[Federal Register Volume 59, Number 188 (Thursday, September 29, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-24065]


[[Page Unknown]]

[Federal Register: September 29, 1994]


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Part III





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17




Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Pacific Pocket Mouse; Final Rule
DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AC39

 
Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Pacific Pocket Mouse

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: The Fish and Wildlife Service (Service) determines the Pacific 
pocket mouse (Perognathus longimembris pacificus) to be an endangered 
species throughout its range in coastal southern California, pursuant 
to the Endangered Species Act of 1973, as amended (Act). Critical 
habitat is not being designated. This small rodent is an obligate 
resident of river and marine alluvium and coastal sage scrub plant 
communities in the immediate vicinity of the coast. Although the 
Pacific pocket mouse formerly occurred at a minimum of 8 general 
locales encompassing some 29 sites from Los Angeles County south to San 
Diego County, the only known, confirmed population extant occurs on the 
Dana Point Headlands in Orange County, California. A maximum of 36 
confirmed, individual Pacific pocket mice has been detected on 3.75 
acres of identified occupied habitat during the last 20 years. The 
Pacific pocket mouse is threatened with extinction due to documented 
depredation by domestic cats and habitat loss and fragmentation as a 
result of past and continuing land development projects. This rule 
implements and guarantees continued Federal protection provided by the 
Act for the Pacific pocket mouse, which was emergency listed as 
endangered on January 31, 1994 for a period of 240 days.

EFFECTIVE DATE: September 26, 1994.

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: Mr. Gail C. Kobetich, Field 
Supervisor, at the address listed above (telephone 619/431-9440).

SUPPLEMENTARY INFORMATION:

Background

    The Pacific pocket mouse (Perognathus longimembris pacificus) is 
one of 19 recognized subspecies of the little pocket mouse (Perognathus 
longimembris) (Hall 1981). This species is one of the smallest members 
of the family Heteromyidae, which consists of spiny pocket mice 
(Heteromys and Liomys), pocket mice (Perognathus and Chaetodipus), 
kangaroo rats (Dipodomys), and kangaroo mice (Microdipodops). Virtually 
all (if not all) members of this family are nocturnal, granivorous and 
have external, deep, fur-lined cheek pouches (Ingles 1965; Dr. P. 
Brylski, consulting mammalogist, pers. comm., 1993).
    Perognathus longimembris ranges in size from about 110 to 151 
millimeters (mm) (4.3 to 5.9 inches) from nose to tip of tail (Hall 
1981) and weighs 7 to 9 grams (\1/4\ to \1/3\ oz.) (Burt and 
Grossenheider 1976). The body pelage is spineless, bristle-free, and 
predominately brown, pinkish buff or ochraceous buff above and light 
brown, pale tawny, buff, or whitish below. There are typically two 
small patches of lighter hairs at the base of the ear. The tail can be 
either distinctly or indistinctly bicolored. The little pocket mouse 
exhibits a high degree of geographic variation in pelage color (Hall 
1981; see also Ingles 1965). Vocalizations of this species include a 
high-pitched squeal.
    The Pacific pocket mouse is the smallest subspecies of the little 
pocket mouse, ranging up to 131 mm (5.2 inches) in length from nose to 
tip of the long tail. The tail, hind foot, and skull structures of 
Pacific pocket mice are also the smallest of all little pocket mouse 
subspecies (Huey 1939). Stephens (1906) labeled the species an ``* * * 
exceedingly small [p]ocket [m]ouse * * *'' The Pacific pocket mouse is 
one of the smallest rodents in the world.
    The Los Angeles pocket mouse (Perognathus longimembris brevinasus), 
which occurs mostly northeast of, and well inland from, the Pacific 
pocket mouse, is the only other subspecies of little pocket mouse that 
occurs in southern California west of the deserts. Individual Los 
Angeles pocket mice range in size from 125 to 145 mm (4.9 to 5.7 
inches) long. Overall, Los Angeles pocket mice have longer tails, hind 
feet, skulls, and nasal bones than Pacific pocket mice (Huey 1939).
    The Pacific pocket mouse was originally described by Mearns (1898) 
as a distinct species, Perognathus pacificus, based on the type 
specimen that was collected on the shore of the Pacific Ocean at 
Mexican Boundary Monument 258 in San Diego County, California. Although 
von Bloeker (1931a,b) initially recognized the Pacific pocket mouse as 
a distinct species, he subsequently concluded that P. pacificus 
represented two subspecies of the little pocket mouse, P. longimembris 
pacificus and P. l. cantwelli, after examining additional specimens 
(von Bloeker 1932). Subsequent to a biometric analysis of 331 specimens 
of the little pocket mouse, Huey (1939) recognized P. l. pacificus to 
be inclusive of the two subspecies described by von Bloeker (1932). 
Subsequent taxonomic treatments (e.g., Hall 1981; Williams et al. 1993) 
have retained the Pacific pocket mouse as a distinct subspecies. 
Although a taxonomic review of P. longimembris may be appropriate, the 
Pacific pocket mouse has been described as distinct from related forms 
(Dr. D. Williams, mammalogist, in litt, 1993).
    Under section 3(15) of the Act (16 U.S.C. 1531 et seq.), the term 
``species'' is defined to include recognized subspecies. Therefore, 
throughout the remainder of this rule, Perognathus longimembris 
pacificus (hereafter referred to as the Pacific pocket mouse), is 
treated as a ``species''.
    The Pacific pocket mouse is endemic to the immediate coast of 
southern California from Marina del Rey and El Segundo in Los Angeles 
County, south to the vicinity of the Mexican border in San Diego County 
(Hall 1981, Williams 1986, Erickson 1993). The species has not been 
recorded outside of California (Williams et al. 1993; Erickson 1993). 
Erickson (1993) noted further that the Pacific pocket mouse has not 
been reliably recorded more than approximately 2 miles (3 kilometers) 
inland from the coast or above 600 feet (180 meters) in elevation.
    The habitat requirements of the Pacific pocket mouse are not well 
understood, but they are known to occur on fine-grain, sandy substrates 
in the immediate vicinity of the Pacific Ocean (Mearns 1898, von 
Bloeker 1931; Grinnell 1933; Bailey 1939). The Pacific pocket mouse is 
or was known to inhabit coastal strand, coastal dunes, river alluvium, 
and coastal sage scrub growing on marine terraces (Grinnell 1933; 
Meserve 1972; Erickson 1993). Stephens (1906) trapped a female ``* * * 
on a dry mesa a short distance back from the seashore.'' von Bloeker 
(1931a) reported that Pacific pocket mice detected near San Diego were 
found only in open patches of ground that were otherwise surrounded by 
weedy growth. M'Closkey (1972) and Meserve (1972, 1976b) detected the 
Pacific pocket mouse on sandy substrates in coastal sage scrub habitats 
in the San Joaquin Hills in Orange County, California. Brylski (1993) 
detected the only known, confirmed population extant on the Dana Point 
Headlands on loose sand substrates in a coastal sage scrub community 
dominated by California buckwheat (Eriogonum fasiculatum) and 
California sage (Artemisia californica). Brylski (1993) commented that 
the Pacific pocket mouse's preferred habitat ``* * * appears to be open 
coastal sage scrub on fine, sandy soil.''
    Little quantitative information is available on the ecology and 
life history of the Pacific pocket mouse. However, the attributes of 
the little pocket mouse and the available data that pertain to the 
Pacific pocket mouse subspecies suggest that this small rodent is 
facultatively or partially fossorial, relatively sedentary, primarily 
granivorous, and able to become torpid, estivate, or hibernate in 
response to adverse environmental conditions (e.g., Ingles 1965; Kenagy 
1973; Dr. P. Meserve, academic mammalogist, pers. comm., 1994; Dr. R. 
MacMillan, academic mammalogist, pers. comm., 1994).
    During those periods that they are not active on the surface of 
preferred substrates or in preferred habitats, Pacific pocket mice 
apparently dwell in underground burrows. Erickson (1993) noted that 
``[n]umerous small burrows revealed the presence of some colonies to 
early collectors.'' Kenagy (1973) observed that little pocket mice may 
stay in their burrows continuously for up to five months in winter, 
alternating between periods of dormancy and feeding on stored seeds. 
Periods of dormancy apparently may be induced by, or correlated with, 
food shortage (Kenagy 1973). Ingles (1965) noted that ``[t]he ability 
of the little pocket mouse to become dormant for only a few bad nights 
is an important factor in its survival.''
    While active and above ground, little pocket mice have ranged up to 
1,000 feet (320 meters) from their burrows in a 24-hour period (Burt 
and Grossenheider 1976). However, based on his study from 1969-1973 in 
the Owens Valley, California, Kenagy (1973) concluded that ``* * * the 
maximum distance moved during the night by this little mouse was 
undoubtedly much less than 50 m.'' Reported little pocket mouse home 
ranges ranged in size from 0.12 to 0.56 hectares (0.30 to 1.4 acres) 
and populations ranged in density from 1 to 5.5 individuals/hectare 
(0.4 to 2.2 individuals/acre) in Joshua Tree National Monument, 
California (Chew and Butterworth 1964). Adult density at Dana Point 
Headlands was estimated to be 5.9/hectare (2.4/acre) by Brylski (1993).
    Pacific pocket mice primarily eat the seeds of grasses and forbs 
(von Bloeker 1931; Meserve 1972, 1976a). Meserve (1976a) observed 
further that other plant materials were consumed, albeit in 
comparatively smaller quantities. P. Brylski (pers. comm., 1993) 
observed that ``Pacific pocket mice foraged mainly on the seeds of 
grasses and, to a lesser degree, on leafy vegetation.'' Jameson and 
Peeters (1988) reported that little pocket mice, like other pocket mice 
species, also eat soil-dwelling insects.
    Relatively little is known of the breeding biology of Pacific 
pocket mice. Erickson (1993), relying largely on data provided by 
Meserve (1972), noted that ``[p]regnant and lactating females have been 
found from April through June with immatures noted from June through 
September.'' P. Brylski (pers. comm., 1993) observed lactating females 
in July and noted that two litters were produced that year. Limited 
reproduction was attributed to juveniles in the Dana Point Headlands 
population (P. Brylski, pers. comm., 1993). Jameson and Peeters (1988) 
described the little pocket mouse as ``rather prolific'' and indicated 
that ``[p]regnancies occur in spring and fall with a summer lull.''
    Historical records indicate that the Pacific pocket mouse occurred 
in 8 general areas encompassing some 29 separate trapping sites. 
Approximately 80 percent of all Pacific pocket mouse records are from 
1931 or 1932 (Erickson 1993). The following summary of records is 
organized by county:
    Los Angeles County. The Pacific pocket mouse historically was 
detected in three areas--Marina del Rey/El Segundo, Wilmington, and 
Clifton. One hundred and eighteen specimens or live captures were 
recorded for the Marina Del Rey/El Segundo area from 1918 to 1938, with 
most (86) of these records coming from ``Hyperion''; see Erickson 
(1993). Three specimens were collected in Wilmington in 1865 (voucher 
specimens on deposit at the Museum of Vertebrate Zoology, University of 
California, Berkeley) and four were collected in ``Cliffton'' [sic] in 
1931. Four specimens from San Fernando in 1932 that were originally 
labeled as P. pacificus/P. cantwelli were referred to as P. l. 
brevinasus by von Bloeker (1932); see Erickson (1993). There have been 
no records of Pacific pocket mice from Los Angeles County since 1938 
(Erickson 1993; P. Brylski, in litt, 1993).
    Orange County. The Pacific pocket mouse has been confirmed at two 
locales in Orange County: the San Joaquin Hills and Dana Point. The 
species was found in Buck Gully (P. Meserve, pers. comm., 1994) and 
nearby ``Spyglass Hill'' in the San Joaquin Hills from 1968 to 1971 
(M'Closkey 1972; Meserve 1972; R. MacMillan, pers. comm., 1994). Forty-
four specimens or live captures from ``Spyglass Hill'' were recorded 
from 1968-1971 (see Erickson 1993). The only known, confirmed 
population extant of the Pacific pocket mouse was rediscovered in July 
of 1993 on the Dana Point Headlands in Orange County, California 
(Brylski 1993). G. Cantwell had previously collected 10 specimens of 
this species at this locale in May of 1932 (voucher specimens on 
deposit at the Natural History Museum of Los Angeles County).
    Possible, recent records from Crystal Cove State Park (approx. 16 
km (10 mi) NW Dana Point) resulting from pitfall trapping (see R. 
MacMillan, pers. comm., 1994) await confirmation given the uncertainty 
expressed by the observer and the negative results of recent walk-over 
and trapping surveys there (see P. Brylski, in litt, 1994 and J. Webb, 
in litt, 1994).
    San Diego County. The Pacific pocket mouse historically was 
confirmed at three general locales in San Diego County--the San Onofre 
Area, Santa Margarita River Estuary, and the lower Tijuana River 
Valley. One specimen was obtained at San Onofre in 1903 and two others 
were secured at that locale in 1931. Seventy-one specimens or live 
captures were recorded for the Santa Margarita River mouth area between 
1931 and 1936, with the majority (50) of these reported for 
``Oceanside''. One hundred and thirty-four specimens or live captures 
have been recorded from the lower Tijuana River Valley, including the 
type specimen. There has not been a confirmed Pacific pocket mouse 
record at these locales or elsewhere in San Diego County since 1932 
(see Erickson 1993).
    However, there have been three recent, unconfirmed reports of the 
Pacific pocket mouse from San Diego County. A document released by the 
California Department of Fish and Game (Mudie et al. 1986) pertaining 
to the wildlife resources at the San Dieguito Lagoon, Del Mar, and at 
least one subsequent environmental ``baseline study'' pertaining to 
that locale (see S. Montgomery, consulting biologist, in litt, 1994 and 
R. Erickson, consulting biologist, pers. comm., 1994) provide species 
lists that contain the little pocket mouse (Perognathus longimembris). 
Given the location of the survey effort, it seems almost certain that 
any and all little pocket mice recorded at this locale would be Pacific 
pocket mice. However, it was subsequently ascertained that none of the 
surveyors or report authors could recall capturing a little pocket 
mouse on the site or reporting same (e.g., Montgomery in litt, 1994; R. 
Erickson, consulting biologist, pers. comm., 1994). Subsequent walk-
over surveys of the area in 1992 did not reveal the presence of the 
Pacific pocket mouse (Dr. P. Behrends, consulting mammalogist, pers. 
comm., 1994).
    A single Pacific pocket mouse was reported from Lux Canyon, 
Encinitas, in June 1989. The record is now considered only probable by 
the observer (Erickson 1993).
    Most recently and since the publishing of the proposed and 
emergency rules, Mr. S. Tremor (in litt, 1994) reported what he 
believes to be a single Pacific pocket mouse from a locale in Del Mar, 
California. However, the animal escaped before photographs or a pelage 
description could be obtained. Given these considerations, the Service 
concludes, in the present absence of definitive or additional 
information, that the Del Mar observation, although certainly deserving 
of further attention and investigation, remains unconfirmed until such 
time that a positive species identification can be made. P. Brylski 
(pers. comm., 1994) independently has arrived at the same conclusion.
    Accordingly, the only known, recently confirmed population of the 
Pacific pocket mouse extant remains on the Dana Point Headlands. 
Between 25 to 36 individual Pacific pocket mice were detected there by 
Brylski (1993) during trapping surveys that extended into August. Prior 
to this recent rediscovery of the Pacific pocket mouse at the Dana 
Point Headlands, the Pacific pocket mouse had not been positively 
observed since 1971 (see Erickson 1993). Numerous, relatively recent 
small-mammal survey and trapping efforts within the potential range of 
the Pacific pocket mouse (e.g., Salata 1981; Jones and Stokes 1990; 
Taylor and Tiszler 1991; D. Erickson, pers. comm. 1993; P. Brylski, in 
litt, 1993; P. Behrends, pers. comm., 1994; Dr. P. Kelly, mammalogist, 
pers. comm., 1994; R. MacMillan, pers. comm., 1994; Dr. R. Dingman, 
mammalogist, pers. comm., 1994; Dr. J. Webb, biologist, in litt, 1994; 
S. Montgomery, consulting biologist, in litt, 1994; P. Brylski, in 
litt, 1994; United States Fish and Wildlife Service 1994a; United 
States Fish and Wildlife Service 1994b) have failed to locate 
additional extant populations.
    From a species perspective, the persistence of the Pacific pocket 
mouse is important, perhaps essential, in preserving an important and 
unique portion of the historic habitat of the little pocket mouse and 
in preserving potentially unique genetic stock. The Pacific pocket 
mouse's adaptation to, and dependence on, coastal dune and coastal 
alluvium substrates and coastal sage scrub habitats have probably 
contributed to a genetic divergence from other subspecies of the little 
pocket mouse. Maintaining a broad genetic stock may be critically 
important to the species ability to adapt to changing environmental 
conditions. The apparent sedentary nature of the Pacific pocket mouse 
(Meserve 1972; Meserve, pers. comm., 1994) and the fragmentation of 
this species' potential habitat increase the probability that localized 
extirpations caused by the destruction of habitat or movement corridors 
will be permanent. This could significantly reduce the extent of any 
possible introgression between subpopulations and reduce genetic 
heterozygosity and the overall fitness of the species. Such 
perturbations could result in a permanent loss of genetic stock or, at 
the extreme, result in the extinction of the Pacific pocket mouse.

Previous Federal Action

    The Pacific pocket mouse was designated by the Service as a 
category 2 candidate species for Federal listing as an endangered or 
threatened species in 1985 (50 FR 37966). It was retained in this 
category in subsequent notices of review published by the Service in 
the Federal Register in 1989 and 1991 (54 FR 554 and 56 FR 58804, 
respectively). Category 2 comprises taxa for which information now in 
the possession of the Service indicates that proposing to list as 
endangered or threatened is possibly appropriate, but for which 
conclusive data on biological vulnerability and threat are not 
currently available to support proposed rules.
    Largely because of documented, imminent threats to the only known 
population of the Pacific pocket mouse, the Service published an 
emergency rule to list the species as endangered on February 3, 1994 
(59 FR 5306). Interim protection afforded the Pacific pocket mouse as 
the result of the promulgation of the emergency rule expires on 
September 28, 1994. A proposed rule to list the Pacific pocket mouse 
was concurrently published with the emergency rule (59 FR 5311).

Summary of Comments and Recommendations

    In the proposed rule and associated news release announcing the 
promulgation of the proposed rule and emergency rule, all interested 
parties were requested to submit factual reports or information that 
might contribute to the development of a final rule. The news release 
was provided to media throughout southern California and to the 
national media. In addition, 3 Federal agencies, 3 state agencies, 15 
county and city governments, and 6 other potentially affected or 
interested parties were individually notified of the promulgation of 
the emergency and proposed rules. Representatives of Marine Corps Base, 
Camp Pendleton; the County of Orange; the City of Dana Point; and the 
Dana Point Headlands landowner, among others, were personally contacted 
by Service personnel. Newspaper articles in the Los Angeles Times and 
Orange County Register announcing the emergency listing of the Pacific 
pocket mouse and scheduled public hearing appeared in February and 
March 1994.
    The Service held a public hearing on the proposed rule on March 24, 
1994, in San Clemente, Orange County, California. Notification of the 
hearing was published in the Federal Register on March 1, 1994 (59 FR 
9720). Newspaper notices specifically announcing the hearing and 
inviting general public comment on the proposal additionally were 
published in the Orange County Register and San Diego Union Tribune. 
Approximately 25 people attended the hearing and seven of these 
provided oral comments.
    A total of 71 comments was received. Although the comment period 
technically closed on April 4, 1994, the Service considered all 
comments received through June 20, 1994. (Five comments were received 
by the Carlsbad Field Office after the deadline, including one from an 
interested and potentially affected municipal jurisdiction.) Multiple 
comments whether written or oral from the same party are regarded as 
one comment.
    Of the comments received, 48 persons or organizations (68 percent) 
supported listing; 10 (14 percent) urged the protection of the only 
confirmed, occupied habitat of the Pacific pocket mouse on the Dana 
Point Headlands; 3 (4 percent) were against the listing; 3 (4 percent) 
were in favor of the development of the Dana Point Headlands; 4 (6 
percent) urged the application of sound science to the listing process; 
and 3 (4 percent) were noncommittal.
    Two Federal agencies and the sole city government responding were 
neutral on the issue of listing. The California Department of Fish and 
Game previously had gone on record as supporting a proposal to list the 
Pacific pocket mouse (K. Berg, in litt, 1992). No citizens groups or 
organizations opposed the proposed listing. Attorneys for one landowner 
voiced opposition to both the emergency listing and proposed listing.
    The Service has reviewed all of the written and oral comments 
described above including those that were received outside of the 
formal comment periods. Based on this review, 11 relevant issues have 
been identified and are discussed below. The Service considers these 
issues to be representative of the comments questioning or opposing the 
proposed listing action.
    Issue 1: One commenter noted that the listing action should not 
occur because the Pacific pocket mouse subspecies is not a valid taxon 
and the subject of taxonomic controversy. The commenter quotes a letter 
from Mr. P. Collins, Associate Curator of the Santa Barbara Museum of 
Natural History, to D. Erickson, in which it is stated that ``* * * I 
think that it is imperative that the taxonomic status of the various 
subspecies of Perognathus longimembris in central and southern 
California be reevaluated using modern systematic techniques such as 
electrophoresis and multivariate morphometrics. The systematic 
questions will need to be answered before any population of this 
species can be proposed for possible listing status.'' The commenter 
further noted that ``* * * Service officials appeared to have 
significant concerns regarding the appropriateness of listing the PPM 
[Pacific pocket mouse] in the absence of sufficient data on the 
taxonomy issue--even as recently as November 1993. (Exhibit J)'' The 
Service is obliged to consider available data pertaining to the genetic 
relationship between the Pacific pocket mouse and other groups of 
little pocket mice as provided by Patton et al. (1981). The commenter 
added that the subspecies designation is controversial and that ``* * * 
alleged morphological characteristics could be the product of seasonal 
or ecological variation among pocket mice. A proper resolution of the 
resolution of the PPM's true status is required before the Service can 
act to list the PPM as a subspecies. * * *''
    Service Response: Although the Service initially and independently 
reviewed all available information relating to the taxonomy, ecology, 
biology, status and distribution of the Pacific pocket mouse, the 
Service also solicited comments or suggestions from the public, other 
concerned governmental agencies, the scientific community, industry, 
and any other interested party on these and all other aspects of the 
proposed rule. In particular, the Service has made a concerted effort 
to obtain the best available scientific information regarding the 
taxonomy of the Pacific pocket mouse.
    Despite a recent taxonomic treatment of the rodent family 
Heteromyidae published by the American Society of Mammalogists 
(Society), the Service nonetheless solicited the expert opinions and 
input of, among others, the President of the Society and the principal 
author of the published taxonomy (Williams et al. 1993) regarding the 
taxonomic validity of Perognathus longimembris pacificus. The Service 
considers the Society to be a recognized authority on the taxonomy and 
biology of North American mammals.
    As is suggested by the commenter, the Service does have significant 
concerns regarding the appropriateness of listing any species and 
carefully considers its mandate in that regard as set forth by section 
4 of the Act. In the present case, however, the Service cannot agree 
that there is, as suggested by the commenter, an absence of sufficient 
data pertaining to the taxonomy of the Pacific pocket mouse.
    The Pacific pocket mouse was originally described by Mearns (1898) 
as a distinct species, Perognathus pacificus. Subsequent to several 
intervening taxonomic treatments or investigations (e.g., Stephens 
1906; von Bloeker 1932; Grinnell 1933; Huey 1939), Hall (1981) and 
others have recognized the Pacific pocket mouse as a distinct 
subspecies of the little pocket mouse. Although the taxonomical history 
of this species spans some 90 years and there is a current, peer-
reviewed, published classification of the heteromyid rodents inclusive 
of the pocket mice taxa (Williams et al. 1993), the Service 
nevertheless contacted Dr. Williams to insure that there was no doubt 
as to the current, correct taxonomic treatment of the subject 
subspecies (see D. Williams, in litt, 1993, which is identical to the 
commenter's Exhibit J). Dr. Williams (in litt, 1993) confirmed the 
taxonomic validity and distinctness of the Pacific pocket mouse.
    Although it is recognized that a ``* * * modern revision of the 
longimembris complex might cause a re-evaluation of the various 
subspecies of this taxon'', the Service presently has no information or 
scientific basis to refute a recognized authority's assertion that ``* 
* * there is certainly every reason to consider pacificus valid with 
current information'' (Dr. J. L. Patton, President of the American 
Society of Mammalogists, in litt, 1994). Patton et al. (1981) did not 
address the biochemical systematics of perognathine pocket mice (which 
include the little pocket mouse and Pacific pocket mouse).
    Mr. Collins has informed the Service (pers. comm., 1994) that he 
has no alternative taxonomy to propose and is not now, and will not be 
in the foreseeable future, investigating the taxonomy of Perognathus 
longimembris. By contrast, P. Brylski has indicated (in litt, 1993) 
that he and others are currently investigating the systematics of 
Perognathus longimembris utilizing sequencing regions of mitochondrial 
DNA and morphology. To date, no results from these studies have been 
published or are otherwise forthcoming. In the interim, P. Brylski (in 
litt, 1994) has most recently indicated that ``[a]t this time, there is 
no evidence that contradicts the taxonomic distinctiveness of P. 
longimembris pacificus.''
    The traditional scientific approach to defining vertebrate 
subspecies has been based almost exclusively on the identification of 
morphological differences in body measurements and other morphometric 
characters between geographically distinct populations of a species. 
Given its apparent, current rarity, limited mobility, and distance from 
other subspecies of the little pocket mouse (see, for instance, Meserve 
1972; Hall 1981; P. Brylski, in litt, 1993; Erickson 1993) and the 
definition and expected course of speciation, it seems reasonable to 
assume that the Pacific pocket mouse is now, or will be, a de facto 
``full'' species or genetically-isolated taxonomic entity unto itself.
    In the absence of current, definitive information to the contrary 
from an expert (or any other) source, the Service presently concludes 
that the Pacific pocket mouse subspecies constitutes a valid taxon.
    Issue 2: The same commenter concluded that the proposed rule must 
be withdrawn because the Service improperly and secretly elevated the 
species to a category 1 candidate status on the basis of new 
information that was obtained in 1993.
    Service Response: The three candidate levels (1-3) used by the 
Service are administratively defined to periodically advise the public 
on the status of various taxa that might come under the protection of 
the Act. The terms ``candidate'' or ``category 1'' do not appear in the 
Act or implementing regulations in 50 CFR. The Service had previously 
notified the public in its candidate notices of review (e.g., 56 FR 
58805) that when sufficient information was available, a proposed rule 
might result. Section 4(b)(7) of the Act specifically authorizes the 
Service to promulgate emergency rules when the well-being of a species 
is at significant risk. A species need not be a previously declared 
category 1 candidate species to meet the criteria for threatened or 
endangered status and to be proposed accordingly or to have an 
emergency rule promulgated. For reasons that are fully explored in the 
``Summary of Factors'' portions of the February 3, 1994, emergency rule 
(59 FR 5306) and this rule, the Service concludes that the Pacific 
pocket mouse fully met and still meets the criteria necessary to 
promulgate a rule listing the species as endangered.
    The new information obtained in 1993 consists of all materials and 
data that became available to the Service pertaining to, in part, the 
status, distribution, ecology, and biology of the Pacific pocket mouse. 
Included in these submittals was an updated manuscript by R. Erickson 
(1993). Accompanying this manuscript were records of Pacific pocket 
mouse museum or collection specimens and related documentation, raw 
data and notes reflecting searches for additional Pacific pocket mice 
records, peer-review correspondence, communications with experts in the 
field, an updated bibliography, and other, relevant materials. Also 
received in 1993 were Brylski's (1993) report and additional 
correspondence (P. Brylski, in litt, 1993) that confirmed the 
rediscovery of the Pacific pocket mouse on the Dana Point Headlands. 
During the prescribed public comment period, the commenter viewed and 
photographed or otherwise received all such materials.
    Subsequent to an examination of all pre-existing information and 
important, additional data received in 1993, the Service concluded that 
sufficient data and information existed to list the Pacific pocket 
mouse on an emergency basis pursuant to section 4 of the Act and 
implementing regulations pertaining thereto. Given the information and 
data that has been forthcoming since that time, the Service concludes 
that the emergency listing was appropriate and that the species 
continues to meet the criteria as an endangered species.
    Issue 3: The same commenter observed that the ``* * *[p]roposed 
rule should be withdrawn because the Service lacks scientific data to 
support a listing of the PPM as threatened or endangered.'' The Service 
currently has insufficient information to assess the status and 
distribution of the Pacific pocket mouse. Specifically, the commenter 
argued ``* * *that a substantial number of trap nights-- perhaps a 
minimum of roughly 500--must be employed in any survey effort deemed to 
have any relevance for reaching conclusions on presence/absence. 
Consistent with this need for reliable data, the M.H. Sherman Company 
conducted 643 trap nights during its survey efforts at the Dana 
Headlands site.'' The commenter further argued that the majority of 
other recent surveys either were conducted ``* * *when the PPM can be 
expected to be dormant* * *'' (e.g., Taylor and Tiszler 1991) or at 
``[s]ites for which no survey dates are provided (and thus cannot be 
considered to provide reliable presence or absence data)* * *'' (e.g., 
the Santa Margarita River Mouth). ``An examination of the data for just 
the eight (8) locations historically known to have occupied habitat* * 
*reveals a similar lack of information upon which to draw a conclusion 
about the appropriateness of listing. The Service's own document 
indicates that a live trapping program is needed before the 
appropriateness of any listing can be made.'' Another commenter 
encouraged the Service ``* * *to fully investigate all remaining 
historic habitats as well as potential habitat areas for the Pacific 
pocket mouse before making a final determination on its status.'' One 
commenter concluded that ``[t]he Service's failure to establish and 
publish the accepted survey protocol for the PPM prior to the close of 
the public comment period renders this rule-making process invalid.''
    Service Response: In response to similar comments regarding the 
proposed listing of three Gulf Coast beach mice species (Peromyscus), 
the Service (June 6, 1985, 50 FR 23874) argued that ``[i]t is not 
necessary to have precise population numbers to determine that the 
beach mice are endangered; indeed, it would probably be impossible to 
obtain such numbers.'' In that instance, the Service concluded that the 
three beach mice were endangered after a thorough review of adequate, 
relevant population data and documentation of habitat loss or 
perturbation, documented depredation, and other factors affecting the 
species.
    In consistent fashion, the Service has made every attempt to obtain 
the best scientific information and data relating to the status of the 
Pacific pocket mouse and the factors affecting that species. Subsequent 
to a thorough consideration of these data and information, the Service 
concludes that said data and information are adequate and collectively 
support a listing as endangered. In particular, a composite of the 
relevant data summarized and reported by Hall (1981), Williams (1986), 
Williams et al. (1993), and Erickson (1993), the specimen records at 
institutions throughout California, and the additional data, 
references, and records summarized herein demonstrates that there in 
not a paucity of relevant information on the Pacific pocket mouse or 
the small rodent species of southern California in general.
    An analysis of this very same information reveals that credible 
determinations of presence/absence of the Pacific pocket mouse (and 
many other small rodent species) depend on a number of factors that are 
not a function of the number of survey trap nights. Legitimate small 
mammal trappers in California are all licensed by the California 
Department of Fish and Game and many possess endangered species permits 
from the Service. These scientific surveyors are professionally 
obligated and charged with knowing the conditions and circumstances 
that will maximize the chances of detecting the Pacific pocket mouse 
during focused surveys or otherwise result in an adequate 
characterization of the rodent community at any given locale. An 
adequate assessment of the appropriate number of trap nights and number 
of trapping bouts during a given survey should reflect the experience 
of the surveyor and will certainly incorporate, at a minimum, the 
results of walk-over surveys for small rodent sign and burrows, 
analyses of the size and physical characteristics of the area being 
surveyed, the adjudged, current trappability of the target species, 
apparent suitability or ``quality'' of site habitat(s), time of year, 
phase of the moon, and the climatic conditions. Thus, a given focused 
survey for the Pacific pocket mouse may appropriately require far less 
than, or far greater than, five hundred trap nights.
    All of the above considerations are factored into the Service's 
guidelines for surveying the Pacific pocket mouse (U.S. Fish and 
Wildlife Service 1994c) and it is likely that the protocol will evolve 
pursuant to the recommendations of permitted surveyors and expert 
sources. Although the Service has stipulated a minimum of five trapping 
bouts at each site to reflect the rarity and possible difficulty in 
locating or trapping the Pacific pocket mouse (e.g., Erickson 1993; 
Behrends, in litt, 1994), it is further stated that ``[a] lesser effort 
may be approved by the Carlsbad Field Office on a case by case basis.'' 
(U.S. Fish and Wildlife Service 1994c). If, for instance, the objective 
is to merely establish presence/absence at a given locale, then a 
lesser effort may well be justified if Pacific pocket mice are detected 
in the first four trapping bouts. The recent, successful trapping 
survey at the Dana Point Headlands is a case in point. Although the 
Service concedes that the 643 trap-night effort at that locale in 1993 
was justified, in that particular instance, to establish the 
approximate range and extent of the local Pacific pocket mouse 
population, it is nonetheless true that 9 Pacific pocket mice were 
discovered during the first night of trapping subsequent to the 
placement of 60 ``effective'' live traps at the site (Brylski 1993).
    Even though it is apparent that Pacific pocket mice have not been 
recorded in December, January, or February of any given year (see 
Erickson 1993) and that the species apparently is most detectable from 
April to August (e.g., Meserve 1972), it cannot be assumed that the 
species is entirely undetectable during winter months. Subsequent to 
his long-term (1969-1973) study of the little pocket mouse at an 
elevation of approximately 1,220 meters (4,000 feet) in the Owens 
Valley, California, Kenagy (1973) observed that ``[t]he extent of 
winter activity in the population of P. longimembris was different in 
each of the three winters, ranging from zero to 5 months of activity.* 
* *'' Thus, the Service cannot automatically assume that trapping 
surveys during winter months are of no value in determining the 
presence/absence of the Pacific pocket mouse. If Pacific pocket mice 
are active during a given period in winter, however, surface sign 
should be visible. In any case, a review of the methodology employed by 
Taylor and Tiszler (1991) reveals that ``[t]rapping began in November 
of 1988 and was completed May 1989.'' Thus, these authors did conduct 
trapping in at least portions of 4 calendar months during which Pacific 
pocket mice have been recorded (Taylor and Tiszler 1991; see also 
Erickson 1993).
    In the emergency rule, R. Zembal, U.S. Fish and Wildlife Service 
(pers. comm., 1993), is cited as a source to corroborate the statement 
that recent small trapping efforts at the Santa Margarita River Mouth 
have failed to detect the presence of the Pacific pocket mouse (59 FR 
5307). As is reflected in the Pacific pocket mouse species file at the 
Carlsbad Field Office, the referenced communication was ``[t]he Service 
has looked repeatedly and intensively for the Pacific pocket mouse at 
the Santa Margarita River Mouth in recent years with no success.''
    This statement is borne out by records of recent survey and 
trapping efforts at that locale. Salata (1981) failed to detect the 
Pacific pocket mouse at the Santa Margarita River Mouth on Marine Corps 
Base, Camp Pendleton, in dune, pickleweed/saltgrass, pickleweed, and 
glasswort/upland grassland habitats during a survey effort in March 
1981 that included 188 trap nights. Similarly, the Service (1994a) 
reported no captures of the Pacific pocket mouse from June 1986 
intermittently to August 1990, during a study of the Santa Margarita 
River Mouth that involved a total of 11,380 trap nights and included 
surveys of coastal strand, maritime scrub, salt pan, Salicornia upland, 
Salicornia/Distichlis habitats, and Salicornia plots. Repeated trapping 
bouts at optimum times and in documented Pacific pocket mice habitats 
maximized the possibility of detecting the species. From 1986 to 1987, 
for instance, coastal strand habitats were surveyed in June, May, and 
then again in August for a total of 240 trap nights. In addition, 
potential habitat in maritime scrub, Salicornia upland, Salicornia/
Distichlis dominated areas, and Salicornia plots were surveyed during 
the same calendar months for a total of 2,040 trap nights. Trapping 
bouts in all of the above-mentioned habitats during October of 1986 and 
February of 1987 resulted in additional 1,320 trap nights of survey 
data.
    The Service document referenced by the commenter, a draft proposal 
calling for a live trapping program, is not on letterhead, not dated, 
and not signed by a Service Field Supervisor or person acting on his or 
her behalf. Although the date of the document is unknown, Service staff 
recall that this document has been in the files since at least November 
1991. Thus, this draft document predates the receipt or filing of all 
of the substantive data and scientific papers that were received in 
1993 and 1994.
    Given all of the information that was received in 1993 and the 
additional information and materials that have been received since, the 
Service concludes that sufficient, adequate data are available to 
assess the likely status and distribution of Pacific pocket mice at the 
remaining historic locales and elsewhere throughout its historic range. 
The known present and past status and distribution of the Pacific 
pocket mouse at these historic locales are again individually reviewed 
below in the ``Summary of Factors Affecting the Species'' section of 
this rule.
    Issue 4: The data used by the Service to estimate the remaining 
potential habitat of the Pacific pocket is inadequate. In particular, 
``* * * the Service's data for San Diego County, Oberbauer and 
Vanderwier (1991), turns out, upon inspection, to consist of nothing 
more than unsubstantiated speculation on the part of two individuals.''
    Service Response: The Service considers Oberbauer and Vanderwier's 
(1991) published evaluation of the present, depleted status of 
vegetation communities in San Diego County to be amongst the best 
available scientific information on the subject. Given the data base 
and expertise at the disposal of The Department of Planning and Land 
Use for the County of San Diego, the Service has no reason to doubt the 
validity of the presented data. No data or analysis have been submitted 
to refute their findings. By contrast, the data, analyses, and 
conclusions presented by Soule et al. (1992), summarized by the Service 
(March 30, 1993; 58 FR 16742), and the relevant references cited 
therein are corroborative.
    The Service further concludes that the reported, extreme reduction 
in the potential range and extirpation of the Pacific pocket mouse in 
Los Angeles County is corroborated by a recent assessment of the land 
use status of low-elevation lands therein. In the final rule listing 
the coastal California gnatcatcher (Polioptila californica californica) 
as threatened (March 30, 1993; 58 FR 16742), it was reported that over 
96 percent of the habitat below 250 meters (800 feet) that might have 
supported the gnatcatcher have been largely or entirely developed. 
Although the coastal California gnatcatcher is sympatric with the only 
known, confirmed population of Pacific pocket mouse on the Dana Point 
Headlands (EDAW 1993), the latter species has not been documented above 
approximately 180 meters (600 feet) (Erickson 1993) and apparently does 
not extend nearly as far inland as the former species (summarized March 
30, 1993; 58 FR 16742). Thus, given the intense, almost complete 
development of the immediate coast in Los Angeles County, the Service 
believes that it is reasonable to predict that the past reduction in 
the range of the Pacific pocket mouse there exceeds the corresponding 
reduction in the Los Angeles County range of the coastal California 
gnatcatcher.
    Issue 5: ``The Service should explain that with only 8 known 
historic locations of the PPM and considering the available data on the 
animal, the PPM may never have been abundant in either the number of 
populations in the United States or the number of individuals in those 
populations, at least for the last hundred years.'' In support of this 
position, the commenter also notes that Stephens (1906) described the 
Pacific pocket mouse as ``one of the rarest animals.'' The commenter 
additionally indicates that ``[t]he Service should also explain that 
the PPM may be much more abundant and widespread than suggested in the 
[p]roposed [r]ule.''
    Service Response: Because the Pacific pocket mouse range-wide has 
been variously described as ``exceedingly difficult to catch'' with 
snap traps (von Bloeker 1931a) or ``quite trappable'' once located (R. 
M'Closkey, pers. comm., 1994; P. Meserve, pers. comm., 1994; R. 
MacMillan, pers. comm., 1994), the Service concludes that this anomaly 
is generated as a result of the patchy distribution of the species and 
its ecological requirements (e.g., M'Closkey 1972; Meserve 1976b; P. 
Meserve, pers. comm., 1994; R. M'Closkey, pers. comm., 1994; R. 
MacMillan, pers. comm., 1994; P. Brylski, in litt, 1994). Apparently, 
the ``* * * rareness of the Pacific pocket mouse is not an artifact of 
low trappability * * *'' (P. Brylski, in litt, 1994). Even in an area 
(the San Joaquin Hills) where the Pacific pocket mouse was repeatedly 
located and studied during two research investigations of the ecology 
of the local rodent community, the species was described there as rare 
(M'Closkey 1972) or present in relatively low numbers (P. Meserve, 
pers. comm., 1994).
    Accordingly, given a composite of the available information and 
data, the Service concludes that there are no data, substantive or 
otherwise, that support the hypothesis that the Pacific pocket mouse is 
much more abundant and widespread than suggested in the proposed rule. 
Although the persistence of the Pacific pocket mouse on 45 acres of 
occupied or potentially-occupied habitat (Brylski 1993) suggests the 
real possibility that populations of the species exist elsewhere, 
confirmed extant populations away from the Dana Point Headlands have 
not been found or rediscovered in over 20 years. Thus, given the range-
wide survey data and all other relevant information now available, the 
Service concludes that the Pacific pocket mouse is a patchily 
distributed species that has been described as locally abundant (Bailey 
1939) to rare on carefully studied plots. Further, this mouse has 
become increasingly rare as a result of human-induced, direct impacts 
that are presented and discussed in the ``Summary of Factors Affecting 
the Species'' section of this rule.
    Issue 6: The same commenter observed that ``[t]he Service 
mischaracterizes the threat to the Dana Headlands PPM population 
because the development of the site is not imminent and any threat 
posed by feral or domestic cats cannot be effectively ameliorated by a 
listing; accordingly, the [e]mergency [r]ule is improper.''
    Service Response: The Service acknowledges that the development of 
the Dana Point Headlands currently is not as imminent now as it 
appeared in February of 1994. Since the publishing of the emergency and 
proposed rules, the citizens of Dana Point have forced a referendum on 
the proposed project that apparently will be decided in November of 
1994. The referendum and subsequent possible City of Dana Point actions 
could result in the delayed implementation of, or modifications to, the 
proposed project. The commenter has agreed, however, that ``* * * the 
Dana Headlands site is the only location recently shown to contain 
PPM'' and that the landowners are requesting approval of a specific 
plan that includes ``* * * development on and near the area where the 
PPM was trapped in 1993.''
    The Service disagrees that the documented predation by domestic and 
feral cats cannot be effectively ameliorated by a listing. The mission 
and mandate of the Service is to recover listed species utilizing the 
funds and authority that Congress provides. A recovery plan for the 
Pacific pocket mouse will almost certainly provide for means and 
measures to prevent or reduce the depredation of the species. The 
Service hopes and trusts that it will be able to enlist the cooperation 
of all landowners and cat owners in or near occupied or suspected 
Pacific pocket mouse habitat to prevent the continuing endangerment or 
extinction of the species.
    Issue 7: The same commenter concluded that listing of the Pacific 
pocket mouse is not warranted because a comprehensive survey for the 
species has not been done in Baja California, Mexico.
    Service Response: The Service finds no scientific basis for 
concluding or speculating that a possible population or populations of 
Pacific pocket mice in Mexico preclude the need to list the species. 
Although the range map in Hall (1981) suggests that the range of the 
Pacific pocket mouse may extend into northwestern Baja California, 
Mexico, there are no known records of the species outside of California 
and, thus, the United States as a whole (Hall 1981; Erickson 1993; 
Williams et al. 1993). By contrast, an analysis of species limits maps 
(Hall 1981) and composite of documented records (Hall 1981; Williams et 
al. 1993) reveals that at least 12 small rodent species have been 
historically recorded on the coast of northwestern Baja California in 
San Quintin, Ensenada, or their environs, to wit: Perognathus baileyi, 
Perognathus arenarius, Perognathus fallax, Dipodomys agilis, Dipodomys 
merriami, Dipodomys gravipes, Reithrodontomys megalotis, Onochomys 
torridus, Peromyscus californicus, Peromyscus maniculatus, Microtus 
californicus, and Neotoma fuscipes. Consequently, the best available 
data does not support the conclusion that the Pacific pocket mouse may 
occur in Mexico. Delaying listing until surveys outside of the known 
range had been completed would not be in keeping with the purposes of 
the Act.
    Even if the Pacific pocket mouse occurs in coastal Baja California, 
it is likely that the species does not occur south of 30 deg. north 
latitude, which represents an important transition zone for various 
birds, plants, land mammals, and other animal taxa. If, in an extreme 
case, it is true that the species is patchily distributed southward to 
30 deg. north latitude, the Service, pursuant to analyses and 
subsequent conclusions reached prior to the listing of the coastal 
California gnatcatcher, presently concludes that the United States 
historic distribution of the Pacific pocket mouse would represent a 
significant portion of the species' overall (hypothetical) range (see 
58 FR 16742).
    Issue 8: ``Although the Pacific pocket mouse is not one of the 
identified species in the State's [Natural Communities Conservation 
Planning] program, it may be included in the subregional NCCP for this 
area.'' The County of Orange has been provided with updated habitat 
information and the subregional plan is currently being prepared. 
Therefore, ``* * * the characterization of the NCCP program as 
`inadequate' may be premature.''
    Service Response: The only use of the word ``inadequate'' in the 
proposed or emergency rules (59 FR 5306) refers to the previously 
proposed program to control domestic cat predation on the Dana Point 
Headlands and not to the State's NCCP program. As currently proposed, 
the NCCP program may, in fact, eventually result in the conservation of 
the Pacific pocket mouse or the species' potential habitat. At the 
present time, however, it remains true that Pacific pocket mouse is not 
an NCCP target species and no subregional plans or individual plans 
have been completed or implemented that would provide for the 
protection of the only known, confirmed population or the conservation 
of the species as a whole.
    Issue 9: The proposed relocation of the only confirmed population 
extant is not a viable conservation alternative for the species.
    Service Response: Given the apparent rarity of the Pacific pocket 
mouse and the experimental nature of relocation programs, the Service 
would carefully review any proposal to relocate--in whole or in part--
any population of the Pacific pocket mouse. It remains true that one of 
the central purposes of the Act is to protect the natural habitat of 
the listed species. However, if and when Pacific pocket mouse 
population levels allow, the Service likely will investigate the 
possibility and feasibility of translocating animals to historically-
occupied locales or other areas with suitable habitat and attributes to 
affect the recovery of the species or, in an extreme case, prevent 
extinction. Pursuant to the requirements of the purpose and section 7 
of the Act, the Service likely would solicit the cooperation and 
participation of all Federal agencies and landowners in this regard.
    Issue 10: The listing of the Pacific pocket mouse may be in 
conflict with Federal statutory authority (22 U.S.C. 277d-32) and 
important Federal, international wastewater treatment and flood control 
projects along the Tijuana River that will diminish threats to public 
health and safety.
    Service Response: Several recent surveys conducted in the Tijuana 
River Valley (e.g., U.S. Fish and Wildlife Service 1994b) have not 
resulted in detections of the Pacific pocket mouse. Therefore, given 
the best scientific information available, the listing of the Pacific 
pocket mouse apparently will not conflict with the proposed projects. 
Even if the Pacific pocket mouse is rediscovered in the Tijuana River 
Valley or found elsewhere in Federal project ``action areas,'' as 
defined at 50 CFR 402.02, the Act provides, under prescribed 
circumstances involving public health and safety, for expedited 
emergency consultations.
    Issue 11: The Service must comply with Executive Order No. 12630 
and conduct a takings analysis before reaching any final decision on 
listing the Pacific pocket mouse. The commenter noted that the 
executive order ``* * * requires the preparation and consideration of a 
Takings Implication Assessment (`TIA') by a United States executive 
agency before that agency takes actions which may result in a taking of 
private property for which compensation may be due under the Fifth 
Amendment of the Constitution.''
    Service Response: In accordance with 16 U.S.C. 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 addition of the word ``solely'' was intended 
to remove from the process of the listing or delisting of species any 
factor not related to the biological status of the species. It was 
determined by a congressional committee that economic considerations 
have no relevance to determinations regarding the status of species. 
The application of economic criteria to the analysis of these 
alternatives and to any phase of the species listing process is 
applying economics to the determinations made under section 4 of the 
Act and was specifically rejected by the inclusion of the word 
``solely'' in the legislation (see H.R. Report No. 567, part I, 97th 
Congress, 2d Session 20 [1982]).
    Therefore, the Service concludes that it cannot consider a ``TIA'' 
until a final decision has been made whether or not to list a proposed 
species. However, with the signing and publication of this rule in the 
Federal Register, the Service will complete and consider a TIA.

Summary of Factors Affecting the Species

    After a thorough review and consideration of all available 
information, the Service has determined that the Pacific pocket mouse 
should be classified as an endangered species. Procedures found at 
section 4(a)(1) of the Act (16 U.S.C. 1533) and regulations (50 CFR 
part 424) promulgated to implement the listing provisions of the Act 
were followed. 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 Pacific pocket 
mouse (Perognathus longimembris pacificus) are as follows:
    A. The present or threatened destruction, modification, or 
curtailment of its habitat or range. The Pacific pocket mouse 
historically was recorded and confirmed at eight locales encompassing 
some 29 specific trapping stations or sites (see Erickson 1993). 
Currently, however, the Pacific pocket mouse is known to exist at only 
one site on the Dana Point Headlands, City of Dana Point, Orange 
County, California. Although the Dana Point Headlands have not been 
developed or significantly altered since the Pacific pocket mouse was 
detected at this locale, the ``* * * landowners are requesting approval 
on a specific plan from the City of Dana Point, which plan envisions 
development on and near the area where PPM were trapped in 1993'' (A. 
Hartzell, Attorney-at-Law, in litt, 1994; see also EDAW 1993 and City 
of Dana Point, in litt, 1994).
    The recent status of the Pacific pocket mouse and its habitat has 
been summarized by Erickson (1993) based on a comprehensive search for 
museum specimens and capture records and conversations with pocket mice 
researchers and recognized expert sources. Other records and 
information have been obtained by the Service and made part of the 
public record pertaining to this action. A composite of this 
information is arranged by county and summarized below:
    Los Angeles County. The Pacific pocket mouse historically was 
detected in three areas--Marina del Rey/El Segundo, Wilmington, and 
Clifton. Two of the three historic locales for the Pacific pocket mouse 
(Clifton and Wilmington) in Los Angeles County have been developed 
(Erickson 1993). The Service is unaware of potential Pacific pocket 
mice habitat at these two locales; none was disclosed or revealed as a 
result of the Service's request for information. The third historic 
locale (Marina del Rey/El Segundo) apparently has been substantially 
altered since the species was last detected there (Erickson 1993; P. 
Brylski, in litt, 1993). The Hyperion area, which formerly contained 
relatively large expanses of coastal strand and wetland habitats, has 
been extensively developed. Although potential habitat remains at the 
El Segundo Dunes, walk-over and trapping surveys by J. Maldonado and P. 
Brylski, including a 366-trap-night effort in July of 1993, have caused 
the latter surveyor to conclude that is ``unlikely'' that the Pacific 
pocket mouse occurs there (P. Brylski, in litt, 1993).
    Elsewhere in Los Angeles County, a focused survey for the Pacific 
pocket mouse in Culver City consisting of 600 trap nights over three 
nights in June of 1991 in remnants of appropriate habitat resulted in 
no detections of Pacific pocket mice (P. Kelly, pers. comm., 1994). 
Although patches of suitable habitat apparently remain on the Palos 
Verdes Peninsula and trapping surveys of at least two sites are 
recommended, walk-over surveys of two other areas with suitable habitat 
by P. Brylski and S. Dodd revealed no pocket mouse burrows or diggings 
(P. Brylski, in litt, 1993).
    It remains true that there have been no records of the Pacific 
pocket mouse in Los Angeles County since 1938 (Erickson 1993; see also 
Brylski, in litt, 1993). Given the available information at that time, 
Williams (1986) concluded that it was probable that all populations 
north of the San Joaquin Hills in Orange County were extirpated.
    Orange County. The Pacific pocket mouse has been confirmed at two 
locales in Orange County: the San Joaquin Hills and Dana Point. 
Development of the ``Spyglass Hill'' area in the San Joaquin Hills 
began in 1972 and has resulted in the destruction of the site where the 
Pacific pocket mouse and a number of other small rodent species were 
studied for a three-year period (P. Meserve, pers. comm., 1994; R. 
M'Closkey, pers. comm., 1994; R. MacMillan, pers. comm., 1994; see also 
M'Closkey 1972 and Meserve 1972). Prior to the rediscovery of the 
Pacific pocket mouse in 1993 on the Dana Point Headlands (Brylski 
1993), the last record of the species was from ``Spyglass Hill'' in the 
San Joaquin Hills in 1971 (see Erickson 1993). Recent June to October 
trapping efforts totaling 1197 trap nights in the San Joaquin Hills and 
adjacent Laguna Canyon were unsuccessful in detecting the Pacific 
pocket mouse (Erickson, pers. comm., 1993).
    Elsewhere, extensive, recent small mammal surveys of the coast of 
Orange County away from the Dana Point Headlands have not resulted in 
the detection of the Pacific pocket mouse. For instance, no Pacific 
pocket mice were detected during 54 trapping bouts conducted from 1979 
to 1994 during calendar months from March to October at a total of 24 
different locales in coastal Orange County, including areas in or near 
Corona del Mar, Crystal Cove State Park, Laguna Beach, and San Clemente 
(J. Webb, in litt, 1994). Additional trapping efforts during late fall 
or winter months at some of these same locales resulted in the capture 
of a variety of other native small rodent species but no Pacific pocket 
mice.
    A focused trapping survey of appropriate habitats involving a total 
effort of 558 trap nights during April of 1990 did not result in the 
detection of the Pacific pocket mouse along Aliso Creek (Jones and 
Stokes 1990). R. MacMillan (pers. comm., 1994) also did not detect the 
Pacific pocket mouse during a June, 60-trap night, survey of suitable 
habitat in South Laguna Beach and mentioned that an additional survey 
in Alta Laguna conducted for the City of Laguna Beach was unsuccessful. 
Surveys contributing to a total effort of 1067 trap nights conducted 
elsewhere within the potential Orange County range of the Pacific 
pocket mouse during calendar months from April through November 
resulted in no detections of the species (Erickson, pers. comm., 1993).
    The only known population of the Pacific pocket mouse has persisted 
on the Dana Point Headlands in southern, coastal Orange County. Given 
the data and analysis presented by Brylski (1993), it is apparent that 
25 to 36 Pacific pocket mice occupied approximately 3.75 acres of 
habitat within a coastal sage scrub community at that locale in 1993. 
As is discussed above, this population is located on land that is under 
consideration for development (City of Dana Point, in litt, 1994; EDAW 
1994).
    San Diego County. The Pacific pocket mouse historically has been 
detected at three general locales in San Diego County: the San Onofre 
area, Santa Margarita River Estuary, and the lower Tijuana River 
Valley. Although portions of the San Onofre area are relatively 
undisturbed and deserving of further attention (e.g., P. Brylski, in 
litt, 1994), recent small mammal trapping efforts at the locale failed 
to detect the presence of the Pacific pocket mouse (Erickson 1993; R. 
Erickson, pers. comm., 1993).
    As is reflected in the Service's response to ``Issue 3'' in the 
``Summary of Comments and Recommendations'' section of this rule, 
recent, intense survey efforts at the Santa Margarita River Mouth 
similarly have not resulted in any Pacific pocket mouse detections 
(Salata 1981; U.S. Fish and Wildlife Service 1994a; see also Zembal 
1984). Although the relatively undisturbed coastline of Marine Corps 
Base Camp Pendleton ``* * * probably provides the best chance for the 
survival of the subspecies'' (Erickson 1993), the Base Environmental 
and Natural Resources Management Office has indicated that ``[o]ther 
than the recorded documentation of this species in the vicinity of San 
Onofre and the Santa Margarita Estuary in the 1930's * * * we have no 
information regarding the occurrence of this species aboard Marine 
Corps Base Camp Pendleton. To date, none of the environmental studies 
which have occurred aboard the Base since that time have identified 
this species.'' (L. Armas, in litt, 1994).
    During the 1930's, Camp Pendleton Marine Corps Base did not exist 
and the city of Oceanside was immediately adjacent to the Santa 
Margarita River Estuary. Much of the southern half of the Santa 
Margarita River Estuary was destroyed in the early 1940's during the 
establishment of Marine Corps Base Camp Pendleton and the related 
construction of a boat basin and harbor facilities. In addition, the 
Oceanside area has been extensively developed since the Pacific pocket 
mouse was last recorded there in 1931 and the Service is aware of 
little, if any, remaining suitable habitat in that jurisdiction.
    The lower Tijuana River Valley, which accounts for approximately 35 
percent of all specimen records (Erickson 1993), evidently supported a 
relatively large population of the Pacific pocket mouse in historic 
times (e.g., von Bloeker 1931b). Citing two recent, unsuccessful 
trapping efforts (Taylor and Tiszler 1991; R.T. Miller, pers. comm., 
1993), Erickson (1993) commented that the remaining habitat there is 
possibly insufficient to support the species. Most recently, the U.S. 
Fish and Wildlife Service (1994b) conducted a focused survey for the 
Pacific pocket mouse in the Tijuana River Valley from April 18, 1994 to 
May 13, 1994. Despite walk-over surveys of the area, four or five 
trapping bouts in each of eight separate locales, and a total of 4,242 
trap nights of survey effort, no Pacific pocket mice were detected.
    Elsewhere in San Diego County, a small mammal trapping program that 
began in 1987 is continuing at Torrey Pines State Park in habitats that 
have ranged from maritime chaparral to open (barren) areas as a result 
of two prescribed burns in the project area. Since 1988, 88 traps have 
been set every other week from mid-March to October during the study 
period. Despite an effort that now exceeds 7,500 trap nights, no 
Pacific pocket mice have been detected (R. Dingman, pers. comm., 1994).
    Analysis of the relevant data reveals that the habitat and 
potential range of the Pacific pocket mouse apparently have been 
significantly reduced in the recent past. Opportunities to find 
additional populations of the Pacific pocket mouse apparently are 
limited as a result of the extent of land development in coastal 
southern California (Service files).
    Based on the best available scientific information, the Service 
considers the historic, known range of the Pacific pocket mouse to 
encompass a 3.2-km (2-mile) wide band along the immediate coast of Los 
Angeles, Orange, and San Diego Counties from Marina Del Rey/El Segundo 
south to the international border. Most native habitats within 3 km (2 
miles) of the coast in Los Angeles, Orange and San Diego counties have 
been converted to urban and agricultural uses (Service files).
    Specifically, less than 400 hectares (1,000 acres) or 1 percent of 
approximately 28,000 hectares (69,000 acres) that encompass the 
projected range of the Pacific pocket mouse in Los Angeles County are 
undeveloped (Service files). In Orange County, about 17,600 hectares 
(43,500 acres) or 81 percent of approximately 21,600 hectares (53,500 
acres) encompassing the projected range of the species have been 
developed (Service files). Oberbauer and Vanderwier (1991) reported 
that 72 percent of the original coastal sage scrub, 94 percent of 
native grasslands, 88 percent of coastal mixed chaparral, 88 percent of 
coastal salt marsh, 100 percent of coastal strand, and 92 percent of 
maritime sage scrub habitats in San Diego County had been converted to 
urban and agricultural uses by 1988.
    Although the historic distribution of the coastal sage scrub 
element of Pacific pocket mouse habitat was undoubtedly patchy to some 
degree, this condition evidently has been greatly exacerbated by urban 
and agricultural development. All of the published literature on the 
status of coastal sage scrub vegetation in California supports the 
conclusion that this plant community is one of the most depleted 
habitat types in the United States (Service files). In a broader 
context, the California floristic province, which is recognized as a 
separate evolutionary center by botanists, is identified by Wilson 
(1992) as one of the recognized world ``hot spots,'' which are defined 
to be ``* * * habitats with many species found nowhere else and in 
greatest danger of extinction from human activity.'' The California 
floristic province is the only designated ``hot spot'' in North America 
and Mexico (Wilson 1992).
    The available information further suggests that the quantity of 
potential Pacific pocket mouse river alluvium substrates have 
significantly declined since the species was last recorded in numbers 
in the 1930's. With few exceptions (such as the Santa Margarita River), 
essentially all of the rivers and creeks within its historic range are 
now partially or completely channelized. In many cases (e.g., Los 
Angeles River, San Gabriel River, Santa Ana River) stream and sediment 
flows are regulated or inhibited by dams, reservoirs or other water 
conservation or impoundment facilities (see also Erickson 1993).
    Although some suitable Pacific pocket mouse habitat apparently 
remains in San Onofre and contiguous coast of Marine Corps Base Camp 
Pendleton, the San Joaquin Hills, the Palos Verdes Peninsula, the El 
Segundo Dunes and at scattered locales elsewhere in the historic range 
of the species, this habitat is becoming increasingly scarce and likely 
will continue to be destroyed, disturbed or otherwise impacted as a 
manifest result of human activities. Williams (1986) concluded that 
habitat losses resulting from off-road vehicle activities, highways, 
and urbanization likely were extensive. Erickson (1993) observed that 
industrial and agricultural development likely were additional factors 
contributing to the decline of the species. More recently, the Service 
(1994b) reported that habitats or lands in a historically-occupied 
Pacific pocket mouse locale apparently have been impacted by artificial 
lighting, disking or blading, the presence of non-native rodent species 
(see also Soule et al. 1992), and pedestrian and horse traffic. The 
Pacific pocket mouse, as a representative heteromyid rodent, may be 
more susceptible to the adverse effects of the human presence than 
cricetid rodents (R. MacMillan, pers. comm., 1994).
    Although it is possible that fire may intermittently create or 
sustain Pacific pocket mouse habitat mosaics, it has been reported that 
increased fire frequency may contribute to the type conversion of 
coastal sage scrub to grassland habitats (Service files). In addition, 
the Service acknowledges that the protection of lives and property may 
require fire prevention strategies that do not necessarily result in 
the maintenance or creation of potential Pacific pocket mouse habitat. 
Accordingly, the Service concludes that fire prevention measures and 
unnaturally high fire frequencies resulting from anthropogenic 
ignitions may directly or indirectly impact the Pacific pocket mouse.
    Equally, if not more, problematical than habitat disturbance or 
destruction, however, has been an increasing degree of habitat 
fragmentation in coastal southern California (e.g., Soule et al. 1992; 
Service files), which is known generally to reduce habitat quality and 
promote increased levels of local extinction (e.g., Terborgh and Winter 
1980; Wilcox 1980; Ehrlich and Ehrlich 1981; Wilson 1992; Bolger et al. 
1994 in press). Given the location of the research areas and thrust and 
direction of the investigations, the research and findings of Soule et 
al. (1992) are particularly relevant to a discussion of fragmentation 
effects on the Pacific pocket mouse.
    Based on studies of native bird, rodent and flowering plant species 
persistence in chaparral and coastal sage scrub habitat remnants in 
coastal San Diego County, California, Soule et al. (1992) concluded 
that ``[t]he effects of fragmentation in a scrub habitat in California 
on three taxa (plants, birds, and rodents) are concordant. Extinctions 
within the habitat remnants occur quickly and the sequence of species 
disappearances of birds and rodents is predictable based on population 
density in undisturbed habitat.'' Terborgh and Winter (1980) observed 
previously that ``[r]arity proves to be the best index of 
vulnerability.''
    Bolger et al. (1994, in press) concluded that ``[f]ragments support 
fewer species [of native rodents] than equivalently sized plots in 
large plots of unfragmented chaparral indicating that local extinctions 
have occurred following insularization.'' Given a composite of the 
available data on the local status and distribution of select species 
within the study area in coastal San Diego County, Soule et al. (1992) 
remarked that it was possible to assess with reasonable accuracy the 
date that a particular habitat remnant became isolated.
    Soule et al. (1992) further noted that ``* * * urban barriers 
including highways, streets, and structures, impose a very high degree 
of isolation.'' Similarly, Ehrlich and Ehrlich (1981) observed that 
``smaller animals may also suffer fragmentation of their populations by 
highways, railways, canals, etc., changing population structures and 
making the remaining populations smaller and more subject to random 
extinction. One study has indicated that a four-lane divided highway 
may be a barrier to the movement of small forest mammals equivalent to 
a river twice as wide.'' (Ehrlich and Ehrlich 1981). Although not a 
forest animal, the Pacific pocket mouse must be now considered rare by 
any standard and, therefore, particularly vulnerable to the effects of 
continuing habitat destruction and fragmentation (see Terborgh and 
Winter 1980).
    Largely on the bases of significant habitat loss and fragmentation 
in coastal California, the Service has listed several other species of 
plants and animals as endangered or threatened, including the 
California least tern (Sterna antillarum browni), light-footed clapper 
rail (Rallus longirostris levipes), the Palos Verdes blue butterfly 
(Glaucopsyche lygdamus palosverdesensis), El Segundo blue butterfly 
(Euphilotes battoides allyni), and, most recently, the coastal 
California gnatcatcher (58 FR 16742; Service files). The Service listed 
the coastal California gnatcatcher, because of, in part, the 
significant and ongoing destruction, perturbation, or fragmentation of 
that species' coastal sage scrub habitat (58 FR 16742).
    B. Overutilization for commercial, recreational, scientific, or 
educational purposes. Although the existing information and data are 
not conclusive, P. Brylski (pers. comm., 1994) has commented that 
scientific collecting in the 1930's may have substantially impacted the 
Pacific pocket mouse population in the El Segundo area. Erickson (1993) 
reported the existence of 78 specimens collected in ``Hyperion'' (now 
Marina del Rey/El Segundo) during the fall of 1931 and spring of 1932. 
Otherwise, there is no substantive information that this factor is 
applicable.
    C. Disease or predation. The expressed, perhaps synergistic effects 
of habitat fragmentation and the proximity of urban environments to 
Pacific pocket mouse habitats are likely to increase the rate of 
depredation on that species. Most recently, Soule et al. (1992) has 
confirmed earlier conclusions by noting that ``[t]here is evidence that 
large predators retard the biotic collapse of these [habitat] remnants 
by controlling populations of smaller, semi-commensal predators, 
including domestic cats * * *.''
    Several species have been reported as potential or documented 
predators of the Pacific pocket mouse, including the red fox (Vulpes 
vulpes). The explosive proliferation of non-native populations of red 
foxes in coastal southern California is well documented (e.g., Lewis et 
al., 1993). Given the relative abundance of the red fox in coastal 
southern California (Lewis et al. 1993) and the fact that descriptions 
of the diet of red foxes invariably include mice (Ingles 1965; Jameson 
and Peeters 1988; Burkett and Lewis 1992; Lewis et al. 1993), it seems 
reasonable to assume that ``feral'' foxes similarly could substantially 
impact populations of Pacific pocket mice if and when the species 
overlap. Erickson (1993) has commented that the red fox ``* * * may 
have hastened the demise of pacificus'' in the El Segundo area, a 
locale that previously and historically accommodated the Pacific pocket 
mouse in numbers.
    In addition, feral and domestic cats (Felis catus) are known to be 
formidable predators of native rodents (e.g., Hubbs 1951; George 1974; 
Frank 1992). Pearson (1964) concluded that the removal of 4,200 mice 
from a 14-hectare (35-acre) test plot was accomplished largely by 6 
cats over 8 months.
    Feral or domestic cats are threatening the only known, confirmed 
population of Pacific pocket mouse. Specifically, a resident living 
immediately adjacent to the Dana Point Headlands population reported 
that domestic cats had recently and repeatedly brought in a number of 
``tiny gray mice.'' One such specimen was retrieved and confirmed to be 
a Pacific pocket mouse (P. Brylski, in litt, 1993).
    D. The inadequacy of existing regulatory mechanisms. Should 
protection afforded the Pacific pocket mouse pursuant to the emergency 
rule under the Act (59 FR 5306) lapse or otherwise be removed, other 
select existing regulatory or conservation mechanisms could possibly 
provide some protection for the species. These include--(1) the Act if 
the species were to occur sympatrically with a listed species, (2) the 
California Natural Community Conservation Planning effort, (3) the 
California Environmental Quality Act, (4) land acquisition and 
management by Federal, State, or local agencies or by private groups 
and organizations, and (5) local laws and regulations.
    The Pacific pocket mouse is currently recognized as a Species of 
Special Concern ``Of Highest Priority'' by the California Department of 
Fish and Game. If emergency protection afforded the Pacific pocket 
mouse pursuant to the Act were to be removed prior to the promulgation 
of a final rule listing the species as endangered, the species would 
retain its status as a proposed species under the Act.
    The only known, confirmed population of the Pacific pocket mouse 
does occur sympatrically with a population of the threatened coastal 
California gnatcatcher (Brylski 1993; EDAW 1993). Under provisions of 
section 10(a) of the Act, the Service may permit the incidental take of 
the coastal California gnatcatcher during the course of an otherwise 
legal activity, provided that the species' survival and recovery in the 
wild is not precluded. The issuance of section 10(a) permit to take the 
coastal California gnatcatcher on the Dana Point Headlands could result 
in the extinction of the Pacific pocket mouse.
    In 1991, the State of California commenced the Natural Communities 
Conservation Planning (NCCP) program to address the conservation needs 
of natural ecosystems throughout the State. The initial focus of that 
program is the coastal sage scrub community, which is occupied, in 
part, by the Pacific pocket mouse. At the present time, however, no 
program plans have been completed or implemented, and no protection is 
currently in place or proposed to reduce or eliminate possible, future 
impacts to habitat occupied in 1994 by the Pacific pocket mouse on the 
Dana Point Headlands, which is the only known, confirmed refugium for 
the species.
    In many instances, land-use planning decisions in southern 
California have been made and continue to be made on the basis of 
environmental review documents prepared in accordance with California 
Environmental Quality Act and the National Environmental Policy Act. 
Although impacts to sensitive species and habitats must be disclosed 
pursuant to these statutes, the protection or conservation of the 
species or their habitats are at the discretion of the decision makers. 
Given a composite of the best available scientific information, it is 
clear that these statutes have not adequately protected the Pacific 
pocket mouse or its habitat.
    Prior to the emergency-listing of the Pacific pocket mouse as 
endangered, a relocation program and predator management program were 
proposed to mitigate impacts to the Pacific pocket mouse on the Dana 
Point Headlands (EDAW 1993). More recently, the City of Dana Point 
(City) (in litt, 1994) has indicated that the project applicant must, 
if the Pacific pocket mouse is listed, obtain a take permit for the 
Pacific pocket mouse prior to the issuance of any city permits ``* * * 
that would allow activity that would harm or harass the Pacific pocket 
mouse * * *''
    Because the Service has not received a formal, detailed mitigation 
proposal from the City or project proponent, the Service cannot 
presently assess the merits of said proposal or render a judgment as to 
whether or not the proposed impact avoidance and mitigation measures 
will prevent jeopardy to the Pacific pocket mouse. Although the Service 
notes and appreciates the fact that it would be given the opportunity 
to review the relocation program if the Pocket mouse is not listed 
(City of Dana Point, in litt, 1994), the Service has concluded that the 
potential effects of translocation are not relevant to a decision on 
whether to list a species. Under section 4 of the Act, if data warrant 
listing, the Service must proceed to list the species. The Service (59 
FR 5308) and the California Department of Fish and Game (in litt, 1993) 
both have independently concluded that the relocation program 
previously outlined (EDAW 1993) is inadequate.
    E. Other natural or man-made factors affecting its continued 
existence. Considering the extremely small population size and current 
range of the Pacific pocket mouse (no more than 36 individuals have 
been detected in the last 22 years), the current extent of the coastal 
strand, coastal dune, river alluvium, and coastal sage scrub habitats 
upon which it depends, further losses of habitat will have significant 
adverse effects on any extant populations of this species. Given all 
relevant data and considerations, it is apparent that the species is 
highly susceptible to extinction as a result of environmental or 
demographic factors alone (e.g., Mace and Lande 1991).
    The Service has carefully assessed the best scientific and 
commercial information available regarding the past, present, and 
future threats faced by this species in determining to make this rule 
final. Based on this evaluation, the Service finds that the Pacific 
pocket mouse warrants protection under the Act on the basis of 
continuing threats to the species, which include substantial habitat 
loss and fragmentation and depredation. Therefore, the preferred and 
only possible action is to list the Pacific pocket mouse as endangered, 
which is defined in section 3(6) of the Act as a species ``which is in 
danger of extinction throughout all or a significant portion of its 
range * * *.''
    As provided by 5 U.S.C. 553(d), the Service has determined that 
good cause exists to make the effective date of this rule immediate. 
Delay in implementation of the effective date would place the remaining 
Pacific pocket mice and habitat of the species at risk (see relevant 
discussion below under the heading of ``Critical Habitat'').
    Critical habitat is not being designated at this time for the 
reasons discussed below.

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 is 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 necessary.
    Section 4(a)(3) of the Act, as amended, requires critical habitat 
to be designated to the maximum extent prudent and determinable at the 
time a species is listed as endangered or threatened. The Service has 
concluded that designation of critical habitat is not prudent for the 
Pacific pocket mouse at this time. The Service's 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 species is 
threatened by taking or other human activity, and identification of 
critical habitat can be expected to increase the degree of such threat 
to the species, or (2) such designation of critical habitat would not 
be beneficial to the species.
    In the case of the Pacific pocket mouse, both criteria are met. A 
communication has been received by the Service that effectively 
threatens the only known, confirmed population of the species. This 
threat was received from an individual who was apparently incensed at 
the emergency and proposed listings of the species. On the basis of 
this kind of activity, the Service finds that publication of critical 
habitat descriptions and maps would likely make the species more 
vulnerable to activities prohibited under section 9 of the Act.
    Secondly, the only known, confirmed population of the Pacific 
pocket mouse is found on private property where Federal involvement in 
land-use activities is not expected to occur. Protection resulting from 
critical habitat designation is largely achieved through the Federal 
consultation process pursuant to section 7 of the Act and the 
implementing regulations pertaining thereto (50 CFR 402). Because 
section 7 would not apply to many, if any, of the majority of land-use 
activities occurring within the species' known habitat, its designation 
would not appreciably benefit the species.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Endangered Species 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 local agencies, 
private organizations, 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 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 insure 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 
action may affect a listed species or its critical habitat, the 
responsible Federal agency must enter into formal consultation with the 
Service. Federal agencies that may be involved through activities they 
authorize, fund, or carry out that may affect the Pacific pocket mouse 
or its historical habitat include the Army Corps of Engineers, Federal 
Highway Administration, the Department of the Navy (including Marine 
Corps Base Camp Pendleton).
    The Act and implementing regulations set forth a series of general 
prohibitions and exceptions that apply to all endangered wildlife. The 
prohibitions, codified at 50 CFR 17, 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, or 
collect; or attempt any such conduct), import or export, ship in 
interstate commerce in the course of commercial activity, or sell or 
offer for sale in interstate or foreign commerce any listed species. 
The term ``harm'' as it applies to the take prohibition is defined in 
50 CFR 17.3 to include an act that actually kills or injures listed 
wildlife. Such act may include significant habitat modification or 
degradation where it actually kills or injures listed wildlife by 
significantly impairing essential behavioral patterns, including 
breeding, feeding or sheltering. It also is 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 codified at 50 CFR 17.22, and 17.23. 
Such permits are available for scientific purposes, to enhance the 
propagation or survival of the species, and/or for incidental take in 
connection with otherwise lawful activities.
    Requests for copies of the regulations on listed wildlife and 
inquiries about prohibitions and permits may be addressed to the U.S. 
Fish and Wildlife Service, Permits Branch, 911 N.E. 11th Avenue, 
Portland, Oregon 97232-4181 (telephone 503/231-6241, facsimile 503/231-
6243).

National Environmental Policy Act

    The Fish and Wildlife Service has determined that Environmental 
Assessments and Environmental Impact Statements, 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).

References Cited

    A complete list of all references cited herein is available upon 
request from the U.S. Fish and Wildlife Service, Carlsbad Field Office 
(see ADDRESSES section).

Author

    The primary author of this final rule is Loren R. Hays, U.S. Fish 
and Wildlife Service, Carlsbad Field Office (see ADDRESSES section).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, and Transportation.

Regulation Promulgation

    Accordingly, part 17, subchapter B of chapter I, title 50 of the 
Code of Federal Regulations, is amended 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. Section 17.11(h) is amended by revising and making permanent the 
entry for the ``Mouse, Pacific pocket'' under MAMMALS to read as 
follows:


Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Species                                                 Vertebrate population                                                      
--------------------------------------------------      Historic range        where endangered or       Status     When listed    Critical     Special  
       Common name            Scientific name                                      threatened                                     habitat       rules   
--------------------------------------------------------------------------------------------------------------------------------------------------------
         Mammals                                                                                                                                        
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
Mouse, Pacific pocket...  Perognathus              U.S.A. (CA)............  Entire.................  E                526, 554           NA           NA
                           longimembris pacificus.                                                                                                      
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dated: September 23, 1994.
Mollie H. Beattie,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 94-24065 Filed 9-26-94; 11:01 am]
BILLING CODE 4310-55-P