[Federal Register: January 28, 2003 (Volume 68, Number 18)]
[Page 4221-4228]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

Endangered and Threatened Wildlife and Plants; 90-Day Finding for 
a Petition to List the Tri-State Area Flock of Trumpeter Swans as 

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.


SUMMARY: We, the Fish and Wildlife Service (Service), announce a 90-day 
finding for a petition to list the Tri-State Area flock of trumpeter 
swans (Cygnus buccinator) as an endangered or threatened species under 
the Endangered Species Act of 1973. We find that the petition does not 
provide substantial information indicating that this flock is a 
Distinct Population Segment (DPS) that may warrant listing. We will not 
be initiating a further status review in response to the petition. 
However, we ask the public to submit to us any new information that 
becomes available concerning the status of or threats to this flock of 
trumpeter swans. This information will help us monitor and manage this 

DATES: The finding announced in this document was made on January 15, 
2003. You may submit new information concerning this species for our 
consideration at any time.

ADDRESSES: Submit information, data, or comments concerning this 
petition to the Assistant Regional Director, Ecological Services, U.S. 
Fish and Wildlife Service, P.O. Box 25486, DFC, Denver, CO 80225-0486. 
The petition, finding, and supporting data are available for public 
inspection, by appointment, during normal business hours, at the above 
address, and on our website at: http://www.r6.fws.gov/birds/trumpeterswan/

FOR FURTHER INFORMATION CONTACT: Chuck Davis, Endangered Species 
Listing Coordinator, at the above address, or by telephone at 303-236-
7400, extension 235, or by email at chuck_davis@fws.gov.


[[Page 4222]]


    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 demonstrate that 
the petitioned action may be warranted. This finding is to be based on 
all information available to us at the time we make the finding. To the 
maximum extent practicable, this finding is to be made within 90 days 
of our receipt of the petition, and the notice of the finding is to be 
published 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)(1)). If we find that substantial information was presented, 
we are required to promptly commence a review of the status of the 
involved species, if one has not already been initiated under our 
internal candidate assessment process.
    In 1989, we were petitioned to list a portion of the trumpeter 
swans in North America (Rocky Mountain Population (RMP), see below) as 
threatened. However, the petition presented information that we deemed 
insufficient to warrant proceeding with a status review (55 FR 17646-
17648; April 16, 1990).
    On August 25, 2000, we received a petition to list the Greater 
Yellowstone (Tri-State) breeding population of the trumpeter swan as 
threatened or endangered. The petitioners, the Biodiversity Legal 
Foundation and Fund for Animals, assert that the Tri-State Area flock 
meets the definition of a DPS, as defined in our policy published 
February 7, 1996 (61 FR 4722), and, therefore, warrants listing because 
of its low population numbers and other threats, including the allowed 
take of trumpeter swans during the hunting seasons in Utah and Nevada.
    On September 22, 2000, we notified the petitioners that our Listing 
Priority Guidance, published in the Federal Register (64 FR 57114) on 
October 22, 1999, designated the processing of new listing petitions as 
a Priority 4 activity (i.e., of lower priority than processing 
emergency listings, processing determinations on proposed species, and 
resolving the status of candidate species). We further informed the 
petitioners that we consider the Tri-State Area trumpeter swan flock as 
a portion of the RMP, which has had an increasing number of swans since 
the 1960s. Therefore, we did not find a compelling reason to consider 
the petition under emergency listing criteria, and no funds were 
available to proceed with an administrative finding at that time.
    On October 25, 2000, the petitioners and the Utah Environmental 
Congress, Margaret Pettis, and Mack P. Bray, filed a formal complaint 
in Federal District Court for the District of Columbia (Fund for 
Animals v. Clark, 00-CV-02558) alleging that we violated the Act by 
failing to publish a 90-day finding for their petition. Plaintiffs also 
allege that the Service violated provisions of the MBTA, the National 
Environmental Policy Act (NEPA), and the Administrative Procedures Act 
by allowing implementation of a limited trumpeter swan hunting season 
in 2000. The case was settled on March 23, 2001, when we agreed to 
reevaluate our compliance with the MBTA and NEPA for the 2002 hunting 
season regulations.
    On February 5, 2001, we received a 60-day notice of intent from 
Meyer and Glitzenstein, legal representatives for the petitioners, 
alleging that we had violated the Act by failing to make a finding as 
to whether the petition to list the Tri-State Area trumpeter swan flock 
presented substantial information indicating that listing may be 
warranted. We responded on April 4, 2001, reiterating that we would not 
be able to begin an evaluation of the petition until the work on the 
higher-priority activities was completed. On September 6, 2001, Meyer 
and Glitzenstein filed another 60-day notice alleging that we violated 
the Act by failing to make a 12-month finding within 1 year of the 
receipt of the trumpeter swan petition.
    On October 3, 2001, plaintiffs were joined by the Humane Society of 
the United States in a new complaint alleging that our reevaluation of 
the swan hunting regulations was not adequate, and that we had violated 
the Act by failing to prepare a 90-day finding on the swan petition 
(Fund for Animals et al. v. Norton, 01-CV-2078 (RMU)).
    On March 5, 2002, plaintiffs filed an amended complaint to include 
the allegation that we had violated the Act by failing to complete a 
12-month finding on the swan petition. The case has been briefed and a 
decision is pending from the court.

Petitioners' Assertions

    Petitioners assert that the Tri-State ``population segment'' of 
trumpeter swans, a group of largely non-migratory swans that breed and 
winter in the Greater Yellowstone area in and around Yellowstone 
National Park in Wyoming, Montana, and Idaho, qualifies as a listable 
entity under the Act in accordance with our DPS policy cited above. The 
petition asserts that the Tri-State segment is geographically and 
biologically distinct from other trumpeter swan groups in North America 
and the United States. The petitioners propose that the segment is 
discrete because it is separated by physical, physiological, 
ecological, behavioral, ``or other factors,'' and is separated by 
approximately 400 miles from any other significant breeding groups of 
this species. Petitioners also assert that the Tri-State Area flock is 
distinct from other swan flocks in Canada by reason of the 
international boundary and alleged differences in exploitation and 
management of this species between Canada and the United States.
    Petitioners allege that the Tri-State Area flock has lost ``more 
than 30 percent of its adults in the past decades, and is in an 
imperiled situation.'' The petition recommends that we consider 
emergency listing of the petitioned DPS.

Distinct Population Segment Analysis

    Under the Act, we must consider for listing any species, 
subspecies, or, for vertebrates, any DPS of these taxa, if sufficient 
information is present to indicate that such action may be warranted.
    To implement the measures prescribed by the Act and its 
Congressional guidance, we developed policy that addresses the 
recognition of DPSs for potential listing actions (61 FR 4722; February 
17, 1996). The policy allows for more refined application of the Act 
that reflects the biological needs of the taxon being considered and 
avoids the inclusion of entities that do not require its protective 
    The Act's legislative history (Senate Report 96-151, 1st Session) 
indicates that Congress expects the Services (Fish and Wildlife Service 
and National Marine Fisheries Service) to use the DPS designation 
``sparingly and only when the biological evidence indicates that such 
action is warranted'' (emphasis added).
    The background information included with the publication of our 
final DPS policy indicates that any interpretation adopted for DPS 
determination should be consistent with the purposes of the Act (i.e., 
``to provide a means whereby the ecosystems upon which endangered 
species and threatened species depend may be conserved, to provide a 
program for conservation of such endangered species and threatened 
species, and to

[[Page 4223]]

take such steps as may be appropriate to achieve the purposes of the 
treaties and conventions set forth in subsection (a) of this section'' 
(emphasis added).
    Under our DPS policy, we use two elements to assess whether a 
population segment under consideration for listing may be recognized as 
a DPS. The elements are: (1) The population segment's discreteness from 
the remainder of the taxon; and (2) the population segment's 
significance to the taxon to which it belongs. Both elements must be 
present for a segment to qualify as a DPS. When responding to a listing 
petition, we are required to use all information available to us at the 
time we make the finding. If we determine that a population segment 
being considered for listing represents a DPS, then the level of threat 
to the population segment is evaluated based on the five listing 
factors established by the Act to determine if listing it as either 
threatened or endangered is warranted. Those listing factors are: (1) 
The present or threatened destruction, modification, or curtailment of 
habitat or range; (2) overutilization for commercial, recreational, 
scientific, or educational purposes; (3) disease or predation; (4) the 
inadequacy of existing regulatory mechanisms; and, (5) other natural 
and manmade factors affecting its continued existence. Listing is 
warranted if one or more of those threats could lead to the extinction 
of the species throughout all or a significant portion of the range of 
the species in the foreseeable future.
    Discreteness--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, (2) It is 
delimited by international governmental boundaries within which 
differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist that are 
significant with regard to conservation of the taxon.
    The petition asserts that the Tri-State segment of trumpeter swans 
is geographically and biologically distinct from other trumpeter swans 
in North America and the United States. The petitioners propose that 
the segment is discrete because it is separated by physical, 
physiological, ecological, behavioral, ``or other factors,'' and is 
separated by approximately 400 miles from any other significant 
breeding groups of this species. Petitioners also assert that the Tri-
State Area flock is distinct from other swan flocks in Canada because 
of the presence of the international boundary and because of alleged 
differences in exploitation and management of this species between 
Canada and the United States. Below we discuss in detail the conditions 
for which we will consider a population to be discrete under the DPS 
policy as applied to the Tri-State Area flock.

(1) Is the Tri-State Area Flock Markedly Separated From Other 
Populations of the Same Taxon as a Consequence of Physical, 
Physiological, Ecological, or Behavioral Factors?

    Historic range maps indicate that the trumpeter swan had a more 
contiguous distribution than exists today. As the species' range was 
restricted due to overexploitation and habitat loss, remnant groups of 
birds inhabited disjunct breeding areas. Although the exact time at 
which the present degree of separation occurred is unknown, we believe 
that it occurred during the peak of trade in swan skins in the mid- to 
late 1800s. Trumpeter swans have relatively long life spans; birds more 
than 24 years old have been recaptured in the wild (Kennard 1975). 
Hence, relatively few (perhaps 6 or 7) generations of trumpeter swans 
have elapsed since that time. Suzuki et al. (1981) state that only one 
immigrating individual per generation is necessary to maintain genetic 
continuity between spatially segregated groups of individuals within a 
species. Mills and Allendorf (1996) suggest a minimum range of 1 to 10 
individuals per generation is needed to maintain gene flow between 
groups of animals. Limited monitoring studies have documented several 
individuals in non-natal nesting areas (Gale et al. 1987, Dubovsky and 
Cornely 2002) and one mixed-group (i.e., Canadian/Tri-State) pairing 
(Shea and Drewien 1999). Further, the Interior Canada and Tri-State 
birds are spatially segregated only during the nesting season; they are 
sympatric (overlapping in range) during winter, when pairing usually 
occurs (Johnsgard 1978, Gale et al. 1987). For these reasons, we 
conclude it is unlikely that the Tri-State Area flock has become 
genetically distinct from the Interior Canada birds. Even if little or 
no movement of birds between flocks has occurred, there is no evidence 
that a sufficient amount of time has passed since the mid-1800s for 
morphology, behavior, and genetics of Tri-State birds to become 
distinctly different from those of other flocks.
    Recently, the Service, in consultation with the Flyway Councils, 
divided trumpeter swans into three administrative populations on the 
basis of areas in which they nest. These populations are defined 
primarily for management purposes and not in recognition of 
reproductive isolation or genetic differentiation (Trost et al. 2000). 
In fact, one of the populations is derived exclusively from birds and 
eggs translocated from the other two populations.
    The Pacific Coast Population (PCP) is comprised primarily of birds 
that nest in Alaska and winter along the west coast of Canada and the 
United States as far south as Oregon (Figure 1). Observations of a very 
limited number of marked birds from this group suggest that birds 
nesting in Alaska do not often migrate or winter east of British 
Columbia or the Pacific Coast States (Dubovsky and Cornely 2002).
    The RMP is comprised of birds that nest east of the range of the 
PCP to areas just east of the western border of Saskatchewan and points 
south. Most birds in the RMP winter at the confluence of the borders of 
Montana, Idaho, and Wyoming (hereafter termed the ``Tri-State'' Area) 
(Subcommittee on Rocky Mountain Trumpeter Swans 1998).
    The Interior Population (IP) is comprised of birds that nest east 
of the range of the RMP. The IP is the result of extensive restoration 
efforts, and is composed almost exclusively of PCP and RMP birds and 
eggs that were translocated to these eastern areas. Birds from the IP 
tend to winter primarily in areas near to or south of their nesting 
grounds (Dubovsky and Cornely 2002).
    Of all the populations, the status of the RMP has been subject to 
the largest amount of debate over the years. The RMP is comprised 
primarily of two groups of birds: one that nests in Canada and the 
other that nests in the Tri-State Area. The latter group contained only 
about 70 birds in the early 1930s. These were erroneously thought to be 
the only free-ranging trumpeter swans in the world (Banko 1960). The 
birds nested primarily in Yellowstone National Park and the Centennial 
Valley area of Montana, and wintered in those areas and adjacent areas 
in Idaho (Banko 1960).

[[Page 4224]]



[[Page 4225]]

    Our analysis of the trumpeter swan Tri-State segment indicates that 
these birds are derived from a remnant flock that survived the market 
hunting overexploitation of the species that occurred in North America 
prior to the protections of the MBTA in 1918. Some swans found refuge 
in the isolated and protected environs of Yellowstone National Park, 
high-elevation areas that have harsh winters and a short nesting season 
compared to lower elevations. Some people speculate that Tri-State 
swans are specially adapted to this marginal habitat. However, we have 
found no scientific evidence to support such a conclusion. No evidence 
indicates that the birds in this flock were isolated for periods of 
time sufficient for such adaptions to occur. Some have speculated that 
the swans that nested in the Tri-State Area once migrated elsewhere for 
the winter, but we know of no data to verify whether they were 
migratory or not prior to European settlement of the Tri-State Area 
(Gale et al. 1987, Dubovsky and Cornely 2002). Implementation of an 
artificial feeding program beginning in 1935 may have modified the 
swans' natural migratory behavior, but that also is conjecture 
(Dubovsky and Cornely 2002).
    The petition alleges that the Tri-State Area flock is discrete from 
other portions of the North American trumpeter swan population in part 
because the Tri-State birds are separated from other breeding 
populations by approximately 400 miles. The petitioners assert that 
breeding pairs are not formed between the Tri-State birds and other 
swan populations.
    There are no known physical, physiological, or behavioral 
differences between any of the trumpeter swan flocks in North America 
(Gale et al. 1987). Even if most of the Tri-State swans do not migrate 
to nesting grounds in Canada (which available data suggest) (Dubovsky 
and Cornely 2002), this behavior is not evolutionarily significant 
within the meaning of our DPS policy. Numerous flocks of geese and 
swans (including trumpeters) in the United States exhibit nonmigratory 
behavior because sufficient life requisites exist in the flocks' 
habitat throughout the year. Therefore, the fact that the birds in the 
Tri-State Area flock are not known to migrate long distances is not a 
unique behavioral trait within the meaning of the DPS policy.
    The petitioners allege, based on neck-collar observations, that the 
Canadian- and United States-nesting birds are reproductively isolated 
because birds have not been seen nesting on their non-natal nesting 
grounds. However, although many swans have been marked over the years, 
observations of marked swans are of a limited value in establishing the 
reproductive isolation of the Tri-State Area flock. Many observations 
of marked swans were of those that had been trapped and translocated. 
It is not appropriate to use observations of these birds to make 
inferences about natural movements and pairing behavior of free-flying 
wild trumpeter swans. Further, many swans are marked but never seen 
again, or are seen only during the first few years after marking (e.g., 
Gale et al. 1987:286, Shea and Drewien 1999). Given that swans are 
long-lived, much of the neck-collar data may reflect only a small 
fraction of these birds' reproductive lifetime and thus is not 
indicative of all of an individual bird's movement patterns. Trumpeter 
swans also inhabit many remote areas that are not amenable to direct 
observations of the birds. Therefore, it is plausible that some marked 
birds may nest in remote areas that are not their natal nesting 
grounds. Lastly, one observation of a mixed-group (Canadian/Tri-State) 
pairing has been documented (Shea and Drewien 1999); mark-recovery 
information indicates two Tri-State Area nesting birds were sighted in 
Alberta (Dubovsky and Cornely 2002), and two birds marked in Grande 
Prairie summered in the Tri-State Area (Gale et al. 1987). These 
instances suggest that some reproductive intermingling of the two 
flocks may be occurring, that gene flow is possible between the groups, 
and that sampling procedures may simply have been inadequate to detect 
much interchange to date. Therefore, we conclude that current 
information does not support the petitioner's allegations that the Tri-
State Area flock is reproductively isolated.
    Our DPS policy provides that quantitative measures of genetic or 
morphological discontinuity may provide evidence of discreteness. As 
discussed in detail below based on current trumpeter swan genetic 
information, we conclude that available information does not provide 
evidence of genetic discontinuity that would support the contention 
that the Tri-State Area flock is discrete.

(2) Is the Tri-State Area Flock Delimited by International Governmental 
Boundaries Within Which Differences in Control of Exploitation, 
Management of Habitat, Conservation Status, or Regulatory Mechanisms 
Exist That Are Significant With Regard to Conservation of the Taxon?

    Under the DPS policy, we specifically look for differences in 
regulatory mechanisms between nations that are significant in light of 
section 4(a)(1)(D) of the Act (e.g., whether inadequate regulatory 
mechanisms in one nation as compared to another may contribute to 
species endangerment), such that it would be consistent with the 
purposes of the Act to delineate a population based on a non-biological 
element. Simply stated, we look for regulatory differences between 
nations that are relevant to a listing decision and that would warrant 
separating populations of a taxon using international boundaries.
    The petitioners allege that the Tri-State Area flock should be 
considered distinct from other trumpeter swan flocks in North America 
because of a difference in management and exploitation of the species 
in Canada. However, migratory waterfowl are managed under the auspices 
of international treaties, including the Migratory Bird Treaty with 
Canada which the MBTA implements, and highly structured international 
entities, such as the Flyway Councils. The goals of the Pacific Flyway 
Council concerning trumpeter swan management are international in scope 
(i.e., the Council contains representatives from both Canada and the 
United States) and include encouraging growth of the Canadian flocks 
while rebuilding United States breeding flocks of trumpeter swans 
(Subcommittee on Rocky Mountain Trumpeter Swans 1998). Public education 
goals and research needs include the same tasks in both countries. The 
Province of Alberta has supported management actions in the United 
States, including implementation of a general swan season (U.S. 
Department of the Interior 2001).
    With regard to habitat management, the United States and Canada 
protect breeding areas, conduct swan transplants, band or otherwise 
mark birds, and monitor population status. Establishment of annual 
sport-hunting regulations in both countries is completed in accordance 
with the Convention Between the United States and Great Britain (for 
Canada) for the Protection of Migratory Birds (1916 Treaty). Both 
countries also publish draft regulations that are subject to public 
review and comment. Neither country has a sport-hunting season 
specifically for trumpeter swans. Swans in both countries are protected 
by similar regulatory processes. Canada and the United States (Alaska) 
allow subsistence take of swans during the spring and summer. As 
discussed earlier in this document, the United States has established a 
limited quota for allowable take of trumpeter swans as part of the 
package of trumpeter swan conservation measures. All waterfowl hunting

[[Page 4226]]

regulations in both countries are subject to annual review and 
revision. Therefore, we find no significant differences in trumpeter 
swan management between Canada and the United States within the meaning 
of our DPS policy.
    In Canada, the trumpeter swan was listed as a vulnerable species in 
1978 (Mackay 1978), but the species was moved to the not-at-risk 
category after re-examination in 1996 (Committee on the Status of 
Endangered Wildlife in Canada 2002). The species is listed as a 
vulnerable species in Alberta (Government of Alberta 2002), which means 
that without management and protection, the species could become 
threatened or endangered within the province (emphasis added). However, 
management actions to enhance trumpeter swan abundance and distribution 
in Alberta are the same as those in the rest of Canada and the Pacific 
flyway, as discussed above.
    Trumpeter swans and tundra swans are both large white birds with 
black bills; the two are extremely difficult to distinguish from each 
other at a distance. Both species can occur in the same area during 
some parts of the year. Since the 1960s we have sanctioned hunting of 
tundra swans (Cygnus columbianus) under the provisions of the Migratory 
Bird Treaty Act (MBTA). Prior to 1995, season lengths for tundra swans 
were quite long (approximately 100 days); the amount of area open to 
hunting was large (essentially the entire State of Utah and areas of 
high swan use in Nevada and Montana). Illegal harvest of trumpeter 
swans during tundra swan hunting seasons occurred, probably by accident 
resulting from misidentification. The degree of take was unknown 
because no monitoring of species-specific swan harvests was conducted.
    The RMP has been increasing at an average annual rate of 4.6 
percent since 1968. The low rate of expansion of trumpeter swans into 
new wintering areas is believed by managers to limit further 
improvement of the status of the species (Subcommittee on Rocky 
Mountain Trumpeter Swans 1998). The Pacific Flyway's subcommittee on 
Rocky Mountain Trumpeter Swans determined that translocation of 
trumpeter swans to new wintering locations was a possible means of 
expanding the wintering range of the swans. Some of the Subcommittee 
members from States with potentially suitable wintering areas for 
translocated birds would not agree to relocations unless tundra swan 
hunters who mistakenly shot a trumpeter swan during the general swan 
season were relieved of liability under the MBTA (U.S. Department of 
the Interior 2001).
    Therefore, to enhance the potential for trumpeter swan range 
expansion and limit the likely but unknown amount of harvest of 
trumpeter swans, several modifications to swan seasons were implemented 
in 1995. First, the area open to swan hunting was greatly reduced, and 
in Utah (where most swans were harvested) the area was restricted to 
only portions of six counties in the northwest corner of the State. The 
season ending date was changed from late January to early December, 
thus reducing the season length by 40 percent, in order to reduce the 
likelihood of sport-hunting mortality for trumpeter swans that may 
migrate into the hunt areas when more-northerly wetlands in the Tri-
State Area freeze. We included provisions for a limited take (quotas) 
of trumpeter swans in Utah (15 individuals) and Nevada (5 individuals) 
to protect hunters from criminal liability if they accidentally shoot a 
trumpeter swan, because it often is not possible for hunters to 
distinguish the two species from each other in the field. If the quota 
was reached in a particular state, all swan hunting would be closed in 
that State for the remainder of the season. Finally, monitoring of swan 
harvest was intensified to enhance detection of trumpeter swans taken 
during hunts. In 2000, the area open to swan hunting in Utah was 
reduced even further, and the quota was reduced to 10 individuals (U.S. 
Department of the Interior 2001). There is no indication that the 
harvest serves as a threat to the continued health of either the Rocky 
Mountain trumpeter swan population or the Tri-State Area flock (see 
Table 1) and, therefore, the take is not significant to the 
conservation of the taxon within the meaning of section 4(a)(1)(D) of 
the Act.
    Although the available evidence does not demonstrate that the Tri-
State flock is discrete under the DPS policy, this flock could 
potentially be considered to be physically separated to some degree 
from the rest of the RMP during the breeding season. Further, our DPS 
policy does not require absolute reproductive isolation as a 
prerequisite to recognizing a DPS. Therefore, we have taken the further 
step of considering the biological and ecological significance of the 
Tri-State Area flock in light of Congressional guidance that the 
authority to list DPSs be used ``sparingly'' while encouraging the 
conservation of genetic diversity. In carrying out this examination, we 
consider available scientific evidence of the discrete population 
segment's importance to the taxon to which it belongs.
    Significance--Our DPS policy provides several examples of the types 
of information that may demonstrate the significance of a population 
segment to the remainder of its taxon, including: (1) Persistence of 
the discrete population segment in an ecological setting unusual or 
unique for the taxon; (2) evidence that the discrete population segment 
differs markedly from other population segments in its genetic 
characteristics; (3) evidence that the discrete population segment 
represents the only surviving natural occurrence of a taxon that may be 
more abundant elsewhere as an introduced population outside its 
historic range; and (4) evidence that loss of the discrete population 
segment would result in a significant gap in the range of the taxon. 
While significance is not necessarily limited to these examples, we 
began by considering each example with respect to the Tri-State Area 
    (1) Ecological setting--The petitioners allege that the Tri-State 
Area flock is an important remnant population of trumpeter swans in the 
lower 48 States and, therefore, meets the significance criterion of the 
DPS policy. Tri-state swans utilize wetland habitats in the region that 
provide requisite feeding, resting, nesting and brood rearing habitats. 
Trumpeters breed in relatively small, shallow wetlands at a wide range 
of elevations from just above sea-level to montane areas in North 
America. The fact that trumpeter swans breed in suitable wetlands in a 
variety of geographically diverse settings does not suggest that the 
Tri-State Area flock is likely to represent a significant resource in 
terms of the overall welfare of the species. The higher elevation, 
montane wetlands appear to provide more marginal breeding habitat for 
swans because of the shorter nesting and brooding season compared to 
wetlands at lower elevations.
    (2) Genetic characteristics--No evidence exists to indicate that 
the Tri-State swans differ markedly from other trumpeter swans 
    The Tri-State birds exhibit no morphological differences from other 
trumpeter swans in North America (Gale et al. 1987). Several studies 
have been conducted to investigate genetic similarities among different 
groups of trumpeter swans nesting in North America (Barrett and Vyse 
1982, Marsolais and White 1997, Pelizza, unpub. ms.). However, to date 
only one of those studies has been accepted for publication in a peer-
reviewed professional journal. Barrett and Vyse (1982) compared blood 
proteins among

[[Page 4227]]

swans from Alaska (PCP), Red Rock Lakes NWR (birds of the Tri-State 
Area flock of the RMP), and Grande Prairie, Alberta (Canada-nesting 
RMP). All three groups of swans shared a common allele for all loci 
surveyed, and the mean heterozygosity of the three groups was not 
different. However, the Alaskan birds possessed alternate alleles at 
several loci, suggesting that the Alaskan group may differ somewhat 
from the Grande Prairie and Red Rock Lakes NWR birds. The genetic 
distance among the three groups was identical, indicating a close 
genetic relationship among the groups, and led the authors to conclude 
that the groups sampled were ``virtually identical based on the index 
of genetic distance.''
    Marsolais and White (1997) studied Band-Sharing Coefficients (BSCs) 
of birds sampled from the PCP, RMP (both Tri-State- and Grande Prairie-
nesting birds), and the IP (Ontario flock, comprised of translocated 
birds from mixed PP/RMP lineages). They found that the IP and RMP birds 
had much higher BSCs than those of PCP birds, suggesting less genetic 
diversity in the former two groups. They hypothesized that the low 
genetic diversity could have been the result of these groups 
experiencing population ``bottlenecks.'' That is, as the range of the 
trumpeter swan decreased in the 1800s, the few spatially disjunct 
groups that remained established at that time were composed of birds 
with similar genetic traits.
    However, as the petitioners (Biodiversity Legal Foundation et al. 
2000, quoting Marsolais 1994) stipulate, ``the fact that the tristate 
and interior Canadian populations did not have significantly different 
mean BSCs, suggests that the tristate population is not less 
genetically variable than the interior Canadian population.'' Marsolais 
(1994) goes on to state that genetic differences may exist and could be 
detected using other techniques. However, subsequent studies to address 
this latter contention have not been conducted.
    Pelizza (unpub. ms.) studied allele frequencies among birds sampled 
from the PCP, Tri-State-nesting birds, and the High Plains flock of the 
IP. His results indicated that some differences existed between the PCP 
birds and those from the latter two groups, but that birds from the 
Tri-State Area and the High Plains flock were essentially identical. He 
did not collect samples from the Interior Canada flock.
    Thus, although several studies have been conducted, only one has 
examined directly the genetic relationship between the Canadian- and 
United States-nesting segments of the RMP. Although that study 
suggested no differences between the groups, the methods used (starch 
gel electrophoresis) are dated compared to contemporary techniques 
using mitochondrial DNA and microsatellites. Thus, Oyler-McCance and 
Quinn (2001) have initiated a study to better assess potential 
differences among the two groups of birds. This current study should 
document the extent of interchange between the Canadian and Tri-State 
Area flocks of the RMP. The proposed techniques recently have been used 
to distinguish among sage grouse populations (Oyler-McCance et al. 
    On the basis of the foregoing discussion of current trumpeter swan 
genetic information, we conclude that available information does not 
provide evidence of genetic discontinuity within the meaning of our DPS 
    (3) Only surviving natural occurrence--A population segment may be 
significant under the DPS policy if it is the only surviving natural 
occurrence of a taxon that may be more abundant elsewhere as an 
introduced population outside its historic range. This is not the case 
with the Tri-State Area trumpeter swan flock.
    (4) Gap in range--If the Tri-State Area flock were lost, there 
would not be a significant gap in the range of this species because 
extant breeding and wintering trumpeter swans are dispersed across 
North America. The creation of a gap in a species' range can have 
bearing on gene flow and the demographic stability of a species as a 
whole. Further, peripheral populations may have genetic characteristics 
essential to the overall long-term conservation of the species (i.e., 
they may be genetically different than more central populations) 
(Lesica and Allendorf 1995). Thus, the consideration of the species' 
range and the potential for creating a gap in that range can be 
significant to the conservation of a taxon. However, in this case the 
potential loss of the Tri-State Area flock is unlikely to have any such 
effects. Managers have repeatedly established or re-established 
breeding flocks of trumpeter swans in various areas of the United 
States and Canada. Restoration flocks derived from exclusively Tri-
State Area-nesting swans have been established at several locations, 
and the loss of a nesting flock in one area would not affect the 
conservation of the taxon within the meaning of our DPS policy. In 
addition, several restoration flocks were established with swans from 
both the Tri-State Area flock and the Pacific Population. Further, RMP 
swans from Canada winter in the Tri-State Area; thus, trumpeter swans 
would occur in the area for at least a portion of every year, and may 
attempt to pioneer vacant areas (note previously mentioned observations 
of the Interior Canada flock birds in the Tri-State Area during the 
    Our DPS policy identifies these factors as examples of the types of 
information that may demonstrate the significance of a population. 
There may be other considerations we have not explicitly addressed 
here. However, we do not find another basis to support a conclusion 
that the Tri-State Area flock is significant to trumpeter swans in 
North America such that it warrants listing under the Act. In 
particular, these facts indicate the opposite: (1) The Tri-State Area 
flock represents only 1 to 3 percent of all trumpeter swans in North 
America, (2) it has been highly manipulated to the extent that it is 
probably the least ``natural'' of all trumpeter swan flocks, and (3) a 
high percentage of restoration flocks outside the Tri-State Area 
include descendants of Tri-State Area birds that are likely to be 
genetically similar to those in the Tri-State Area. As previously 
mentioned, Congressional guidance states that the authority to list 
DPSs is to be used ``sparingly'' while encouraging the conservation of 
genetic diversity. We considered the available scientific evidence 
regarding the Tri-State Area flock's importance to the taxon to which 
it belongs and conclude that it is not significant.

                                 Table 1.--Incidence of Trumpeter Swan Harvest During Swan Season in the Pacific Flyway
                                                                   Utah              Montana (PF) \1\        Montana (CF) \1\             Nevada
                          Year                              Swans     Trumpeters    Swans     Trumpeters    Swans     Trumpeters    Swans     Trumpeters
                                                           examined    detected    examined    detected    examined    detected    examined    detected
1994....................................................        474            0        219            1         31            0         78            0

[[Page 4228]]

1995....................................................        244            3        110            3         22            0         66            0
                                                                     (1 adult, 2             (juveniles)
1996....................................................        701            7        181            3         32            0        110            1
                                                                      (4 adults,                (adults)                                      (juvenile)
1997....................................................        497            3        217            1         55            2        116            0
                                                                      (2 adults,                 (adult)             (1 adult, 1
                                                                     1 juvenile)                                       juvenile)
1998....................................................        879            1        168            3         47            2        156            0
                                                                      (juvenile)              (2 adults,                (adults)
                                                                                             1 juvenile)
1999....................................................        647            0        153            7         50            2        186            0
                                                                                              (4 adults,                (adults)
2000....................................................        454            1        203            3         57            0         65            0
                                                                         (adult)              (2 adults,
                                                                                             1 juvenile)
2001....................................................        229            0        244            0         64            2         51           0
                                                                                                                     (1 adult, 1
\1\ Most if not all of these swans likely are from the Interior Canada flock.
\2\ In 1996, six of the seven trumpeters detected in Utah's harvest were swans marked and translocated from Idaho and released in Utah as part of a
  research proposal. The other swan was a marked swan that was translocated from Idaho to Oregon 2 years earlier.

Petition Finding

    On the basis of the data in our files, we find that the Tri-State 

Area flock of trumpeter swans does not constitute a DPS in the meaning 
of the Act and, therefore, is not a listable entity. The available 
information does not demonstrate that the flock is discrete, because 
the proposed DPS is not markedly separated from other segments of 
trumpeter swans in North America and is not significant under the DPS 
policy. The petitioners assert that the largely nonmigratory behavior 
exhibited by this group of birds indicates that the segment is distinct 
from other flocks because it is physically separated by several hundred 
miles from other breeding populations. However, current banding and 
marking information, although limited in extent, indicates that there 
is some dispersal of swans from the Yellowstone Ecosystem to other 
parts of the RMP area and vice versa, and that pairings between Tri-
State birds and Canadian birds can be expected to occur. All trumpeter 
swans in the RMP are sympatric during several months (approximate 
November to March) of the year. Pairing of trumpeter swans generally 
occurs during the fall and winter months (Johnsgard 1978, Gale et al. 
1987). Thus, this mixing of birds in winter provides the opportunity 
for such pairings to occur. One interflock pairing has been documented 
(Gale et al. 1987). Current data do not provide evidence that the Tri-
State Area flock is genetically different than other trumpeter swan 
flocks, and no data suggest physical, physiological, ecological, or 
significant behavioral differences between the birds in the Yellowstone 
Ecosystem and the rest of North America.
    The petitioners allege that the trumpeter swans in the lower 48 
States are managed differently than the Canadian birds, but we find 
that essentially no differences in management exist, because both 
countries are party to the Migratory Bird Treaty, coordinate on 
planning and implementation of swan management goals, conduct similar 
management activities, and promote population growth of flocks. Both 
trumpeter and tundra swans are cooperatively managed by Canadian and 
United States Federal agencies, States, and Provinces through 
management plans developed specifically for these species.
    In North America the species has increased from less than 4,000 
birds in 1968 to nearly 24,000 birds in 2000, which represents an 
average annual population growth of 5.9 percent (Dubovsky and Cornely 
2002). The RMP increased from approximately 800 birds in 1968 to more 
than 3,600 birds in 2000 (Caithamer 2001). This RMP average population 
growth rate was 4.8 percent per year. Therefore, we conclude that the 
trumpeter swan is not in need of additional protection beyond the 
current provisions of the MBTA.

References Cited

    A complete list of References Cited is available from the Regional 
Office or our website (see ADDRESSES).


    The primary author of this document is Chuck Davis, Region 6 
Endangered Species Listing Coordinator (see ADDRESSES).


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

    Dated: January 15, 2003.
Marshall P. Jones, Jr.,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 03-1804 Filed 1-27-03; 8:45 am]