DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Final Rule To List the Sierra
Nevada Distinct Population Segment of the California Bighorn Sheep as Endangered
ACTION: Final rule.
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
endangered status pursuant to the Endangered Species Act of 1973, as amended (Act) for the
Sierra Nevada distinct population segment of California bighorn sheep (Ovis canadensis
californiana). This species occupies the Sierra Nevada of California, where it is known
from five disjunct subpopulations along the eastern escarpment of the Sierra Nevada, and
thought to total no more than 125 animals. All five subpopulations are estimated to be
very small and are threatened by mountain lion (Felis concolor) predation, disease,
naturally occurring environmental events, and genetic problems associated with small
population size. We emergency listed this population segment of California bighorn sheep
on April 20, 1999. The emergency listing was effective for 240 days. Immediately upon
publication, this action continues the protection provided by the temporary emergency
listing.
DATES: This final rule is effective on January 3, 2000.
SUPPLEMENTARY INFORMATION:
Background
The bighorn sheep (Ovis canadensis) is a large mammal (family Bovidae) originally
described by Shaw in 1804 (Wilson and Reeder 1993). Several subspecies of bighorn sheep
have been recognized on the basis of geography and differences in skull measurements
(Cowan 1940; Buechner 1960). These subspecies of bighorn sheep, as described in these
early works, include O. c. cremnobates (Peninsular bighorn sheep), O. c. nelsoni (Nelson
bighorn sheep), O. c. mexicana (Mexican bighorn sheep), O. c. weemsi (Weems bighorn
sheep), O. c. californiana (California bighorn sheep), and O. c. canadensis (Rocky
Mountain bighorn sheep). However, recent genetic studies question the validity of some of
these subspecies and suggest a need to re-evaluate overall bighorn sheep taxonomy. For
example, Sierra Nevada bighorn sheep appear to be more closely related to desert bighorn
sheep than the O. c. californiana found in British Columbia (Ramey 1991, 1993).
Regardless, the Sierra Nevada bighorn sheep meets our criteria for consideration as a
distinct vertebrate population segment (as discussed below) and is treated as such in this
final rule.
The historical range of the Sierra Nevada bighorn sheep (Ovis canadensis californiana)
includes the eastern slope of the Sierra Nevada, and, for at least one subpopulation, a
portion of the western slope, from Sonora Pass in Mono County south to Walker Pass in Kern
County, a total distance of about 346 kilometers (km) (215 miles (mi)) (Jones 1950;
Wehauser 1979, 1980). By the turn of the century, about 10 out of 20 subpopulations
survived. The number dropped to five subpopulations at mid-century, and down to two
subpopulations in the 1970s, near Mount Baxter and Mount Williamson in Inyo County
(Wehauser 1979). Currently, five subpopulations of Sierra Nevada bighorn sheep occur,
respectively, at Lee Vining Canyon, Wheeler Crest, Mount Baxter, Mount Williamson, and
Mount Langley in Mono and Inyo Counties, three of which have been reintroduced using sheep
obtained from the Mount Baxter subpopulation from 1979 to 1986 (Wehausen et al. 1987).
The Sierra Nevada bighorn sheep is similar in appearance to other desert associated
bighorn sheep. The species' pelage shows a great deal of color variation, ranging from
almost white to fairly dark brown, with a white rump. Males and females have permanent
horns; the horns are massive and coiled in males, and are smaller and not coiled in
females (Jones 1950; Buechner 1960). As the animals age, their horns become rough and
scarred, and will vary in color from yellowish-brown to dark brown. In comparison to many
other desert bighorn sheep, the horns of the Sierra Nevada bighorn sheep are generally
more divergent as they coil out from the base (Wehausen 1983). Adult male sheep stand up
to 1 meter (m) (3 feet (ft)) tall at the shoulder; males weigh up to 99 kilograms (kg)
(220 pounds (lbs)) and females 63 kg (140 lbs) (Buechner 1960).The current and historical
habitat of the Sierra Nevada bighorn sheep is almost entirely on public land managed by
the U.S. Forest Service (FS), Bureau of Land Management (BLM), and National Park Service
(NPS). The Sierra Nevada mountain range is located along the eastern boundary of
California. Peaks vary in elevation from 1825 to 2425 m (6000 to 8000 ft) in the north, to
over 4300 m (14,000 ft) in the south adjacent to Owens Valley, and then drop rapidly in
elevation in the southern extreme end of the range (Wehausen 1980). Most precipitation, in
the form of snow, occurs from October through April (Wehausen 1980).
Sierra Nevada bighorn sheep inhabit the alpine and subalpine zones during the summer,
using open slopes where the land is rough, rocky, sparsely vegetated and characterized by
steep slopes and canyons (Wehausen 1980; Sierra Nevada Bighorn Sheep Interagency Advisory
Group (Advisory Group) 1997). Most of these sheep live between 3,050 and 4,270 m (10,000
and 14,000 ft) in elevation in summer (John Wehausen, University of California, White
Mountain Research Station, pers. comm. 1999). In winter, they occupy high, windswept
ridges, or migrate to the lower elevation sagebrush-steppe habitat as low as 1,460 m
(4,800 ft) to escape deep winter snows and find more nutritious forage. Bighorn sheep tend
to exhibit a preference for south-facing slopes in the winter (Wehausen 1980). Lambing
areas are on safe precipitous rocky slopes. They prefer open terrain where they are better
able to see predators. For these reasons, forests and thick brush usually are avoided if
possible (J. Wehausen, pers. comm. 1999).
Bighorn sheep are primarily diurnal, and their daily activity shows some predictable
patterns that consists of feeding and resting periods (Jones 1950). Bighorn sheep are
primarily grazers; however, they may browse woody vegetation when it is growing and very
nutritious. They are opportunistic feeders selecting the most nutritious diet from what is
available. Plants consumed include varying mixtures of grasses, browse (shoots, twigs, and
leaves of trees and shrubs), and herbaceous plants, depending on season and location
(Wehausen 1980). In a study of the Mount Baxter and Mount Williamson subpopulations,
Wehausen (1980) found that grass, mainly Stipa speciosa (perennial needlegrass), is the
primary diet item in winter. As spring green-up progresses, the bighorn sheep shift from
grass to a more varied browse diet, which includes Ephedra viridis (Mormon tea), Eriogonum
fasciculatum (California buckwheat), and Purshia species (bitterbrush).
Sierra Nevada bighorn sheep are gregarious, with group size and composition varying with
gender and from season to season. Spatial segregation of males and females occurs outside
the mating season, with males more than 2 years old living apart from females and younger
males for most of the year (Jones 1950; Cowan and Geist 1971; Wehausen 1980). Ewes
generally remain in the same band into which they were born (Cowan and Geist 1971). During
the winter, Sierra Nevada bighorn sheep concentrate in those areas suitable for wintering,
preferably Great Basin habitat (sagebrush-steppe) at the very base of the eastern
escarpment. Subpopulation size can number more than 100 sheep, including rams (this was
observed at a time when the population size was larger than it is currently) (J. Wehausen,
pers. comm. 1999). Breeding takes place in the fall, generally in November (Cowan and
Geist 1971). Single births are the norm for North American wild sheep, but twinning is
known to occur (Wehausen 1980). Gestation is about 6 months (Cowan and Geist 1971).
Lambing occurs between late April to early July, with most lambs born in May or June
(Wehausen 1980, 1996). Ewes with newborn lambs live solitarily for a short period before
joining nursery groups that average about six sheep. Ewes and lambs frequently occupy
steep terrain that provides a diversity of slopes and exposures for escape cover. Lambs
are precocious, and within a day or so, climb almost as well as the ewes. Lambs are able
to eat vegetation within 2 weeks of their birth and are weaned between 1 and 7 months of
age. By their second spring, they are independent of their mothers. Female lambs stay with
ewes indefinitely and may attain sexual maturity during the second year of life. Male
lambs, depending upon physical condition, may also attain sexual maturity during the
second year of life (Cowan and Geist 1971). Average lifespan is 9 to 11 years in both
sexes, though some rams are known to have lived to 12 to 14 years old (Cowan and Geist
1971; Wehausen 1980).
Distinct Vertebrate Population Segment
Recent analyses of bighorn sheep genetics and morphometrics (e.g., size and shape of body
parts) suggest reevaluation of the taxonomy of Sierra Nevada bighorn sheep (Ovis
canadensis californiana) is necessary (Ramey 1991, 1993, 1995; Wehausen and Ramey 1993;
Wehausen and Ramey 2000 (in review)). A recent analysis of the taxonomy of bighorn sheep
using morphometrics and genetics failed to support the current taxonomy (Ramey 1993, 1995;
Wehausen and Ramey 1993; Wehausen and Ramey 2000 (in review)). This and other research
(Ramey 1993) supports taxonomic distinction of the Sierra Nevada bighorn sheep relative to
other nearby regions.
The biological evidence supports recognition of Sierra Nevada bighorn sheep as a distinct
vertebrate population segment for purposes of listing, as defined in our February 7, 1996,
Policy Regarding the Recognition of Distinct Vertebrate Population Segments (61 FR 4722).
The definition of ``species'' in section 3(16) of the Act includes ``any distinct
population segment of any species of vertebrate fish or wildlife which interbreeds when
mature.'' For a population to be listed under the Act as a distinct vertebrate population
segment, three elements are considered--1) the discreteness of the population segment in
relation to the remainder of the species to which it belongs; 2) the significance of the
population segment to the species 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).
The distinct population segment (DPS) of bighorn sheep in the Sierra Nevada is discrete in
relation to the remainder of the species as a whole. This DPS is geographically isolated
and separate from other California bighorn sheep populations. There is no mixing of Sierra
Nevada bighorn sheep with other bighorn sheep subspecies. This is supported by an
evaluation of the population's genetic variability and morphometric analysis of skull and
horn variation (Ramey 1993, 1995; Wehausen and Ramey 1993, 1994; Wehausen and Ramey 2000
(in review)). Sierra Nevada bighorn sheep males have particularly wide skulls but small
horns, compared to other subspecies of bighorn sheep (Wehausen and Ramey 2000 (in
review)). Also, Sierra Nevada bighorn sheep have a unique mitochondrial DNA pattern,
different from other bighorn sheep populations (Ramey 1993, 1995). Mitochondrial DNA are
genes that are inherited maternally in animals, and so are useful as genetic markers when
researching population genetic questions (Ramey 1993). Researchers suggest that all other
populations of Ovis canadensis californiana be reassigned to other subspecies, leaving O.
c. californiana (i.e., the subspecies found within the DPS that is the subject of this
rule) only in the central and southern Sierra Nevada (Ramey 1993, 1995; Wehausen and Ramey
1993, 1994; Wehausen and Ramey 2000 (in review)).
The Sierra Nevada bighorn sheep DPS is biologically and ecologically significant to the
species in that it constitutes the only population of California bighorn sheep inhabiting
the Sierra Nevada. This DPS extends from Sonora Pass to Walker Pass, spanning
approximately 346 km (215 mi) of contiguous suitable habitat in the United States. It is
likely that there was gene flow in the past between bighorn sheep populations in the
Sierra Nevada Mountains (Ovis canadensis californiana) and the White-Inyo Mountains (O. c.
nelsoni), which are separated by Owens Valley (Ramey 1993, 1995). Genetic research
indicates, however, that there are differences between the bighorn sheep populations in
the Sierra Nevada and those in the White-Inyo Mountains (Ramey 1991, 1993, 1995). Any
dispersal that occurred between the two mountain ranges was likely by males since female
bighorn sheep have a much lower rate of dispersal, probably due to the females not wanting
to expose themselves or their lambs to predation by crossing the open terrain of Owens
Valley (Ramey 1995). Movement between the populations apparently no longer occurs due to
artificial barriers such as canals, highways, and fences (Jones 1950; Ramey 1993, 1995).
Sierra Nevada bighorn sheep also have different morphological features, and they are
genetically different from other bighorn populations (Ramey 1991, 1993, 1995; Wehausen and
Ramey 1993, 1994; Wehausen and Ramey 2000 (in review)). The loss of Sierra Nevada bighorn
sheep would result in the total extirpation of bighorn sheep from the Sierra Nevada in
California. The loss of Sierra Nevada bighorn sheep in the Sierra Nevada mountain range
would also create a significant gap in bighorn sheep population distribution. The Sierra
Nevada bighorn sheep are the most northern population of bighorn in California, with the
closest population to the north being at Hart Mountain in Oregon (Jinelle, O'Connor,
Lassen National Forest, pers. comm. 1999), and the closest population to the south and
east being the White-Inyo Mountain bighorn populations. The loss of the Sierra Nevada
bighorn sheep would further isolate bighorn sheep populations in Oregon from those in
southern California.
Status and Distribution
Historically, Sierra Nevada bighorn sheep populations occurred along and east of the
Sierra Nevada crest from Sonora Pass (Mono County) south to Walker Pass (Olancha Peak)
(Kern County) (Jones 1950; Wehausen 1979). Sheep apparently occurred wherever appropriate
rocky terrain and winter range existed. With some exceptions, most of the populations
wintered on the east side of the Sierra Nevada and spent summers near the crest (Wehausen
1979).Subpopulations of Sierra Nevada bighorn sheep probably began declining with the
influx of gold miners to the Sierra Nevada in the mid-1880s, and those losses have
continued through the 1900s (Wehausen 1988). By the 1970s, only two subpopulations of
Sierra Nevada bighorn sheep, those near Mount Baxter and Mount Williamson in Inyo County,
are known to have survived (Wehausen 1979). Specific causes for the declines are unknown.
Market hunting may have been a contributing factor as evidenced by menus from historic
mining towns such as Bodie, which included bighorn sheep (Advisory Group 1997). However,
with the introduction of domestic sheep in the 1860s and 1870s, wild sheep are known to
have died in large numbers in several areas from disease contracted from domestic
livestock (Jones 1950; Buechner 1960). Large numbers of domestic sheep were grazed
seasonally in the Owens Valley and Sierra Nevada prior to the turn of the century
(Wehausen 1988), and disease is believed to be the factor most responsible for the
disappearance of bighorn subpopulations in the Sierra Nevada. Jones (1950) suggested that
scabies were responsible for a die-off in the 1870s on the Great Western Divide.
Experiments have confirmed that bacterial pneumonia (teurellaecies), carried normally by
domestic sheep, can be fatal to bighorn sheep (Foreyt and Jessup 1982).In 1971, the Sierra
Nevada bighorn sheep was listed as threatened under the 1970 California Endangered Species
Act (California Department of Fish and Game 1974, as cited by Advisory Group 1997;
California Department of Fish and Game 1999). This classification led to the development
and implementation of a State recovery plan, which has two main goals: (1) create at least
two additional populations numbering at least 100 sheep that could serve as reintroduction
stock in the event of a catastrophic decline in the Mount Baxter subpopulation, and (2)
re-establish the sheep throughout historic ranges in the Sierra Nevada where biologically
and politically feasible (Advisory Group 1997). Intensive field studies began in 1975
which provided accurate census data for the two surviving subpopulations. In 1979,
re-introductions of sheep into historical habitat (also known as the restoration program)
began and was conducted by several Federal and State agencies from 1979 to 1988 (Advisory
Group 1997). By 1979, only 220 sheep were known to exist in the Mount Baxter
subpopulation, and 30 in the Mount Williamson subpopulation (Wehausen 1979). Sheep were
obtained from the Mount Baxter subpopulation and transplanted to three historic locations,
which were Lee Vining Canyon, Wheeler Crest, and Mount Langley (Wehausen 1996; Advisory
Group 1997). Consequently, Sierra Nevada bighorn sheep now occur in five subpopulations in
Mono and Inyo Counties : Lee Vining Canyon, Wheeler Crest, Mount Baxter, Mount Williamson,
and Mount Langley. The Sierra Nevada bighorn sheep population reached a high of about 310
in 1985-86, but subsequent population surveys have documented a declining trend (J.
Wehausen, pers. comm. 1999). Currently, it is estimated that the total Sierra Nevada
bighorn sheep population is 125 animals (J. Wehausen, pers. comm. 1999).
The following table best represents the total Sierra Nevada bighorn sheep population over
various time periods. These totals represent the numbers of sheep emerging from winter in
each of these years, and best documents the status of the population by incorporating
winter mortality, especially of lambs born the previous year. These totals are not
absolute values; numbers have been rounded to the nearest five (J. Wehausen, pers. comm.
1999). The continuing decline of the Sierra Nevada bighorn sheep has been attributed to a
combination of the direct and indirect effects of predation (Wehausen 1996).
Table 1.--Sierra Nevada Bighorn Sheep Population Numbers, by Year (J.
Wehausen, Pers. Comm. 1999)
------------------------------------------------------------------------
Number of
Year populations Total sheep
------------------------------------------------------------------------
1978.......................................... 2 250
1985.......................................... 4 310
1995.......................................... 5 100
1996.......................................... 5 110
1997.......................................... 5 130
1998.......................................... 5 100
1999.......................................... 5 *125
------------------------------------------------------------------------
*Note that the difference in population size between 1998 and 1999 is
based on (1) a small band of bighorn sheep were located in Sand
Mountain (Mount Baxter subpopulation), and (2) approximately 15 lambs
were born to the Wheeler Crest subpopulation in 1999.
Previous Federal Action
In our September 18, 1985, Notice of Review, we designated the Sierra Nevada bighorn sheep
as a category 2 candidate and solicited status information (50 FR 37958). Category 2
candidate species included taxa for which we had information indicating that proposing to
list as endangered or threatened was possibly appropriate, but for which sufficient data
on biological vulnerability and threats were not currently available to support a proposed
rule. Category 1 candidates were those species for which we had sufficient information on
file to support issuance of proposed listing rules. In our January 6, 1989 (54 FR 554),
and November 21, 1991 (56 FR 58804), Notices of Review, we retained the Sierra Nevada
bighorn sheep in category 2. Beginning with our February 28, 1996, Notice of Review (61 FR
235), we discontinued the designation of multiple categories of candidates, and we now
consider only species that meet the definition of former category 1 as candidates for
listing. At that point, the Sierra Nevada bighorn sheep was not identified as a candidate.
On February 12, 1999, we received a petition dated February 9, 1999, from the Friends of
the Inyo, National Parks and Conservation Association, Natural Resources Defense Council,
Sierra Nevada Bighorn Sheep Foundation, and The Wilderness Society, to list the Sierra
Nevada bighorn sheep as endangered throughout its range, with a special request for an
emergency listing under the Act. The petition provided information on the species'
classification and biology, past and present conservation efforts, historic and current
distribution, population trends, and threats facing this species, including small
population effects, disease, predation and habitat curtailment, fire, and inadequacy of
existing regulations.
On April 20, 1999, we published an emergency rule to list the Sierra Nevada distinct
population segment of California bighorn sheep as endangered (64 FR 19300), as well as a
proposed rule (64 FR 19333) to list the species as endangered on that same date.
The processing of this final rule conforms with our listing priority guidance published in
the Federal Register on October 22, 1999 (64 FR 57114). Highest priority is processing
emergency listing rules for any species determined to face a significant and imminent risk
to its well being (Priority 1). Second priority (Priority 2) is processing final
determinations on proposed additions to the Federal lists of endangered and threatened
wildlife and plants. Third priority is processing new proposals to add species to the
lists. The processing of administrative petition findings (petitions filed under section 4
of the Act) is fourth priority. The processing of critical habitat determinations
(prudency and determinability decisions) and proposed and final designations of critical
habitat will no longer be subject to prioritization under the listing priority guidance.
This final rule is a Priority 2 action and is being completed in accordance with the
current listing priority guidance. We have updated this rule to reflect any changes in
information concerning distribution, status, and threats since publication of the proposed
rule.
Summary of Comments and Recommendations
In the April 20, 1999, proposed rule (64 FR 19333), we requested
all interested parties to submit factual reports or information that
might contribute to development of a final rule. A 60-day comment
period closed on June 21, 1999. We contacted appropriate Federal
agencies, State agencies, county and city governments, scientific
organizations, and other interested parties and requested comments. We
published public notices of the proposed rule in the Inyo Register in
Inyo County and Fresno Bee in Fresno County on May 8, 1999, and in the
Mammoth Times in Mono County on May 13, 1999, which invited general
public comment. We did not receive any requests for a public hearing.
We re-opened the comment period on September 30, 1999, at the request
of the Foundation for North American Wild Sheep and to solicit a peer
review of the proposed rule. The comment period ended on October 15,
1999.
During the public comment period, we received written comments from
39 individuals or organizations, with one commenter submitting comments
during both comment periods. All but two commenters supported the
listing of the Sierra Nevada bighorn sheep. One commenter sent a letter
refuting some information presented to us by another commenter. Issues,
and our response to each, are summarized below.
Issue 1: One commenter requested that we recognize a long-term
ecosystem approach for recovery that includes healthy predator/prey
relations.
Our Response: We agree that recovery should be based on restoring,
to the greatest extent possible, the ecosystem such that the natural
dynamics of predator/prey relationships function with minimal or no
human intervention. We recognize this in the rule, and the actual goals
and tasks necessary to achieve recovery of the species will be
discussed in detail in the Sierra Nevada bighorn sheep recovery plan.
Issue 2: Two commenters asked that we designate critical habitat
for the Sierra Nevada bighorn sheep.
Our Response: In the emergency rule, we indicated that designation
of critical habitat was not determinable for the Sierra Nevada bighorn
sheep due to a lack of information sufficient to perform the required
analysis of impacts of the designation. As discussed below in the
critical habitat section, we have re-examined the question of whether
critical habitat is not determinable and have determined that there is
sufficient information to do the required analysis and that designation
of critical habitat for the species is prudent.
As explained in detail in the Final Listing Priority Guidance for
FY 2000 (64 FR 57114), our listing budget is currently insufficient to
allow us to immediately complete all of the listing actions required by
the Act. We will defer critical habitat designation for the Sierra
Nevada bighorn sheep in order to allow us to concentrate our limited
resources on higher priority critical habitat (including court-ordered
designations) and other listing actions, while allowing us to put in
place protections needed for the conservation of the Sierra Nevada
bighorn sheep without further delay.
We plan to employ a priority system for deciding which outstanding
critical habitat designations should be addressed first. We will focus
our efforts on those designations that will provide the most
conservation benefit, taking into consideration the efficacy of
critical habitat designation in addressing the threats to the species,
and the magnitude and immediacy of those
threats. We will develop a proposal to designate critical habitat for
the Sierra Nevada bighorn sheep as soon as feasible, considering our
workload priorities.
Issue 3: Several commenters stated that we should require other
Federal agencies to utilize their authorities to eliminate grazing
permits on Federal land, and initiate formal consultation under section
7 of the Act.
Our Response: Upon emergency listing of the Sierra Nevada bighorn
sheep, we notified all Federal agencies of this listing and their
responsibilities under section 7 of the Act to consult with us on
actions that may affect the Sierra Nevada bighorn sheep. During the
emergency listing period, the FS consulted on their actions for
permitting domestic sheep grazing, conducting prescribed burns to
enhance bighorn sheep winter habitat, as well as removing wreckage from
a crashed airplane in bighorn sheep habitat. With the final listing of
this species, we will continue to expect Federal agencies to comply
with section 7 of the Act and consult with us, and we will work with
these Federal agencies, as well as State agencies, to reduce threats to
the species.
Issue 4: One commenter requested that we clarify our policies and
procedures on deterrence and removal of Sierra Nevada bighorn sheep
predators, and that the final rule should include clear guidelines for
how we will manage predators.
Our Response: In accordance with our Interagency Cooperative Policy
on Recovery Plan Participation and Implementation Under the Endangered
Species Act (July 1, 1994; 59 FR 34272), and our recovery guidelines,
we will develop a recovery plan that is ecosystem-based, and clearly
identify quantifiable recovery criteria and goals, and we will clearly
identify those management actions necessary to achieve recovery of the
species.
Issue 5: One commenter stated that we should conduct studies to
examine biological effects of differential removal of mountain lions on
the Sierra Nevada bighorn sheep.
Our Response: We agree that this should be an important goal of
recovery efforts. In addition to specific management actions, specific
research aimed at better understanding the species and ecosystem (e.g.,
predator/prey relationships, population demography) will be identified
in the recovery plan.
Issue 6: One commenter stated that Federal listing is no longer
warranted because: 1) Assembly Bill (A. B.) 560 was recently signed
into State law providing the California Department of Fish and Game
(CDFG) to remove or take mountain lions that are perceived to be a
threat to the sheep; (2) CDFG was appropriated State funds for the
recovery of the Sierra Nevada bighorn sheep; and (3) Federal agencies
and the Los Angeles Department of Water and Power have demonstrated
good faith efforts at reducing the likelihood of contact between
domestic sheep and the Sierra Nevada bighorn sheep.
Our Response: We disagree. In evaluating the need for listing, we
must look at a variety of factors affecting the species. This DPS of
California bighorn sheep meets the definition of an endangered species
based on several factors, only one of which is mountain lion predation.
We agree that the passage and signing into law of A. B. 560 provides an
additional ability to protect the Sierra Nevada bighorn sheep from
mountain lions, as well as funds for recovery efforts. However, while
this law will reduce the threat from mountain lion predation, it will
not completely eliminate it. In addition, this legislation was enacted
very recently, in September of 1999, and little time has passed to
allow an evaluation of its effectiveness. We also agree that the CDFG
was appropriated funds for the recovery of the species, however, these
funds do not mean that all of the threats to the species have been
removed such that listing is unnecessary. We also agree that the
Federal agencies and Los Angeles Department of Water and Power have
demonstrated good faith efforts at reducing the likelihood of contact
between domestic and wild sheep. However, these efforts have come about
due to the emergency listing and the subsequent requirement that
Federal agencies must consult with us to ensure that their actions do
not jeopardize the continued existence of the species.
Peer Review
In accordance with our July 1, 1994, Interagency Cooperative Policy
for Peer Review in Endangered Species Act Activities (59 FR 34270), we
solicited the expert opinions of three independent specialists
regarding pertinent scientific or commercial data and assumptions
relating to bighorn sheep ecology, predator/prey relationships, and
disease considered in the proposed rule (64 FR 19333). The purpose of
such a review is to ensure that listing decisions are based on
scientifically sound data, assumptions, and analyses, including input
from appropriate experts. All three reviewers sent us a letter during
the public comment period supporting the listing of the Sierra Nevada
bighorn sheep. One of the three provided additional documentation on
disease threats to bighorn sheep from domestic sheep; another provided
conservation and recovery recommendations. Information and suggestions
provided by the reviewers were considered in developing this final
rule, and incorporated where applicable.
Summary of Factors Affecting the Species
After a thorough review and consideration of all information
available, we have determined that the Sierra Nevada bighorn sheep DPS
warrants classification as an endangered species. We followed
procedures found at section 4 of the Act and regulations (50 CFR part
424) issued to implement the listing provisions of the Act. We
determine a species to be endangered or threatened due to one or more
of the five factors described in section 4(a)(1). These factors, and
their application to the Sierra Nevada bighorn sheep DPS (Ovis
canadensis californiana), are as follows:
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
Habitat throughout the historic range of Sierra Nevada bighorn
sheep remains essentially intact; the habitat is neither fragmented nor
degraded. However, by 1900, about half of the Sierra Nevada bighorn
sheep populations were lost, most likely because of the introduction of
diseases by domestic livestock, and illegal hunting (Advisory Group
1997). Beginning in 1979, animals from the Mount Baxter subpopulation
were translocated to reestablish subpopulations in Lee Vining Canyon,
Wheeler Crest, and Mount Langley in Mono and Inyo Counties in order to
re-establish the species in historical habitat (Advisory Group 1997).
Currently, Sierra Nevada bighorn sheep are limited to five
subpopulations. Almost all of the historical and current habitat is
administered by either the FS, BLM, or NPS, though there are some small
parcels of inholdings within the species' range which are owned by the
Los Angeles Department of Water and Power. Also, there are some
patented mining claims in bighorn sheep habitat, but the total acreage
is small.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
During the period of the California gold rush (starting about
1849), hunting to supply food for mining towns may have played a role
in the decline of the population (Wehausen 1988). Besides
being sought as food, Sierra Nevada bighorn sheep were also killed by
sheepmen who considered the species competition for forage with
domestic sheep. The decimation of several wildlife species in the late
1800s prompted California to pass legislation providing protection to
several species including bighorn sheep (Jones 1950; Wehausen 1979).
Commercial and recreational hunting of Sierra Nevada bighorn sheep
is not permitted under State law. There is no evidence that other
commercial, recreational, scientific, or educational activities are
currently a threat. Poaching does not appear to be a problem at this
time.
C. Disease or Predation
Disease is believed to have been the major contributing factor
responsible for the precipitous decline of Sierra Nevada bighorn sheep
starting in the late 1800s (Foreyt and Jessup 1982).
Bighorn sheep are host to a number of internal and external
parasites, including ticks, lice, mites, tapeworms, roundworms, and
lungworms. Most of the time, parasites are present in relatively low
numbers and have little effect on individual sheep and populations
(Cowan and Geist 1971).
Cattle were first introduced into the Sierra Nevada in 1860s but
were replaced with domestic sheep that could graze more extensively
over the rugged terrain (Wehausen et al. 1987; Wehausen 1988). Large
numbers of domestic sheep were grazed seasonally in the Sierra Nevada
prior to the turn of the century, and the domestic sheep would use the
same ranges as the wild sheep, occasionally coming into direct contact
with them. Both domestic sheep and cattle can act as disease
reservoirs. Scabies, most likely contracted from domestic sheep, caused
a major decline of bighorn sheep in California in the 1870s to the
1890s, and caused catastrophic die-offs in other parts of their range
(Buechner 1960). A die-off of bighorn sheep in the 1870s on the Great
Western Divide (Mineral King area of Sequoia National Park) was
attributed to scabies, presumably contracted from domestic sheep (Jones
1950).
Die-offs from pneumonia contracted from domestic sheep is another
important cause of losses. In 1988, a strain of pneumonia, apparently
contracted from domestic sheep, wiped out the reintroduced South Warner
Mountains herd of bighorn sheep (David A. Jessup, CDFG, in litt. 1999).
These bighorn sheep, which included Sierra Nevada bighorn sheep, died
of fibrinopurulent bronchopneumonia, caused by a virulent strain of
Pasteurella species bacteria. Domestic sheep had been observed running
with the bighorn prior to this outbreak (D. Jessup, in litt. 1999).
Native bighorn sheep cannot tolerate strains of respiratory bacteria
such as Pasteurella species, carried normally by domestic sheep, and
close contact with domestic animals results in transmission of disease
and subsequent deaths of the exposed animals (Foreyt and Jessup 1982).
Similar die-offs of bighorn sheep populations have occurred elsewhere,
such as in Lava Beds National Monument, California, and in Gerlach,
Nevada, where it was documented that domestic sheep came into contact
with wild sheep (Foreyt and Jessup 1982; D.A. Jessup, in litt. 1999).
Bighorn sheep can also develop pneumonia independent of contact
with domestic sheep. Lungworms of the genus Protostrongylus are often
an important contributor to the pneumonia disease process in some
situations (J. Wehausen, pers. comm. 1999). Lungworms are carried by an
intermediate host snail, which is ingested by a sheep as it is grazing.
Lungworm often exists in a population without causing a problem.
However, if the sheep are stressed in some way, they may develop
bacterial pneumonia, which is complicated by lungworm infestation.
Bacterial pneumonia is usually a sign of weakness caused by some other
agent such as a virus, parasite, poor nutrition, predation, human
disturbance, or environmental or behavioral stress that lowers the
animal's resistence to disease (Wehausen 1979; Foreyt and Jessup 1982).
Bighorn sheep in the Sierra Nevada carry Protostrongylus species
(lungworms), but the parasite loads have been low, and there has been
no evidence of any clinical signs of disease or disease transmission
(Wehausen 1979; Richard Perloff, Inyo National Forest, pers. comm.
1999).
Currently, domestic sheep grazing allotments are permitted by the
FS in areas adjacent to Sierra Nevada bighorn sheep subpopulations.
Domestic sheep occasionally escape the allotments and wander into
bighorn sheep areas, sometimes coming into direct contact with bighorn
sheep (Advisory Group 1997). For example, in 1995, 22 domestic sheep
that were permitted on FS land wandered away from the main band and
were later found in Yosemite National Park, after crossing through
occupied bighorn sheep habitat (Advisory Group 1997; Bonny Pritchard,
Inyo National Forest, pers. comm. 1999; R. Perloff, pers. comm. 1999).
Other stray domestic sheep, in smaller numbers, have been known to
wander up the road in Lee Vining Canyon into bighorn sheep habitat (B.
Pritchard, pers. comm. 1999). Based on available information, and given
the susceptibility of bighorn sheep to introduced pathogens, disease
will continue to pose a significant and underlying threat to the
survival of Sierra Nevada bighorn sheep until the potential for contact
with domestic sheep is eliminated.
Predators such as coyote (Canis latrans), bobcat (Lynx rufus),
mountain lion, gray fox (Urocyon cinereoargenteus), golden eagle
(Aquila chrysaetos), and free-roaming domestic dogs prey upon bighorn
sheep (Jones 1950; Cowan and Geist 1971). Predation generally has an
insignificant effect except on small populations such as the Sierra
Nevada bighorn sheep. Coyotes are the most abundant large predator
sympatric (occurring in the same area) with bighorn sheep populations
(Bleich 1999), and are known to have killed young Sierra Nevada bighorn
sheep (Vernon Bleich, CDFG, pers. comm. 1999). In the late 1980s,
mountain lion predation of Sierra Nevada bighorn sheep increased
throughout their range (Wehausen 1996). This trend has continued into
the 1990s, as evidenced by Table 1.
Predation by mountain lions probably was a natural occurrence and
part of the natural balance of this ecosystem. From 1907 to 1963, the
State provided a bounty on mountain lions; the State also hired
professional lion hunters for many years. The bounty most likely kept
the mountain lion population reduced such that bighorn sheep predation
was rare and insignificant. Between 1963 and 1968, mountain lions were
managed as a nongame and nonprotected mammal, and take was not
regulated. From 1969 to 1972, lions were re-classified as game animals.
A moratorium on mountain lion hunting began in 1972 and lion numbers
likely increased. In 1986, the species was again classified as a game
animal, but CDFG hunting recommendations were challenged in court in
1987 and 1988 (Tories et al. 1996). In 1990, a State-wide ballot
initiative (Proposition 117) passed into law prohibiting the killing of
mountain lions except if humans, or their pets or livestock are
threatened. Another ballot measure, Proposition 197, which would have
modified current law regarding mountain lion management failed to pass
in 1996, largely because of the public's concern that the change may
allow mountain lion hunting (Tories et al. 1996). With the removal of
the ability to control the mountain lion population, lion predation
became a significant
limiting factor on Sierra Nevada bighorn sheep.
The increased presence of mountain lions appears to have changed
Sierra Nevada bighorn sheep winter habitat use patterns. Wehausen
(1996) looked at mountain lion predation in two bighorn sheep
subpopulations, one in the Granite Mountains of the eastern Mojave
Desert, and the other in the Mount Baxter subpopulation in the Sierra
Nevada. He found that the lions reduced the subpopulation in the
Granite Mountains to eight ewes between 1989 and 1991, and held it at
that level for 3 years, after which lion predation decreased and the
bighorn sheep subpopulation increased at 15 percent per year for 3
years. All the mortality in that subpopulation was attributed to
mountain lion predation. The Mount Baxter bighorn sheep subpopulation
abandoned its winter ranges, presumably due to mountain lion predation.
Forty-nine sheep were killed by lions on their winter range between
1976 and 1988 out of an average subpopulation size of 127 sheep. These
mortalities from mountain lion predation represented 80 percent of all
mortality on the winter range, and 71 percent for all ranges used.
Evidence also indicates that many of the bighorn sheep killed were
prime-aged animals (J. Wehausen, pers. comm. 1999).
The bighorn sheep on Mount Baxter may have moved to higher
elevations to evade lions. By avoiding the lower terrain and
consequently the higher quality forage present during the spring, sheep
emerged from the winter months in poorer condition. Consequences from
the change in habitat use resulted in a decline in the Baxter
subpopulation due to decreased lamb survival, because lambs were born
later and died in higher elevations during the winter. This may have
also been the case with the Lee Vining subpopulation decline; bighorn
sheep may have run out of fat reserves at a time when they should have
been replenishing their reserves with highly nutritious forage from low
elevation winter ranges. We believe that because of the winter habitat
shift by the bighorn sheep, the Mount Baxter subpopulation has declined
significantly. With the large decline of bighorn sheep on Mount Baxter,
the total population of Sierra Nevada bighorn sheep has now dropped
below what existed during implementation of the restoration program
between 1979 and 1988 (Wehausen 1996; Advisory Group 1997), which
transplanted sheep back into historical habitat. In a 1996 survey on
Mount Williamson, there was no evidence of groups of sheep, and this
subpopulation was the last one found using its low-elevation winter
range in 1986. Mountain lion predation may have led to the extirpation
of this subpopulation, one of the last two native subpopulations of
Sierra Nevada bighorn sheep (Wehausen 1996; J. Wehausen, pers. comm.
1999).
In 1998 and 1999, few mountain lions were documented using the
Wheeler Crest subpopulation winter habitat. As a result, this
subpopulation returned to its winter range, and 15 lambs were born to
the subpopulation in 1998 and again in 1999. The Langley subpopulation
continues to avoid its winter habitat, presumably due to the presence
of mountain lions there. As a result, the ewes were in very poor
condition in the spring and had not recovered to good condition by
August 1999. One sheep was documented to have been killed by a mountain
lion in 1999 (J. Wehausen, pers. comm. 1999).
On September 16, 1999, California enacted legislation (Assembly
Bill 560) amending Proposition 117 allowing the CDFG to remove or take
mountain lions that are perceived to be a threat to the survival of any
threatened, endangered or fully protected sheep species (Diana Craig,
FS, in litt. 1999; Office of the Governor 1999). Passage of this bill
will help manage mountain lion predation on Sierra Nevada bighorn
sheep, but likely will not eliminate this threat. The authority of the
State to manage mountain lion predation under this law is limited and
has not yet been fully tested. For example, the law allows the State to
take mountain lions perceived to be an immediate threat to protected
bighorn sheep. However, it is not clear that this authority extends to
removing lions whose presence at lower elevation, winter sheep habitat
precludes normal, seasonal, bighorn sheep migration patterns. The
ability to migrate to these lower elevation areas for winter use is
considered crucial to improving the productivity rate of bighorn sheep
populations.
The Sierra Nevada bighorn sheep restoration program, implemented
between 1979 to 1988 to reintroduce the sheep into historical habitat,
used the Mount Baxter subpopulation as the source of reintroduction
stock. The three reintroduced subpopulations at Lee Vining Canyon,
Wheeler Crest, and Mount Langley all suffered from mountain lion
predation shortly after translocation of sheep (Wehausen 1996). The Lee
Vining Canyon subpopulation lost a number of sheep to mountain lion
predation, threatening the success of the reintroduction effort (Chow
1991, cited by Wehausen (1996)). The subpopulation was supplemented
with additional sheep, and the State removed one mountain lion each
year for 3 years, which helped reverse the decline of this
subpopulation (Bleich et al. 1991 and Chow 1991, cited by Wehausen
(1996)). Also, because domestic sheep are preyed upon by mountain
lions, livestock operators who have a Federal permit to graze their
sheep on FS land can get a depredation permit from the State, and have
the U.S. Department of Agriculture, Wildlife Services, remove the
mountain lion. The Lee Vining Canyon subpopulation occurs in the
general area where domestic sheep are permitted, and has benefitted
from the removal of mountain lions that were preying on domestic sheep
(B. Pritchard, pers. comm. 1999). However, this subpopulation has
continued to decline, and in 1999, only one reproductive ewe remains
(J. Wehausen, pers. comm. 1999).
D. The Inadequacy of Existing Regulatory Mechanisms
In response to a very rapid decline in population numbers, in 1876
the State legislature amended an 1872 law that provided seasonal
protection for elk, deer and pronghorn to include all bighorn sheep.
Two years later, this law was amended, establishing a 4-year moratorium
on the taking of any pronghorn, elk, mountain sheep or female deer. In
1882, this moratorium was extended indefinitely for bighorn sheep
(Wehausen et al. 1987). In 1971, California listed the California
bighorn sheep as ``rare.'' The designation was changed to
``threatened'' in 1984 to standardize the terminology of the amended
California Endangered Species Act (CESA) (Advisory Group 1997). The
California Fish and Game Commission upgraded the species' status to
``endangered'' in 1999 (Mammoth Times 1999; San Francisco Chronicle
1999; CDFG 1999). Pursuant to the California Fish and Game Code and the
CESA, it is unlawful to import or export, take, possess, purchase, or
sell any species or part or product of any species listed as endangered
or threatened. Permits may be authorized for certain scientific,
educational, or management purposes, and to allow take incident to
otherwise lawful activities.
The policy of the State of California is to protect and preserve all native species and
their habitat, such as the Sierra Nevada bighorn sheep, that are threatened by extinction
or are experiencing a significant decline that, if not halted, would lead to a threatened
or endangered designation (California Fish and Game Commission 1999). However, the Sierra
Nevada bighorn sheep occurs mainly on Federal lands administered by the BLM and the FS.
These Federal agencies are responsible for regulating activities on Federal lands that may
adversely affect bighorn sheep. For example, the State alone cannot effectively address
disease transmission from domestic sheep to Sierra Nevada bighorn sheep because the State
does not regulate grazing on Federal lands.
Since the Sierra Nevada bighorn sheep was listed by the State of California in 1971, the
CDFG has undertaken numerous efforts for the conservation of the sheep, including but not
limited to--(1) intensive field studies; (2) reestablishment of three additional
subpopulations in historical habitat; (3) creation, in 1981, of the Sierra Nevada Bighorn
Sheep Interagency Advisory Group, including representatives from Federal, State, and local
resource management agencies, which has produced the Sierra Nevada Bighorn Sheep Recovery
and Conservation Plan (1984) and a Conservation Strategy for Sierra Nevada Bighorn Sheep
(1997); and (4) culling four mountain lions that were taking Sierra Nevada bighorn sheep,
which played a significant role in the efforts to reestablish one subpopulation (Chow
1991, cited by Wehausen (1996)).Mountain lion hunting has not occurred in California since
1972 (Tories et al. 1996). As a result of passage of Proposition 117 in 1990 prohibiting
the hunting or control of mountain lions, the CDFG lost the authority to remove mountain
lions to protect the Sierra Nevada bighorn sheep and secure their survival. However, in
September of 1999, California passed legislation (A. B. 560) allowing the CDFG to take or
remove mountain lions that are a threat to the Sierra Nevada bighorn sheep populations (D.
Craig, in litt. 1999; Office of the Governor 1999). We believe that this law will help
eliminate the threat due to mountain lion predation, but will likely not completely
eliminate it. In addition, this legislation was enacted so recently that little time has
passed to allow us to evaluate its effectiveness as a regulatory mechanism.
Federal agencies have authority to manage the land and activities under their
administration to conserve the bighorn sheep. Federal agencies are taking steps to enhance
habitat through prescribed burning to improve forage and maintain open habitat, and to
retire domestic sheep allotments that run adjacent to bighorn sheep habitat. For example,
the FS burned 263 hectares (ha) (650 acres (ac)) in 1997 in Lee Vining Canyon to reduce
mountain lion hiding cover, and there are plans to do more burns in other areas on FS land
(R. Perloff, pers. comm. 1999). However, in some cases, because of conflicting management
concerns, conservation efforts are not proceeding as quickly as necessary. Although
efforts have been underway for many years, the FS has been unable to eliminate the known
threat of contact between domestic sheep and the Sierra Nevada bighorn sheep by either
eliminating adjacent grazing allotments, or modifying allotments such that a sufficient
buffer zone exists that would prevent contact between wild and domestic sheep.
In 1971, the State, in cooperation with the FS, established a
sanctuary for the Mount Baxter and Mount Williamson subpopulation of
Sierra Nevada bighorn sheep and called it the California Bighorn Sheep
Zoological Area (Zoological Area) (Wehausen 1979; Inyo National Forest
Land Management Plan (LMP) 1988). The FS set aside about 16,564 ha
(41,000 ac) of FS land for these two subpopulations. At the time, many
felt that the species' decline was related to human disturbance. The
sanctuary was designed to regulate human use in some areas (Hicks and
Elder 1979), and reduce domestic sheep/wild sheep interaction by
constructing a fence below the winter range of the Mount Baxter
subpopulation along the FS and BLM boundary (Wehausen 1979). Adjacent
summer range on NPS land was also given a restrictive designation to
reduce human disturbance (Wehausen 1979). The FS continues to manage
the Zoological Area; it encompasses land designated as wilderness and
mountain sheep habitat (LMP 1988; R. Perloff, pers. comm. 1999).
Despite the establishment of the sanctuary, the sheep population
has continued to decline. This decline is most likely due to mountain
lion predation and the abandonment of low elevation winter range
(Wehausen 1996). Also, the sanctuary fence was constructed only at the
mouth of the canyon where the Mount Baxter herd winters, adjacent to a
stock driveway used to drive domestic sheep towards their summer
grazing allotments on Federal land further north (B. Pritchard, pers.
comm. 1999). The fence does not prevent domestic sheep from leaving
their bands while on the grazing allotments and moving into habitat
used by Sierra Nevada bighorn sheep.
E. Other Natural or Manmade Factors Affecting its Continued Existence
The Sierra Nevada bighorn sheep population is critically small with
a total of only 125 sheep known from 5 subpopulations. There is no
known interaction between the separate subpopulations. The Sierra
Nevada bighorn sheep currently is highly vulnerable to extinction from
threats associated with small population size and naturally occuring
events.
Although inbreeding depression has not been demonstrated in the
Sierra Nevada bighorn sheep, the number of sheep occupying all areas is
critically low. The minimum size at which an isolated group of this
species can be expected to maintain itself without the deleterious
effects of inbreeding is not known. Researchers have suggested that a
minimum effective population size of 50 is necessary to avoid short-
term inbreeding depression, and 500 to maintain genetic variability for
long-term adaptation (Franklin 1980). Small populations are extremely
susceptible to chance variation in age and sex ratios or other
population parameters (demographic stochasticity) and genetic problems
(Caughley and Gunn 1996). Small populations suffer higher extinction
probabilities from chance events such as skewed sex ratio of offspring,
(e.g., fewer females being born than males). For example, the Mount
Langley subpopulation has been declining. In 1996-97, out of a
subpopulation of 4 ewes and 10 rams, 5 lambs were born, of which 4 were
female. Although a positive event for this subpopulation, it could have
been devastating if the female:male ratio had been reversed (J.
Wehausen, pers. comm. 1999).
The five subpopulations include a total of nine female demes (i.e.,
local populations). These demes are defined by separate geographic home
range patterns of the females. Three of these demes appear not to use
low elevation winter ranges at all, and they will probably go extinct
as a result (J. Wehausen, pers. comm. 1999). For example, the Black
Mountain deme, consisting of five ewes, was previously part of the Sand
Mountain deme, which also has five ewes and is part of the Mount Baxter
subpopulation. The Black Mountain deme became a separate deme after
winter range abandonment in the late 1980s, and does not appear to know
of the Sand Mountain winter range, which lies considerably north of
their home range. This deme has shown a steady decline in size (J.
Wehausen, pers. comm. 1999).
There are six female demes that may persist, but all are still very
vulnerable to extinction due to small size. With the likely extinction
of some of the existing demes, the remaining demes become all the more
important to the persistence of this distinct population segment, and
each remaining female is critically important to her deme. Individual
mountain lions can do enormous damage to any of these small demes, as can catastrophic
events such as snow avalanches.
We also do not know the current distribution of genetic variation
among all of these subpopulations. Each subpopulation likely has lost
some genetic variability, thereby reducing its ability for long-term
adaptation. The ultimate goal of conserving this DPS must be to
preserve as much of its genetic variation a possible. It is likely that
all or some of the existing demes now contain some variation not
represented in others. Until some measure of the distribution of
genetic variation exists, every deme should be considered a significant
portion of the overall population. Maintenance of genetic variability
requires the preservation of rams in addition to ewes.
Small, isolated groups are also subject to extirpation by naturally
occurring random environmental events (e.g., prolonged or particularly
heavy winters and avalanches). In 1995, for example, a dozen sheep died
in a single avalanche at Wheeler Crest (J. Wehauser, pers. comm. 1999).
Such threats are highly significant because the subpopulations are
small and it is also common in bighorn sheep for all members of one sex
to occur in a single group. During the very heavy winters in the late
1970s and early 1980s, there was no notable mortality in the
subpopulations because they were using low elevation winter ranges (J.
Wehausen, pers. comm. 1999).
Competition for critical winter range resources can occur between
bighorn sheep and elk and/or deer (Cowan and Geist 1971). However,
competition between these species does not appear significant since
deer and bighorn sheep readily mix on winter range, and the habitat
overlap between elk and bighorn sheep is slight (Wehausen 1979).
In addition to disease, mountain lion predation, and naturally
occurring events, other factors may contribute to bighorn sheep
mortality. For example, two subpopulations (Wheeler Crest and Lee
Vining) have ranges adjacent to paved roadways, exposing individuals
from those subpopulations to potential hazards. Bighorn sheep have been
killed by vehicles in Lee Vining Canyon on several occasions (V.
Bleich, pers. comm. 1999).
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by this species in developing this final rule. All five
subpopulations of the Sierra Nevada distinct population of California
bighorn sheep are imperiled by disease, predation, naturally occurring
environmental events, and the continual loss of genetic variation if
the subpopulations remain small. The Sierra Nevada bighorn sheep
population reached a high of about 310 in 1985-86, but subsequent
population surveys have documented a declining trend. Currently, only
about 125 animals exist. The potential for contact with domestic sheep
and the transmission of disease could, by itself, eliminate an entire
deme. Domestic sheep continue to stray into Sierra Nevada bighorn sheep
habitat and come into close proximity to the resident bighorn sheep on
numerous occasions. However, domestic sheep have not come into contact
with bighorn sheep during these events. Vulnerability to demographic
problems must be viewed as a combination of immediate threats of
predation, changed habitat use due to the presence of mountain lions,
the resultant decline of ewe nutrition and lamb survivorship, exposure
to environmental catastrophes, and the transmission of disease from
domestic sheep. Because of the high potential for these threats to
result in the extinction of this bighorn sheep distinct population
segment, it warrants listing as endangered. Immediately upon
publication, this final rule will continue the protection for this DPS
of California bighorn sheep, which began when we emergency listed this
DPS on April 20, 1999.
Critical Habitat
In the emergency rule, we indicated that designation of critical
habitat was not determinable for the Sierra Nevada bighorn sheep due to
a lack of information sufficient to perform the required analysis of
impacts of the designation. We have re-examined the question of whether
critical habitat is not determinable, and have determined that there is
sufficient information to do the required analysis.
In the absence of a finding that critical habitat would increase
threats to a species, if there are any benefits to critical habitat
designation, then a prudent finding is warranted. In the case of this
species, there may be some benefits to designation of critical habitat.
The primary regulatory effect of critical habitat is the section 7
requirement that Federal agencies refrain from taking any action that
destroys or adversely modifies critical habitat (see Available
Conservation Measures section) . While a critical habitat designation
for habitat currently occupied by this species would not likely change
the section 7 consultation outcome, because an action that destroys or
adversely modifies such critical habitat would also be likely to result
in jeopardy to the species, there may be instances where section 7
consultation would be triggered only if critical habitat is designated.
Examples could include unoccupied habitat or occupied habitat that may
become unoccupied in the future. There may also be some educational or
information benefits to designating critical habitat. We find that
critical habitat is prudent for the Sierra Nevada bighorn sheep.
Our Final Listing Priority Guidance for FY 2000 (64 FR 57114)
states that the processing of critical habitat determinations (prudency
and determinability decisions) and proposed or final designations of
critical habitat will no longer be subject to prioritization under the
Listing Priority Guidance. Critical habitat determinations, which were
previously included in final listing rules published in the Federal
Register, may now be processed separately, in which case stand-alone
critical habitat determinations will be published as notices in the
Federal Register. We will undertake critical habitat determinations and
designations during FY 2000 as allowed by our funding allocation for
that year.'' As explained in detail in the Listing Priority guidance,
our listing budget is currently insufficient to allow us to immediately
complete all of the listing actions required by the Act. Deferral of
the critical habitat designation for the Sierra Nevada bighorn sheep
will allow us to concentrate our limited resources on higher priority
critical habitat and other listing actions, while allowing us to put in
place protections needed for the conservation of the Sierra Nevada
bighorn sheep without further delay. However, because we have
successfully reduced, although not eliminated, the backlog of other
listing actions, we anticipate in FY 2000 and beyond giving higher
priority to critical habitat designation, including designations
deferred pursuant to the Listing Priority Guidance, such as the
designation for this species, than we have in recent fiscal years.
We plan to employ a priority system for deciding which outstanding
critical habitat designations should be addressed first. We will focus
our efforts on those designations that will provide the most
conservation benefit, taking into consideration the efficacy of
critical habitat designation in addressing the threats to the species,
and the magnitude and immediacy of those threats. We will develop a
proposal to designate critical habitat for the Sierra Nevada bighorn
sheep as soon as feasible, considering our workload
priorities. For the immediate future, most of Region 1's listing budget
must be directed to complying with numerous court orders and settlement
agreements, as well as due and overdue final listing determinations.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened under the Act include recognition, recovery actions,
requirements for Federal protection, and prohibitions against certain
activities. Recognition through listing encourages and results in
conservation actions by Federal, State, and private agencies, groups
and individuals. The Act provides for possible land acquisition and
cooperation with the States and requires that recovery actions be
carried out for all listed species. The protection required of Federal
agencies and the prohibitions against taking and harm are discussed, in
part, below.
Section 7(a) of the Act, requires Federal agencies to evaluate
their actions with respect to any species that is proposed or listed as
endangered or threatened, and with respect to its critical habitat, if
any is being designated. Regulations implementing this interagency
cooperation provision of the Act are codified at 50 CFR part 402. If a
species is listed, section 7(a)(2) requires Federal agencies to ensure
that activities they authorize, fund, or carry out are not likely to
jeopardize the continued existence of such a species or to destroy or
adversely modify its designated critical habitat. If a Federal agency
action may affect a listed species or its critical habitat, the
responsible Federal agency must enter into formal consultation with us.
Federal agency actions that may require conference and/or consultation
include those within the jurisdiction of the FS, BLM, and NPS.
We believe that protection of the Sierra Nevada bighorn sheep
requires reduction of the threat of mountain lion predation,
particularly during the months of April and May when bighorn sheep
attempt to use low elevation winter ranges to obtain necessary
nutrition after lambing, and ewes and lambs are most vulnerable to
predation. California's recently enacted legislation (A. B. 560)
allowing removal of mountain lions that threaten Sierra Nevada bighorn
sheep will reduce this threat. Removal of mountain lions may not
necessarily involve lethal techniques.
We believe that protection of the Sierra Nevada bighorn sheep also
requires reduction of the threat of disease transmission from domestic
sheep by preventing domestic sheep from coming into contact with
bighorn sheep. We will work with the FS to reduce the threat of disease
transmission by domestic sheep. Reduction of this threat may involve
elimination of grazing allotments adjacent to bighorn sheep habitat, or
modifying allotments to create a sufficient buffer zone that would
prevent contact between domestic sheep and bighorn sheep.
Listing this species would provide for the development of a
recovery plan. Such a plan would bring together both State and Federal
efforts for the conservation of the species. The plan would establish a
framework for agencies to coordinate activities and cooperate with each
other in conservation efforts. The plan would set recovery priorities
and estimate costs of various tasks necessary to accomplish them. It
also would describe site-specific management actions necessary to
achieve conservation and survival of the Sierra Nevada bighorn sheep.
Additionally, pursuant to section 6 of the Act, we would be able to
grant funds to affected states for management actions promoting the
protection and recovery of this species.
The Act and implementing regulations found at 50 CFR 17.21 set
forth a series of general prohibitions and exceptions that apply to all
endangered wildlife. The prohibitions, as codified at 50 CFR 17.21, in
part, make it illegal for any person subject to the jurisdiction of the
United States to take (including harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, collect, or attempt any such conduct),
import or export, transport in interstate or foreign commerce in the
course of commercial activity, or sell or offer for sale in interstate
or foreign commerce any endangered animal species. It is also illegal
to possess, sell, deliver, carry, transport, or ship any such wildlife
that has been taken illegally. Certain exceptions apply to our agents
and State conservation agencies.
Permits may be issued to carry out otherwise prohibited activities
involving endangered wildlife species under certain circumstances.
Regulations governing permits are at 50 CFR 17.22. For endangered
species, such permits are available for scientific purposes, to enhance
the propagation or survival of the species, or for incidental take in
connection with otherwise lawful activities.
It is our policy, published in the Federal Register on July 1, 1994
(59 FR 34272), to identify to the maximum extent practicable at the
time a species is listed those activities that likely would or would
not constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a listing on
proposed and ongoing activities within a species' range. Activities we
believe will likely result in a violation of section 9 include, but are
not limited to:
(1) Unauthorized trapping, capturing, handling or collecting of
Sierra Nevada bighorn sheep. Research activities involving trapping or
capturing of Sierra Nevada bighorn sheep will require a permit under
section 10(a)(1)(A) of the Act.
(2) Failure to confine livestock to authorized grazing allotments
resulting in transmission of disease or habitat destruction.
Activities we believe will not likely result in a violation of
section 9 are:
(1) Possession, delivery, or movement, including interstate
transport and import into or export from the United States, involving
no commercial activity, of dead specimens of Sierra Nevada bighorn
sheep that were collected prior to April 20, 1999, the date of
publication of the emergency listing rule in the Federal Register;
(2) Normal, legal recreational activities in designated campsites
or recreational use areas, and on authorized trails.
Direct your questions regarding any specific activities to our
Ventura Fish and Wildlife Office (see ADDRESSES section). Requests for
copies of the regulations regarding listed wildlife and about
prohibitions and permits may be addressed to the U.S. Fish and Wildlife
Service, Ecological Services, Endangered Species Permits, 911 Northeast
11th Avenue, Portland, Oregon 97232-4181 (telephone 503/231-2063;
facsimile 503/231-6243).
National Environmental Policy Act
We have determined that an environmental assessment or
environmental impact statement, as defined under the National
Environmental Policy Act of 1969, need not be prepared in connection
with regulations adopted pursuant to section 4(a) of the Act. We
published a notice outlining our reasons for this determination in the
Federal Register on October 25, 1983 (48 FR 49244).
Paperwork Reduction Act
This rule does not contain any information collection requirements
for which Office of Management and Budget (OMB) approval under the
Paperwork Reduction Act, 44 U.S.C. 3501 et seq. is required. An
information collection related to the rule pertaining to permits for
endangered and
threatened species has OMB approval and is assigned clearance number
1018-0094. An agency may not conduct or sponsor, and a person is not
required to respond to, a collection of information unless it displays
a currently valid control number. This rule does not alter that
information collection requirement. For additional information
concerning permits and associated requirements for endangered wildlife,
see 50 CFR 17.22.
References Cited
A complete list of references cited in this rule is available upon
request from the Ventura Fish and Wildlife Office of the U.S. Fish and
Wildlife Service (see FOR FURTHER INFORMATION CONTACT section).
Authors. The primary authors of this final rule are Carl Benz,
Ventura Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT
section), and Barbara Behan, Regional Office, 911 N.E. 11th Avenue,
Portland, Oregon 97232 (telephone 503/231-6131).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Regulation Promulgation
Accordingly, we amend part 17, subchapter B of chapter I, title 50
of the Code of Federal Regulations, as follows:
PART 17--[AMENDED]
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.
2. Amend Sec. 17.11(h) by adding the following, in alphabetical
order under MAMMALS, to the List of Endangered and Threatened Wildlife:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
-------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific Name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
* * * * * * *
Mammals
* * * * * * *
Sheep, Sierra Nevada bighorn..... Ovis canadensis U.S.A. (western U.S.A., CA-Sierra E 660E
NA NA
californiana. conterminous Nevada. 675
states), Canada
(southwest),
Mexico (north).
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
(Source: Federal Register, January 3, 2000, slightly condensed)
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