Endangered and Threatened Wildlife and Plants: 90-Day Finding on a Petition To List the Wild Plains Bison or Each of Four Distinct Population Segments as Threatened, 10299-10310 [2011-4121]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 37 (Thursday, February 24, 2011)]
[Proposed Rules]
[Pages 10299-10310]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-4121]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2010-0095; MO 92210-0-0008-B2]


Endangered and Threatened Wildlife and Plants: 90-Day Finding on 
a Petition To List the Wild Plains Bison or Each of Four Distinct 
Population Segments as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service, announce a 90-day 
finding on a petition to list the wild plains bison (Bison bison 
bison), or each of four distinct population segments (DPSs), as 
threatened under the Endangered Species Act of 1973, as amended (Act). 
Based on our review, we find that the petition does not present 
substantial information indicating that listing may be warranted. 
Therefore, we are not initiating a status review in response to this 
petition. However, we ask the public to submit to us any new 
information that becomes available concerning the status of, or threats 
to, the wild plains bison or its habitat at any time.

DATES: The finding announced in this document was made on February 24, 
2011.

ADDRESSES: This finding is available on the Internet at https://www.regulations.gov at Docket No. FWS-R6-ES-2010-0095. Supporting 
documentation we used in preparing this finding is available for public 
inspection, by appointment, during normal business hours at the U.S. 
Fish and Wildlife Service, Ecological Services, Wyoming Field Office, 
5353 Yellowstone Road, Suite 308A, Cheyenne, WY 82009. Please submit 
any new information, materials, comments, or questions concerning this 
finding to the above address.

FOR FURTHER INFORMATION CONTACT: Mark Sattelberg, Field Supervisor, 
Wyoming Field Office (see ADDRESSES), by telephone (307-772-2374) or by 
facsimile (307-772-2358). If you use a telecommunications device for 
the deaf (TDD), please call the Federal Information Relay Service 
(FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(A) of the Act (16 U.S.C. 1531 et seq.) requires 
that we make a finding on whether a petition to list, delist, or 
reclassify a species presents substantial scientific or commercial 
information indicating that the petitioned action may be warranted. We 
are to base this finding on information provided in the petition, 
supporting information submitted with the petition, and information 
otherwise available in our files. To the maximum extent practicable, we 
are to make this finding within 90 days of our receipt of the petition, 
and publish our notice of the finding promptly in the Federal Register.

[[Page 10300]]

    Our standard for substantial scientific or commercial information 
within the Code of Federal Regulations (CFR) with regard to a 90-day 
petition finding is ``that amount of information that would lead a 
reasonable person to believe that the measure proposed in the petition 
may be warranted'' (50 CFR 424.14(b)). If we find that substantial 
scientific or commercial information was presented, we are required to 
promptly conduct a species status review, which we subsequently 
summarize in our 12-month finding.

Petition History

    On June 22, 2009, we received a petition, dated June 19, 2009, from 
James A. Bailey and Natalie A. Bailey, requesting that the wild plains 
bison be listed as threatened or that each of its four major ecotypes 
be considered DPSs and listed as threatened (Bailey and Bailey 2009, 
cover page). The petition clearly identified itself as such and 
included the requisite identification information for the petitioners, 
as required by 50 CFR 424.14(a). In a July 14, 2009, letter to the 
petitioners, we responded that we reviewed the information presented in 
the petition and determined that issuing an emergency regulation 
temporarily listing the subspecies under section 4(b)(7) of the Act was 
not warranted. We also stated that due to staff and budget limitations, 
we would not be able to begin work on a 90-day finding for this 
petition until Fiscal Year 2010 or 2011. On August 25, 2010, we 
received a letter from the petitioners requesting that we consider (1) 
New information regarding genetic diversity; (2) a publication by Gates 
et al., 2010; (3) the National Park Service's (NPS) draft environmental 
impact statement on a proposed brucellosis remote vaccination program; 
and (4) any new information that was added to our files since the date 
of the original petition. This finding addresses the petition and all 
information readily available to us at this time.

Previous Federal Action(s)

    We received a petition to list the bison herd at Yellowstone 
National Park (Yellowstone) in the northwest corner of Wyoming as a 
subspecies or ``distinct population group'' on February 11, 1999. We 
completed a 90-day finding on August 15, 2007 (72 FR 45717). Based upon 
the information available at that time, we determined that there was 
substantial information indicating that the Yellowstone bison herd may 
meet the criteria of discreteness and significance as defined by our 
policy on DPSs. However, we also determined that there was not 
substantial information indicating that listing the Yellowstone bison 
herd was warranted throughout all or a significant part of its range, 
and a status review was not conducted.

Species Information

Taxonomy
    Bison occupied Eurasia about 700,000 years ago and moved across the 
Bering Land Bridge into Alaska during the middle Pleistocene Epoch 
300,000 to 130,000 years ago (Martin 1970, p. 220; Kurt[eacute]n and 
Anderson 1980, p. 39; Gates et al. 2010, p. 5). Bison moved further 
south into the grasslands of central North America as ice sheets 
retreated 130,000 to 75,000 years ago (Gates et al. 2010, p. 5). The 
genus Bison is represented by two extant species, the American bison 
(Bison bison) and the European bison (B. bonasus) (Halbert 2003, p. 1; 
Gates et al. 2010, p. 15).
    Linnaeus first classified the bison in 1758, assigning the animal 
to Bos, the same genus as domestic cattle (Bos taurus) (Gates et al. 
2010, p. 13). During the 19th century, taxonomists determined that 
there was adequate anatomical distinctiveness to warrant assigning the 
bison to its own genus, Bison (Gates et al. 2010, p. 13). Since then, 
taxonomists have debated the validity of the genus. Some recommend 
returning the species to the genus Bos (Boyd 2003, p. 27; Halbert 2003, 
p. 2). However, most sources, including the American Society of 
Mammalogists, the Integrated Taxonomic Information System (ITIS), and 
the International Union for Conservation of Nature (IUCN), consider 
Bison as a separate genus from Bos (Meagher 1986, p. 1; Wilson and Ruff 
1999, pp. 342-343; Reynolds et al. 2003, p. 1010; Gates et al. 2010, p. 
15; ITIS 2010, p. 1). At this time, we support continued placement of 
bison in the genus Bison because the majority of taxonomic experts 
consider this classification to be correct.
    American bison is divided into two subspecies, first recognized by 
Rhoads in 1897 (Gates et al. 2010, p. 15). The two subspecies of 
American bison, plains bison (B. b. bison) and wood bison (B. b. 
athabascae), diverged approximately 5,000 years ago (Halbert 2003, p. 
1). Many authors have acknowledged subspecific status, although some 
attribute differences in morphology to environmental influences and not 
to genetics (Reynolds et al. 2003, p. 1009). Differences in physical 
traits between the two subspecies are not affected by geographic 
location, suggesting that differences are genetically controlled (Boyd 
2003, p. 32; Reynolds et al. 2003, p. 1009; Gates et al. 2010, pp. 15-
18). However, due to the recent divergence of the two bison subspecies, 
current genetic analysis techniques may not yet be able to detect the 
differences (Boyd 2003, p. 33). At this time, we support continued 
recognition of two subspecies of American bison because of geographic 
separation, morphological differences, and greater genetic differences 
between the two subspecies than within either of the two subspecies 
(Gates et al. 2010, pp. 15-18).
    Although the two entities are the same species (Bison bison bison), 
the petitioners generally limit their discussion to ``wild'' plains 
bison and assert that plains bison in commercial herds do not 
contribute to restoration of wild plains bison (Bailey and Bailey 2009, 
p. 5). Commercial herds are typically managed by private entities for 
production of meat and other commodities. Wild plains bison currently 
exist only in conservation herds, which are typically managed by 
governments and environmental organizations for the purpose of 
conserving the subspecies as wildlife in their native ecosystem. The 
petitioners contend that commercial herds are selectively bred, mixed 
with cattle genes, removed from natural selection, and not legally 
classified as wildlife under State laws (Bailey and Bailey 2009, p. 5). 
Further, the petitioners claim that wild plains bison in many 
conservation herds also may undergo selective culling, contain cattle 
genes from early efforts to crossbreed with domestic cattle, are 
removed from some aspects of natural selection, and in some cases are 
not legally classified as wildlife. These considerations are discussed 
in more detail under Factors B, D, and E.
Determination of the Listable Entity
    Neither the Act nor our implementing regulations expressly address 
whether commercial populations should be considered part of an entity 
being evaluated for listing, and no Service policy addresses the issue. 
Consequently, in our determination of how to address commercial 
populations in our analysis, we considered the following: (1) Our 
interpretation of the intent of the Act with respect to the disposition 
of native populations, and (2) criteria from another organization 
(IUCN) regarding the consideration of commercial populations in species 
evaluations.
Intent of the Endangered Species Act
    Section 2(b) of the Act states that the purposes of the Act ``are 
to provide a means whereby the ecosystems upon which endangered species 
and

[[Page 10301]]

threatened species depend may be conserved, to provide a program for 
the conservation of such endangered species and threatened species, and 
to take such steps as may be appropriate to achieve the purposes of the 
treaties and conventions set forth.'' In recent decisions, including a 
12-month finding published on September 8, 2010 (75 FR 54707), for the 
Arctic grayling (Thymallus arcticus) and a 12-month finding published 
on September 22, 2010, for the plant Agave eggersiana (75 FR 57720), we 
have focused on wild populations in our analysis of the species' status 
and potential threats because these are the populations that contribute 
to conservation of the species. Therefore, we believe that considering 
populations that contribute to species conservation in a listing 
evaluation is consistent with the intent of the Act.
Guidelines Used in Other Evaluation Systems
    The IUCN follows similar criteria in their species evaluations. The 
IUCN uses its Red List system to evaluate the conservation status and 
relative risk of extinction for species, and to catalogue and highlight 
plant and animal species that are facing a higher risk of global 
extinction (https://www.iucnredlist.org). The IUCN does not use the term 
``listable entity'' as the Service does; however, IUCN does clarify 
that their conservation ranking criteria apply to any taxonomic group 
at the species level or below (IUCN 2001, p. 4). Further, the IUCN 
guidelines for species status and scope of the categorization process 
focus on wild populations inside their natural range (IUCN 2001, p. 4; 
2003, p. 10) or so-called ``benign'' or ``conservation introductions,'' 
which are defined as attempts to establish a species, for the purpose 
of conservation, outside its recorded distribution, when suitable 
habitat is lacking within the historical range (IUCN 1998, p. 6; 2003, 
pp. 6, 10). Commercial plains bison herds are not eligible for 
consideration in the guidelines for evaluating conservation status 
under the IUCN (IUCN 2008, https://www.iucnredlist.org). In effect, the 
IUCN delineates between commercial plains bison herds and wild plains 
bison in conservation herds, in that commercial herds do not qualify 
for evaluation under the IUCN Red List system.
    There does not appear to be any conservation value for plains bison 
in commercial herds, as they are not used in restoration programs. 
Instead, their primary purpose is the production of meat and other 
commodities for commercial purposes. Our interpretation is that the Act 
intended to conserve species in their native ecosystems. We are not 
considering plains bison managed for production of meat and other 
commodities in this finding because we do not believe that individuals 
propagated and managed for commercial uses aid in the conservation or 
the recovery of the subspecies in the wild. For the purposes of this 
finding, we are analyzing status and potential threats to a petitioned 
entity that includes plains bison managed primarily for purposes of 
wildlife and ecosystem conservation, hereby referred to as wild plains 
bison, even though no bison herd has remained in a completely wild 
state since prehistoric times (see our discussion on Significance, 
below). Consequently, we do not address commercial bison herds further 
in this finding.
    In summary, we accept the characterization of plains bison as a 
valid subspecies because the preponderance of currently available 
information indicates that the genus, species, and subspecies 
nomenclature are correct. Furthermore, we will only consider wild 
plains bison in conservation herds in this evaluation because we do not 
consider it to be within the intent of the Act to consider plains bison 
in commercial herds for listing.
Physical Description
    Bison are the largest native terrestrial mammal in North America 
(Reynolds et al. 2003, p. 1015). Wood bison are generally larger than 
the plains bison, but there is an overlap in size and dimensions 
between the two subspecies (Meagher 1986, p. 1). Body mass is 1,200 to 
2,000 pounds (lbs) (544 to 907 kilograms (kg)) in mature males and 700 
to 1,200 lbs (318 to 545 kg) in mature females (Meagher 1986, p. 1). 
Bison are brown, with longer hair over the forehead, neck, shoulder 
hump, and front-quarters; and shorter hair over the rear and tail 
(Meagher 1986, p. 1; Reynolds et al. 2003, p. 1009). The head is large 
and carried low on a short, thick neck (Meagher 1986, p. 1; Reynolds et 
al. 2003, p. 1009). Both sexes have short, black horns curving upward 
and inward, which are never shed (Meagher 1986, p. 1; Reynolds et al. 
2003, p. 1009).
Life History
    Sexual maturity most commonly occurs at 2 to 4 years of age; 
however, bulls do not usually breed until age 6 (Meagher 1986, p. 4). 
Female wild plains bison typically breed as 2-year olds and have their 
first calf at 3 years (Gates et al. 2010, p. 49). Gestation is 
approximately 285 days (Meagher 1986, p. 4). Calving season is from 
mid-April through May, with one calf being born; twins are rare 
(Meagher 1986, p. 4). Females typically breed until at least 16 years 
of age, although they may not breed in every year (Gates et al. 2010, 
p. 49).
    Wild plains bison are grazers throughout the year, taking mostly 
grasses and sedges (Meagher 1986, p. 5; Reynolds et al. 2003, p. 1034). 
Most free-ranging wild plains bison appear to be seasonally migratory 
(Meagher 1986, p. 5). Females of all ages, calves, and young males form 
herds (Meagher 1986, p. 6). Older bulls temporarily join these groups 
in late July to mid-August as rut approaches, but are otherwise found 
singly or in small groups (Meagher 1986, p. 6; Reynolds et al. 2003, p. 
1020). It is likely that the vast historical plains bison herds had a 
considerable impact on vegetation within their traditional ranges, 
through grazing, nutrient cycling, and physical disturbance (Reynolds 
et al. 2003, p. 1037). Prairie dog colonies (Cynomys spp.) are 
preferentially grazed by wild plains bison and also are used for 
grooming and wallowing (Reynolds et al. 2003, p. 1039).
Distribution
    Historically, habitat for the wild plains bison encompassed 
approximately 2.8 million square miles (mi2) (7.2 million 
square kilometers (km2), with approximately 1.9 million 
mi2 (5.0 million km2) west of the Mississippi 
River (Sanderson et al. 2008, p. 257). Wild plains bison were most 
abundant on the Great Plains, but their range also extended eastward 
into the Great Lakes region, beyond the Allegheny Mountains, and into 
Florida; westward into Nevada, the Cascade Mountains, and the Rocky 
Mountains; northward into mid-Alberta and Saskatchewan; and southward 
along the Gulf of Mexico into Mexico (Hornaday 1889, p. 377; Boyd 2003, 
p. 20; Reynolds et al. 2003, p. 1012; Gates et al. 2010, p. 56). Wild 
plains bison were eliminated west of the Rocky Mountains and east of 
the Mississippi River by the early 1800s (Halbert 2003, p. 4). By 1889, 
only a few wild plains bison remained in the Texas Panhandle, Colorado, 
Wyoming, Montana, and the western Dakotas, as well as a small number in 
captive herds (Hornaday 1889, p. 525). Today, wild plains bison occur 
in parks, preserves, other public lands, and on private lands 
throughout, and external to, their historical range.

[[Page 10302]]

Abundance
    Historical estimates regarding numbers of wild plains bison range 
from 30 to 75 million (Shaw 1995, p. 149). At the close of the Civil 
War, wild plains bison probably numbered in the tens of millions (Shaw 
1995, p. 150). Intensive market hunting for hides and meat occurred 
following the Civil War; by 1889, a minimum of 285 free-ranging wild 
plains bison and 256 captive plains bison were estimated to remain 
(Hornaday 1889, p. 525). Recent population estimates range from 400,000 
to 500,000, with approximately 20,500 animals in 62 conservation herds 
(Gates et al. 2010, p. 57) and the remainder in approximately 6,400 
commercial herds (Gates et al. 2010, p. 57).
Trends
    In the 1800s, wild plains bison declined from approximately 30 
million individuals rangewide to perhaps as few as 541. In the late 
1800s, a few concerned individuals undertook independent efforts to 
conserve the remaining plains bison (Hornaday 1889, pp. 458-464; Freese 
et al. 2007, p. 176). The American Bison Society formed in 1905 and 
pressed Congress to establish public bison herds in several locations, 
including Wichita Mountains National Wildlife Refuge (NWR) in Oklahoma, 
National Bison Range in Montana, Sullys Hill National Game Preserve in 
North Dakota, and Fort Niobrara NWR in Nebraska (Boyd 2003, p. 23). 
Yellowstone National Park (NP) and Elk Island National Park in Alberta, 
Canada, also participated in early efforts to conserve the wild plains 
bison. By 1970, an estimated 30,000 plains bison occurred in North 
America, approximately half in public conservation herds and half in 
private commercial herds (Boyd 2003, p. 23). By 2003, the number of 
plains bison in commercial herds increased dramatically to 
approximately 300,000 to 500,000 (Boyd 2003, p. 23; Halbert 2003, p. 
iii), while wild plains bison in conservation herds increased modestly 
to approximately 19,200 (Boyd 2003, p. 23). In 2007, there were 
approximately 420,000 plains bison in commercial herds in the United 
States and Canada (National Bison Association 2010). In 2008, there 
were an estimated 20,500 wild plains bison in conservation herds (Gates 
et al. 2010, p. 57). Population trends for wild plains bison in 
conservation herds appear stable to slightly increasing in recent 
years. The petitioners also note that population trends for wild plains 
bison in conservation herds have been stable since the 1930s, based 
upon information presented by Freese et al. (2007, p. 177) (Bailey and 
Bailey 2009, p. 15).
    The most recent information we have in our files regarding 
population status and trends of wild plains bison in conservation herds 
is presented in the following table. All information is from Boyd 
(2003, Appendix 1), with the exception of information for Rocky 
Mountain Arsenal NWR (Hastings 2011, pers. comm.) and House Rock Valley 
State Wildlife Area (Northern Arizona University 2009, p. 15).

                                 Table 1--Plains Bison Conservation Herd Status
                                   [The Nature Conservancy is abbreviated TNC]
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                  Herd                          Jurisdiction           Population               Trend
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Antelope Island State Park, UT.........  State.....................             600  Stable.
Badlands NP, SD........................  Federal...................             750  Stable.
Bear River State Park, WY..............  State.....................               8  Stable.
Blue Mounds State Park, MN.............  State.....................              56  Stable.
Buffalo Pound Provincial Park, SK......  Provincial (Canada).......              33  Stable.
Caprock Canyons State Park, TX.........  State.....................              40  Decreasing.
Chitina, AK............................  State.....................              38  Stable.
Clymer Meadow Preserve, TX.............  TNC & Private.............             320  Stable.
Copper River, AK.......................  State.....................             108  Stable.
Cross Ranch Nature Preserve, ND........  TNC.......................             140  Increasing.
Custer State Park, SD..................  State.....................            1100  Stable.
Daniels Park, CO.......................  Municipal.................              26  Stable.
Delta Junction, AK.....................  State.....................             360  Stable.
Elk Island NP, AB......................  Federal (Canada)..........             430  Stable.
Farewell Lake, AK......................  State.....................             400  Increasing.
Fermi National Accelerator Lab, IL.....  Federal...................              32  Stable.
Finney Game Refuge, KS.................  State.....................             120  Stable.
Fort Niobrara NWR, NE..................  Federal...................             352  Stable.
Fort Robinson State Park, NE...........  State.....................             500  Stable.
Genesee Park, CO.......................  Municipal.................              26  Stable.
Grand Teton NP & National Elk Refuge,    Federal & State...........             700  Increasing.
 WY (Jackson Herd).
Henry Mountains, UT....................  State.....................             279  Stable.
Hot Springs State Park, WY.............  State.....................              11  Stable.
House Rock Valley State Wildlife Area,   State.....................             276  Increasing.
 AZ.
Konza Prairie Biological Station, KS...  State & TNC...............             275  Stable.
Land Between the Lakes National          Federal...................             130  Decreasing.
 Recreation Area, KY.
Maxwell Wildlife Refuge, KS............  State.....................             230  Stable.
Medano-Zapata Ranch, CO................  TNC.......................            1500  Decreasing.
National Bison Range, MT...............  Federal...................             400  Stable.
Neal Smith NWR, IA.....................  Federal...................              35  Stable.
Niobrara Valley Preserve, NE...........  TNC.......................             473  Stable.
Ordway Prairie Preserve, SD............  TNC.......................             255  Stable.
Pink Mountain, BC......................  Provincial (Canada).......            1000  Stable.
Prairie State Park, MO.................  State.....................              76  Stable.
Primrose Air Weapons Range, AB & SK....  Provincial & Federal                   100  Increasing.
                                          (Canada).
Prince Albert NP, SK...................  Federal (Canada)..........             310  Increasing.
Raymond Wildlife Area, AZ..............  State.....................              72  Stable.
Riding Mountain NP, MB.................  Federal (Canada)..........              33  Increasing.
Rocky Mountain Arsenal NWR, CO.........  Federal...................              47  Increasing.

[[Page 10303]]

 
Sandhill Wildlife Area, WI.............  State.....................              15  Stable.
Santa Catalina Island, CA..............  Catalina Island                        225  Increasing.
                                          Conservancy.
Smoky Valley Ranch, KS.................  TNC.......................              45  Increasing.
Sullys Hill National Game Preserve, ND.  Federal...................              37  Stable.
Tallgrass Prairie Preserve, OK.........  TNC.......................            1500  Increasing.
Theodore Roosevelt NP, ND..............  Federal...................             850  Stable.
Wainwright Training Center, AB.........  Federal (Canada)..........              16  Stable.
Waterton Lakes NP, AB..................  Federal (Canada)..........              27  Stable.
Wichita Mountains NWR, OK..............  Federal...................             565  Stable.
Wildcat Hills State Recreation Area, NE  State.....................              10  Stable.
Wind Cave NP, SD.......................  Federal...................             375  Stable.
Yellowstone NP, WY, MT, ID.............  Federal...................            4000  Stable.
----------------------------------------------------------------------------------------------------------------

U.S. Department of the Interior's Bison Conservation Initiative
    The U.S. Department of Interior (USDOI) Bison Conservation 
Initiative provides a framework for managing wild plains bison within 
the USDOI (USDOI 2008, p. 3). This initiative specifies that the USDOI 
will: (1) Manage wild plains bison on their lands based on the best 
available science, seeking to restore them on appropriate landscapes; 
(2) apply adaptive management principles; (3) seek to develop genetic 
tests to maximize genetic diversity in herds; (4) seek to develop new 
techniques to diagnose, prevent, and control contagious diseases; and 
(5) work with interested parties (USDOI 2008, p. 2). One priority of 
the Initiative is to actively seek opportunities to increase existing 
herds to 1,000 or more wild plains bison, or establish new herds that 
can reach that size (USDOI 2008, p. 2). This priority describes numeric 
goals and allows the other seven priorities, including genetic 
diversity, disease, and introgression with cattle genes, to also be 
addressed. This initiative addresses the major concerns of wild plains 
bison management on USDOI lands, including genetics, disease, 
introgression with cattle genes, and the number and size of herds.
Private Management
    Forty-two wild plains bison conservation herds in the United States 
were described in 2003; of these, 22 are solely or jointly managed by 
States, 12 herds are solely or jointly managed by Federal agencies, 9 
herds are solely or jointly managed by private organizations, and 2 
herds are managed by municipalities (Boyd 2003, pp. 144-147). An 
additional eight herds are managed by Federal or provincial agencies in 
Canada (Boyd 2003, p. 147). Since 2003, 12 additional wild plains bison 
herds have been enumerated (Gates et al. 2010, p. 57). Initiatives for 
new wild herds also are under way, including herds managed by The 
Nature Conservancy (TNC) in Alberta and in South Dakota, by American 
Prairie Foundation and World Wildlife Fund in Montana, by the Cheyenne 
River Sioux Tribe in South Dakota, by the Lower Brule Sioux Tribe in 
South Dakota, and by Rosebud Sioux Tribe in South Dakota (Freese et al. 
2007, p. 182). Management of wild plains bison for conservation 
purposes appears to be active in both the private and public sectors. 
An additional 6,400 herds are managed for commercial purposes (Gates et 
al. 2010, p. 57).

Evaluation of Information for This Finding

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations at 50 CFR part 424 set forth the procedures for adding a 
species to, or removing a species from, the Federal Lists of Endangered 
and Threatened Wildlife and Plants. 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) of the Act:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    In making this 90-day finding, we evaluated whether information 
regarding the threats to the wild plains bison, as presented in the 
petition and other information available in our files, is substantial, 
thereby indicating that the petitioned action may be warranted. Our 
evaluation of this information is presented below.
    In considering what factors might constitute threats, we must look 
beyond the mere exposure of the species to the factor to determine 
whether the species responds to the factor in a way that causes actual 
impacts to the species. If there is exposure to a factor, but no 
response, or only a positive response, that factor is not a threat. If 
there is exposure and the species responds negatively, the factor may 
be a threat and we then attempt to determine how significant a threat 
it is. If the threat is significant, it may drive or contribute to the 
risk of extinction of the species such that the species may warrant 
listing as threatened or endangered as those terms are defined by the 
Act. This does not necessarily require empirical proof of a threat. The 
combination of exposure and some corroborating evidence of how the 
species is likely impacted could suffice. The mere identification of 
factors that could impact a species negatively may not be sufficient to 
compel a finding that listing may be warranted. The information shall 
contain evidence sufficient to suggest that these factors may be 
operative threats that act on the species to the point that the species 
may meet the definition of threatened or endangered under the Act. We 
found no information to suggest that threats are acting on the wild 
plains bison such that the species may become extinct now or in the 
foreseeable future.

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

Information Provided in the Petition
    The petitioners note the historical destruction and modification of 
plains habitat due to conversion to cropland and development of grazing 
land for cattle (Bailey and Bailey 2009, p. 15). They assert that there 
are ongoing habitat impacts from dam construction, cattle grazing, 
cropland conversion, tree invasion, wetland drainage, absence of

[[Page 10304]]

fire, subdivision of land for housing and other construction, and 
energy development (Bailey and Bailey 2009, p. 16). They further assert 
that with the possible exceptions of cattle grazing and dam 
construction, all of these activities are expected to increase in the 
foreseeable future (Bailey and Bailey 2009, p. 16). The petitioners 
also assert that a lack of populations on a minimum range size of 500 
mi\2\ (1,300 km\2\) of habitat threatens the wild plains bison, and 
only the Yellowstone herd meets this standard (Bailey and Bailey 2009, 
p. 21). The petitioners contend that the lack of suitable habitat is 
evidenced by dramatic declines in grassland birds (Bailey and Bailey 
2009, p. 22).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We agree that there have been historical destruction and 
modification of habitat due to conversion to cropland and development 
of grazing land for cattle. Information in our files indicates that 
cropland conversion, woody plant invasion, and cattle grazing have 
altered native grasslands (Ricketts et al. 2008, pp. 273-274), and 
cultivation has reduced the tallgrass portion of the Great Plains from 
approximately 168 million acres (ac) (68 million hectares (ha)) to less 
than 5 percent of that amount (Knapp et al. 1999, p. 39). American 
bison, including both plains bison and wood bison in conservation and 
commercial herds, currently occupy less than 1 percent of their 
historical range (Sanderson et al. 2008, p. 253).
    The petitioners do not provide citations to support their 
assertions regarding the present or threatened destruction, 
modification, or curtailment of habitat or range. Their arguments seem 
to rely on the losses of individuals and habitat that occurred in the 
1800s. We do not have information indicating that present or potential 
future impacts to habitat or range from dam construction, cattle 
grazing, cropland conversion, tree invasion, wetland drainage, absence 
of fire, subdivision, or energy development are threats to wild plains 
bison.
    Despite the historical loss of grasslands, much suitable habitat 
remains available, and additional habitat has often been only degraded 
rather than converted. There is potential for rapid recovery of these 
degraded grasslands (Ricketts et al. 2008, p. 288). Boyd (2003, pp. 95, 
148-151) states that a lack of suitable habitat is limiting wild plains 
bison recovery, but also notes that 25 out of 50 wild plains bison 
herds that she evaluated have potential for expansion. The petitioners 
note that wild plains bison restoration opportunities exist on public 
lands managed by the USDOI and the U.S. Department of Agriculture 
(USDA), often mixed with State public lands (Bailey and Bailey 2009, p. 
10). National Grasslands managed by the U.S. Forest Service (USFS) 
account for nearly 4 million ac (1.6 million ha), with some parcels of 
suitable habitat currently large enough to maintain wild plains bison 
herds (Olson 1997, p. 4; Ricketts et al. 2008, p. 275). Native American 
Tribes also have large tracts of suitable habitat that could support 
wild plains bison (Boyd 2003, p. 106; Freese et al. 2007, p. 181).
    When determining whether a species should be listed, we examine the 
current status of a species, which necessitates examining the species 
in its current range and analyzing current and future threats to the 
remainder of the species' distribution. The information the petitioner 
presented on lost historical range, by itself, does not provide 
substantial information that listing the wild plains bison may be 
warranted. However, loss of historical range may be relevant to the 
analysis of the current and future viability of the species, if the 
factors that caused the past decline are shown to be operating on 
populations within the current range. Once wild plains bison were 
protected from market hunting, beginning in the late 1800s, their 
numbers rapidly increased (Gates et al. 2010, p. 9). We do not believe 
that the market hunting that led to the precipitous decline of wild 
plains bison in the 1800s is likely to be repeated. Habitat is 
currently available to accommodate additional herds. Furthermore, 
recent stable-to-slightly increasing population trends in conservation 
herds do not indicate that habitat is a limiting factor for wild plains 
bison.
    The petitioners did not provide any citations and we do not have 
any information in our files to support a proposed minimum of 500 mi\2\ 
(1,300 km\2\) of habitat necessary to maintain an ecologically 
significant herd. The petitioners state that only the Yellowstone herd 
meets this proposed standard, and the Henry Mountain herd nearly meets 
it. We are aware of three additional wild plains bison herds that 
occupy more than 500 mi\2\ (1,300 km;\2\) of habitat: Farewell Lake in 
Alaska, Pink Mountain in British Columbia, and Primrose Air Weapons 
Range in Alberta and Saskatchewan. The first two herds are outside of 
the historical range of the plains bison, and the Primrose herd is at 
the periphery of the historical range. Nevertheless, five herds meet or 
exceed 500 mi\2\ (1,300 km\2\). We agree that, in general, the larger 
the extent of habitat available, the greater the ecological 
significance. However, we believe that herds residing on less than 500 
mi\2\ (1,300 km\2\) also can have ecological significance. We have no 
evidence that indicates that wild plains bison in herds occupying less 
than 500 mi\2\ (1,300 km\2\) of habitat are threatened from lack of 
habitat. Most herds, whether occupying more or less than this amount, 
exhibit stable to increasing population trends. Therefore, we do not 
believe that there is substantial information indicating that listing 
may be warranted due to a lack of herds occupying at least 500 mi\2\ 
(1,300 km\2\) of habitat.
    The petitioners also contend that the lack of suitable habitat is 
evidenced by dramatic declines in grassland birds (Bailey and Bailey 
2009, p. 22). Grassland bird abundance and diversity is one indicator 
of a healthy ecosystem, as the petitioners suggest, but addressing 
their population trends is beyond the scope of this document. We have 
no evidence that there is a relationship between grassland bird 
abundance and wild plains bison persistence.
    In summary, we find that the information provided in the petition, 
as well as other information in our files, does not present substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted due to present or threatened destruction, 
modification, or curtailment of habitat or range.

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

Information Provided in the Petition
    The petitioners do not assert that overutilization is a threat to 
the wild plains bison. They do note that, historically, wild plains 
bison numbered in the tens of millions, but were subsequently reduced 
to near extinction (Bailey and Bailey 2009, p. 3). They also suggest 
that hunting may be an appropriate management tool (Bailey and Bailey 
2009, p. 11).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We agree that there was a dramatic historical decline in numbers of 
wild plains bison due to market hunting and, to a lesser extent, 
subsistence hunting and recreational shooting (Hornaday 1889, pp. 499-
525; Boyd 2003, p. 22; Freese et al. 2007, p. 176; IUCN 2008). However, 
market hunting for wild plains bison ended in 1884 (Hornaday

[[Page 10305]]

1889, p. 513) and is no longer a factor. We also agree that hunting can 
be an appropriate management tool. Limited authorized hunting of wild 
plains bison currently occurs on three public herds in the contiguous 
United States, four herds in Alaska, and five herds in Canada (Reynolds 
et al. 2003, pp. 1047-1048).
    In summary, we find that the information provided in the petition, 
as well as other information in our files, does not present substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted due to overutilization for commercial, 
recreational, scientific, or educational purposes.

C. Disease or Predation

Information Provided in the Petition
    The petitioners note that wild plains bison in the Greater 
Yellowstone Ecosystem are infected with brucellosis (Brucella abortus), 
which they assert is a minor direct threat, but indirectly severely 
limits the herd because of limitations imposed by disease management 
(Bailey and Bailey 2009, pp. 8, 21). They note that management for 
brucellosis can involve capture, retention, handling, culling, hazing, 
and vaccination and assert that this interferes with natural selection, 
may enhance disease transmission, alters age structure, and limits herd 
numbers (Bailey and Bailey 2009, p. 21). They also contend that 
vaccinations in general subvert natural selection and promote 
domestication (Bailey and Bailey 2009, p. 21). The petitioners did not 
cite predation as a threat.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    Brucellosis is a bacterial infection that occurs in cattle, bison, 
and other mammals (Cook et al. 2004, p. 254; Seabury et al. 2005, p. 
104). It has been eradicated from all commercial bison herds and most 
wild bison herds in the United States through improved management 
(Seabury et al. 2005, p. 105).
    Wild plains bison and elk (Cervus elaphus) in the Greater 
Yellowstone Area are the last remaining reservoirs of brucellosis in 
the United States (Aune et al. 2007, p. 205). Brucellosis is not a 
direct threat, because reproduction is only marginally limited, but 
wild plains bison can be indirectly affected by the potential risk that 
infected bison herds pose to the livestock industry. Wild plains bison 
leaving Yellowstone NP in the winter on the northern and western 
boundaries are subject to hazing, vaccination, radio-telemetry, 
capture, testing, and slaughter of animals that test positive for the 
disease (Aune et al. 2007, p. 206). Transmission of brucellosis from 
bison to cattle has been demonstrated in captive studies, but there are 
no confirmed cases of transmission in the wild (Boyd 2003, p. 80).
    In December 2000, following more than 10 years of collaborative 
planning, the USDOI (NPS) and the USDA (Animal and Plant Health 
Inspection Service and USFS) signed a Record of Decision for a joint 
bison management plan for Yellowstone and the State of Montana (USDOI 
and USDA 2000, p. 3). The intent of this plan is to preserve 
Yellowstone's wild plains bison and minimize the potential risk of 
transmission of brucellosis from bison to cattle (USDOI and USDA 2000, 
p. 6). This separation is attempted through hazing of wild plains bison 
back into Yellowstone, followed by, when necessary, capture, testing, 
and slaughter or release of captured bison, depending on test results 
(USDOI and USDA 2000, p. 6). Agencies allow wild plains bison outside 
of Yellowstone in areas without cattle (USDOI and USDA 2000, p. 11). If 
severe winter conditions exist and wild plains bison numbers drop below 
2,300, the agencies will temporarily halt slaughter of infected bison 
(USDOI and USDA 2000, pp. 13, 34). This plan is a comprehensive 
approach to protecting wild plains bison in the Park and minimizing the 
risk of brucellosis transmission to cattle grazing on adjacent lands. 
The NPS has recently proposed a remote vaccination program for wild 
plains bison in Yellowstone that would minimize capture and handling of 
bison (NPS 2010, p. iii).
    Brucellosis has been eradicated from all wild plains bison herds in 
the United States, with the exception of the two herds in the Greater 
Yellowstone Area (Yellowstone and Jackson herds). The Jackson herd is 
jointly managed by Grand Teton National Park and the Service's National 
Elk Refuge. Disease management is ongoing in these two herds. The 
petitioners contend that the hazing, capture, vaccination, and culling 
that may occur subvert natural selection, may enhance disease 
transmission, alter age structure, and limit herd numbers (Bailey and 
Bailey 2009, p. 21). However, the petitioners did not provide evidence 
to support that these activities are a threat to the status of the 
species such that the species may warrant listing as threatened or 
endangered. Furthermore, recent stable-to-increasing population trends 
do not indicate that management for brucellosis is a limiting factor 
for wild plains bison in the Greater Yellowstone Area. Additionally, 
disease management is often an essential aspect of wildlife management.
    In summary, we find that the information provided in the petition, 
as well as other information in our files, does not present substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted due to disease or predation.

D. The Inadequacy of Existing Regulatory Mechanisms

Information Provided in the Petition
    The petitioners assert that existing Federal and State regulatory 
mechanisms for wild plains bison conservation are inadequate (Bailey 
and Bailey 2009, pp. 16-19). They cite the Interagency Bison Management 
Plan for Yellowstone NP, the USDOI's Bison Conservation Initiative, 
Charles M. Russell NWR, National Grasslands management, and legal 
designations by the States as examples of inadequate regulations where 
more could be done to restore wild plains bison. They also assert that 
management by private programs is inadequate (Bailey and Bailey 2009, 
p. 19).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We consider plans and initiatives to be voluntary agreements that 
provide guidance for better managing wild plains bison, rather than 
regulatory mechanisms. Therefore, we discuss the Interagency Bison 
Management Plan for Yellowstone under Factor C, because it focuses on 
disease. The USDOI's Bison Conservation Initiative and private programs 
are discussed under Background. Management of wild plains bison on NWRs 
and National Grasslands, and legal designations by States, are 
discussed under this factor. We evaluate the inadequacy of existing 
regulatory mechanisms from the standpoint of the other factors. If 
there is not substantial information that listing a species may be 
warranted due to another factor, then the regulations affecting that 
factor cannot be considered inadequate.
Charles M. Russell National Wildlife Refuge
    The National Wildlife Refuge System Administration Act established 
the National Wildlife Refuge System and identified a primary mission of 
wildlife conservation. The Service manages over 500 National Wildlife 
Refuges and their satellites. Wild plains bison

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conservation is a National Wildlife Refuge System priority (Jones and 
Roffe 2008, p. 5). Purposes of wild plains bison management include: 
(1) To fulfill a legal mandate as part of establishing a Refuge, (2) to 
conserve bison, (3) to provide education and recreation for the public, 
(4) to manage habitat, (5) to protect cultural or historic 
significance, and (6) to carry out research (Jones and Roffe 2008, p. 
5). Charles M. Russell NWR is one of eight National Wildlife Refuges in 
the contiguous United States that include wild plains bison management 
among their priorities (Jones and Roffe 2008, p. 3). Wild plains bison 
management is at an early stage at Charles M. Russell NWR, with only a 
small number of bison currently present. The other refuges with wild 
plains bison are Wichita Mountains NWR in Oklahoma (herd founding date 
1907), the National Bison Range in Montana (herd founding date 1908), 
Fort Niobrara NWR in Nebraska (two herds, founding dates 1913 and 
1919), Sullys Hill National Game Preserve in North Dakota (herd 
founding date 2006), Neal Smith NWR in Iowa (herd founding date 1996), 
the National Elk Refuge in Wyoming (jointly managed with Grand Teton 
National Park; herd founding date 1948), and Rocky Mountain Arsenal NWR 
in Colorado (herd founding date 2007). The Service has a strong and 
active commitment to wild plains bison conservation and ecological 
restoration, and we do not believe that there is substantial 
information indicating that listing may be warranted due to perceived 
inadequacies in refuge planning at Charles M. Russell NWR.
National Grasslands Management
    The USFS administers 20 National Grasslands consisting of 
approximately 3.8 million ac (1.6 million ha) in 13 States, but the 
grasslands are primarily in Colorado, North Dakota, South Dakota, and 
Wyoming (Olson 1997, p. 4). According to the Federal Land Policy and 
Management Act, these grasslands are to be administered under sound and 
progressive principles of land conservation and multiple use (36 CFR 
part 213). Approximately 189 million ac (77 million ha) of National 
Forests also are managed by the USFS. We believe that several National 
Grasslands and National Forests are of sufficient size and habitat type 
to support wild plains bison. Wild plains bison on USFS lands are 
typically the result of overflow from herds on NPS lands (such as the 
Yellowstone herd) (USDOI and USDA 2000, p. 3), or are State-owned herds 
(such as the House Rock Valley herd) (Northern Arizona University 2009, 
p. 1). These wild plains bison are adequately protected by Federal laws 
and regulations mandating how USFS lands are managed. We do not believe 
that there is substantial information indicating that listing may be 
warranted due to lack of actions on the part of the USFS.
Legal Designations
    Plains bison fall into an unusual legal classification that can 
complicate understanding the management intent for a given herd (Freese 
et al. 2007, p. 181). Their legal status can be either domestic 
livestock or wildlife among various Federal, State, and provincial 
jurisdictions across North America (Gates et al. 2010, p. 66). Plains 
bison are managed as captive or free-ranging wildlife on National Parks 
and National Wildlife Refuges. They have dual status (herds may be 
considered domestic livestock or wildlife, depending on whether they 
are commercial or conservation herds) in Alaska; Arizona; Idaho; Utah; 
Missouri; Montana; New Mexico; South Dakota; Texas; Wyoming; British 
Columbia; Saskatchewan; and Chihuahua, Mexico (Gates et al. 2010, pp. 
66-73). Plains bison are classified solely as domestic livestock in 
Colorado, Illinois, Iowa, Kansas, Louisiana, Minnesota, Nebraska, North 
Dakota, Nevada, Oklahoma, Alberta, and Manitoba, regardless of whether 
they are in commercial or conservation herds (Gates et al. 2010, pp. 
66-73). Nevertheless, wild plains bison that are classified as domestic 
livestock and are in conservation herds are managed for purposes of 
wildlife conservation, and not for production of meat and other 
commodities. Therefore, they are not adversely affected by their legal 
designation. A more uniform and straightforward classification of 
plains bison could simplify the regulatory status by which they are 
managed, but we do not believe that there is substantial information 
indicating that listing may be warranted due to their legal status.
Summary of Factor D
    In summary, we find that the information provided in the petition, 
as well as other information in our files, does not present substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted due to the inadequacy of existing regulatory 
mechanisms.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Information Provided in the Petition
    The petitioners assert that loss of genetic diversity threatens the 
wild plains bison, and that a minimum herd size of 2,000 animals is 
required to provide genetic diversity, noting that only 1 herd 
(Yellowstone) fulfills this requirement (Bailey and Bailey 2009, p. 
19). They contend that management activities such as roundups, culling, 
protection from predators, pasture rotation, supplemental feeding, and 
vaccination lead toward domestication and genomic extinction (Bailey 
and Bailey 2009, p. 20).
    The petitioners assert that introgression (hybridization) with 
cattle genes threatens the wild plains bison, and that only seven herds 
have been found to be free of cattle genes (Bailey and Bailey 2009, p. 
20). The petitioners also allude to impacts from climate change, noting 
that the presence of at least one wild plains bison herd in each of the 
four major ecotypes could provide redundancy, resiliency, and perhaps 
genetic adaptations in the event of global warming (Bailey and Bailey 
2009, pp. 11-12).
Evaluation of Information Provided in the Petition and Available in 
Service Files
Loss of Genetic Diversity
    Preservation of genetic diversity in the wild plains bison is 
essential to its conservation (Boyd 2003, p. 60). Genetic diversity 
provides flexibility for evolutionary change and adaptation (Gardipee 
2007, p. 1; Gates et al. 2010, p. 19). The population decline for wild 
plains bison was severe--from tens of millions to possibly as low as 
541 animals. Demographic bottlenecks such as this, and resultant 
founder effects, genetic drift, and inbreeding, can reduce genetic 
diversity (Boyd 2003, p. 60). The consequences of a bottleneck depend 
on the severity of the decline and how quickly the population recovers 
(Boyd 2003, p. 60).
    The small numbers of plains bison remaining after the bottleneck 
resulted in very few founders and the possibility for genetic drift, 
which involves the random change in gene frequencies leading to the 
loss of certain unique DNA sequences in a particular gene type (allele) 
from one generation to the next (Boyd 2003, pp. 60-61). Small 
populations also may experience inbreeding or highly skewed gender 
ratios, which can lead to the expression of deleterious alleles, the 
decreased presence of both dominant and

[[Page 10307]]

recessive alleles (decreased heterozygosity (decreased hybridization of 
genes; an indicator of poor genetic health), lower fecundity, and 
developmental defects (Boyd 2003, p. 61). However, the duration of the 
bottleneck for plains bison was relatively short (Halbert 2003, p. 52), 
and the population recovered quickly (Boyd 2003, p. 60). Pre-bottleneck 
wild plains bison numbers, movement, and distribution suggest 
widespread interbreeding and significant genetic homogeneity among 
continental populations. The selection of captive and wild plains bison 
used in early foundation herds represented a large portion of the 
historical range and, therefore, likely captured a large portion of 
pre-bottleneck genetic variation (Halbert 2003, p. 52). Today's wild 
plains bison have substantially greater genetic variation than reported 
for other mammalian species that have experienced similar bottlenecks 
(Halbert 2003, p. 51). In general, populations of wild plains bison 
that have been tested display a moderately high level of overall 
genetic diversity, with notable differences in overall allelic 
variation and heterozygosity (Halbert 2003, p. 60).
    A minimum viable population (MVP) is the smallest population size 
that provides a high probability (typically 95 percent) of persistence 
for a given period of time (typically, 100 years) (Boyd 2003, p. 36). 
Large-bodied species with a long lifespan tend to experience less 
severe population fluctuations than smaller, short-lived species (Boyd 
2003, p. 37). Consequently, a lower MVP is typical for large, long-
lived species. The Canadian National Wood Bison Recovery Team uses a 
MVP of 400 for wood bison (Boyd 2003, p. 38). More recently, the IUCN 
considered wild plains bison populations to be viable if they were 
greater than 1,000 animals (IUCN 2008). Freese et al. (2007, p. 180) 
suggest that in consideration of exotic diseases and climate change, a 
prudent goal would be retention of at least 95-percent allelic 
diversity for 200 years, which would require a MVP of 2,000 animals. We 
are aware of 15 conservation herds with at least 400 wild plains bison, 
4 conservation herds with at least 1,000 wild plains bison (Custer 
State Park in South Dakota, Medano-Zapata Ranch in Colorado, Pink 
Mountain in British Colombia, and Yellowstone), and 1 conservation herd 
with more than 2,000 wild plains bison (Yellowstone). Selectively 
moving animals in smaller herds from one herd to another as is still 
frequently done in conservation herds, and can counter the effects of 
genetic drift and maintain viability (Halbert 2003, p. 153; Jones and 
Roffe 2008, p. 8). The USDOI has a priority of increasing their 
existing herds to at least 1,000 animals, or establishing new herds 
that can reach that size (USDOI 2008, p. 2).
    All wild plains bison herds have experienced some degree of 
management, ranging from initial establishment of the herd to more 
intensive management activities such as roundups, culling, protection 
from predators, pasture rotation, supplemental feeding, and 
vaccination. We recognize that maximizing the wildness of the plains 
bison is important for the maintenance of genetic diversity, but also 
believe that continued judicious management is necessary for long-term 
survival in the modern world. For example, in an effort to minimize 
capture and handling of wild plains bison in Yellowstone, the NPS is 
considering the use of air rifles to deliver brucellosis vaccines 
remotely (NPS 2010, p. iii).
    Populations of wild plains bison that have been tested display a 
moderately high level of overall genetic diversity. Selective movement 
of animals between herds, as currently practiced, can help maintain 
that genetic diversity. We do not believe that there is substantial 
information indicating that listing may be warranted due to a loss of 
genetic diversity.
Introgression With Cattle Genes
    Introgression was caused by hybridization between plains bison and 
cattle, followed by breeding of the hybrid offspring to at least one of 
their respective parental populations (Gates et al. 2010, p. 22). The 
introgressed or alien DNA replaced sections of the original DNA, 
thereby affecting the genetic integrity of the wild plains bison (Gates 
et al. 2010, p. 22). Most genetic studies we are aware of have been 
conducted on conservation herds (Polziehn et al. 1995, p. 1638; Ward et 
al. 1999, p. 52; Boyd 2003, p. 68; Halbert 2003, p. 70; Halbert et al. 
2005, pp. 2349-2350).
    When plains bison were at their lowest numbers in the late 1800s, a 
few individuals established small captive foundation herds that saved 
the subspecies from extinction. Each of these herds was, to some 
extent, used to either experimentally create bison-domestic cattle 
crosses, or supplemented with plains bison from herds involved in such 
experiments (Halbert et al. 2005, p. 2344). Controlled breeding of male 
plains bison to female domestic cattle has been recorded extensively, 
although the birth rate of first-generation offspring is very low 
(Halbert et al. 2005, p. 2344), and male offspring are usually sterile 
(Meagher 1986, p. 6). Behavioral constraints typically prevent domestic 
bulls from mating with female bison (Boyd 2003, p. 67). Due to the 
sterility of male offspring and the lack of domestic bulls that 
successfully breed with female bison, there is no evidence of male-
linked or Y-chromosome cattle gene introgression in bison (Boyd 2003, 
p. 67). However, maternally inherited DNA, known as mitochondrial DNA 
(mtDNA), and nuclear DNA (contributed by either parent) introgression 
have been demonstrated (Polziehn et al. 1995, p. 1641; Ward et al. 
1999, p. 51; Boyd 2003, p. 67; Halbert 2003, p. 13), which indicates 
that many plains bison contain some cattle DNA from experimental 
crosses conducted in the past.
    The proportion of cattle DNA that has been measured in introgressed 
individuals and herds is typically quite low, ranging from 0.56 to 1.8 
percent (Polziehn et al. 1995, p. 1642; Halbert et al. 2005, p. 2343). 
However, estimates based on extrapolation from portions of genomes 
sampled, to the entire genome, to all animals in a herd should be 
considered only as approximations (Roffe and Jones 2008, p. 1). The 
petitioners assert that seven herds have been found free of cattle 
genes (Bailey and Bailey 2009, p. 20). We are aware that very few herds 
lack evidence of at least some cattle allele introgression. Based upon 
the information currently available, the following wild plains bison 
conservation herds show no evidence of introgression: Elk Island 
National Park in Alberta, Jackson herd (Grand Teton National Park--
National Elk Refuge) in Wyoming, Henry Mountains in Utah, Sullys Hill 
National Game Preserve in North Dakota, Wind Cave National Park in 
South Dakota, and Yellowstone (Halbert and Derr 2007, p. 8). One 
private herd, Castle Rock in New Mexico, also shows no evidence of 
introgression (Freese et al. 2007, p. 182). The Jackson and Sullys Hill 
herds have not been adequately sampled to allow for statistical 
confidence (Halbert and Derr 2007, p. 8), and many other herds have not 
yet been tested. As techniques improve and more extensive sampling 
occur, some herds previously without evidence of introgression may be 
found to contain introgressed alleles.
    Some conservation herds known to have low levels of cattle 
introgression also contain unique or rare plains bison genetic 
diversity (Halbert 2003, p. 98; Gates et al. 2010, p. 23). To minimize 
genetic loss and not exacerbate the effects of the historical 
bottleneck on the wild plains bison, managers feel that

[[Page 10308]]

this unique genetic background should be conserved, while herds with no 
evidence of introgression should be maintained in isolation from 
introgressed populations (Halbert 2003, p. 94). Issues of introgression 
and unique genetic diversity are both considered in management of wild 
plains bison.
    The presence of cattle DNA in the genetic makeup of wild plains 
bison appears widespread, but occurs at low levels. Conservation herds 
are managed according to their genetic background, so as to maintain 
genetic diversity and introgression-free herds. We expect the frequency 
of cattle DNA to remain low in conservation herds. Wild plains bison 
from introgressed herds conform morphologically, behaviorally, and 
ecologically to the scientific taxonomic description of the native 
subspecies. Some wild plains bison herds with evidence of cattle 
introgression also contain valuable genetic diversity that is not found 
elsewhere and should be conserved. We do not believe that there is 
substantial information indicating that listing may be warranted due to 
introgression with cattle genes.
Climate Change
    No information on the direct relationship between climate change 
and wild plains bison was provided by the petitioners or is available 
in our files. According to the Intergovernmental Panel on Climate 
Change (IPCC 2007, p. 6), ``warming of the climate system is 
unequivocal, as is now evident from observations of increases in global 
average air and ocean temperatures, widespread melting of snow and ice, 
and rising global average sea level.'' Average Northern Hemisphere 
temperatures during the second half of the 20th century were very 
likely higher than during any other 50-year period in the last 500 
years, and likely the highest in at least the past 1,300 years (IPCC 
2007, p. 6). It is very likely that over the past 50 years, cold days, 
cold nights, and frosts have become less frequent over most land areas, 
and hot days and hot nights have become more frequent (IPCC 2007, p. 
6). It is likely that heat waves have become more frequent over most 
land areas, and the frequency of heavy precipitation events has 
increased over most areas (IPCC 2007, p. 6).
    Changes in the global climate system during the 21st Century are 
likely to be larger than those observed during the 20th Century (IPCC 
2007, p. 19). For the next 2 decades, a warming of about 0.2 
[deg]Celsius ([deg]C) (0.4 [deg]Fahrenheit ([deg]F)) per decade is 
projected (IPCC 2007, p. 19). Afterward, temperature projections 
increasingly depend on specific emissions scenarios (IPCC 2007, p. 19). 
Various emissions scenarios suggest that by the end of the 21st 
Century, average global temperatures are expected to increase 0.6 to 
4.0 [deg]C (1.1 to 7.2 [deg]F), with the greatest warming expected over 
land (IPCC 2007, p. 20). The IPCC (2007, pp. 22, 27) report outlines 
several scenarios that are virtually certain or very likely to occur in 
the 21st Century including: (1) Over most land, there will be warmer 
days and nights, and fewer cold days and nights, along with more 
frequent hot days and nights; (2) areas affected by drought will 
increase; and (3) the frequency of warm spells and heat waves over most 
land areas will likely increase. The IPCC predicts that the resiliency 
of many ecosystems is likely to be exceeded this century by an 
unprecedented combination of climate change, associated disturbances 
(e.g., flooding, drought, wildfire, and insects), and other