62276 Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018–AE40

Endangered and Threatened Wildlife

and Plants; Proposed Endangered

Status for the Riparian Brush Rabbit

and Riparian Woodrat

AGENCY: Fish and Wildlife Service,

Interior.

ACTION: Proposed rule.

SUMMARY: The Fish and Wildlife Service

(Service) proposes to list the riparian

brush rabbit (Sylvilagus bachmani

riparius) and the riparian (San Joaquin

Valley) woodrat (Neotoma fuscipes

riparia) as endangered species pursuant

to the Endangered Species Act of 1973,

as amended (Act). The brush rabbit and

woodrat inhabit riparian communities

along the lower portions of the San

Joaquin and Stanislaus rivers in the

northern San Joaquin Valley, California.

Only a single remaining population of

each species has been confirmed.

Potential threats to these species

include flooding, wildfire, predation,

and other random factors. This

proposal, if made final, would extend

the Act’s protective provisions to these

animals.

DATES: Comments from all interested

parties must be received by January 20,

1998. Public hearing requests must be

received by January 5, 1998.

ADDRESSES: Comments and materials

concerning this proposal should be sent

to the U.S. Fish and Wildlife Service,

3310 El Camino Ave., Suite 130,

Sacramento, California 95821.

Comments and materials received will

be available for public inspection, by

appointment, during normal business

hours at the above address.

FOR FURTHER INFORMATION CONTACT:

Diane Windham at the above address

(telephone 916/979–2725).

SUPPLEMENTARY INFORMATION:

Background

The riparian brush rabbit (Sylvilagus

bachmani riparius) was described as a

distinct subspecies by Orr (1935) and is

one of 13 subspecies of S. bachmani

(Hall 1981). Sylvilagus bachmani

belongs to the order Lagomorpha and

family Leporidae. The riparian brush

rabbit is a medium to small cottontail

with a total length of 300 to 375

millimeters (mm) (11.8 to 14.8 inches

(in)) and a mass of 500 to 800 grams (g)

(1.1 to 1.8 pounds). It 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 bachmani (Orr 1940). The color

varies from dark brown to gray above to

white underneath. The subspecies

visually resembles the desert cottontail

(Sylvilagus audubonii), a species that

also occurs in riparian habitats within

the historic range of the riparian brush

rabbit. In-hand identification is required

to definitively distinguish between

young individuals of these species

(Williams 1993).

Brush rabbits in general breed

between December and May or June

(Mossman 1955). 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, Orr 1942). The young

are born naked, blind, and helpless and

open their eyes in 10 days (Orr 1940,

Orr 1942). Young rabbits remain in the

nest about 2 weeks before venturing out,

and the female will continue to suckle

her young for 2 to 3 weeks after their

birth. Orr (1940) reported a mean litter

size of between three and four with a

range of two to five, while Mossman

(1955) reported an average of four with

a range of three to six. Riparian brush

rabbits grow to adult size in 4 to 5

months, but do not reach sexual

maturity until the winter following

birth. Females give birth to about 5

litters per season with an estimated

average of 9 to 16 young per breeding

season (Basey 1990). The percentage of

females active during the breeding

season is unknown, but in 1 study, 9 of

25, or 36 percent of, female adults

examined showed no signs of

reproductive activity (Basey 1990).

The habitat of the riparian brush

rabbit is riparian forests with a dense

shrub layer. Common food plants in

riparian brush rabbit habitat include

Rosa californica (California wild rose),

Rubus ursinus (Pacific blackberry), Vitis

californica (wild grape), Sambucus

mexicana (elderberry), and grasses

(Williams 1988, 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 male home ranges do not

overlap the primary activity centers

within female territories (Basey 1990).

The riparian brush rabbit is currently

restricted to a single population at

Caswell Memorial State Park, San

Joaquin County, along the Stanislaus

River (Williams and Basey 1986). In

surveys conducted in all potential

habitat along the Merced, San Joaquin,

Stanislaus, and Tuolumne rivers during

1985 and 1986, no additional

populations of riparian brush rabbits

were located (Williams 1988). A

maximum of about 81 hectares (ha) (198

acres (ac)) in Caswell Memorial State

Park are suitable habitat for riparian

brush rabbit (Williams 1993). During

periods of heavy flooding, when

virtually no suitable habitat remains

exposed as a refugium, the population

can drop dramatically. Williams (1988)

estimated a population low of 10 or

fewer individuals after severe winter

flooding in 1985–86. Extended flooding

occurred during the winter and spring

of 1997, but no population estimate is

yet available (see factor A in the

‘‘Summary of Factors Affecting the

Species’’ section). Such low population

levels may make this subspecies

extremely vulnerable to detrimental

genetic processes and random events

(see factor E in the ‘‘Summary of Factors

Affecting the Species’’ section).

Maximum population estimates from

surveys conducted in recent years at

Caswell Memorial State Park are 88 to

452 individuals (Williams 1988), 320 to

540 individuals (Basey 1990), and 170

to 608 individuals (Williams 1993).

Because this subspecies was not

described until after it is believed to

have been extirpated from most of its

historic range, definitive information on

its former distribution is lacking. Even

though riparian brush rabbit specimen

records and sightings were known only

from along the San Joaquin River near

the boundary of San Joaquin and

Stanislaus counties, Orr (1940) believed,

based on the presence of suitable

habitat, that its historic range extended

along the San Joaquin river system, from

Stanislaus County north to the

Sacramento-San Joaquin River Delta. It

apparently has been extirpated from the

Delta, as well as most of the lower San

Joaquin River and its tributaries—the

Stanislaus, Tuolumne, and Merced

rivers (Williams 1986). The range of the

subspecies likely extended farther

upstream south of the Merced River,

assuming that suitable habitat occurred

historically along the length of the San

Joaquin River system (Williams and

Basey 1986).

The riparian (San Joaquin Valley)

woodrat (Neotoma fuscipes riparia) was

first described by Hooper (1938) and is

1 of 11 subspecies of N. fuscipes in the

family Muridae (order Rodentia). The

subspecies has been retained by Hall

(1981) and Williams (1986 and 1993).

The riparian woodrat is a medium-sized

rodent, its total length averaging 443

mm (17.4 in), its tail length averaging

217 mm (8.5 in) (Hooper 1938), and its

total weight, based on measurements of

other subspecies, averaging about 227 g
Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules 62277

(8 ounces), with marked seasonal

variation (Williams et al. 1992). The

riparian woodrat is predominantly gray

and cinnamon above and whitish

beneath, with white hindfeet. Neotoma

fuscipes riparia is distinguished from

other subspecies of N. fuscipes by size

and coloration of the body, tail, ears, or

feet, in addition to skull measurements

and characteristics (Hooper 1938).

The following information is taken

from a number of studies on Neotoma

fuscipes, including riparia and related

subspecies. Mostly active at night, the

woodrat’s diet is diverse and mainly

herbivorous, with leaves, fruits,

terminal shoots of twigs, flowers, nuts,

and fungi comprising the bulk of

ingested material (Williams et al. 1992).

Females have one to five litters per year

with three to four young each time.

Reproduction occurs in all months, with

the fewest pregnancies in December and

the most in February. The number 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 lodges, which are located on

the ground and 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

lodges are positioned over or against

logs (Cook 1992, cited in Williams

1993). Unoccupied houses can persist

for 20 to 30 years (Williams 1993).

Unlike other subspecies, the riparian

woodrat occasionally builds nests in

cavities in trees and artificial wood

duck nest boxes (Williams 1986). Nest

houses usually are occupied by single

adults. Young seldom disperse far from

their natal houses, and nest clusters

occupied by related individuals tend to

develop in favored habitats. Unlike

males, females remain in or near natal

areas throughout their life (Williams et

al. 1992). At Caswell Memorial State

Park, Williams (1993) reported a mean

density of houses of 8.3 per ha (3.4 per

ac), or 757 houses on 91 ha (225 ac) of

suitable habitat; occupancy of these

houses was not verified.

In a study of another subspecies of

Neotoma fuscipes, Linsdale and Tevis

(1951, cited in Williams et al. 1992)

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 perturbations

such as fire, flood, drought, habitat

modification, and browsing and

trampling by ungulates.

Historical localities for the riparian

woodrat are distributed along the San

Joaquin, Stanislaus, and Tuolumne

rivers, and in Corral Hollow in San

Joaquin, Stanislaus, and Merced

counties (Hooper 1938, Williams 1986).

This range is similar to the presumed

historical range for the riparian brush

rabbit. Thus, prior to the statewide

reduction of riparian communities by

nearly 90 percent (Katibah 1984), the

riparian brush rabbit and woodrat

probably occurred throughout the

extensive riparian forests along major

streams flowing onto the floor of the

northern San Joaquin Valley.

The only known population of the

riparian woodrat occurs in, and

immediately adjacent to, Caswell

Memorial State Park, also the site of the

only riparian brush rabbit population

(Williams 1993). A woodrat population

was reported during the early 1970s

near the type locality at Vernalis, but

the current status of the population is

unknown (D. Williams 1986, pers.

comm. 1994). The site of an old record

at Corral Hollow, San Joaquin County,

no longer supports suitable habitat (D.

Williams, pers. comm. 1994). Cook

(1992) estimated the Caswell Park

population at 637 woodrats over 102 ha

(250 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.

Today, riparian forests of the lower

San Joaquin River and its tributaries

outside of Caswell Memorial State Park

have nearly been eliminated. The

remaining habitat is small, narrow forest

patches confined within levees. These

areas flood completely during major

storm events. Because these forest

remnants are small, isolated, and subject

to periodic prolonged flooding

(Williams and Basey 1986), their

capability to support viable populations

of these subspecies over the long-term is

doubtful. Historic habitat and refugia

from flooding in adjacent lands are now

mainly cultivated fields, orchards, and

vineyards, habitats unsuitable for these

subspecies (Williams and Basey 1986).

Flooding, wildfire, predation, and other

factors imperil their continued

existence.

Previous Federal Action

Federal action on these two species

began on September 18, 1985, when the

Service 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 the

Service on February 28, 1996 (61 FR

7596), were taxa for which information

in possession of the Service indicated

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), the Service 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 comprised taxa for which the Service

currently had substantial information on

biological vulnerability and threats to

support proposals to list them as

endangered or threatened species. The

Service 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), based on a reevaluation 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.

The February 28, 1996, combined

Animal and Plant Notice of Review (61

FR 7596) included both subspecies as

candidates.

The processing of this proposed

listing rule conforms with the Service’s

listing priority guidance for fiscal year

1997 published in the Federal Register

on December 5, 1996 (61 FR 64475). The

guidance clarifies the order in which the

Service will process rulemakings

following two related events, the lifting,

on April 26, 1996, of the moratorium on

final listings imposed on April 10, 1995

(Public Law 104–6), and the restoration

of significant funding for listing through

passage of the omnibus budget

reconciliation law on April 26, 1996,

following severe funding constraints

imposed by a number of continuing

resolutions between November 1995

and April 1996. The guidance calls for

giving highest priority to handling

emergency situations (Tier 1) and

second highest priority (Tier 2) to

resolving the status of proposed listings.

A lower priority is assigned to resolving

the conservation status of candidate

species and processing administrative

findings on petitions to add species to

the lists or reclassify species from

threatened to endangered status (Tier 3).

The lowest priority actions are in Tier

4, a category which includes processing

critical habitat determinations,

delistings, or other types of
62278 Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules

reclassifications. Processing of this

proposed rule is a Tier 3 action.

Summary of Factors Affecting the

Species

Section 4 of the Endangered Species

Act (16 U.S.C. 1533) and regulations (50

CFR part 424) promulgated to

implement the listing provisions of the

Act set forth the procedures for adding

species to the Federal lists. A species

may be determined to be an endangered

or threatened species due to one or more

of the five factors described in section

4(a)(1). These factors and their

application to the riparian brush rabbit

(Sylvilagus bachmani riparius) and the

riparian woodrat (Neotoma fuscipes

riparia) are as follows:

A. The Present or Threatened

Destruction, Modification, or

Curtailment of its Habitat or Range

Both the riparian brush rabbit and the

riparian woodrat inhabit riparian

forests, and each has been extirpated

from all of its historical range except for

a single population at Caswell Memorial

State Park along the Stanislaus River.

Katibah (1984) estimated that only

41,300 ha (102,000 ac) remain of an

estimated 373,000 ha (921,600 ac) of

pre-settlement riparian forest in

California’s Central Valley, a reduction

of 89 percent. Moreover, nearly one-half

of the remaining forests are in a

disturbed and/or degraded condition,

and it is likely that the majority of the

rest have been and continue to be

heavily impacted by human activities.

This elimination and modification of

riparian forests along valley floor river

systems was attributed to—urban;

commercial, and agricultural

development; wood cutting; land

reclamation and flood control activities;

groundwater pumping; river

channelization; dam construction; and

water diversions (Katibah 1984).

Several land use practices and related

human activities have 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 floodplains 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 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 other flood control

projects were constructed, much of the

floodplain was livestock pasture (Basey

1990). Uneven topography on the

floodplains provided escape areas for

species because some land remained

above most flood levels and contained

patches of shrubs and trees for cover.

Sites like these probably provided

refuge from flooding for brush rabbits.

Williams and Basey (1986) stated 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 hedge rows and

other residual patches of cover that

provided travel corridors and refuge

sites for the two subspecies. The effects

of catastrophic flooding are discussed

further under factor E.

Although brush clearing adversely

affected the habitat of the riparian brush

rabbit and riparian woodrat populations

at Caswell State Park in the mid-1980s

(Williams 1986), the State Park

populations are no longer directly

threatened by brush clearing, tree

cutting, or the conversion of land to

agricultural uses. Because the State Park

harbors the only known populations of

these species, these activities outside of

the park do not pose a direct threat to

either species. Such activities continue,

however, to eliminate and fragment

patches of remnant habitat within the

historic range of these species.

B. Overutilization for Commercial,

Recreational, Scientific, or Educational

Purposes

Overutilization is not known to be a

problem for either species. However, the

very small population at the remaining

site makes the riparian brush rabbit

vulnerable to extinction from

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 Caswell

Memorial State Park (as they may,

especially during times of flooding) face

a potential threat of being hunted.

C. Disease or Predation

All rabbits, including cottontails, are

known to be susceptible to a variety of

diseases that sometimes reach epidemic

proportions. The small population size

and restricted distribution of both the

riparian brush rabbit and riparian

woodrat increase their vulnerability to

epidemic diseases, such as tularemia in

the case of the brush rabbit (Williams

1988). However, the significance of the

threat of disease to the riparian brush

rabbit and riparian woodrat is not

known.

Coyotes, gray foxes, long-tailed

weasels, raccoons, feral cats and dogs,

hawks, and owls are known predators of

brush rabbits as well as other small

mammals, including woodrats

(Williams 1988, Verner and Boss 1980,

Orr 1940). At currently depleted

population levels, predation events

could significantly affect the survival of

these two subspecies.

D. The Inadequacy of Existing

Regulatory Mechanisms

Federal, State, and local laws and

regulations have not proven adequate to

curb habitat losses for the riparian brush

rabbit and riparian woodrat. The

National Environmental Policy Act

(NEPA) and section 404 of the Clean

Water Act (CWA) represent the primary

Federal laws that potentially may afford

some protection for these species.

However, neither NEPA nor the CWA

protect candidate species. Moreover,

brush clearing, tree cutting, and the

conversion to agricultural uses that are

adversely affecting these species are

generally unregulated at any level of

government. 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.

Caswell Memorial State Park has a

management plan for the riparian brush

rabbit that provides some measure of

protection to the population. This plan

does not address the riparian woodrat.

Despite the existence of a management

plan, both the riparian brush rabbit and

woodrat remain vulnerable to threats

and hazards originating outside of the

park (see factor E below).

The California Environmental Quality

Act (CEQA) requires a full public

disclosure of the potential

environmental impact of proposed

projects. 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 other agencies

concerned with resources affected by

the project. Section 15065 of the CEQA

guidelines requires a finding of

significance if a project has the potential

to ‘‘reduce the number or restrict the
Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules 62279

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. Once significant impacts are

identified, the lead agency has the

option to require mitigation for effects

through changes in the project or to

decide that overriding considerations

make mitigation infeasible. In the latter

case, projects may be approved that

cause significant environmental

damage, such as destruction of

endangered species. Protection of listed

species through CEQA is, therefore, at

the discretion of the lead agency

involved. The CEQA provides that when

overriding social and economic

considerations can be demonstrated,

project proposals may go forward, even

in cases where the continued existence

of the species may be jeopardized, or

where adverse impacts are not mitigated

to the point of insignificance.

Furthermore, proposed revisions to

CEQA guidelines, if made final, may

weaken protections for threatened,

endangered, and other sensitive species.

The California Endangered Species

Act affords the riparian brush rabbit

some conservation benefits. The animal

was listed as an endangered species by

the State of California in May 1994.

Although this State law provides a

measure of protection to the species,

resulting in the formulation of

mitigation measures to reduce or offset

impacts for any projects proposed in

riparian brush rabbit habitat, this law is

not adequate to prevent the ongoing loss

of riparian habitat. Many of the threats

facing the riparian brush rabbit and the

riparian woodrat (see factor E below) are

not amenable to management without

supplementing the depleted habitat base

upon which these species depend.

Moreover, State listing does not provide

a nexus with Federal agencies, such as

the Corps, that regulate flood control

and other activities in waters of the

United States.

E. Other Natural or Manmade Factors

Affecting its Continued Existence

Random events such as flooding or

fire may be more critical than genetic

considerations to the survival of species

(Shaffer 1987, Gilpin 1987). This is

especially true for taxa, like the riparian

brush rabbit and woodrat, that are

represented by only one or a few small,

isolated populations. In such cases,

little or no possibility of recolonization

exists if a chance environmental or

human-caused catastrophe affects the

population. Riparian habitat at Caswell

State Park is confined entirely within

river levees, and offers less habitat value

for these subspecies during periods of

high stream flow. This habitat is

routinely flooded during the wet winter

season. Major flooding likely drowns a

significant portion of the populations,

eliminates foraging habitat and shelter

for prolonged periods, and exposes

brush rabbits and woodrats to increased

predation by concentrating the

population on high ground and in areas

with little or no cover. Only about 3.6

ha (8.9 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). Basey (1990) concluded, based on

visual sightings and pellet surveys, that

this same riparian brush rabbit

population may have been reduced to

fewer than 15 to 20 individuals during

flooding in 1983.

The floods of January 1997 left about

85 percent of Caswell Memorial State

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. During efforts in January to

locate and potentially rescue stranded

riparian brush rabbits, only a single

rabbit pellet was found (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 found two rabbit fecal pellets,

but no other sign of rabbits or woodrat

activity. Trapping surveys were initiated

in early May, well after flood waters had

receded, in hopes that any surviving

rabbits would be located. During 22

nights of trapping, no rabbits were

caught, one rabbit was sighted, and at

another location, fresh rabbit tracks

were found (D. Williams, in litt. 1997).

In comparison, during trapping efforts

of similar intensity in January 1993, 41

brush rabbits were captured and several

rabbits were sighted (D. Williams, in litt.

1997). A significant increase in brush

rabbit sign was noted during surveys

after May 30, 1997, including the

finding of four separate groups of fecal

pellets, two separate groups of dust

baths with rabbit tracks, about a dozen

rabbit runways, and one rabbit sighted

by spotlight (P. Kelly, San Joaquin

Valley Endangered Species Recovery

Program, in litt. 1997a, 1997b). Two

sightings were also reported by park

visitors (K. Graham, California Dept. of

Parks and Recreation in Kelley, in litt.

1997a).

The riparian woodrat also is

vulnerable to flooding, 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 nests occur on the ground

(Williams 1993, pers. comm. 1994).

After the January 1997 floods left

Caswell Memorial State Park under 0.6–

3.0 m (2–10 ft) of water for 2 to 7 weeks,

trapping and survey efforts in May 1997

resulted in 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

Caswell Memorial State 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 species

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 (1,116 ft). Desert

cottontails, in contrast, may return

home when displaced as much as 4.8

kilometers (3 miles). Therefore, if

displaced by flooding more than about

340 m (1,116 ft) from their home areas,

riparian brush rabbits may be stranded

in habitats where desert cottontails have

a competitive advantage.

The number of individuals in the sole

population of each subspecies is now

sufficiently low that the effects of

inbreeding may result in the expression

of deleterious genes in the population

(Gilpin 1987). Deleterious genes reduce

individual fitness in various ways, the

most typical being decreased

survivorship of young. Small

populations are also more at risk due to

the effects of genetic drift, a decrease in

genetic variation 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 adapt to

environmental changes.

Although Caswell Memorial State

Park provides protection to the riparian

brush rabbit and the riparian woodrat

against some threats, the park is also a

recreational facility and consequently

faces an increased threat of humancaused wildfires that may kill both the

riparian brush rabbit and woodrat and

destroy their habitat (Basey 1990). The
62280 Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules

brushy areas most vulnerable to fire are

important habitat for brush rabbits and

woodrats (Basey 1990). Between 1975

and 1987, 10 wildfires were reported

within the park. After a large area

burned in 1981, no evidence of brush

rabbits was found in the area (Basey

1990). The extent to which recreational

activities, such as vehicular and

pedestrian traffic, dogs, etc., also may

affect habitat quality is unknown.

The Service has carefully assessed the

best scientific and commercial

information available regarding the past,

present, and future threats faced by

these subspecies in determining to

propose this rule. Based on this

evaluation, the preferred action is to list

the riparian brush rabbit (Sylvilagus

bachmani riparius) and the riparian

woodrat (Neotoma fuscipes riparia) as

endangered. The single, small

population of each of these two taxa

render them vulnerable to a wide array

of threats. Increases in human

population and pressures associated

with urban development, as well as the

inadequacy of existing regulatory

mechanisms have led to a significant

loss of historic habitat and reduced

these subspecies to the brink of

extinction. Both subspecies currently

face threats from floods, wildfires, and

predation. Riparian forests, the habitat

type upon which the riparian brush

rabbit and woodrat depend, are so

depleted along the San Joaquin River

system that all habitat remnants outside

of Caswell Memorial State Park are too

small and isolated to support viable

populations of these animals. Thus,

even if the few remaining unsurveyed

tracts of habitat do harbor these

subspecies, the status of the riparian

brush rabbit and woodrat would not

change and listing of these taxa as

endangered would be warranted.

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, and implementing regulations

(50 CFR 424.12) require that, to the

maximum extent prudent and

determinable, the Secretary designate

critical habitat at the time the species is

determined to be endangered or

threatened. Service regulations (50 CFR

424.12(a)) state that critical habitat is

not determinable if information

sufficient to perform required analyses

of the impacts of the designation is

lacking or if the biological needs of the

species are not sufficiently known to

permit identification of an area as

critical habitat. Section 4(b)(2) of the

Act requires the Service to consider

economic and other relevant impacts of

designating a particular area as critical

habitat on the basis of the best scientific

data available. The Secretary may

exclude any area from critical habitat if

he determines that the detriments of

such exclusion outweigh the

conservation benefits, unless to do such

would result in the extinction of the

species. Service regulations (50 CFR

424.12(a)(1)) state that designation of

critical habitat is not prudent when one

or both of the following situations

exist—(1) The species is threatened by

taking or other human activity, and

identification of critical habitat can be

expected to increase the degree of threat

to the species, or (2) such designation of

critical habitat would not be beneficial

to the species.

The Service finds that the designation

of critical habitat for the riparian brush

rabbit and riparian woodrat is not

prudent because such designation

would not provide any additional

benefit to the two species beyond that

conferred by listing them as endangered

species. The basis for these conclusions,

including the factors considered in

weighing the benefits against the

detriments of designation, is explained

below.

As discussed above, the sole site

currently occupied by the riparian brush

rabbit and the riparian woodrat is

within Caswell Memorial State Park,

and no other currently suitable habitat

for these species is known to exist

within their historical ranges (Basey

1990). State Park designation provides

protection to the natural resources of the

park, such as through hunting

prohibitions, and facilitates appropriate

resource management. This protection

would not be increased through critical

habitat designation.

A high potential for Federal

involvement exists because of the flood

control activities of the Corps and water

regulation activities of the U.S. Bureau

of Reclamation (BOR). Section 7 of the

Act requires that Federal agencies

refrain jeopardizing the continued

existence of a listed species and from

contributing to the destruction or

adverse modification of critical habitat.

However, implementing regulations (50

CFR part 402) define ‘‘jeopardize the

continued existence of’’ and

‘‘destruction or adverse modification of’’

in virtually identical terms. Jeopardize

the continued existence of means to

engage in an action ‘‘that reasonably

would be expected . . . to reduce

appreciably the likelihood of both the

survival and recovery of a listed

species.’’ Destruction or adverse

modification means an ‘‘alteration that

appreciably diminishes the value of

critical habitat for both the survival and

recovery of a listed species.’’ Common

to both definitions is an appreciable

detrimental effect on both survival and

recovery of a listed species, in the case

of critical habitat by reducing the value

of the habitat so designated. In this case,

because each species exists as a single,

small population, it is even clearer that

any activity that would destroy or

adversely modify their habitat would

also likely jeopardize their continued

existence. For this reason, designation

of critical habitat provides no benefit

beyond that conferred by listing.

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 results in

public awareness and 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 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 that implement

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 the

Service 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, section 7(a)(2) requires Federal
Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules 62281

agencies to insure 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 the

Service.

Federal actions that may require

conference or consultation with the

Service include the funding or

authorization by the Corps of levee and

channel maintenance projects along the

lower San Joaquin River and its

tributaries and the operation of

upstream dams by the Corps and the

BOR.

Listing the riparian brush rabbit and

riparian woodrat as endangered species

would also provide for the development

of a recovery plan (or plans) for the taxa.

Such a plan would establish a

framework for State, Federal, and local

governmental efforts to coordinate

conservation planning for these animals.

The plan would set recovery priorities

and estimate 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 Act and implementing

regulations set forth a series of general

prohibitions and exceptions that apply

to all endangered wildlife. These

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, 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 such 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 agents of the Service and State

conservation agencies.

Permits may be issued 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,

permits may be issued 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.

It is the policy of the Service,

published in the Federal Register on

July 1, 1994 (59 FR 34272), to identify

to the maximum extent 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 this listing on proposed and ongoing

activities within the range of the two

species. The Service believes that, based

on the best available information, the

following actions will not result in a

violation of section 9:

(1) Possession of legally acquired

riparian brush rabbits and riparian

woodrats;

(2) Light to moderate livestock grazing

in riparian brush rabbit and riparian

woodrat habitat that prevents or

minimizes the encroachment of invasive

plant species and does not significantly

reduce shrub cover;

(3) Federally approved projects, such

as those involving the 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, stormwater detention

basins, etc.), when conducted in

accordance with any reasonable and

prudent measures given by the Service

in accordance with section 7 of the Act.

Activities that the Service believes

could potentially harm the riparian

brush rabbit and the riparian woodrat

and result in ‘‘take’’ include, but are not

limited to:

(1) Unauthorized collecting or

handling of the species;

(2) Unauthorized destruction/

alteration of occupied habitat of the

riparian brush rabbit or riparian

woodrat 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 riparian

habitat of these two species (i.e., due to

the construction/installation of roads,

impoundments, discharge pipes,

stormwater detention basins, etc.);

(3) Any activity constituting a

violation of discharge permits which

results in death of or injury to riparian

brush rabbits or riparian woodrats or

which results in degradation of their

occupied habitat;

(4) Burning, cutting, or mowing of

riparian vegetation which results in

death of or injury to riparian brush

rabbits or riparian woodrats or which

results in degradation of their occupied

habitat;

(5) Application of pesticides in

violation of label restrictions which

results in death of or injury to riparian

brush rabbits or riparian woodrats;

(6) Discharging or dumping toxic

chemicals, silt, or other pollutants (i.e.,

sewage, oil, or gasoline) which results in

death of or injury to riparian brush

rabbits or riparian woodrats;

(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 will constitute a violation of

section 9 should be directed to the Field

Supervisor of the Service’s 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).

Public Comments Solicited

The Service intends that any final

action resulting from this proposal will

be as accurate and as effective as

possible. Therefore, comments or

suggestions from the public, other

concerned governmental agencies, the

scientific community, industry, or any

other interested party concerning this

proposed rule are hereby solicited. The

Service will also comply with its policy

on peer review, published on July 1,

1994 (59 FR 34270), in the processing of

this proposed rule. Comments

particularly are sought concerning:

(1) Biological, commercial trade, or

other relevant data concerning any

threat (or lack thereof) to these species;

(2) The location of any additional

populations of these species and the

reasons why any habitat should or

should not be determined to be critical

habitat as provided by section 4 of the

Act;

(3) Additional information concerning

the range, distribution, and population

size of these species;

(4) Current or planned activities in the

subject area and their possible impacts

on these species; and,

(5) Information on biological

considerations, land ownership, habitat

restoration potential, flood control

constraints, and other factors that may

lead to a critical habitat determination.
62282 Federal Register / Vol. 62, No. 225 / Friday, November 21, 1997 / Proposed Rules

Final promulgation of the regulations

for these species will take into

consideration the comments and any

additional information received by the

Service, and such communications may

lead to a final regulation that differs

from this proposal.

The Act provides for one or more

public hearings on this proposal, if

requested. Requests must be received

within 45 days of the date of publication

of the proposal in the Federal Register.

Such requests must be made in writing

and be addressed to the Field

Supervisor, Sacramento Field Office

(see ADDRESSES section).

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).

Required Determinations

The Service has examined this

regulation under the Paperwork

Reduction Act of 1995 and found it to

contain no information collection

requirements.

References Cited

A complete list of all references cited

herein, as well as others, is available

from the Field Supervisor, Sacramento

Field Office (see ADDRESSES section).

Authors. The primary authors of this

proposed rule are Peter Sorensen and

Diane Windham, U.S. Fish and Wildlife

Service, Sacramento Field Office (see

ADDRESSES section), telephone 916/979–

2725.

List of Subjects in 50 CFR Part 17

Endangered and threatened species,

Exports, Imports, Reporting and

recordkeeping requirements,

Transportation.

Proposed Regulation Promulgation

Accordingly, the Service hereby

proposes to amend part 17, subchapter

B of chapter I, title 50 of the Code of

Federal Regulations, as set forth below:

PART 17—[AMENDED]

1. The authority citation for Part 17

continues to read as follows:

Authority: 16 U.S.C. 1361–1407; 16 U.S.C.

1531–1544; 16 U.S.C. 4201–4245; Pub. L. 99–

625, 100 Stat. 3500, unless otherwise noted.

2. Section 17.11(h) is amended by

adding the following, in alphabetical

order under MAMMALS, to the List of

Endangered and Threatened Wildlife:

§ 17.11 Endangered and threatened

wildlife.

* * * * *

(h) * * *

Species

Historic range

Vertebrate population where endangered or threatened

Status When listed Critical

habitat

Special

rules Common name Scientific name

MAMMALS

* * * * * * *

Rabbit, riparian

brush.

Sylvilagus bachmani

riparius.

U.S.A. (CA) ............. Entire ....................... E .................... NA NA

* * * * * * *

Woodrat, riparian

(San Joaquin Valley).

Neotoma fuscipes

riparia.

U.S.A. (CA) ............. Entire ....................... E .................... NA NA

* * * * * * *

Dated: October 30, 1997.

Jamie Rappaport Clark,

Director, U.S. Fish and Wildlife Service.

[FR Doc. 97–30553 Filed 11–20–97; 8:45 am]

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