[Federal Register Volume 63, Number 52 (Wednesday, March 18, 1998)]
[Rules and Regulations]
[Pages 13134-13150]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-6998]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AB73
Endangered and Threatened Wildlife and Plants; Endangered Status
for the Peninsular Ranges Population Segment of the Desert Bighorn
Sheep in Southern California
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: The U.S. Fish and Wildlife Service (Service) determines the
distinct vertebrate population segment of bighorn sheep (Ovis
canadensis) (Peninsular bighorn sheep) occupying the Peninsular Ranges
of southern California, to be an endangered species pursuant to the
Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.), as amended
(Act). The Service originally proposed to list the Peninsular bighorn
sheep throughout its range, which extends into Baja California, Mexico.
However, because new information received during the comment periods
indicated listing bighorn sheep populations in Baja California is not
warranted, the final listing determination includes only the Peninsular
bighorn sheep population segment in the United States. The synergistic
effects of disease; low recruitment; habitat loss, degradation, and
fragmentation; non-adaptive behavioral responses associated with
residential and commercial development; and high predation rates
coinciding with low bighorn sheep population numbers threaten the
continued existence of these animals in southern California. This rule
implements Federal protection and recovery provisions of the Act for
the Peninsular bighorn sheep. Critical habitat is not being designated.
DATES: This rule is effective March 18, 1998.
ADDRESSES: The complete file for this rule is available for inspection,
by appointment, during normal business hours at the U.S. Fish and
Wildlife Service, Carlsbad Field Office, 2730 Loker Avenue West,
Carlsbad, California 92008.
FOR FURTHER INFORMATION CONTACT: Arthur Davenport, at the above address
(telephone: 760/431-9440).
Background
The bighorn sheep (Ovis canadensis) is a large mammal (family
Bovidae) originally described by Shaw in 1804
[[Page 13135]]
(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 this early work, 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, as discussed later, recent
genetic studies question the validity of some of these subspecies and
reveal the need to reevaluate bighorn sheep taxonomy. Regardless of the
taxonomy, Peninsular bighorn sheep in southern California meet the
Service's criteria for consideration as a distinct vertebrate
population segment and are treated as such in this final rule.
Bighorn sheep (Ovis canadensis) are found along the Peninsular
Mountain Ranges from the San Jacinto Mountains of southern California
south into the Volcan Tres Virgenes Mountains near Santa Rosalia, Baja
California, Mexico, a total distance of approximately 800 kilometers
(km) (500 miles (mi)). The area occupied by the distinct vertebrate
population segment covered in this final rule coincides with the range
of the currently questioned subspecies O. c. cremnobates in California.
The California Fish and Game Commission listed O. c. cremnobates as
``rare'' in 1971. The designation was changed to ``threatened'' by the
California Department of Fish and Game (CDFG) to conform with
terminology of the amended California Endangered Species Act (CESA).
The Peninsular bighorn sheep is similar in appearance to other
desert associated bighorn sheep. The species' pelage (coat) is pale
brown, and its permanent horns, which become rough and scarred with
age, vary in color from yellowish-brown to dark brown. The horns are
massive and coiled in males; in females, they are smaller and not
coiled. In comparison to other desert bighorn sheep, the Peninsular
bighorn sheep is generally described as having paler coloration and
larger and heavier horns that are moderately divergent at the base
(Cowan 1940).
The habitat still remaining for the Peninsular bighorn sheep in the
United States is managed by the California Department of Parks and
Recreation (CDPR) (46 percent), Bureau of Land Management (BLM) (27
percent), private landowners (24 percent), Bureau of Indian Affairs (1
percent), U.S. Forest Service (USFS) (1 percent), and other State
agencies (1 percent) (BLM 1993).
The Peninsular bighorn sheep occurs on open slopes in hot and dry
desert regions where the land is rough, rocky, sparsely vegetated and
characterized by steep slopes, canyons, and washes. Most of these sheep
live between 91 and 1,219 meters (m) (300 and 4,000 feet (ft)) in
elevation where average annual precipitation is less than 10
centimeters (cm) (4 inches (in)) and daily high temperatures average
104 deg. Fahrenheit in the summer. Caves and other forms of shelter
(e.g., rock outcrops) are used during inclement weather. Lambing areas
are associated with ridge benches or canyon rims adjacent to steep
slopes or escarpments. Alluvial fan areas are also used for breeding
and feeding activities.
From May through October, bighorn sheep are dependent on permanent
sources of water and are more localized in distribution. Bighorn sheep
populations aggregate during this period due to a combination of
breeding activities and diminishing water sources. Summer concentration
areas are associated primarily with dependable water sources, and
ideally provide a diversity of vegetation to meet the forage
requirements of bighorn sheep.
Bighorn sheep species are diurnal. Their daily activity pattern
consists of feeding and resting periods that are not synchronous either
within or between groups, as some sheep will be resting while others
are feeding. Browse is the dominant food of desert-associated bighorn
sheep. Plants consumed may include brittlebrush (Encelia sp.), mountain
mahogony (Cercocarpus sp.), Russian thistle (Salsola sp.), bursage
(Hyptis sp.), mesquite (Proposis sp.), palo verde (Cercidium sp.), and
coffeeberry (Rhamnus sp.). During the dry season, the pulp and fruits
of various cacti are eaten. Native grasses are eaten throughout the
year and are important food, especially near waterholes.
Bighorn sheep species produce only one lamb per year. The gestation
period is about 5 to 6 months (Geist 1971). Lambing occurs between
January and June, with most lambs being born between February and May.
Lactating ewes and young lambs congregate near dependable water sources
in the summer. Ewes and lambs frequently occupy steep terrain that
provides a diversity of slopes and exposures for escape cover and
shelter from excessive heat. Lambs are precocial and within a day or so
climb as well as the ewes. Lambs are able to eat native grass within 2
weeks of their birth and are weaned between 1 and 7 months of age. By
their second spring, bighorn sheep lambs are independent of the ewes
and, depending upon physical condition, may attain sexual maturity
during the second year of life (Cowan and Geist 1971, Geist 1971).
Distinct Vertebrate Population Segment
Recent analyses of bighorn sheep genetics and morphometrics suggest
that the taxonomy of Peninsular bighorn sheep needs to be reevaluated
(Ramey 1991, Whehausen and Ramey 1993, Boyce et al. 1997). A recent
analysis of the taxonomy of bighorn sheep using morphometrics (e.g.,
size and shape of skull components) failed to support the current
taxonomy (Wehausen and Ramey 1993). Ramey (1995) found little genetic
variation among desert bighorn sheep using restriction fragment length
polymorphism (RFLP) analysis.
By contrast, Boyce et al. (1997) found high genetic diversity
within and between populations of desert bighorn sheep. In this study,
microsatelite loci (MS) and major histocompatibility complex (MHC) were
analyzed. It appears that the results of Ramey (1995) and Boyce et al.
(1997) differ because dissimilar molecular markers were analyzed. That
is, the choice of molecular markers (e.g., mtDNA, microsatelites,
allozymes) and analytical techniques (RFLP, DNA sequencing, etc.)
apparently influence both the discriminating power of the techniques
and conclusions relating to the genetic variability of a species.
Ongoing research into the genetic variation of bighorn sheep using
a refined technique of mtDNA analysis (i.e., DNA sequencing) has
resulted in the discovery of significantly higher genetic variation in
mtDNA of the Peninsular bighorn sheep than was found by Ramey (Walter
Boyce, DVM, Ph.D. and Esther Rubin, University of California at Davis,
in litt., 1997). Boyce and Rubin found several matriarchal lines where
Ramey (1995) found only one. The difference in results apparently is a
result of the increased resolution provided by the technique used by
Boyce and Rubin (Walter Boyce, DVM, Ph.D. and Esther Rubin, University
of California at Davis, in litt., 1997). Regardless how the taxonomy
issue is finally resolved, the biological evidence supports recognition
of Peninsular bighorn sheep as a distinct vertebrate population segment
for purposes of listing as defined in the Service's 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
[[Page 13136]]
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 of bighorn sheep in the Peninsular
Ranges is discrete in relation to the remainder of the species as a
whole. This population segment is geographically isolated and separate
from other desert bighorn sheep. This is supported by an evaluation of
the population's genetic variability and metapopulation structure
(Boyce et al. 1997). The genetic distance found to exist between the
Peninsular bighorn sheep and their nearest neighbors at the north end
of the range (i.e., bighorn sheep occupying the Orocopia, Eagle, and
San Gorgonio mountains) was three times greater than that found within
subpopulations of Peninsular bighorn sheep sampled (Boyce et al. 1997).
Genetic distance is a measure of the degree of genetic difference
(divergence) between individuals, populations, or species.
The distinct vertebrate population segment covered in this final
rule extends from the northern San Jacinto Mountains to the
international border between the United States and Mexico. The range of
Peninsular bighorn sheep in Mexico extends southward into the Volcan
Tres Virgenes Mountains, located just north of Santa Rosalia, Baja
California, Mexico, and is not addressed in this rulemaking. In
accordance with distinct vertebrate population segment policy, the
Service may determine a population to be discreet at an international
border where there are significant differences in (1) the control of
exploitation; (2) management of habitat; (3) conservation status, or
(4) regulatory mechanisms (61 FR 4722). In the case of the Peninsular
bighorn sheep, there are significant differences between the United
States and Mexico in regard to the species' conservation status.
Information received from the Mexican Government indicates the
population in Baja California is not likely to be in danger of
extirpation within the foreseeable future because there are
significantly more animals there than occur in the United States
(Felipe Ramirez, Mexico Institute of Ecology, in litt. 1997). Based on
DeForge et al. (1993) there are estimated to be between 780 and 1,170
adult Peninsular bighorn sheep in Baja California, Mexico, north of
Bahia San Luis Gonzaga. In addition to the higher population numbers,
the Mexican Government has initiated a conservation program for bighorn
sheep that should improve the status of these animals. Based on
information received from the Mexican Government, components of the
conservation program include the involvement of the local people in the
establishment of conservation and management units that allow some use
of the bighorn sheep while promoting its conservation and recovery.
Approximately 1,199,175 ha (485,306 ac) have been included in this
program for Peninsular bighorn sheep.
Peninsular bighorn sheep are biologically and ecologically
significant to the species in that they constitute one of the largest
contiguous metapopulations of desert bighorn sheep. The metapopulation
spans approximately 160 km (100 mi) of contiguous suitable habitat in
the United States. The loss of Peninsular bighorn sheep in the United
States would isolate bighorn sheep populations in Mexico, including the
Weems subspecies, from all other bighorn sheep, thereby producing a
significant gap in the range of bighorn sheep. In addition, the
Peninsular bighorn sheep occur in an area that has marked climatic and
vegetational differences as compared to most other areas occupied by
bighorn sheep. The majority of the range of the Peninsular bighorn
sheep is classified as Colorado Desert, a subarea of the Sonoran
Desert. This area experiences significantly different climatic
variation (e.g., timing and/or intensity of rainfall) than the Mojave
or other Sonoran deserts and contains a somewhat different flora
(Monson and Sumner 1990, Hickman 1993). Though rainfall is greater in
the higher mountains (e.g., San Jacintos), rainfall averages less than
13 mm (5 in) and snow is almost unknown in most of this area (Monson
and Sumner 1990). It is important to note that the Peninsular bighorn
sheep do not typically occur above 1,200 m (4,000 ft) in the higher
mountains (Monson and Sumner 1990). This is unusual because bighorn
sheep typically occupy higher elevational habitat that contains sparse
vegetative cover. The low amount of rainfall, high evapotranspiration
rate, and temperature regime in the majority of the Peninsular bighorn
sheep's range is notably different from other North American deserts.
The species' ability to exist under these conditions suggests unique
behavioral and/or physiological adaptations.
Recent information further supports the significance of the
Peninsular bighorn sheep to the overall species. Based on an evaluation
of the population's genetic variability by Boyce et al. (1997) and
Ramey (1995), the Peninsular bighorn sheep contain a large portion of
the total genetic diversity of the species. Based on these initial
studies, there is at least one distinct haplotype (Ramey 1995) and one
unique MS allele (Boyce et al. 1997) that are restricted entirely to
Peninsular bighorn sheep. High genetic diversity indicates a capacity
to adapt to a changing environment.
Status and Distribution
The Peninsular bighorn sheep in the United States declined from an
estimated 1,171 individuals in 1971 to about 450-600 individuals in
1991 (CDFG 1991). Recent population estimates indicate continued
decline, and Peninsular bighorn sheep in the United States now number
approximately 280 (DeForge et al. 1995, J. Deforge, in litt., 1997, E.
Rubin and W. Boyce, in litt., 1996, W. Boyce and E. Rubin, in litt.,
1997). The population of Peninsular bighorn sheep in the United States
is currently divided amongst approximately eight ewe groups.
About 20 Peninsular bighorn sheep are held in captivity at the
Bighorn Institute in Palm Desert, California. The Bighorn Institute, a
private, nonprofit organization, was established in 1982 to initiate a
research program for the Peninsular bighorn sheep. The Living Desert,
an educational and zoo facility also located in Palm Desert,
California, maintains a group of 10 to 12 Peninsular bighorn sheep at
its facility.
The continuing decline of the Peninsular bighorn sheep is
attributed to a combination of factors, including: (1) the effects of
disease (Buechner 1960, DeForge and Scott 1982, DeForge et al. 1982,
Jessup 1985, Wehausen et al. 1987, Elliott et al. 1994); (2) low
recruitment (DeForge et al. 1982, Wehausen et al. 1987, DeForge et al.
1995); (3) habitat loss, degradation, and fragmentation (J. DeForge, in
litt., 1997, David H. Van Cleve, CDPR, in litt., 1997, USFWS, unpub.
info., 1997); (4) and, more recently, high rates of predation
coinciding with low population numbers (W. Boyce and E. Rubin, in litt.
1997).
[[Page 13137]]
Previous Federal Action
On September 18, 1985, the Service designated the Peninsular
bighorn sheep as a category 2 candidate and solicited status
information (50 FR 37958). Category 2 included taxa for which the
Service 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. In the January 6, 1989 (54 FR 554), and
November 21, 1991 (56 FR 58804), Notices of Review, the Peninsular
bighorn sheep was retained in category 2. In 1990, the Service
initiated an internal status review of these animals. This review was
completed in the spring of 1991 resulting in a change from category 2
to category 1 designation. Category 1 were those taxa for which the
Service had sufficient information on biological vulnerability and
threats to support proposals to list them as endangered or threatened.
This change to category 1 was inadvertently omitted from the November
21, 1991, Animal Notice of Review (56 FR 58804).
On July 15, 1991, the Service received a petition from the San
Gorgonio Chapter of the Sierra Club to list the Peninsular bighorn
sheep as an endangered species. The petition requested that the Service
list the Peninsular bighorn sheep throughout its entire range, or, at
least, list the population occurring in the Santa Rosa and San Jacinto
mountains of southern California, through emergency or normal
procedures. The Service used information from the status review and the
July 15, 1991, petition to determine that substantial information
existed indicating that the Peninsular bighorn sheep may be in danger
of extinction throughout all or a significant portion of its range.
This finding was made on December 30, 1991, pursuant to section
4(b)(3)(A) of the Act and was published in the Federal Register on May
8, 1992, as a proposed rule to list the Peninsular bighorn sheep as
endangered (57 FR 19837). The proposed rule constituted the 1-year
finding for the July 15, 1991, petitioned action. The proposed listing
status was reconfirmed in the November 15, 1994 (59 FR 58982), and
February 28, 1996, (61 FR 7596), and September 19, 1997 (62 FR 49398)
Notices of Review. On February 14, 1995, the Sierra Club Legal Defense
Fund (plaintiff) filed suit in Federal District Court for the Eastern
District of California to compel the Secretary of the Interior and the
Director of the Service to make a final determination to list the
Peninsular bighorn sheep as an endangered or threatened species.
On April 10, 1995, Congress enacted a moratorium prohibiting work
on listing actions (Public Law 104-6), thus preventing the Service from
taking final listing action on the Peninsular bighorn sheep. The
moratorium was lifted on April 26, 1996, by means of a Presidential
waiver, at which time limited funding for listing actions was made
available through the Omnibus Appropriations Act (Pub. L. No. 104-134,
100 Stat. 1321, 1996). The Service published guidance for restarting
the listing program on May 16, 1996 (61 FR 24722).
In response to the Sierra Club Legal Defense Fund suit, the
District Court issued a stay order on April 10, 1996. On October 15,
1996, the plaintiff asked the Court to lift the stay and require the
final Peninsular bighorn sheep listing decision within 30 days. On
November 26, the District Court entered an order denying the
plaintiff's request to lift the stay, but certified the issue
underlying that denial for interlocutory appeal. The case is currently
on interlocutory appeal before the Ninth Circuit Court of Appeals.
Due to new information becoming available during the lapse between
the original comment period (November 4, 1992) and lifting of the
listing moratorium, the Service reopened the public comment period on
April 7, 1997, for 30 days (62 FR 16518). That comment period closed
May 7, 1997. Because of additional requests, the Service reopened the
public comment period on June 17, 1997, for an additional 15 days (62
FR 32733), and then again on October 27, 1997, for another 15 days (62
FR 55563).
The processing of this final rule conforms with the Service's final
listing priority guidance as published in the Federal Register on
December 5, 1996 (61 FR 64475) and subsequently extended on October 23,
1997 (62 FR 55268). The guidance clarifies the order in which the
Service will process rulemakings. The guidance calls for giving highest
priority to handling emergency situations (Tier 1), second highest
priority (Tier 2) to resolving the listing status of the outstanding
proposed listings, third priority (Tier 3) to new proposals to add
species to the list of threatened and endangered plants and animals and
fourth priority (Tier 4) to processing critical habitat determinations
and delistings. This final rule constitutes a Tier 2 action. This rule
constitutes the final determination resulting from the listing proposal
and all comments received during the comment periods.
Summary of Comments and Recommendations
In the May 8, 1992, proposed rule (57 FR 19837) and associated
notifications, all interested parties were requested to submit factual
reports or information that might contribute to the development of a
final rule for the Peninsular bighorn sheep. Appropriate State
agencies, county governments, Federal agencies, scientific
organizations, and other interested parties were contacted and
requested to comment. Legal notices were published in the Riverside
Press-Enterprise and the San Diego Union-Tribune on May 26, 1992, and
invited general public comment on the proposal. No public hearings were
conducted.
In compliance with Service policy on information standards under
the Act (59 FR 34270; July 1, 1994), the Service solicited the expert
opinions of three appropriate and independent specialists regarding
pertinent scientific or commercial data and issues relating to the
taxonomy, population models, and supportive biological and ecological
information for the Peninsular bighorn sheep. In addition, their
opinions were solicited on the discreteness and significance of the
Peninsular bighorn sheep. The responses received from two of the
reviewers supported the proposed listing action and provided additional
insight into the discreteness and significance of the population. All
three reviewers commented on the taxonomy of bighorn sheep and the
general need for a reevaluation of this group. The third reviewer did
not comment on the discreteness or significance of the Peninsular
bighorn sheep nor make a recommendation concerning the listing action.
Information and suggestions provided by the reviewers were considered
in developing this final rule, and incorporated where applicable.
During the initial 6-month comment period the Service received a
total of 56 comments, including 14 that were submitted after the
comment period closed. (Multiple comments from the same party on the
same date were regarded as one comment.) Of these, 40 (71 percent)
supported the listing, ten (18 percent) opposed the listing, and six
(11 percent) were non-committal. During this initial period, the BLM
and the Bighorn Institute took a neutral stance on the proposal. The
CDPR, six conservation organizations, four local governments, and 30
other groups or individuals supported listing. The CDFG, the Desert
Bighorn Council, and several property owners opposed the listing.
[[Page 13138]]
During the three subsequent extensions of the public comment
period, the Service received a total of 49 responses (multiple/same
issue comments received from a single party were regarded as one
comment). Of these, 36 (73 percent) supported the listing, ten (20
percent) opposed the listing, and four (8 percent) were non-committal.
During the first comment period extension, the BLM and the Bighorn
Institute recommended listing the Peninsular population as endangered.
The CDPR and one conservation organization reaffirmed their support for
the listing of the Peninsular bighorn sheep as endangered. On May 6,
1997, MCO Properties, Inc. made an untimely request for public hearing.
In lieu of a hearing, the Service extended the public comment period a
second time.
Subsequent to the second public comment period extension, the
Mexican Government expressed an interest in the potential listing of
the Peninsular bighorn sheep. To acquire additional information on the
status, distribution, and management of bighorn sheep in Baja
California, Mexico, the public comment period was reopened on October
27, 1997 (62 FR 55563). During this third and last comment period
extension, the Mexican Government submitted information pertinent to
the listing proposal (F. Ramirez, in litt. 1997). In particular, the
Mexican Government reported on population numbers and the institution
of a new conservation program for bighorn sheep. Due in part to the
implementation of this conservation program, the southern boundary of
the distinct vertebrate population segment was re-delineated at the
United States/Mexico International Border.
The Service reviewed all of the written comments referenced above.
The comments were grouped and are discussed under the following issues.
In addition, all biological and commercial information obtained through
the public comment period have been considered and incorporated, as
appropriate, into the final rule.
Issue 1: Several commenters contended that the subspecific taxonomy
of Ovis canadensis was the subject of scientific debate that should be
resolved before the Service finalizes this action. At a minimum, the
Service should consider a listing of O. c. cremnobates rather than a
population.
Service Response: The Service concurs that the taxonomy of the
Peninsular bighorn sheep is in need of further scientific review.
However, the final listing determination for the Peninsular bighorn
sheep was based on analysis as a distinct vertebrate population
segment. Section 3(16) of the Act defines a species to include ``* * *
any distinct population segment of any species of vertebrate fish or
wildlife which interbreeds when mature.'' To guide decisions to
recognize distinct vertebrate population segments the Service
established policy on February 7, 1996 (61 FR 4722). The recognition of
Peninsular bighorn sheep as a distinct vertebrate population segment is
consistent with this policy and the biological status of this bighorn
sheep group warrants such designation. See further discussion of this
issue under the Distinct Vertebrate Population Segment section of this
rule.
Issue 2: One commenter stated that bighorn sheep in Baja
California, Mexico, were distinct from those occurring in southern
California, and should therefore not be listed.
Service Response: The southern demarcation for the distinct
vertebrate population segment was moved to the United States/Mexico
International Border because a discreteness condition regarding a
political boundary between two countries was satisfied. However, based
on the best available biological information there is no indication
that Peninsular bighorn sheep in Baja California, Mexico, are
biologically distinct from those in California. The commenter did not
provide additional information supporting this statement.
Issue 3: One commenter observed that the proposed rule did not
comply with the policy on recognizing distinct vertebrate population
segments.
Service Response: The proposed rule was published prior to the
publication of the Service's policy on recognizing distinct vertebrate
population segments (61 FR 4722). The final rule, in addressing only
Peninsular bighorn sheep occurring in southern California, satisfies
the policy. A discreteness condition of the policy recognizes the
validity of delimiting population segments ``by international
governmental boundaries within which differences in control of
exploitation, management of habitat, conservation status, or regulatory
mechanisms exist.'' See the section on Distinct Vertebrate Population
Segment and its relation to the Peninsular bighorn sheep for further
discussion of this issue.
Issue 4: Several commenters expressed concern that data from only a
limited portion of the Peninsular Ranges in California (i.e., the Santa
Rosa Mountains) was being used to characterize the overall status of
the Peninsular bighorn sheep. In addition, the commenters stated that
no attempt was made to gather and analyze data for other portions of
this population's range (e.g., Mexico, Anza Borrego State Park).
Service Response: The Service has sought and evaluated all
available information submitted during the public comment periods or
otherwise available to determine this final listing action including
information specifically related to Peninsular bighorn sheep
populations located in areas other than the Santa Rosa Mountains.
Information on threats and impacts to Peninsular bighorn sheep was
obtained from those conducting research specific to this population
segment. In addition, information on threats affecting bighorn sheep
throughout the United States (e.g., see Geist 1971, Krausman and
Leopold 1986) also was used as a reference to evaluate potential
impacts on Peninsular bighorn sheep.
Although data were not available to plot specific population trends
for all portions of the Peninsular bighorn sheep range (such as that in
Mexico) (Alvarez 1976, Sanchez et al. 1988, Monson 1980, DeForge et al.
1993, Lee and Mellink 1996), there is a marked difference in recent and
historic population estimates. Based on these estimates, there appears
to have been a decline in the number of Peninsular bighorn sheep in
Baja California, Mexico. It is not surprising that Peninsular bighorn
sheep have declined in Baja California, Mexico, given the presence of
the same factors identified for the decline in the United States (e.g.,
introduced pathogens). Although there is no empirical evidence that
active epizootics are occurring at this time, the same diseases that
have been implicated in the mortality of Peninsular bighorn sheep in
the Santa Rosa Mountains have been detected in Peninsular bighorn sheep
within Anza Borrego State Park (Clark et al. 1985), and Baja
California, Mexico (J. DeForge, pers. comm., 1997). However, recent
information provided by the Mexican government (F. Ramirez, in litt.
1997), regarding bighorn sheep found on the peninsula of Baja
California, Mexico, supports the position that the Mexican population
is not likely to be in danger of extirpation within the foreseeable
future. Therefore, Peninsular bighorn sheep are not being listed in
Mexico at this time.
Issue 5: Several commenters questioned a decline in the population
numbers of Peninsular bighorn sheep. In addition, two of the commenters
stated the information used in the proposed rule was speculative in
nature. Another commenter observed that the population had remained
stable over the past 7 years and, therefore, it was premature to list
this species.
[[Page 13139]]
Service Response: The Service is required to base listing decisions
on the best available scientific and commercial information available.
Based on this information, the Service concludes that the Peninsular
bighorn sheep has undergone a significant decline over much of its
range since 1971 and there is a danger of extinction of this distinct
population segment. See sections on Status and Distribution and Summary
of Factors Affecting the Species for further discussion of this issue.
Issue 6: One commenter claimed that inadequate surveys have been
conducted for Peninsular bighorn sheep in Baja California, Mexico.
Service Response: The Service agrees that, even under optimum
conditions, it is difficult to detect each individual animal in a
population during a survey. However, the survey methodology used by
DeForge et al. (1993) (i.e., the use of a helicopter) is an accepted
reliable method for censusing bighorn sheep populations.
Issue 7: One commenter expressed concern regarding the use of
single-year data for sheep recruitment rates. The commenter stated that
this use was not statistically valid or indicative of long-term trends
and argued that high adult survivorship combined with pulses of good
recruitment can counter a year of poor recruitment and allow the
bighorn sheep to thrive. The commenter further suggested that data from
Anza Borrego Desert State Park did not suggest clear and consistent
declines in recruitment.
Service Response: The Service concurs with the general concerns of
the commenter regarding the use of single year data versus long-term
data in determining population trends. Single-year data were used as an
example, in the proposed rule, of the potential effects of introduced
disease on Peninsular bighorn sheep. Moreover, the example of low
recruitment was also used for purposes of clarification. There is
substantial information to support the conclusion that poor recruitment
has been one of several factors contributing to the species' decline
since at least 1977 (DeForge and Scott 1982, DeForge et al. 1982,
Wehausen et al. 1987, Weaver 1989, Elliott et al. 1994, DeForge et al.
1995). As for the status of the Peninsular bighorn sheep, the
population in the United States has declined from an estimated 1,171
individuals in 1971 to approximately 280 in 1997 (CDFG 1991, E. Rubin
and W. Boyce, in litt. 1996; W. Boyce and E. Rubin, in litt. 1997). The
overall precipitous decline is evident from years of data from
representative portions of the range of the Peninsular bighorn sheep,
(Wehausen et al. 1987, Sanchez et al. 1988, Weaver 1989, CDFG 1991,
DeForge et al. 1995, Rubin et al. 1997).
Issue 8: One commenter questioned the validity of portions of the
Service's analysis under Factor E (natural or manmade threats) in the
proposed rule. The commenter additionally stated that the relative
importance of population size, recruitment, and inbreeding in
influencing the species' status was diminished because the Service did
not take the metapopulation structure of the population into
consideration. The commenter went on to contend the factors acting on
small populations that Berger (1990) investigated were not necessarily
limiting the Peninsular bighorn sheep and that his conclusions were
speculative in nature. Another commenter questioned the scientific
validity of Berger's study, because of issues of scale, and submitted a
draft copy of a paper in support of their position.
Service Response: Although the metapopulation structure of the
Peninsular bighorn sheep was not specifically mentioned in the proposed
rule, the importance of maintaining connectivity within the range was
stressed. In this regard, the potential impacts of isolation (e.g.,
inbreeding) were discussed.
The Service agrees that the factors affecting the populations
Berger (1990) studied are not necessarily the same factors affecting
the Peninsular bighorn sheep. However, the Service did not state the
factors were the same in the proposed rule, but, referenced the
conclusion of Berger (1990) that populations containing less than 50
bighorn sheep became extinct within 50 years. Again, the discussion on
this issue in the proposed rule focused on the potential problems of
isolation. Regardless of the metapopulation structure of Peninsular
bighorn sheep, isolation compromises long-term viability. The Service
finds no basis to support the statement that Berger's (1990) results
were speculative. Berger's (1990) results appear to have been based on
observed (reported) population numbers of several populations of
bighorn sheep over an extended period of time. The Service concurs that
the scale of a study can affect the results and ensuing
interpretations. However, the issues facing the Peninsular bighorn
sheep include fragmentation of habitat and the isolation of ewe groups.
It is well known that small isolated groups are subject to a variety of
genetic problems (Lacy 1997).
Issue 9: One commenter recommended the Service address the
introduction and spread of disease due to equestrian use in Peninsular
bighorn sheep habitat.
Service Response: The Service is unaware of any data that support
the notion that disease transmission occurs between horses and bighorn
sheep. If such information becomes available, this issue will be taken
into consideration during the development and implementation of a
recovery plan.
Issue 10: A commenter indicated the Service generally described the
habitat of the Peninsular bighorn sheep in the proposed rule but did
not specifically mention the habitat conditions that exist in the Santa
Rosa Mountains or any other Peninsular Range. Furthermore, without this
information, no specific management strategies can be formulated to
protect the species.
Service Response: The Service agrees that specific management
strategies will have to be based on more detailed ecological data. The
CDFG has been sponsoring studies that will generate data needed to
determine conservation requirements for the survival and recovery of
the Peninsular bighorn sheep. The draft Peninsular Ranges Coordinated
Bighorn Sheep Metapopulation Management Plan (BLM et al. 1993)
describes the Peninsular Ranges' ecosystems and delineates Peninsular
bighorn sheep historic, core, lambing, and movement habitat. These data
will be used to develop conservation and recovery strategies.
Issue 11: One commenter pointed out that neither burros nor
javelina (collared peccary) occur in the California Peninsular Ranges.
Therefore, these species could not compete with the Peninsular bighorn
sheep for food.
Service Response: The Service concurs. Javelina (collared peccary)
and burros were mentioned in the proposed rule in an opening background
paragraph describing potential competitors of bighorn sheep. The
Service did not intend to suggest that javelina specifically competed
with Peninsular bighorn sheep. Although not an issue for Peninsular
bighorn sheep in the United States, burros have been documented in
bighorn sheep habitat in Baja California, Mexico (DeForge et al.,
1993).
Issue 12: One commenter stated that the depleted status of
Peninsular bighorn sheep was due more to mountain lion predation,
conflicts with autos, and low population numbers than from impacts
related to the construction and operation of golf courses.
Service Response: The decline of the Peninsular bighorn sheep is
attributable to a number of factors that, in combination, are
threatening the survival of this distinct population
[[Page 13140]]
segment. See the Summary of Factors Affecting the Species section for
further discussion.
Issue 13: Several commenters observed that many of the conclusions
presented in the proposed rule appear to be based on information
provided by the Bighorn Institute.
Service Response: In accordance with the Act and its implementing
regulations, the Service has used the best scientific and commercial
data available in assessing the status of the Peninsular bighorn sheep
and making the final listing determination. The Service obtained
information from various sources including the CDFG, CDPR, the Desert
Bighorn Council, published articles from scientific journals, and the
Bighorn Institute.
Issue 14: One commenter disagreed with the suggestion in the
proposed rule that depressed recruitment was probably linked to disease
throughout most of the Peninsular bighorn sheep's range. The commenter
went on to state that exposure to disease did not demonstrate a
population was declining because bighorn sheep populations commonly are
exposed to disease organisms. The commenter also recommended that
listing be delayed until further research could determine the different
factors affecting the Peninsular bighorn sheep and its decline.
Service Response: The proposed rule indicated that depressed
recruitment probably was linked to a disease epizootic. This was the
most reasonable conclusion at that time based on available information
regarding the effects of disease in the Santa Rosa Mountains and the
general decline in the number of Peninsular bighorn sheep. The presence
of recurrent disease remains a likely cause for the overall continuing
decline of Peninsular bighorn sheep numbers. However, disease is not
the only factor negatively affecting this species. The Peninsular
bighorn sheep in the United States has declined by at least 76 percent
since 1971. Another factor, in addition to disease, that has
contributed to low recruitment is an increase in predation rates (W.
Boyce and E. Rubin, in litt. 1997). The final rule indicates that
exposure to diseases such as blue tongue occurs in a significant
portion of the Peninsular bighorn sheep's range. Any delay in listing
this distinct population segment to await the results of research on
the interaction of the various threats could result in postponement of
implementation of conservation and recovery measures, thus,
contributing further to the Peninsular bighorn sheep's decline. See
Factor C in the Summary of Factors Affecting the Species Section for a
discussion of this topic.
Issue 15: One commenter stated that the effects of cattle grazing
on wild sheep needed to be re-examined because the pathogen Pasteurella
is not transmitted by cattle, but by domestic sheep. Another commenter
stated that Pasteurella had not been a problem for the Peninsular
bighorn sheep and was, therefore, not relevant to the listing.
Service Response: The Service's concerns about cattle grazing
relative to the conservation of Peninsular bighorn sheep is prompted by
the potential of cattle to harbor pathogens such as PI-3 and blue
tongue. Both of these viruses have likely contributed to Peninsular
bighorn sheep mortality. In addition, Pasteurella sp. also infect mule
deer and there is overlap in the range of mule deer, domestic sheep,
and Peninsular bighorn sheep. Although the Service is unaware of
Pasteurella sp. infections in Peninsular bighorn sheep, domestic sheep
use areas adjacent to San Jacinto Mountain and could be a source for
this infection.
Issue 16: One commenter stated that data are inadequate to
demonstrate an increase in predation, and the potential effect of this
threat on Peninsular bighorn sheep had not been assessed in the defined
range.
Service Response: The Service concurs that predation and its effect
on Peninsular bighorn sheep has not been conclusively assessed.
However, an increase in predation in the northern Santa Rosa Mountains
had been noted. Since publication of the proposed rule, further
indication of an increase in predation due to mountain lions has been
documented (W. Boyce and E. Rubin, in litt. 1997)
Issue 17: Several commenters expressed concern about the use of
current information and recommended the Service use information that is
unbiased and peer-reviewed. One commenter questioned how a listing
decision could be rendered when information is unavailable for review
or has not undergone the scrutiny of impartial analysis. This commenter
made specific reference to work being conducted by Oliver Ryder, Ph.D.
of CRES, on Weems bighorn sheep.
Service Response: As required, the Service used the best available
scientific and commercial information for the final listing decision
and all such information was accessible for public review and analysis.
However, only information related to Peninsular bighorn sheep ecology
or otherwise relevant to determining whether listing this distinct
population segment was warranted was the subject of this review.
Moreover, peer review of the listing proposal by three appropriate and
independent specialists was solicited to ensure the best biological and
commercial information was used.
Issue 18: Several commenters suggested that development within and
adjacent to Peninsular bighorn sheep habitat was not detrimental and
that the Service should focus on other causes of the decline, such as
grazing of cattle in bighorn sheep habitat. One of the commenters
stated that current mitigation measures needed to be compiled and
analyzed to determine if listing of the Peninsular bighorn sheep was
warranted.
Service Response: Populations of Peninsular bighorn sheep located
adjacent to urban development, such as golf courses and suburban
housing areas, are known to modify their behavior in non-adaptive ways.
For example, abnormally high concentrations of ewes, rams, and lambs
regularly forage and water at such developments in the Rancho Mirage
area of California throughout all months of the year (DeForge and
Osterman, pers. comm., 1997).
This altered behavior has exposed the northern Santa Rosa Mountains
ewe group to several unnatural conditions leading to relatively high
levels of mortality (DeForge 1997): excessive exposure to high levels
of fecal material increasing the chance for the spread of disease;
excessive use of an unnaturally moist environment suitable for
harboring infectious disease and parasites; unusually high levels of
adult mortality associated with predation; exposure to non-native and
potentially toxic plants; short-term lamb abandonment leading to
increased risk of lamb predation; and loss of ewe group ``memory'' of
other available water and forage areas in their historic home range
(Rubin, Ostermann, and DeForge, pers. comm., 1997). See Factors C and E
for further discussion of these issues.
Issue 19: One commenter stated that the Service had not monitored
or considered the population numbers of bighorn sheep in some mountain
ranges, such as the Little San Bernardino and Chocolate mountains.
Service Response: The bighorn sheep occurring in the Little San
Bernardino and Chocolate mountains are not a component of the distinct
vertebrate population segment under consideration in this final listing
rule. Besides the geographic separation, recent genetic research (Boyce
et al. 1997) concluded the Peninsular bighorn sheep population ``formed
a discrete group
[[Page 13141]]
with relatively high gene flow,'' whereas, the genetic distance between
three nearby Mojave populations of desert sheep including the bighorn
sheep occurring in the Little San Bernardino and Chocolate mountains
was more than three times greater. That is, the genetic distance
between the Peninsular bighorn sheep and their nearest neighbors
supports the conclusion that the Peninsular group is discrete and meets
the definition of a distinct vertebrate population segment.
Issue 20: One commenter stated there is no evidence to support the
conclusion that hikers are contributing to the decline of Peninsular
bighorn sheep.
Service Response: Peninsular bighorn sheep are sensitive to human
disturbance during critical periods, such as lambing. For example,
hikers detrimentally affect survival and recovery of this species when
this activity is in proximity to lambing areas and bighorn sheep
abandon these areas. Additional impacts occur when human activity
hinders the access of Peninsular bighorn sheep to water during times of
stress. MacArthur et al. (1979) documented a 20 percent rise in mean
heart rate when bighorn sheep were continuously exposed to people.
Another study found that areas experiencing more than 500 visitor-days
of use per year resulted in a decline of use by bighorn sheep (Graham
1971 in Purdy and Shaw 1980).
Issue 21: Several commenters stated that the bighorn sheep decline
could have been avoided. The Service should have been proactive and
worked with local land use planning agencies by providing guidance
concerning potential project-related impacts on Peninsular bighorn
sheep. In addition, one of the commenters recommended that
communication between land-use planning agencies and the Service
commence immediately and that private, State, and Federal parties be
treated equitably in the conservation process.
Service Response: The Service has long been involved with local
planning agencies within the range of the Peninsular bighorn sheep as a
technical adviser. Recommendations of the Service have not always been
incorporated into project design and location resulting in
irretrievable impacts (see Response to Issue 18). The Service concurs
that all involved parties should be treated equitably during future
efforts to conserve and recover the species.
Issue 22: One commenter stated that the grazing of cattle on
Federal lands should be terminated where the activity may impact
Peninsular bighorn sheep. The commenter also stated that movement
corridors should be conserved.
Service Response: The Service contends that activities impacting
Peninsular bighorn sheep should be avoided to the extent possible and
endorses the conservation of movement corridors. Upon the listing of
the Peninsular bighorn sheep, the issue of cattle grazing and movement
corridors will be evaluated, and appropriate actions to be taken will
be identified as part of the species conservation and recovery process.
Issue 23: One commenter stated that the Peninsular bighorn sheep
would benefit from the addition of golf courses.
Service Response: The Service is unaware of scientific information
demonstrating that golf courses are beneficial to the long-term
survival and recovery of Peninsular bighorn sheep. There is evidence
that golf courses negatively impact Peninsular bighorn sheep through
the spread of parasites (e.g., hookworms) and availability of toxic
plants such as oleander. Furthermore, golf courses do not provide ideal
forage for this species and the associated human activity disrupts the
normal behavioral patterns of bighorn sheep (see Response to Issue 18).
Issue 24: One commenter recommended that the Peninsular bighorn
sheep be relocated where interaction with people would be less likely
to occur.
Service Response: The Peninsular bighorn sheep have specific
habitat requirements within the Peninsular Mountain Ranges of southern
California. The removal of an animal from its native habitat to another
location provides no assurance of survival. For listed species, such
removal and relocation would have to meet recovery and conservation
objectives to be consistent with purposes of the Act.
Issue 25: Several commenters suggested it was unlikely that Federal
listing of this population would result in protection beyond that
already provided by the California Environmental Quality Act (CEQA) and
CESA. In addition, the commenters predicted that Federal listing may be
detrimental by making the approval process for bighorn sheep
reintroductions or management actions more complex.
Service Response: Federal listing of the Peninsular bighorn sheep
will complement the protection options available under State law
through measures discussed below in the ``Available Conservation
Measures'' section. The Service will use established procedures to
evaluate management actions necessary to achieve recovery of the
species and thereby avoid any undue implementation delays. In addition,
Federal listing would provide additional resources for the conservation
of the species through sections 6 and 8 of the Act.
Issue 26: Several commenters stated that listing of the Peninsular
bighorn sheep was unnecessary because effective voluntary efforts exist
for safeguarding this species at no public cost. Furthermore, the
existing population occurs almost exclusively on lands administered by
State or Federal agencies on which private actions will not occur.
Service Response: Voluntary efforts are important to conservation
of Peninsular bighorn sheep, but, to date, these efforts have not
stabilized or reversed the numerical decline. The effects of urban and
commercial development, disease, and predation continue to represent
foreseeable threats to this distinct population segment. The inadequacy
of existing regulatory mechanisms to stabilize or reverse the decline
is discussed in Factor D.
Issue 27: Several commenters stated that the Service has ignored
existing efforts to conserve the Peninsular bighorn sheep. In addition,
one of these commenters recommends the Service consider the
metapopulation approach to the management of wild sheep in California.
This same commenter explained that the Peninsular Ranges population of
bighorn sheep probably represents one of the most intact
metapopulations of this species from the standpoint of demography and
corridors connecting demes.
Service Response: Several State and Federal management plans have
been prepared for bighorn sheep. However, these plans have not
effectively reversed the decline of the Peninsular bighorn sheep
population. Federal listing will complement and add to these
conservation efforts. Existing management plans and the population
ecology of the Peninsular bighorn sheep will be important components in
the development of a recovery plan.
Issue 28: One commenter discussed the history of bighorn sheep
management in Mexico and indicated that it had been ineffective in the
past. The commenter also stated that the current program has inadequate
resources for addressing threats on bighorn sheep such as poaching,
disease exposure, and habitat loss from feral livestock. The commenter
concluded that listing of the Peninsular bighorn sheep may
substantially contribute to
[[Page 13142]]
the conservation and recovery of these animals.
Service Response: Based on information received during the last
comment period extension, the Mexican Government established a new
conservation program in April 1997 for bighorn sheep in Baja
California, Mexico. Given that there are significantly more bighorn
sheep in Baja California, Mexico, as compared to southern California,
there is more time to ascertain the effectiveness of the conservation
program and the status of Peninsular bighorn sheep in this area. If the
population of Peninsular bighorn sheep decline under the Mexican
Government's conservation program, future listing of the animals may be
appropriate.
Issue 29: One commenter stated that Mexican authorities had not
been properly consulted and these authorities did not support listing.
Service Response: As required, the Service corresponded on February
21, 1992, and June 8, 1992, with the Mexican government when the
Peninsular bighorn sheep was proposed for listing. Moreover, the
Service reopened the public comment period on October 27, 1997, for an
additional 15 days to acquire additional information on the status,
distribution, and management of bighorn sheep in Baja California,
Mexico. Comments were received from the Mexican government during this
third, and last, comment period extension and were considered in making
the final listing determination.
Issue 30: One commenter stated the Service that the purpose of the
Act was to conserve wild species. The commenter stated that the
proximity of the Bighorn Institute to private development was,
therefore, not a legitimate justification for proposing the species as
endangered.
Service Response: The Service concurs with the commenter about
conservation of species in the wild (i.e., ``conserve wild species'').
The Bighorn Institute and Living Desert Museum maintain captive
populations of Peninsular bighorn sheep for scientific and educational
purposes. This use is thought to have no negative impact on free-
ranging bighorn. However, the fact that the Bighorn Institute is
located close to residential/commercial development was mentioned in
the proposed rule as an indirect factor affecting Peninsular bighorn
sheep.
Issue 31: Several commenters criticized the Service for not
addressing the economic impacts of listing the Peninsular bighorn sheep
population as endangered. One of these commenters stated that the
Peninsular bighorn sheep should not be listed if it would stifle
economic development.
Service Response: In accordance with 16 U.S.C. Sec. 1533(b)(1)(A)
and 50 CFR 424.11(b), listing decisions are made solely on the basis of
the best scientific and commercial data available. In adding the word
``solely'' to the statutory criteria for listing a species, Congress
specifically addressed this issue in the 1982 amendments to the Act.
The legislative history of the 1982 amendments states: ``The addition
of the word ``solely'' is intended to remove from the process of the
listing or delisting of species any factor not related to the
biological status of the species. The Committee strongly believes that
economic considerations have no relevance to determinations regarding
the status of species and intends that the economic considerations have
no relevance to determinations regarding the species' status.
Issue 32: One commenter indicated that a 30 day comment period for
the listing proposal was inadequate and the continued processing of the
proposed rule was prohibited by the Act.
Service Response: The Service has provided ample opportunity for
public comment during this rule making process. The initial comment
period for the proposed rule was open for 6 months. The Service
reopened the comment period for an additional 30 days on April 7, 1997
(62 FR 16518), for an additional 15 days on June 17, 1997 (62 FR
32733), and then again for an additional 15 days on October 27, 1997
(62 FR 55564). See discussion under Previous Federal Action for added
details.
Issue 33: One commenter stated that the Peninsular bighorn sheep
should not be listed because once listed it becomes impossible to
remove species from the list, and expressed concern regarding the
closure of mountain areas to recreationists.
Service Response: A principal goal of the Service for listed
species is to recover species to a point at which protection under the
Act is no longer required. When the recovery goals for a species have
been met, the Service may prepare a proposal to delist or reclassify
the species based on the best available scientific and commercial
information. The process for delisting or reclassifying a species, per
section 4(b)(3)(A) of the Act, is similar to that used for listing.
Regarding closure of mountain areas to recreationists, certain
locations of special sensitivity, such as lambing areas, may be closed
to prevent disturbance and promote the recovery of the Peninsular
bighorn sheep. Most other recreational use restrictions would be
unchanged.
Issue 34: One commenter recommended that the Service designate
critical habitat concurrently with the listing of the Peninsular
bighorn sheep. A second commenter disagreed with the Service's
rationale for not proposing critical habitat but made no recommendation
concerning the designation of critical habitat. Another commenter
indicated that designation of critical habitat would not lead to
increased poaching of the Peninsular bighorn sheep because of State
listing and protection regulations. Commenters also stated that the
discussions under the Critical Habitat and Available Conservation
Measures sections in the proposed rule were contradictory.
Service Response: The Service has determined that designation of
critical habitat would increase the threat of human activities to
Peninsular bighorn sheep and that such a designation would not be
beneficial to the species. The identification of such areas on critical
habitat maps would likely call attention to the locations of bighorn
sheep (especially lambing areas) and increase the degree of threat from
human intrusion. Moreover, protection of habitat and other conservation
actions are better addressed through recovery planning and section 7
consultation processes.
The discussions under Critical Habitat and Available Conservation
Measures are not contradictory with respect to section 7. The Available
Conservation Measures section addresses the conservation actions that
result from listing. With or without critical habitat, Federal agencies
are required to consult with the Service if an action may affect a
listed species. Critical habitat is mentioned under Available
Conservation Measures because regulations pertaining to section 7(a),
7(a)(2) and 7(a)(4) are reiterated. The responsibility of Federal
agencies is discussed in general, and not in terms specifically related
to the Peninsular bighorn sheep. For further discussion of this issue
see the Critical Habitat section.
Summary of Factors Affecting the Species
After a thorough review and consideration of all information
available, the Service has determined that the Peninsular bighorn sheep
should be classified as an endangered distinct population segment.
Procedures found at section 4 of the Act and regulations (50 CFR part
424) promulgated to implement the listing
[[Page 13143]]
provisions of the Act set forth the procedures for adding species to
the Federal Lists. A species may be determined 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 Peninsular bighorn
sheep distinct population segment (Ovis canadensis) are as follows:
A. The present or threatened destruction, modification, or
curtailment of its habitat or range. Peninsular bighorn sheep have been
extirpated from several historic locations, including the Fish Creek
Mountains (Imperial County) and the Sawtooth Range (San Diego County)
(DeForge et al., 1993). In the United States, the number of Peninsular
bighorn sheep has declined from an estimated 1,171 individuals in 1971
to about 280 individuals in 1997 (DeForge et al. 1995; J. DeForge, in
litt. 1997; E. Rubin and W. Boyce, in litt. 1996; W. Boyce and E.
Rubin, in litt, 1997). Habitat loss (especially canyon bottoms),
degradation, and fragmentation associated with the proliferation of
residential and commercial development, roads and highways, water
projects, and vehicular and pedestrian recreational uses are threats
contributing to the decline of Peninsular bighorn sheep throughout its
range.
Peninsular bighorn sheep are susceptible to fragmentation due to
the distribution of habitat (narrow band at low elevation), use of
habitat (e.g., occupying low elevations), and population structure.
Restricted to elevations below the distribution of chaparral habitat
(typically about 1,050 m (3,500 ft)), encroaching urban development and
human related disturbance have the dual effect of restricting remaining
animals to a smaller area and severing connections between ewe groups.
The Peninsular bighorn sheep distinct population segment, like other
bighorn sheep populations, is composed of ewe groups that inhabit
traditional areas (cluster of canyons) and rams that move among these
groups exchanging genetic material. Maintenance of genetic diversity
allows small ewe groups to persist. The inability of rams and
occasional ewes to move between groups erodes the genetic fitness of
isolated groups. Urban and commercial development may ultimately
fragment the metapopulation into isolated groups too small to maintain
long-term viability, as apparently was the case in the extirpation of
one ewe group in the United States in the recent past.
Urban development and associated increases in human activities in
bighorn sheep habitat were reported to be the leading cause of
extinction of an entire bighorn sheep population (ewes, rams, and
lambs) in Tucson, Arizona (Krausman, pers. comm. 1997). In the River
Mountains, Nevada, 9 of 17 marked desert bighorn sheep ewes altered
their normal watering patterns; seven of these ewes abandoned the site
(Leslie and Douglas 1980). Leslie and Douglas (1980) noted that,
because ewes are more restricted in their movements and display a
relatively high degree of fidelity to water sources, such abrupt
changes in watering patterns are probably the result of extrinsic
disturbances. Development has resulted in habitat abandonment in other
bighorn sheep populations (Ferrier 1974). Other researchers have
maintained that recreational encroachment can be most damaging during
critical periods of the year for bighorn sheep, such as lambing (Geist
1971, Light 1973, Cowan 1974).
Abandonment of preferred habitat is anticipated to be detrimental
to the long-term survival of Peninsular bighorn sheep. Abandonment of a
lambing area in the Peninsular Ranges has been reported, and it has
been attributed to human activities. The construction of a flood
control project took place in Magnesia Canyon within the City of Rancho
Mirage in 1982. This construction took place below a lambing area that
was occupied by the northern Santa Rosa Mountains (SRM) ewe group.
During the construction of the flood control project, the northern SRM
ewe group relocated their lambing area from Bradly Peak (above Magnesia
Canyon, and in direct line of site to the flood control project area)
to Ramon Peak (DeForge, pers. comm., 1997). The distance between these
two lambing areas is estimated at about 2.4 km (1.5 mi). Ramon Peak is
situated away from areas occupied by humans, and human activities were
correspondingly absent compared to Magnesia Canyon during construction.
This relocation corresponded to the shift in habitat use and
abandonment of some areas affected by the noise and view of humans
during construction observed by DeForge and Scott (1982). DeForge and
Scott (1982) also observed a marked difference in behavior when ewes
with lambs used a watering area located 200 to 500 m (660 to 1650 ft)
from the construction area. As further evidence that the abandonment of
the lambing area was attributable to human activities, DeForge (pers.
comm., 1997) also indicated that the ewe group re-occupied the Bradly
Peak lambing area the following year after construction and human
activities subsided. Approved and future projects such as Shadowrock
Golf Course and Mountain Falls Golf Course, respectively, may result in
the abandonment of the main remaining lambing area in the San Jacinto
Mountains.
The Coachella Valley Association of Governments anticipates that by
the year 2010 the human population there will increase from 227,000 to
over 497,000, not including 165,000 to 200,000 seasonal residents. In
1989, the population of Imperial County was 116,000. The cities of El
Centro, Imperial, and Calexico grew by about one-third between 1980 and
1989 (Bureau of Reclamation 1991). Increased human populations and
associated commercial and residential development will likely continue
to increase destruction of habitat and disrupt sheep behavioral
patterns.
B. Overutilization for commercial, recreational, scientific, or
educational purposes. There is no open hunting season for Peninsular
bighorn sheep in the United States. Although the limited opportunities
for desert bighorn hunting in California create a temptation for taking
without a license, poaching does not appear to be a problem at this
time.
The Bighorn Institute and Living Desert Museum maintain captive
populations of Peninsular bighorn sheep for scientific and educational
purposes. This use is thought to have no negative impact on free-
ranging bighorn.
C. Disease or predation. Disease is a major factor responsible for
the precipitous decline of Peninsular bighorn sheep in the northern
Santa Rosa Mountains and appears to significantly contribute to
population declines elsewhere throughout its range. Elliott et al.
(1994) found a higher level of exposure to viral and bacterial
pathogens in the Peninsular bighorn sheep population than in other
California bighorn sheep populations. Past higher exposure to pathogens
suggests that disease may have been a major contributing factor in this
distinct population segment's decline.
Bighorn sheep are susceptible to a variety of bacterial, fungal,
and viral infections (DeForge et al. 1982, Turner and Payson 1982,
Clark et al. 1985). Lambs and older sheep may be most susceptible to
disease. Numerous endoparasites and ectoparasites are known to occur in
this species (Russi and Monroe 1976, Lopez-Fonseca 1979). The
relationship between disease, its transmission, and factors such as
stress, density, competition, water availability, and disturbance are
not well understood. Disease manifestation
[[Page 13144]]
probably occurs during stressful periods such as high or low population
levels, reproductive activity, low nutrient availability, and climatic
extremes (Taylor 1976, Turner and Payson 1982).
Disease is responsible for high lamb mortality rates in Peninsular
bighorn sheep (Sanchez et al. 1988). In the northern Santa Rosa
Mountains, excessive lamb mortality has occurred since 1977 (DeForge et
al. 1995). DeForge et al. (1982) reported evidence that bighorn sheep
lamb mortality in the Santa Rosa Mountains was due to pneumonia.
Bacterial pneumonia is usually a sign of weakness caused by another
agent such as a virus, parasite, or environmental stress that lowers an
animal's resistance to disease. DeForge and Scott (1982) reported
serological evidence that a combination of parainfluenza-3 (PI-3), blue
tongue (BT), epizootic hemorrhagic disease (EHD), and contagious
ecthyma (CE) viruses may be contributing initiating factors for the
development of pneumonia in the Santa Rosa Mountains ewe group. In
addition to exposure to the above mentioned diseases, antibody titers
to respiratory syncytial virus (RSV) have been found in Peninsular
bighorn sheep (Clark et al. 1985). Poor nutrition, predation, climatic
changes, and human related impacts may contribute to high lamb
mortality. Vaccination experiments have been conducted for BT and PI-3.
Vaccines for PI-3 have been used with limited success in captive and
wild sheep (Jessup et al. 1990).
Domestic and feral cattle can act as disease reservoirs. Several
viruses discovered in sick bighorn sheep lambs were non-native and
thought to be introduced by domestic livestock (DeForge, in litt.
1988). However, the potential role of livestock in disease transmission
is not well understood. Staff of the Anza-Borrego Desert State Park
(Park) completed a project to remove 119 feral cattle from the Park in
1990. Six types of viruses were detected in these cattle. Blood samples
taken from cattle grazing in allotments adjacent to Peninsular bighorn
sheep habitat within the Park have contained several viruses.
Peninsular bighorn sheep in Mexico have also tested positive to
exposure to viral and bacterial diseases (J. DeForge, pers. comm.,
1997).
Other livestock may transmit diseases as well. Domestic sheep
harbor bacteria (Pasteurella sp.) and viruses such as BT that can kill
bighorn sheep, and close contact results in transmission to and the
subsequent death of most or all of the exposed animals (Foreyt and
Jessup 1982). Although no grazing allotments for domestic sheep have
been issued by BLM or USFS in the Peninsular Ranges, the potential for
their presence exists. Domestic sheep associated with commercial
operations have been observed in the San Jacinto River along the
northern edge of the San Jacinto Mountains. In addition, small numbers
of domestic sheep are raised by private individuals living along the
northern edge of the San Jacinto Mountains (A. Davenport, Fish and
Wildlife Service, pers. obs. 1993).
Cattle or domestic sheep do not have to occupy Peninsular bighorn
sheep habitat for disease transmission to occur. For example, Jessup et
al. (1985) has found antibodies for this pathogen in mule deer. Blue
tongue, a disease transmitted by a biting midge (Culicoides sp.),
occurs in animals such as cattle, sheep, goats, mule deer, and bighorn
sheep. Cattle appear to be capable of harboring the virus (Wallmo 1981,
Jessup 1985, Jessup et al. 1990). Overlap in habitat use by Peninsular
bighorn sheep, southern mule deer, and the biting midge may provide a
pathway for disease transmission from deer populations associated with
livestock to bighorn sheep. This pathway may involve either movement of
an infected individual or the progression of an epizootic through the
general deer population to Peninsular bighorn sheep where the two
species overlap.
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 Peninsular bighorn
sheep. This situation is exacerbated by the presence of cattle and
other livestock in and adjacent to areas occupied by Peninsular bighorn
sheep.
Urban developments such as golf courses and associated housing
areas also influence the effect of disease and predation on the
Peninsular bighorn sheep. For example, high concentrations of ewes,
rams, and lambs regularly forage and water at such developments in the
Rancho Mirage area of California throughout all months of the year
(DeForge and Osterman, pers. comm., 1997).
This behavior has exposed the northern Santa Rosa Mountains ewe
group to several unnatural conditions leading to relatively high levels
of mortality (DeForge 1997): excessive exposure to high levels of fecal
material increasing the chance for the spread of disease; excessive use
of an unnaturally moist environment suitable for harboring infectious
disease and parasites; unusually high levels of adult mortality
associated with predation; exposure to non-native and potentially toxic
plants; short-term lamb abandonment leading to increased risk of lamb
predation; and loss of ewe group ``memory'' of other available water
and forage areas in their historic home range (Rubin, Osterman, and
DeForge, pers. comm., 1997).
DeForge and Ostermann (in prep.) reported that urbanization was the
leading known cause of death to Peninsular bighorn sheep occupying the
northern Santa Rosa Mountains. During their investigation in the
northern Santa Rosa Mountains, urbanization accounted for 34.2 percent
of all recorded adult mortalities. Mortalities directly caused by
urbanization were associated with ingestion of toxic, non-native
plants, automobile collisions, and fences. Indirect causes of death
associated with urbanization included parasite infestations and altered
habitat use.
Exposure to high concentrations of feces can lead to unnaturally
high levels of exposure to disease and parasites (Georgi 1969), and may
contribute to Peninsular bighorn sheep population declines. Development
in and adjacent to the Santa Rosa Mountains has established irrigated
grass lawns, golf courses, and ponded waters providing environmentally
suitable conditions for the strongyle parasite to successfully complete
its life cycle, and increase its presence in a naturally arid
environment. Sheep can be exposed to the strongyle parasite from the
feces of an infected individual (Georgi 1969). Strongyle parasites have
been reported in the northern Santa Rosa Mountains ewe group (DeForge
and Osterman 1997). Animals exhibiting symptoms from the infection of a
strongyle parasite are less active, forage less, tend to stay unusually
close to water sources, become weak, are extremely emaciated, and
exhibit anemia (Georgi 1969). Mortality from infection of the strongyle
parasite may be experienced in sheep, particularly under situations
that create additional stress (Georgi 1969).
Strongyle parasites are common in domestic ruminant, horse, and pig
hosts, and require moist environments for the survival of its larval
stages outside of the host. The strongyle parasite life cycle cannot be
completed in arid environments, and strongyle infestations are
generally rare in desert regions (Georgi 1969). However, between 1991
and 1996, more than 85 percent of the Peninsular bighorn sheep sampled
in the Santa Rosa Mountains ewe group were infected with the strongyle
parasite (DeForge and Osterman, unpubl. data). Ewes, rams, and lambs
are susceptible to infection
[[Page 13145]]
with the strongyle parasite. Clinical signs of strongyle parasites in
the Peninsular bighorn sheep have been reported only from the Santa
Rosa Mountains ewe groups. Strongyle parasites have not been detected
in the San Jacinto Mountains (SJM) ewe groups, and are considered rare
or absent in other ewe groups.
Peninsular bighorn sheep exhibiting physiological stress related to
an infestation of the strongyle parasite are at greater risk of
predation, and less likely to successfully reproduce. Presently, there
is no local or regional program to inoculate Peninsular bighorn sheep
against non-native, introduced diseases, viruses, and parasites.
The reduction of disease outbreaks centers, in large part, on
reducing factors that stress Peninsular bighorn sheep. Stress
predisposes animals to disease (DeForge 1976). One of the major factors
that stress bighorn sheep is human encroachment into their habitat. The
decline of the Peninsular bighorn sheep is markedly steeper where the
population borders the developing areas of the Coachella Valley. The
decline in the population adjacent to urban areas in the Coachella
Valley has been 35 percent greater than that occurring in Anza Borrego
Desert State Park. Disease has been documented as an important factor
in the decline of the population in the northern Santa Rosa Mountains
(DeForge and Scott 1982, DeForge et al. 1982). Although the pathogens
responsible for the diseases in the Santa Rosa Mountains have also been
detected in Anza Borrego Desert State Park (Elliott et al. 1994), the
population in Anza Borrego Desert State Park has declined at a slower
rate (57 percent versus 92 percent).
Increased risk of predation has also been attributed to unnatural
environments found at the urban interface. DeForge (pers. comm., 1997)
has observed higher numbers of adult Peninsular bighorn sheep
mortalities caused by mountain lions (Felis concolor) closer to the
urban environment as compared to wild lands. Domestic dogs often occur
along the urban-wild lands interface, and are also capable of injuring
and killing lambs, ewes, and young or unhealthy rams. Encroaching
development not only increases the abundance of domestic dogs along the
urban-wild lands interface, but also creates unnatural landscape
characteristics such as hedge rows, dense patches of tall vegetation,
and other unnatural cover suitable for predators to hide and ambush
potential prey. The Service has received complaints from residents of
Thunderbird Cove that the presence of Peninsular bighorn sheep feeding
on lawns attracts mountain lions, which some of the residents have
observed.
Natural predation is not known to be a limiting factor in free-
roaming desert bighorn sheep populations having adequate escape cover
(Blaisdell 1961, Elliot 1961, and Weaver 1961). According to Wilson
(1980), predation, as a mortality factor, decreases in significance as
the size of a population increases. In addition, major predation
problems have occurred with populations occupying restricted home
ranges or fenced areas (Cooper 1974, Kilpatrick 1975). Compared to the
northern Santa Rosa Mountains ewe group, ewe groups to the south, the
majority of which do not occupy restricted home ranges, have
experienced high rates of natural predation compared to urban-related
mortalities (Boyce 1995). Ewe group sizes in these areas are larger
than the northern Santa Rosa Mountains and San Jacinto Mountains ewe
groups, and can likely tolerate such predation levels.
Coyote (Canis latrans), bobcat (Lynx rufus), mountain lion, gray
fox (Urocyon cinereoargenteus), golden eagle (Aquila chryseatos), and
free-roaming domestic dogs prey upon bighorn sheep. Predation generally
has an insignificant effect except on small populations. In recent
years, mountain lion predation of Peninsular bighorn sheep appears to
have increased in the northern Santa Rosa Mountains (J. DeForge, pers.
comm., 1991, W. Boyce and E. Rubin, in litt. 1997) and sheep encounters
with domestic dogs are likely to increase with more urban development.
The deaths of several radio-collared Peninsular bighorn sheep in Anza
Borrego State Park have been attributed to mountain lions (W. Boyce and
E. Rubin, in litt. 1997).
D. The inadequacy of existing regulatory mechanisms. The Peninsular
bighorn sheep has been listed as threatened by the State of California
since 1971 (CDFG 1991). 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. The CESA requires that
State agencies consult with the CDFG to ensure that actions carried out
are not likely to jeopardize the continued existence of listed species.
However, most of the activities occurring within the range of the
Peninsular bighorn sheep are not State authorized, funded, or
permitted, resulting in few consultations under the CESA.
Shadowrock Golf Course and Altamira represent examples of locally
approved projects that could have significant adverse effects on the
Peninsular bighorn sheep. The City of Palm Springs approved the
Shadowrock project which would eliminate important canyon bottom
habitat and compromise or curtail sheep movement corridors. In
addition, a settlement agreement between the developer of Shadowrock
and the CDFG allows the project to proceed with only minor changes from
the original design. Similarly, the City of Palm Springs has processed
the Andreas Cove project proposal under a Negative Declaration, rather
than the more rigorous Environmental Impact Report analysis. Moreover,
the General Plans for most of the cities in the Coachella Valley
inadequately address potentially significant development threats to the
long-term conservation of Peninsular bighorn sheep. The Service is
aware of approximately 15 additional project proposals that have the
potential to adversely effect this species.
Regional conservation planning efforts are underway within the
range of the Peninsular bighorn sheep, but these efforts are either
incomplete, awaiting funding and implementation, or unproven for this
distinct population segment. Given the development pressures and
history of project approval in the Coachella Valley, the Service is
concerned for the remaining Peninsular bighorn sheep in this area.
The Peninsular bighorn sheep receives some benefit from the
presence of least Bell's vireo (Vireo bellii pusillus) and southwestern
willow flycatcher (Empidonax traillii extimus) in its range; both are
federally listed species. However, this benefit is limited due to the
specialized habitats (riparian woodland) utilized by these birds.
Similarly, section 404 of the Clean Water Act provides limited
protection to small portions of the Peninsular bighorn sheep's range
through the U.S. Army Corps of Engineers' (Corps) regulation of the
discharge of dredged and fill material into certain waters and wetlands
of the United States.
The California Fish and Game Code provides for management and
maintenance of bighorn sheep. The policy of the State is to encourage
the preservation, restoration, utilization, and management of
California's bighorn sheep. The CDFG supports the concept of separating
livestock from bighorn sheep (to create buffers to decrease the
potential for disease transmission) through purchase and elimination of
[[Page 13146]]
livestock allotments. However, it has not been a policy of the CDFG to
revoke current State livestock permits (State of California 1988), nor
does the State have authority to regulate grazing practices on Federal
lands. Accordingly, State listing has not prompted the BLM or USFS to
effectively address disease transmission associated with Federal
livestock grazing programs.
Since the Peninsular bighorn sheep was listed by the State of
California in 1971, the CDFG has: (1) prepared management plans for the
Santa Rosa Mountains and for the McCain Valley area of eastern San
Diego County; (2) acquired 30,000 acres of land in the Santa Rosa
Mountains; (3) initiated demographic, distributional, and disease
research; and (4) established three ecological reserves that protect
important watering sites. These actions are important to Peninsular
bighorn sheep conservation, but, are not sufficient to stem the long-
term population decline.
The BLM and the USFS manage lands that contain habitat for
Peninsular bighorn sheep. The BLM has management plans that include
management activities for the Peninsular bighorn sheep. The San
Bernardino National Forest Plan also addresses the Peninsular bighorn
sheep. Both agencies administer grazing allotments on portions of their
land. The Bureau of Indian Affairs, Bureau of Reclamation, and the
Department of Defense also conduct activities within or adjacent to the
range of this distinct population segment. The BLM, CDFG, CDPR, USFS
Service, and Service are jointly developing the Peninsular Ranges
Coordinated Bighorn Sheep Metapopulation Management Plan (BLM et al.
1993). The completion of this plan is pending. Current Federal
management plans have not stopped the decline in numbers of Peninsular
bighorn sheep on Federal lands.
E. Other natural or manmade factors affecting its continued
existence. Recurrent drought, disturbance at watering sites, urban and
agricultural water withdrawals, and domestic livestock use decrease the
amount of water available for Peninsular bighorn sheep. In particular,
small ewe groups are affected. Peninsular bighorn sheep, similar to
other bighorn sheep, exhibit a seasonal pattern of distribution based
on forage and water availability. Water is available via tenajas
(natural catchment basins adjacent to streams), springs, and guzzlers.
During late summer and early winter (July to November), when water
requirements and breeding activities are at a peak, the sheep tend to
concentrate near water sources, particularly as tenajas and springs dry
up. During this time, the sheep depend on reliable water and food
sources. Bighorn sheep require a quantity of water approximately equal
to 4 percent of their body weight (1 gallon) per day during the summer
months and a dependable water supply is needed at about 2-mile
intervals (Blong and Pollard 1968). When water is not available in
sufficient quantities (especially during hot, dry weather) the
mortality rate for older sheep, lambs, and sick or injured animals is
likely to increase.
Several studies have shown that bighorn sheep respond to human
presence (as well as roads and housing developments) by altering
behavior patterns to avoid contact. This behavioral response may
preclude or disrupt sheep use of essential water sources, mineral
licks, feeding areas, or breeding sites (Hicks and Elder 1979, Hamilton
et al. 1982, MacArthur et al. 1982, Miller and Smith 1985, Krausman and
Leopold 1986, Sanchez et al. 1988). Proposed country club/residential
developments that have been approved or proposed within or immediately
adjacent to Peninsular bighorn sheep habitat will substantially
increase human activity. Unrestricted use of hiking and mountain bike
trails in sensitive areas could further disrupt bighorn behavior and
negatively affect this species. A reversal in behavior has been noted
by the immediate return of Peninsular bighorn sheep to areas that were
recently closed off to hikers in the Santa Rosa Mountains (e.g.,
Magnesia Falls Canyon) (Ken Corey, U.S. Fish and Wildlife Service,
pers. com., 1997)
Some species of ornamental plants, associated with urban
developments, have been attributed to causes of mortality in bighorn
sheep (Wilson et al. 1980, DeForge 1997). Between 1991 and 1996, five
Peninsular bighorn sheep in the northern Santa Rosa Mountains ewe group
died from ingesting ornamental, toxic plants such as oleander (Nerium
oleander) and laurel cherry (Prunus sp.) (DeForge and Ostermann 1997).
A toxic, ornamental nightshade plant may have caused the death of a
young ram (a necropsy revealed an unknown species of nightshade) in
Palm Springs in 1970 (Weaver and Mensch 1970). Due to the absence of
comprehensive studies of the toxicity of ornamental plants to bighorn
sheep, only the two plant species mentioned above are known to be
poisonous to the Peninsular bighorn sheep. It is expected that more
species of ornamental plants are toxic to this species (DeForge, pers.
comm. 1997).
Collisions with vehicles also are a source of Peninsular bighorn
sheep mortality. Turner (1976) reported Peninsular bighorn sheep being
killed as a result of automobile collisions on Highway 74 in areas
where blind curves exist in known sheep movement areas. The Thunderbird
Estates and golf course is located across Highway 111 (on the east
side) from Peninsular bighorn sheep habitat in Rancho Mirage.
Individuals from the northern Santa Rosa Mountains ewe group cross over
Highway 111, or use a flood control channel that is under Highway 111,
to access forage and water at this golf course (DeForge, pers. comm
1997). Dominant ewes will lead five to seven other ewes and rams to the
golf course across Highway 111 which has led to collisions with
automobiles (DeForge, pers. comm. 1997). DeForge and Ostermann (1997)
also reported that nine Peninsular bighorn sheep in the Santa Rosa
Mountains were hit and killed by automobiles between 1991 and 1996, and
in combination with other urban-related factors, accounted for the
majority of mortalities.
The Peninsular bighorn sheep apparently is currently functioning as
a metapopulation (BLM et al. 1993, Boyce et al. 1997); there is
interaction between separate groups. However, the potential loss of
dispersal corridors and habitat fragmentation by residential and
commercial development and roads and highways may isolate certain
groups. Isolation increases the chances for inbreeding depression by
preventing rams from moving among ewe groups and eliminating
exploratory and colonizing movements by ewe groups into new or former
habitat. Inbreeding and the resultant loss of genetic variability can
result in reduced adaptiveness, viability, and fecundity, and may
result in local extirpations. Small, isolated groups are also subject
to extirpation by naturally occurring events such as fire. Although
inbreeding has not been demonstrated in the Peninsular bighorn sheep,
the number of sheep occupying many areas is critically low. The minimum
size at which an isolated group 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).
Berger (1990) studied bighorn sheep populations in the southwestern
United States and found that all populations with less than 50
individuals became extinct within 50 years. Berger (1990) concluded
that extinction in
[[Page 13147]]
populations of this size cannot be overcome without intensive
management, because 50 individuals, even in the short-term, do not
constitute a viable population size. This issue is complicated because
of the structure and function of bighorn sheep populations. Because
they appear to be functioning as a type of metapopulation, the
effective size of a population is actually larger. That is, adjacent
groups must be taken into consideration in determining the long-term
viability of a group or an assemblage of groups. For example, connected
groups (ewe herds) can be isolated from the other groups through the
loss of intervening groups. The loss of an intervening group is
detrimental to the long-term viability of the overall population due to
the loss itself, and through the potential genetic and demographic
isolation of the remaining groups. Other causes of mortality such as
road kills may significantly affect the continued survival of small
groups that are experiencing depressed recruitment.
The Service has carefully assessed the best scientific and
commercial information available regarding the past, present, and
future threats faced by this distinct vertebrate population segment in
determining to make this rule final. Based on this evaluation, the
Service finds that the Peninsular bighorn sheep is in danger of
extinction throughout a significant portion of its range due to: (1)
disease; (2) insufficient lamb recruitment; (3) habitat loss,
degradation, and fragmentation by urban and commercial development; and
(4) predation coinciding with low population numbers. Because of the
threats and the decline of the species, the preferred action is to list
the Peninsular bighorn sheep as endangered. Threatened status would not
accurately reflect the rapid, ongoing decline of, and imminent threats
to, the Peninsular bighorn sheep.
Status of Peninsular Bighorn Sheep Currently Held in Captivity
Under section 9(b)(1) of the Act, certain prohibitions applicable
to listed species would not apply to Peninsular bighorn sheep held in
captivity or in a controlled environment on the date of publication of
any final rule, provided that such holding and subsequent holding or
use of these sheep was not in the course of a commercial activity. In
addition, certain prohibitions applicable to listed species would not
apply to Peninsular bighorn sheep taken by hunters prior to publication
of this final rule.
Critical Habitat
Critical habitat is defined in section 3 of the Act as: (i) the
specific areas within the geographical area occupied by a species, at
the time it is listed in accordance with the Act, on which are found
those physical or biological features (I) essential to the conservation
of the species and (II) that may require special management
considerations or protection; and (ii) specific areas outside the
geographical area occupied by a species at the time it was listed, upon
a determination that such areas are essential for the conservation of
the species. ``Conservation'' means the use of all methods and
procedures needed to bring the species to the point at which listing
under the act is no longer required.
Section 4(a)(3) of the Act, as amended, and its implementing
regulations (50 CFR 424.12) require that, to the maximum extent prudent
and determinable, the Secretary designate critical habitat at the time
a species is determined to be endangered or threatened. The Service
finds that designation of critical habitat is not prudent for the
Peninsular bighorn sheep distinct population segment. Service
regulations (50 CFR 424.12(a)(1)) state that designation of critical
habitat is not prudent when one or both of the following situations
exist: (1) the identification of critical habitat can be expected to
increase the degree of threat to the species, or (2) such designation
of critical habitat would not be beneficial to the species.
The Service concludes that critical habitat designation for the
Peninsular bighorn sheep is not prudent because both of the described
situations exist. Bighorn sheep life history research and population
status surveys have been conducted for over 40 years (DeForge et al.
1995) and much of this work is ongoing. As a consequence, the
distribution and location of Peninsular bighorn sheep in the United
States are well known within the scientific community. The Peninsular
bighorn sheep is a majestic and popular animal in the eyes of the
general public. Attractive areas for recreational hiking and possible
observation points for Peninsular bighorn sheep have been identified in
commercially available information sources (Palm Springs Desert Access
Guide (BLM 1978); Santa Rosa Mountains National Scenic Area Trails Map
(Coachella Valley Trails Council 1995); Palm Canyon Trail Map 1995).
The cumulative pressure of human attraction to the scenic canyons and
mountains occupied by bighorn sheep has led to the proliferation of
new, unauthorized trails that are becoming an increasing concern of
land management agencies and scientific organizations. Annual aerial
censuses by the Bighorn Institute and CDFG recently identified several
new trails through important habitat areas in the vicinity of La Quinta
(J. DeForge, pers. comm., 1998). Similarly, BLM recently discovered a
newly constructed trail on its lands in the hills above Cathedral City
and Rancho Mirage, through a lambing area. BLM and others are
attempting to rehabilitate the trail (J. Dugan, pers. comm. 1997).
The majority of sheep range is owned by State and Federal agencies
and managed for multiple human uses, especially recreational pursuits.
Four of eight ewe groups in the U.S. largely occur in the Anza Borrego
State Park, renowned as a premier hiking and camping destination. The
remaining four ewe groups largely occur within BLM's Santa Rosa
Mountains National Scenic Area, which is intended to expand
recreational opportunities through acquiring private lands for public
use and enjoyment. Coachella Valley commercial interests are
aggressively promoting and developing outdoor recreational industries
that capitalize on the scenic beauty of the Santa Rosa and San Jacinto
mountains. These industries and activities include jeep nature tours,
mountain biking, hiking, horseback riding, dog walking, camping, sight-
seeing, and other ecotourist forms of recreation in bighorn sheep
habitat that often use bighorn sheep images as advertising themes,
corporate and civic logos, etc. During the more temperate months of
October through April, the Coachella Valley attracts millions of
tourists and seasonal residents from across the Country and around the
world. The timing of maximum human use levels corresponds with
particularly sensitive periods in bighorn sheep life history, including
the lambing season, rut, and the late summer water stress period.
Publication of detailed critical habitat maps and descriptions, as
required with critical habitat designation, would make the location of
bighorn sheep more readily available to the general public and serve as
further advertisement for human uses in sensitive areas. Human activity
in bighorn sheep habitat has been identified as a threat (see Factor E
of ``Summary of Factors Affecting the Species''). An increase in human
activity, even when harm is not intended, would disrupt bighorn sheep
behavior and could cause abandonment of essential environments (e.g.,
lambing areas or watering holes) (Cowan and Geist 1971, Hicks and Elder
1979,
[[Page 13148]]
MacArthur et al. 1982, Hamilton et al. 1982, Sanchez et al. 1988).
Desert-dwelling bighorn sheep are inherently slow to recolonize vacant
habitat (Bleich et al. 1990). Thus, critical habitat designation would
increase the degree of threat to the Peninsular bighorn sheep and
result in harm to this distinct population segment rather than aid in
its conservation.
In addition, designation of critical habitat likely would not
benefit the conservation of this distinct population segment. Section
7(a)(2) of the Act requires Federal agencies, in consultation with the
Service, to ensure that any action authorized, funded or carried out by
such agency, does not jeopardize the continued existence of a federally
listed species or result in the destruction or adverse modification of
designated critical habitat. This latter requirement is the only
mandatory legal consequence of a critical habitat designation. Critical
habitat designation provides protection only on Federal lands or on
private or State lands when there is Federal involvement through
authorization or funding of, or participation in, a project or
activity. Almost half the habitat land area occupied by the Peninsular
bighorn sheep in the United States is owned and managed by the State of
California. The remainder is almost evenly divided between private and
Federal ownership (see BACKGROUND section). The protection afforded
under section 7 seldom extends onto State lands. Therefore, any
potential designation of critical habitat on State lands (which account
for about half of the U.S. range) would not be expected to benefit the
bighorn sheep. Similarly, a section 7 nexus would seldom occur on
private lands occupied by bighorn sheep because arid, upland habitats
typically do not support jurisdictional waters or wetlands regulated
under section 404 of the Clean Water Act.
Section 7 consultation is most likely to occur with the BLM
concerning minerals rights for mining, granting of rights-of-way,
recreational use permits, and management of grazing allotments. In
addition, consultation with the Corps through permit application review
under section 404 of the Clean Water Act may occur.
With about 75 percent of the U.S. range occurring on State and
private lands with a limited section 7 nexus, potential benefits
largely would be restricted to the remaining 25 percent of habitat that
occurs on Federal lands. However, designation of those areas necessary
for conservation (i.e., recovery) of the species cannot be accomplished
primarily on Federal lands. In addition, for recovery planning under
section 4 of the Act, designating critical habitat would not aid in
creating a Peninsular bighorn sheep management plan, addressing
transmission of diseases and establishing numerical population goals
for long-term survival of the species, nor directly affect areas not
designated as critical habitat. These types of issues will be addressed
through the recovery planning process, wherein the Service establishes
a framework for cooperation among key stakeholders and interest groups
to prepare and implement a recovery plan based on private and public
sector collaboration in defining and achieving recovery.
The Service acknowledges that critical habitat designation may
provide some benefits to a species by identifying areas important to a
species' conservation and calling attention to those areas in special
need of protection. A critical habitat designation contributes to
species conservation primarily by highlighting important habitat areas
and by describing the features within those areas that are essential to
the species. However, the Service is pursing alternative means to
achieve the objective of disseminating information on important habitat
areas by working directly with Federal and State land agencies and
private landowners to develop a coordinated management plan for the
Peninsular bighorn sheep.
In summary, there would be substantial risks to this bighorn sheep
distinct population segment by publicizing maps of areas of occupancy
and locations of habitats. Weighed against the fact that there would be
little or no additional benefit to the species, the Service finds that
designation of critical habitat for the Peninsular bighorn sheep is not
prudent.
The Service will continue in its efforts to obtain more information
on Peninsular bighorn sheep biology and ecology, including essential
habitat characteristics, current and historic distribution, disease
control, and other factors that would contribute to the conservation of
the species. The information resulting from these efforts will be used
to identify measures needed to achieve conservation of the species, as
defined under the Act. Such measures could include, but are not limited
to, development of a recovery plan, agency management plans, and
conservation agreements with the State, other Federal agencies, local
governments, and private landowners and organizations.
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, as amended, 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 Endangered Species Act are
codified at 50 CFR part 402. Section 7(a)(4) of the Act requires
Federal agencies to confer informally with the Service on any action
that is likely to jeopardize the continued existence of a proposed
species or result in destruction or adverse modification of proposed
critical habitat. If a species is subsequently 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 critical
habitat. If a Federal agency action may affect a listed species or its
critical habitat, the responsible Federal agency must enter into
consultation with the Service.
Federal agency actions that may require conference and/or
consultation as described in the preceding paragraph include those
within the jurisdiction of the Bureau of Indian Affairs, BLM, USFS,
Corps, and Department of Defense. The Peninsular bighorn sheep occurs
on private and State-owned land as well. Where the Peninsular bighorn
sheep occurs on private lands there is little or no Federal involvement
except where access is provided over Federal lands or permits are
required from the Corps under the Clean Water Act. The BLM and COE are
currently conferencing with the Service under section 7 of the Act to
address the impacts associated with granting rights-of-way for several
activities (e.g., recreational access).
The Act and implementing regulations found at 50 CFR 17.21 set
[[Page 13149]]
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 listed 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 agents of the Service
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, 17.23, and 17.32.
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 the policy of the Service, published in the Federal Register
on July 1, 1994 (59 FR 34272), to identify to the maximum extent
practical at the time a species is listed those activities that 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 that the Service believes could potentially harm the
Peninsular bighorn sheep and result in take include, but are not
limited to:
(1) Unauthorized trapping, capturing, handling or collecting of
Peninsular bighorn sheep. Research activities, where sheep are trapped
or captured, will require a permit under section 10(a)(1)(A) of the
Endangered Species Act.
(2) Unauthorized destruction or degradation of habitat through, but
not limited to, clearing vegetation, bulldozing terrain, and disturbing
natural drainage systems;
(3) Unauthorized destruction of habitat that will likely lead to
habitat fragmentation and isolation of ewe herds.
(4) Unauthorized livestock grazing that could result in
transmission of disease or habitat destruction.
Activities that the Service believes are unlikely to 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 this distinct population
segment that were collected prior to the date of publication in the
Federal Register of the final regulation adding this distinct
population segment to the list of endangered species;
(2) Accidental roadkills or injuries by vehicles conducted in
compliance with applicable laws, on designated public roads as
constructed upon the date of publication in the Federal Register of the
final regulation adding this distinct population segment to the list of
endangered species;
(3) Normal, authorized recreational activities in designated
campsites and on authorized trails.
(4) Lawful residential lawn maintenance activities including the
clearing of vegetation as a fire break around one's personal residence.
Questions regarding any specific activities should be directed to
the Service's Carlsbad Field 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 (503/231-6241; FAX 503/231-
6243)
Reasons for Effective Date
The Service is concerned that the issuance of the final rule for
the Peninsular bighorn sheep may result in the destruction of habitat
essential for maintaining the San Jacinto and Santa Rosa Mountain
herds. In addition, any delay in the effective date of this rule
provides an opportunity for habitat destruction in other portions of
its range in the United States. Habitat has been destroyed outside the
regulatory process at the Traditions Project in La Quinta. There is an
existing golf course development proposal to grade essential habitat in
the Palm Springs area. Because of the immediate threat posed by these
activities, the Service finds that good cause exists for this rule to
take effect immediately upon publication in accordance with 5 U.S.C.
Sec. 553(d)(3).
National Environmental Policy Act
The Fish and Wildlife Service has determined that an Environmental
Assessment, as defined under the authority of the National
Environmental Policy Act of 1969, need not be prepared in connection
with regulations adopted pursuant to section 4(a) of the Endangered
Species Act of 1973, as amended. A notice outlining the Service's
reasons for this determination was published in the Federal Register on
October 25, 1983 (48 FR 49244).
Required Determinations
This rule does not contain collections of information that require
approval by the Office of Management and Budget under 44 U.S.C. 3501 et
seq.
References Cited
A complete list of references cited in this rule is available upon
request from the Carlsbad Field Office of the U.S. Fish and Wildlife
Service (see ADDRESSES section).
Author: The primary author of this final rule is Arthur Davenport
of the Carlsbad Field Office (see ADDRESSES section).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
record-keeping requirements, Transportation.
Regulation Promulgation
Accordingly, the Service amends Part 17, Subchapter B of the
Chapter I, Title 50 of the Code of Federal Regulations, as set forth
below:
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) * * *
[[Page 13150]]
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Species Vertebrate
-------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mammals:
* * * * * * *
Bighorn sheep, (Peninsular Ranges Ovis canadensis..... U.S.A. (western U.S.A., Peninsular E 634 NA NA
population). conterminous Ranges of CA.
states), Canada
(southwest),
Mexico (north).
* * * * * * *
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Dated: March 6, 1998.
Jamie Rappaport Clark,
Director, Fish and Wildlife Service.
[FR Doc. 98-6998 Filed 3-17-98; 8:45 am]
BILLING CODE 4310-55-P
