred habitat. Vehicle collisions, 

while a potential threat, have been 

rarely reported, and we do not consider 

them to be a significant source of 

mortality. Projected climate change 

impacts across the range of the pygmy 

rabbit are generalized and are not 

considered to be a significant threat. 

The potential impact of pinyon-juniper 

woodland expansion into pygmy rabbit 

habitat is predicted to be slow with 

pygmy rabbits demonstrating a variety 

of responses. Recreational activities 

occur within the range of the pygmy 

rabbit, but no information is available to 

qualify or quantify the effect on 

populations, and we do not considered 

these activities to be a significant threat. 

There is no indication from the 

available information that the pygmy 

rabbit has been limited across its range 

based on its natural life history 

characteristics. There are many natural 

and manmade factors or activities that 

have occurred and will continue to 

occur within pygmy rabbit habitats 

within its range. As discussed in the 

distribution and trend section, the 

available information indicates pygmy 

rabbit populations continue to occur 

over a wide distribution of their current 

range, including historical locations, 

despite these various factors. Based on 

the best available scientific and 

commercial information, the pygmy 

rabbit is not now, or in the foreseeable 

future, threatened by other natural or 

manmade factors affecting the species to 

the extent that listing as endangered or 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60558 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

threatened under the Act is warranted at 

this time. 

Finding 

As required by the Act, we considered 

the five factors in assessing whether the 

pygmy rabbit is endangered or 

threatened throughout all or a 

significant portion of its range. We 

carefully examined the best scientific 

and commercial information available 

regarding the past, present, and future 

threats faced by the pygmy rabbit. We 

reviewed the petition, information 

available in our files, other available 

published and unpublished 

information, and we consulted with 

recognized pygmy rabbit experts and 

other Federal, State, and tribal agencies. 

We have identified and evaluated the 

potential threats as discussed under 

Factor A (agriculture, sagebrush 

treatment, livestock grazing, nonnative 

invasive plants, fire, urban and rural 

development, mining, energy 

exploration and development, habitat 

fragmentation, and greater sage-grouse 

conservation actions), and we 

acknowledge that most of these threats 

have occurred within the range of the 

pygmy rabbit and may have impacted 

some areas known to be, or to have 

been, occupied by pygmy rabbits based 

on site-specific information. Some or all 

of these activities are likely to continue 

at some level in the future. Available 

information does not indicate that the 

sagebrush lost or degraded due to 

agriculture, sagebrush treatment, urban 

and rural development, mining, habitat 

fragmentation, greater sage-grouse 

conservation actions, or other 

conservation actions has impacted large 

areas of suitable or occupied pygmy 

rabbit habitat resulting in significant 

occupied habitat or population losses. 

The impacts attributed to livestock 

grazing, while widespread across the 

pygmy rabbit’s range, have not resulted 

in documented measurable declines in 

pygmy rabbit numbers or populations. 

Based on the information available, we 

find that the potential threat of 

increasing energy exploration and 

development as well as the relationship 

between invasive nonnative plant 

species and fire regimes are not 

significant threats to the pygmy rabbit 

now or in the foreseeable future. There 

is no available information that 

indicates the magnitude or extent of 

pygmy rabbit sites that may have been 

lost or reduced in area or in population 

size due to these activities. Some of 

these events or actions that can result in 

the complete loss of sagebrush over 

large areas (i.e., sagebrush conversion to 

agriculture, sagebrush treatments, fire) 

likely resulted in the reduction of 

occupied habitat and loss of some 

pygmy rabbit populations. However, 

there is no evidence that this will 

significantly threaten the species in the 

foreseeable future. Therefore, based on 

our review of the best available 

scientific information, we find these 

potential threats, either singly or in 

combination with one another, are not 

significant threats now or in the 

foreseeable future, to pygmy rabbit 

habitat across its range. 

We have identified and evaluated the 

risks from overutilization for 

commercial, recreational, scientific or 

educational purposes. Available 

information indicates that historical or 

recent hunting pressure has not played 

an important role in population 

dynamics for the pygmy rabbit across its 

range. Three of the seven States 

discussed in this finding currently allow 

hunting of pygmy rabbits; this is a 

reduction from the past. Based on the 

best available information we find that 

hunting was not and is not a significant 

threat to pygmy rabbit populations 

across its range nor will it be in the 

foreseeable future. 

Research activities may result in 

adverse impacts to a species (e.g., 

injury, death, stress, or general habitat 

disturbance). Negative impacts to 

pygmy rabbits that have been caused by 

research activities have been few in 

number, occurred in limited areas, and 

occurred over short periods of time. We 

encourage research activities to 

continue in the future to increase our 

understanding of this species. With 

planning and care, adverse impacts of 

research activities can be minimized. 

Based on the best available information 

we find that research activities are not 

a significant threat now or in the 

foreseeable future, to the pygmy rabbit 

across its range. 

Disease epizootics in pygmy rabbits 

have not been reported within its range 

considered in this finding. Research is 

needed to determine if disease could be 

a threat in the future. Predation has 

been reported as the main cause of 

mortality in pygmy rabbits. Numerous 

species have been identified as 

predators of pygmy rabbits. Based on 

the best available information, we find 

that neither disease nor predation are 

significant threats now or in the 

foreseeable future, to the pygmy rabbit 

across its range. 

Based on our analysis of the existing 

regulatory mechanisms, we determined 

that States are managing pygmy rabbit 

hunting in three States while four others 

protect them hunting as species of 

concern or sensitive species. In 

Wyoming, many oil and gas projects 

will be reviewed and mitigation 

provided that may benefit pygmy 

rabbits. 

A large portion of pygmy rabbit 

habitat occurs on lands administered by 

Federal agencies and numerous policies, 

guidance, and laws have been 

developed to assist in managing these 

lands. We determined in the evaluation 

that other threats would not 

significantly affect the pygmy rabbit 

now or in the foreseeable future. Thus, 

we find the inadequacy of existing 

regulatory mechanisms is not a 

significant threat to the pygmy rabbit 

across its range now or in the 

foreseeable future. 

Other natural or manmade factors 

have occurred within the range of the 

pygmy rabbit, and these habitat impacts 

or actions will likely continue at some 

level in the future. As indicated above, 

intra- and inter-specific relationships 

between pygmy rabbits and among 

pygmy rabbits and other species are 

natural and occur across the range, but 

there is no indication that these 

relationships are negatively impacting 

the pygmy rabbit. Though impacts to 

pygmy rabbits have occurred related to 

stochastic events and vehicle collisions, 

they have been rarely reported. The best 

available information indicates that 

pygmy rabbit populations are not small 

or isolated across the range. Potential 

impacts due to climate change are 

general, and there is no demonstrated 

connection between climate change and 

reduced abundance or survival of 

pygmy rabbits. Recreational activities 

occur throughout the range of the 

pygmy rabbit, but there is no indication 

these activities are significantly 

impacting pygmy rabbit populations. 

The best available information indicates 

that the pygmy rabbit, as a habitat 

specialist, has not been limited across 

its range. 

During our status review for this 

species, it has become evident that 

many of the threat issues raised have 

been speculative and direct impacts to 

historical and extant pygmy rabbit 

populations have not been documented. 

Threats exist but do not appear to be 

significant across the range of the 

species. While the sagebrush ecosystem 

has been and will continue to be 

impacted by various natural and 

manmade events and activities in parts 

of the pygmy rabbit’s range, we have 

determined, based on the species’ 

current range and distribution, that 

pygmy rabbit populations continue to 

persist in much of its range, despite the 

numerous activities occurring within 

their habitat. Pygmy rabbits are 

represented across their current range 

which is not dissimilar from what is 

known of their historical distribution as 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60559 

discussed in the Distribution and Trend 

section. Our understanding of the 

pygmy rabbit’s range has improved, and 

the current known range has been 

extended in Montana, Nevada, and most 

notably Wyoming based on recent 

survey efforts. 

Based on our review of the best 

available scientific and commercial 

information, we find that the threats are 

not of sufficient imminence, intensity, 

or magnitude to indicate that the pygmy 

rabbit is in danger of extinction 

(endangered), or likely to become 

endangered within the foreseeable 

future (threatened) throughout its range. 

Therefore, listing the pygmy rabbit as an 

endangered or threatened species under 

the Act is not warranted at this time. 

Distinct Vertebrate Population Segment 

(DPS) 

After assessing whether the species is 

endangered or threatened throughout its 

range, we next consider whether any 

distinct vertebrate populations segment 

(DPS) exists and meets the definition of 

endangered or is likely to become 

endangered in the foreseeable future 

(threatened). 

Under the Service’s Policy Regarding 

the Recognition of Distinct Vertebrate 

Population Segments Under the 

Endangered Species Act (61 FR 4722, 

February 7, 1996), three elements are 

considered in the decision concerning 

the establishment and classification of a 

possible DPS. These are applied 

similarly for additions to or removal 

from the Federal List of Endangered and 

Threatened Wildlife. These elements 

include: 

(1) The discreteness of a population in 

relation to the remainder of the taxon to 

which it belongs; 

(2) The significance of the population 

segment to the taxon to which it 

belongs; and 

(3) The population segment’s 

conservation status in relation to the 

Act’s standards for listing, delisting 

(removal from the list), or 

reclassification (i.e., is the population 

segment endangered or threatened). 

In this analysis, we will evaluate 

whether pygmy rabbits in Mono County, 

California, meet the criteria to be 

considered a DPS. This analysis is being 

conducted because studies have 

indicated that pygmy rabbit populations 

in Mono County may be separated from 

the rest of the pygmy rabbit range 

(Grayson 2006, pp. 2969-2970; Larrucea 

and Brussard 2008a, pp. 694, 696). 

Discreteness 

Under the DPS policy, a population 

segment of a vertebrate taxon may be 

considered discrete if it satisfies either 

one of the following conditions: 

(1) It is markedly separated from other 

populations of the same taxon as a 

consequence of physical, physiological, 

ecological, or behavioral factors. 

Quantitative measures of genetic or 

morphological discontinuity may 

provide evidence of this separation. 

(2) It is delimited by international 

governmental boundaries within which 

differences in control of exploitation, 

management of habitat, conservation 

status, or regulatory mechanisms exist 

that are significant in light of section 

4(a)(1)(D) of the Act. 

We note that the standard set forth in 

the DPS policy is that a DPS be 

‘‘markedly separated’’ from other 

populations—thus, while absolute 

separation is not required, neither are 

‘‘large numbers’’ of individuals 

migrating between populations. Nor is 

absolute isolation required for 

populations to be markedly separated. 

Pygmy rabbits in Mono County appear 

to be markedly separated from other 

pygmy rabbit populations. The nearest 

known populations to Mono County 

populations are in western Nevada, 

approximately 100 mi (162 km) away 

(Larrucea and Brussard 2008a, p. 694). 

There are no known historical pygmy 

rabbit records for Lyon, Mineral, and 

Emeralda Counties, Nevada, which 

could provide possible connections 

between California and Nevada in this 

area. Surveys conducted during 2003 

and 2006 in Lyon and Mineral Counties 

did not find evidence of pygmy rabbits 

(Larrucea 2007, pp. 165-179). It is 

possible that the Mono County 

populations have been separated from 

the rest of the species’ range since the 

end of the Pleistocene (Grayson 2006, 

pp. 2969-2970). 

We determine, based on a review of 

the best available information, that the 

Mono County populations of pygmy 

rabbit are markedly separated from 

other pygmy rabbit populations as a 

consequence of physical factors and 

thus meet the discreteness criterion of 

the 1996 DPS policy. 

There are no international 

governmental boundaries associated 

with this species that are significant. 

The pygmy rabbit is found wholly 

within the United States. Because this 

element is not relevant in this case for 

a finding of discreteness, it was not 

considered in reaching this 

determination. 

Significance 

If a population segment is considered 

discrete under one or more of the 

conditions described in our DPS policy, 

its biological and ecological significance 

will be considered in light of 

Congressional guidance that the 

authority to list DPSs be used 

‘‘sparingly’’ while encouraging the 

conservation of genetic diversity. In 

making this determination, we consider 

available scientific evidence of the 

discrete populations segment’s 

importance to the taxon to which it 

belongs. Since precise circumstances are 

likely to vary considerably from case to 

case, the DPS policy does not describe 

all the classes of information that might 

be used in determining the biological 

and ecological importance of a discrete 

population. However, the DPS policy 

does provide four possible reasons why 

a discrete population may be significant. 

As specified in the DPS policy (61 FR 

4722), this consideration of the 

population segment’s significance may 

include, but is not limited to, the 

following: 

(1) Persistence of the discrete 

population segment in an ecological 

setting unusual or unique to the taxon; 

(2) Evidence that loss of the discrete 

population segment would result in a 

significant gap in the range of a taxon; 

(3) Evidence that the discrete 

population segment represents the only 

surviving natural occurrence of a taxon 

that may be more abundant elsewhere as 

an introduced population outside its 

historic range; or 

(4) Evidence that the discrete 

population segment differs markedly 

from other populations of the species in 

its genetic characteristics. 

A population segment needs to satisfy 

only one of these criteria to be 

considered significant. Furthermore, the 

list of criteria is not exhaustive; other 

criteria may be used as appropriate. 

(1) Persistence of the discrete 

population segment in an ecological 

setting unusual or unique to the taxon; 

The available information does not 

suggest that the ecological setting 

occupied by pygmy rabbits in the Mono 

County, California, portion of its range 

is unusual or unique when compared to 

the remainder of its range. The available 

information does not suggest that the 

vegetation, elevation, topography, or 

climate of the habitat occupied by the 

Mono County, California populations of 

the pygmy rabbit is unusual or unique 

to the taxon; nor is there any 

information indicating there are 

physiological or behavioral factors of 

the Mono County populations that are 

unusual or unique to the taxon. 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
60560 Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 

(2) Evidence that loss of the discrete 

population segment would result in a 

significant gap in the range of a taxon; 

The Mono County populations are 

located on the western periphery of the 

pygmy rabbit’s range. We have 

determined that they occupy less than 1 

percent of the species’ range. If the 

populations in Mono County were to be 

extirpated, the portion of the range lost 

would be small when compared to the 

remainder of the species’ range. Loss of 

these populations would not result in a 

gap in the pygmy rabbit’s range as they 

are located on the edge of the range and 

may not be providing connectivity to 

other portions of its range. Therefore, 

we conclude that loss of these 

populations would not be result in a 

significant gap in the range of the 

species. 

(3) Evidence that the discrete 

population segment represents the only 

surviving natural occurrence of a taxon 

that may be more abundant elsewhere 

as an introduced population outside its 

historic range; or 

The Mono County populations do not 

represent the only surviving natural 

occurrence of a taxon that may be more 

abundant elsewhere as an introduced 

population outside its historic range. 

The pygmy rabbit’s current distribution 

is similar to its historic distribution, and 

the species has not been introduced to 

areas outside of its historic range. The 

Mono county populations represent a 

small portion of the total extent of the 

species’ range. 

(4) Evidence that the discrete 

population segment differs markedly 

from other populations of the species in 

its genetic characteristics. 

As indicated above, pygmy rabbits in 

Mono County have not been genetically 

tested. Therefore, there is no 

information to indicate that these 

populations differ markedly from other 

populations of this species in its genetic 

characteristics. 

We therefore conclude that pygmy 

rabbit populations in Mono County do 

not meet the significance element of the 

Service’s DPS policy because they do 

not occur in an ecological setting 

unusual or unique to the taxon; their 

loss would not result in a significant gap 

in the range of the taxon; they do not 

represent the only surviving natural 

occurrence of the taxon; and there is no 

evidence available indicating that Mono 

County populations differ markedly in 

genetic characteristics. 

Conclusion of Distinct Population 

Segment Review 

Based on the best scientific and 

commercial information available, we 

find that pygmy rabbit populations 

found in Mono County, California, meet 

the discreteness element of our DPS 

policy but fail to meet the significance 

element of that policy. Since both 

discreteness and significance are 

required to satisfy the DPS policy, we 

have determined that Mono County 

pygmy rabbit populations do not qualify 

as a DPS under our policy. As a result, 

no further analysis under the DPS 

policy is necessary. 

Significant Portion of the Range 

Analysis 

Having determined that the pygmy 

rabbit is not endangered or threatened 

throughout all its range, we must next 

consider whether there are any 

significant portions of the range where 

the pygmy rabbit is in danger of 

extinction or is likely to become 

endangered in the foreseeable future. 

To identify those portions that may be 

significant portions of the range, we 

determine whether there is substantial 

information indicating that: (i) The 

portions may be significant, and (ii) 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 be a 

significant portion of the range. 

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 be significant portions 

of the range. 

If we identify any significant portions, 

we then determine whether the species 

is threatened or endangered in that 

portion of the range. Depending on the 

biology of the species, its range, and the 

threats it faces, the Service may address 

either the significance question or the 

status question first. Thus, if the Service 

considers significance first and 

determines that a portion of the range is 

not significant, the Service need not 

determine whether the species is 

threatened or endangered there. 

Likewise, if the Service considers status 

first and determines that the species is 

not threatened or endangered in a 

portion of its range, the Service need not 

determine if that portion is significant. 

Based on our review of survey 

information, distributional data, and 

potential threats, we have determined 

that the pygmy rabbit range in Oregon, 

Idaho, Montana, Nevada, and Utah does 

not warrant further consideration to 

determine if it is a significant portion of 

the range that is threatened or 

endangered. We found no areas within 

this portion of the range where threats 

are geographically concentrated. The 

potential factors that may affect the 

species are essentially uniform 

throughout this portion of the range. 

However, we did determine that the 

Mono County, California, and the 

Wyoming portions of the pygmy rabbit’s 

range warranted further consideration to 

determine if they are significant 

portions of the range that are threatened 

or endangered. The Mono County, 

California portion was selected due to 

the possible lack of connectivity to 

populations in Nevada, and therefore, 

threats to it may include population 

isolation. Regardless of the possible 

extirpation of pygmy rabbit populations 

in Modoc and Lassen Counties, 

California (Larrucea and Brussard 

2008a, pp. 694, 696), populations in 

Mono County may be isolated from the 

rest of the range. There are no known 

historical pygmy rabbit records for 

Lyon, Mineral, and Emeralda Counties, 

Nevada, which could provide possible 

connections between California and 

Nevada in this area. Surveys conducted 

during 2003 and 2006 in Lyon and 

Mineral Counties did not find evidence 

of pygmy rabbits (Larrucea 2007, pp. 

165-179). It is possible that the Mono 

County populations have been separated 

from the rest of the range since the end 

of the Pleistocene (Grayson 2006, pp. 

2969-2970) (see our discussion 

regarding DPS above). The Wyoming 

portion was selected due to the 

concentration of energy exploration and 

development in the southwestern and 

south central areas of the State and the 

possible threat from these activities to 

pygmy rabbit populations in those areas. 

To assess the significance of these 

portions of the range, we evaluated 

whether these two areas occupy 

relatively large or particularly highquality, unique habitat that could be 

affected, or if their locations or 

characteristics make them less 

susceptible to certain threats than other 

portions of the species’ range such that 

they could provide important 

population refugia in the event of 

extirpations elsewhere in the species’ 

range. We determined that the Mono 

County populations occupy less than 1 

percent of the species range, and the 

available information does not suggest 

that the habitat occupied by pygmy 

rabbits in this portion is particularly 

high quality or unique when compared 

to the remainder of the range. The 

pygmy rabbit, in addition to Mono 

County California, occurs in sagebrush 

habitats located in southeastern Oregon, 

southern Idaho, southwestern Montana, 


jdjones on DSK8KYBLC1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 189 / Thursday, September 30, 2010 / Proposed Rules 60561 

western Utah, and northern and eastern 

Nevada. We did not find that the Mono 

County populations are less susceptible 

to certain threats than other portions of 

the range. We also evaluated the 

historical value of this portion and how 

frequently it is used by the species and 

whether the portion contains important 

concentrations of certain types of 

habitat that are necessary for the species 

to carry out its life-history functions, 

such as breeding, feeding, migration, 

dispersal, or wintering. We found that 

the Mono County populations are not 

significant because the habitats 

necessary for breeding, feeding, 

dispersal, or wintering are utilized year 

round and are found throughout the 

pygmy rabbit’s range. These necessary 

habitats are not concentrated in Mono 

County. 

We determined that the Wyoming 

populations occupy about 11.5 percent 

of the species’ range, and available 

information does not suggest that the 

habitat occupied by pygmy rabbits in 

this portion is particularly high quality 

or unique when compared to the 

remainder of the range. The pygmy 

rabbit, in addition to Wyoming, occurs 

in sagebrush habitats located in 

southeastern Oregon, southern Idaho, 

southwestern Montana, western Utah, 

and northern and eastern Nevada. We 

did not find that the Wyoming 

populations are less susceptible to 

certain threats than other portions of the 

range. We also evaluated the historical 

value of this portion of the range and 

how frequently it is used by the species 

and whether the portion contains 

important concentrations of certain 

types of habitat that are necessary for 

the species to carry out its life-history 

functions, such as breeding, feeding, 

migration, dispersal, or wintering. We 

found that the Wyoming populations are 

not significant because the habitats 

necessary for breeding, feeding, 

dispersal, or wintering are utilized year 

round and are found throughout the 

pygmy rabbit’s range. These necessary 

habitats are not concentrated in 

Wyoming. 

Based on the discussion above, we 

determined that the Mono County, 

California, and the Wyoming portions of 

the current range of the pygmy rabbit 

are not significant to the species and 

therefore do not warrant further 

consideration to determine if they are a 

significant portion of the range that is 

threatened or endangered. 

We do not find that the pygmy rabbit 

is in danger of extinction now, nor is it 

likely to become endangered within the 

foreseeable future throughout all or a 

significant portion of its range. 

Therefore, listing the pygmy rabbit as 

threatened or endangered under the Act 

is not warranted throughout all or a 

significant portion of its range at this 

time. 

We request that you submit any new 

information concerning the status of, or 

threats to, the pygmy rabbit to our 

Nevada Fish and Wildlife Office (see 

ADDRESSES section) whenever it 

becomes available. New information 

will help us monitor the pygmy rabbit 

and encourage its conservation. If an 

emergency situation develops for the 

pygmy rabbit, we will act to provide 

immediate protection. 

References Cited 

A complete list of references cited is 

available on the Internet at http:// 

www.regulations.gov and upon request 

from the Nevada Fish and Wildlife 

Office (see ADDRESSES). 

Authors 

The primary authors of this document 

are the staff members of the Nevada Fish 

and Wildlife Office, U.S. Fish and 

Wildlife Service, Reno, Nevada. 

Authority 

The authority for this action is section 

4 of the Endangered Species Act of 

1973, as amended (16 U.S.C. 1531 et 

seq.). 

Dated: September 20, 2010 

Rowan Gould, 

Acting Director, Fish and Wildlife Service. 

[FR Doc. 2010–24349 Filed 9–29–10; 8:45 am] 

BILLING CODE 4310–55–S 


jdjones on DSK8KYBLC1PROD with PROPOSALS2