[Federal Register: February 23, 2000 (Volume 65, Number 36)]
[Rules and Regulations]               
[Page 8881-8890]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AE40

Endangered and Threatened Wildlife and Plants; Final Rule to List 
the Riparian Brush Rabbit and the Riparian, or San Joaquin Valley, 
Woodrat as Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.


SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
endangered status pursuant to the Endangered Species Act of 1973, as 
amended (Act), for the riparian brush rabbit (Sylvilagus bachmani 
riparius) and the riparian or San Joaquin Valley woodrat (Neotoma 
fuscipes riparia). Only a single population of each subspecies has been 
confirmed, in Caswell Memorial State Park (Park), San Joaquin County, 
California. These two subspecies are threatened primarily by flooding, 
wildfire, disease, predation, competition, clearing of riparian 
vegetation, use of rodenticide, and loss of genetic variability. 
Naturally occurring random events increase the risk to the single, 
small population of each subspecies. This rule implements the Federal 
protection and recovery provisions afforded by the Act for these two 

EFFECTIVE DATE: This final rule is effective March 24, 2000.

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, Sacramento Fish and Wildlife Office, 2800 Cottage 
Way, Room W-2606, Sacramento, California 95825.

FOR FURTHER INFORMATION CONTACT: Heather Bell, staff biologist, at the 
U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office 
(see ADDRESSES section), telephone 916/414-6464; facsimile 916/414-



    Even though riparian brush rabbit (Sylvilagus bachmani riparius) 
specimen records and sightings were known from along the San Joaquin 
River near the boundary of San Joaquin and Stanislaus Counties, Orr 
(1935, in Orr 1940) believed, based on the presence of suitable 
habitat, that the species' historical range extended along the 
Sacramento and San Joaquin river systems, from Stanislaus County to the 
Delta region. Historical records for the riparian woodrat (Neotoma 
fuscipes riparia) are similarly distributed along the San Joaquin, 
Stanislaus, and Tuolumne Rivers, and Corral Hollow, in San Joaquin, 
Stanislaus, and Merced Counties (Hooper 1938; Williams 1986). Thus, 
prior to the statewide reduction of riparian communities by nearly 90 
percent (Katibah 1984), the riparian brush rabbit and riparian woodrat 
probably ranged throughout the extensive riparian forests along major 
streams flowing onto the floor of the northern San Joaquin Valley.
    Today only one extant population of each of these subspecies is 
known. The remnant population of each subspecies is in a 104.5 hectare 
(ha) (258 acre (ac)) fragment of riparian forest on the Stanislaus 
River at the Park (Williams 1993) situated on the border of San Joaquin 
and Stanislaus Counties, northwest of Modesto, in the northern San 
Joaquin Valley, California. Upstream and downstream of the Park, some 
original riparian habitat remains on private property. However, the 
fragments are small, isolated, and unlikely to be inhabited by either 
riparian brush rabbits or riparian woodrats. In January of 1997, the 
Park flooded, submerging most of the habitat of these two subspecies. 
Evidence of only three riparian brush rabbits and six riparian woodrats 
was seen immediately following this flooding episode (Daniel F. 
Williams, California State University, Stanislaus, in litt. 1997). In 
1998, only one riparian brush rabbit and nine riparian woodrats were 
live-trapped (D. Williams, in litt. 1998). Other potential threats 
include wildfire, disease, predation, competition, rodenticide use, 
clearing of riparian vegetation, and the loss of genetic variability. 
Naturally occurring events, such as drought and flooding, also increase 
the risk to the single, small population of each subspecies. This rule 
extends the protective provisions under the Act (16 U.S.C. 1531 et 
seq.) to these animals.

Discussion of the Two Subspecies

Riparian Brush Rabbit

    The riparian brush rabbit was described as a distinct subspecies by 
Orr (1935, in Orr 1940) and is one of 13 subspecies of Sylvilagus 
bachmani (Hall 1981), 8 of which occur in California. The specimen from 
which the subspecies designation was described was collected from the 
west side of the San Joaquin River west of Modesto in Stanislaus 
County, California, less than 10 kilometers (km) (6 miles (mi)) from 
the Park. S. bachmani belongs to the order Lagomorpha and family 
Leporidae. The riparian brush rabbit is a medium to small cottontail 
(total length 300 to 375 millimeters (mm) (11.8 to 14.8 inches (in)), 
mass 500 to 800 grams (g) (1.1 to 1.8 pounds (lb)) and is unique in 
that the sides of the rostrum (nasal/upper jaw region of the skull), 
when viewed from above, are noticeably convex instead of straight or 
concave as in other races of S. bachmani (Orr 1940). The color varies 
from dark brown to gray above to white underneath. The subspecies is 
visually similar to the desert cottontail (S. audubonii), which also 
occurs in riparian habitats within the historical distribution of the 
riparian brush rabbit. The riparian brush rabbit can be distinguished 
from the desert cottontail by a smaller, more inconspicuous tail and 
uniformly colored ears (no black tip). However, in-hand identification 
is needed to separate juveniles of these subspecies definitively 
(Williams 1993).
    Breeding of the riparian brush rabbits is restricted to the period 
of female receptivity, approximately January to

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May, putting this subspecies at a competitive disadvantage to the 
desert cottontails outside the Park that breed all year (Mossman 1955; 
Service 1997). After a gestation period of 26 to 30 days, the young are 
born in nest cavities lined mainly with fur and covered with a grass 
plug (Davis 1936; Orr 1940). The young are born naked, blind, and 
helpless and open their eyes in 10 days (Orr 1940). The young rabbits 
remain in the nest about 2 weeks before venturing out, and the female 
will continue to suckle her young 2 to 3 weeks after their birth. Orr 
(1940) reported a mean litter size of 3 to 4, with extremes of 2 to 5, 
while Mossman (1955) reported an average of 4, with a range of 2 to 6. 
Riparian brush rabbits take 4 to 5 months to reach adult size but do 
not reach sexual maturity until the winter following birth. Females 
give birth to about 5 litters per season, averaging an estimated 9 to 
16 young per breeding season (Basey 1990). The percentage of females 
active during the breeding season is unknown, but in one study, 9 of 25 
female adults examined showed no signs of reproductive activity (Basey 
1990). Brush rabbits have relatively small home ranges that usually 
conform to the size and shape of available brushy habitat (Basey 1990). 
In general, the home ranges of males are larger than those of females 
but do not overlap the primary activity centers within female 
territories (Basey 1990). Population estimates from the Park have 
varied from 88 to 452 individuals (Williams 1988), 320 to 540 
individuals (Basey 1990), and 170 to 608 individuals over 81 ha (200.1 
ac) (Williams 1993), but recent flooding in 1997 and 1998 reduced 
numbers severely. In 1997, no riparian brush rabbits were live-trapped, 
one was sighted, and pellets from two others were seen; in 1998, one 
rabbit was live trapped.
    Habitat for the riparian brush rabbit consists of riparian forests 
with a dense understory shrub layer. Forests with a closed canopy, 
however, generally lack sufficient understory of shrubs to meet 
riparian brush rabbits' needs. Brush rabbits frequent small clearings 
where they bask in the sun and feed on a variety of herbaceous 
vegetation, including grasses, sedges, clover, forbs, shoots, and 
leaves. Where mats of low-growing Rosa californica (California wild 
rose) and Rubus vitifolius (Pacific blackberry) occur, the brush 
rabbits live in tunnels that run through the vines and shrubs. Other 
common plants in this riparian forest community are Vitis californica 
(wild grape), Baccharis douglasii (Douglas' coyote bush), and grasses 
(Basey 1990; Williams 1988). Presence of more surface litter and lack 
of willows in the understory signify areas of higher ground that are 
not flooded regularly or heavily (Williams and Basey 1986).
    Brush rabbits are closely tied to cover and usually remain for 
several seconds to minutes just inside dense, brushy cover before 
venturing into the open. They seldom move more than a meter from cover. 
When pursued, they leap back into the cover of shrubs instead of 
heading into open ground (Chapman 1974, in Service 1997). They will not 
cross large, open areas and, therefore, are unable to disperse beyond 
the dense brush of the riparian forest at the Park (Williams 1988). The 
riparian brush rabbit can climb into bushes and trees, though its 
climbing is awkward and limited. This trait probably has significant 
survival value, given that riparian forests are subject to inundation 
by periodic flooding. During periods of heavy flooding, when virtually 
no suitable habitat remains available as refugia, the population has 
dropped dramatically.
    During the flooding of 1976, Park personnel used boats to rescue 
rabbits from bushes. During the flood of 1986, which was short lived, 
it was estimated that all but 10-25 rabbits at the Park were lost (D. 
Williams, in litt. 1997). The population rebounded to 213-312 
individuals by 1993 (Williams 1993), and the Park was considered at 
carrying capacity (the maximum population that a particular environment 
can sustain) under prevailing environmental conditions (following 7 
years of drought). Surveys were conducted in May 1997, after extensive 
winter flooding at the Park, but no riparian brush rabbits were live-
trapped. One brush rabbit was live-trapped in February 1998, following 
a heavy and continuous rainfall.
    Such extraordinarily low population levels subject this subspecies 
to increased genetic risks and naturally occurring random events (see 
discussion in Factor E of the Summary of Factors Affecting the Species 
section of this final rule). Surveys conducted in all potential habitat 
along the Merced, San Joaquin, Stanislaus, and Tuolumne rivers during 
1985 and 1986 failed to locate any additional populations of riparian 
brush rabbits (Williams 1988).
    Because the subspecies was not described until after it is believed 
to have been extirpated from most of its historical range, definitive 
information on its former distribution is lacking. It apparently has 
been extirpated from the Sacramento-San Joaquin River Delta, as well as 
most of the lower San Joaquin River and its tributaries, and the 
Stanislaus, Tuolumne, and Merced rivers (Williams 1986). The range of 
the subspecies probably extended farther upstream than the Merced 
River, assuming that suitable habitat historically occurred along the 
length of the San Joaquin River system (Williams and Basey 1986).

Riparian Woodrat

    The riparian woodrat (Neotoma fuscipes riparia) was first described 
by Hooper (1938), and is one of 11 subspecies of N. fuscipes in the 
family Muridae (order Rodentia). The specimens from which the 
subspecies designation was described were collected about 3 km (2 mi) 
northeast of Vernalis, west of Modesto in Stanislaus County, 
California, approximately 10 km (6 mi) from the Park. Although some 
taxonomic studies of the genus Neotoma have been completed in recent 
years, no further systematic revisions of N. fuscipes have been 
published since Hooper's 1938 report (Hall 1981; Williams 1986; 
Williams 1993). The genetic structure of selected populations of N. 
fuscipes, including N. fuscipes riparia, is currently being examined 
(James Patton, University of California, Berkeley, in litt. 1998). The 
riparian woodrat is a medium-sized rodent, averaging 443 mm (17.4 in) 
in total length, including its 217 mm (8.5 in.) furred tail (Hooper 
1938), and ranges from 200 to 400 g (7.05 to 14.11 ounces (oz)) in 
weight, with marked seasonal variation (Williams et al. 1992; Service 
1997). Neotoma fuscipes riparia differs from other, adjacent subspecies 
of woodrats by being larger, lighter, and more grayish in color, with 
white hind feet instead of dusky on their upper surfaces, and a tail 
more distinctly bicolored (lighter below and darker on top). In 
addition, skull measurements and skull characteristics differ (Hooper 
    The following information is taken from a number of studies on 
Neotoma fuscipes, including N. f. riparia and related subspecies. The 
dusky-footed woodrat lives in loosely cooperative societies and has a 
matrilineal (mother-offspring) social structure. Males are highly 
territorial and aggressive, especially during the breeding season when 
they will mate with more than one female (Kelly 1990, in Service 1997). 
Females have 1 to 5 litters per year with 3 to 4 young in each litter. 
Reproduction occurs in all months, with the fewest pregnancies in 
December and the most in February. Numbers of juveniles appearing 
outside the nest is greatest in July and least in January and February 
(Williams et al. 1992). The young are born in stick nest houses, or

[[Page 8883]]

lodges, on the ground, which measure 0.6 to 0.9 meters (m) (2 to 3 feet 
(ft)) high and 1.2 to 1.8 m (4 to 6 ft) in diameter. Most houses are 
positioned over or against logs (Cook 1992). Unoccupied houses can 
persist 20-30 years (Linsdale and Tevis 1951, in Service 1998) if not 
destroyed by flooding (D. Williams, pers. comm. 1998). Unlike other 
subspecies, the riparian woodrat occasionally builds nests in cavities 
in trees and in artificial wood duck nest boxes (Williams 1986). Nest 
houses typically are occupied by an individual adult. Unlike males, 
females remain in or near natal areas (birthplace) throughout their 
life (Williams et al. 1992). At the Park, Williams (1993) reported a 
mean density of 8.32 houses per hectare (ha) (20.55 houses per acre 
(ac)), or 757 houses on 91 ha (225 ac) of suitable habitat; occupancy 
was not verified. In a study of another subspecies of N. fuscipes, 
Linsdale and Tevis (1951, in Service 1998) found that 70 percent of the 
population survived less than 1 year, 27 percent survived 2 years, and 
3 percent survived 3 years or more. Williams et al. (1992) also cited a 
number of studies that indicated woodrats are highly responsive to 
habitat alteration, with populations fluctuating widely in response to 
a variety of natural or manmade factors, such as fire, flood, drought, 
habitat modification, and browsing and trampling by ungulates. Cook 
(1992) estimated the Park population at 637 woodrats over 102 ha (252 
ac) of habitat. Williams (1993) estimated a peak population at Caswell 
of 437 animals, based on mean density of 4.8 woodrats per ha on 91 ha 
(225 ac) of suitable habitat. A woodrat population was reported from 
the early 1970s near the type locality at Vernalis, but the current 
status of the population is unknown (Williams 1986). Between April 1, 
1997, and March 20, 1998, 15 riparian woodrats were live-trapped at the 
Park (D. Williams in litt. 1998).
    Riparian woodrats are common where there are deciduous valley oaks 
but few live oaks. Riparian woodrats are most numerous where shrub 
cover is dense and least abundant in open areas. In riparian areas, 
highest densities of woodrats and their houses are often encountered in 
willow thickets with an oak overstory (Linsdale and Tevis 1951, in 
Service 1998). Mostly active at night, the woodrat's diet is diverse 
and principally herbivorous, with leaves, fruits, terminal shoots of 
twigs, flowers, nuts, and fungi comprising the bulk of ingested 
material (Williams et al. 1992).
    The range of the riparian woodrat is far more restricted today than 
it was in 1938 (Williams 1986). The only verified population is 
restricted to about 102 ha (252 ac) of riparian forest at the Park on 
the Stanislaus River. Loss, fragmentation, and degradation of habitat 
are the principal reasons for the decline of the riparian woodrat 
(Service 1997). The most immediate threats include flooding of Park 
lands and wildfires. Because the riparian woodrat is able to climb 
trees more easily than the brush rabbit, the woodrat may not be 
directly affected by flooding to the degree the riparian brush rabbit 
is. Woodrat houses, which are essential to survival, can, however, be 
severely impacted by flooding, thus affecting the viability of the 
population. Wildfires are of concern because of the potential for 
severe degradation of habitat and the loss of individuals unable to 
escape the fire. In addition to the threat of random natural events 
such as flooding and fire, the riparian woodrat is also prone to the 
effects of ongoing threats such as disease, predation, and potential 
competition with the exotic black rat (Rattus rattus) (D. Williams, in 
litt. 1998; D. Williams, pers. comm. 1998). No specific conservation 
measures for the riparian woodrat are in place, but the species does 
receive some protection through the management plan for the riparian 
brush rabbit at the Park. The California Department of Parks and 
Recreation has supported some general small-mammal studies and woodrat 
population studies at the Park (Cook 1992; Williams 1993).
    Today, riparian communities of the lower San Joaquin River and its 
tributaries outside the Park have virtually been eliminated. The 
remaining habitat patches are small, narrow fragments confined within 
levees. The placement of these levees has eliminated the natural 
floodplain of the Stanislaus River, increasing the severity of the 
flooding that occurs within the confines of the levees. Therefore, the 
Park, which is on the river side of the levees, is prone to flood 
completely during major storms or heavy flow releases from New Melones 
dam (D. Williams, pers. comm. 1998). Because remaining riparian forests 
are small, isolated, and vulnerable to major flood events (Williams and 
Basey 1986), whether they can support viable populations of these 
subspecies over the long-term is questionable. Historical habitat and 
refugia from flooding in surrounding lands are now unsuitable for these 
subspecies, as these lands consist primarily of cultivated fields, 
orchards, and vineyards (Williams and Basey 1986). Wildfire, flooding, 
brush clearing, predation, competition, disease, and use of 
rodenticides imperil the continued existence of these two subspecies in 
their last known population center.

Previous Federal Action

    Federal action on these two subspecies began on September 18, 1985, 
when we published the Vertebrate Wildlife Notice of Review (50 FR 
37958), which included the riparian brush rabbit and riparian woodrat 
as category 2 candidate species. Category 2 candidates, a designation 
discontinued in a Notice of Review published by us on February 28, 1996 
(61 FR 7596), were taxa for which we had information in our possession 
indicating that proposing to list as endangered or threatened was 
possibly appropriate, but for which conclusive data on biological 
vulnerability and threats were not currently available. In the January 
6, 1989, Animal Notice of Review (54 FR 554), we elevated the riparian 
brush rabbit to a category 1 candidate species as a result of more 
intensive field work by Williams and Basey (1986) that identified only 
a single remaining population of this subspecies. Category 1 taxa were 
those for which we had substantial information on biological 
vulnerability and threats to support preparation of listing proposals. 
We retained the riparian brush rabbit as a category 1 candidate and 
elevated the status of the riparian woodrat to category 1 in the 
November 21, 1991, Animal Notice of Review (56 FR 58804). This change 
was based on a re-evaluation of the information contained in the study 
conducted by Williams and Basey (1986). The November 15, 1994, Animal 
Notice of Review (59 FR 58987) included both subspecies in category 1. 
Upon publication of the February 28, 1996 combined Animal and Plant 
Notice of Review (61 FR 7596), we ceased using category designations 
and included both subspecies as candidates. Candidate species are those 
for which we have on file sufficient information on biological 
vulnerability and threats to support proposals to list the species as 
threatened or endangered. Candidate status for these animals was 
continued in the September 19, 1997, Notice of Review (62 FR 49398).
    Based on the decline in numbers of both these subspecies as 
identified during the live-trapping surveys of 1997 (D. Williams, in 
litt. 1997) and the threats to their continued existence, the riparian 
brush rabbit and riparian woodrat were proposed for listing as 
endangered on November 21, 1997 (62 FR 62276).
    The processing of this final rule conforms with our Listing 

[[Page 8884]]

Guidance published in the Federal Register on October 22, 1999 (64 FR 
57114). The guidance clarifies the order in which we will process 
rulemakings. Highest priority is processing emergency listing rules for 
any species determined to face a significant and imminent risk to its 
well-being (Priority 1). Second priority (Priority 2) is processing 
final determinations on proposed additions to the lists of endangered 
and threatened wildlife and plants. Third priority is processing new 
proposals to add species to the lists. The processing of administrative 
petition findings (petitions filed under section 4 of the Act) is the 
fourth priority. The processing of critical habitat determinations 
(prudency and determinability decisions) and proposed or final 
designations of critical habitat will no longer be subject to 
prioritization under the Listing Priority Guidance. This final rule is 
a Priority 2 action and is being completed in accordance with the 
current Listing Priority Guidance. We have updated this rule to reflect 
any changes in information concerning distribution, status, and threats 
since the publication of the proposed rule. This additional information 
did not alter our decision to list the two subspecies.

Summary of Comments and Recommendations

    In the proposed rule published November 21, 1997 (62 FR 62276), we 
requested that all interested parties submit factual reports or 
information that might contribute to the development of a final rule 
for the riparian brush rabbit and the riparian woodrat. The public 
comment period closed on January 21, 1998. We contacted appropriate 
State agencies, county and city governments, Federal agencies, 
scientific organizations, and other interested parties and requested 
comments. We published a newspaper notice in The Modesto Bee on January 
20, 1998, which invited general public comment. Given the flood events 
of 1997 and 1998, on April 13, 1998, the public comment period was 
reopened (63 FR 17981) to consider any new survey information or other 
new information prior to making the final status determinations. This 
comment period ended May 28, 1998.
    We received 11 comments concerning the proposed rule during the 
comment period, from a total of 10 commenters. Some commenters 
submitted more than one comment to us. Six commenters supported the 
listing; four commenters were neutral. No commenters opposed the 
proposed listing. Several commenters provided additional information 
that, along with other clarifications, has been incorporated into the 
``'Background''' or ``'Summary of Factors Affecting the Species''' 
sections of this final rule. Comments have been organized into specific 
issues. These issues and our responses are summarized as follows:
    Issue 1: Two commenters expressed concern that the area around the 
Park should be protected from further urban development.
    Our Response: Habitat protection afforded by the Act (under section 
7) to species listed as threatened or endangered requires Federal 
agencies to consult with us on any action that is funded, authorized, 
or carried out by a Federal agency. The concerns for the subspecies 
will be addressed and measures may be implemented to ensure that the 
proposed action will not jeopardize the continued existence of either 
the riparian brush rabbit or the riparian woodrat. For detailed 
discussions of the section 7 consultation process, see the Available 
Conservation Measures section of this final rule. In addition, once the 
subspecies are listed, a recovery plan (or plans) is drafted (for a 
discussion of the recovery planning process, see the Available 
Conservation Measures section of this final rule).
    Issue 2: The Department of Parks and Recreation, which owns and 
manages the Park, was concerned about restrictions the listing of these 
two subspecies may have on the recreational and maintenance activities 
at the Park.
    Our Response: We recognize these concerns and anticipate continuing 
to work closely with the Department of Parks and Recreation and staff 
at the Park in furthering protective measures, many of which have 
already been voluntarily implemented. We are confident that the 
protection and recovery of these two subspecies will be compatible with 
recreational and maintenance activities at the Park.

Peer Review

    In accordance with our Interagency Cooperative Policy for Peer 
Review published on July 1, 1994 (59 FR 34270), we solicited the expert 
opinions of four independent and appropriate specialists regarding 
review of pertinent scientific or commercial data and issues relating 
to the taxonomy, population models, and supportive biological and 
ecological information for the riparian brush rabbit and the riparian 
    We received comments from two of the four requested peer reviewers. 
Both reviewers stated that the proposed rule contained an accurate 
summary of the natural history, current status, and current threats to 
survival of the two subspecies and that listing was warranted. One 
reviewer was concerned that the listing may be too late to prevent 
extinction by natural factors alone. The other reviewer suggested 
clarifications or changes within the text. The reviewer suggests that 
(1) low population numbers of the brush rabbit clearly make it 
extremely vulnerable to detrimental genetic processes and random 
events, while the proposed rule suggested such populations may be only 
somewhat vulnerable; (2) decreased survivorship of young is the best 
known of the effects of inbreeding (deleterious genes). Inbreeding 
actually reduces all of the following: fecundity, juvenile 
survivorship, and adult lifespan; and (3) the reviewer provided a 
reference to a new study by Saccheri et al. (1998) that states ``* * * 
inbreeding can contribute significantly to the extinction of wild 
populations' (Katherine Ralls, Smithsonian Institution, in litt. 1998). 
Information and suggestions provided by the reviewers have been taken 
into consideration during the development of this final rule and 
incorporated where appropriate.

Summary of Factors Affecting the Species

    Section 4 of the Act and regulations (50 CFR part 424) that 
implement the listing provisions of the Act set forth the procedures 
for adding species to the Federal lists of endangered and threatened 
species. We determine if a species is endangered or threatened due to 
one or more of the five factors described in section 4(a)(1) of the 
Act. These factors and how we applied them to the riparian brush rabbit 
and to the riparian woodrat are as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Their Habitat or Range

    Sylvilagus bachmani riparius and Neotoma fuscipes riparia inhabit 
riparian forest communities, and both apparently have been extirpated 
from their entire historical range except for a single known population 
of each along the Stanislaus River. Katibah (1984) estimated that only 
41,300 ha (102,052 ac) remain of an estimated 373,000 ha (921,170 ac) 
of presettlement riparian forest in California's Central Valley, a 
reduction of 89 percent. He attributed the loss and modification of 
riparian forests along valley floor river systems to urban, commercial, 
and agricultural development; wood cutting; reclamation and flood 
control activities; groundwater pumping; river channelization; dam 
construction; and water diversions (Katibah 1984).

[[Page 8885]]

    Several land use practices and related human activities contributed 
to the decline of the riparian brush rabbit and riparian woodrat 
throughout their historical ranges. During the past 10 to 20 years, 
cultivation has expanded along the floodplain of the main tributaries 
of the lower San Joaquin River system (Basey 1990). Increased habitat 
conversion to agricultural uses has resulted from the recent 
construction of the following dams on tributaries that individually and 
collectively have altered the timing, frequency, duration, and 
intensity of flooding--Exchequer Dam on the Merced River, New Melones 
Dam on the Stanislaus River, and New Don Pedro Dam on the Tuolumne 
River. Before these dams and flood control projects (levees) were 
constructed, much of the natural floodplain was used as pasture land 
for livestock grazing (Basey 1990). Uneven topography in these areas, 
before the dams were constructed, provided escape cover because some 
land remained above typical flood levels and contained patches of 
shrubs and trees for cover. Such sites likely provided refuge from 
flooding for these subspecies. Williams and Basey (1986) state that ``* 
* * virtually all areas outside of flood control levees now have been 
cleared, leveled, and planted to orchards, vineyards, or annual row 
crops.'' Conversion from pasture to cultivated fields also eliminated 
hedgerows and other residual patches of cover that provided travel 
corridors and refuge sites for the two subspecies. The severity of 
flooding likely increased as the habitat for these two subspecies was 
incorporated by flood control levees. The effects of catastrophic 
flooding are discussed further under Factor E of this section.
    Although brush clearing adversely affected the habitat of the 
riparian brush rabbit and the riparian woodrat populations at the Park 
in the mid-1980s (Williams 1986), these populations are no longer 
directly threatened by brush clearing, tree cutting, or the conversion 
of land to agricultural uses. Because the only known populations of 
these subspecies occur within the boundaries of the Park, such 
activities outside of Park boundaries do not currently pose a direct 
threat to either subspecies. Such activities continue, however, to 
eliminate and fragment patches of remnant habitat within the historical 
range of these subspecies.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Overutilization is not known to be a threat to either subspecies. 
However, the very small population at the remaining site makes the 
riparian brush rabbit vulnerable to extinction from unauthorized 
recreational hunting and collection for scientific or other purposes. 
The brush rabbit (Sylvilagus bachmani) is designated as a resident 
small game species in California and is hunted from July 1 through 
January 30 with a daily bag limit of five animals (Williams and Basey 
1986). Hunting regulations set by the California Fish and Game 
Commission do not distinguish the riparian brush rabbit from other 
subspecies of S. bachmani. Therefore, riparian brush rabbits that 
disperse beyond the boundaries of the Park (as they may, especially 
during times of flooding) face the potential threat of being hunted.

C. Disease or Predation

    Like most rabbits, the riparian brush rabbit is subject to a 
variety of common diseases, including tularemia, plague, encephalitis, 
and brucellosis. These contagious, and generally fatal, diseases could 
be transmitted easily to riparian brush rabbits from neighboring 
populations of desert cottontails (Williams 1988). A suspected outbreak 
of plague in 1966-67 decimated woodrat populations in foothills of the 
southern Sierra Nevada, the Tehachapi Mountains, and the Coast Range 
(Murray and Barnes 1969, in Williams et al. 1992). The small population 
size and restricted distribution of both the riparian brush rabbit and 
riparian woodrat increase their vulnerability to epidemic diseases. 
However, the significance of the threat of disease to the riparian 
brush rabbit and riparian woodrat is not known.
    Coyotes (Canis latrans), gray foxes (Vulpes cinereoargenteus), 
long-tailed weasels (Mustela frenata), raccoons (Procyon lotor), feral 
domestic cats (Felis catus) and dogs (Canis familiaris), hawks 
(Accipitridae), and owls (Strigidae) are known predators of brush 
rabbits and woodrats (Orr 1940; Williams 1988). At currently depleted 
population levels, any predation could substantially affect the 
survival of these two subspecies.

D. The Inadequacy of Existing Regulatory Mechanisms

    Section 404 of the Clean Water Act (CWA) is a Federal law that 
potentially affords some attention and protection for these subspecies. 
However, brush clearing, tree cutting, and the conversion of riparian 
habitat to agricultural uses, all of which adversely affect both 
subspecies, are generally unregulated, and this law does not provide 
protection from these activities. For example, pursuant to 33 CFR 
323.4, the U.S. Army Corps of Engineers (Corps) has promulgated 
regulations that exempt some farming, forestry, and maintenance 
activities from the regulatory requirements of section 404. Although 
the Corps administers flowage (flooding) and restoration easements 
along the lower reaches of the Stanislaus River, the difficulty of 
enforcing the conditions of the easements and inadequate funding for 
restoration impedes appropriate habitat restoration activities.
    The California Department of Parks and Recreation developed a 
riparian brush rabbit management plan for the Park (Williams 1988). 
This management plan provides some measure of protection to the 
riparian brush rabbit population and incidental protection for the 
riparian woodrat. Despite the existence of a management plan, both the 
riparian brush rabbit and riparian woodrat remain vulnerable to threats 
and hazards originating outside of the Park as well as threats that 
continue within the Park's boundaries (see Factor E below).
    Under the California Environmental Quality Act (CEQA) (Public 
Resources Code Secs. 21000-21177), full disclosure of the potential 
environmental impacts of proposed projects is required. The public 
agency with primary authority or jurisdiction over the project is 
designated as the lead agency and is responsible for conducting a 
review of the project and consulting with the other agencies concerned 
with the resources affected by the project. Section 15065 of the 
guidelines that guide CEQA implementation requires a finding of 
significance if a project has the potential to ``reduce the number or 
restrict the range of a rare or endangered plant or animal.'' Species 
that are eligible for listing as rare, threatened, or endangered but 
are not so listed are given the same protection as those species that 
are officially listed with the State. However, once significant effects 
are identified, the lead agency has the option to require mitigation 
for effects through changes in the project or to decide that overriding 
considerations, such as overriding social or economic considerations, 
make mitigation infeasible (CEQA Sec. 21002). In the latter case, 
projects may be approved that cause significant environmental damage, 
such as destruction of endangered species, their habitat, or

[[Page 8886]]

their continued existence. Protection of listed species through CEQA 
is, therefore, dependent upon the discretion of the agency involved.
    The California Endangered Species Act (CESA) affords the riparian 
brush rabbit some conservation benefits. The State of California listed 
the riparian brush rabbit as an endangered species in May 1994. 
Although the CESA provides a measure of protection to the subspecies, 
resulting in the formulation of mitigation measures to reduce or offset 
impacts for any projects proposed in riparian brush rabbit habitat, 
this law has not adequately prevented the ongoing loss of riparian 
forest. Riparian forests outside of the Park are important for recovery 
implementation to succeed, as neither the riparian brush rabbit nor the 
riparian woodrat can be recovered on Park lands alone (Service 1997).

E. Other Natural or Manmade Factors Affecting its Continued Existence

    Small, isolated populations are especially at risk from random 
events as there is little or no possibility of recolonization if the 
random event, whether natural or manmade, affects the entire 
population. Random events that may be catastrophic to the riparian 
brush rabbit or the riparian woodrat include the threat of wildfire, 
severe flooding, and prolonged drought. Although the Park initiated a 
fire management plan to reduce fuel load and create firebreaks in an 
effort to protect habitat, the threat of fires originating outside of 
the Park boundaries and accidentally within the Park boundaries from 
recreational activities still exists. Wildfire exposes the riparian 
brush rabbit and the riparian woodrat to habitat destruction and death 
(Basey 1990). The brushy areas most vulnerable to fire also are 
important areas of habitat for riparian brush rabbits and riparian 
woodrats (Basey 1990). Between 1975 and 1987, 10 wildfires were 
reported within the Park. After 0.2 ha (0.5 ac) were burned in 1981, no 
evidence of brush rabbits was found in the area (Basey 1990). Fire is 
known to kill other species of woodrats, such as the closely related 
dusky-footed woodrat (Neotoma fuscipes), and thus presumably poses the 
same threat to the riparian woodrat. After a fire burned a canyon 
bottom dominated by oaks and sycamores in south-coastal California, 
Chew et al. (1959, in Williams et al. 1992) found 16 dead dusky-footed 
woodrats per acre.
    Although flooding of low-lying riparian forests is a naturally 
occurring event, the changes to the river systems which began around 
the 1940s have altered natural flooding and its frequency, timing, and 
severity, due to manmade levees, dams, and water diversions. The 
Stanislaus River, for example, has manmade levees built to keep high 
flows channelized and dams upstream for flood control and water 
storage. The riparian habitat at the Park is confined entirely within 
levees, offering little protection from flooding during periods of high 
stream flow that routinely occur during the wet winter season. Major 
flooding likely drowns riparian brush rabbits and riparian woodrats, 
eliminates foraging habitat and shelter for prolonged periods, and 
exposes brush rabbits and woodrats to increased predation by stranding 
them in trees or on high ground where there is little or no cover 
(Nolan 1984, in Service 1997). Ironically the levees themselves now 
function as high ground during flooding events.
    Surveys have confirmed that after major flooding events the numbers 
of riparian brush rabbits and riparian woodrats decrease, sometimes 
dramatically. Basey (1990) concluded, based on visual sightings and 
pellet surveys, that the riparian brush rabbit population may have been 
reduced to fewer than 15 to 20 individuals during flooding in 1983. 
Only about 3.6 ha (9 ac) in five small areas of the 104.5 ha (258 ac) 
Park showed regular use by brush rabbits in the summer of 1986 after 
floods in February and March of that year (Williams 1988). Williams 
(1986) found that riparian brush rabbits sometimes gain temporary 
shelter from floods by climbing trees, but he estimated that only 10 or 
fewer individual rabbits survived the severe winter flooding in 1985-86 
(Williams 1988).
    The floods of January 1997 left about 85 percent of the Park under 
0.6-3.0 m (2-10 ft) or more of water in most areas for at least 2 weeks 
and, in lower areas, for as long as 7 weeks. Efforts in January to 
locate and potentially rescue stranded riparian brush rabbits resulted 
in the observation of only a single rabbit pellet (D. Williams, in 
litt. 1997). In areas of the Park searched visually in March 1997, no 
rabbits or pellets were found, although searchers did find two mounds 
containing fresh grass. Such mounds or ``forms'' are typically made by 
rabbits. In April 1997, searchers documented two rabbit fecal pellets 
but found no other sign of rabbits or woodrat activity. Trapping 
surveys were initiated in early May, well after floodwaters had 
receded, in hopes that any surviving rabbits would be located. During 
22 nights of trapping, no rabbits were caught, one rabbit was visually 
sighted, and at another location, fresh rabbit tracks were found (D. 
Williams, in litt. 1997).
    The riparian woodrat also is vulnerable to flooding events, 
although its ability to nest in trees and wood duck nest boxes 
(Williams 1993) suggests some ability to avoid the negative effects of 
flooding. Nonetheless, the large majority of woodrat nests occur on the 
ground (Williams 1993). After the January 1997 floods inundated the 
Park for 2 to 7 weeks, trapping and survey efforts in May 1997 resulted 
in the capture of only eight woodrats (D. Williams, in litt. 1997). 
Trapping efforts of similar intensity in 1993 resulted in the capture 
of 57 woodrats (D. Williams, in litt. 1997). Severe flooding could 
eliminate the Park populations of both the riparian brush rabbit and 
the riparian woodrat and result in the extinction of these subspecies. 
Flooding is also likely to increase competition between riparian brush 
rabbits and desert cottontails, a subspecies that occurs in a wider 
range of habitats, including riparian zones, within the same geographic 
area (Basey 1990). Riparian brush rabbits cannot return to their home 
areas if displaced more than about 340 m (1,115.5 ft) (Chapman 1971, in 
Basey 1990). Desert cottontails, in contrast, may return home when 
displaced as much as 4.8 km (3 mi) (Bowers 1954, in Basey 1990). 
Therefore, if displaced by flooding more than about 340 m (1,115.5 ft) 
from their home areas, riparian brush rabbits may be stranded in 
habitats where desert cottontails have a competitive advantage.
    Drought may decrease the carrying capacity of riparian forest 
habitat for the riparian brush rabbit and the riparian woodrat. By 
1993, following seven years of drought, riparian forest habitat at the 
Park was considered to be at carrying capacity for the riparian brush 
rabbit (Williams 1993). Depressed population densities of woodrats have 
been reported due to drought (Linsdale and Tevis 1951, in Service 
1998). Because riparian forest habitat at the Park is an isolated area 
of habitat, decreased carrying capacity may affect the populations of 
riparian brush rabbits and riparian woodrats because more individuals 
compete for the same resources, such as food and shelter. In some 
mammals, long periods of drought and increased competition among 
individuals can affect individual survivorship and reproductive success 
(Service 1997). Surveys to determine the effects of prolonged drought 
on the carrying capacity of Park habitat for the riparian woodrat, 
however, have not been conducted.

[[Page 8887]]

    Other factors that are a concern are the use of rodenticides in 
areas outside of the Park (rodenticides are no longer applied in Park 
habitat) and competition from exotic or invading species, such as the 
desert cottontail or the black rat, which may compete with the riparian 
brush rabbit or the riparian woodrat, respectively (Service 1997). 
Additionally, the extent to which recreational activities such as 
vehicular and pedestrian traffic and predation by domestic dogs and 
cats may affect these subspecies has not been studied. With severely 
low populations of both subspecies, these activities may have a 
significant effect on their survival.
    The population numbers of both subspecies are now sufficiently low 
that the effects of inbreeding are highly likely to result in the 
expression of deleterious genes in the population (i.e., inbreeding 
depression) (Gilpin 1987; K. Ralls, in litt. 1998). Such deleterious 
genes can reduce individual fitness in various ways, including 
decreased survivorship of young, reduced fecundity (reproductive 
capacity), and reduced adult lifespan (K. Ralls, in litt. 1998). Small 
populations are also at greater risk from the effects of genetic drift, 
a decrease in genetic variability due to random changes in gene 
frequency from one generation to the next. This reduction of 
variability within a population limits the ability of that population 
to respond to environmental changes.
    Presently, a multispecies habitat conservation plan (HCP) is being 
developed for San Joaquin County, California. The riparian brush rabbit 
and riparian woodrat will be considered in this HCP, and some 
conservation measures that will likely minimize adverse impacts and/or 
benefit these two subspecies. A draft HCP will be available for public 
review in the future. Until the HCP is released for public comment, we 
cannot determine how the HCP will affect these two subspecies.
    In developing this final rule, we have carefully assessed the best 
scientific and commercial information available regarding the past, 
present, and future threats faced by these subspecies. Based on this 
evaluation, the preferred action is to list the riparian brush rabbit 
and the riparian woodrat as endangered. The small population size and 
single locality of these two subspecies render them extremely 
vulnerable to a wide array of threats. These subspecies currently face 
immediate threats from wildfire, flooding events, and drought. In 
addition, they face threats from habitat destruction, competition, 
predation, and the use of rodenticides. The riparian forest is reduced 
along the San Joaquin River system to the point that the few remaining 
habitat remnants outside of the Park are small and isolated and cannot 
support viable populations of these subspecies that can persist over 
time. Thus, even in the event that the few remaining unsurveyed 
fragments of habitat do support these subspecies, the recommended 
listing status of the riparian brush rabbit and riparian woodrat would 
not change and their listing as endangered would be warranted. 
Projected increases in human population within the San Joaquin Valley 
and pressures associated with urban development, as well as the 
inadequacy of existing regulatory mechanisms, suggest action is needed 
to successfully recover the riparian brush rabbit and the riparian 
woodrat. Threatened status is not appropriate for either subspecies, 
considering the extent of loss and degradation of their habitat and the 
vulnerability of the remaining population.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as 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 essential to the conservation of the 
species and that may require special management considerations or 
protection; and specific areas outside the geographical area occupied 
by the species at the time it is listed, upon 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.
    In the proposed rule, we indicated that designation of critical 
habitat was not prudent for the riparian brush rabbit and riparian 
woodrat because we believed it would not provide any additional benefit 
beyond that provided through listing as endangered since the species 
are only found within the State park.
    In the last few years, a series of court decisions have overturned 
Service determinations regarding a variety of species that designation 
of critical habitat would not be prudent (e.g., Natural Resources 
Defense Council v. U.S. Department of the Interior 113 F. 3d 1121 (9th 
Cir. 1997); Conservation Council for Hawaii v. Babbitt, 2 F. Supp. 2d 
1280 (D. Hawaii 1998)). Based on the standards applied in those 
judicial opinions, we have reexamined the question of whether critical 
habitat for the riparian brush rabbit and riparian woodrat would be 
    In the absence of a finding that critical habitat would increase 
threats to a species, if there are any benefits to critical habitat 
designation, then a prudent finding is warranted. In the case of these 
species, there may be some benefits to designation of critical habitat. 
The primary regulatory effect of critical habitat is the section 7 
requirement that Federal agencies refrain from taking any action that 
destroys or adversely modifies critical habitat. While a critical 
habitat designation for habitat currently occupied by these species 
would not be likely to change the section 7 consultation outcome 
because an action that destroys or adversely modifies such critical 
habitat would also be likely to result in jeopardy to the species, 
there may be instances where section 7 consultation would be triggered 
only if critical habitat is designated. Examples could include 
unoccupied habitat or occupied habitat that may become unoccupied in 
the future. There may also be some educational or informational 
benefits to designating critical habitat. Therefore, we find that 
critical habitat is prudent for the riparian brush rabbit and riparian 
    The Final Listing Priority Guidance for FY 2000 (64 FR 57114) 
states that the processing of critical habitat determinations (prudency 
and determinability decisions) and proposed or final designations of 
critical habitat will no longer be subject to prioritization under the 
Listing Priority Guidance. Critical habitat determinations, which were 
previously included in final listing rules published in the Federal 
Register, may now be processed separately, in which case stand-alone 
critical habitat determinations will be published as notices in the 
Federal Register. We will undertake critical habitat determinations and 
designations during FY 2000 as allowed by our funding allocation for 
that year. As explained in detail in the Listing Priority Guidance, our 
listing budget is currently insufficient to allow us to immediately 
complete all of the listing actions required by the Act. Deferral of 
the critical habitat designation for the riparian brush rabbit and 
riparian woodrat will allow us to concentrate our limited resources on 
higher priority critical habitat and other listing actions, while 
allowing us to put in place protections needed for the conservation of 
the riparian brush rabbit and riparian woodrat without further delay. 
However, because we have successfully

[[Page 8888]]

reduced, although not eliminated, the backlog of other listing actions, 
we anticipate in FY 2000 and beyond giving higher priority to critical 
habitat designation, including designations deferred pursuant to the 
Listing Priority Guidance, such as the designation for these species, 
than we have in recent fiscal years.
    We plan to employ a priority system for deciding which outstanding 
critical habitat designations should be addressed first. We will focus 
our efforts on those designations that will provide the most 
conservation benefit, taking into consideration the efficacy of 
critical habitat designation in addressing the threats to the species, 
and the magnitude and immediacy of those threats. We will develop a 
proposal to designate critical habitat for the riparian brush rabbit 
and riparian woodrat as soon as feasible, considering our workload 
priorities. Unfortunately, for the immediate future, most of Region 1's 
listing budget must be directed to complying with numerous court orders 
and settlement agreements, as well as due and overdue final listing 
determinations (like the one at issue in this case).

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
activities. Recognition through listing encourages and results in 
conservation actions by Federal, State, local agencies, private 
organizations, and individuals. The Act provides for possible land 
acquisition and cooperation with the State and requires that recovery 
actions be carried out for all listed species. The protection required 
of Federal agencies and the prohibitions against certain activities 
involving listed species 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 with us on any action that is likely to jeopardize the continued 
existence of a species proposed for listing or result in destruction or 
adverse modification of proposed critical habitat. If a species is 
listed subsequently, section 7(a)(2) requires Federal agencies to 
ensure that activities they authorize, fund, or carry out are not 
likely to jeopardize the continued existence of the 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 us. As part of 
our outreach efforts, we will notify the Corps and U.S. Bureau of 
Reclamation (BOR), as well as affected landowners, to ensure they are 
aware of the species' presence and clarify their obligations in 
protecting both species under the Act.
    Federal actions that may require conference or consultation with us 
include activities by the Corps that fund or authorize levee and 
channel maintenance projects along the lower San Joaquin River and its 
tributaries, the operation of upstream water storage facilities and 
dams by the Corps and BOR, and oversight of flowage (flood) and 
restoration easements by the Corps over riparian lands downstream from 
these dams. Additionally, the Federal Emergency Management Agency may 
be required to consult if an emergency action affected either of these 
    Listing the riparian brush rabbit and riparian woodrat as 
endangered triggers the development of a recovery plan. Such a plan 
establishes a conservation framework for State, Federal, and local 
governmental planning. The plan sets recovery priorities and estimates 
costs of various tasks necessary to accomplish them. The plan also 
would describe site-specific management actions necessary to achieve 
conservation and survival of these subspecies. The riparian brush 
rabbit and the riparian woodrat are both included in the final 
``Recovery Plan for Upland Species of the San Joaquin Valley, 
California'' (Service 1998), and thus the recovery planning process is 
already under way.
    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 17.21, in part, make it illegal for 
any person subject to the jurisdiction of the United States to take 
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap, 
capture, or collect; or to attempt any of these), 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. It also is illegal to possess, sell, deliver, carry, 
transport, or ship any such wildlife that has been taken illegally. 
Certain exceptions apply to our agents and State conservation agencies.
    We may be able to issue permits to carry out otherwise prohibited 
activities involving endangered wildlife 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. Under some circumstances, 
we can issue permits for a specified period for species in trade in 
order to relieve undue economic hardship that would be suffered if such 
relief were not available.
    Our policy, as published in the Federal Register on July 1, 1994 
(59 FR 34272), is to identify to the maximum extent practicable at the 
time a species is listed those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of listing on 
proposed and ongoing activities within the species' range and to assist 
the public in identifying measures needed to protect the species. We 
believe that, based on the best available information, the following 
actions would not likely result in a violation of section 9:
    (1) Possession of legally acquired riparian brush rabbits and 
riparian woodrats;
    (2) Light to moderate livestock grazing that prevents or minimizes 
the encroachment of invasive plant species;
    (3) Federally approved projects that involve activities such as 
discharge of fill material, draining, ditching, tiling, pond 
construction, stream channelization or diversion, or alteration of 
surface or ground water into or out of riparian areas (i.e., due to 
roads, impoundments, discharge pipes, storm water detention basins, 
etc.), or wildlife habitat restoration, when such activity is conducted 
in accordance with any reasonable and prudent measures given by us in 
accordance with section 7 of the Act;
    (4) Ongoing activities at the Park that are compatible with 
sustaining a viable population of both subspecies. These activities 
include camping and recreational activities such as picnicking, 
swimming, hiking, and fishing, as well as routine operations such as 
wildfire management, mowing, trail clearing, repairing water and sewer 
lines, removing hazardous trees, and the application of insecticides 
and herbicides rodenticides consistent with label instructions and 
    Activities that we believe could potentially harm the riparian 
brush rabbit and the riparian woodrat and

[[Page 8889]]

result in a violation of section 9 include, but are not limited to, the 
    (1) Unauthorized collecting, handling, or holding in captivity of 
either of these subspecies;
    (2) Unauthorized destruction/alteration of the subspecies habitat 
through the discharge of fill material, draining, ditching, tiling, 
pond construction, stream channelization or diversion, or the 
alteration of surface or ground water flow into or out of a riparian 
area (i.e., due to roads, impoundments, discharge pipes, storm water 
detention basins, etc.);
    (3) Violation of discharge permits;
    (4) Burning, cutting, or mowing of riparian vegetation, repairing 
water and sewer lines, and the spraying of insecticides or herbicides, 
if conducted in an untimely or inappropriate manner (e.g., when 
individuals of these subspecies would be killed or injured, when 
reproductive efforts would be disrupted);
    (5) Rodenticide applications if conducted in an untimely or 
inappropriate manner, or in violation of label restrictions;
    (6) Discharges or dumping of toxic chemicals, silt, or other 
pollutants (i.e., sewage, oil, and gasoline) onto land supporting these 
subspecies; and
    (7) Interstate and foreign commerce (commerce across State lines 
and international boundaries) and import/export (as discussed earlier 
in this section) without prior obtainment of an endangered species 
permit. Permits to conduct these activities are available for purposes 
of scientific research and enhancement of propagation or survival of 
the species.
    Questions regarding whether specific activities may constitute a 
violation of section 9 should be directed to the Field Supervisor of 
our Sacramento Field Office (see ADDRESSES section). Requests for 
copies of the regulations concerning listed wildlife and general 
inquiries regarding prohibitions and permits may be addressed to the 
U.S. Fish and Wildlife Service, Ecological Services, Endangered Species 
Permits, 911 N.E. 11th Avenue, Portland, Oregon, 97232-4181 (telephone 
503/231-2063; facsimile 503/231-6243).

National Environmental Policy Act

    We have determined that we do not need to prepare Environmental 
Assessments and Environmental Impact Statements, as defined under the 
authority of the National Environmental Policy Act of 1969, in 
connection with regulations adopted pursuant to section 4(a) of the 
Endangered Species Act of 1973, as amended. We published a notice 
outlining our reasons for this determination in the Federal Register on 
October 25, 1983 (48 FR 49244).

Required Determinations

    This rule does not contain any information collection requirements 
for which the Office of Management and Budget (OMB) approval under the 
Paperwork Reduction Act, 44 U.S.C. 3501 et seq. is required. An 
information collection related to the rule pertaining to permits for 
endangered and threatened species has OMB approval and is assigned 
clearance number 1018-0094. This rule does not alter that information 
collection requirement. For additional information concerning permits 
and associated requirements for endangered species, see 50 CFR 17.22.

References Cited

    A complete list of all references we cited, as well as others, is 
available upon request from the Field Supervisor, U.S. Fish and 
Wildlife Service, Sacramento Fish and Wildlife Office (see ADDRESSES 
    Author. The primary authors of this final rule are Heather Bell and 
Diane Windham, U.S. Fish and Wildlife Service, Sacramento Fish and 
Wildlife Office (see ADDRESSES section), telephone 916/414-6600.

List of Subjects in 50 CFR Part 17

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

Final Regulation Promulgation

    We amend part 17, subchapter B of chapter I, title 50 of the Code 
of Federal Regulations, as set forth below:


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

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

    2. Amend section 17.11(h) by adding the following, in alphabetical 
order under MAMMALS, to the List of Endangered and Threatened Wildlife:

Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened

                   *                  *                  *                  *                  *                  *                  *

                   *                  *                  *                  *                  *                  *                  *
Rabbit, riparian brush...........  Sylvilagus bachmani   U.S.A. (CA)........  Entire.............  E                       687           NA           NA

                   *                  *                  *                  *                  *                  *                  *
Woodrat, riparian (San Joaquin     Neotoma fuscipes      U.S.A. (CA)........  Entire.............  E                       687           NA           NA
 Valley).                           riparia.

                   *                  *                  *                  *                  *                  *                  *

[[Page 8890]]

    Dated: January 31, 2000.
Jamie Rappaport Clark,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 00-4207 Filed 2-22-00; 8:45 am]