[Federal Register: November 9, 2004 (Volume 69, Number 216)]
[Proposed Rules]               
[Page 64889-64901]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

50 CFR Part 17

Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List the White-Tailed Prairie Dog as Threatened or 

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.


SUMMARY: We, the U.S. Fish and Wildlife Service (USFWS), announce a 90-
day finding on a petition to list the white-tailed prairie dog (Cynomys 
leucurus) as threatened or endangered under the Endangered Species Act 
of 1973, as amended. We find the petition and other information 
available do not provide substantial scientific or commercial 
information indicating that listing this species may be warranted. 
Therefore, we will not be initiating a further status review in 
response to this petition. We ask the public to submit to us any new 
information that becomes available concerning the status of the species 
or threats to it. This will help us monitor and encourage the 
conservation of the species.

DATES: The finding announced in this document was made on November 2, 
2004. You may submit new information concerning this species for our 
consideration at any time.

ADDRESSES: The complete file for this finding is available for 
inspection during normal business hours at the Utah Ecological Services 
Field Office, U.S. Fish and Wildlife Service, 2369 West Orton Circle, 
Suite 50, West Valley City, Utah 84119. Submit new information, 
materials, comments or questions concerning this taxon to the Service 
at the above address.

FOR FURTHER INFORMATION CONTACT: Henry Maddux, Field Supervisor, at the 
address given in the ADDRESSES section or telephone 801-975-3330 or 
facsimile 801-975-3331.



    Section 4(b)(3)(A) of the Endangered Species Act (ESA) of 1973, as 
amended (16 U.S.C. 1531 et seq.), requires that we make a finding on 
whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information indicating that

[[Page 64890]]

the requested action may be warranted. We are to base this finding on 
information provided in the petition, and all other information 
available to us at the time the finding was made. Our standard for 
substantial information with regard to a 90-day petition finding is 
``that amount of information that would lead a reasonable person to 
believe that the measure proposed in the petition may be warranted'' 
(50 CFR 424.14(b)). When a substantial determination is made, we are 
required to promptly begin a review of the status of the species, if 
one is not already initiated.
    On July 15, 2002, we received a formal petition to list the white-
tailed prairie dog (Cynomys leucurus) as threatened or endangered, in 
accordance with provisions in section 4 of the ESA. The petition was 
filed by the Center for Native Ecosystems, Biodiversity Conservation 
Alliance, Southern Utah Wilderness Alliance, American Lands Alliance, 
Forest Guardians, the Ecology Center, Sinapu, and Terry Tempest 
    On August 27, 2002, we acknowledged receipt of the petition and 
advised the petitioners we would not be able to process the petition in 
a timely manner. On November 29, 2002, we received a notice of intent 
to sue from the petitioners concerning our failure to produce a 90-day 
finding on the subject petition in accordance with the provisions of 
section 4 of the ESA. We responded on February 11, 2003, reiterating 
that we would not be able to begin an evaluation of the white-tailed 
prairie dog petition until work on the higher priority activities was 
completed. On February 20, 2003, the petitioners filed a complaint to 
compel the USFWS to make a 90-day finding. This 90-day petition finding 
is made in accordance with a settlement agreement that requires us to 
complete a finding on the petition to list the white-tailed prairie dog 
by October 31, 2004 [Center for Native Ecosystems, et al. v. Norton et 
al. (cv-03-31-M (DWM))].
    The contents of this finding summarize that information included in 
the petition (cited as Center for Native Ecosystems 2002) and other 
information readily available to us in our files at the time of the 
petition review. Most notable of the other information we used in our 
review was the multi-state White-Tailed Prairie Dog Conservation 
Assessment (Conservation Assessment) (cited as Seglund et al. 2004). 
Beginning in 2003, the White-Tailed Prairie Dog Working Group of the 
State Prairie Dog Conservation Team began work on a species assessment. 
The Draft Conservation Assessment was released May 19, 2004, and the 
final Conservation Assessment was released August 31, 2004. While our 
determination is based on the contents of the petition submitted we 
also included in our review the information in the Conservation 
Assessment. Because it was not practicable to respond to the petition 
for approximately 2 years, we considered the information in the 
Conservation Assessment in order to ensure that the best available 
information was used in our review. Our review for the purposes of a 
so-called ``90-day'' finding under section 4(b)(3)(A) of the ESA and 
section 424.14(b) of our regulations is limited to a determination of 
whether the information in the petition meets the ``substantial 
scientific or commercial information'' threshold. In the case of the 
white-tailed prairie dog, had the petition not met the ``substantial 
scientific or commercial information'' standard, but the Conservation 
Assessment had included substantial information, we would have used 
that information to make a positive 90-day finding. We do not conduct 
additional research at this stage of the process, but we do critically 
review the petition as to the scientific validity of the information 
presented therein. As the ESA and regulations contemplate, at the 90-
day finding we base our finding on the petitioner's information and on 
other information readily available to us in our files at the time of 
the petition review. Our determination is whether this information is 
scientific and substantial.

Biology and Distribution


    Prairie dogs are in the squirrel family, Sciuridae, and are endemic 
to North America (Hollister 1916; Hoogland 2003; Seglund et al. 2004). 
The white-tailed prairie dog is one of five prairie dog species that 
inhabit western North America. Prairie dogs belong to the genus Cynomys 
(Hollister 1916). The genus has been split into two subgenera (Clark et 
al. 1971, Pizzimenti 1975). Utah (Cynomys parvidens), Gunnison (Cynomys 
gunnisoni), and white-tailed prairie dogs are the three species that 
make up the subgenus Leucocrossuromys (Hollister 1916, Clark et al. 
1971). Although Burt and Grossenheimer (1964 as cited in Knowles 2002) 
considered all members of the subgenus Leucocrossuromys to be a single 
species, based on Pizzimenti's (1975) work, it is doubtful that the 
single species concept for the subgenus Leucocrossuromys is valid 
(Knowles 2002). According to Knowles (2002), there is sufficient 
genetic and morphological evidence to conclude that there are three 
separate species within the white-tailed prairie dog subgenera. The 
subgenus Cynomys includes black-tailed (Cynomys ludovicianus) and 
Mexican prairie dogs (Cynomys mexicanus). The Leucocrossuromys subgenus 
prairie dogs have short tails with white tips and have weaker social 
structures than the Cynomys subgenus (Pizzimenti 1975).

Species Description

    The white-tailed prairie dog is the largest member of the subgenera 
Leucocrossuromys, and is only slightly smaller than black-tailed and 
Mexican prairie dogs (Clark et al. 1971). They are between 315-400 
millimeters (mm) (12.4-16.7 inches (in)) in length with a tail length 
of 40-65 mm (1.6-2.6 in) and weigh between 650-1,700 grams (g) (23-60 
ounces (oz)) (Fitzgerald et al. 1994). The tail has a grayish white tip 
and is white on the entire terminal half (Merriam 1890, Fitzgerald et 
al. 1994). The coat is generally gray (Hollister 1916). They have 
distinctive dark brown or black cheek patches that extend above the eye 
with a lighter black stripe that extends below the eye onto the cheek 
(Fitzgerald et al. 1994). Male white-tailed prairie dogs are on average 
larger than females (Fitzgerald et al. 1994).

Ecology and Life History

    Unlike black-tailed prairie dogs that live in grass-dominated 
habitats, white-tailed prairie dogs are found in drier landscapes 
including shrublands, semi-desert grasslands, and mountain valleys 
(Tileston and Lechleitner 1966; Clark 1977; Collins and Lichvar 1986; 
Fitzgerald et al. 1994; Gadd 2000). Like other prairie dog species, 
white-tailed prairie dogs rely on good visibility to enable them to see 
predators; however, they do not clip taller vegetation like black-
tailed prairie dogs (Clark 1977). White-tailed prairie dogs occur at 
elevations ranging from 1,150 to 3,200 meters (m) (3,800 to 10,500 feet 
(ft)) (Tileston and Lechleitner 1966). Their habitats are generally on 
low slopes or level ground (Forrest et al. 1985, Collins and Lichvar 
    All prairie dogs are primarily herbivorous, and mainly forage on 
grasses and forbs (Stockard 1929, Kelso 1939). Although prairie dogs 
prefer forbs, they will consume other plants seasonally; for example, 
prairie dogs browse upon sagebrush and saltbush during early spring, 
grasses in summer, and seed heads following grass and sedge flowering 
(Kelso 1939, Tileston and Lechleitner 1966). Prairie dogs

[[Page 64891]]

obtain most of their water requirements through vegetation, and may 
become water-stressed if sufficient succulent vegetation is unavailable 
(Stockard 1929, Seglund et al. 2004).
    White-tailed prairie dogs breed once a year and have a single 
litter averaging four to five pups (Hoogland 2001). They can reproduce 
at 1 year of age (Cooke 1993). Breeding occurs from late March to mid-
April (Tileston and Lechleitner 1966). Pups are born in the burrows 
after a gestation period of approximately 30 days (Tileston and 
Lechleitner 1966), and emerge for the first time 4 to 6 weeks after 
birth (Bakko and Brown 1967). Reproductive success ranges from 30 to 60 
percent (Tileston and Lechleitner 1966, Bakko and Brown 1967, Menkens 
and Anderson 1989).
    Animal densities within white-tailed prairie dog colonies are 
significantly lower than in black-tailed prairie dog colonies (Eskey 
and Haas 1940; Tileston and Lechleitner 1966; Hoogland 1981; Clark et 
al. 1985). In white-tailed prairie dog colonies surveyed for black-
footed ferret (Mustela nigripes) recovery, Biggins et al. (1993) 
reported a density range of 5.7-16.1 prairie dogs per hectare (ha) 
(2.3-6.5 prairie dogs per acre (ac)). Surveys of other white-tailed 
prairie dog colonies reported densities ranging between 0.7 and 7.9 
prairie dogs per ha (0.3-3.2 prairie dogs per ac) (Tileston and 
Lechleitner 1966, Clark 1977). In comparison, black-tailed prairie dog 
densities vary depending upon the season, region, and climatic 
conditions, but typically are higher and range from 5 to 45 individuals 
per ha (2 to 18 individuals per ac) (Fagerstone and Ramey 1996, 
Hoogland 1995, King 1955, Koford 1958, and Miller et al. 1996, as cited 
in 69 FR 51218).
    Prairie dogs are semi-fossorial (or adapted for digging) and 
construct their own burrow systems. Burrow systems can be extensive, 
with numerous entrances. The density of burrows varies based on the 
food resources available (Clark 1977). All prairie dog species are 
social and rely on a social structure for survival. Therefore, burrow 
systems are grouped together (Clark 1977). Burrow systems within one 
male's territory makes up a coterie (Hoogland 1995). A concentration of 
prairie dogs with a minimum of 20 burrows per ha (8 burrows per ac) on 
at least 5 ha (12 ac) comprises a colony (Seglund et al. 2004). 
Determining what constitutes the boundary of a white-tailed prairie dog 
colony is particularly difficult because white-tailed prairie dogs are 
more sparsely distributed than black-tailed prairie dogs (Seglund et 
al. 2004).
    The definition of a complex and subcomplex has been defined in 
terms of black-footed ferret dispersal capabilities. It is unclear if 
these definitions are entirely adequate for white-tailed prairie dogs. 
A complex is a group of prairie dog colonies between which individual 
black-footed ferrets can migrate between them commonly and frequently. 
Colonies within a complex are separated from the nearest colony by no 
more than 7 kilometers (km) (4 miles (mi)), with no impassable barriers 
between the colonies (Seglund et al. 2004). A subcomplex is defined as 
an aggregation of colonies separated from the nearest adjacent group by 
no more than 7 km (4 mi), but due to various non-biological factors 
(e.g., State boundaries, land ownership) the whole complex is not 
surveyed and management occurs on only a portion of the entire complex 
(Seglund et al. 2004).
    White-tailed prairie dogs are active approximately 5 to 7 months 
per year, from early spring to fall (Clark 1977, Cooke 1993). Unlike 
black-tailed prairie dogs, white-tailed prairie dogs are obligate 
hibernators (Harlow and Menkens 1986, Harlow and Braun 1995). They 
hibernate in late fall and winter (Cooke 1993). The amount of time 
spent hibernating is determined by availability of food resources 
(Clark 1977). In warm weather, even in mid-winter, if grasses are 
growing, white-tailed prairie dogs have been observed feeding 
(Hollister 1916, Goodrich and Buskirk 1998).

Distribution, Abundance, and Trends

    White-tailed prairie dogs' distribution ranges across four States--
Wyoming, Colorado, Utah, and Montana (Knowles 2002). According to 
Knowles (2002), the range of white-tailed prairie dogs has not changed 
appreciably from the historical range. There are indications that 
abundance may have declined as a result of past control efforts and 
plague. However, historical abundance and distribution are not well 
documented for white-tailed prairie dogs (Seglund et al. 2004). In 
addition, white-tailed prairie dog surveys have used varying 
methodologies, have not always clearly specified occupied or unoccupied 
habitats, and have been conducted in areas of varying size (Seglund et 
al. 2004).
    Accurate, comprehensive inventories of currently occupied white-
tailed prairie dog habitat in each State are not available. The 
petitioners use a Gap Analysis predictive model to estimate 17,719,220 
ha (43,785,146 ac) of historically suitable habitat range wide. The 
petition estimates currently occupied habitat at 325,526 ha (804,392 
ac). The Conservation Assessment estimates the historical range of the 
white-tailed prairie dogs was 20,224,807 ha (49,974,813 ac). The 
Conservation Assessment estimates there are 340,470 ha (841,300 ac) of 
currently occupied habitat.
    Neither the petition nor the Conservation Assessment provides a 
population estimate for white-tailed prairie dogs. Developing a 
reliable population estimate for white-tailed prairie dogs is 
complicated by the lack of accurate range-wide estimates of occupied 
acreage and limited density data.
    Most of the multi-year white-tailed prairie dog data available is 
for large complexes that have been considered and monitored for black-
footed ferret reintroduction. Other data exist throughout the range of 
the species, but they are limited to a single data point. Data on these 
larger complexes were collected in conjunction with black-footed ferret 
reintroduction efforts. The large white-tailed prairie dog complexes 
that were considered suitable as black-footed ferret habitat have been 
mapped and monitored. Because the data were collected for the purpose 
of determining habitat suitability for black-footed ferret 
reintroduction, we do not have specific population or trend information 
for smaller colonies and complexes across the species range. Where 
population estimates are not available, smaller colonies or complexes 
are described only by their presence and general location.
    Concerns exist regarding the efficacy of using black-footed ferret 
survey data to evaluate the status of white-tailed prairie dog 
populations due to the questionable correlation between counts of 
active burrows and densities of animals (Menkens 1987, Severson and 
Plumb 1998, Powell et al. 1994). Estimates of occupied habitat are 
similarly complicated in part due to white-tailed prairie dog behavior. 
Burrow densities and activity levels are variable throughout a colony 
and mapping efforts have thus often utilized topographic features to 
describe colony and complex boundaries (Seglund et al. 2004).
    The Conservation Assessment attempted to alleviate sampling and 
data recording deficiencies by (1) presenting data state-by-state 
rather than portraying range-wide population trends, (2) only providing 
prairie-dog population information on black-footed ferret 
reintroduction sites surveyed for three or more years, and (3) only 
providing population information on areas greater than 1,500 ha (3,706 
ac). Coeffecients of variation and standard deviations were calculated 
to evaluate population

[[Page 64892]]

estimate variability (Seglund et al. 2004).
    Inventory information on colonies and trends (if determinable) are 
detailed here by State. Table 1 lists those colonies with at least 3 
years of monitoring data, consistent with information presented by the 
Conservation Assessment. Other, smaller colonies are identified and 
described in the text.

                     Table 1.--Population Estimates for White-Tailed Prairie Dog Complexes Monitored for Consideration as Possible Black-Footed Ferret Re-Introduction Sites
                                                                 [Data taken from Conservation Assessment, Seglund et al. 2004]
                     State and colony                        1988     1989     1991     1992     1993     1994     1995     1996     1997     1998     1999     2000     2001     2002     2003
  Shirley Basin..........................................  .......  .......   30,389   29,828   14,551    5,916    7,564   19,876   10,343    6,547    7,161    6,669   34,698  .......  .......
  Meeteetse..............................................   25,494   17,692  .......  .......    1,299  .......  .......  .......    7,095  .......  .......    1,066  .......  .......  .......
  Coyote Basin...........................................  .......  .......  .......  .......  .......  .......  .......  .......    3,132  .......    5,509    6,666    3,545    3,677    1,055
  Wolf Creek--West.......................................  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......   19,719  .......    7,266    9,214
  Wolf Creek--East.......................................  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......   10,331    8,212   10,754
  Coyote Basin...........................................  .......  .......  .......  .......  .......  .......  .......  .......   43,205   39,565   38,180   33,438   37,424   54,444   14,031
  Kennedy Wash...........................................  .......  .......  .......  .......  .......  .......  .......  .......  .......   10,697    6,411    5,725    3,670   10,282    3,313
  Shiner Basin...........................................  .......  .......  .......  .......  .......  .......  .......  .......   15,065   47,551    5,383   13,707  .......  .......  .......
  Snake John.............................................  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......  .......   49,346   50,437   31,118

    In Wyoming, white-tailed prairie dogs are found in Big Horn, Park, 
Hot Springs, Natrona, Fremont, Sublette, Sweetwater, Lincoln, Uinta, 
Carbon, and Albany Counties (Seglund et al. 2004). The Conservation 
Assessment provides population information for three complexes: 
Meeteetse, Shirley Basin, and Kinney Rim. There are an additional 26 
colonies identified by the Conservation Assessment and the Petition for 
which population numbers or trend information are not provided. The 
Meeteetse Complex, in Park County, declined from an estimated 80,000 ha 
(200,000 ac) in 1915, to 4,900 ha (12,000 ac) of prairie dogs in 1981 
when the last known wild black-footed ferrets were discovered there, to 
about 3,000 ha (7,000 ac) in 1986, to about 200 ha (500 ac) by 2000 
(Knowles 2002). Population declines between 1915 and 1981 were 
probably, primarily, the result of intensive federal control efforts. 
Recent population declines at Meeteetse are probably the result of 
plague which first appeared in this complex in the mid-1980s (Biggins 
2003, Seglund et al. 2004. Surveys in the Shirley Basin Complex, Carbon 
County, indicated large annual fluctuations of occupied habitat 
attributed to plague since 1991 (Seglund et al. 2004). From a high in 
1991, the population declined approximately 78 percent by 1997 and 
1999, but recent estimates indicate that the population has recovered 
to levels similar to 1991 numbers and densities. Number of colonies has 
doubled and occupied habitat has increased 50 percent since 1990 
(Seglund et al. 2004). Accurate population trends and occupied habitat 
data are unavailable for the Kinney Rim Complex, in Sweetwater County. 
Plague apparently reduced population densities in 1989; prairie dogs 
still occupied the complex by 1993 (Conway 1989 and Albee 1993, as 
cited in Seglund et al. 2004). The petition cites personal 
communications from B. Luce (2001) documenting substantial declines at 
this complex by 1995. No more recent specific data are reported. For 
other complexes in the State, we only have single-year estimates for 
complex size and, thus, no ability to assess trends.
    In Colorado, the range of the white-tailed prairie dog includes 
Moffat, Routt, Rio Blanco, Garfield, Mesa, Delta, Montrose, Eagle, 
Jackson, Ouray, and Larimer Counties (Seglund et al. 2004). The 
Conservation Assessment provides population information for three 
complexes: Little Snake, Wolf Creek, and Coyote Basin. Colonies also 
occur in 11 other counties or Bureau of Land Management (BLM) Resource 
Areas across Colorado for which population numbers or trend information 
are not provided. The Little Snake Complex, in Moffat County, 
encompassed 31,700 ha (78,300 ac) in 1989 (USFWS et al. 1995). In 1994, 
dramatic declines occurred at the same time plague-positive fleas were 
detected in the area (USFWS et al. 1995, Seglund et al. 2004). 
Inventories conducted on a portion of the Little Snake Complex in 1999 
indicated a 90 percent decline since 1990 surveys (Seglund et al. 
2004). Surveys in 2002 and 2003 indicated little if any change in 
prairie dog populations and drought conditions resulted in extensive 
vegetation losses which may have contributed to slow population 
recovery (Seglund et al. 2004). The Wolf Creek Complex, in Moffat and 
Rio Blanco Counties, was first mapped by Gilbert in 1976. Plague 
resulted in over 75 percent declines in this complex and other areas of 
the White River BLM Resource area in the mid-1980's (CDOW 1986, Seglund 
et al. 2004). Populations across the White River Resource area, 
including Wolf Creek, rebounded and approached pre-plague numbers by 
1994 (Seglund et al. 2004). Surveys from 2000 through 2003 show 
relatively stable prairie dog populations on the east side of Wolf 
Creek and a 50 percent decline on the west side of Wolf Creek (Seglund 
et al. 2004). The Coyote Basin Management Area, straddling the Utah-
Colorado border, fluctuated from 3,132 white-tailed prairie dogs in 
1997 to 6,666 prairie dogs in 2000 to 1,055 prairie dogs in 2003 
(Seglund et al. 2004); the 2003 figures represent a 65 percent decline 
from 1997 levels and an 84 percent decline from the high observed in 
    In Utah, white-tailed prairie dogs occur in Rich, Summit, Daggett, 
Uintah, Duchesne, Carbon, Emery, and Grand Counties (Seglund et al. 
2004). The Conservation Assessment provides population information for 
five complexes: Coyote Basin, Kennedy Wash, Shiner Basin, Snake John, 
and Cisco Desert. There are an additional 15 colonies or areas that are 
identified as containing white-tailed prairie dog habitats, however, 
these areas have not been inventoried and there is no population trend 
information (Seglund et al. 2004). The Cisco Complex, in Grand County, 
has not been inventoried with consistent sampling techniques, however 
declines and low activity levels have been consistently reported since 
1991 (Seglund et al. 2004). The Coyote Basin Subcomplex was first 
mapped in 1985 (Seglund et al. 2004). Prairie dog populations appeared 
relatively stable from 1997 through 2002 (Seglund et al. 2004). A high 
population estimate of 54,444 prairie dogs was

[[Page 64893]]

reported in 2002 with a subsequent 75 percent decline observed in 2003 
(Seglund et al. 2004). Kennedy Wash Subcomplex surveys show a similar 
pattern. Prairie dog population estimates were reported to be a high of 
10,000 animals in 1998 and again in 2002 with downward trends of 50 to 
60 percent during interim years (Seglund et al. 2004). The Shiner 
Subcomplex declined by 44 percent between 1998 and 2000 and has 
continued to support only low density prairie dog populations (Seglund 
et al. 2004). The Snake John Subcomplex maintained highs of 
approximately 50,000 prairie dogs in 2001 and 2002, followed by a 38 
percent decline in 2003; however, only 3 years of data are available, 
so long term trends are unknown (Seglund et al. 2004).
    In Montana, white-tailed prairie dogs currently occur in Carbon 
County in the Clark Fork Valley (Seglund et al. 2004). Between 1975 and 
1977, Flath (1979) identified 15 white-tailed prairie dog colonies in 
the State. In 1997, Flath revisited the 15 colonies and found only 2 
remaining, but 4 new colonies were also identified (Montana Prairie Dog 
Working Group 2002, as cited in Seglund et al. 2004). The petitioners 
listed the following white-tailed prairie dog colonies as having been 
extirpated--West Fork, Wolf Creek, Chance, Bridger, Warren colonies No. 
7 and No. 8, Bear Canyon colonies No. 9, No. 10, and No. 11, Gypsum 
Creek colonies No. 12 and No. 13, Silver Tip Creek, and Hunt Creek (D. 
Flath, Montana Fish, Wildlife, and Parks, pers. comm., as cited in 
Center for Native Ecosystems 2002). The petition asserts that these 
colonies have been extirpated for a variety of reasons including: 
plague (Warren colonies No. 7 and No. 8, Bear Canyon colonies No. 9, 
No. 10, and No. 11, and Gypsum Creek colonies No. 12 and No. 13), 
poisoning (Bridger), urban development (West Fork), and conversion to 
agriculture (Wolf Creek, Chance, Silver Tip Creek, and Hunt Creek) (D. 
Flath, pers. comm., as cited in Center for Native Ecosystems 2002. 
Although Montana represents the northern edge of the white-tailed 
prairie dog's range and totals less than 1 percent of the predicted 
range of the species (Seglund et al. 2004), colonies in Montana provide 
insights into the possible effects of human-caused factors and disease 
on small populations. That said, there is no indication that trends in 
Montana are representative of small colony trends range-wide. Occupied 
habitat is estimated at 48 ha (119 ac) within six colonies, a decline 
of 85 percent from the high of 280 ha (692 ac) within fifteen colonies 
in 1979.

                Table 2.--Montana White-Tailed Prairie Dog (WTPD) Occupied Acreage Data by Colony
                                                                              Colony size ha     Colony size ha
                             State and colony                                 (ac) 1975-1977     (ac) 1999-2003
    1.....................................................................         2-4 (5-10)  .................
    2.....................................................................          0.8 (2.0)  .................
    3 (Chance Bridge).....................................................      30-34 (74-84)           5.1 (12)
    4.....................................................................             8 (20)  .................
    5 (Robertson Draw)....................................................          100 (250)        16.4 (40.5)
    6.....................................................................              1 (2)  .................
    7.....................................................................      28-40 (69-99)  .................
    8.....................................................................        4-8 (10-20)  .................
    9.....................................................................            32 (79)  .................
    10....................................................................      20-32 (50-79)  .................
    11....................................................................      16-24 (40-59)  .................
    12....................................................................       8-20 (20-49)  .................
    13....................................................................              1 (2)  .................
    14....................................................................        0.4-1 (1-2)  .................
    15....................................................................         1-4 (2-10)  .................
    Duplex................................................................  .................           9.1 (22)
    S. Sage Creek.........................................................  .................           5.9 (15)
    Warren................................................................  .................           7.5 (19)
    Inferno Creek.........................................................  .................           4.2 (10)
      Total...............................................................      \1\ 280 (690)       \1\ 48 (120)
\1\ May not add due to rounding.
Source: Seglund et al. 2004.

    It should be noted that some level of natural fluctuation in 
population size, occupied acreage, and density is expected. Some white-
tailed prairie dog populations have been reported to fluctuate by more 
than 50 percent between consecutive years (Menkens and Anderson 1989, 
as cited in Seglund et al. 2004). Variation in densities between years 
and also among habitats is likely driven partly by local ecology such 
as site-specific topography, soil type, climate and vegetation quantity 
and quality. The Conservation Assessment notes that the reason some 
colonies rebound quickly and others never recover completely are poorly 
understood. Disease, especially the introduced pathogen responsible for 
sylvatic plague (Yersinia pestis), may play a role in ``amplifying 
population fluctuations'' (Menkens 1987, Forrest et al. 1988, Seglund 
et al. 2004).
    Historically, white-tailed prairie dog populations were probably 
not static, but researchers have inferred that it is unlikely that 
populations fluctuated as dramatically as they do today (Seglund et al. 
2004). However neither the petition nor the Conservation Assessment 
provide substantial scientific information on this inference specific 
to white-tailed prairie dogs. Observations of black-tailed prairie dogs 
provide some evidence that prairie dog populations may not have 
fluctuated historically to the extent that they do today. Biggins and 
Kosoy (2001) analyzed the role of the black-footed ferret and its 
relationship with prairie dogs. For example, plague has never been 
detected within black-tailed prairie dog colonies at Wind Cave National 
Park, South Dakota, and the population exhibits relatively stable 
yearly population levels (Hoogland 1995). This differs from a 
population at the Rocky Mountain Arsenal National Wildlife

[[Page 64894]]

Refuge near Denver, Colorado where epizootics of plague are frequent 
and extreme population fluctuations are common (Biggins and Kosoy 
2001). White-tailed prairie dogs lack a comparable example because 
there are no plague free portions of their range.

Conservation Status

    Pursuant to section 4(a) of the ESA, we may list a species of any 
vertebrate taxon on the basis of any one of the following factors--(A) 
present or threatened destruction, modification, or curtailment of 
habitat or range; (B) overutilization for commercial, recreational, 
scientific, or educational purposes; (C) disease or predation; (D) 
inadequacy of existing regulatory mechanisms; or (E) other manmade or 
natural factors affecting its continued existence. The petition asserts 
that the range of white-tailed prairie dog populations has been 
negatively affected by plague; recreational shooting; poisoning; oil, 
gas, and mineral extraction; conversion of habitat to agricultural use; 
urbanization; fire suppression; overgrazing; noxious weeds; drought; 
and climate change. Oil, gas, and mineral extraction, conversion of 
habitat to agricultural use, urbanization, overgrazing, fire 
suppression and the spread of noxious weeds are discussed under factor 
A. Recreational shooting is discussed under factor B. Plague is 
discussed under factor C. The adequacy or inadequacy of regulatory 
mechanisms for protecting white-tailed prairie dogs is discussed under 
factor D. Poisoning, invasive species, drought, and climate change 
impacts are discussed under factor E.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of the Species' Habitat or Range.

    With respect to destruction, modification, or curtailment of the 
species' habitat or range, the petition asserts that oil, gas, and 
mineral exploration and extraction processes destroy and fragment 
white-tailed prairie dog habitat. The petitioners claim that human 
activities associated with oil and gas development, including seismic 
activities and the construction and operation of well pads, roads, and 
other equipment and facilities, fragment habitat and negatively impact 
white-tailed prairie dogs. In addition, they assert that associated 
structures create raptor perches and increase predation risk on prairie 
dogs in the area. The petitioners also assert that associated roads and 
increased access facilitate recreational shooting. They also contend 
that the aforementioned activities damage native vegetation and 
introduce invasive species that quickly take hold. The petitioners 
claim that this vegetation damage and invasive species introduction 
results in further permanent loss of habitat.
    The Conservation Assessment similarly concludes that oil and gas 
development, especially with decreased well spacing, will result in 
``large amounts of habitat lost due to road development and well pad 
construction'' and states that the habitat will remain fragmented and 
lost. The Conservation Assessment also states that vibroseis (seismic 
exploration) may affect prairie dogs by collapsing tunnel systems, 
causing auditory impairment, and disrupting social structures (Clark 
1986, as cited by Seglund et al. 2004). The Conservation Assessment 
also notes that coalbed methane development, including well 
development, pipelines, roads, and compressor sites, can increase human 
disturbance and habitat fragmentation and loss. Establishment of well 
pads and roads facilitate increased vehicular traffic, which may 
increase the risk of direct and indirect mortality (Seglund et al. 
    However, neither the petition nor the Conservation Assessment 
provide substantial scientific information beyond supposition and 
conjecture that oil and gas development results in losses of large 
amounts of habitat. The assertion of habitat fragmentation is not 
supported by substantial scientific evidence. In fact, the Conservation 
Assessment notes in some areas prairie dogs have continued to inhabit 
space where development is occurring. Neither the petition nor the 
Assessment provide substantial scientific information supporting the 
assertion that predation is increased by oil and gas development. No 
scientific information is provided that supports the assertion that 
direct and indirect mortality is affected by road construction or 
vehicular traffic. Both the petition and the Conservation Assessment 
note that large amounts of habitat will be lost to oil and gas 
development, and refer to the fact that the primary sites for oil and 
gas development occur within white-tailed prairie dog range. However, 
neither document provides substantial scientific information supporting 
the claim that large amounts of habitat will be lost to these 
activities. The assertion regarding the effects of vibroseis is 
unsupported by substantial scientific information. While the assertion 
that increased human disturbance is valid by inspection, there is no 
scientific information presented that substantiates its effect on 
prairie dogs.
    The Conservation Assessment estimates 55 percent of the total 
occupied white-tailed prairie dog habitat is under BLM jurisdiction. 
Analyses of available geographic information systems (GIS) data shows 
that 25 percent of white-tailed prairie dog gross range in Utah is 
leased or encompassed by active combined oil and gas fields.
    The petition reports that, in 2001, the BLM approved leases for 669 
oil and gas areas encompassing 293,771 ha (725,925 ac) in Colorado; 295 
oil and gas leases on 218,846 ha (540,780 ac) in Montana; 198 oil and 
gas leases on 132,386 ha (327,133 ac) in Utah; and 1,047 oil and gas 
leases on 457,728 ha (1,131,071 ac) in Wyoming. However, these are 
state-wide totals and it is not known what percentage of these areas 
overlap white-tailed prairie dog predicted range or occupied habitat. 
It should also be noted that not all leased lands are developed 
depending upon the results of exploration activities. Neither the 
petition nor Conservation Assessment present substantial scientific 
information on the effect in the species in terms of actual habitat 
    In Colorado, oil and gas leasing and development is ongoing and 
proposed in occupied white-tailed prairie dog habitat. For example, the 
petitioners allege that 80 percent of the Little Snake Black-footed 
Ferret Management Area is considered of highest potential for oil and 
gas development. According to the petition, there are 7 oil and gas 
fields encompassing 355 wells within the Management Area, and the BLM 
Little Snake Field Office is evaluating the potential for additional 
coalbed methane development. Colorado's largest oil field, the Rangely 
Oil Field in Rio Blanco County, occupies 12,000 ha (30,000 ac) and 
overlaps with 3,000 ha (7,000 ac) of suitable white-tailed prairie dog 
habitat (Wolf Creek Work Group 2001). The overlap of the Rangely Oil 
Field and white-tailed prairie dog habitat represents 5 percent of 
estimated white-tailed prairie dog habitat in Colorado (Knowles 2002). 
Impacts on this development on population levels have not been well 
studied and neither the petition nor the Assessment provide substantial 
scientific information that the Rangley Oil Field may result in a 5% 
reduction in Colorado white-tailed prairie dog habitat nor that the 
Little Snake Black-footed Ferret management area maybe threatened with 
development that will harm white-tailed prairie dog habitat (for an in-
depth discussion of this see the discussion on regulatory protections).

[[Page 64895]]

    Oil, gas, and coalbed methane drilling continues in Utah, primarily 
in the Price Field Office area of the BLM, and in the Uintah Basin in 
northeastern Utah. The petitioners claim that between 1911 and 2000, a 
total of 8,737 wells were drilled in the Uintah Basin, Utah, where the 
large Coyote Basin, Kennedy Wash, Snake John, and Shiner Basin white-
tailed prairie dog complexes occur. The petitioners estimate that 
energy exploration in the Uintah Basin represents 57 percent of all 
wells drilled in the State of Utah. Over three thimes the 10-year 
average of wells was approved in 2001 in the Uintah Basin's BLM Vernal 
Field Office area. It is not known how many of these wells remain 
active. Analyses of GIS data demonstrate that oil and gas leases and 
active combined fields overlap with approximately 55 percent of 
occupied white-tailed prairie dog habitat. However, neither the 
petition nor the Conservation Assessment provide substantial 
information that this development may have or may contribute to a 
curtailment of the species range.
    The Conservation Assessment estimates that approximately 75 percent 
of predicted white-tailed prairie dog range occurs in Wyoming, of which 
77 percent of the white-tailed prairie dog range in Wyoming has the 
potential to undergo or is undergoing oil and gas development to some 
degree (Seglund et al. 2004). The petition describes oil and gas 
development in Wyoming by BLM Field Office areas. According to the 
petition, most oil and gas development in the Casper Field Office area 
is occurring within white-tailed prairie dog range. Over the last 10 
years, an average of 50 new wells has been drilled annually (W. 
Fitzgerald, BLM Casper Field Office, pers. comm., as cited in Center 
for Native Ecosystems 2002). The loss of habitat in the Cody Field 
Office area is attributed primarily to oil and gas development. Recent 
estimates of oil and gas well activity were not cited by the petition. 
The petitioners describe the Moxa Arch natural gas field, with 
approximately 50 to 100 new wells being drilled annually, as occupying 
approximately half of the white-tailed prairie dog habitat within the 
Kemmerer Field Office area (V. Phinney, BLM Kemmerer Field Office, 
pers. comm., as cited in Center for Native Ecosystems 2002). The 
petitioners report that as of December 2001, oil and gas projects in 
the Pinedale Field Office area comprised approximately 266,661 total ha 
(658,933 ac), with 3,111 approved well locations and 1,433 wells 
drilled. According to the petition, most of these fields (including the 
Pinedale Anticline Natural Gas project and Jonah II field) were located 
in and around prairie dog colonies. The petitioners further state that 
in the Rawlins Field Office area, up to 3,000 wells may be approved for 
the Continental Divide project (an oil and gas field development) which 
overlaps with white-tailed prairie dog habitat. This area already has 
2,130 existing wells. Potential impacts of this future development are 
difficult to predict. While the petitioners provide substantial 
information regarding the number and location of oil and gas 
development, they do not provide substantial scientific information 
indicating that these developments affect prairie dog use of habitat. 
As a result, potential impacts of this future development are difficult 
to predict, thus we cannot conclude that the petitioners have provided 
substantial scientific information that it may result in a threatened 
or current loss of habitat.
    The petition describes possible direct impacts from oil and gas 
development, including: clearing and crushing of vegetation, reduction 
of available habitat due to pad construction, road development and well 
operation, displacement and killing of animals, alteration of surface 
water drainage and increased compaction of soils (USFWS 1990, as cited 
by Seglund et al. 2004). However they do not provide substantial 
scientific information to support their assertions and thus we are not 
able to conclude that the adverse effects to prairie dogs may occur. 
For example, the Assessment cites one study that attempted to 
demonstrate the effects of oil and gas disturbance on white-tailed 
prairie dogs and information from that study is preliminary (Baroch et 
al. 2004, as cited by Seglund et al. 2004). The study observed 
population declines, but was unable to determine if the declines were 
attributed to oil and gas development activities or to other factors 
such as plague. In some instances, white-tailed prairie dogs continue 
to inhabit areas developed for oil and gas. Within Coal Oil Basin's 
Rangely Oil Field, where the majority of the area was drilled before 
1984 at a spacing of one well every 8 ha (20 ac), white-tailed prairie 
dogs are consistently present (E. Hollowed, BLM, pers. comm. 2004). 
However, no formal monitoring information exists for the Rangely Oil 
Field; conclusions are based on informal observations. With the limited 
amount of information provided, it is not possible to determine that 
these oil and gas development activities adversely affect white-tailed 
prairie dogs.
    Animal population densities should not always be presumed to be a 
direct measure of habitat quality (Van Horne 1983). Several studies 
show that white-tailed prairie dogs with higher density populations in 
areas of poor quality habitat exhibited lower body mass, delayed sexual 
maturity, and delayed dispersal when compared to relatively 
undisturbed, high quality habitats (Van Horne 1983, Rayor 1985, Dawson 
1991, Trevino-Villareal and Grant 1998). Furthermore, habitat loss or 
degradation can result in reduction of the area and extent of colonies 
even when densities in the remaining areas remain higher (Johnson and 
Collinge 2004). Over the long-term, these factors could lead to 
population declines (Johnson and Collinge 2004). The petitioners do not 
provide substantial scientific information on how oil and gas 
development activities might reduce habitat in ways that affect white-
tailed prairie dog reproduction and survival.
    Beyond direct impacts from oil and gas activity, the Conservation 
Assessment suggests that indirect effects might occur if habitat 
adjacent to white-tailed prairie dog complexes is not maintained to 
allow complexes to shift on a landscape scale in response to plague and 
other factors. However, neither the petition nor the Conservation 
Assessment provides substantial information as to the need or acreage 
required to ensure conservation of local prairie dog populations.
    Neither the petition nor the Conservation Assessment provide 
substantial scientific information supporting the assertion that 
predation is increased by oil and gas development. The assertion 
regarding the effect of vibroseis is unsupported by substantial 
scientific information. There is little scientific information to 
substantiate the effect of increased human disturbance on prairie dogs. 
Magle (2003) studied effects of human presence on a black-tailed 
prairie dog colony in Colorado. He observed prairie dog avoidance 
behaviors; i.e., prairie dogs retreating to their burrows, in response 
to humans walking through a colony.
    The petition and Conservation Assessment do not provide specific 
total acreages or distribution of white-tailed prairie dogs within 
leased areas, nor do they provide complete details of actual oil and 
gas infrastructure distribution relative to prairie dog colonies. Both 
documents identify current or projected threats to the species within 
the foreseeable future including mortality and habitat loss, 
fragmentation, and degradation, and show that current and projected oil 
and gas development extends across the range of the white-

[[Page 64896]]

tailed prairie dog. However, while both documents identify current or 
projected threats to the species due to oil and gas development impacts 
to habitat, the identified threats are speculative and neither document 
provides substantial scientific or commercial information supporting 
the speculation.
    The petition cites agricultural land conversion and urbanization as 
causing some losses of white-tailed prairie dog habitat on a local 
scale. In Montana, historic land conversions for agricultural purposes 
have contributed to white-tailed prairie dog range contraction (Parks 
et al. 1999, as cited in Knowles 2002). The Conservation Assessment 
states that, in some cases, agricultural lands can be beneficial to 
white-tailed prairie dogs by providing foraging habitat. However, if 
the agricultural area requires repeated tilling during the growing 
season, prairie dogs will not be able to inhabit the area. In addition, 
the Conservation Assessment points out that prairie dog colonies in or 
adjacent to agricultural areas frequently are subject to control 
efforts. According to the Conservation Assessment, agriculture 
comprises only 3.7 percent of the species' gross historic range. 
Seglund (et al. 2004) thus concluded, loss of habitat from agricultural 
conversion is significant only on a local scale and is not a range-wide 
    The petition and Conservation Assessment specifically refer to 
urbanization in the areas of Grand Junction, Delta, and Montrose, 
Colorado, and in the Uintah Basin, Utah. As human populations have 
increased in some of these areas, lands have undergone another type of 
conversion, agriculture to urban use. Conversion from agricultural 
lands to urban lands eliminates prairie dog habitat permanently. 
According to the Conservation Assessment, only 0.2 percent of the 
white-tailed prairie dog gross historic range is impacted by 
urbanization. Seglund (et al. 2004) thus concluded, loss of habitat 
from urbanization is significant only on a local scale and is not a 
range-wide concern.
    The petition identifies livestock overgrazing and fire suppression 
as factors that have degraded white-tailed prairie dog habitat by 
altering plant species composition. Overgrazing is continued heavy 
grazing which goes beyond the recovery capacity of the forage plants 
(Vallentine 1990). Fire suppression in shrub steppe habitats has 
resulted in areas dominated with late-successional, homogenous stands 
of shrubs. With fire, shrublands are mosaic of herbaceous and shrub 
vegetation at varied successional stages (Klebenow 1972, as cited in 
Fischer et al. 1996). Combined overgrazing and fire suppression can 
result in the proliferation of shrub species and the spread of noxious 
weeds. Livestock also may trample and destroy biological (cryptogamic) 
soil crusts, increasing erosion and decreasing nutrient cycling. The 
petition concludes that resultant habitat alterations reduce forage 
availability, reduce forage diversity, and degrade the overall quality 
of available habitat.
    It is unclear how significant a factor livestock grazing, fire 
suppression and desertification play in white-tailed prairie dog 
viability. Although the Conservation Assessment initially states that 
public rangelands have seen recent measurable improvements in range 
conditions, the Conservation Assessment and the petition both reference 
BLM's finding that 68 percent of the public rangelands are rated as 
degraded or unsatisfactory (U.S. General Accounting Office 1988, 1991). 
Because 55 percent of white-tailed prairie dog occurs on BLM land, this 
is an important consideration. However, neither the petition nor 
Conservation Assessment provide substantial scientific information 
demonstrating that livestock grazing or fire suppression are threatened 
or present sources of habitat loss.
    Based on the preceding discussion, we do not believe that 
substantial information is available indicating that present or 
threatened destruction, modification, or curtailment of habitat or 
range may, either singularly or in combination with other factors, rise 
to the level of a threat to the continued existence of the species over 
a significant portion of the species range. While factors affecting 
habitat are in some cases (e.g., oil and gas development, grazing, fire 
suppression) occurring across the range of white-tailed prairie dog no 
information as to the rangewide extent of these activities in terms of 
scale was provided. In addition, neither the petition nor the 
Conservation Assessment provided substantial scientific information on 
the actual overlap and effects of habitat losses and degradation 
associated with these factors relative to the distribution of white-
tailed prairie dog colonies and complexes.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Shooting closures for white-tailed prairie dogs have been 
implemented year-round in Coyote Basin, Utah and seasonally (April 1-
June 15) on all other public lands in Utah. Year round shooting 
closures also apply to white-tailed prairie dogs on federal lands 
throughout their range in Montana. Wyoming implements a shooting 
closure on a 1,917 ha (4,737 ac) conservation easement at Shirley 
Basin. No shooting closures exist for white-tailed prairie dogs in 
Colorado (Seglund et al. 2004).
    The petition cites Knowles (1988) to assert that unregulated 
shooting of white-tailed prairie dogs in Colorado and Wyoming has had 
negative impacts. In Colorado counties with white-tailed prairie dogs, 
harvest statistics from 1999-2003 estimate that 28,005 individual 
prairie dogs were shot annually (CDOW 2002, cited by Center for Native 
Ecosystems 2002). Based on research, lactating females spend more time 
above ground during the months of April through July (Tileston and 
Lechleitner 1966, Bakko and Brown 1967). During this time, adult male 
activity decreases (Bakko and Brown 1967). The petition asserts if 
shooting occurs during these times, the female and juvenile prairie 
dogs are more vulnerable than males (Center for Native Ecosystems 
2002). According to the Conservation Assessment, peak shooting pressure 
on white-tailed prairie dog colonies occurs in May and June when the 
weather is cooler and juveniles are emerging. The CDOW estimates that 
juvenile prairie dogs likely make up a disproportionately high 
percentage of prairie dogs shot (Keffer et al. 2000). The petitioners 
note that due to the disproportionate vulnerability of adult female and 
juvenile prairie dogs, it is reasonable to see how the demographic 
structure of shot colonies may differ from that of unshot colonies. The 
petitioners further reason that shooting may have further implications 
on behavior, emigration, and population density.
    Neither the petition nor the Conservation Assessment provides 
substantial scientific information on the long-term impacts of 
recreational shooting on white-tailed prairie dogs. Shooting has the 
potential to locally reduce population densities and could slow or 
preclude recovery rates of colonies reduced by plague or other 
disturbances by being an additive factor to mortality. Available 
studies of recreational shooting at black-tailed prairie dog colonies 
have shown short-term colony population declines and behavioral changes 
(Knowles 1988, Vosburgh and Irby 1998). However, neither the petition 
nor the Conservation Assessment provides substantial scientific 
information on the long-term effects of this threat.

[[Page 64897]]

C. Disease or Predation

    White-tailed prairie dogs are prey species for many mammalian and 
avian predators. These predators include black-footed ferrets, hawks, 
eagles, badgers (Taxidea taxus) and coyotes (Canis latrans). Predation 
does not appear to exert a controlling influence on prairie dog density 
(King 1955 as cited in Seglund et al. 2004, Tileston and Lechleitner 
1966, Clark 1977).
    The petition asserts that sylvatic plague is the main threat to 
white-tailed prairie dog persistence (Biggins and Kosoy 2001, Knowles 
2002). Plague is caused by a bacterium (Yersinia pestis) not native to 
North America; fleas are commonly the vectors (Biggins and Kosoy 2001). 
Plague results in local extirpations, reduced colony sizes, increased 
variation in local population sizes, and increased distances between 
colonies (Cully and Williams 2001). All prairie dog species have shown 
high susceptibility to plague (Williams 1986). White-tailed prairie dog 
population declines of 85 to 96 percent within an epizootic event have 
been documented (Anderson and Williams 1997, Clark 1977).
    Plague was probably introduced to the United States from Asia circa 
1899 (Barnes 1982). The first record of plague in native mammals in 
North America was near Berkeley, California in 1908 among California 
ground squirrels (Spermophilus beecheye) (McCoy 1908, Wherry 1908, as 
cited by Cully 1993). Since then, plague moved eastward. According to 
the Centers for Disease Control (2002, as cited by Antolin et al. 
2002), sylvatic plague is now distributed from the west coast to its 
eastern extant stretching along the 102nd meridian from North Dakota 
south to the 97th meridian in Texas. Within those east-west confines, 
plague is present from the Canadian to the Mexican border. The white-
tailed prairie dog range falls well within these boundaries.
    The first white-tailed prairie dog plague case was confirmed in 
1936 (Eskey and Haas 1940). We do not have data to indicate that all 
white-tailed prairie dogs were exposed to plague at this time or the 
same time. Systematic white-tailed prairie dog surveys did not begin 
until the 1980's (when there was an effort to find black-footed ferret 
recovery or reintroduction sites) (Biggins and Kosoy 2001). At that 
time, the first recorded plague outbreaks were observed (Fagerstone and 
Biggins 1986a, as cited by Biggins 2003b). For example, in Meeteetse, 
Wyoming, plague was first recorded in 1985 when the population crashed. 
This large decline in a short amount of time was an epizootic event. 
Plague was again recorded in this complex between 1989 and 1990, and 
again in 1993 (Anderson and Williams 1993, Cully 1993)
    Plague has now been confirmed across nearly the entire range of the 
white tailed prairie dog (Centers for Disease Control 2002, as cited by 
Antolin et al. 2002), and has had a range-wide impact (Knowles 2002). 
Biggins and Kosoy (2001) note that no examples can be found of plague-
free white-tailed prairie dog populations. Thus, unlike black-tailed 
prairie dogs which maintain plague-free colonies in the eastern portion 
of their range, white-tailed prairie dogs do not have large insulated 
populations protected from the plague organism.
    The petition concludes that individual white-tailed prairie dogs 
may be more susceptible than black-tailed prairie dogs. The petitioners 
cite preliminary research conducted by Dr. Tonie Rocke, a U.S. 
Geological Survey researcher, indicating that white-tailed prairie dogs 
may contract sylvatic plague with exposure to only a few plague bacilli 
versus the many plague bacilli that are required to infect black-tailed 
prairie dogs with plague. Although quite susceptible, plague antibody 
titers have been found in white-tailed prairie dogs, indicating 
exposure and survival of some individuals when exposed to plague (Cully 
and Williams 2001, Biggins 2003a). Cully and Williams (2001) and 
Biggins (2003a) research on plague and prairie dogs in the laboratory 
found one white-tailed prairie dog with an apparent immunity to plague, 
and Biggins (2003a) found 3 out of 154 white-tailed prairie dogs with 
plague antibody titers. However, Biggins (USGS pers. comm. 2004) also 
states that plague antibody titers have been so rare in wild white-
tailed prairie dogs colonies that research efforts were not previously 
directed to the possibility of immunity. Populations of white-tailed 
prairie dogs thus far have remained highly susceptible to plague even 
after repeated exposure (Biggins and Kosoy 2001). There is no 
information on the ability of adults to pass a developed immunity onto 
their offspring.
    Pizzimenti (1975) found that of the five species of prairie dogs in 
the North America, white-tailed prairie dogs have the largest number of 
flea species. This suggests white-tailed prairie dogs may be more 
likely to contract plague from other mammalian species because they are 
more likely to host the same flea species as other mammalian species 
(Pizzimenti 1975). This susceptibility can result in epizootic events 
in which large numbers of animals die within a few days (Cully 1993, 
Lechleitner et al. 1962). Infected fleas have been found to exist in 
burrows for up to 13 months following a plague event (Fitzgerald 1993). 
The continued presence of the disease also can affect low-density 
white-tailed prairie dog colony populations enzootically. Enzootic 
plague causes some mortality within the colony, but not all individuals 
become affected simultaneously because of low density and reduced 
contact. Therefore, low-density populations remain at low densities. 
Plague not only results in the loss of large numbers of individual 
animals, it also may alter population dynamics, dispersal, and may 
result in secondary impacts to habitat.
    Responses of white-tailed prairie dog populations to plague are 
reportedly variable over the long term, because of intrinsic and 
extrinsic factors. Superficially, some social and behavioral traits of 
white-tailed prairie dogs appear to favor their long-term persistence 
in a plague environment (Biggins and Kosoy 2001), in comparison to 
other prairie dog species. The rate of spread of a plague epizootic is 
dependent on the density of the host population density (Barnes 1982). 
White-tailed prairie dog colonies are less dense and more widely 
dispersed than black-tailed or Gunnison's prairie dog colonies, which 
may slow transmission rates (Cully 1993, Cully and Williams 2001, Eskey 
and Haas 1940). Looser social structures and hibernation behavior 
displayed by white-tailed prairie dogs also may reduce transmission 
among individual animals (Cully 1993, Cully and Williams 2001). 
However, Barnes (1993) suggested hibernation may simply delay the onset 
of symptoms throughout all the colonies. Conversely, the Conservation 
Assessment also concludes that other environmental and human-caused 
factors could decrease the ability of populations to recover long-term.
    Consequently, while some behavioral traits (e.g., migratory 
abilities and hibernation) of white-tailed prairie dogs are often 
reported to buffer adverse effects of plague, the information is 
neither clear nor conclusive. For example, migration within complexes 
may promote recolonization of colonies previously impacted by plague; 
conversely, intercolony movement also may contribute to disease 
transmission, and isolated colonies are less likely to support 
sufficient immigration for long-term persistence of plague-affected 
colonies (Seglund et al. 2004).
    In addition, the Conservation Assessment and Knowles (2002) raise 
concerns that white-tailed prairie dog

[[Page 64898]]

plague cycles (i.e., epizootic, recovery, epizootic) result in 
successive population peaks that are progressively lower than the 
previous peak and that with each new epizootic, the loss of colonies 
from plague exceeds the rate of new colony establishment. This cycle of 
peaks and crashes is further supported by observations of frequent 
recurrence of plague in white-tailed prairie dog colonies (Cully 1993, 
Barnes 1993). The Conservation Assessment reports that colony recovery 
rates have been reported to occur within as little as 1-2 years 
(Anderson and Williams 1997), or within as much as 10 years (Cully and 
Williams 2001). Colonies affected by plague have shown varying recovery 
responses. The Conservation Assessment reports post-plague recovery 
occurring in Wyoming's Shirley Basin, Colorado's Wolf Creek, and Utah's 
Kennedy Wash. Conversely, some large colonies have continued to decline 
or remained at low numbers since the occurrence of plague, such as 
Wyoming's Meeteetse, Colorado's Little Snake, and Utah's Cisco. 
However, for most sites, historical data are not available to compare 
apparent colony recovery levels with their historical or pre-plague 
densities. In addition, and importantly, because white-tailed prairie 
dogs exist in smaller numbers than black-tailed prairie dogs, plague 
epizootics could have a more significant influence on their viability.
    Regardless of social and behavioral factors, some of the largest 
white-tailed prairie dog complexes at Meeteetse, Cisco, and Little 
Snake have declined significantly as a result of plague, and have not 
fully recovered to their pre-plague abundance. In addition, the 
petition identifies the presence of plague in low-density and medium-
density white-tailed prairie dog colonies. Other animals also can 
transmit plague between prairie dog colonies (Cully and Williams 2001). 
This suggests that many, if not all, colonies of white-tailed prairie 
dogs are vulnerable to plague regardless of size, degree of isolation, 
and density. The Conservation Assessment concludes that ``sylvatic 
plague has the potential to rise to the level of a threat to the 
continued existence of the species, but the threat is non-imminent'' 
and, ``concern over the long-term viability of white-tailed prairie dog 
populations is warranted.'' They also state that ``the role that plague 
has played and will play in the overall decline of white-tailed prairie 
dogs is a critical question for future management and research.''
    Because of the lack of long-term data or a detailed understanding 
of plague and white-tailed prairie dog dynamics, both the petition and 
Conservation Assessment conclude that long-term monitoring over large 
areas is essential to determine population effects of the disease. The 
petition and Conservation Assessment provide the following examples of 
large colonies that declined because of confirmed or suspected plague 
with some level of population rebound in a couple of cases. Plague was 
suspected when colonies crashed within a short timeframe.
    Little Snake Complex, Colorado--Some decline was suspected in 1983 
(USFWS et al. 1995). Sylvatic plague was confirmed in 1994 in flea 
samples and in 1995 in coyote blood samples. Between 1994 and 1999, 
colony size declined 90 percent. The Conservation Assessment reports 
likely continued declines in 2002, but a possible small increase in 
2003. However, drought-related declines in sagebrush and forbs also 
were noted in 2003; so, it is unclear if the noted small increase will 
    Wolf Creek Complex, Colorado--From 1985 to 1987, populations west 
of Massadona were reduced to about 10 percent of their former 
abundance. Although partial recovery occurred between 1990 and 1993, 
declines have occurred since then and the population has not recovered 
to its pre-1985 abundance. In 2001, population numbers were estimated 
to be 40 percent lower than in 1993-1994 (Wolf Creek Work Group 2001). 
Although no reason for the decline is given, the petition cites a 
personal communication from E. Hollowed (BLM 2004) reporting sylvatic 
plague in the area since at least 1997.
    Montrose County, Colorado--Declines have been noted in these 
colonies since 1978, but the role of plague is unclear. The petition 
reports declines may be a cumulative result of plague, shooting, and 
    Colorado National Monument, Colorado--The petition sites a personal 
communication reporting that prairie dog populations in the area 
crashed after a 1976 plague epizootic. It is not known if any prairie 
dogs still inhabit the Monument.
    Montana--The petition identifies seven white-tailed prairie dog 
colonies in Montana that were extirpated and cites personal 
communication with D. Flath attributing those extirpations to plague 
    Kennedy Wash Subcomplex, Utah--The petitioners report the white-
tailed prairie dog population in this subcomplex undergoing major 
declines in 1999 due to plague. Personal communication from B. Bibles 
(Uinta Basin USU Extension Branch) was cited by the petitioners as 
stating that plague has continued in the area enzootically (constantly 
present in an animal community but only occurs in a small number of 
cases). The petition reports prairie dog densities declining from 5.4 
dogs per ha (2.1 dogs per ha) in 1999 to 3.1 dogs per ha (1.2 dogs per 
ha) in 2001. The Conservation Assessment reports a subsequent 
population increase in 2002, followed by a significant decline in 2003.
    Shiner Subcomplex, Utah--Surveys in Shiner Basin from 1997 to 2000 
documented a decline from 47,551 prairie dogs in 1998 to 5,383 prairie 
dogs in 1999 (Seglund et al. 2004). Such a decline in a short period of 
time is characteristic of plague epizootic impacts on prairie dog 
populations. The petition notes some partial recovery in 2000. The 
Conservation Assessment describes surveys in 2002 and 2003 that show 
low densities and little, if any, population recovery.
    Snake John Subcomplex, Utah--The petition documents possible 
population increases between 1989 and 2001, while the Conservation 
Assessment reports a significant population decline in 2003. The cause 
of the 2003 decline is not reported; however, it is reasonable to 
suspect plague given the colony's proximity to Kennedy Wash and the 
substantial decline in a short amount of time.
    Cisco Complex, Utah--Between 1985 and 1992, transect counts show 
that prairie dog populations increased dramatically. Population 
declines, likely due to plague, were observed from 1998-2002. Complex 
remapping in 2002 yielded 1,085 ha (2,682 ac) of occupied habitat, 
apparently low relative to historic acreages (Seglund et al. 2004).
    Dinosaur National Monument, Utah--The petition cites a personal 
communication from S. Petersburg estimating that a substantial plague-
related decline occurred at the Monument colony between the late 1980s 
and early 1990s, but that this population may now be increasing. 
Specific data are not provided.
    Meeteetse Complex, Wyoming--Plague epizootics swept through this 
complex four times between 1964 and 1985 (Clark et al. 1985, Ubico et 
al. 1988, Clark 1989). Between 1988 and 1997, plague resulted in the 
loss of 18,400 white-tailed prairie dogs, an estimated 72 percent 
decline in the complex (Biggins 2003b). This complex has experienced no 
significant recovery (Knowles 2002).
    Shirley Basin Complex, Wyoming--The petition reports a 50 percent 
decline in occupied prairie dog habitat from 1990 to 2000, and an 
estimated 78

[[Page 64899]]

percent population decline (B. Oakleaf, pers. comm., as cited by Center 
for Native Ecosystems 2002). The WGFD conducted surveys of selected 
prairie dog colonies between 1992 and 2001 which indicated that white-
tailed prairie dog abundance appeared to have decreased (Seglund et al. 
2004). However, given recent increases, Grenier et al. (2003 as cited 
by Seglund et al. 2004) reported a 50 percent increase in occupied 
habitat from 1990 to 2004 over a different portion of the Shirley Basin 
complex (Seglund et al. 2004).
    Kinney Rim, Wyoming--The Kinney Rim complex was first sampled in 
1989 with 7,215 ha (17,828 ac) of occupied habitat reported. It was 
suspected that sylvatic plague was impacting the complex during the 
1989 survey, although no attempts were made to confirm presence of 
plague. The area was partially inventoried, again, in 1993 suggesting 
an increase (Conway 1989 and Albee 1993, as cited in Seglund et al. 
2004). The petition cites personal communications from B. Luce 
documenting substantial declines at this complex by 1995. No more 
recent conclusive data are reported.
    Polecat Bench, Wyoming--Population numbers and accurate occupied 
acreage data are unavailable for this complex. A personal communication 
from D. Saville (Cody BLM Office) in the petition concluded that the 
complex experienced major plague-caused declines between 1979 and 1981. 
According to the petition, recovery at this site has been slow, similar 
to the post plague population response reported at the Meeteetse 
    The petitioners assert that tularemia is another pathogen that can 
cause disease-related declines in white-tailed prairie dog populations 
(Davis 1935). However, there is little data on its prevalence. Long-
term impacts of this disease on white-tailed prairie dog populations 
are unknown (Barnes 1993).
    West Nile virus is a recent disease with unknown ramifications for 
white-tailed prairie dog populations. A black-tailed prairie dog was 
reported to have died of this disease in Boulder, Colorado, in 2003 
(Seglund et al. 2004). We are unaware of any confirmed incidences of 
West Nile virus in white-tailed prairie dogs.
    Because of the lack of long-term data or an understanding of plague 
and white-tailed prairie dog dynamics, both the petition and 
Conservation Assessment conclude that long-term monitoring over large 
areas is essential to determine population effects of the disease. On 
this basis, we believe the petition, the Conservation Assessment, and 
other information readily available to us do not provide substantial 
scientific information to indicate that disease may be a threat to the 
viability of the white-tailed prairie dog. We make this finding while 
recognizing that the source materials are primarily from white-tailed 
prairie dog complexes inventoried for black-footed ferret recovery. 
Because the black-footed ferret recovery work identified only those 
complexes meeting black-footed ferret prey needs (i.e., generally large 
in area, and densely occupied by prairie dogs), there is a legitimate 
concern that the data may not accurately reflect prairie dog trends at 
all colonies throughout the prairie dog's range. As noted above 
however, the information regarding the relationship of prairie dog 
colony size and prairie dog behavior to plague susceptibility is not 

D. The Inadequacy of Existing Regulatory Mechanisms

    The petition claims that white-tailed prairie dogs have been 
negatively affected by the lack of Federal and State regulations, to 
control poisoning, shooting, or habitat destruction. The petition also 
asserts that current State and Federal regulations do not adequately 
address the potential impacts of oil, gas, and mineral extraction on 
white-tailed prairie dog habitat (see factor A), nor do they provide 
adequate mitigation.
    All BLM Field Offices whose jurisdictions include black-footed 
ferret reintroduction areas will have stipulations related to black-
footed ferret habitat protection. While these stipulations are not 
intended to address white-tailed prairie dog conservation per se, they 
serve to protect some white-tailed prairie dog habitat because the 
white-tailed prairie dog is the primary food source available to black-
footed ferrets. All black-footed ferrets in the wild have a designation 
of ``experimental, non-essential'' pursuant to section 10(j) of the 
Act. Experimental, non-essential populations are treated as proposed 
species for section 7 consultation purposes, which means that 
consultation with the Service is only required if the project is likely 
to jeopardize the continued existence of the species although generally 
federal agencies routinely consult with the we on species proposed for 
listing and 10(j) populations.
    In addition, black-footed ferret reintroductions have occurred in 
only three white-tailed prairie dog complexes including Coyote Basin 
(Utah), Wolf Creek (Colorado), and Shirley Basin (Wyoming). All other 
white-tailed prairie dog colonies occur outside of ferret 
reintroduction areas and thus would see only limited benefit from 
ferret conservation measures such as ferret survey requirements in 
potential ferret habitat as defined by prairie dog colony size.
    In Colorado, the white-tailed prairie dog range occurs within the 
jurisdiction of six BLM field offices, with four of these field offices 
having no stipulations specific to white-tailed prairie dog for oil and 
gas development in white-tailed prairie dog habitat (R. Sell, BLM, 
pers. comm., as cited by Seglund et al. 2004). However, a number of 
general stipulations on such development will protect white-tailed 
prairie dog habitat.
    In Utah, the white-tailed prairie dog range occurs within the 
jurisdiction of the BLM's Vernal Field Office, which includes Coyote 
Basin Black-footed Ferret Reintroduction Area, which has stipulations 
related to black-footed ferret habitat protection but does not 
specifically address white-tailed prairie dog conservation (B. Zwetzig, 
BLM, pers. comm., as cited by Seglund et al. 2004). The white-tailed 
prairie dog range also occurs within the jurisdiction of the Price and 
Moab Field Offices, which do not have directives with regard to white-
tailed prairie dog management. However, both of these field offices are 
currently revising their Land Use Plans and the new plans will consider 
the white-tailed prairie dog in special status species alternatives (S. 
Madsen, P. Riddle, BLM, pers. comm., as cited by Seglund et al. 2004), 
which would carry with it protections similar to those for species 
protected under the ESA.
    The Montana policy regarding white-tailed prairie dogs is related 
to potential black-footed ferret reintroductions (J. Parks, BLM, pers. 
comm., as cited by Seglund et al. 2004). ``Prior to surface 
disturbance, prairie dog colonies and complexes of 32 ha (80 ac) or 
greater in size will be examined to determine the absence or presence 
of black-footed ferrets.'' Currently Montana has only a small amount of 
active white-tailed prairie dog habitat and no overlap with oil and gas 
    The BLM in Wyoming has declared the white-tailed prairie dog a BLM 
sensitive species. This designation carries with it, through 
regulation, habitat and species protections similar to those afforded 
candidate species under the Act. There are eight BLM resource areas in 
Wyoming within the range of the white-tailed prairie dog, and all of 
these resource areas are conducting some form of prairie dog 
management. The Wyoming BLM is currently revising its Resource 
Management Plans (RMP) in the white-

[[Page 64900]]

tailed prairie dog range. These RMP revisions are primarily driven by a 
recent emphasis on oil and gas development activity, and are or will be 
addressing white-tailed prairie dogs. The BLM also has had nominations 
submitted by several environmental groups for the designation of 
prairie dog ``areas of critical environmental concern.'' A BLM 
Statewide, programmatic, biological evaluation is being prepared for 
white-tailed prairie dogs, the results of which will be incorporated 
into RMPs.
    The Conservation Assessment concludes that many State Field Offices 
in Wyoming, Utah, Colorado, and Montana currently do not consider the 
white-tailed prairie dog in oil and gas development unless it is 
associated with black-footed ferret reintroduction efforts. Because of 
this, most current BLM plans throughout the range of the white-tailed 
prairie dog do not address white-tailed prairie dog species-specific 
needs, but addresses white-tailed prairie dog as black-footed ferret 
habitat. In addition, they do not address maintaining habitat for 
expansion and shifts in occurrence outside of currently mapped colonies 
and they address impacts at a colony level rather than a complex or 
landscape level. Finally, RMPs do not address the impact of road 
development and the potential for an increase in shooting/direct take 
of white-tailed prairie dog as a result of oil and gas development. 
Colorado and Wyoming allow yearlong shooting on public lands, except 
for the shooting closure on the 1,917 ha (4,737 ac) conservation 
easement at Shirley Basin, Wyoming.
    The Petroleum Association of Wyoming asserts that a number of lease 
stipulations and conditions designed to protect big game species, 
mountain plover (Charadrius montanus), raptors, black-footed ferrets, 
sage-grouse (Centrocercus urophasianus), and other threatened, 
endangered and candidate species also benefit white-tailed prairie dog 
(Bower, in litt. 2004). Specifically, it noted that oil and gas surface 
activity is banned on designated mountain plover habitat from mid-April 
through early July unless surveys show that no plovers are present 
(Bower, in litt. 2004). Oil and gas surface activity is banned within a 
0.8 to 1.6 km (0.5 to 1.0 mi) radius of active raptor nests on Federal 
lands during the raptors breeding and young-rearing seasons (February 
through July depending on the species) (Bower, in litt. 2004). Further, 
white-tailed prairie dog complexes in excess of 81 ha (200 ac) are off 
limits to oil and gas development until black-footed ferret surveys 
have been conducted and towns are cleared (Bower, in litt. 2004). Other 
lease stipulations prohibit drilling between March 1 and June 30 to 
protect sage-grouse breeding, nesting, and brood-rearing. Finally, 
surface disturbances are prohibited from November 15 and April 30 to 
protect wintering big game animals. These restrictions may benefit 
white-tailed prairie dog populations in some instances, if they are co-
    The petition asserts that unregulated poisoning alone has reduced 
prairie dog abundance in Wyoming by an estimated 75 percent since 1915 
(Campbell and Clark 1981). Although large-scale poisoning may have 
occurred in the past, toxicant control is not considered a significant 
factor shaping white-tailed prairie dog population dynamics. This 
factor is discussed in more detail below under factor E. Limited 
poisoning is still permitted on private lands adjacent to agricultural 
lands or to control expanding colonies. The Conservation Assessment 
recommends the use of incentive programs to encourage land owners to 
minimize the use of toxicants to control white-tailed prairie dog 
    The petitioners and the Conservation Assessment assert that 
recreational shooting in April, May, and June may have greatest 
population level impacts because pregnant and lactating females and 
young-of-the-year are most vulnerable (see Factor B). Shooting has the 
potential to locally reduce population density and could slow or 
preclude recovery rates of colonies reduced by plague or other 
disturbances by being an additive factor to mortality (Seglund et al. 
2004). Montana has implemented a year-round shooting closure on white-
tailed prairie dogs, and Utah recently implemented an April 1-June 15 
seasonal shooting closure on public lands (Seglund et al. 2004). In 
Coyote Basin, Utah, a year-round shooting closure was established to 
improve black-footed ferret habitat. In Shirley Basin/Medicine Bow 
Management Area in Wyoming, permanent shooting closure was implemented 
on a conservation easement of 1,917 ha (4,737 ac). No shooting closures 
have been adopted on any white-tailed prairie dog habitat in Colorado. 
No shooting is permitted on National Wildlife Refuges. The Conservation 
Assessment notes that if shooting can be managed to regulate 
populations and maintain them at a threshold density, it may be a 
useful management tool for prairie dog conservation.
    Current management status varies by State. Colorado currently has 
no management or conservation plan for white-tailed prairie dogs and 
they are not included on the State Species of Concern or State 
threatened and endangered list.
    In January 2002, the Montana Prairie Dog Working Group released the 
``Conservation Plan for Black-tailed and White-tailed Prairie Dogs in 
Montana.'' The stated goal of the plan is to ``provide for management 
of prairie dog populations and habitats to ensure the long-term 
viability of prairie dogs and associated species.'' Accomplishments to 
date that have benefited white-tailed prairie dogs include the 
reclassification of white-tailed prairie dogs as `non-game wildlife 
species in need of management,' the application of a year-round 
shooting closure on white-tailed prairie dogs occupying Federal lands, 
and a draft Environmental Assessment anticipating translocation of 
prairie dogs from Montana and Wyoming sites to formerly occupied 
colonies. White-tailed prairie dogs are also listed on the Species of 
Concern List compiled by the Montana Natural Heritage Program and 
Montana Fish Wildlife and Parks and used to prioritize research and 
management needs among nongame wildlife species.
    In 2003, Utah Department of Wildlife Resources added the white-
tailed prairie dog to the agency's Sensitive Species List. The list is 
intended to stimulate development and implementation of management 
actions to precluded Federal listing of these species under the ESA. 
However, at this time Utah does not have a management or conservation 
plan for the white-tailed prairie dog.
    The white-tailed prairie dog is classified as a Species of Special 
Concern by the Wyoming Game and Fish Department. Currently, Wyoming 
does not have a management or conservation plan for the white-tailed 
prairie dog but this designation does carry certain protections with 
    In this finding we have addressed the regulatory concerns as they 
relate to a number of factors, however, given that these issues have 
not been identified as significant threats, there is no immediate need 
to consider whether efforts to regulate them are adequate.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    The petition and Conservation Assessment recount a long history of 
rodent and prairie dog poisoning campaigns in the United States. Black-
tailed prairie dogs were the main focus of this eradication. White-
tailed prairie dogs were impacted directly and indirectly. In the 
1970s, several toxicants used to control prairie dog

[[Page 64901]]

populations were banned. Large-scale chemical control programs also 
were phased out. Prairie dog poisoning still occurs on private and 
State lands range wide, but at a much reduced rate and with less 
effective poisons and in specialized circumstances. The Conservation 
Assessment states that poisoning is banned from BLM lands, and 55 
percent of white-tailed prairie dog habitat is on BLM land.
    Invasive weeds, especially cheatgrass (Bromus tectorum), are 
identified by the petitioners as reducing forage quality for white-
tailed prairie dogs. Cheatgrass out-competes other native, plants and 
provides limited seasonal forage for white-tailed prairie dogs (Knapp 
1996). Furthermore, cheatgrass alters fire regimes, fostering an 
environment in which frequent fires further proliferate and maintain 
cheatgrass (Young and Allen 1997, Hull 1965, as cited in Center for 
Native Ecosystems 2002). Cheatgrass establishment depends on the level 
of disturbance in a plant community. Consequently, overgrazing of an 
area, dirt roads, activities that are associated with natural resource 
extraction and off-highway vehicle use can disturb a landscape and 
introduce invasive noxious weeds.
    Drought is another factor mentioned by the petition that may 
negatively impact white-tailed prairie dogs. White-tailed prairie dogs 
exist in arid landscapes. During very dry years, vegetation is less 
abundant for prairie dogs. Prairie dogs obtain most of their water 
requirements through vegetation, and may become water-stressed if 
sufficient succulent vegetation is unavailable (Stockard 1929, Seglund 
et al. 2004). Furthermore, less abundant resources result in lower 
overall body mass (Beck 1994). Beck (1994) conducted research on 
comparing white-tailed prairie dog use of watered and unwatered plots. 
Beck (1994) found that the watered plots were the higher quality 
habitats and consequently promoted higher weaning success for both 
adult and yearling females. Since prairie dogs have evolved with 
occurrences of drought, they have developed means of dealing with the 
shortage of resources such as a lower litter size or earlier initiation 
of hibernation to conserve energy. However, prolonged drought could 
lower overall body condition for white-tailed prairie dogs potentially 
affecting over-winter survival rates. In addition, drought may further 
exacerbate the impacts of other factors, such as non-native sylvatic 
    Both the petition and the Conservation Assessment identify climate 
change, environmental stochastic events, and other human disturbances 
as other possible impacts, but little additional information or 
analysis is provided (Center for Native Ecosystems 2002, Seglund et al. 
    Based on the current information, it does not appear that there is 
substantial scientific information to indicate that natural and manmade 
factors threaten the continued existence of the white-tailed prairie 
dogs throughout a large portion of their range.


    We have reviewed the petition, the Conservation Assessment, and 
other information available in our files. Based on our review of this 
information, we find there is not substantial scientific or commercial 
information to indicate that listing the white-tailed prairie dog may 
be warranted at this time. Both the petition and the Conservation 
Assessment note that plague is the most important factor effecting 
white-tailed prairie dog population dynamics and the long-term 
viability of the species. However, the lack of long-term data or a 
detailed understanding of plague and white-tailed prairie dog dynamics 
indicate that substantial information is not available to determine 
that plague is a threat which may warrant the listing of this species. 
Plague (which occurs across the entire range of the species) and the 
conditions under which white-tailed prairie dogs are affected, both 
epizootically and enzootically, population responses to plague, and 
ensuing long-term population viability, require further evaluation. 
Likewise, the impacts of present and threatened destruction, 
modification, or curtailment of habitat are inadequately known to 
constitute substantial information that listing may be warranted.
    Although we will not be commencing a status review in response to 
this petition, we continue to monitor the species' population status 
and trends, potential threats to the species, and ongoing management 
measures that may be important with regard to the conservation of the 
white-tailed prairie dog throughout its range.

References Cited

    A complete list of our references cited herein is available upon 
request from the Utah field office (see ADDRESSES).


    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: November 2, 2004.
Marshall P. Jones, Jr.,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 04-24878 Filed 11-8-04; 8:45 am]