Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Yellowstone National Park Bison Herd as Endangered, 45717-45722 [E7-16004]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 72, Number 157 (Wednesday, August 15, 2007)]
[Proposed Rules]
[Pages 45717-45722]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-16004]



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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List the Yellowstone National Park Bison Herd as 
Endangered

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 (Service), announce a 
90-day finding on a petition to list the Yellowstone National Park 
(YNP) bison herd as endangered under the Endangered Species Act of 
1973, as amended (Act). On the basis of our review of the petition and 
information readily available in our files, we have determined that 
there is substantial information indicating that the YNP bison herd may 
meet the criteria of discreteness and significance as defined by our 
policy on distinct vertebrate population segments (DPS). However, we 
have also determined that there is not substantial information 
indicating that listing the YNP bison herd under the Act may be 
warranted throughout all or a significant part of its range. We will 
not initiate a status review in response to this petition. We ask the 
public to submit to us any new information that becomes available 
concerning the status of the YNP bison herd or threats to it or its 
habitat at any time. This information will help us monitor and 
encourage the conservation of the species.

DATES: The finding announced in this document was made on August 15, 
2007. New information concerning this species may be submitted for our 
consideration at any time.

ADDRESSES: Data, information, comments, or questions concerning this 
petition finding should be submitted to the Assistant Regional 
Director, Ecological Services, U.S. Fish and Wildlife Service, 134 
Union Boulevard, Suite 645, Lakewood, Colorado 80228. The petition 
finding and supporting information will be available for public 
inspection, by appointment, during normal business hours at the above 
address. The petition and finding are available on our Web site at 
https://r6.fws.gov/mammals/bison.

FOR FURTHER INFORMATION CONTACT: Michael Stempel, Assistant Regional 
Director, Ecological Services, U.S. Fish and Wildlife Service (see 
ADDRESSES section) (telephone 303-236-4253; facsimile 303-236-0027).

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(A) of the Endangered Species Act of 1973, as 
amended (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 to indicate 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 at 
the time we make the determination. 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 this finding promptly in the 
Federal Register.
    Our standard for substantial 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 information was presented, we 
are required to promptly commence a review of the status of the 
species.
    In making this finding, we relied on information provided by the 
petitioners and information otherwise available in our files, and 
evaluated that information in accordance with 50 CFR 424.14(b). Our 
process of coming to a 90-day finding under section 4(b)(3)(A) of the 
Act and section 424.14(b) of our regulations is limited to a 
determination of whether the information in the petition meets the 
``substantial information'' threshold.
    Mr. James Horsley of Moorhead, Minnesota, filed a petition dated 
January 5, 1999, with the Secretary of the Interior to list the ``herd 
of buffalo at the Yellowstone National Park'' ``because it is 
endangered in a significant portion of its range.'' Mr. Horsley 
requested that the Service list the herd as a subspecies or ``distinct 
population group,'' and to designate critical habitat in and adjacent 
to YNP. The Service received the petition on February 11, 1999. Action 
on this petition has been precluded until now because of higher 
priority listing actions. This finding does not consider critical 
habitat, which would only arise with a positive 12-month finding.

Biology and Distribution

    The bison (also referred to as the American buffalo) is a member of 
the family Bovidae, which includes domestic cattle. Two subspecies of 
bison are currently recognized in North America--the plains bison 
(Bison bison bison) and the wood bison (Bison bison athabascae) (Boyd 
2003, pp. 28-31). The species once ranged across central and western 
North America, but market hunting nearly extirpated the herds by the 
1880s.
    Numerous Federal, State, and private bison herds currently exist in 
the United States, but YNP is the only area in the United States where 
bison have existed in the wild state since prehistoric times (Gates et 
al. 2005, p. 92). Boyd (2003, p. 38) estimated the plains bison 
population in North America at 500,000, and identified 50 herds 
(containing approximately 19,200 head) currently being managed with 
clear conservation objectives.
    Many of the numerous bison herds currently extant in the United 
States and Canada were reconstituted from stock that was used to 
develop bison-cattle hybrids (Boyd 2003, p. 23). Research on 11 Federal 
herds revealed that the bison herd in YNP was 1 of 3 that showed no 
evidence of genetic introgression with cattle (Halbert 2003, pp. 86-87) 
based on the alleles examined. (Introgression occurs when the genes of 
one species infiltrate the genes of another through repeated 
crossings.) The other two herds were Wind Cave National Park in South 
Dakota and Grand Teton National Park in Wyoming (Halbert 2003, p. 87), 
although the Grand Teton sample size was small so confidence in the 
results is lower than that for Wind Cave. More recently, the bison herd 
at Sully's Hill National Game Preserve in North Dakota has been sampled 
and is not known to be introgressed, although the sample size was small 
(Roffe 2005).
    Halbert (2003, pp. 44-45) found only four of the Federal herds made 
positive contributions to overall bison genetic diversity (measured in 
terms of allelic richness and gene diversity). Those herds were: YNP, 
National Bison Range (Montana), Wichita Mountains National Wildlife 
Refuge (Oklahoma), and Wind Cave.
    The winter 2005-2006 count of the YNP bison herd estimated the herd 
size at 3,546 bison (Geremia and Wallen 2006), and the most recent 
summer count estimated the herd size at 4,500 bison (Wallen 2007).

Subspecies

    The bison in Yellowstone National Park are considered to be plains 
bison

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(Bison bison bison). As mentioned previously, Boyd (2003, p. 38) 
estimated the plains bison population in North America at 500,000, and 
identified 50 herds (containing approximately 19,200 head) currently 
being managed with clear conservation objectives. Given the abundance 
and management status of the subspecies, we have concluded that the 
petition has not presented substantial information indicating that its 
listing under the Act may be warranted.

Distinct Vertebrate Population Segment

    The petitioner asked us to list the YNP bison herd as a ``distinct 
population group.'' We assume that the petitioner meant a Distinct 
Vertebrate Population Segment (DPS) for purposes of listing under the 
Act. Under section 3(15) of the Act, we may consider for listing any 
species, subspecies, or, for vertebrates, any DPS of these taxa. In 
determining whether an entity constitutes a DPS, and is therefore 
listable under the Act, we follow the Policy Regarding the Recognition 
of Distinct Vertebrate Population Segments Under the Endangered Species 
Act (DPS Policy) (61 FR 4722; February 7, 1996). Under our DPS Policy, 
we must address three analytical steps prior to listing a possible DPS: 
(1) The discreteness of the population segment in relation to the 
remainder of the taxon; (2) the significance of the population segment 
to the taxon to which it belongs; and (3) the population segment's 
conservation status in relation to the Act's standards for listing 
(i.e., is the population segment, when treated as if it were a species, 
endangered or threatened) (61 FR 4722, February 7, 1996). This finding 
considers whether the petition states a reasonable case that the 
petitioned population may be a DPS.

Discreteness

    Under the DPS Policy, a population segment of a vertebrate species 
may be considered discrete if it satisfies either one of the following 
two conditions: (1) It is markedly separated from other populations of 
the same taxon as a consequence of physical, physiological, ecological, 
or behavioral factors. Quantitative measures of genetic or 
morphological discontinuity may provide evidence of this separation; or 
(2) it is delimited by international governmental boundaries within 
which significant differences in control of exploitation, management of 
habitat, conservation status, or regulatory mechanisms exist (61 FR 
4722, February 7, 1996).

Information Provided in the Petition on Discreteness

    The petitioner asserts that the YNP bison ``herd is the only wild, 
unfenced buffalo herd in the nation,'' but no specific citations are 
provided to support this conclusion. Information in our files support 
the conclusion that the YNP bison population is the only herd in the 
United States that has remained in a wild state since prehistoric times 
(Gates et al. 2005, p. 93). All other bison in the United States are 
reconstituted herds and are confined with fencing, or otherwise range 
restricted. Individuals from the Jackson bison herd in Grand Teton 
National Park and the National Elk Refuge have been known to migrate 
north into YNP, but this is a rare occurrence (Gates et al. 2005, p. 
109). Therefore, we find that the YNP bison herd may be discrete from 
other members of the taxon Bison bison because of physical distance and 
barriers.

Significance

    Under our DPS Policy, in addition to our consideration that a 
population segment is discrete, we consider its biological and 
ecological significance to the taxon to which it belongs. This 
consideration may include, but is not limited to: (1) Evidence of the 
persistence of the discrete population segment in an ecological setting 
that is unique or unusual for the taxon; (2) evidence that loss of the 
population segment would result in a significant gap in the range of 
the taxon; (3) evidence that the population segment represents the only 
surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historical range; and 
(4) evidence that the discrete population segment differs markedly from 
other populations of the species in its genetic characteristics (61 FR 
4721; February 7, 1996).

Information Provided in the Petition on Significance

    The petitioner asserts that the YNP bison herd is significant 
within the meaning of our DPS policy because it is the last wild, 
unfenced herd in the United States, and exhibits quasi-migratory 
behavior when members of the herd leave YNP during the winter in search 
of food. The petition also asserts that the herd may be a unique hybrid 
of the wood and plains bison, and the herd has historical and cultural 
significance to Native Americans. No citations are provided to 
substantiate these statements.
    (1) Evidence of the persistence of the discrete population segment 
in an ecological setting that is unique for the taxon. The petitioner 
asserts that YNP is the only area in the lower 48 States where bison 
have existed in the wild state since prehistoric times. This statement 
is consistent with Gates et al. (2005, p. 245), and indicates that the 
YNP bison herd may exist in a unique ecological setting within the 
meaning of our DPS Policy.
    The petitioner's assertion that the YNP bison were important to 
Native Americans also is supported by Gates et al. (2005, p. 77) (e.g., 
``The Lamar Valley and the Yellowstone River Valley north to 
Livingstone was an important area for bison and Native peoples 
throughout the Holocene.''). We agree with the petitioner that the YNP 
bison herd has substantial cultural and historical value. However, the 
significance criteria in our DPS Policy are based on biological factors 
identified in the Act that show that the population is significant to 
the taxon, and not on human cultural or historical significance. 
Therefore, we did not evaluate cultural and historical significance in 
our DPS analysis, but rather relied solely on the scientific criteria 
in the DPS Policy.
    The petitioner asserts that the YNP is significant because of its 
``quasi-migratory behavior.'' Gates et al. (2005, p. 160) concludes 
that YNP is a forage-limited system, and that, ``Bison move beyond park 
boundaries in winter in response to forage limitation caused by 
interactions between population density, variable forage production 
(driven by spring/early summer precipitation), snow conditions, and 
herbage removal primarily by bison and elk.'' Winter movement of large 
herbivores, such as bison and elk, in search of forage is normal 
behavior. The fact that bison and elk range outside the Park is not 
unusual. Based on this information, we would not consider the YNP bison 
herd movements to winter range outside the Park boundary as a unique 
behavior within the meaning of our DPS Policy.
    (2) Evidence that loss of the population segment would result in a 
significant gap in the range of the taxon. The petition alleges that 
the YNP bison herd is the only remaining wild, unfenced bison herd. As 
discussed under ``Biology and Distribution,'' there are 3 other Federal 
bison herds that show no evidence of introgression with domestic 
cattle, based on sampling done to date. Because of the limited number 
and extent of bison herds that show no evidence of introgression with 
domestic cattle, we find that loss of the YNP

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bison herd might result in a significant gap in the current range of 
the taxon.
    (3) Evidence that the population segment represents the only 
surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historical range. The 
petition provides no specific information to indicate that the YNP 
bison herd would meet this criterion. As noted above, Gates et al. 
(2005, p. 245) indicate that YNP is the only area in the lower 48 
States where bison have existed in a wild state since prehistoric 
times. Bison originally ranged across western North America; because 
numerous herds have been reintroduced in the historic range, we have 
determined that the YNP herd is not the only surviving natural 
occurrence within its range. Additionally, the species is not more 
abundant elsewhere outside its historic range.
    (4) Evidence that the discrete population segment differs markedly 
from other populations of the species in its genetic characteristics. 
The petition alleges that the YNP bison herd may be a unique hybrid of 
the wood and plains bison. No citations are provided, but this 
conclusion was stated in Meagher (1973, pp. 14-16), who considered the 
``mountain'' bison a separate species. This controversy has since been 
resolved, and YNP staff now considers the remnant population, as well 
as the introduced bison, as being of plains bison origin (Boyd 2003, 
pp. 182-183; Wallen 2006).
    Additional information in our files compiled after this petition 
was submitted indicates that the YNP bison herd is one of three Federal 
herds that do not display genetic introgression with cattle. 
Maintenance of genetic diversity is an important long-term goal for 
management of species populations. Halbert (2003, p. 94), concluded her 
study by stating: ``In conclusion, this study has assessed levels of 
domestic cattle introgression in 10 federal bison populations and 
identified at least 2 populations, Wind Cave and YNP, which at this 
time do not have any evidence of domestic cattle introgression and also 
have high levels of unique genetic variation in relation to other 
federal populations. As such, these populations should be given 
conservation priority * * *'' Thus, we conclude that the YNP bison herd 
satisfies this genetic criterion of significance under the DPS Policy.

DPS Determination

    The Grand Teton National Park/National Elk Refuge bison herd is 
separate from the YNP herd (Gates et al. 2005, p. 93), and there are 
less than a dozen other unconfined bison herds in the entire lower 48 
States (Gates et al. 2005, p. 2). Therefore, the YNP herd is discrete 
from other members of the taxon. Recent genetic research confirms that 
the YNP bison herd is significant because of a lack of nuclear domestic 
cattle introgression. Although 3 other Federal herds exhibit this 
characteristic, the YNP bison are the only remnant population that has 
remained in a wild state since prehistoric times and, therefore, is 
important to the management of bison genetic diversity. Halbert (2003, 
pp. 44-45) found only four Federal herds that were sufficiently unique 
to contribute significantly to overall bison genetic diversity.
    On the basis of the preceding discussion, we believe that there is 
substantial information to conclude that the YNP bison herd may be 
discrete and significant within the meaning of our DPS Policy, and 
therefore may constitute a DPS.
    According to our DPS Policy, if a population of a species is found 
to be both discrete and significant, we then evaluate the conservation 
status of the population in relation to the listing factors found in 
section 4(a)(1) of the Act. Our assessment of the conservation status 
of the YNP bison herd, based on the information provided in the 
petition and our files, is provided in the ``Conservation Status'' 
section below.

Conservation Status

    Pursuant to section 4(a) of the Act, we may list a species of a 
taxon on the basis of any one of the following factors: (A) Present or 
threatened destruction, modification, or curtailment of habitat or 
range; (B) overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) inadequacy of 
existing regulatory mechanisms; or (E) other manmade or natural factors 
affecting its continued existence.

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

    The petition asserts that the natural range of the YNP bison herd 
is being curtailed by the interruptions of its members' attempts to 
move out of the Park. The petitioner alleges that in 1996 the herd 
numbered approximately 3,000 head, and that over 1,000 of these bison 
were ``slaughtered'' outside YNP in the winter of 1996-1997, which 
threatened the ``quasi-migratory'' behavior of the herd.
    The petitioner is correct concerning the culling of YNP bison 
outside the Park in the winter of 1997. Since the 1920s, bison that 
venture out of YNP into Montana have been subject to various lethal and 
non-lethal measures to control brucellosis (Gates et al. 2005, p. 83), 
which is a contagious, costly disease of ruminant (cud-chewing) 
animals, such as bison, cattle, and swine. Since 1934, there has been a 
national Cooperative State-Federal Brucellosis Eradication Program, 
because the disease causes decreased milk production, weight loss in 
livestock, loss of young, infertility, and lameness (https://
www.aphis.usda.gov/vs/nahps/brucellosis/). Culling of bison in interior 
YNP for population and brucellosis control ceased in 1968 (Gates et al. 
2005, p. 87).
    However, the population data for the YNP bison herd do not support 
the petitioner's assertion that the 1997 bison mortality in Montana 
threatens the herd or its range. Since the winterkill and lethal 
brucellosis control actions in Montana during 1997, the YNP bison herd 
has continued to grow despite culling for population and brucellosis 
control, and currently numbers approximately 4,500 head (Wallen 2007). 
Additional information on culling is provided under Factor B.
    The petitioner's assertion that hazing and killing of bison outside 
the Park will affect the ``quasi-migratory'' behavior of the herd, and 
will result in a restriction of the range is not supported by 
information available in our files. Bison in YNP attempt to compensate 
for declining per capita food resources by range expansion (Gates et 
al. 2005, p. 131). In other words, bison move out of the Park in the 
winter in search of food, and this pattern has continued since 
implementation of the Joint Bison Management Plan (discussed in greater 
detail under Factor D) in 2000 (Clarke et al. 2005, p. 29). Therefore, 
the available information indicates that control actions have not 
affected the ``quasi-migratory'' ranging behavior of the YNP herd.

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

    As mentioned under Factor A, the petitioner alleges that in 1996 
the herd numbered approximately 3,000 head, and that over 1,000 of 
these bison were ``slaughtered'' outside YNP in the winter of 1996-
1997. The petition claims that ``Half the herd is now gone due to their 
slaughter.''
    However, as stated under Factor A, the population data for the YNP 
bison herd do no support the contention that half the herd is now gone 
due to lethal

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control. In fact, since the winterkill and lethal brucellosis control 
actions in Montana during 1996-97, the YNP bison herd has continued to 
grow, and currently numbers approximately 4,500 head (Wallen 2006). 
Breeding success has been steady for at least 100 years, in spite of 
culling for population and brucellosis control (Fuller 2003, pp. 21-
28). As part of the Joint Bison Management Plan, variable numbers of 
bison may be removed from the herd to maintain optimal population size 
and for brucellosis control. In addition, the Joint Bison Management 
Plan establishes that when the population drops to 2,300 bison, 
measures to protect bison will be increased. Management mortality would 
cease if the herd drops to 2,100 head. The herd may stabilize at about 
3,500 to 3,800 head, but could fluctuate over time based on the 
severity of winter weather (USDI and USDA 2000, pp. 51-52).

Factor C. Disease or Predation

    The petitioner provides no information on this factor, and we have 
no information in our files to indicate that the current conservation 
status of the YNP bison herd is affected by disease or predation. 
Although brucellosis is endemic to the herd, the disease does not 
appear to be a threat because the population continues to grow at a 
rate of between 5 and 8 percent (Fuller 2006, pp. 21-24). The Joint 
Bison Management Plan provides a detailed set of procedures for 
managing the YNP bison herd in conjunction with the brucellosis control 
program in Montana.
    Gates et al. (2005, p. 51) concluded that predation may become 
increasingly important as reintroduced wolves learn how to kill bison, 
but there is no information in our files to indicate that predation is 
a threat at this time.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

    The petitioner implies that existing regulatory mechanisms are 
inadequate to ensure protection of the YNP bison herd because some 
animals are killed outside the Park. We are assuming that, based on the 
information in our files, the petitioner is referring to lethal control 
of bison in conjunction with Montana's brucellosis control program.
    During the 1990s, a Bison Management Plan for the State of Montana 
and YNP (Joint Bison Management Plan) was developed. A Final 
Environmental Impact Statement and Record of Decision on the plan was 
issued by the Department of the Interior and the Department of 
Agriculture on December 20, 2000 (available at https://
www.planning.nps.gov/document/yellbisonrod%2Epdf). The Joint Bison 
Management Plan provides a detailed set of procedures for managing the 
YNP bison herd in conjunction with the brucellosis control program in 
Montana.
    The Joint Bison Management Plan has a population target of greater 
than 2,100 bison (USDI and USDA 2000, pp. 51-52). The plan contains 
contingency measures to assure that the conservation status of the herd 
remains secure. If exigent circumstances arise during severe winters, 
the agencies agree to temporarily modify elements of the plan to 
mitigate total removal of bison. If the bison population declines to 
2,300 within a single winter, the agencies will meet to evaluate 
modifications to the prevailing management prescriptions that could 
reduce the total management removal of bison from the population (USDI 
and USDA 2000, p. 52). If the bison population declines below 2,100 
within a single winter, the agencies will, on a temporary basis for 
that winter, increase implementation of non-lethal management measures. 
One of the primary goals of the Joint Bison Management Plan is to 
provide for a ``free-ranging bison herd'' (USDI and USDA 2000, p. 6). 
The herd may stabilize at about 3,500 to 3,800 head, but could 
fluctuate over time based on the severity of winter weather (USDI and 
USDA 2000, pp. 51-52). This size range was identified by YNP staff as 
sufficient to protect the long-term status of the herd. The latest 
conservation genetics information indicates that a population in this 
range should be able to sustain the current level of genetic diversity 
indefinitely without the need for introducing immigrants from other 
populations (Wallen 2006).
    The Joint Bison Management Plan Status Review Team recently 
completed an analysis of the adaptive management elements of the plan 
(Clarke et al. 2005, pp. 28-29). With regard to YNP bison population 
abundance, the team found that the abundance of bison has grown 
steadily since the implementation of the Joint Bison Management Plan 
(see Figure 1). The population reached almost 4,900 head in the summer 
of 2005, and now numbers around 4,500. Winter weather conditions have 
been mild to average during the first 5 years, and the population has 
not dropped below 2,300 bison. The late winter population has been 
above the population target and management decision threshold of 3,000 
head in 4 of the 5 years of implementation (Clarke et al. 2005, p. 28). 
Management-related mortality has resulted in greater than 200 bison 
removed during 3 of the 5 winters, but the population continues to 
expand (Clarke et al. 2005, p. 28). Based on this information we concur 
with the Status Review Team that the Joint Bison Management Plan is 
working with regard to successful management of the YNP bison herd.
[GRAPHIC] [TIFF OMITTED] TP15AU07.000


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Factor E. Other Manmade or Natural Factors Affecting Its Continued 
Existence

    The petitioner provided no information on this factor, and we have 
no information in our files to indicate that possible circumstances in 
this category affect the YNP bison herd.

Conclusion of the 5-Factor Analysis

    As required by the Act, we considered the five potential threat 
factors to assess whether there is substantial information to indicate 
that the potential Yellowstone National Park (YNP) bison herd DPS may 
be threatened or endangered throughout all or a significant portion of 
its range. The first step in this assessment is to determine whether 
there is substantial information that the DPS may be threatened or 
endangered throughout all of its range. If this is the case, then we 
make a positive 90-day finding for the DPS in its entirety. If it is 
not the case, we must next consider whether there is substantial 
information that there may be any significant portions of its range 
that are in threatened or endangered.
    On the basis of our review of the petition and other information 
readily available in our files, we have concluded that the petition 
does not present substantial information that listing the potential YNP 
bison herd DPS as threatened or endangered throughout all of its range 
may be warranted. The petition is based primarily on the threat of 
excessive killing of bison that venture outside YNP in order to prevent 
the spread of brucellosis to domestic livestock. However, we found no 
information to indicate that brucellosis control efforts, either 
previous or ongoing, threaten the continued existence of the potential 
YNP bison herd DPS. A large number of bison did die during the severe 
winter of 1996-97 due to the combined effects of natural causes and 
human control efforts, but the herd itself was not threatened by this 
mortality. A Joint Bison Management Plan for the YNP bison herd (USDI 
and USDA 2000), completed and implemented approximately one year after 
the petition was provided to the Service, provides mechanisms to 
address the impacts of brucellosis control actions on the herd while 
maintaining a self-sustaining bison herd in and adjacent to YNP. In 
addition, the population data for the YNP bison herd indicate that, 
since the winterkill and lethal brucellosis control actions in Montana 
during 1996-97, the YNP bison herd has continued to grow despite 
culling for population and brucellosis control, and currently numbers 
approximately 4,500 head.
    Having determined that the potential YNP bison herd DPS does not 
meet the definition of threatened or endangered, we must next consider 
whether there are any significant portions of its range that where the 
herd is danger of extinction or is likely to become endangered in the 
foreseeable future. On March 16, 2007, a formal opinion was issued by 
the Solicitor of the Department of the Interior, ``The Meaning of `In 
Danger of Extinction Throughout All or a Significant Portion of Its 
Range' '' (USDI 2007). We have summarized our interpretation of that 
opinion and the underlying statutory language below. A portion of a 
species' range (in this case, ``species'' refers to the potential YNP 
bison herd DPS) is significant if it is part of the current range of 
the species and is important to the conservation of the species because 
it contributes meaningfully to the representation, resiliency, or 
redundancy of the species. The contribution must be at a level such 
that its loss would result in a decrease in the ability to conserve the 
species.
    The first step in determining whether a species is threatened or 
endangered in a significant portion of its range is to identify any 
portions of the range of the species that warrant further 
consideration. The range of a species can theoretically be divided into 
portions in an infinite number of ways. However, there is no purpose to 
analyzing portions of the range that are not reasonably likely to be 
significant and threatened or endangered. To identify only those 
portions that warrant further consideration, we determine whether there 
is substantial information indicating that (i) the portions may be 
significant and (ii) the species may be in danger of extinction there 
or likely to become so within the foreseeable future. In practice, a 
key part of this analysis is whether the threats are geographically 
concentrated in some way. If the threats to the species are essentially 
uniform throughout its range, no portion is likely to warrant further 
consideration. Moreover, if any concentration of threats applies only 
to portions of the range that are unimportant to the conservation of 
the species, such portions will not warrant further consideration.
    If we identify any portions that warrant further consideration, we 
then determine whether in fact the species is threatened or endangered 
in any significant portion of its range. Depending on the biology of 
the species, its range, and the threats it faces, it may be more 
efficient for the Service to address the significance question first, 
or the status question first. Thus, if the Service determines that a 
portion of the range is not significant, the Service need not determine 
whether the species is threatened or endangered there; if the Service 
determines that the species is not threatened or endangered in a 
portion of its range, the Service need not determine if that portion is 
significant.
    The terms ``resiliency,'' ``redundancy,'' and ``representation'' 
are intended to be indicators of the conservation value of portions of 
the range. Resiliency of a species allows the species to recover from 
periodic disturbance. A species will likely be more resilient if large 
populations exist in high-quality habitat that is distributed 
throughout the range of the species in such a way as to capture the 
environmental variability found within the range of the species. In 
addition, the portion may contribute to resiliency for other reasons--
for instance, it may contain an important concentration of certain 
types of habitat that are necessary for the species to carry out its 
life-history functions, such as breeding, feeding, migration, 
dispersal, or wintering. Redundancy of populations may be needed to 
provide a margin of safety for the species to withstand catastrophic 
events. This does not mean that any portion that provides redundancy is 
a significant portion of the range of a species. The idea is to 
conserve enough areas of the range such that random perturbations in 
the system act on only a few populations. Therefore, each area must be 
examined based on whether that area provides an increment of redundancy 
is important to the conservation of the species. Adequate 
representation ensures that the species' adaptive capabilities are 
conserved. Specifically, the portion should be evaluated to see how it 
contributes to the genetic diversity of the species. The loss of 
genetically based diversity may substantially reduce the ability of the 
species to respond and adapt to future environmental changes. A 
peripheral population may contribute meaningfully to representation if 
there is evidence that it provides genetic diversity due to its 
location on the margin of the species' habitat requirements.
    Applying the process described above for determining whether a 
species is threatened in a significant portion of its range, we next 
addressed whether any portions of the range of the potential YNP bison 
herd DPS warranted further consideration. According to Gates et al. 
(2005), most bison in the YNP herd are confined within Yellowstone 
National Park for all or most of the year. Rut takes

[[Page 45722]]

place within YNP from around mid-July to mid-August (Meagher, 1973) in 
one of three rutting areas--the largest rutting aggregation is in the 
Hayden Valley, the second largest in the eastern Lamar Valley, and a 
small aggregation occurs in small high elevation grasslands on the 
Mirror Plateau and Cache/Calfee Ridge (Gates et al. 2005). Most bison 
remain in YNP during winter, especially in the geothermally-influenced 
central portion of the Park. Calves are born in April-May on the winter 
range (Meagher 1973). For these reasons we have determined that there 
is substantial information that Yellowstone National Park may 
constitute a significant portion of the range for the potential YNP 
bison herd DPS.
    In late winter/early spring, varying numbers of bison may move 
outside the Park's boundaries into Montana near West Yellowstone and 
Gardiner looking for forage. Bison that move outside YNP usually return 
by late spring (YNP, 2007). The proportion of Yellowstone bison that 
move to winter ranges outside YNP varies from 3 to 30 percent per year, 
depending on conditions (YNP, 2007). Bison move beyond Park boundaries 
in late winter in response to forage limitation caused by interactions 
between population density, variable forage production, snow 
conditions, and grazing competition (Gates et al. 2005). The Gardiner 
basin has been considered important winter range for bison since at 
least the 1940s and is an important component of the Northern winter 
range; in contrast, the West Yellowstone area does not have unique 
ecological value as winter range according to Gates et al. (2005). For 
these reasons we believe there is substantial information that the 
Gardiner basin provides resiliency to the herd during harsh winters, 
and, therefore, may constitute a significant portion of the range for 
the potential YNP bison herd DPS.
    On the basis of our review of the petition and other information 
readily available in our files, we have concluded that the petition 
does not present substantial information that the Yellowstone bison 
herd may be threatened or endangered in either of the potentially 
significant portions of the range as outlined in the two previous 
paragraphs. Management of the Yellowstone bison herd is guided by a 
Joint Bison Management Plan for the YNP bison herd (USDI and USDA 
2000). Management of bison within the Park is the responsibility of the 
National Park Service. Culling of bison in interior YNP for population 
and brucellosis management stopped in 1968 (Gates et al. 2005). 
Population data for the YNP bison herd indicate that, since the 
winterkill and lethal brucellosis control actions in Montana during 
1996-97, the YNP bison herd has continued to grow despite culling for 
population and brucellosis control, and currently numbers approximately 
4,500 animals. We therefore conclude that the petition does not present 
substantial information indicating that listing the Yellowstone bison 
herd within YNP may be warranted.
    Outside YNP, management of bison is primarily the responsibility of 
the State of Montana (USDI and USDA 2000). Bison that leave YNP are 
subject to hazing and lethal control as a part of the brucellosis 
control program, but the Joint Bison Management Plan provides 
conservation measures that eliminate the control program as a threat to 
the continued existence of the herd. We therefore conclude that the 
petition does not present substantial information indicating that 
listing the Yellowstone bison herd on the winter range outside YNP may 
be warranted.
    In summary, we have determined that the petition has not presented 
substantial information indicating that the potential YNP bison herd 
DPS may warrant listing as threatened or endangered throughout all or 
any significant portion of its range. Although we will not be 
initiating a status review in response to this petition, we ask the 
public to submit to us any new information that becomes available 
concerning the status of the YNP bison herd or threats to it or its 
habitat at any time. This information will help us monitor and 
encourage the conservation of the species.

References

    A complete list of all references cited herein is available on 
request from the Region 6 Endangered Species Program, U.S. Fish and 
Wildlife Service (see ADDRESSES section).

Author

    The primary author of this document is Chuck Davis, Region 6 
Endangered Species Program, U.S. Fish and Wildlife Service (see 
ADDRESSES section).

Authority

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

    Dated: August 6, 2007.
H. Dale Hall,
Director, U.S. Fish and Wildlife Service.
[FR Doc. E7-16004 Filed 8-14-07; 8:45 am]
BILLING CODE 4310-55-P