Endangered and Threatened Wildlife and Plants; Endangered Status for the Peninsular Ranges Population Segment of the Desert Bighorn Sheep in Southern California

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