[Federal Register: March 25, 1999 (Volume 64, Number 57)]
[Proposed Rules]               
[Page 14424-14428]
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 for 
a Petition To List the Black-Tailed Prairie Dog as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.


SUMMARY: We have received a petition to list the black-tailed prairie 
dog (Cynomys ludovicianus) throughout its range in Arizona, Colorado, 
Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South 
Dakota, Texas, Wyoming, southern Saskatchewan, Canada, and northern 
Mexico. The petition presents substantial scientific and commercial 
information that the request for listing may be warranted. Therefore, 
we are initiating a status review to determine if the petitioned action 
is warranted. To ensure that the review is comprehensive, we are 
soliciting information and data regarding this action. We will use 
information received during the comment period for this status review 
in our review of the black-tailed prairie dog.

DATES: The finding announced in this document was made on March 17, 
1999. A status review is initiated. To have

[[Page 14425]]

information considered in the status review and subsequent 12-month 
finding for the petition, submit information to us by May 24, 1999.

ADDRESSES: Data, information, technical critiques, comments, or 
questions relevant to this finding should be submitted to the Field 
Supervisor, Ecological Services, U.S. Fish and Wildlife Service, 420 
South Garfield Avenue, Suite 400, Pierre, South Dakota 57501-5408. You 
may inspect the petition, finding, and supporting documents, by 
appointment, at the above address. You may request and receive 
electronic copies of the petition and finding via e-mail from 

FOR FURTHER INFORMATION CONTACT: Pete Gober, at the address given 
above, or telephone (605) 224-8693.



    Section 4(b)(3)(A) of the Endangered Species Act (Act) of 1973 as 
amended (16 U.S.C. 1531 et seq.), requires us to make a finding on 
whether a petition to list, delist, or reclassify a species presents 
substantial scientific and commercial information to demonstrate that 
the petitioned action may be warranted. This finding is to be based on 
all information available to us at the time we make the finding. To the 
maximum extent practicable, we make this finding within 90 days of 
receipt of the petition and we promptly publish a Notice in the Federal 
Register. This document provides a summary of the information in the 
90-day finding, which is our decision document. When we make a positive 
finding, we are required to promptly initiate a status review of the 
species. A positive 90-day finding is not a decision to list a species. 
This document meets the requirement for publication of a 90-day finding 
on the petition discussed below.
    We have made a 90-day finding on a petition to list the black-
tailed prairie dog (Cynomys ludovicianus). The petition, dated July 30, 
1998, was submitted by Thomas France, Esq., and Dr. Sterling Miller, 
both of Missoula, Montana, and Kimberly Graber, Esq., of Denver, 
Colorado, on behalf of the National Wildlife Federation (NWF; ``the 
Petitioners''), and was received by us on July 31, 1998, accompanied by 
a letter from Mark Van Putten, Chief Executive Officer for NWF. The 
Petitioners requested that we list the black-tailed prairie dog as a 
threatened species throughout its range. The Petitioners also requested 
that the black-tailed prairie dog receive emergency listing under the 
    We received another petition regarding the same species from the 
Biodiversity Legal Foundation, the Predator Project, and Jon C. Sharps 
on August 26, 1998. They requested that we list the black-tailed 
prairie dog as threatened throughout its known historic range in the 
contiguous United States. We accepted this second request as 
supplemental information to the NWF petition.
    The Petitioners presented extensive information regarding the 
biology and ecology of the black-tailed prairie dog. The Petitioners 
and other interested parties also provided supplemental information to 
the NWF petition that has been considered in this finding. 
Additionally, we have reviewed information in our files, other readily 
available information, and information submitted by Federal, State, and 
Tribal agencies. We expect to solicit and receive additional 
information through the status review of the species.
    The Petitioners expressed concern about continuing human activities 
that pose a threat to the black-tailed prairie dog and additional 
threats that might be anticipated following the filing of their 
petition. The Petitioners predicted that poisoning and shooting 
activities would increase and result in significant population declines 
for the species during the normal rulemaking process. Thus, the 
petitioners requested that we emergency list the black-tailed prairie 
dog. Under 16 U.S.C. 1533(b)(7), the Secretary of the Interior has the 
authority to suspend normal rulemaking procedures and issue emergency 
regulations for a species, when there is a significant risk to the 
species and where the routine listing process is not adequate to 
prevent losses that may result in extinction. We determined, and 
advised the Petitioners, that based on our initial review of the 
petition, it would be inappropriate to emergency list this species 
based on its current known status. Furthermore, it is typically 
inappropriate to emergency list a species as threatened because the 
threatened definition only covers species that are at risk of becoming 
endangered, not extinct. We acknowledged that existing regulatory 
mechanisms for black-tailed prairie dogs may not preclude continued 
losses of individuals from some populations of the species. However, we 
believe that the normal petition review and rulemaking procedures are 
sufficient and appropriate. We will revisit the issue of emergency 
listing if the immediacy or magnitude of threats increase such that 
black-tailed prairie dogs require immediate protection.
    The historical range of the black-tailed prairie dog includes 
southern Saskatchewan, Canada; eastern Montana, Wyoming, Colorado, and 
New Mexico; western North Dakota; western and central South Dakota, 
Nebraska, Kansas, and Oklahoma; western, northwestern, and northern 
Texas; and northeastern Mexico (Miller et al. 1996). The species was 
present historically in eastern Arizona, but was extirpated in recent 
years (Alexander 1932). The Petitioners noted that the species still 
occurs generally throughout its historic range, although much reduced 
in numbers and in the amount of habitat that it occupies. The 
Petitioners asserted that the black-tailed prairie dog once occupied 
more than 100 million acres (ac) or 40 million hectares (ha) of western 
North America, contrasted that with current estimates of occupied 
habitat (Knowles 1998a), and concluded that the species' population has 
been reduced by 99 percent. The Petitioners attributed reductions in 
occupied habitat to habitat loss and degradation related to the 
conversion of prairie grasslands to farmland, urban development, 
extensive poisoning efforts, unregulated shooting, disease, 
combinations of these factors, and other causes.
    The Petitioners asserted that the small size and widely spaced 
distribution of most remaining black-tailed prairie dog colonies create 
concerns of adverse influences of habitat fragmentation, dispersal 
limitations, and other factors. They asserted that the cumulative 
effect of these factors is to reduce the viability of the species and 
increase the probability of extinction for the species. They 
acknowledged that the number of individual black-tailed prairie dogs 
appears to be comparable to many other species that are not thought to 
be in danger of extinction. However, they argued that the species is 
threatened as evidenced by (and due to) its precipitous historic 
population decline, its recent population declines, and the number and 
variety of threats to it. The Petitioners emphasized the colonial 
nature of the black-tailed prairie dog and the subsequent population 
responses en masse to habitat conversion, poisoning efforts, and 
especially disease (i.e., sylvatic plague, a disease exotic to North 
America and to which prairie dogs have no immunity).
    The Petitioners pointed out that all States within the range of the 
black-tailed prairie dog have classified it as a pest for agricultural 
purposes, either permitting or requiring eradication of the species. 
They also asserted that these States allow or promote unlimited

[[Page 14426]]

recreational shooting. The Petitioners believed that there are 
inconsistent Federal policies regarding all species of prairie dogs, 
and that the legal mechanisms under which they have declined remain in 
place. The Petitioners asserted that some Tribes have a sophisticated 
management program for the black-tailed prairie dog and play an 
important role in its conservation.
    We have previously addressed the status of the black-tailed prairie 
dog. On October 21, 1994, the Biodiversity Legal Foundation and Jon C. 
Sharps petitioned us to classify the black-tailed prairie dog as a 
Category 2 candidate species pursuant to the Administrative Procedures 
Act and the ``intent of the Endangered Species Act'' (Biodiversity 
Legal Foundation and Sharps 1994). At that time a Category 2 candidate 
species was a taxon for which we believed listing might be appropriate, 
but for which there was not sufficient data regarding biological 
vulnerability or threats to support a proposed rule. We no longer use 
this candidate classification system. The addition of a species to the 
list of Category 2 candidates was not an action petitionable under the 
Act. However, we reviewed the status of the black-tailed prairie dog in 
1994-1995 and concluded that the numbers, distribution, and 
reproductive capability of the species were such that it did not 
warrant candidate status at that time (Terrell, U.S. Fish and Wildlife 
Service, in litt. 1995). New information has become available since 
then and we believe that an additional status review is now 
    Black-tailed prairie dogs are small, stout, ground squirrels 
approximately 14-17 inches (in) long and weighing 1-3 pounds (lbs). 
Black-tailed prairie dogs are highly social colonial, diurnal, 
burrowing animals. Individual appearance within the species varies with 
a mix of brown, black, gray, and white, but with a characteristic 
black-tipped tail (Hoogland 1995). The black-tailed prairie dog is a 
colonial ground squirrel and one of five species in the genus Cynomys, 
all of which occur in western North America. There are two subspecies 
of the black-tailed prairie dog--the Arizona black-tailed prairie dog 
(C. l. arizonensis), and the more widespread black-tailed prairie dog 
(C. l. ludovicianus) (Hall and Kelson 1959), which is usually what is 
thought of when the common name ``black-tailed prairie dog'' is used.

Historical and Current Distribution

    The Arizona subspecies (C. l. arizonensis) is found in northeastern 
Mexico (Ceballos et al. 1993), is extirpated (extinct) in Arizona 
(Alexander 1932), may or may not be present in New Mexico, and is 
remnant in west Texas (Davis 1974; Hall and Kelson 1959). Individuals 
of this subspecies in Chihuahua, Mexico, comprise the largest prairie 
dog complex (90,000 ac or 36,000 ha) remaining in North America. This 
complex is the only significant population remaining in Mexico 
(Ceballos et al. 1993). The black-tailed prairie dog is listed as 
threatened by the Lista de las Especies Amerzadas, the official 
threatened and endangered species list of the Mexican Government 
(SEMARNAP 1994).
    The major subspecies, C. l. ludovicianus, is found in Montana, 
Wyoming, Colorado, New Mexico, North Dakota, South Dakota, Nebraska, 
Kansas, Oklahoma, northern Texas, and Canada. In Canada, the black-
tailed prairie dog is designated as vulnerable by the Committee on the 
Status of Endangered Wildlife in Canada. In the remainder of this 
finding, the name ``black-tailed prairie dog'' will be used to include 
both subspecies.
    In addition to the large colony in Mexico, we know of only six 
other black-tailed prairie dog colonies larger than 10,000 ac (4,000 
ha) remaining throughout the species' range--one in Montana, one in 
Wyoming, and four in South Dakota. South Dakota, the only State where 
plague is absent, contains an estimated 32 percent of the remaining 
black-tailed prairie dog occupied habitat. All other remaining black-
tailed prairie dog colonies are smaller, more isolated, and spottily 
distributed throughout the species range.
    Rangewide, the black-tailed prairie dog is estimated to inhabit 
only a small fraction of the area that it once occupied, perhaps as 
little as 800,000 ac (320,000 ha) (Knowles 1998a) of what may have been 
300 million ac or more (120 million ha) in its original range (Seton 
1953). Seton (1953) estimated that individuals of black-tailed prairie 
dogs once numbered 5 billion. Many prairie dog colonies were quite 
large and interconnected (Miller et al. 1996). By 1961, the area 
occupied by black-tailed prairie dogs in the United States had declined 
to approximately 364,000 ac (147,000 ha) (Bureau of Sport Fisheries and 
Wildlife 1961). Knowles (1998a), Weurthner (1997), Barko (1997), 
Knowles (1995), Mulhern and Knowles (1995), and Fagerstone and Ramey 
(1995) concluded that an approximate decrease in area occupied of 94-99 
percent had occurred compared to historic estimates. Generally, State 
wildlife agencies confirm this decline, but some point out that 
disproportionately more occupied habitat remains in some areas than in 
others. Knowles' (1998a) estimated that 677,000 ac (274,000 ha) of 
black-tailed prairie dog occupied habitat in the United States remains. 
Some increases in black-tailed prairie dog occupied habitat occurred in 
1961-1980 (notably in Wyoming and South Dakota), but in 1980-1998, 
significant declines occurred in Montana, Mexico, and South Dakota.
    Three major impacts have had substantial influence on black-tailed 
prairie dog populations and distribution. The petitioners asserted that 
the first major impact on the species historically was the conversion 
of prairie grasslands to farmland in the eastern portion of its range, 
and that the second major impact on the species was large-scale 
poisoning conducted to reduce perceived competition between prairie 
dogs and domestic livestock. A third major impact on the species was 
the inadvertent introduction of an exotic disease from the Old World, 
sylvatic plague, into the North American prairie ecosystem. Other 
authors also address these threats to the black-tailed prairie dog, as 
discussed below.


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

    The petitioners asserted that conversion of prairie habitat to 
farmland was one of the primary causes of the decline in occupied 
habitat of the black-tailed prairie dog. Between 1880 and 1899, 104 
million ac (42 million ha) of the total western plains surface area was 
converted to crop productions (Laycock 1987). Native grasslands have 
been reduced by approximately 60 percent (Burke in prep.) resulting in 
significant destruction of black-tailed prairie dog habitat. Some 
agricultural conversion of native grasslands continues today, and could 
accelerate with the increase of dryland cropping and use of genetically 
engineered drought resistant crop strains. Hexem and Krupa (1987) 
identified 57,700,000 ac (23,400,000 ha) of unplowed land in the 
western Great Plains with potential for cropland conversion. Such 
conversion could significantly reduce the remaining native prairie and 
black-tailed prairie dog habitat.
    Urbanization also presents a significant loss of black-tailed 
prairie dog habitat in local areas near metropolitan areas such as 

[[Page 14427]]

Kansas; Helena, Montana (Knowles 1995); and the Front Range of Colorado 
near Denver (Weber, Colorado Division of Wildlife, pers. comm. 1998). 
Habitat loss also occurs through degradation of burrows and vegetation 
changes in areas where black-tailed prairie dogs have been removed. 
Once underground burrows collapse or there is an increase in woody or 
taller vegetation, the species is less likely to reestablish itself in 
the area. At the Rocky Mountain Arsenal National Wildlife Refuge in 
Colorado, reintroduced black-tailed prairie dogs reestablished 
themselves quickly where intact burrows constructed by previous prairie 
dogs (extirpated by sylvatic plague) had not deteriorated (Seery, U.S. 
Fish and Wildlife Service, pers. comm. 1998). Where burrows had 
deteriorated, prairie dogs established themselves slowly and with 
little success. Weltzin et al. (1997) determined that historically, 
black-tailed prairie dogs, and the herbivores and granivores associated 
with their colonies, probably maintained grassland and savanna by 
preventing woody species such as mesquite from establishing or 
attaining dominance. List (1997) reported that poisoning of black-
tailed prairie dogs in Mexico resulted in the invasion of mesquite 
shrubs that rendered the landscape unsuitable for reoccupation by the 
species; moreover, fire suppression would likely maintain this 
situation. Davis (1974) also noted that removal of the species from 
some sites in Texas resulted in the invasion of brush. Thus, when 
degradation of burrows or vegetation changes occur, the amount of 
habitat suitable for recolonization may be reduced. Current levels of 
conversion of rangeland to farmland or urban development may not be as 
important to the species' numbers and viability as are indirect losses 
caused by poisoning or disease. These indirect losses of individuals or 
local populations may result in habitat loss for the species through 
the deterioration of burrows and the alteration of vegetative 

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

    One activity impacting black-tailed prairie dog populations in some 
local areas is unregulated recreational (sport or varmint) shooting. 
Shooting has increased appreciably in popularity in recent years. An 
example of this is the Buffalo Gap National Grasslands in South Dakota 
where the number of annual shooter days has increased from a few 
hundred in the mid-1990's to an estimated 6,500 in 1998 (Perry, U.S. 
Forest Service, pers. comm., 1998). High-powered rifles with high-
quality scopes enable the modern varmint shooter to be consistently 
accurate at distances of 400 yards (yd) (400 meters (m)) or greater, 
and an individual shooter may shoot a considerable number of animals 
each day (Kayser 1998). Many States do not require hunting licenses and 
have no bag limits or seasonal restrictions for taking prairie dogs. 
Prairie dog density may decrease with increased shooting pressure and 
prairie dogs may spend more time on alert and less time foraging 
(Vosberg 1996). Shooting also may contribute to population reduction 
and fragmentation, reduce colony productivity and health, and preclude 
or delay recovery of colonies reduced by other factors such as sylvatic 
plague. Recreational shooting may significantly impact colonies in 
local areas where shooting is most intense or colony numbers are 

already reduced from other losses.

C. Disease or Predation

    Sylvatic plague is a non-native disease caused by the bacterium, 
Yersinia pestis, which fleas can harbor and transmit to rodents and 
other species (Cully 1989). The term ``sylvatic'' refers to the 
occurrence of the disease in the wild (Berkow 1982). Barnes (1993) 
recorded sylvatic plague in 76 species of 6 mammalian orders, although 
it is primarily a rodent disease. Rodent species vary in their 
susceptibility to plague, with some species acting as hosts or carriers 
of the disease or infected fleas and showing no symptoms (e.g., 
kangaroo rats, Dipodomys sp., and deer mice, Peromyscus maniculatus). 
Conversely, black-tailed and Gunnison's prairie dogs show nearly 100 
percent mortality when exposed to sylvatic plague (Barnes 1993, Cully 
    Sylvatic plague is an exotic disease foreign to the evolutionary 
history of North American species. Scientists discovered the plague 
among wild rodents near San Francisco in 1908 and it has spread 
throughout much of the Great Plains over the past century (Eskey and 
Haas 1940, Miles et al. 1952 in Cully 1989, Ecke and Johnson 1952). 
Black-tailed prairie dogs show neither effective antibodies nor 
immunity to the disease. Death occurs quickly for prairie dogs exposed 
to sylvatic plague; noticeable symptoms usually do not develop (Cully 
1993). Data obtained from the Rocky Mountain Arsenal National Wildlife 
Refuge show that plague has the potential to severely depress black-
tailed prairie dog populations and cause local extirpations (Seery and 
Matiatos, in press; U.S. Fish and Wildlife Service 1998). Scientists 
have also observed longterm plague-related declines in white-tailed 
prairie dogs near Meeteetse, Wyoming (Biggins, U.S. Geological Survey, 
Biological Resources Division, pers. comm. 1998).
    Many mammals, snakes, and raptors prey on prairie dogs (Hoogland 
1995) and the species has evolved resilience to natural levels of 
predation. Scientists do not generally see predation as a threat to the 
species but, in unusual circumstances intense levels of predation may 
be problematic to individual small colonies, particularly if they are 
already reduced by other causes.

D. The Inadequacy of Existing Regulatory Mechanisms

    All States within the historic range of the black-tailed prairie 
dog classify the species as a pest for agricultural purposes and either 
permit or require their eradication (Mulhern and Knowles 1995). Fish 
and wildlife agencies in many States classify black-tailed prairie dogs 
by categories such as ``unclassified game'' that permit licensed or 
unlicensed shooting with no limitations on take or season. Knowles 
(1995) reviewed Federal regulatory management policies as they relate 
to the black-tailed prairie dog. Significant black-tailed prairie dog 
occupied habitat is found on public lands managed by the BIA, the 
Bureau of Land Management (BLM), the Service, USFS, and the National 
Park Service (NPS). The BLM manages prairie dogs to meet multiple-use 
resource objectives (Knowles 1995). Various National Forest Resource 
Management Plans address black-tailed prairie dog habitat on USFS-
administered land; these plans reflect Forest Service policy, not 
regulation. Two tribes have voluntary prairie dog management plans in 
place (Knowles 1995). In areas where black-footed ferrets are re-
established, some programs to conserve prairie dogs are in place.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Control (Poisoning)
    Hanson (1993) cited poisoning as a major factor in the reduction of 
prairie dog populations. An extensive poisoning effort has occurred 
over most of the species' range (Bell 1921, Cain et al. 1971, Anderson 
et al. 1986, Roemer and Forrest 1996, and Forrest and Proctor in 
prep.). Organized prairie dog control gained momentum from 1916 to 
1920, when property owners and Federal agencies poisoned prairie dogs

[[Page 14428]]

on millions of acres of western rangeland (Bell 1921); Federal programs 
were responsible for much of this effort. From 1937-1968, 30,447,355 ac 
(12,321,875 ha) of occupied prairie dog habitat was controlled (Cain et 
al. 1971). After the 1970's some toxicants previously used for prairie 
dog control were banned and although prairie dog control continued, it 
occurred at a reduced rate.
    Federal agencies are involved to varying degrees in active control 
of prairie dog colonies. The Environmental Protection Agency regulates 
use of prairie dog poisons. The Animal and Plant Health Inspection 
Service-Wildlife Services (APHIS-WS) provides technical assistance and 
distributes prairie dog poison to State and Federal agencies, Tribes, 
and private landowners. Based on information obtained from the APHIS 
Freedom of Information Act web page (foia.aphis.usda.gov), the agency 
controlled 95,076 ac (38,480 ha) of black-tailed prairie dog habitat 
from 1991-1996. Although this number could have included some acreage 
that was treated more than once, this number indicates that over a 5-
year period, AHPIS-WS alone has conducted prairie dog control on 14 
percent of the estimated remaining black-tailed prairie dog habitat.
    Control programs have significantly reduced black-tailed prairie 
dog populations. These programs essentially remove all animals from the 
area treated and directly contribute to habitat fragmentation and 
vegetation changes that limit future recolonization by the black-tailed 
prairie dog. In particular, Federal control programs may play a 
significant role in the continued decline of black-tailed prairie dog 

Habitat Fragmentation

    The grassland biome in North America has arguably suffered the most 
extensive fragmentation and transformation of any biome on the 
continent (Groombridge 1992). More fragmented, more isolated, and less 
connected populations usually have higher extinction rates (MacArther 
and Wilson 1967, Wilcox and Murphy 1985, Clark 1989). Miller et al. 
(1996) describe existing prairie dog populations as small, disjunct, 
and geographically isolated. They further describe the discontinuous 
nature of remaining populations as widely separated islands where 
habitat fragmentation has increased the likelihood of individual colony 
extinction due to genetic inbreeding and random demographic events. 
Lost genetic diversity is inherently detrimental to most species. 
Black-tailed prairie dog dispersal movements that previously offset 
these adverse effects likely are limited by short migration distances, 
as reported by Hoogland (1995) and Knowles (1985), and longer distances 
between remaining colonies.


    We have reviewed the petition, as well as other available 
information, published and unpublished studies and reports, information 
received from State, Tribal and private entities, and agency files. On 
the basis of our review of the petition, literature cited in the 
petition, and other readily available information, we find there is 
sufficient information to indicate that listing of the black-tailed 
prairie dog may be warranted, and we initiate a status review. However, 
we also find there is no substantial information to warrant an 
emergency listing at this time, as was requested by the petitioner.
    Based on our review of the petition and other readily available 
information, we believe that the decline, especially the recent 
decline, of the black-tailed prairie dog likely is due to many factors. 
One of the most influential and unpredictable factors is the widespread 
occurrence of plague, an exotic and completely lethal disease to the 
species. We believe that we should evaluate black-tailed prairie dog 
reduced colony size and connectivity in light of factors such as 
plague, control, land conversion, and shooting, in a thorough analysis 
of the status of the species. Therefore, with the completion of this 
90-day Finding, a status review of the species will be undertaken with 
a subsequent Finding as to whether the petitioned action is warranted 
(section 4(b)(3)(B) of the Act). We will consider all relevant 
information in conducting a full status review to determine if listing 
is warranted. We are hereby requesting any additional data or 
scientific information from the public, scientific community, Tribal, 
State and Federal governments, and other interested parties concerning 
the status of and threats to the black-tailed prairie dog throughout 
the species' range.

References Cited

    You may request a complete list of all references cited herein, as 
well as others, from the Service's Pierre Field Office (see ADDRESSES 


    Pete Gober (see ADDRESSES section) prepared this document.


    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531-1544 et seq.).

    Dated: March 17, 1999.
Jamie Rappaport Clark,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 99-7273 Filed 3-23-99; 8:45 am]