[Federal Register Volume 69, Number 159 (Wednesday, August 18, 2004)]
[Proposed Rules]
[Pages 51217-51226]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-18872]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; Finding for the 
Resubmitted Petition To List the Black-Tailed Prairie Dog as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Finding on a resubmitted petition.

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SUMMARY: We, the Fish and Wildlife Service (Service), announce our 
resubmitted 12-month petition finding for the black-tailed prairie dog 
(Cynomys ludovicianus). We conclude that the black-tailed prairie dog 
is not likely to become an endangered species within the foreseeable 
future throughout all or a significant portion of its range, pursuant 
to the Endangered Species Act (Act) of 1973, as amended. Therefore, we 
find that proposing a rule to list the species is not warranted, and we 
no longer consider it to be a candidate species for listing. We make 
this determination because recent distribution, abundance, and trend 
data indicate that the threats to the species identified in the 12-
month finding are not as serious as earlier believed.

DATES: This finding was made on August 12, 2004. Although no further 
action will result from this finding, we request that you submit new 
information concerning the status of, or threats to, this species, 
whenever it becomes available.

ADDRESSES: The complete file for this finding is available for 
inspection, by appointment, during normal business hours, at the South 
Dakota Field Office, U.S. Fish and Wildlife Service, 420 S. Garfield 
Avenue, Suite 400, Pierre, South Dakota 57501. Submit new information, 
materials, comments, or questions concerning this species to us at the 
above address. You may obtain a copy of our species assessment for the 
black-tailed prairie dog on the Internet at http://mountain-prairie.fws.gov/species/mammals/btprairiedog/ or by contacting the 
South Dakota Field Office at the above address.

FOR FURTHER INFORMATION CONTACT: Pete Gober, at the South Dakota Field 
Office, (see ADDRESSES section above), by telephone at (605) 224-8693, 
extension 24, by facsimile at (605) 224-9974, or by e-mail [email protected].

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(B) of the Act requires that within 12 months after 
receiving a petition to revise the List of Endangered and Threatened 
Wildlife that contains substantial information indicating that the 
petitioned action may be warranted, the Secretary shall make one of the 
following findings--(a) The petitioned action is not warranted, (b) the 
petitioned action is warranted, or (c) the petitioned action is 
warranted but precluded by pending proposals. Such 12-month findings 
are to be published promptly in the Federal Register. The Act also 
requires that when a warranted but precluded finding is made, a 
petition is treated as resubmitted and the Service is required to 
publish a new petition finding on an annual basis.
    On July 31, 1998, the Service received a petition dated July 30, 
1998, from the National Wildlife Federation (NWF) (1998). The 
petitioner requested that the Service list the black-tailed prairie dog 
(Cynomys ludovicianus) as threatened throughout its range. On August 
26, 1998, the Service received another petition regarding the black-
tailed prairie dog from the Biodiversity Legal Foundation, the Predator 
Project, and Jon C. Sharps (Biodiversity Legal Foundation et al. 1998). 
The Service accepted this second petition as supplemental information 
to the NWF petition. A notice of a 90-day finding for the petition was 
published in the Federal Register on March 25, 1999 (64 FR 14425), 
indicating that it and other readily available scientific and 
commercial information presented substantial information that the 
petitioned action may be warranted. On February 4, 2000, the Service 
announced a 12-month finding that listing the black-tailed prairie dog 
as a threatened species was warranted but precluded by other higher 
priority actions (65 FR 5476). When we find that a petition to list a 
species is warranted but precluded, we refer to the species as being a 
candidate for listing.
    Section 4(b)(3)(B) of the Act directs that, when we make a 
``warranted but precluded'' finding on a petition, we are to treat the 
petition as being one that is resubmitted annually on the date of the 
finding; thus the Act requires us to reassess the petitioned actions 
and to publish a finding on the resubmitted petition on an annual 
basis. Two previous candidate assessments and resubmitted petition 
findings for this species were completed February 7, 2001, (66 FR 
54808, October 30, 2001) and March 18, 2002 (67 FR 40657, June 13, 
2002) (2001 Candidate Assessment, and 2002 Candidate Assessment 
respectively). These assessments are available at http://mountain-prairie.fws.gov/btprairiedog/. In our most recent Notice of Findings on 
Resubmitted Petitions, we noted that we had not yet updated our finding 
with regard to the black-tailed prairie dog (69 FR 24876, May 4, 2004). 
We noted that, since our 2002 assessment, we had received significant 
new information about this species from the NWF, Forest Guardians, and 
the States of Arizona, Colorado, Kansas, Montana, Nebraska, New Mexico, 
North Dakota, Oklahoma, South Dakota, Texas, and Wyoming. We stated 
that we were considering this new information and intended to publish a 
finding for this species upon completing our new assessment. This 
resubmitted 12-month finding is based on consideration of all new 
information that we have received since 2002. It presents evaluations 
of this new information and re-evaluations of previously acquired 
information. In accordance with section 4(b)(3)(B) of the Act, we have 
now completed a status review of the best available scientific and 
commercial information on the species, and have reached a determination 
regarding the petitioned action.

Species Information

    Prairie dogs occur only in North America. They are rodents within 
the squirrel family (Sciuridae) and include five species--the black-
tailed prairie dog; the white-tailed prairie dog (C. leucurus); the 
Gunnison's prairie dog (C. gunnisoni); the Utah prairie dog (C. 
parvidens); and the Mexican prairie dog (C. mexicanus) (Pizzimenti 
1975). The Utah and Mexican prairie dogs are currently listed as 
threatened (49 FR 22339, May 29, 1984) and endangered (35 FR 8495, June 
2, 1970), respectively. Generally, the black-tailed prairie dog occurs 
east of the other four species in more mesic habitat. Based upon the 
information currently available, the Service concurs with Pizzimenti's 
(1975) assessment of the black-tailed prairie dog as monotypic.
    Prairie dogs are small, stout ground squirrels. The total length of 
an adult black-tailed prairie dog is approximately 37 to 43 centimeters 
(14 to 17 inches) and the weight of an individual ranges from 0.5 to 
1.4 kilograms (1 to 3 pounds). Individual appearances within the 
species vary in mixed colors of brown, black, gray, and white. The 
black-tipped tail is characteristic

[[Page 51218]]

(Hoogland 1995). Black-tailed prairie dogs are diurnal, burrowing 
animals. They do not hibernate as do white-tailed, Gunnison's, and Utah 
prairie dogs (Hoogland 1995, Tileston and Lechleitner 1966). The black-
footed ferret (Mustela nigripes), swift fox (Vulpes velox), mountain 
plover (Charadrius montanus), ferruginous hawk (Buteo regalis), 
burrowing owl (Athene cunicularia), and numerous other species are 
dependent upon prairie dogs to varying degrees.
    Several biological factors determine the reproductive potential of 
the species. Females may breed in their first year, but usually do not 
breed until their second year, live 3 to 4 years, and produce a single 
litter, usually four to five pups, annually (Hoogland 1995; Hoogland 
2001; King 1955; Knowles and Knowles 1994). Therefore, 1 female may 
produce 0 to 20 young in its lifetime. While the species is not 
prolific in comparison to many other rodents, the species is capable of 
rapid population increases subsequent to substantial reductions (Seery, 
U.S. Forest Service (USFS), in litt. 2001).
    Historically, black-tailed prairie dogs generally occurred in large 
colonies that contained thousands of individuals, covered hundreds or 
thousands of acres, and extended for miles (Bailey 1905). At present, 
most colonies are much smaller. Colonial behavior offers an effective 
defense mechanism by aiding in the detection of predators and by 
deterring predators through mobbing behavior. It increases reproductive 
success through cooperative rearing of juveniles and aids parasite 
removal via shared grooming. Colonial behavior also can play an 
important role in the transmission of disease (Antolin et al. 2002; 
Biggins and Kosoy 2001; Hoogland 1995; Olsen 1981). The role of 
colonial behavior in the transmission of disease is discussed in more 
detail below (see Factor C).
    Black-tailed prairie dog colonies can combine to form a complex, or 
metapopulation, with interchange occurring between colonies. Typical 
dispersal is usually between established colonies and limited to 
approximately 5 kilometers (3 miles) or less (Garrett and Franklin 
1988, Hoogland 1995); although Knowles (1985) noted occasional long-
distance dispersal distances as high as 10 kilometers (6 miles). Black-
tailed prairie dog complexes or metapopulations expand or contract 
depending upon various intrinsic factors (e.g., reproductive 
capabilities) and extrinsic factors (e.g., chemical control). In order 
to substantially augment or replace populations, several individuals 
must migrate between colonies. However, only a very few individuals are 
required for useful genetic exchange.

Distribution, Abundance, and Trends

    The historic range of the black-tailed prairie dog included 
portions of 11 States, Canada, and Mexico. The species is currently 
present in 10 States--Colorado, Kansas, Montana, Nebraska, New Mexico, 
North Dakota, Oklahoma, South Dakota, Texas, and Wyoming. It has been 
extirpated from Arizona. Black-tailed prairie dogs occur from extreme 
south-central Canada to northeastern Mexico and from approximately the 
98th meridian west to the Rocky Mountains. Range contractions have 
occurred in the southwestern portion of the species' range in Arizona, 
western New Mexico, and western Texas through conversion of grasslands 
to desert shrub lands (Pidgeon et al. 2001). Range contractions are 
largely due to habitat destruction through cropland development in the 
eastern portion of the species' range in Kansas, Nebraska, Oklahoma, 
South Dakota, and Texas (Black-footed Ferret Recovery Foundation, in 
litt. 1999a).
    Populations in Canada represent approximately 0.1 percent of the 
current North American populations. The Committee on the Status of 
Endangered Wildlife in Canada (COSEWIC) has considered the black-tailed 
prairie dog vulnerable since 1978 due to its restricted distribution. 
This status was reconfirmed in 1998 (COSEWIC 1998). Populations in 
Mexico represent approximately 2.7 percent of the current North 
American populations. These populations have been reduced, largely due 
to control efforts and agricultural conversion (Ceballos et al. 1993). 
The species is considered threatened in Mexico (Secretaria del Medio 
Ambiente, Recursos Naturales y Pesca (SEMARNAP) (Environment, Natural 
Resources and Fishing Secretary) 1994).
    Most estimates of prairie dog populations are not based on numbers 
of individual animals, but on estimates of the amount of occupied 
habitat. The actual number of animals present depends upon the 
prevailing density of animals in that locality. Estimates of black-
tailed prairie dog density vary depending upon the season, region, and 
climatic conditions; but typically range from 5 to 45 individuals per 
hectare (2 to 18 individuals per acre) (Fagerstone and Ramey 1996; 
Hoogland 1995; King 1955; Koford 1958; Miller et al. 1996). Density 
also can vary temporally, due to chemical control and plague, as 
discussed in later sections. Most prairie dog surveys do not estimate 
density because of the associated effort and cost. The Service believes 
that estimates of black-tailed prairie dog occupied habitat provide the 
best available and most reasonable means of gauging populations and the 
status of the species across the extensive range of the species.
    Since the 12-month finding in 2000, all States, with the exception 
of Montana, have completed Statewide surveys based on occupied habitat. 
These efforts were systematically designed and implemented, although 
methodologies varied between States. We believe that the current 
Statewide estimates are likely more accurate than those provided in the 
12-month finding, which were largely based on earlier data, 
extrapolation of partial surveys, telephone surveys, and desktop 
exercises. Collectively, the recent estimates represent the first broad 
benchmark of comparison for black-tailed prairie dog populations since 
the early 1960s (Bureau of Sport Fisheries and Wildlife (BSFW) 1961).
    ARIZONA--The black-tailed prairie dog has been extirpated from 
Arizona. No additional information regarding distribution, abundance, 
and trends of the species in Arizona has been obtained since the 12-
month finding.
    COLORADO--The Colorado Division of Wildlife (CDOW) reported a 
Statewide estimate of 256,000 hectares (631,000 acres) of black-tailed 
prairie dog occupied habitat based on an aerial inventory (Pusateri, 
CDOW, in litt. 2002; Russell, CDOW, in litt. 2003). Thirty-eight 
complexes were identified Statewide. The methodology employed by CDOW 
is comprehensive and based on an aerial transect method developed by 
Sidle et al. (2001) and modified by White (CDOW 2003). The Service 
estimate (based upon a sum of site-specific estimates and 
extrapolations) in the 2000 12-month finding was 38,000 hectares 
(93,000 acres) of occupied habitat. The 1961 BSFW estimate was about 
39,000 hectares (96,000 acres). A mail survey estimate reported by 
Colorado Department of Agriculture (1990) was about 394,000 hectares 
(973,000 acres) of occupied habitat.
    The CDOW (2003) identifies 18 extant complexes greater than 2,000 
hectares (5,000 acres). More than 10 percent of the total occupied 
acreage in Colorado occurs in complexes greater than 400 hectares 
(1,000 acres). The most recent inventory indicates that the black-
tailed prairie dog remains widely distributed in Colorado with 100 
percent of the counties within the historic range still containing 
prairie dogs (CDOW 2003).
    Trend information at some Colorado sites indicates declines due to 
plague

[[Page 51219]]

with at least partial recovery in subsequent years. At the Rocky 
Mountain Arsenal, plague has resulted in a substantial overall decline 
in occupied habitat from 250 hectares (1,646 acres) in 2000 to 127 
hectares (314 acres) in 2002 (Seery, Service, in litt. 2002). However, 
at Comanche National Grasslands (NG), occupied habitat appears to have 
returned to pre-plague levels following epizootics. Cully and Johnson 
(2002) estimated 2,382 hectares (5,886 acres) of occupied habitat at 
Comanche NG, a 42 percent increase from 2001. Occupied habitat at 
Pawnee NG in 2002 was reported at about 730 hectares (1,800 acres), a 
65 percent increase from 2001 (Cully and Johnson 2002). Hoefert (U.S. 
Army, in litt. 2002) reported 1,418 hectares (3,500 acres) of occupied 
habitat at Fort Carson, a 109 percent increase from 2001. Estimates for 
Pueblo and Pinon Canyon in 2002 were similar to those in 2001 with 
1,066 hectares (2,632 acres) at Pueblo Army Depot and 143 hectares (353 
acres) at Pinon Canyon Maneuver Site.
    KANSAS--Based on recent aerial surveys, Kansas Department of 
Wildlife and Parks (KDWP) estimated there are about 53,000 hectares 
(130,000 acres) of black-tailed prairie dog occupied habitat in Kansas 
(Mitchener, KDWP, in litt. 2003). The Service estimate (based upon a 
mean of previous estimates) in the 2000 12-month finding was 17,000 
hectares (42,000 acres). The 1961 BSFW estimate was about 20,000 
hectares (50,000 acres).
    There are no extant complexes greater than 2,000 hectares (5,000 
acres) in Kansas. One complex is greater than 400 hectares (1,000 
acres). Less than 10 percent of the total occupied acreage in Kansas 
occurs in complexes greater than 400 hectares (1,000 acres). The black-
tailed prairie dog appears to be largely absent from eastern portions 
of its historic range in Kansas. Nevertheless, more than 75 percent of 
the counties within the historic range of the species contain prairie 
dogs (Luce, Prairie Dog Conservation Team Interstate Coordinator, in 
litt. 2002c).
    For specific sites, Cully and Johnson (2002) estimated 1,344 
hectares (3,321 acres) at Cimarron NG. This was an increase of 26 
percent from 2001.
    MONTANA--The Montana Department of Fish, Wildlife and Parks (MDFWP) 
provided a Statewide estimate (including Tribal lands) of 36,000 
hectares (90,000 acres) of black-tailed prairie dog occupied habitat in 
2002 (Hagener, MDFWP, in litt. 2002). This estimate is the same as that 
in the 2002 candidate assessment. The Service estimate (based upon 
Knowles 1998) in the 2000 12-month finding was 26,000 hectares (65,000 
acres). The 1961 BSFW estimate was about 11,000 hectares (28,000 
acres). In 2003, Hagener (MDFWP, in litt. 2003) noted that most areas 
in Montana show expansion of black-tailed prairie dog occupied habitat.
    There are three extant complexes greater than 2,000 hectares (5,000 
acres). More than 10 percent of the total acreage in Montana occurs in 
complexes greater than 400 hectares (1,000 acres). Black-tailed prairie 
dog populations appear to be widely distributed in Montana with 90 
percent of the historic range occupied by the species (Montana Prairie 
Dog Working Group 2001).
    For specific sites, Vosburgh (Intertribal Consortium, in litt. 
2003) estimated about 3,000 hectares (7,000 acres) of black-tailed 
prairie dog occupied habitat at Crow Reservation in Montana. 
Approximately 80 percent of Reservation lands have been mapped, so the 
actual amount of occupied habitat may be larger. Vosburgh (Intertribal 
Consortium, in litt. 2002) and Hagener (MDFWP, in litt. 2002) both 
noted a 1,200 to 1,600 hectares (3,000 to 4,000 acres) reduction in 
occupied habitat on Crow Reservation lands during 2002 due to plague. 
Both sources also estimated nearly 5,300 hectares (13,000 acres) of 
occupied habitat at Fort Belknap Reservation, a decrease of about 600 
hectares (1,200 acres) from the 1999 estimate due to plague. 
Additionally, Vosburgh (Intertribal Consortium, in litt. 2003) 
estimated 1,585 hectares (3,913 acres) of occupied habitat at the 
Northern Cheyenne Reservation, an increase of about 240 hectares (600 
acres) from the previous estimate in 2002. Hagener (MDFWP, in litt. 
2003) estimated 2,600 hectares (6,300 acres) on Charles M. Russell 
National Wildlife Refuge in 2002. Trend information over the last 10 to 
20 years at most large sites in the State continues to indicate 
declines due to plague, with partial recovery in subsequent years, but 
without complete recovery to pre-plague levels.
    NEBRASKA--Statewide, the Nebraska Game and Parks Commission (NGPC) 
estimated 55,000 hectares (137,000 acres) of black-tailed prairie dog 
occupied habitat in 2003 (Fritz, NGPC, pers. comm. 2004). This estimate 
is derived from aerial surveys employing the same methodology used by 
CDOW. The Service estimate (based upon Amack, NGPC, in litt. 1998 and 
Knowles 1998) in the 2000 12-month finding was 24,000 hectares (60,000 
acres) of occupied habitat. The 1961 BSFW estimate was about 12,000 
hectares (30,000 acres).
    There are no extant complexes greater than 2,000 hectares (5,000 
acres) in Nebraska. One complex is greater than 400 hectares (1,000 
acres). Less than 10 percent of the total occupied acreage in Nebraska 
occurs in complexes greater than 400 hectares (1,000 acres). The black-
tailed prairie dog appears to be largely absent from eastern portions 
of its historic range in Nebraska. Nevertheless, more than 75 percent 
of the counties within the historic range of the species contain 
prairie dogs (Luce, Prairie Dog Conservation Team Interstate 
Coordinator, in litt. 2003).
    For specific sites in Nebraska, 40 hectares (100 acres) of black-
tailed prairie dog occupied habitat were estimated at Enders Wildlife 
Management Area in Chase County and 350 hectares (863 acres) at Oglala 
NG in Sioux County (Fritz, NGPC, in litt. 2002). Thompson (USFS, in 
litt. 2002) provided a more recent estimate for Oglala NG of 516 
hectares (1,275 acres) of occupied habitat. This estimate represents an 
increase of 47 percent from the previous estimate in 2001.
    NEW MEXICO--Based upon evaluations of remote sensing data, about 
24,000 hectares (60,000 acres) of black-tailed prairie dog occupied 
habitat existed Statewide in 2002 (Bell, New Mexico Department of Game 
and Fish (NMDGF), in litt 2002 and Thompson, NMDGF, in litt. 2003). 
Ground-truthing of this estimate is currently under way (Johnson et al. 
2003). The Service estimate (based upon a sum of site-specific 
estimates) in the 12-month finding was 16,000 hectares (39,000 acres) 
of occupied habitat. The 1961 BSFW estimate was about 7,000 hectares 
(17,000 acres).
    There are no extant complexes greater than 400 hectares (1,000 
acres) in New Mexico. The black-tailed prairie dog appears to be 
largely absent from western portions of its historic range in New 
Mexico. Nevertheless, more than 75 percent of the counties within the 
historic range of the species contain prairie dogs (Luce, Prairie Dog 
Conservation Team Interstate Coordinator, in litt. 2002c).
    For specific sites, the U.S. Army provided an estimate of 130 
hectares (330 acres) of black-tailed prairie dog occupied habitat at a 
Fort Bliss facility in New Mexico (Hoefert, U.S. Army, in litt. 2002). 
This estimate is the same as that reported in 2001.
    NORTH DAKOTA--Based upon aerial surveys and ground-truthing, a 
minimum of 8,000 hectares (20,000 acres) of black-tailed prairie dog 
occupied habitat existed Statewide (including on Tribal lands) in 2003 
(McKenna, NDGFD, in litt. 2003). The

[[Page 51220]]

Service estimate (based upon Sidle, USFS, pers. comm. 1999) in the 12-
month finding was 10,000 hectares (25,000 acres) of occupied habitat. 
The 1961 BSFW estimate was about 8,000 hectares (20,000 acres).
    North Dakota has the smallest recent State-occupied habitat 
estimate with about 8,000 hectares (20,000 acres) in 540 active 
colonies (Knowles 2003). Knowles (2003) describes two complexes or 
metapopulations--one being connected to metapopulations in South 
Dakota, and the other quite disjunct from other populations. According 
to Luce (Prairie Dog Conservation Team Interstate Coordinator, in litt. 
2003), there are no extant complexes greater than 2,000 hectares (5,000 
acres) in North Dakota. One complex is greater than 400 hectares (1,000 
acres), but less than 10 percent of the total occupied acreage in North 
Dakota occurs in complexes greater than 400 hectares (1,000 acres). 
Black-tailed prairie dog populations appear to be widely distributed in 
North Dakota with 81 percent of the counties within the historic range 
of the species containing prairie dogs (Knowles 2003).
    For specific sites, 117 hectares (290 acres) of black-tailed 
prairie dog occupied habitat were estimated at Fort Berthold 
Reservation, following mapping in 2003 (Vosburgh, Intertribal 
Consortium, in litt. 2003). There was an estimated 821 hectares (2,026 
acres) of occupied habitat on the Little Missouri NG (Luce, Prairie Dog 
Conservation Team Interstate Coordinator, in litt. 2003).
    OKLAHOMA--Based upon aerial surveys, the Oklahoma Department of 
Wildlife Conservation (ODWC) estimated 26,000 hectares (64,000 acres) 
of black-tailed prairie dog occupied habitat Statewide in 2003 
(Hoagland, ODWC, pers. comm. 2003). Approximately 50 percent of the 
area has been ground-truthed to date, with 15,700 hectares (38,700 
acres) verified as active (Duffy, ODWC, in litt. 2003). The Service 
estimate (based upon Lomolino and Smith 2001) in the 12-month finding 
was 3,600 hectares (9,000 acres) of occupied habitat. The 1961 BSFW 
estimate was about 6,000 hectares (15,000 acres).
    There do not appear to be any complexes greater than 400 hectares 
(1,000 acres) in Oklahoma. The black-tailed prairie dog appears to be 
largely absent from eastern portions of its historic range in Oklahoma. 
Nevertheless, more than 75 percent of the counties within the historic 
range of the species contain prairie dogs (Luce, Prairie Dog 
Conservation Team Interstate Coordinator, in litt. 2002c).
    For specific sites, 5,477 hectares (13,523 acres) of black-tailed 
prairie dog occupied habitat were estimated to exist in Cimarron County 
(Luce, Prairie Dog Conservation Team Interstate Coordinator, in litt. 
2002b).
    SOUTH DAKOTA--In 2003, a partial estimate was provided for South 
Dakota of more than 81,000 hectares (200,000 acres) of black-tailed 
prairie dog occupied habitat, including Tribal lands (Cooper and 
Gabriel, South Dakota Department of Game, Fish, and Parks (SDDGFP) and 
South Dakota Department of Agriculture, in litt. 2004). Subsequently, a 
draft management plan was released that estimated, based on aerial 
surveys, 165,000 hectares (407,000 acres) of black-tailed prairie dog 
occupied habitat Statewide (South Dakota Department of Agriculture and 
SDDGFP 2004). This included an estimated 87,000 hectares (215,000 
acres) of occupied habitat on Tribal lands and 78,000 hectares (192,000 
acres) on non-Tribal lands. The Service estimate (based upon Sidle, 
USFS, pers. comm. 1999) provided in the 2000 12-month finding was 
60,000 hectares (147,000 acres) of occupied habitat. The 1961 BSFW 
estimate was about 13,000 hectares (33,000 acres).
    There are four extant complexes greater than 2,000 hectares (5,000 
acres). More than 10 percent of the total acreage in South Dakota 
occurs in complexes greater than 400 hectares (1,000 acres). The black-
tailed prairie dog appears to be widely distributed in South Dakota 
with at least 91 percent of the counties within the historic range of 
the species containing prairie dogs (South Dakota Department of 
Agriculture and SDDGFP 2004).
    For specific sites, 1,900 hectares (4,800 acres) of black-tailed 
prairie dog occupied habitat were mapped at Badlands National Park in 
2002 (Albertson, National Park Service (NPS), in litt. 2002) and 2,300 
hectares (5,600 acres) in 2003 (Albertson, NPS, in litt. 2003). This 
represents a 17 percent increase from 2002 to 2003. Turner Endangered 
Species personnel estimated 584 hectares (1,443 acres) of occupied 
habitat at Bad River Ranch in 2003 (Bly Honness, Turner Endangered 
Species Fund, in litt. 2003), an 11 percent increase from 2002. 
Morgenstern (Ellsworth Air Force Base, in litt. 2003) reported 38 
hectares (95 acres) of occupied habitat on Ellsworth Air Force Base and 
320 hectares (800 acres) on the Badlands Bomb Range in 2003. The Lower 
Brule Sioux Tribe estimated 1,190 hectares (2,940 acres) of occupied 
habitat in 2003 (Lewis, Lower Brule Sioux Tribe, in litt. 2003). 
Newspaper interviews of Tribal representatives reported approximately 
40,500 hectares (100,000 acres) of occupied habitat at Pine Ridge/
Oglala Sioux Reservation and 20,250 hectares (50,000 acres) of occupied 
habitat at Rosebud Sioux Reservation in 2003 (Miller 2004). The South 
Dakota Black-Tailed Prairie Dog Management Plan estimates approximately 
36,000 hectares (89,000 acres) of occupied habitat at Pine Ridge/Oglala 
Sioux Reservation and approximately 16,000 hectares (39,000 acres) of 
occupied habitat at Rosebud Sioux Reservation in 2004 (South Dakota 
Department of Agriculture and SDDGFP 2004). Thompson (USFS, in litt. 
2002) estimated 7,327 hectares (18,105 acres) of occupied habitat at 
Buffalo Gap NG, 260 hectares (642 acres) at Fort Pierre NG, and 723 
hectares (1,787 acres) at Grand River NG in 2002.
    TEXAS--The Texas Parks and Wildlife Department (TPWD) provided a 
preliminary Statewide estimate in 2002 of 96,000 hectares (236,000 
acres) of black-tailed prairie dog occupied habitat based upon 1996-97 
digital ortho-photo quadrangle interpretation (Young, TPWD, in litt. 
2002). The TPWD proposed to review 2003 satellite imagery for select 
counties to determine any changes in occupied habitat from 1996-97 to 
2003. Ground-truthing has been completed for 70 out of 78 counties for 
a current minimum of 72,000 hectares (178,000 acres) of occupied 
habitat (Holdstock, TPWD, in litt. 2003). The Service estimate 
(modified from Cheatheam 1977) in the 2000 12-month finding was 29,000 
hectares (71,000 acres) of occupied habitat. The 1961 BSFW estimate was 
about 11,000 hectares (26,000 acres).
    There are no extant complexes greater than 400 hectares (1,000 
acres) in Texas. The black-tailed prairie dog appears to be distributed 
throughout most of its historic range in Texas. More than 75 percent of 
the counties within the historic range of the species contain prairie 
dogs (Luce, Prairie Dog Conservation Team Interstate Coordinator, in 
litt. 2002c).
    For specific sites, about 284 hectares (700 acres) of occupied 
habitat were estimated at the City of Lubbock Land Application Site 
(Fuquay 2004). County estimates are under development by the TPWD.
    WYOMING--Luce (Prairie Dog Conservation Team Interstate 
Coordinator, in litt. 2003) estimated 51,000 hectares (125,000 acres) 
of black-tailed prairie dog occupied habitat Statewide in 2003. This 
estimate is equal to the Service estimate (based upon a projected 
decline from Wyoming Game and Fish Department's (WGFD)

[[Page 51221]]

1987 estimate) in the 12-month finding. The 1961 BSFW estimate was 
about 20,000 hectares (49,000 acres). The WGFD is currently mapping 
towns from 2001 color infrared aerial photos and field checking a 
significant portion of the towns mapped (Rothwell, WGFD, in litt. 
2003).
    There is one extant complex greater than 2,000 hectares (5,000 
acres) in Wyoming. We are unaware of any additional complexes greater 
than 400 hectares (1,000 acres). It appears that less than 10 percent 
of the total occupied acreage in Wyoming occurs in complexes greater 
than 400 hectares (1,000 acres). The black-tailed prairie dog appears 
to be widely distributed throughout most of its historic range in 
Wyoming. More than 75 percent of the counties within the historic range 
of the species contain prairie dogs (Luce, Prairie Dog Conservation 
Team Interstate Coordinator, in litt. 2002c).
    Plague has resulted in notable declines in the State's largest 
identified complex at Thunder Basin NG. Thunder Basin NG was estimated 
to contain about 3,600 hectares (9,000 acres) of occupied habitat in 
2003 following a plague epizootic (Byer, USFS, pers. comm. 2003). 
Approximately 7,300 hectares (18,000 acres) of occupied habitat existed 
in 2000 prior to plague (Thompson, USFS, in litt. 2002). Another way to 
evaluate the impacts of plague at this site is to examine the number of 
colonies impacted. In 2002, the WGFD reported that only 11 percent of 
the colonies surveyed at Thunder Basin NG were still active (Wichers, 
WGFD, in litt. 2002).
    For other specific sites, the U.S. Army provided an estimate of 280 
hectares (700 acres) of black-tailed prairie dog occupied habitat at 
the Sheridan Training Area in 2002 (Hoefert, U.S. Army, in litt. 2002). 
This was the same as the estimate provided in 2001. Cheatham (NPS, in 
litt. 2003) reported 16 hectares (40 acres) of occupied habitat at 
Devils Tower National Monument in 2003.
    CANADA--No new estimates of black-tailed prairie dog occupied 
habitat have been provided since 2001. The most recent estimate is 
1,049 hectares (2,589 acres) of occupied habitat (Fargey, Grasslands 
National Park, in litt. 2001). This estimate is similar to the Service 
estimate in the 12-month finding of 800 hectares (2,000 acres) of 
occupied habitat, all at Grasslands National Park in Saskatchewan. In 
general, population estimates of the black-tailed prairie dog in Canada 
appear to be stable, but small.
    MEXICO--No new estimates of black-tailed prairie dog occupied 
habitat have been provided since 2001. The most recent estimate is more 
than 20,000 hectares (49,000 acres) of occupied habitat, almost all of 
it at one site near Janos, Chihuahua (List in litt. 2001). The Service 
estimate in the 12-month finding was 36,000 hectares (90,000 acres) of 
occupied habitat. List (in litt. 2001) also noted that 1,170 hectares 
(2,889 acres) of occupied habitat had been lost (50 percent of that due 
to conversion of rangeland to cropland), but that the large difference 
from earlier estimates for the site was due to earlier mapping errors 
and did not represent an actual loss of occupied habitat. In general, 
population estimates of the black-tailed prairie dog in Mexico appear 
to be stable in recent decades. The species appears to be absent from 
much of its historic range in Mexico.
    State agencies now estimate approximately 745,400 hectares 
(1,842,000 acres) of occupied habitat across the United States as 
opposed to an estimate of 364,000 acres in 1961. As noted above, 
evaluation of prairie dog population status is based on amount of 
occupied habitat, not numbers of individual animals. However, many 
people are interested in the estimated numbers of prairie dogs. 
Estimates of black-tailed prairie dog density typically range from 
between 2 to 18 animals per acre, with an average of 10 per acre. 
Applying these density estimates to the acreage figures generates an 
estimated population of black-tailed prairie dogs ranging between 
3,684,000 and 33,156,000, with the average density figure yielding an 
estimated population of 18,420,000 black-tailed prairie dogs in the 
United States. This estimate of the abundance of the black-tailed 
prairie dog has implications for our analysis of the threats faced by 
the black-tailed prairie dog described below.

Discussion of Listing Factors

    Section 4 of the Act (16 U.S.C. 1533) and implementing regulations 
at 50 CFR part 424 set forth procedures for adding species to the 
Federal List of Endangered and Threatened Wildlife. A species may be 
determined to be an endangered or threatened species due to one or more 
of the five factors described in section 4(a)(1). These factors and 
their application to black-tailed prairie dog are evaluated below.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    In the 2000 12-month finding, we concluded that effects due to the 
present or threatened destruction, modification, or curtailment of 
habitat or range were a moderate, imminent threat. No changes regarding 
the magnitude or immediacy of threat from this factor were made in our 
assessment of the species and resubmitted petition finding in 2001 (66 
FR 54808, October 30, 2001). Our 2002 assessment and resubmitted 
petition finding (67 FR 40657, June 13, 2002) addressed habitat threats 
individually. We concluded that the present or threatened destruction 
of habitat from agricultural conversion and other factors was no longer 
a threat. We concluded that the present or threatened modification of 
habitat due to the presence of plague was a moderate, imminent threat. 
We concluded that the present curtailment of habitat due to chemical 
control was no longer a threat and the threatened curtailment of 
habitat was a low magnitude, non-imminent threat.
    Historically as many as 40 million hectares (100 million acres) of 
occupied black-tailed prairie dog colonies occurred across a landscape 
of approximately 162 million hectares (400 million acres) of potential 
habitat (Black-footed Ferret Recovery Foundation, in litt. 1999a; 
Fagerstone and Ramey 1996; Knowles 1998; Seton 1953). At present, there 
are an estimated 745,400 hectares (1,842,000 acres) of occupied habitat 
in the United States. Habitat destruction resulted from cropland 
development, urbanization, changes in vegetative communities, burrow 
deterioration, and fragmentation. The most substantial cause of habitat 
destruction that we are able to quantify is cropland development. 
Conversion of the native prairie to cropland has largely progressed 
across the species' range from east to west, with the more intensive 
agricultural use in the eastern portion of the species' range. Black-
tailed prairie dog use of potential habitat is somewhat, but not 
completely, limited by this conversion. Approximately 37 percent of the 
suitable habitat within its range has been converted to cropland uses 
(Black-footed Ferret Recovery Foundation, in litt. 1999b). However, the 
12-month finding noted that the current threat of habitat loss through 
cropland conversion is much less than in the early days of agricultural 
development in the Great Plains and that a considerable amount of 
potential unoccupied habitat remains.
    The Natural Resources Conservation Service quantified land cover/
land use changes from 1982 to 1997 (U.S. Department of Agriculture 
2000). The 11 States within the historic range of the black-tailed 
prairie dog experienced a 10 percent loss of cropland and a 2 percent 
loss of rangeland during this

[[Page 51222]]

time period. However, when the amount of current occupied habitat is 
contrasted with the amount of remaining rangeland (potential habitat), 
estimated in the hundreds of millions of acres, it is evident that 
sufficient potential habitat still occurs in each of the 11 States 
within the historic range of the species to accommodate large 
expansions of black-tailed prairie dog populations (U.S. Department of 
Agriculture 2000). This conclusion is supported by Sidle et al. (2001), 
who noted that, although substantial areas of grassland have been 
converted to cropland in the northern Great Plains, vast areas of 
suitable habitat for colonization and expansion of black-tailed prairie 
dogs remain.
    Rosmarino (Forest Guardians et al., in litt. 2003a and 2003b) 
expressed concern regarding the substantial loss of habitat due to 
urbanization along the Colorado Front Range. We acknowledge that 
urbanization is an ongoing factor in habitat loss along the Front 
Range. In the 12-month finding, we noted that urbanization represents a 
locally substantial loss of occupied habitat, but in a range-wide 
context it is not significant. We continue to believe that, given 
population estimates in Colorado and elsewhere, urbanization cannot be 
considered a threat at present or in the foreseeable future, either in 
Colorado or rangewide.
    Gilpin (University of California, in litt. 2001) considered habitat 
fragmentation, which decreases colony and metapopulation size, a 
serious threat that could impact future viability of the black-tailed 
prairie dog. However, Luce (Prairie Dog Conservation Team Interstate 
Coordinator, in litt. 2002c) suggested that fragmentation of habitat 
and scattered distribution may have isolated black-tailed prairie dog 
populations and prevented plague from impacting them. He noted that it 
is important to recognize the presence and value of ``small, remnant 
populations.'' This issue is more thoroughly discussed under Factor C.
    We continue to conclude that present or threatened habitat 
destruction is not a threat to the species, although considerable 
effects due to this factor have occurred in the past. Additionally, we 
now conclude that present or threatened habitat modification as it 
relates to plague is not a significant threat to the species given the 
analysis that follows under Factor C. Threatened habitat curtailment as 
it relates to chemical control is not a significant threat to the 
species given the analysis that follows under Factor E.

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

    In the 2000 12-month finding, we concluded that effects due to 
scientific or educational purposes and commercial use of the species 
via the pet trade were not threats to the species. These conclusions 
were reaffirmed in our assessments of the species in 2001 and 2002. We 
continue to believe these factors are not threats pursuant to the 
definitions of the Act.
    The 2000 12-month finding also concluded that recreational shooting 
could be a low, imminent threat in some circumstances. No changes 
regarding the magnitude or immediacy of threat from this factor were 
made in our 2001 Candidate Assessment. In the 2002 Candidate Assessment 
we determined that recreational shooting did not rise to the level of a 
threat to the species.
    Knowles (2003) noted extensive recreational shooting in North 
Dakota, but found no clear evidence that shooting controlled prairie 
dog populations. Rosmarino (Forest Guardians et al., in litt. 2003a and 
2003b) suggested that density is reduced, that small colonies have been 
extirpated by shooting, and that larger colonies could be reduced. 
Reeve and Vosburgh (in draft) concluded that interest in and intensity 
of recreational shooting has increased dramatically over the past 
decade and that shooting can cause changes in prairie dog behavior and 
reproductive success. However, they also noted that prairie dog 
populations are capable of recovering from shooting.
    Some of the States with substantial amounts of public lands are 
experiencing greater shooting pressure on prairie dogs in some areas 
than previously estimated, and are implementing regulations to better 
monitor and control this activity. These regulations are described 
under Factor D.
    We are aware that recreational shooting can reduce black-tailed 
prairie dog population densities at specific sites, and acknowledge the 
possibility that extirpation may have occurred in isolated 
circumstances (Knowles 1988), but we believe black-tailed prairie dog 
populations can recover from very low numbers following intensive 
recreational shooting (Knowles 1988, Reeve and Vosburgh in draft). 
Therefore, we continue to conclude that effects due to recreational 
shooting do not rise to the level of a threat pursuant to the 
definitions of the Act. Recent Statewide and range-wide estimates of 
occupied habitat further reinforce this conclusion.

C. Disease or Predation

    In the 2000 12-month finding, we concluded that predation was not a 
threat. This conclusion was reaffirmed in our 2001 and 2002 Candidate 
Assessments. We continue to believe this factor is not a threat 
pursuant to the definitions of the Act.
    The 2000 12-month finding concluded that disease was a moderate, 
imminent threat. No changes regarding the magnitude or immediacy of 
threat from disease were made in our 2001 or 2002 assessments.
    Although plague is likely the most important factor adversely 
influencing black-tailed prairie dogs, recent information indicates the 
populations are not as vulnerable to the disease as previously thought. 
Plague is an exotic disease foreign to the evolutionary history of 
North American species. It is caused by the bacterium Yersinia pestis, 
which fleas acquire from biting infected animals and can then transmit 
via a bite to other animals. The disease also can be transmitted 
pneumonically directly among infected animals. Some rodent species may 
act as carriers of the disease or infected fleas with little or no 
symptoms. Black-tailed prairie dogs cannot be considered carriers 
because of their high mortality rate (Barnes 1993, Cully and Williams 
2001).
    Plague was first observed in wild rodents in North America near San 
Francisco, California, in 1908 (Eskey and Haas 1940). The first 
reported incidences of plague in black-tailed prairie dogs occurred in 
the 1940s (Gage, Center for Disease Control, pers. comm. 1999, Miles et 
al. 1952). Evidently, plague spread from the west coast to its present 
easterly limit in about 50 years. Plague is currently limited to the 
western two-thirds of the black-tailed prairie dog range (perhaps due 
to some unknown ecological limitations) (Barnes 1993). Black-tailed 
prairie dog habitat in all of Montana, Wyoming, Colorado, New Mexico, 
and Arizona is impacted by plague. Portions of western North Dakota, 
Nebraska, Kansas, Oklahoma, and Texas have records of plague in black-
tailed prairie dogs. Black-tailed prairie dog habitat in the eastern 
portions of these same States and all of South Dakota are free of 
plague.
    The major effects of plague on black-tailed prairie dogs are to 
reduce colony size, increase variance in colony populations, and 
increase inter-colony distances within complexes (Brand 2002). Recently 
documented plague outbreaks include Bent County, Fort Carson, Pinon 
Canyon, and Rocky Mountain Arsenal in Colorado; Crow

[[Page 51223]]

and Fort Belknap Reservations in Montana; Kiowa NG and Rita Blanca NG 
in Texas and Oklahoma; and Thunder Basin NG in Wyoming. The plague 
epizootic at Thunder Basin was particularly notable because the 
location was one of the few remaining complexes greater than 4,000 
hectares (10,000 acres), and the epizootic brought plague close to some 
of the last remaining large plague-free complexes found in South 
Dakota.
    In our 2000 12-month finding, we focused attention on a few large 
black-tailed prairie dog populations impacted by plague and 
extrapolated population losses at these sites across the species' 
entire range. Based on generally accepted conservation biology 
principles (Gilpin and Soule 1986; Hanski and Gilpin 1997; MacArthur 
and Wilson 1967; Miller et al. 1996; Shaffer 1981; Wilcove et al. 1986; 
and Wilcox and Murphy 1985), we presumed that smaller black-tailed 
prairie dog populations had been and would be similarly or more 
adversely impacted. An approximate 50 percent decline per decade was 
predicted for the foreseeable future. Much better information is now 
available. Given recent population estimates across a majority of the 
species' range, it appears the previously hypothesized projections were 
invalid. While occupied habitat at specific large complexes may 
experience dramatic fluctuations due to plague epizootics, they do not 
appear to be influencing the species' range-wide persistence.
    Recent data indicate that, in some portions of the species' range, 
some colonies recover and may approach pre-plague population levels 
following plague epizootics. At Comanche NG in Colorado, approximately 
1,820 hectares (4,500 acres) of black-tailed prairie dog occupied 
habitat were estimated to exist on the Carrizo Unit of Comanche NG in 
1995. In 1996, all of the towns inspected had experienced total or near 
total extirpation. No fleas were collected to facilitate plague 
surveillance, but the pattern of widespread elimination of prairie dog 
colonies was the pattern expected from sylvatic plague. Plague was 
documented the following year in a nearby colony. In 1998, 
approximately 200 hectares (500 acres) of occupied habitat were found 
on the grassland's Carrizo Unit (Cully 1998). Data are not available 
from the Carrizo Unit for subsequent years, but throughout the entire 
Comanche NG, 560 hectares (1,374 acres) of occupied habitat were 
present in 1998 (Sidle, USFS, in litt. 1999). Occupied habitat at 
Comanche NG increased to 800 hectares (1,974 acres) in 1999 (Thompson, 
USFS, in litt. 2002), 1,760 hectares (4,342 acres) in 2001 (Cully and 
Johnson 2002), and 2,380 hectares (5,886 acres) in 2002 (Cully and 
Johnson 2002). Cully and Johnson (2002) noted that ``colony area on the 
Comanche NG is similar to what was present before the die-off there in 
1994-95.''
    At Cimarron NG in Kansas, plague was documented in 1949, 1997, and 
1999 (Cully and Williams 2001). Nevertheless, populations appear to be 
increasing in recent years, with occupied habitat estimates of 520 
hectares (1,287 acres) in 1998 (Sidle, USFS, in litt. 1999), 680 
hectares (1,688 acres) in 1999 (Thompson, USFS, in litt. 2002), 1,070 
hectares (2,639 acres) in 2001 (Thompson, USFS, in litt. 2002) and 
1,345 hectares (3,321 acres) in 2002 (Cully and Johnson 2002). Cully 
and Johnson (2002) noted that ``colony area on the Cimarron NG is the 
highest ever recorded.'' Other examples of population recovery are 
discussed in the Distribution, Abundance, and Trends section of this 
document. The severity of plague outbreaks may vary, with severe 
outbreaks and limited recovery occurring at some complexes (Rocky 
Mountain Arsenal, Colorado, and Ft. Belknap and Northern Cheyenne 
Reservations in Montana) and less severe outbreaks with apparently 
complete or near complete recovery at other sites (Cimarron NG and 
Comanche NG).
    Recent laboratory research indicates that at low levels of exposure 
a small percentage of black-tailed prairie dogs show some immune 
response and consequently some resistance to plague (Rocke, U.S. 
Geological Survey (USGS), pers. comm. 2002), similar to what has been 
reported in Gunnison's (Cully et al. 1997) and white-tailed prairie 
dogs (Biggins, USGS, pers. comm. 2002). The Center for Disease Control 
recently reported that seroconversion (evidence of some immune 
response) occurred in 2 out of 65 black-tailed prairie dogs collected 
following a plague event at Pawnee NG in Colorado (Antolin, Colorado 
State University, pers. comm. 2002). Nevertheless, an individual black-
tailed prairie dog exposed to plague is at high risk due to a 
combination of low resistance and high sociality (Biggins and Kosoy 
2001).
    It has been suggested that the responses of black-tailed prairie 
dog populations to plague may vary based on their population density 
(Cully, USGS, pers. comm. 2002). The likelihood of plague transmission 
in prairie dogs from flea bites versus pneumonically from other prairie 
dogs already infected is unknown, but is being investigated. It may be 
that survival of some individuals in low-density or isolated 
populations is facilitated by the necessity of high exposure rates for 
individuals to contract the disease. Single or even multiple flea bites 
do not always have a high enough dose for infection to occur (Rocke, 
USGS, pers. comm. 2002). In contrast, if plague is spread pneumonically 
from animal to animal, a much larger dose is transferred than from a 
flea bite. In such situations, the impact on a large, densely populated 
complex could be substantial. A population dynamic may have developed 
that somewhat protects low density, isolated black-tailed prairie dog 
populations from extirpation, even with infected fleas resident in the 
habitat of surviving prairie dogs.
    Lomolino et al. (2003) postulated that habitat fragmentation may 
benefit some prairie dog populations by protecting them from plague 
through isolation. Historically, black-tailed prairie dogs were 
typically found in large complexes that consisted of many colonies that 
were close enough to each other to allow frequent dispersal between 
colonies. Currently, due to a combination of factors including habitat 
fragmentation, plague, and poisoning, many prairie dogs exist in much 
smaller complexes or in isolated colonies where the possibility for 
interchange is reduced. Smaller populations also may be protected by 
limiting exposure via direct animal-to-animal contact (Cully and 
Williams 2001, Roach et al. 2001). Influences other than plague likely 
will still adversely affect small black-tailed prairie dog populations, 
but they have not been demonstrated to be as serious as plague.
    Trudeau (2002) noted that ``sylvatic plague epizootics have the 
potential to cause severe population bottlenecks in black-tailed 
prairie dog colonies contributing to losses of alleles and decreases in 
heterozygosity. Plague could potentially devastate genetic variability 
in affected prairie dog colonies, causing inbreeding depression in the 
short-term and inability to adapt to environmental change in the long-
term.'' However, the author also noted that ``even though a significant 
reduction in heterozygosity was observed in plagued colonies, gene flow 
may balance the effects of the sylvatic plague by reintroducing levels 
of variation in genetically depauperate post-plague colonies. * * * 
Given time, gene flow should erase the effects of plague on genetic 
variability assuming that colonies receive an adequate number of 
migrants to reintroduce genetic variability and population size is 
stable following recovery.'' Roach et al. (2001) noted that extinction 
and

[[Page 51224]]

recolonization by black-tailed prairie dogs in the presence of plague 
has not increased genetic differentiation among prairie dog colonies in 
north-central Colorado. Dispersal has been adequate to prevent genetic 
isolation.
    In 2003, monkeypox was detected in pet prairie dogs in Wisconsin, 
Illinois, and Indiana. The source of the infection was a shipment of 
rodents from Africa. The disease was never found in any wild prairie 
dogs or other wild rodents (Center for Disease Control 2003). 
Consequently, we do not consider this disease to be a threat to black-
tailed prairie dogs.
    We continue to conclude that effects on black-tailed prairie dog 
populations due to predation are not a threat to the persistence of the 
species. Our previous conclusions regarding the perceived effects of 
plague on the persistence of the species have been altered by 
information indicating that--(1) High exposure doses of plague bacilli 
may be necessary for disease contraction in some individuals; (2) 
limited immune response has been observed in some individuals; (3) a 
population dynamic may have developed in low-density, isolated 
populations that contributes to the persistence of these populations; 
(4) the apparent ability of some sites to recover to pre-plague levels 
after a plague epizootic; and (5) approximately one-third of the 
species' historic range has not been affected by plague. Based on both 
the new information above and recent State-by-State range-wide 
estimates of occupied habitat that indicate species abundance, plague 
no longer appears to be as significant a threat as previously thought. 
We predict that plague will continue to influence black-tailed prairie 
dog population dynamics to a degree. However, we now conclude that 
plague in combination with other factors is not likely to cause the 
black-tailed prairie dog to become an endangered species within the 
foreseeable future.

D. The Inadequacy of Existing Regulatory Mechanisms

    In the 2000 12-month finding, we concluded that the inadequacy of 
existing regulatory mechanisms was a moderate, imminent threat. No 
changes regarding the magnitude or immediacy of threat from this factor 
were made in our 2001 Candidate Assessment. In our 2002 Candidate 
Assessment, the threats due to inadequate regulatory mechanisms were 
addressed separately as they related to habitat curtailment, 
recreational shooting, disease, and chemical control. The regulatory 
concerns as they pertained to recreational shooting were not considered 
a threat (since regulatory shooting was not considered a threat). The 
regulatory concerns as they pertained to chemical control were 
considered low, non-imminent threats. The regulatory concerns as they 
pertained to disease were considered a moderate, non-imminent threat.
    In this finding we have addressed the regulatory concerns as they 
relate to disease in factor C. We have discussed chemical control under 
factor E, and we have dealt with recreational shooting under factor B. 
We have found disease to be a low-level, non-imminent threat, chemical 
control not to be a threat, and recreational shooting not to be a 
significant threat. 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.
    We have considered the current status of State, Tribal, and Federal 
regulatory mechanisms, as well as any proposed changes. A description 
of these regulatory measures with a specific focus on recreational 
shooting, chemical control, and management goals designed to ameliorate 
the influences of plague and other lesser impacts is included in the 
revised candidate assessment.
    During the past few years some States and Tribes have made 
substantial progress in initiating management efforts for the black-
tailed prairie dog, including completing surveys to provide more 
accurate estimates of occupied habitat, drafting management plans, 
enacting laws that change the status of the species from pest to a 
designation that recognizes the need for management, establishing 
regulations that allow for better management of recreational shooting, 
and setting future goals for occupied habitat that will address 
population management needs for disease and other threats. While these 
efforts are important to black-tailed prairie dog management, the 
distribution, abundance, and trends data indicate that inadequate 
regulatory mechanisms are not limiting black-tailed prairie dog 
populations at present, nor are they likely to within the foreseeable 
future. Therefore, we now conclude that these concerns do not rise to 
the level of a threat.

E. Other Natural or Manmade Factors Affecting the Continued Existence 
of the Species

    We consider chemical control of black-tailed prairie dogs and 
synergistic effects from all threats under this factor. Chemical 
control also is influenced by adequacy of regulatory mechanisms.
    In the 2000 12-month finding we concluded that both chemical 
control and synergistic effects were moderate, imminent threats. No 
changes regarding the magnitude or immediacy of threat from this factor 
were made in the 2001 Candidate Assessment. In the 2002 Candidate 
Assessment we concluded that chemical control was a moderate, non-
imminent threat. We concluded that synergistic effects likely impact 
the species; however, we were unable to quantify those effects and 
consequently described the effects as not a threat due to a lack of 
information.
    Organized prairie dog control from 1916 to 1920 included the 
poisoning of tens of millions of acres of western rangeland (Bell 
1921). From 1937 to 1968, 12,331,178 hectares (30,447,355 acres) of 
prairie dog occupied habitat were controlled (Cain et al. 1972). Of the 
lands controlled from 1937 to 1968, 75 percent were treated by 1950, 
with an average of more than 650,000 hectares (1.6 million acres) 
treated annually. From 1951 to 1968, the average amount of prairie dog 
occupied habitat controlled annually decreased to approximately 174,000 
hectares (430,000 acres) per year. In the 1960s, several States reached 
their lowest estimates of black-tailed prairie dog occupied habitat. 
According to Cain et al. (1972), in the late 1960s the public became 
interested in Federal animal control programs, including prairie dog 
control, and this interest resulted in increased attention to 
ecological considerations. Several toxicants previously used for pest 
or predator control were banned. In 1972, Compound 1080, which was used 
extensively in early prairie dog control efforts, was banned by 
Presidential Executive Order 11643 for use on Federal lands, in Federal 
programs, or on private lands (Barko 1997). Although prairie dog 
control continued via other toxicants (zinc phosphide), it was at a 
reduced rate and with less effective poisons that required pre-baiting.
    The last large-scale chemical control effort for black-tailed 
prairie dogs occurred on the Pine Ridge/Oglala Sioux Reservation in 
South Dakota in the 1980s. This effort resulted in the eradication of 
most prairie dogs on approximately 185,740 hectares (458,618 acres) of 
occupied habitat from 1980 to 1984. From 1985 to 1986, 97,000 hectares 
(240,000 acres) were re-treated (Roemer and Forrest 1996). Estimates of 
occupied habitat have increased at Pine Ridge/Oglala Sioux Reservation 
from approximately 8,000 to 12,000 hectares (20,000 to 30,000 acres) in 
1999 (Yellowhair, Pine Ridge Sioux Tribe, pers. comm. 1999) to 
approximately 36,000 to 40,000 hectares (89,000 to 100,000 acres) in 
2003 (South Dakota

[[Page 51225]]

Department of Agriculture and SDDGFP 2004; Miller 2004). Following 
control efforts on Pine Ridge, three additional extensive control 
efforts targeted for the Cheyenne River Sioux and Rosebud Sioux 
Reservations in South Dakota and Fort Belknap Reservation in Montana 
were halted due to concerns regarding the lack of available black-
footed ferret reintroduction sites.
    The potential for future large-scale control efforts on Tribal 
lands may affect the black-tailed prairie dog in South Dakota. The BIA 
is currently considering some chemical control of rapidly expanding 
colonies on Tribal lands. Black-tailed prairie dog populations at 
several of these sites are the last remaining large complexes (greater 
than 4,000 hectares/10,000 acres) that have not experienced plague. The 
suggested intent of these proposed efforts would be to control some 
prairie dogs, particularly where they encroach on private lands, but 
allow core areas that are suitable for potential black-footed ferret 
reintroduction efforts to remain intact. This approach is more flexible 
and much less problematic than historic attempts to completely 
extirpate populations. As noted earlier, the most recent estimate of 
occupied habitat for South Dakota for 2003 was 165,000 hectares 
(407,000 acres) with approximately 87,000 hectares (215,000 acres) 
occurring on tribal lands.
    Recent chemical control efforts have often been less successful 
than historic efforts for a variety of reasons. Early chemical control 
efforts were well-funded, federally-directed efforts that utilized 
efficient toxicants. Many current control efforts are small-scale, 
privately funded and privately directed efforts. The result is 
localized effects without significant impacts on population dynamics 
range wide. Available chemicals also are less effective than early 
toxicants that are now banned.
    It is difficult to obtain accurate information regarding the use of 
toxicants to control black-tailed prairie dogs. The Environmental 
Protection Agency, the Federal agency responsible for establishing 
labeling requirements on all pesticides, has been unable to provide any 
information regarding distribution or use. They have noted that 
distribution and sale of a proprietary pesticide is considered 
confidential trade information and cannot be disclosed except in 
unusual circumstances. They also note that their offices do not have 
information on the amount of bait sold or the acreage controlled. 
Applicators are required to keep records for 3 years; however, they are 
not required to submit these records to a central location (Roybal, 
U.S. Environmental Protection Agency, in litt. 2002). We received 
limited information regarding sales of toxicants from APHIS and from 
some State agencies. This information is provided below.
    APHIS provides technical assistance and conducts operational work 
in several States within the historic range of the black-tailed prairie 
dog. While APHIS is only one avenue available to landowners seeking 
chemical control and provides only a partial picture of control 
activities, some perspective regarding general trends can be gained 
from their records. For example, sales of zinc phosphide oats in 
Colorado, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, Texas, 
and Wyoming totaled 2,062 kilograms (4,545 pounds) in 1998, 3,445 
kilograms (7,595 pounds) in 1999, 3,647 kilograms (8,040 pounds) in 
2000, 3,223 kilograms (7,105 pounds) in 2001, and 5,933 kilograms 
(13,080 pounds) in 2002 (Green, APHIS, in litt. 2002). APHIS has no 
operational programs in Kansas or South Dakota.
    Statewide estimates of toxicant sales are available for Nebraska, 
South Dakota, and Wyoming. The South Dakota Department of Agriculture 
sold approximately 12,247 kilograms (27,000 pounds) of zinc phosphide 
oat bait to South Dakota and Nebraska in 2000, 19,505 kilograms (43,000 
pounds) in 2001, 44,452 kilograms (98,000 pounds) in 2002, and 61,235 
kilograms (135,000 pounds) in 2003 (Fridley, South Dakota Department of 
Agriculture, in litt. 2004). At least 7,343 kilograms (16,189 pounds) 
of zinc phosphide bait was purchased from South Dakota and applied in 
Nebraska in 2002 (Hobbs, APHIS, pers. comm. 2003). In addition to legal 
control, numerous anecdotal reports have been received regarding 
illegal control activities; however, no data are available to evaluate 
the scope of these activities (Fritz, NGPC, in litt. 2002). In Wyoming, 
sales of toxicants were reported as ``greatly increased between 2000 
and 2001, especially in counties such as Campbell, Weston, and 
Niobrara.'' Statewide sales of zinc phosphide increased from 3,643 to 
28,579 kilograms (8,031 to 63,007 pounds). Aluminum phosphide fumotoxin 
sales increased from 126 to 713 flasks over the same period. Sales 
trends for 2002 also appeared to be on the increase for most counties 
(Wichers, WGFD, in litt. 2002).
    Little information regarding the extent of chemical control is 
available for other States. In Texas, it was reported that in 2002, 
20,500 aluminum phosphide tablets and 295 kilograms (650 pounds) of 
zinc phosphide oat bait were used by APHIS to treat an estimated 1,000 
hectares (2,463 acres) (Leland, APHIS, in litt. 2002). APHIS was not 
the only source of toxicants in Texas (Young, TPWD, in litt. 2002). 
Green (APHIS, in litt. 2002) reported that in 2002, APHIS sold 127 
kilograms (280 pounds) of zinc phosphide in North Dakota, 331 kilograms 
(730 pounds) in New Mexico, and 590 kilograms (1,300 pounds) in 
Montana. APHIS was not the only source of zinc phosphide in these 
States. In Oklahoma, the ODWC has issued permits to control 
approximately 28 hectares (70 acres) (Duffy, ODWC, in litt. 2003). 
Rosmarino (Forest Guardians et al. in litt. 2003a) reported on numbers 
of prairie dogs poisoned in urban areas along the Front Range of 
Colorado in 2001 and 2002. If a density of 10 prairie dogs per acre is 
assumed for this report and a number of 500 individuals is assumed 
where a quantity of ``hundreds'' is given, approximately 570 hectares 
(1,400 acres) were poisoned in 2001 and 900 hectares (2,200 acres) in 
2002. Both of these estimates equate to less than 0.5 percent of the 
Statewide population of the species in Colorado at that time.
    When grain zinc phosphide bait is applied according to directions, 
it can result in an 80 to 90 percent reduction in prairie dog numbers. 
The recommended application rate is 0.15 kilogram/0.4 hectare (0.33 
pound/1 acre) (Hygnstrom et al. 1994). When applied properly, aluminum 
phosphide can provide greater than 90 percent control. Thus, some of 
the above numbers may indicate the potential for significant impacts to 
the species. For example, if all of the product were applied within the 
year of purchase at the recommended application rate, approximately 
164,000 hectares (405,000 acres) would have been treated in South 
Dakota and Nebraska in 2003. In Wyoming, approximately 76,486 hectares 
(189,000 acres) would have been treated in Wyoming in 2001 if all of 
the oat bait were applied within the year of purchase at the 
recommended application rate. It is unclear to what extent consumers 
are effectively applying the toxicant they have available.
    Furthermore, site-specific and range-wide data indicate the 
species' resiliency to the impacts of chemical control. In the Pine 
Ridge/Oglala Sioux Reservation example discussed above, estimates 
occupied habitat increased from approximately 8,000 to 12,000 hectares 
(20,000 to 30,000 acres) in 1999 to approximately 36,000 to 40,000 
hectares (89,000 to 100,000 acres) in 2003. Other site-specific 
examples of populations rebounding are discussed

[[Page 51226]]

in the distribution, abundance, and trends section of this document. 
Recent range-wide data also show little evidence of permanent impacts 
from chemical control. It is possible that population densities may 
have been reduced on some lands due to chemical control. Additionally, 
black-tailed prairie dogs may have been extirpated from some specific 
sites. Although we acknowledge extant and potentially significant local 
effects on some populations, based on the new information above and 
recent State-by-State range-wide estimates of occupied habitat, we now 
conclude that impacts on the black-tailed prairie dog due to chemical 
control are not a threat to the extent that the species could become 
endangered in the foreseeable future.
    We believe that synergistic effects likely impact the black-tailed 
prairie dog; however, we are unable to adequately describe and quantify 
these effects. Additionally, we are unaware of data from similar 
species in similar ecological circumstances that would infer that 
similar influences would cause the status of the black-tailed prairie 
dog to meet the Act's definition of a threatened species.

Revised Petition Finding

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
faced by this species. We reviewed the petition, information available 
in our files, other published and unpublished information, and 
information submitted to us following our 90-day petition finding (64 
FR 14425, March 25, 1999)), the original 12-month finding (65 FR 5476, 
February 4, 2000), and the 2001 and 2002 candidate assessments and 
resubmitted petition findings (66 FR 54808, October 30, 2001, and 67 FR 
40657, June 13, 2002, respectively). On the basis of the best 
scientific and commercial information available, we find that the 
petitioned action to list the black-tailed prairie dog under the 
provisions of the Endangered Species Act is not warranted.
    State agencies now estimate approximately 745,400 hectares 
(1,842,000 acres) of occupied habitat across 10 western States. This 
estimate of the occupied habitat of black-tailed prairie dog has played 
a substantial role in this decision. Previously, we focused attention 
on a few large black-tailed prairie dog populations impacted by plague 
and extrapolated population losses at these sites across the species' 
entire range. Based on the updated distribution, abundance, and trends 
data, it appears that these extrapolations were not correct. Dramatic 
fluctuations in the amount of black-tailed prairie dog occupied habitat 
at specific large complexes may occur due to plague epizootics or 
chemical control, but they do not appear to influence range-wide 
species persistence.
    The magnitude and immediacy of the threat should be viewed pursuant 
to the definitions of the Act. To be considered a threat, a factor 
should be shown to play a significant role in the population dynamics 
of the species such that it is likely to become an endangered species 
within the foreseeable future throughout all or a significant portion 
of the range. None of the five listing factors as described in section 
4(a) of the Act and further described at 50 CFR 424.11 rise to this 
level of threat. Thus, the species does not meet the Act's definition 
of a threatened species. As a result we find that the species is not in 
danger of extinction in the foreseeable future and, therefore, the 
petitioned action is not warranted. Thus we also no longer consider the 
species to be a candidate for listing.
    We will continue to monitor the status of the species, and to 
accept additional information and comments from all concerned 
governmental agencies, the scientific community, industry, or any other 
interested party concerning this finding. We will reconsider this 
determination in the event that new information indicates that the 
threats to the species are of a considerably greater magnitude or 
imminence than identified here.

References

    A complete list of all references cited herein is available upon 
request from the South Dakota Fish and Wildlife Office, U.S. Fish and 
Wildlife Service (see ADDRESSES).

Author

    The primary author of this finding is the South Dakota Fish and 
Wildlife Office, U.S. Fish and Wildlife Service staff (see ADDRESSES).

Authority

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

    Dated: August 12, 2004.
Marshall P. Jones, Jr.,
Acting Director, Fish and Wildlife Service.
[FR Doc. 04-18872 Filed 8-17-04; 8:45 am]
BILLING CODE 4310-55-P