Endangered and Threatened Wildlife and Plants; Final Rule To List the Sierra Nevada Distinct Population Segment of the California Bighorn Sheep as Endangered

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AF59

Endangered and Threatened Wildlife and Plants; Final Rule To List

the Sierra Nevada Distinct Population Segment of the California Bighorn

Sheep as Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine

endangered status pursuant to the Endangered Species Act of 1973, as

amended (Act) for the Sierra Nevada distinct population segment of

California bighorn sheep (Ovis canadensis californiana). This species

occupies the Sierra Nevada of California, where it is known from five

disjunct subpopulations along the eastern escarpment of the Sierra

Nevada, and thought to total no more than 125 animals. All five

subpopulations are estimated to be very small and are threatened by

mountain lion (Felis concolor) predation, disease, naturally occurring

environmental events, and genetic problems associated with small

population size. We emergency listed this population segment of

California bighorn sheep on April 20, 1999. The emergency listing was

effective for 240 days. Immediately upon publication, this action

continues the protection provided by the temporary emergency listing.

DATES: This final rule is effective on January 3, 2000.

FOR FURTHER INFORMATION CONTACT: Carl Benz, at the U.S. Fish and

Wildlife Service, Ventura Fish and Wildlife Office, 2493 Portola Rd.

Suite B, Ventura, California 93003, (telephone 805/644-1766; facsimile

805/644-3958).

SUPPLEMENTARY INFORMATION:

Background

The bighorn sheep (Ovis canadensis) is a large mammal (family

Bovidae) originally described by Shaw in 1804 (Wilson and Reeder 1993).

Several subspecies of bighorn sheep have been recognized on the basis

of geography and differences in skull measurements (Cowan 1940;

Buechner 1960). These subspecies of bighorn sheep, as described in

these early works, include O. c. cremnobates (Peninsular bighorn

sheep), O. c. nelsoni (Nelson bighorn sheep), O. c. mexicana (Mexican

bighorn sheep), O. c. weemsi (Weems bighorn sheep), O. c. californiana

(California bighorn sheep), and O. c. canadensis (Rocky Mountain

bighorn sheep). However, recent genetic studies question the validity

of some of these subspecies and suggest a need to re-evaluate overall

bighorn sheep taxonomy. For example, Sierra Nevada bighorn sheep appear

to be more closely related to desert bighorn sheep than the O. c.

californiana found in British Columbia (Ramey 1991, 1993). Regardless,

the Sierra Nevada bighorn sheep meets our criteria for consideration as

a distinct vertebrate population segment (as discussed below) and is

treated as such in this final rule.

The historical range of the Sierra Nevada bighorn sheep (Ovis

canadensis californiana) includes the eastern slope of the Sierra

Nevada, and, for at least one subpopulation, a portion of the western

slope, from Sonora Pass in Mono County south to Walker Pass in Kern

County, a total distance of about 346 kilometers (km) (215 miles (mi))

(Jones 1950; Wehauser 1979, 1980). By the turn of the century, about 10

out of 20 subpopulations survived. The number dropped to five

subpopulations at mid-century, and down to two subpopulations in the

1970s, near Mount Baxter and Mount Williamson in Inyo County (Wehauser

1979). Currently, five subpopulations of Sierra Nevada bighorn sheep

occur, respectively, at Lee Vining Canyon, Wheeler Crest, Mount Baxter,

Mount Williamson, and Mount Langley in Mono and Inyo Counties, three of

which have been reintroduced using sheep obtained from the Mount Baxter

subpopulation from 1979 to 1986 (Wehausen et al. 1987).

The Sierra Nevada bighorn sheep is similar in appearance to other

desert associated bighorn sheep. The species' pelage shows a great deal

of color variation, ranging from almost white to fairly dark brown,

with a white rump. Males and females have permanent horns; the horns

are massive and coiled

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in males, and are smaller and not coiled in females (Jones 1950;

Buechner 1960). As the animals age, their horns become rough and

scarred, and will vary in color from yellowish-brown to dark brown. In

comparison to many other desert bighorn sheep, the horns of the Sierra

Nevada bighorn sheep are generally more divergent as they coil out from

the base (Wehausen 1983). Adult male sheep stand up to 1 meter (m) (3

feet (ft)) tall at the shoulder; males weigh up to 99 kilograms (kg)

(220 pounds (lbs)) and females 63 kg (140 lbs) (Buechner 1960).

The current and historical habitat of the Sierra Nevada bighorn

sheep is almost entirely on public land managed by the U.S. Forest

Service (FS), Bureau of Land Management (BLM), and National Park

Service (NPS). The Sierra Nevada mountain range is located along the

eastern boundary of California. Peaks vary in elevation from 1825 to

2425 m (6000 to 8000 ft) in the north, to over 4300 m (14,000 ft) in

the south adjacent to Owens Valley, and then drop rapidly in elevation

in the southern extreme end of the range (Wehausen 1980). Most

precipitation, in the form of snow, occurs from October through April

(Wehausen 1980).

Sierra Nevada bighorn sheep inhabit the alpine and subalpine zones

during the summer, using open slopes where the land is rough, rocky,

sparsely vegetated and characterized by steep slopes and canyons

(Wehausen 1980; Sierra Nevada Bighorn Sheep Interagency Advisory Group

(Advisory Group) 1997). Most of these sheep live between 3,050 and

4,270 m (10,000 and 14,000 ft) in elevation in summer (John Wehausen,

University of California, White Mountain Research Station, pers. comm.

1999). In winter, they occupy high, windswept ridges, or migrate to the

lower elevation sagebrush-steppe habitat as low as 1,460 m (4,800 ft)

to escape deep winter snows and find more nutritious forage. Bighorn

sheep tend to exhibit a preference for south-facing slopes in the

winter (Wehausen 1980). Lambing areas are on safe precipitous rocky

slopes. They prefer open terrain where they are better able to see

predators. For these reasons, forests and thick brush usually are

avoided if possible (J. Wehausen, pers. comm. 1999).

Bighorn sheep are primarily diurnal, and their daily activity shows

some predictable patterns that consists of feeding and resting periods

(Jones 1950). Bighorn sheep are primarily grazers; however, they may

browse woody vegetation when it is growing and very nutritious. They

are opportunistic feeders selecting the most nutritious diet from what

is available. Plants consumed include varying mixtures of grasses,

browse (shoots, twigs, and leaves of trees and shrubs), and herbaceous

plants, depending on season and location (Wehausen 1980). In a study of

the Mount Baxter and Mount Williamson subpopulations, Wehausen (1980)

found that grass, mainly Stipa speciosa (perennial needlegrass), is the

primary diet item in winter. As spring green-up progresses, the bighorn

sheep shift from grass to a more varied browse diet, which includes

Ephedra viridis (Mormon tea), Eriogonum fasciculatum (California

buckwheat), and Purshia species (bitterbrush).

Sierra Nevada bighorn sheep are gregarious, with group size and

composition varying with gender and from season to season. Spatial

segregation of males and females occurs outside the mating season, with

males more than 2 years old living apart from females and younger males

for most of the year (Jones 1950; Cowan and Geist 1971; Wehausen 1980).

Ewes generally remain in the same band into which they were born (Cowan

and Geist 1971). During the winter, Sierra Nevada bighorn sheep

concentrate in those areas suitable for wintering, preferably Great

Basin habitat (sagebrush-steppe) at the very base of the eastern

escarpment. Subpopulation size can number more than 100 sheep,

including rams (this was observed at a time when the population size

was larger than it is currently) (J. Wehausen, pers. comm. 1999).

Breeding takes place in the fall, generally in November (Cowan and

Geist 1971). Single births are the norm for North American wild sheep,

but twinning is known to occur (Wehausen 1980). Gestation is about 6

months (Cowan and Geist 1971).

Lambing occurs between late April to early July, with most lambs

born in May or June (Wehausen 1980, 1996). Ewes with newborn lambs live

solitarily for a short period before joining nursery groups that

average about six sheep. Ewes and lambs frequently occupy steep terrain

that provides a diversity of slopes and exposures for escape cover.

Lambs are precocious, and within a day or so, climb almost as well as

the ewes. Lambs are able to eat vegetation within 2 weeks of their

birth and are weaned between 1 and 7 months of age. By their second

spring, they are independent of their mothers. Female lambs stay with

ewes indefinitely and may attain sexual maturity during the second year

of life. Male lambs, depending upon physical condition, may also attain

sexual maturity during the second year of life (Cowan and Geist 1971).

Average lifespan is 9 to 11 years in both sexes, though some rams are

known to have lived to 12 to 14 years old (Cowan and Geist 1971;

Wehausen 1980).

Distinct Vertebrate Population Segment

Recent analyses of bighorn sheep genetics and morphometrics (e.g.,

size and shape of body parts) suggest reevaluation of the taxonomy of

Sierra Nevada bighorn sheep (Ovis canadensis californiana) is necessary

(Ramey 1991, 1993, 1995; Wehausen and Ramey 1993; Wehausen and Ramey

2000 (in review)). A recent analysis of the taxonomy of bighorn sheep

using morphometrics and genetics failed to support the current taxonomy

(Ramey 1993, 1995; Wehausen and Ramey 1993; Wehausen and Ramey 2000 (in

review)). This and other research (Ramey 1993) supports taxonomic

distinction of the Sierra Nevada bighorn sheep relative to other nearby

regions.

The biological evidence supports recognition of Sierra Nevada

bighorn sheep as a distinct vertebrate population segment for purposes

of listing, as defined in our February 7, 1996, Policy Regarding the

Recognition of Distinct Vertebrate Population Segments (61 FR 4722).

The definition of ``species'' in section 3(16) of the Act includes

``any distinct population segment of any species of vertebrate fish or

wildlife which interbreeds when mature.'' For a population to be listed

under the Act as a distinct vertebrate population segment, three

elements are considered--1) the discreteness of the population segment

in relation to the remainder of the species to which it belongs; 2) the

significance of the population segment to the species to which it

belongs; and 3) the population segment's conservation status in

relation to the Act's standards for listing (i.e., is the population

segment, when treated as if it were a species, endangered or

threatened?) (61 FR 4722).

The distinct population segment (DPS) of bighorn sheep in the

Sierra Nevada is discrete in relation to the remainder of the species

as a whole. This DPS is geographically isolated and separate from other

California bighorn sheep populations. There is no mixing of Sierra

Nevada bighorn sheep with other bighorn sheep subspecies. This is

supported by an evaluation of the population's genetic variability and

morphometric analysis of skull and horn variation (Ramey 1993, 1995;

Wehausen and Ramey 1993, 1994; Wehausen and Ramey 2000 (in review)).

Sierra Nevada bighorn sheep males have particularly wide skulls but

small horns, compared to other subspecies of bighorn sheep (Wehausen

and Ramey 2000 (in review)). Also, Sierra Nevada bighorn

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sheep have a unique mitochondrial DNA pattern, different from other

bighorn sheep populations (Ramey 1993, 1995). Mitochondrial DNA are

genes that are inherited maternally in animals, and so are useful as

genetic markers when researching population genetic questions (Ramey

1993). Researchers suggest that all other populations of Ovis

canadensis californiana be reassigned to other subspecies, leaving O.

c. californiana (i.e., the subspecies found within the DPS that is the

subject of this rule) only in the central and southern Sierra Nevada

(Ramey 1993, 1995; Wehausen and Ramey 1993, 1994; Wehausen and Ramey

2000 (in review)).

The Sierra Nevada bighorn sheep DPS is biologically and

ecologically significant to the species in that it constitutes the only

population of California bighorn sheep inhabiting the Sierra Nevada.

This DPS extends from Sonora Pass to Walker Pass, spanning

approximately 346 km (215 mi) of contiguous suitable habitat in the

United States. It is likely that there was gene flow in the past

between bighorn sheep populations in the Sierra Nevada Mountains (Ovis

canadensis californiana) and the White-Inyo Mountains (O. c. nelsoni),

which are separated by Owens Valley (Ramey 1993, 1995). Genetic

research indicates, however, that there are differences between the

bighorn sheep populations in the Sierra Nevada and those in the White-

Inyo Mountains (Ramey 1991, 1993, 1995). Any dispersal that occurred

between the two mountain ranges was likely by males since female

bighorn sheep have a much lower rate of dispersal, probably due to the

females not wanting to expose themselves or their lambs to predation by

crossing the open terrain of Owens Valley (Ramey 1995). Movement

between the populations apparently no longer occurs due to artificial

barriers such as canals, highways, and fences (Jones 1950; Ramey 1993,

1995). Sierra Nevada bighorn sheep also have different morphological

features, and they are genetically different from other bighorn

populations (Ramey 1991, 1993, 1995; Wehausen and Ramey 1993, 1994;

Wehausen and Ramey 2000 (in review)). The loss of Sierra Nevada bighorn

sheep would result in the total extirpation of bighorn sheep from the

Sierra Nevada in California. The loss of Sierra Nevada bighorn sheep in

the Sierra Nevada mountain range would also create a significant gap in

bighorn sheep population distribution. The Sierra Nevada bighorn sheep

are the most northern population of bighorn in California, with the

closest population to the north being at Hart Mountain in Oregon

(Jinelle, O'Connor, Lassen National Forest, pers. comm. 1999), and the

closest population to the south and east being the White-Inyo Mountain

bighorn populations. The loss of the Sierra Nevada bighorn sheep would

further isolate bighorn sheep populations in Oregon from those in

southern California.

Status and Distribution

Historically, Sierra Nevada bighorn sheep populations occurred

along and east of the Sierra Nevada crest from Sonora Pass (Mono

County) south to Walker Pass (Olancha Peak) (Kern County) (Jones 1950;

Wehausen 1979). Sheep apparently occurred wherever appropriate rocky

terrain and winter range existed. With some exceptions, most of the

populations wintered on the east side of the Sierra Nevada and spent

summers near the crest (Wehausen 1979).

Subpopulations of Sierra Nevada bighorn sheep probably began

declining with the influx of gold miners to the Sierra Nevada in the

mid-1880s, and those losses have continued through the 1900s (Wehausen

1988). By the 1970s, only two subpopulations of Sierra Nevada bighorn

sheep, those near Mount Baxter and Mount Williamson in Inyo County, are

known to have survived (Wehausen 1979). Specific causes for the

declines are unknown. Market hunting may have been a contributing

factor as evidenced by menus from historic mining towns such as Bodie,

which included bighorn sheep (Advisory Group 1997). However, with the

introduction of domestic sheep in the 1860s and 1870s, wild sheep are

known to have died in large numbers in several areas from disease

contracted from domestic livestock (Jones 1950; Buechner 1960). Large

numbers of domestic sheep were grazed seasonally in the Owens Valley

and Sierra Nevada prior to the turn of the century (Wehausen 1988), and

disease is believed to be the factor most responsible for the

disappearance of bighorn subpopulations in the Sierra Nevada. Jones

(1950) suggested that scabies were responsible for a die-off in the

1870s on the Great Western Divide. Experiments have confirmed that

bacterial pneumonia (teurellaecies), carried normally by domestic

sheep, can be fatal to bighorn sheep (Foreyt and Jessup 1982).

In 1971, the Sierra Nevada bighorn sheep was listed as threatened

under the 1970 California Endangered Species Act (California Department

of Fish and Game 1974, as cited by Advisory Group 1997; California

Department of Fish and Game 1999). This classification led to the

development and implementation of a State recovery plan, which has two

main goals: (1) create at least two additional populations numbering at

least 100 sheep that could serve as reintroduction stock in the event

of a catastrophic decline in the Mount Baxter subpopulation, and (2)

re-establish the sheep throughout historic ranges in the Sierra Nevada

where biologically and politically feasible (Advisory Group 1997).

Intensive field studies began in 1975 which provided accurate census

data for the two surviving subpopulations. In 1979, re-introductions of

sheep into historical habitat (also known as the restoration program)

began and was conducted by several Federal and State agencies from 1979

to 1988 (Advisory Group 1997). By 1979, only 220 sheep were known to

exist in the Mount Baxter subpopulation, and 30 in the Mount Williamson

subpopulation (Wehausen 1979). Sheep were obtained from the Mount

Baxter subpopulation and transplanted to three historic locations,

which were Lee Vining Canyon, Wheeler Crest, and Mount Langley

(Wehausen 1996; Advisory Group 1997). Consequently, Sierra Nevada

bighorn sheep now occur in five subpopulations in Mono and Inyo

Counties : Lee Vining Canyon, Wheeler Crest, Mount Baxter, Mount

Williamson, and Mount Langley. The Sierra Nevada bighorn sheep

population reached a high of about 310 in 1985-86, but subsequent

population surveys have documented a declining trend (J. Wehausen,

pers. comm. 1999). Currently, it is estimated that the total Sierra

Nevada bighorn sheep population is 125 animals (J. Wehausen, pers.

comm. 1999).

The following table best represents the total Sierra Nevada bighorn

sheep population over various time periods. These totals represent the

numbers of sheep emerging from winter in each of these years, and best

documents the status of the population by incorporating winter

mortality, especially of lambs born the previous year. These totals are

not absolute values; numbers have been rounded to the nearest five (J.

Wehausen, pers. comm. 1999). The continuing decline of the Sierra

Nevada bighorn sheep has been attributed to a combination of the direct

and indirect effects of predation (Wehausen 1996).

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Table 1.--Sierra Nevada Bighorn Sheep Population Numbers, by Year (J.

Wehausen, Pers. Comm. 1999)

------------------------------------------------------------------------

Number of

Year populations Total sheep

------------------------------------------------------------------------

1978.......................................... 2 250

1985.......................................... 4 310

1995.......................................... 5 100

1996.......................................... 5 110

1997.......................................... 5 130

1998.......................................... 5 100

1999.......................................... 5 *125

------------------------------------------------------------------------

*Note that the difference in population size between 1998 and 1999 is

based on (1) a small band of bighorn sheep were located in Sand

Mountain (Mount Baxter subpopulation), and (2) approximately 15 lambs

were born to the Wheeler Crest subpopulation in 1999.

Previous Federal Action

In our September 18, 1985, Notice of Review, we designated the

Sierra Nevada bighorn sheep as a category 2 candidate and solicited

status information (50 FR 37958). Category 2 candidate species included

taxa for which we had information indicating that proposing to list as

endangered or threatened was possibly appropriate, but for which

sufficient data on biological vulnerability and threats were not

currently available to support a proposed rule. Category 1 candidates

were those species for which we had sufficient information on file to

support issuance of proposed listing rules. In our January 6, 1989 (54

FR 554), and November 21, 1991 (56 FR 58804), Notices of Review, we

retained the Sierra Nevada bighorn sheep in category 2. Beginning with

our February 28, 1996, Notice of Review (61 FR 235), we discontinued

the designation of multiple categories of candidates, and we now

consider only species that meet the definition of former category 1 as

candidates for listing. At that point, the Sierra Nevada bighorn sheep

was not identified as a candidate.

On February 12, 1999, we received a petition dated February 9,

1999, from the Friends of the Inyo, National Parks and Conservation

Association, Natural Resources Defense Council, Sierra Nevada Bighorn

Sheep Foundation, and The Wilderness Society, to list the Sierra Nevada

bighorn sheep as endangered throughout its range, with a special

request for an emergency listing under the Act. The petition provided

information on the species' classification and biology, past and

present conservation efforts, historic and current distribution,

population trends, and threats facing this species, including small

population effects, disease, predation and habitat curtailment, fire,

and inadequacy of existing regulations.

On April 20, 1999, we published an emergency rule to list the

Sierra Nevada distinct population segment of California bighorn sheep

as endangered (64 FR 19300), as well as a proposed rule (64 FR 19333)

to list the species as endangered on that same date.

The processing of this final rule conforms with our listing

priority guidance published in the Federal Register on October 22, 1999

(64 FR 57114). Highest priority is processing emergency listing rules

for any species determined to face a significant and imminent risk to

its well being (Priority 1). Second priority (Priority 2) is processing

final determinations on proposed additions to the Federal lists of

endangered and threatened wildlife and plants. Third priority is

processing new proposals to add species to the lists. The processing of

administrative petition findings (petitions filed under section 4 of

the Act) is fourth priority. The processing of critical habitat

determinations (prudency and determinability decisions) and proposed

and final designations of critical habitat will no longer be subject to

prioritization under the listing priority guidance. This final rule is

a Priority 2 action and is being completed in accordance with the

current listing priority guidance. We have updated this rule to reflect

any changes in information concerning distribution, status, and threats

since publication of the proposed rule.

Summary of Comments and Recommendations

In the April 20, 1999, proposed rule (64 FR 19333), we requested

all interested parties to submit factual reports or information that

might contribute to development of a final rule. A 60-day comment

period closed on June 21, 1999. We contacted appropriate Federal

agencies, State agencies, county and city governments, scientific

organizations, and other interested parties and requested comments. We

published public notices of the proposed rule in the Inyo Register in

Inyo County and Fresno Bee in Fresno County on May 8, 1999, and in the

Mammoth Times in Mono County on May 13, 1999, which invited general

public comment. We did not receive any requests for a public hearing.

We re-opened the comment period on September 30, 1999, at the request

of the Foundation for North American Wild Sheep and to solicit a peer

review of the proposed rule. The comment period ended on October 15,

1999.

During the public comment period, we received written comments from

39 individuals or organizations, with one commenter submitting comments

during both comment periods. All but two commenters supported the

listing of the Sierra Nevada bighorn sheep. One commenter sent a letter

refuting some information presented to us by another commenter. Issues,

and our response to each, are summarized below.

Issue 1: One commenter requested that we recognize a long-term

ecosystem approach for recovery that includes healthy predator/prey

relations.

Our Response: We agree that recovery should be based on restoring,

to the greatest extent possible, the ecosystem such that the natural

dynamics of predator/prey relationships function with minimal or no

human intervention. We recognize this in the rule, and the actual goals

and tasks necessary to achieve recovery of the species will be

discussed in detail in the Sierra Nevada bighorn sheep recovery plan.

Issue 2: Two commenters asked that we designate critical habitat

for the Sierra Nevada bighorn sheep.

Our Response: In the emergency rule, we indicated that designation

of critical habitat was not determinable for the Sierra Nevada bighorn

sheep due to a lack of information sufficient to perform the required

analysis of impacts of the designation. As discussed below in the

critical habitat section, we have re-examined the question of whether

critical habitat is not determinable and have determined that there is

sufficient information to do the required analysis and that designation

of critical habitat for the species is prudent.

As explained in detail in the Final Listing Priority Guidance for

FY 2000 (64 FR 57114), our listing budget is currently insufficient to

allow us to immediately complete all of the listing actions required by

the Act. We will defer critical habitat designation for the Sierra

Nevada bighorn sheep in order to allow us to concentrate our limited

resources on higher priority critical habitat (including court-ordered

designations) and other listing actions, while allowing us to put in

place protections needed for the conservation of the Sierra Nevada

bighorn sheep without further delay.

We plan to employ a priority system for deciding which outstanding

critical habitat designations should be addressed first. We will focus

our efforts on those designations that will provide the most

conservation benefit, taking into consideration the efficacy of

critical habitat designation in addressing the threats to the species,

and the magnitude and immediacy of those

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threats. We will develop a proposal to designate critical habitat for

the Sierra Nevada bighorn sheep as soon as feasible, considering our

workload priorities.

Issue 3: Several commenters stated that we should require other

Federal agencies to utilize their authorities to eliminate grazing

permits on Federal land, and initiate formal consultation under section

7 of the Act.

Our Response: Upon emergency listing of the Sierra Nevada bighorn

sheep, we notified all Federal agencies of this listing and their

responsibilities under section 7 of the Act to consult with us on

actions that may affect the Sierra Nevada bighorn sheep. During the

emergency listing period, the FS consulted on their actions for

permitting domestic sheep grazing, conducting prescribed burns to

enhance bighorn sheep winter habitat, as well as removing wreckage from

a crashed airplane in bighorn sheep habitat. With the final listing of

this species, we will continue to expect Federal agencies to comply

with section 7 of the Act and consult with us, and we will work with

these Federal agencies, as well as State agencies, to reduce threats to

the species.

Issue 4: One commenter requested that we clarify our policies and

procedures on deterrence and removal of Sierra Nevada bighorn sheep

predators, and that the final rule should include clear guidelines for

how we will manage predators.

Our Response: In accordance with our Interagency Cooperative Policy

on Recovery Plan Participation and Implementation Under the Endangered

Species Act (July 1, 1994; 59 FR 34272), and our recovery guidelines,

we will develop a recovery plan that is ecosystem-based, and clearly

identify quantifiable recovery criteria and goals, and we will clearly

identify those management actions necessary to achieve recovery of the

species.

Issue 5: One commenter stated that we should conduct studies to

examine biological effects of differential removal of mountain lions on

the Sierra Nevada bighorn sheep.

Our Response: We agree that this should be an important goal of

recovery efforts. In addition to specific management actions, specific

research aimed at better understanding the species and ecosystem (e.g.,

predator/prey relationships, population demography) will be identified

in the recovery plan.

Issue 6: One commenter stated that Federal listing is no longer

warranted because: 1) Assembly Bill (A. B.) 560 was recently signed

into State law providing the California Department of Fish and Game

(CDFG) to remove or take mountain lions that are perceived to be a

threat to the sheep; (2) CDFG was appropriated State funds for the

recovery of the Sierra Nevada bighorn sheep; and (3) Federal agencies

and the Los Angeles Department of Water and Power have demonstrated

good faith efforts at reducing the likelihood of contact between

domestic sheep and the Sierra Nevada bighorn sheep.

Our Response: We disagree. In evaluating the need for listing, we

must look at a variety of factors affecting the species. This DPS of

California bighorn sheep meets the definition of an endangered species

based on several factors, only one of which is mountain lion predation.

We agree that the passage and signing into law of A. B. 560 provides an

additional ability to protect the Sierra Nevada bighorn sheep from

mountain lions, as well as funds for recovery efforts. However, while

this law will reduce the threat from mountain lion predation, it will

not completely eliminate it. In addition, this legislation was enacted

very recently, in September of 1999, and little time has passed to

allow an evaluation of its effectiveness. We also agree that the CDFG

was appropriated funds for the recovery of the species, however, these

funds do not mean that all of the threats to the species have been

removed such that listing is unnecessary. We also agree that the

Federal agencies and Los Angeles Department of Water and Power have

demonstrated good faith efforts at reducing the likelihood of contact

between domestic and wild sheep. However, these efforts have come about

due to the emergency listing and the subsequent requirement that

Federal agencies must consult with us to ensure that their actions do

not jeopardize the continued existence of the species.

Peer Review

In accordance with our July 1, 1994, Interagency Cooperative Policy

for Peer Review in Endangered Species Act Activities (59 FR 34270), we

solicited the expert opinions of three independent specialists

regarding pertinent scientific or commercial data and assumptions

relating to bighorn sheep ecology, predator/prey relationships, and

disease considered in the proposed rule (64 FR 19333). The purpose of

such a review is to ensure that listing decisions are based on

scientifically sound data, assumptions, and analyses, including input

from appropriate experts. All three reviewers sent us a letter during

the public comment period supporting the listing of the Sierra Nevada

bighorn sheep. One of the three provided additional documentation on

disease threats to bighorn sheep from domestic sheep; another provided

conservation and recovery recommendations. Information and suggestions

provided by the reviewers were considered in developing this final

rule, and incorporated where applicable.

Summary of Factors Affecting the Species

After a thorough review and consideration of all information

available, we have determined that the Sierra Nevada bighorn sheep DPS

warrants classification as an endangered species. We followed

procedures found at section 4 of the Act and regulations (50 CFR part

424) issued to implement the listing provisions of the Act. We

determine a species to be endangered or threatened due to one or more

of the five factors described in section 4(a)(1). These factors, and

their application to the Sierra Nevada bighorn sheep DPS (Ovis

canadensis californiana), are as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment

of Its Habitat or Range

Habitat throughout the historic range of Sierra Nevada bighorn

sheep remains essentially intact; the habitat is neither fragmented nor

degraded. However, by 1900, about half of the Sierra Nevada bighorn

sheep populations were lost, most likely because of the introduction of

diseases by domestic livestock, and illegal hunting (Advisory Group

1997). Beginning in 1979, animals from the Mount Baxter subpopulation

were translocated to reestablish subpopulations in Lee Vining Canyon,

Wheeler Crest, and Mount Langley in Mono and Inyo Counties in order to

re-establish the species in historical habitat (Advisory Group 1997).

Currently, Sierra Nevada bighorn sheep are limited to five

subpopulations. Almost all of the historical and current habitat is

administered by either the FS, BLM, or NPS, though there are some small

parcels of inholdings within the species' range which are owned by the

Los Angeles Department of Water and Power. Also, there are some

patented mining claims in bighorn sheep habitat, but the total acreage

is small.

B. Overutilization for Commercial, Recreational, Scientific, or

Educational Purposes

During the period of the California gold rush (starting about

1849), hunting to supply food for mining towns may have played a role

in the decline of the population (Wehausen 1988). Besides

[[Page 25]]

being sought as food, Sierra Nevada bighorn sheep were also killed by

sheepmen who considered the species competition for forage with

domestic sheep. The decimation of several wildlife species in the late

1800s prompted California to pass legislation providing protection to

several species including bighorn sheep (Jones 1950; Wehausen 1979).

Commercial and recreational hunting of Sierra Nevada bighorn sheep

is not permitted under State law. There is no evidence that other

commercial, recreational, scientific, or educational activities are

currently a threat. Poaching does not appear to be a problem at this

time.

C. Disease or Predation

Disease is believed to have been the major contributing factor

responsible for the precipitous decline of Sierra Nevada bighorn sheep

starting in the late 1800s (Foreyt and Jessup 1982).

Bighorn sheep are host to a number of internal and external

parasites, including ticks, lice, mites, tapeworms, roundworms, and

lungworms. Most of the time, parasites are present in relatively low

numbers and have little effect on individual sheep and populations

(Cowan and Geist 1971).

Cattle were first introduced into the Sierra Nevada in 1860s but

were replaced with domestic sheep that could graze more extensively

over the rugged terrain (Wehausen et al. 1987; Wehausen 1988). Large

numbers of domestic sheep were grazed seasonally in the Sierra Nevada

prior to the turn of the century, and the domestic sheep would use the

same ranges as the wild sheep, occasionally coming into direct contact

with them. Both domestic sheep and cattle can act as disease

reservoirs. Scabies, most likely contracted from domestic sheep, caused

a major decline of bighorn sheep in California in the 1870s to the

1890s, and caused catastrophic die-offs in other parts of their range

(Buechner 1960). A die-off of bighorn sheep in the 1870s on the Great

Western Divide (Mineral King area of Sequoia National Park) was

attributed to scabies, presumably contracted from domestic sheep (Jones

1950).

Die-offs from pneumonia contracted from domestic sheep is another

important cause of losses. In 1988, a strain of pneumonia, apparently

contracted from domestic sheep, wiped out the reintroduced South Warner

Mountains herd of bighorn sheep (David A. Jessup, CDFG, in litt. 1999).

These bighorn sheep, which included Sierra Nevada bighorn sheep, died

of fibrinopurulent bronchopneumonia, caused by a virulent strain of

Pasteurella species bacteria. Domestic sheep had been observed running

with the bighorn prior to this outbreak (D. Jessup, in litt. 1999).

Native bighorn sheep cannot tolerate strains of respiratory bacteria

such as Pasteurella species, carried normally by domestic sheep, and

close contact with domestic animals results in transmission of disease

and subsequent deaths of the exposed animals (Foreyt and Jessup 1982).

Similar die-offs of bighorn sheep populations have occurred elsewhere,

such as in Lava Beds National Monument, California, and in Gerlach,

Nevada, where it was documented that domestic sheep came into contact

with wild sheep (Foreyt and Jessup 1982; D.A. Jessup, in litt. 1999).

Bighorn sheep can also develop pneumonia independent of contact

with domestic sheep. Lungworms of the genus Protostrongylus are often

an important contributor to the pneumonia disease process in some

situations (J. Wehausen, pers. comm. 1999). Lungworms are carried by an

intermediate host snail, which is ingested by a sheep as it is grazing.

Lungworm often exists in a population without causing a problem.

However, if the sheep are stressed in some way, they may develop

bacterial pneumonia, which is complicated by lungworm infestation.

Bacterial pneumonia is usually a sign of weakness caused by some other

agent such as a virus, parasite, poor nutrition, predation, human

disturbance, or environmental or behavioral stress that lowers the

animal's resistence to disease (Wehausen 1979; Foreyt and Jessup 1982).

Bighorn sheep in the Sierra Nevada carry Protostrongylus species

(lungworms), but the parasite loads have been low, and there has been

no evidence of any clinical signs of disease or disease transmission

(Wehausen 1979; Richard Perloff, Inyo National Forest, pers. comm.

1999).

Currently, domestic sheep grazing allotments are permitted by the

FS in areas adjacent to Sierra Nevada bighorn sheep subpopulations.

Domestic sheep occasionally escape the allotments and wander into

bighorn sheep areas, sometimes coming into direct contact with bighorn

sheep (Advisory Group 1997). For example, in 1995, 22 domestic sheep

that were permitted on FS land wandered away from the main band and

were later found in Yosemite National Park, after crossing through

occupied bighorn sheep habitat (Advisory Group 1997; Bonny Pritchard,

Inyo National Forest, pers. comm. 1999; R. Perloff, pers. comm. 1999).

Other stray domestic sheep, in smaller numbers, have been known to

wander up the road in Lee Vining Canyon into bighorn sheep habitat (B.

Pritchard, pers. comm. 1999). Based on available information, and given

the susceptibility of bighorn sheep to introduced pathogens, disease

will continue to pose a significant and underlying threat to the

survival of Sierra Nevada bighorn sheep until the potential for contact

with domestic sheep is eliminated.

Predators such as coyote (Canis latrans), bobcat (Lynx rufus),

mountain lion, gray fox (Urocyon cinereoargenteus), golden eagle

(Aquila chrysaetos), and free-roaming domestic dogs prey upon bighorn

sheep (Jones 1950; Cowan and Geist 1971). Predation generally has an

insignificant effect except on small populations such as the Sierra

Nevada bighorn sheep. Coyotes are the most abundant large predator

sympatric (occurring in the same area) with bighorn sheep populations

(Bleich 1999), and are known to have killed young Sierra Nevada bighorn

sheep (Vernon Bleich, CDFG, pers. comm. 1999). In the late 1980s,

mountain lion predation of Sierra Nevada bighorn sheep increased

throughout their range (Wehausen 1996). This trend has continued into

the 1990s, as evidenced by Table 1.

Predation by mountain lions probably was a natural occurrence and

part of the natural balance of this ecosystem. From 1907 to 1963, the

State provided a bounty on mountain lions; the State also hired

professional lion hunters for many years. The bounty most likely kept

the mountain lion population reduced such that bighorn sheep predation

was rare and insignificant. Between 1963 and 1968, mountain lions were

managed as a nongame and nonprotected mammal, and take was not

regulated. From 1969 to 1972, lions were re-classified as game animals.

A moratorium on mountain lion hunting began in 1972 and lion numbers

likely increased. In 1986, the species was again classified as a game

animal, but CDFG hunting recommendations were challenged in court in

1987 and 1988 (Tories et al. 1996). In 1990, a State-wide ballot

initiative (Proposition 117) passed into law prohibiting the killing of

mountain lions except if humans, or their pets or livestock are

threatened. Another ballot measure, Proposition 197, which would have

modified current law regarding mountain lion management failed to pass

in 1996, largely because of the public's concern that the change may

allow mountain lion hunting (Tories et al. 1996). With the removal of

the ability to control the mountain lion population, lion predation

became a significant

[[Page 26]]

limiting factor on Sierra Nevada bighorn sheep.

The increased presence of mountain lions appears to have changed

Sierra Nevada bighorn sheep winter habitat use patterns. Wehausen

(1996) looked at mountain lion predation in two bighorn sheep

subpopulations, one in the Granite Mountains of the eastern Mojave

Desert, and the other in the Mount Baxter subpopulation in the Sierra

Nevada. He found that the lions reduced the subpopulation in the

Granite Mountains to eight ewes between 1989 and 1991, and held it at

that level for 3 years, after which lion predation decreased and the

bighorn sheep subpopulation increased at 15 percent per year for 3

years. All the mortality in that subpopulation was attributed to

mountain lion predation. The Mount Baxter bighorn sheep subpopulation

abandoned its winter ranges, presumably due to mountain lion predation.

Forty-nine sheep were killed by lions on their winter range between

1976 and 1988 out of an average subpopulation size of 127 sheep. These

mortalities from mountain lion predation represented 80 percent of all

mortality on the winter range, and 71 percent for all ranges used.

Evidence also indicates that many of the bighorn sheep killed were

prime-aged animals (J. Wehausen, pers. comm. 1999).

The bighorn sheep on Mount Baxter may have moved to higher

elevations to evade lions. By avoiding the lower terrain and

consequently the higher quality forage present during the spring, sheep

emerged from the winter months in poorer condition. Consequences from

the change in habitat use resulted in a decline in the Baxter

subpopulation due to decreased lamb survival, because lambs were born

later and died in higher elevations during the winter. This may have

also been the case with the Lee Vining subpopulation decline; bighorn

sheep may have run out of fat reserves at a time when they should have

been replenishing their reserves with highly nutritious forage from low

elevation winter ranges. We believe that because of the winter habitat

shift by the bighorn sheep, the Mount Baxter subpopulation has declined

significantly. With the large decline of bighorn sheep on Mount Baxter,

the total population of Sierra Nevada bighorn sheep has now dropped

below what existed during implementation of the restoration program

between 1979 and 1988 (Wehausen 1996; Advisory Group 1997), which

transplanted sheep back into historical habitat. In a 1996 survey on

Mount Williamson, there was no evidence of groups of sheep, and this

subpopulation was the last one found using its low-elevation winter

range in 1986. Mountain lion predation may have led to the extirpation

of this subpopulation, one of the last two native subpopulations of

Sierra Nevada bighorn sheep (Wehausen 1996; J. Wehausen, pers. comm.

1999).

In 1998 and 1999, few mountain lions were documented using the

Wheeler Crest subpopulation winter habitat. As a result, this

subpopulation returned to its winter range, and 15 lambs were born to

the subpopulation in 1998 and again in 1999. The Langley subpopulation

continues to avoid its winter habitat, presumably due to the presence

of mountain lions there. As a result, the ewes were in very poor

condition in the spring and had not recovered to good condition by

August 1999. One sheep was documented to have been killed by a mountain

lion in 1999 (J. Wehausen, pers. comm. 1999).

On September 16, 1999, California enacted legislation (Assembly

Bill 560) amending Proposition 117 allowing the CDFG to remove or take

mountain lions that are perceived to be a threat to the survival of any

threatened, endangered or fully protected sheep species (Diana Craig,

FS, in litt. 1999; Office of the Governor 1999). Passage of this bill

will help manage mountain lion predation on Sierra Nevada bighorn

sheep, but likely will not eliminate this threat. The authority of the

State to manage mountain lion predation under this law is limited and

has not yet been fully tested. For example, the law allows the State to

take mountain lions perceived to be an immediate threat to protected

bighorn sheep. However, it is not clear that this authority extends to

removing lions whose presence at lower elevation, winter sheep habitat

precludes normal, seasonal, bighorn sheep migration patterns. The

ability to migrate to these lower elevation areas for winter use is

considered crucial to improving the productivity rate of bighorn sheep

populations.

The Sierra Nevada bighorn sheep restoration program, implemented

between 1979 to 1988 to reintroduce the sheep into historical habitat,

used the Mount Baxter subpopulation as the source of reintroduction

stock. The three reintroduced subpopulations at Lee Vining Canyon,

Wheeler Crest, and Mount Langley all suffered from mountain lion

predation shortly after translocation of sheep (Wehausen 1996). The Lee

Vining Canyon subpopulation lost a number of sheep to mountain lion

predation, threatening the success of the reintroduction effort (Chow

1991, cited by Wehausen (1996)). The subpopulation was supplemented

with additional sheep, and the State removed one mountain lion each

year for 3 years, which helped reverse the decline of this

subpopulation (Bleich et al. 1991 and Chow 1991, cited by Wehausen

(1996)). Also, because domestic sheep are preyed upon by mountain

lions, livestock operators who have a Federal permit to graze their

sheep on FS land can get a depredation permit from the State, and have

the U.S. Department of Agriculture, Wildlife Services, remove the

mountain lion. The Lee Vining Canyon subpopulation occurs in the

general area where domestic sheep are permitted, and has benefitted

from the removal of mountain lions that were preying on domestic sheep

(B. Pritchard, pers. comm. 1999). However, this subpopulation has

continued to decline, and in 1999, only one reproductive ewe remains

(J. Wehausen, pers. comm. 1999).

D. The Inadequacy of Existing Regulatory Mechanisms

In response to a very rapid decline in population numbers, in 1876

the State legislature amended an 1872 law that provided seasonal

protection for elk, deer and pronghorn to include all bighorn sheep.

Two years later, this law was amended, establishing a 4-year moratorium

on the taking of any pronghorn, elk, mountain sheep or female deer. In

1882, this moratorium was extended indefinitely for bighorn sheep

(Wehausen et al. 1987). In 1971, California listed the California

bighorn sheep as ``rare.'' The designation was changed to

``threatened'' in 1984 to standardize the terminology of the amended

California Endangered Species Act (CESA) (Advisory Group 1997). The

California Fish and Game Commission upgraded the species' status to

``endangered'' in 1999 (Mammoth Times 1999; San Francisco Chronicle

1999; CDFG 1999). Pursuant to the California Fish and Game Code and the

CESA, it is unlawful to import or export, take, possess, purchase, or

sell any species or part or product of any species listed as endangered

or threatened. Permits may be authorized for certain scientific,

educational, or management purposes, and to allow take incident to

otherwise lawful activities.

The policy of the State of California is to protect and preserve

all native species and their habitat, such as the Sierra Nevada bighorn

sheep, that are threatened by extinction or are experiencing a

significant decline that, if not halted, would lead to a threatened or

endangered designation (California Fish and Game Commission 1999).

However, the Sierra Nevada bighorn sheep occurs mainly on Federal lands

administered by the BLM and the FS.

[[Page 27]]

These Federal agencies are responsible for regulating activities on

Federal lands that may adversely affect bighorn sheep. For example, the

State alone cannot effectively address disease transmission from

domestic sheep to Sierra Nevada bighorn sheep because the State does

not regulate grazing on Federal lands.

Since the Sierra Nevada bighorn sheep was listed by the State of

California in 1971, the CDFG has undertaken numerous efforts for the

conservation of the sheep, including but not limited to--(1) intensive

field studies; (2) reestablishment of three additional subpopulations

in historical habitat; (3) creation, in 1981, of the Sierra Nevada

Bighorn Sheep Interagency Advisory Group, including representatives

from Federal, State, and local resource management agencies, which has

produced the Sierra Nevada Bighorn Sheep Recovery and Conservation Plan

(1984) and a Conservation Strategy for Sierra Nevada Bighorn Sheep

(1997); and (4) culling four mountain lions that were taking Sierra

Nevada bighorn sheep, which played a significant role in the efforts to

reestablish one subpopulation (Chow 1991, cited by Wehausen (1996)).

Mountain lion hunting has not occurred in California since 1972

(Tories et al. 1996). As a result of passage of Proposition 117 in 1990

prohibiting the hunting or control of mountain lions, the CDFG lost the

authority to remove mountain lions to protect the Sierra Nevada bighorn

sheep and secure their survival. However, in September of 1999,

California passed legislation (A. B. 560) allowing the CDFG to take or

remove mountain lions that are a threat to the Sierra Nevada bighorn

sheep populations (D. Craig, in litt. 1999; Office of the Governor

1999). We believe that this law will help eliminate the threat due to

mountain lion predation, but will likely not completely eliminate it.

In addition, this legislation was enacted so recently that little time

has passed to allow us to evaluate its effectiveness as a regulatory

mechanism.

Federal agencies have authority to manage the land and activities

under their administration to conserve the bighorn sheep. Federal

agencies are taking steps to enhance habitat through prescribed burning

to improve forage and maintain open habitat, and to retire domestic

sheep allotments that run adjacent to bighorn sheep habitat. For

example, the FS burned 263 hectares (ha) (650 acres (ac)) in 1997 in

Lee Vining Canyon to reduce mountain lion hiding cover, and there are

plans to do more burns in other areas on FS land (R. Perloff, pers.

comm. 1999). However, in some cases, because of conflicting management

concerns, conservation efforts are not proceeding as quickly as

necessary. Although efforts have been underway for many years, the FS

has been unable to eliminate the known threat of contact between

domestic sheep and the Sierra Nevada bighorn sheep by either

eliminating adjacent grazing allotments, or modifying allotments such

that a sufficient buffer zone exists that would prevent contact between

wild and domestic sheep.

In 1971, the State, in cooperation with the FS, established a

sanctuary for the Mount Baxter and Mount Williamson subpopulation of

Sierra Nevada bighorn sheep and called it the California Bighorn Sheep

Zoological Area (Zoological Area) (Wehausen 1979; Inyo National Forest

Land Management Plan (LMP) 1988). The FS set aside about 16,564 ha

(41,000 ac) of FS land for these two subpopulations. At the time, many

felt that the species' decline was related to human disturbance. The

sanctuary was designed to regulate human use in some areas (Hicks and

Elder 1979), and reduce domestic sheep/wild sheep interaction by

constructing a fence below the winter range of the Mount Baxter

subpopulation along the FS and BLM boundary (Wehausen 1979). Adjacent

summer range on NPS land was also given a restrictive designation to

reduce human disturbance (Wehausen 1979). The FS continues to manage

the Zoological Area; it encompasses land designated as wilderness and

mountain sheep habitat (LMP 1988; R. Perloff, pers. comm. 1999).

Despite the establishment of the sanctuary, the sheep population

has continued to decline. This decline is most likely due to mountain

lion predation and the abandonment of low elevation winter range

(Wehausen 1996). Also, the sanctuary fence was constructed only at the

mouth of the canyon where the Mount Baxter herd winters, adjacent to a

stock driveway used to drive domestic sheep towards their summer

grazing allotments on Federal land further north (B. Pritchard, pers.

comm. 1999). The fence does not prevent domestic sheep from leaving

their bands while on the grazing allotments and moving into habitat

used by Sierra Nevada bighorn sheep.

E. Other Natural or Manmade Factors Affecting its Continued Existence

The Sierra Nevada bighorn sheep population is critically small with

a total of only 125 sheep known from 5 subpopulations. There is no

known interaction between the separate subpopulations. The Sierra

Nevada bighorn sheep currently is highly vulnerable to extinction from

threats associated with small population size and naturally occuring

events.

Although inbreeding depression has not been demonstrated in the

Sierra Nevada bighorn sheep, the number of sheep occupying all areas is

critically low. The minimum size at which an isolated group of this

species can be expected to maintain itself without the deleterious

effects of inbreeding is not known. Researchers have suggested that a

minimum effective population size of 50 is necessary to avoid short-

term inbreeding depression, and 500 to maintain genetic variability for

long-term adaptation (Franklin 1980). Small populations are extremely

susceptible to chance variation in age and sex ratios or other

population parameters (demographic stochasticity) and genetic problems

(Caughley and Gunn 1996). Small populations suffer higher extinction

probabilities from chance events such as skewed sex ratio of offspring,

(e.g., fewer females being born than males). For example, the Mount

Langley subpopulation has been declining. In 1996-97, out of a

subpopulation of 4 ewes and 10 rams, 5 lambs were born, of which 4 were

female. Although a positive event for this subpopulation, it could have

been devastating if the female:male ratio had been reversed (J.

Wehausen, pers. comm. 1999).

The five subpopulations include a total of nine female demes (i.e.,

local populations). These demes are defined by separate geographic home

range patterns of the females. Three of these demes appear not to use

low elevation winter ranges at all, and they will probably go extinct

as a result (J. Wehausen, pers. comm. 1999). For example, the Black

Mountain deme, consisting of five ewes, was previously part of the Sand

Mountain deme, which also has five ewes and is part of the Mount Baxter

subpopulation. The Black Mountain deme became a separate deme after

winter range abandonment in the late 1980s, and does not appear to know

of the Sand Mountain winter range, which lies considerably north of

their home range. This deme has shown a steady decline in size (J.

Wehausen, pers. comm. 1999).

There are six female demes that may persist, but all are still very

vulnerable to extinction due to small size. With the likely extinction

of some of the existing demes, the remaining demes become all the more

important to the persistence of this distinct population segment, and

each remaining female is critically important to her deme. Individual

mountain lions can do enormous

[[Page 28]]

damage to any of these small demes, as can catastrophic events such as

snow avalanches.

We also do not know the current distribution of genetic variation

among all of these subpopulations. Each subpopulation likely has lost

some genetic variability, thereby reducing its ability for long-term

adaptation. The ultimate goal of conserving this DPS must be to

preserve as much of its genetic variation a possible. It is likely that

all or some of the existing demes now contain some variation not

represented in others. Until some measure of the distribution of

genetic variation exists, every deme should be considered a significant

portion of the overall population. Maintenance of genetic variability

requires the preservation of rams in addition to ewes.

Small, isolated groups are also subject to extirpation by naturally

occurring random environmental events (e.g., prolonged or particularly

heavy winters and avalanches). In 1995, for example, a dozen sheep died

in a single avalanche at Wheeler Crest (J. Wehauser, pers. comm. 1999).

Such threats are highly significant because the subpopulations are

small and it is also common in bighorn sheep for all members of one sex

to occur in a single group. During the very heavy winters in the late

1970s and early 1980s, there was no notable mortality in the

subpopulations because they were using low elevation winter ranges (J.

Wehausen, pers. comm. 1999).

Competition for critical winter range resources can occur between

bighorn sheep and elk and/or deer (Cowan and Geist 1971). However,

competition between these species does not appear significant since

deer and bighorn sheep readily mix on winter range, and the habitat

overlap between elk and bighorn sheep is slight (Wehausen 1979).

In addition to disease, mountain lion predation, and naturally

occurring events, other factors may contribute to bighorn sheep

mortality. For example, two subpopulations (Wheeler Crest and Lee

Vining) have ranges adjacent to paved roadways, exposing individuals

from those subpopulations to potential hazards. Bighorn sheep have been

killed by vehicles in Lee Vining Canyon on several occasions (V.

Bleich, pers. comm. 1999).

We have carefully assessed the best scientific and commercial

information available regarding the past, present, and future threats

faced by this species in developing this final rule. All five

subpopulations of the Sierra Nevada distinct population of California

bighorn sheep are imperiled by disease, predation, naturally occurring

environmental events, and the continual loss of genetic variation if

the subpopulations remain small. The Sierra Nevada bighorn sheep

population reached a high of about 310 in 1985-86, but subsequent

population surveys have documented a declining trend. Currently, only

about 125 animals exist. The potential for contact with domestic sheep

and the transmission of disease could, by itself, eliminate an entire

deme. Domestic sheep continue to stray into Sierra Nevada bighorn sheep

habitat and come into close proximity to the resident bighorn sheep on

numerous occasions. However, domestic sheep have not come into contact

with bighorn sheep during these events. Vulnerability to demographic

problems must be viewed as a combination of immediate threats of

predation, changed habitat use due to the presence of mountain lions,

the resultant decline of ewe nutrition and lamb survivorship, exposure

to environmental catastrophes, and the transmission of disease from

domestic sheep. Because of the high potential for these threats to

result in the extinction of this bighorn sheep distinct population

segment, it warrants listing as endangered. Immediately upon

publication, this final rule will continue the protection for this DPS

of California bighorn sheep, which began when we emergency listed this

DPS on April 20, 1999.

Critical Habitat

In the emergency rule, we indicated that designation of critical

habitat was not determinable for the Sierra Nevada bighorn sheep due to

a lack of information sufficient to perform the required analysis of

impacts of the designation. We have re-examined the question of whether

critical habitat is not determinable, and have determined that there is

sufficient information to do the required analysis.

In the absence of a finding that critical habitat would increase

threats to a species, if there are any benefits to critical habitat

designation, then a prudent finding is warranted. In the case of this

species, there may be some benefits to designation of critical habitat.

The primary regulatory effect of critical habitat is the section 7

requirement that Federal agencies refrain from taking any action that

destroys or adversely modifies critical habitat (see Available

Conservation Measures section) . While a critical habitat designation

for habitat currently occupied by this species would not likely change

the section 7 consultation outcome, because an action that destroys or

adversely modifies such critical habitat would also be likely to result

in jeopardy to the species, there may be instances where section 7

consultation would be triggered only if critical habitat is designated.

Examples could include unoccupied habitat or occupied habitat that may

become unoccupied in the future. There may also be some educational or

information benefits to designating critical habitat. We find that

critical habitat is prudent for the Sierra Nevada bighorn sheep.

Our Final Listing Priority Guidance for FY 2000 (64 FR 57114)

states that the processing of critical habitat determinations (prudency

and determinability decisions) and proposed or final designations of

critical habitat will no longer be subject to prioritization under the

Listing Priority Guidance. Critical habitat determinations, which were

previously included in final listing rules published in the Federal

Register, may now be processed separately, in which case stand-alone

critical habitat determinations will be published as notices in the

Federal Register. We will undertake critical habitat determinations and

designations during FY 2000 as allowed by our funding allocation for

that year.'' As explained in detail in the Listing Priority guidance,

our listing budget is currently insufficient to allow us to immediately

complete all of the listing actions required by the Act. Deferral of

the critical habitat designation for the Sierra Nevada bighorn sheep

will allow us to concentrate our limited resources on higher priority

critical habitat and other listing actions, while allowing us to put in

place protections needed for the conservation of the Sierra Nevada

bighorn sheep without further delay. However, because we have

successfully reduced, although not eliminated, the backlog of other

listing actions, we anticipate in FY 2000 and beyond giving higher

priority to critical habitat designation, including designations

deferred pursuant to the Listing Priority Guidance, such as the

designation for this species, than we have in recent fiscal years.

We plan to employ a priority system for deciding which outstanding

critical habitat designations should be addressed first. We will focus

our efforts on those designations that will provide the most

conservation benefit, taking into consideration the efficacy of

critical habitat designation in addressing the threats to the species,

and the magnitude and immediacy of those threats. We will develop a

proposal to designate critical habitat for the Sierra Nevada bighorn

sheep as soon as feasible, considering our workload

[[Page 29]]

priorities. For the immediate future, most of Region 1's listing budget

must be directed to complying with numerous court orders and settlement

agreements, as well as due and overdue final listing determinations.

Available Conservation Measures

Conservation measures provided to species listed as endangered or

threatened under the Act include recognition, recovery actions,

requirements for Federal protection, and prohibitions against certain

activities. Recognition through listing encourages and results in

conservation actions by Federal, State, and private agencies, groups

and individuals. The Act provides for possible land acquisition and

cooperation with the States and requires that recovery actions be

carried out for all listed species. The protection required of Federal

agencies and the prohibitions against taking and harm are discussed, in

part, below.

Section 7(a) of the Act, requires Federal agencies to evaluate

their actions with respect to any species that is proposed or listed as

endangered or threatened, and with respect to its critical habitat, if

any is being designated. Regulations implementing this interagency

cooperation provision of the Act are codified at 50 CFR part 402. If a

species is listed, section 7(a)(2) requires Federal agencies to ensure

that activities they authorize, fund, or carry out are not likely to

jeopardize the continued existence of such a species or to destroy or

adversely modify its designated critical habitat. If a Federal agency

action may affect a listed species or its critical habitat, the

responsible Federal agency must enter into formal consultation with us.

Federal agency actions that may require conference and/or consultation

include those within the jurisdiction of the FS, BLM, and NPS.

We believe that protection of the Sierra Nevada bighorn sheep

requires reduction of the threat of mountain lion predation,

particularly during the months of April and May when bighorn sheep

attempt to use low elevation winter ranges to obtain necessary

nutrition after lambing, and ewes and lambs are most vulnerable to

predation. California's recently enacted legislation (A. B. 560)

allowing removal of mountain lions that threaten Sierra Nevada bighorn

sheep will reduce this threat. Removal of mountain lions may not

necessarily involve lethal techniques.

We believe that protection of the Sierra Nevada bighorn sheep also

requires reduction of the threat of disease transmission from domestic

sheep by preventing domestic sheep from coming into contact with

bighorn sheep. We will work with the FS to reduce the threat of disease

transmission by domestic sheep. Reduction of this threat may involve

elimination of grazing allotments adjacent to bighorn sheep habitat, or

modifying allotments to create a sufficient buffer zone that would

prevent contact between domestic sheep and bighorn sheep.

Listing this species would provide for the development of a

recovery plan. Such a plan would bring together both State and Federal

efforts for the conservation of the species. The plan would establish a

framework for agencies to coordinate activities and cooperate with each

other in conservation efforts. The plan would set recovery priorities

and estimate costs of various tasks necessary to accomplish them. It

also would describe site-specific management actions necessary to

achieve conservation and survival of the Sierra Nevada bighorn sheep.

Additionally, pursuant to section 6 of the Act, we would be able to

grant funds to affected states for management actions promoting the

protection and recovery of this species.

The Act and implementing regulations found at 50 CFR 17.21 set

forth a series of general prohibitions and exceptions that apply to all

endangered wildlife. The prohibitions, as codified at 50 CFR 17.21, in

part, make it illegal for any person subject to the jurisdiction of the

United States to take (including harass, harm, pursue, hunt, shoot,

wound, kill, trap, capture, collect, or attempt any such conduct),

import or export, transport in interstate or foreign commerce in the

course of commercial activity, or sell or offer for sale in interstate

or foreign commerce any endangered animal species. It is also illegal

to possess, sell, deliver, carry, transport, or ship any such wildlife

that has been taken illegally. Certain exceptions apply to our agents

and State conservation agencies.

Permits may be issued to carry out otherwise prohibited activities

involving endangered wildlife species under certain circumstances.

Regulations governing permits are at 50 CFR 17.22. For endangered

species, such permits are available for scientific purposes, to enhance

the propagation or survival of the species, or for incidental take in

connection with otherwise lawful activities.

It is our policy, published in the Federal Register on July 1, 1994

(59 FR 34272), to identify to the maximum extent practicable at the

time a species is listed those activities that likely would or would

not constitute a violation of section 9 of the Act. The intent of this

policy is to increase public awareness of the effect of a listing on

proposed and ongoing activities within a species' range. Activities we

believe will likely result in a violation of section 9 include, but are

not limited to:

(1) Unauthorized trapping, capturing, handling or collecting of

Sierra Nevada bighorn sheep. Research activities involving trapping or

capturing of Sierra Nevada bighorn sheep will require a permit under

section 10(a)(1)(A) of the Act.

(2) Failure to confine livestock to authorized grazing allotments

resulting in transmission of disease or habitat destruction.

Activities we believe will not likely result in a violation of

section 9 are:

(1) Possession, delivery, or movement, including interstate

transport and import into or export from the United States, involving

no commercial activity, of dead specimens of Sierra Nevada bighorn

sheep that were collected prior to April 20, 1999, the date of

publication of the emergency listing rule in the Federal Register;

(2) Normal, legal recreational activities in designated campsites

or recreational use areas, and on authorized trails.

Direct your questions regarding any specific activities to our

Ventura Fish and Wildlife Office (see ADDRESSES section). Requests for

copies of the regulations regarding listed wildlife and about

prohibitions and permits may be addressed to the U.S. Fish and Wildlife

Service, Ecological Services, Endangered Species Permits, 911 Northeast

11th Avenue, Portland, Oregon 97232-4181 (telephone 503/231-2063;

facsimile 503/231-6243).

National Environmental Policy Act

We have determined that an environmental assessment or

environmental impact statement, as defined under the National

Environmental Policy Act of 1969, need not be prepared in connection

with regulations adopted pursuant to section 4(a) of the Act. We

published a notice outlining our reasons for this determination in the

Federal Register on October 25, 1983 (48 FR 49244).

Paperwork Reduction Act

This rule does not contain any information collection requirements

for which Office of Management and Budget (OMB) approval under the

Paperwork Reduction Act, 44 U.S.C. 3501 et seq. is required. An

information collection related to the rule pertaining to permits for

endangered and

[[Page 30]]

threatened species has OMB approval and is assigned clearance number

1018-0094. An agency may not conduct or sponsor, and a person is not

required to respond to, a collection of information unless it displays

a currently valid control number. This rule does not alter that

information collection requirement. For additional information

concerning permits and associated requirements for endangered wildlife,

see 50 CFR 17.22.

References Cited

A complete list of references cited in this rule is available upon

request from the Ventura Fish and Wildlife Office of the U.S. Fish and

Wildlife Service (see FOR FURTHER INFORMATION CONTACT section).

Authors. The primary authors of this final rule are Carl Benz,

Ventura Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT

section), and Barbara Behan, Regional Office, 911 N.E. 11th Avenue,

Portland, Oregon 97232 (telephone 503/231-6131).

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and

recordkeeping requirements, Transportation.

Regulation Promulgation

Accordingly, we amend part 17, subchapter B of chapter I, title 50

of the Code of Federal Regulations, as follows:

PART 17--[AMENDED]

1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.

4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

2. Amend Sec. 17.11(h) by adding the following, in alphabetical

order under MAMMALS, to the List of Endangered and Threatened Wildlife:

Sec. 17.11 Endangered and threatened wildlife.

* * * * *

(h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------

Species Vertebrate

-------------------------------------------------------- population where Critical Special

Historic range endangered or Status When listed habitat rules

Common name Scientific Name threatened

--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * * * *

Mammals

* * * * * * *

Sheep, Sierra Nevada bighorn..... Ovis canadensis U.S.A. (western U.S.A., CA-Sierra E 660E NA NA

californiana. conterminous Nevada. 675

states), Canada

(southwest),

Mexico (north).

* * * * * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------

Dated: December 22, 1999.

Jamie Rappaport Clark,

Director, Fish and Wildlife Service.

[FR Doc. 99-34056 Filed 12-30-99; 8:45 am]

BILLING CODE 4310-55-P