[Federal Register Volume 59, Number 22 (Wednesday, February 2, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2303]


[[Page Unknown]]

[Federal Register: February 2, 1994]


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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AC34

 

Endangered and Threatened Wildlife and Plants; Proposed 
Endangered Status for the California Red-legged Frog

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) proposes to 
determine the California red-legged frog (Rana aurora draytonii) as 
endangered pursuant to the Endangered Species Act of 1973, as amended 
(Act). The California red-legged frog is found primarily in wetlands 
and streams in coastal drainages of central California. It has been 
extirpated from 75 percent of its former range. This subspecies is 
threatened throughout its remaining range by a wide variety of human 
impacts, including urban encroachment, construction of reservoirs and 
water diversions, introduction of exotic predators and competitors, and 
stochastic events. This proposed rule, if made final, would extend the 
Act's protection to the California red-legged frog. The Service seeks 
data and comments from the public on this proposed rule.

DATES: Comments from all interested parties must be received by April 
4, 1994. Public hearing requests must be received by March 21, 1994.

ADDRESSES: Written comments and materials concerning this proposed rule 
should be submitted to the Field Supervisor, Sacramento Field Office, 
U.S. Fish and Wildlife Service, 2800 Cottage Way, room E-1803, 
Sacramento, California 95825-1846. Comments and materials received will 
be available for public inspection, by appointment, during normal 
business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Mr. Wayne S. White, State Supervisor, 
at the above address or telephone 916/978-4613.

SUPPLEMENTARY INFORMATION:

Background

    The California red-legged frog (Rana aurora draytonii) is one of 
two subspecies of the red-legged frog (Rana aurora) found on the 
Pacific coast. R. a. draytonii was first described by Baird and Girard 
in 1852 from specimens collected at or near the city of San Francisco 
(Storer 1925). The historical range of the California red-legged frog 
extended from the vicinity of Point Reyes National Seashore, Marin 
County, California, coastally and from the vicinity of Redding, Shasta 
County, California, inland southward to northwestern Baja California, 
Mexico (Jennings and Hayes 1985, Hayes and Krempels 1986). The northern 
red- legged frog (Rana aurora aurora) ranges from Vancouver Island, 
British Columbia, Canada, south along the Pacific coast west of the 
Cascade ranges to northern California (Del Norte County). Red-legged 
frogs found in the intervening area (Humboldt to northern Marin County) 
between the two subspecies exhibit intergrade characteristics of both 
R. a. aurora and R. a. draytonii (Hayes and Krempels 1986). Systematic 
relationships between the two subspecies are not completely understood 
(Hayes and Miyamoto 1984, Green 1985a, Green 1986, Hayes and Krempels 
1986). However, significant morphological and behavioral differences 
between the two subspecies suggest that they may actually be two 
species in secondary contact (Hayes and Krempels 1986).
    Northern Marin County represents the approximate dividing line 
between Rana aurora draytonii and intergrade populations along the 
coastal range (M. Jennings, pers. comm., 1993). California red-legged 
frogs found in Nevada (Linsdale 1938, Green 1985b) were introduced. 
This rule would not extend the Act's protection to any Rana aurora in 
Humboldt, Trinity, and Mendocino Counties, California, and Sonoma 
County, California, north and west of 38 deg.30' N and 123 deg. W, as 
well as the introduced population in Nevada.
    The California red-legged frog is the largest native frog in the 
western United States (Wright and Wright 1949), ranging from 4 to 13 
centimeters (1.5 to 5.1 inches) in length (Stebbins 1985). The abdomen 
and hind legs of adults are red; the back is characterized by small 
black flecks and larger irregular dark blotches with indistinct 
outlines on a brown, gray, olive, or reddish background color. Dorsal 
spots usually have light centers (Stebbins 1985). Dorsolateral folds 
are prominent on the back. Larvae range from 14 to 80 millimeters (mm) 
(0.6 to 3.1 inches) in length, and the background color of the body is 
dark brown and yellow with darker spots (Storer 1925).
    Several morphological and behavioral characteristics differentiate 
California red-legged frogs from northern red-legged frogs. Adult 
California red-legged frogs are significantly larger than northern red-
legged frogs by 35 to 40 mm (1.4 to 1.6 inches) (Hayes and Miyamoto 
1984). Dorsal spots of northern red-legged frogs usually lack light 
centers common to California red-legged frogs (Stebbins 1985), but this 
is not a strong diagnostic character. California red-legged frogs have 
paired vocal sacs and call in air (Hayes and Krempels 1986), whereas 
northern red-legged frogs lack vocal sacs (Hayes and Krempels 1986) and 
call underwater (Licht 1969). Female California red-legged frogs 
deposit egg masses on emergent vegetation so that the egg mass floats 
on the surface of the water (Hayes and Miyamoto 1984). Northern red-
legged frogs also attach their egg masses to emergent vegetation, but 
the mass is submerged (Licht 1969). California red-legged frogs breed 
from November to March with earlier breeding records occurring in 
southern localities (Storer 1925). California red-legged frogs found in 
coastal drainages are rarely inactive (Jennings et al. 1992), whereas 
those found in interior sites may hibernate (Storer 1925).
    The California red-legged frog occupies a fairly distinct habitat, 
combining both specific aquatic and riparian components (Hayes and 
Jennings 1988, Jennings 1988b). The adults require a dense, shrubby or 
emergent riparian vegetation closely associated with deep (>0.7 meters) 
still or slow moving water (Jennings et al. 1992). The largest 
densities of California red-legged frogs currently are associated with 
deep-water pools with dense stands of overhanging willows (Salix spp.) 
and an intermixed fringe of cattails (Typha latifolia) (Jennings 
1988b). Well-vegetated terrestrial areas within the riparian corridor 
may provide important sheltering habitat during winter. California red-
legged frogs estivate in small mammal burrows and moist leaf litter up 
to 26 meters (85 feet) from water in dense riparian vegetation (Rathbun 
et al. 1993).
    Egg masses that contain about 2,000 to 5,000 moderate-sized (2.0 to 
2.8 mm (0.08 to 0.11 inches) in diameter), dark reddish brown eggs are 
typically attached to vertical emergent vegetation, such as bulrushes 
(Scirpus spp.) or cattails (Typha spp.) (Jennings et al. 1992). Eggs 
hatch in 6 to 14 days (Jennings 1988b). The most significant mortality 
factor in the pre-hatching stage is water salinity (Jennings et al. 
1992). One hundred percent mortality occurs in eggs exposed to salinity 
levels greater than 4.5 parts per thousand (Jennings and Hayes 1990). 
Larvae undergo metamorphosis 3.5 to 7 months after hatching (Storer 
1925, Wright and Wright 1949, Jennings and Hayes 1990). Of the various 
life stages, larvae probably experience the highest mortality rates, 
with less than 1 percent of eggs laid reaching metamorphosis (Jennings 
et al. 1992). Sexual maturity is reached at 3 to 4 years of age (Storer 
1925, Jennings and Hayes 1985). California red-legged frogs may live 8 
to 10 years (Jennings et al. 1992).
    The diet of California red-legged frogs is highly variable. Hayes 
and Tennant (1985) found invertebrates to be the most common food 
items. Vertebrates, such as Pacific tree frogs (Hyla regilla) and 
California mice (Peromyscus californicus), represented over half of the 
prey mass eaten by larger frogs (Hayes and Tennant 1985). Hayes and 
Tennant (1985) found juvenile frogs to be active diurnally and 
nocturnally, whereas adult frogs were largely nocturnal. Feeding 
activity probably occurs along the shoreline and on the surface of the 
water (Hayes and Tennant 1985). Larvae probably eat algae (Jennings et 
al. 1992).
    California red-legged frogs have sustained a 75 percent reduction 
in their geographic range in California as a result of several factors 
acting singly or in combination (Jennings et al. 1992). Habitat loss 
and alteration, combined with overexploitation and introduction of 
exotic predators, were significant factors in the California red-legged 
frog decline in the early to mid 1900s. California red-legged frogs 
were extirpated from the Central Valley probably in the 1960s. 
Remaining aggregations of California red-legged frogs in the Sierran 
foothills became fragmented and were later eliminated by reservoir 
construction, continued expansion of exotic predators, grazing, and 
drought. The pattern of disappearance of California red-legged frogs in 
southern California is similar to that seen in the Central Valley, 
except that urbanization and its associated roadway, large reservoir 
(exotic predators), and stream channelization projects were the primary 
factors causing population declines.
    At present, California red-legged frogs are known to occur in about 
190 streams or drainages from 15 counties in central and southern 
California. Monterey, San Luis Obispo and Santa Barbara Counties 
support the greatest amount of currently occupied habitat. The most 
secure aggregations of California red-legged frogs are found in aquatic 
sites that support substantial riparian and aquatic vegetation and lack 
exotic predators (e.g., bullfrogs, mosquitofish, largemouth and 
smallmouth bass). The majority of aggregations are threatened, however, 
by expansion of exotic predators, proposed residential development, 
water storage projects, and other factors. For example, within the 
Central Valley hydrographic basin, only six drainages, all on the Coast 
range slope of the San Joaquin Valley, are known or likely to support 
California red-legged frogs, compared to over 60 historic locality 
records for this basin. Two of these drainages, known to support 
significant numbers of California red-legged frogs, are sites of 
proposed large reservoir projects. Also, in southern California, 
California red-legged frogs are known from only 4 locations south of 
the Tehachapi Mountains, compared to over 80 historic locality records 
for this region. Only three areas currently support more than 350 
adults.

Previous Federal Action

    On January 29, 1992, the Service received a petition from Drs. Mark 
R. Jennings, Marc P. Hayes, and Dan C. Holland to list the California 
red-legged frog (Rana aurora draytonii). The petition specified 
endangered or threatened status by distinct drainages (watersheds) 
within the range of the species. On October 5, 1992, the Service 
published a 90-day petition finding (57 FR 45761) that substantial 
information had been presented indicating the requested action may be 
warranted. Public comments were requested on the status of this 
species. The California red-legged frog had been included as a Category 
1 candidate species in the Service's November 21, 1991, Animal Notice 
of Review (56 FR 58804). Category 1 candidates are species for which 
the Service has substantial information on biological vulnerability and 
threat to support proposals to list them as endangered or threatened. 
On July 19, 1993, the Service published a 12-month finding on the 
petitioned action (58 FR 38553). This finding indicated that listing of 
the California red-legged frog was warranted and that a proposed rule 
would be published promptly.

Summary of Factors Affecting the Species

    Section 4 of the Endangered Species Act (16 U.S.C. 1531 et seq.) 
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 California 
red-legged frog (Rana aurora draytonii) are as follows:
    A. The present or threatened destruction, modification, or 
curtailment of its habitat or range. Herpetologists have noted the 
decline or extirpation of California red-legged frogs from the San 
Francisco Bay area (Sean J. Barry, University of California, Davis, in 
litt., 1992; Robert C. Stebbins, University of California, Berkeley, in 
litt., 1993; John S. Applegarth, herpetologist, in litt., 1993; Ed Ely, 
herpetologist, in litt., 1993), the Salinas River drainage (Lawrence E. 
Hunt, University of California, Santa Barbara, in litt., 1993), the San 
Luis Obispo, Santa Barbara, and Ventura County area (Aryan I. Roest, 
California Polytechnic State University, San Luis Obispo, in litt., 
1993; Samuel S. Sweet, University of California, Santa Barbara, in 
litt., 1993), southern California (Patrick McMonagle, herpetologist, in 
litt., 1993; John D. Goodman, zoologist, in litt., 1992; Robert B. 
Sanders, San Bernardino County Museum, in litt., 1992; John Stephenson, 
U.S. Forest Service, in litt., 1993; Michael C. Long, Eaton Canyon Park 
Nature Center, in litt., 1992; Joseph F. Copp, herpetologist, in litt., 
1993; Glenn R. Stewart, California Polytechnic University, Pomona, in 
litt., 1993; Walter B. Allen, herpetologist, in litt., 1993; Robert 
Fisher, University of California, Davis, in litt., 1993), central 
California (Martin R. Brittan, California State University, Sacramento, 
in litt., 1993), and the northern and southern Sierra Nevada foothills 
(Jay Wright, Feather River College, Quincy, in litt., 1993; Alan M. 
McCready, California State University, Sacramento, in litt., 1992).
    These observations and data provided by the petitioners indicate 
that the California red-legged frog has sustained a 75 percent 
reduction in its geographic range in California. Large aggregations of 
greater than 350 adults currently are known from only three areas: 
Pescadero Marsh Natural Preserve in coastal San Mateo County, Point 
Reyes National Seashore in Marin County, and canals west of San 
Francisco International Airport in the San Francisco Bay area (Jennings 
et al. 1992).
    Habitat loss and alteration are primary factors that have 
negatively affected the California red-legged frog throughout its 
range. In the Central Valley of California, over 90 percent of historic 
wetlands have been diked, drained, or filled primarily for agricultural 
development and secondarily for urban development (U.S. Fish and 
Wildlife Service 1978). Much of the wetland habitat lost, such as in 
the San Joaquin Valley, was prime habitat for the California red-legged 
frog (Jennings and Hayes 1984). Wetland alterations, including stream 
channelization, clearing of vegetation, and water diversions that often 
accompanied agricultural development, rendered remaining aquatic sites 
unsuitable for California red-legged frogs. As a result, California 
red-legged frogs on the floor of the Central Valley were eliminated 
probably sometime before 1960 (Jennings et al. 1992). Remaining 
aggregations in drainages around the Central Valley became isolated and 
fragmented.
    Historically, urbanization with its associated roadway, stream 
channelization, and large reservoir construction projects also has 
significantly altered or eliminated California red-legged frog habitat, 
with the greatest impact occurring in southern California. South of the 
Tehachapi Mountains in southern California, the California red-legged 
frog remains at only 4 of over 80 sites where it was found historically 
(Jennings et al. 1992). No California red-legged frogs were found 
during amphibian surveys in 1993 in Cleveland National Forest in 
southern California (J. Stephenson, pers. comm., 1993).
    Urbanization poses a significant threat to the California red-
legged frog. On the central California coast and south San Francisco 
Bay area, the Service is aware of numerous proposed residential 
developments that would degrade known California red-legged frog 
habitat either directly through on-site degradation of the stream 
environment or indirectly through instream flow reductions to 
accommodate new urban growth (U.S. Fish and Wildlife Service unpubl. 
data). These projects include the East County Area Plan in Alameda 
County, which involves development of up to 52,000 acres, and projects 
currently proposed in the Ruby Hills/Arroyo Del Valle watershed and 
south Livermore Valley; Reservoir Canyon ponds in Santa Clara County; 
Alamo, Shadow, and Brookside Creeks in Contra Costa County; Potrero, 
San Clemente, and San Jose Creeks and the Carmel River in Monterey 
County; and the Santa Ynez River in Santa Barbara County. In San Luis 
Obispo County, one of three counties with numerous drainages supporting 
California red-legged frogs, proposed residential and/or recreational 
development adjacent to San Simeon, Santa Rosa, San Juan, Chorro, and 
Cambria Meadows Creeks and Estrella and Salinas Rivers would degrade or 
eliminate California red- legged frog habitat. Updates to area plans 
for the North Coast, San Luis Obispo, and Paso Robles/Atascadero areas 
in San Luis Obispo County propose rezoning of over 240,000 acres 
primarily for urban development. Between the cities of Ventura and San 
Luis Obispo, development already has eliminated California red-legged 
frogs from at least eight drainages along the coast (Galen B. Rathbun 
and Mark R. Jennings, U.S. Fish and Wildlife Service, in litt., 1993).
    Historic water projects, which accompanied urban and agricultural 
growth, also had a negative effect on California red-legged frogs. 
Construction of reservoirs, such as Lake Oroville, Whiskeytown 
Reservoir, Don Pedro Reservoir, Lake Berryessa, San Luis Reservoir, 
Lake Silverwood, Lake Piru, Pyramid Lake, and Lower Otay Lake, directly 
eliminated California red-legged frog habitat or fragmented remaining 
aggregations (Jennings et al. 1992). Reservoirs also typically are 
stocked with exotic species of fish and the introduced bullfrog (Rana 
catesbeiana). These species often expand into previously isolated 
California red-legged frog habitat. The timing and duration of water 
releases from reservoirs, particularly on the central California coast, 
can render a stream unsuitable for California red-legged frog 
production (M. Jennings, in litt., 1993) or maintain aggregations of 
exotic predators in downstream areas that would normally be dry in 
summer (S. Sweet, in litt., 1993). Hayes and Jennings (1988) found that 
California red-legged frogs generally were extirpated from a drainage 1 
to 5 years after filling of a reservoir. See Factor C below for further 
discussion of exotic predators.
    A variety of proposed water projects threaten remaining California 
red-legged frog populations. Construction of major reservoirs is 
proposed on Los Banos Creek (Merced County), with Orestimba Creek 
(Stanislaus County) as an alternative reservoir site (California 
Department of Water Resources and the U.S. Bureau of Reclamation 1990), 
and on Kellogg Creek (Contra Costa County) (Contra Costa Water District 
1993). These sites represent three of six sites remaining in the 
Central Valley hydrographic basin with known or potential aggregations 
of California red-legged frogs. On the Salinas River on the central 
coast, raising the height of Salinas Dam (Santa Margarita Lake) is 
proposed in San Luis Obispo County. Reservoir construction at this site 
may allow exotic predators access to formerly secure aggregations of 
California red-legged frogs isolated in upper portions of the watershed 
(L. Hunt, in litt., 1993). Other large reservoir projects proposed in 
California red-legged frog habitat include the Upper Nacimiento River 
Project and Arroyo Seco Dam Project in Monterey County. In Santa 
Barbara and Ventura Counties, proposed dams on the Santa Ynez River, 
Sisquoc River, and Sespe Creek also would eliminate or degrade 
California red-legged frog habitat (S. Sweet, pers. comm., 1993).
    Proposed or existing water diversions, well development, or small 
reservoir construction projects to supply residential uses on the 
central coast (e.g., San Simeon, Santa Rosa, Van Gordon, Villa, San 
Luis Obispo, Chorro, Pico, and Little Pico Creeks, Arroyo del Puerta, 
and Arroyo Laguna in San Luis Obispo County; the Carmel and Salinas 
River drainage basins in Monterey County; Canada de Refugio in Santa 
Barbara County) reduce instream flows and, when combined with drought, 
degrade or eliminate riparian habitat and create stressful conditions 
for California red-legged frogs. See Factor E below for additional 
discussion of the effects of drought. Small reservoirs also serve as a 
source of exotic fishes and bullfrogs (G. Rathbun and M. Jennings, in 
litt., 1993). The proposed coastal branch of the State Water Project 
likely would result in a number of adverse effects to California red-
legged frogs in many of the 24 areas receiving State water, including 
(1) altered water regimes in existing and any proposed delivery 
facilities of individual water districts, (2) spills, leaks, 
malfunctions, and operational errors that lead to introduction of 
exotic predators into isolated stream segments currently occupied by 
California red-legged frogs, and (3) indirect effects associated with 
expanded urbanization.
    Storm damage repair and flood control maintenance of streams is a 
widespread and ongoing threat to California red-legged frogs. Routine 
flood control maintenance includes vegetation removal, herbicide 
spraying, shaping of banks to control erosion, and desilting of the 
creek. All of these activities degrade California red-legged frog 
habitat. In San Luis Obispo and Santa Barbara Counties, maintenance 
work is planned for 14 and 11 drainages, respectively. All 25 drainages 
are known to be inhabited by California red-legged frogs. In Santa 
Barbara County, a larger channel maintenance project is proposed for a 
4.5-mile stretch of the Santa Ynez River near Lompoc and a 10-mile 
segment of San Antonio Creek, both of which support California red-
legged frog habitat. Channel maintenance at San Francisco International 
Airport threatens one of the three largest remaining aggregations of 
this subspecies.
    Regular road maintenance activities involving grading in or 
adjacent to California red-legged frog habitat can result in increased 
siltation in the stream. If this siltation occurs during the breeding 
season, asphyxiation of eggs and small California red-legged frog 
larvae can result. On the upper Santa Ynez River and Sespe Creek in Los 
Padres National Forest, Sweet (pers. comm., 1993) observed California 
red-legged frog egg masses smothered with silt.
    Livestock grazing is another form of habitat alteration that is 
contributing to declines in the California red-legged frog. Jennings et 
al. (1992) found livestock grazing to occur at all known historic 
locations of the California red-legged frog in the Central Valley 
hydrographic basin. Livestock grazing also has been implicated as a 
contributing factor in the decline and disappearance of California red-
legged frogs from the lower Salinas River (L. Hunt, in litt., 1993) and 
the San Francisco peninsula (S. Barry, in litt., 1992). Two remaining 
aggregations of California red-legged frogs in the Central Valley 
hydrographic basin (Corral Hollow Ecological Reserve and Frank Raines 
Regional Park) are threatened by sedimentation of aquatic habitats 
either directly or indirectly caused by livestock grazing and off-road 
vehicle use (Jennings et al. 1992). Rathbun (pers. comm., 1993) reports 
that grazing is adversely altering California red-legged frog habitat 
on Pico, Van Gordon, San Simeon, Santa Rosa, Cambria Meadows, and 
Cayucos Creeks in San Luis Obispo County.
    Numerous studies, summarized in Behnke and Raleigh (1978) and 
Kauffman and Krueger (1984), have shown that livestock grazing 
negatively affects riparian habitat. Cattle have a disproportionately 
greater adverse affect on riparian and other wetland habitats because 
they tend to concentrate in these areas, particularly during the dry 
season (Marlow and Pogacnik 1985). Cattle trample and eat emergent and 
riparian vegetation, often eliminating or severely reducing plant cover 
(Gunderson 1968, Duff 1979). Loss of riparian vegetation results in 
increased water temperatures (Van Velson 1979), which encourage 
bullfrog reproduction (bullfrogs are a predator and competitor of 
California red-legged frogs). Riparian vegetation loss due to cattle 
grazing includes the loss of willows (Duff 1979), which are associated 
with the highest densities of California red-legged frogs (Jennings 
1988b). Cattle grazing also results in increased erosion in the 
watershed (Lusby 1970, Winegar 1977), which results in the 
sedimentation of deep pools (Gunderson 1968) used by California red-
legged frogs and adversely affects aquatic invertebrates (Cordone and 
Kelley 1961), which are common prey items of California red-legged 
frogs.
    Off-road vehicle use adversely affects California red-legged frogs 
in ways similar to livestock grazing. Off-road vehicles damage riparian 
vegetation and increase siltation in pools. Off-road vehicles also 
disturb the water in stream channels and may crush eggs, larvae, 
juveniles or adults. California red-legged frogs were eliminated either 
all or in part by off-road vehicle activities at the Mojave River above 
Hesperia, at Rincon Station on the San Gabriel River, and at Piru Creek 
above Pyramid Lake (M. Jennings, pers. comm., 1993).
    Timber harvest threatens California red-legged frogs through loss 
of riparian vegetation, which is needed for cover and water temperature 
regulation, and increased erosion in the watershed, which fills pools 
with sediment and smothers egg masses. In Santa Cruz County, timber 
harvest is proposed adjacent to Adams Creek (Celia Scott, private 
citizen, pers. comm., 1993), 1 of 12 remaining streams in the county 
that support California red-legged frogs.
    B. Overutilization for commercial, recreational, scientific, or 
educational purposes. Records of harvesting California red-legged frogs 
for food date back to an account by Lockington (1879) of the commercial 
harvest of this species for the San Francisco market. From 1890 to 
1900, the California red-legged frog supported a significant commercial 
fishery (Smith 1895) with about 80,000 frogs harvested annually 
(Jennings and Hayes 1984). Counties surrounding San Francisco Bay 
provided the bulk of the frog harvest in the early to mid 1890s, with 
the Sacramento and San Joaquin Valleys increasing in importance by the 
end of the decade (Chamberlain 1898, Jennings and Hayes 1985). By 1900, 
harvest figures for California red-legged frogs fell dramatically, 
indicating that overharvesting may have occurred. Jennings and Hayes 
(1985) hypothesized that this rapid decline in the California red-
legged frog population was the result of selective harvesting of the 
larger females. Introduction of the bullfrog in California in 1896 was 
probably in response to the dwindling California red-legged frog 
population (Jennings and Hayes 1985).
    Prior to 1950, California red-legged frogs were used sporadically 
for research in high schools and universities. At present, the 
California red-legged frog is sold commercially from suppliers located 
outside California in the pet trade. Because the State of California 
prohibits possession of wild California red-legged frogs, frogs sold in 
the pet trade presumably are reared in captivity (M. Jennings, pers. 
comm., 1993). However, California red-legged frogs occur in isolated 
and fragmented wetland habitat on private property and are at risk from 
vandalism.
    C. Disease or predation. There have been no documented instances of 
disease adversely affecting the California red-legged frog.
    Few data are available on the effect of native predators on the 
California red-legged frog. Bitterns (Botaurus lentiginosus) and black-
crowned night herons (Nycticorax nycticorax) are likely predators of 
adult frogs (Jennings and Hayes 1990). Juvenile California red-legged 
frogs, which are more active diurnally and less wary than adults, may 
be more susceptible to predation by diurnal predators, such as the 
great blue heron (Ardea herodias) and several species of garter snakes 
(Thamnophis sp.) (Fitch 1940, Fox 1952), including the endangered San 
Francisco garter snake (Thamnophis sirtalis tetrataenia) (Barry 1978, 
Wharton et al. 1986). Recent post-metamorphs also may be particularly 
vulnerable to predation by garter snakes, as was found in other species 
of ranid frogs by Arnold and Wassersug (1978).
    Introduced predators of particular concern are the bullfrog, red 
swamp crayfish (Procambarus clarkii), signal crayfish (Pacifastacus 
leniusculus), and several species of fish, including bass (Micropterus 
spp.), catfish (Ictalurus spp.), sunfish (Lepomis spp.), and 
mosquitofish (Gambusia affinis) (Moyle 1973; Hayes and Jennings 1986, 
1988). All species were introduced into California in the late 1800s 
and early 1900s, and through range expansions, reintroductions, and 
transplants have become established throughout most of the state 
(Riegel 1959, Bury and Luckenbach 1976, Moyle 1976).
    Several researchers in central California have noted the decline 
and eventual disappearance of California red-legged frogs once 
bullfrogs become established at the same site (L. Hunt, in litt, 1993; 
S. Barry, in litt., 1992; S. Sweet, in litt., 1993). Moyle (1973) 
attributed the disappearance of California red-legged frogs from the 
San Joaquin Valley and Sierran foothill region primarily to a 
combination of bullfrog predation and competition. All sites in the 
Sierra Nevada mountains that supported California red-legged frogs in 
the 1970s now are inhabited by bullfrogs (M. Jennings, in litt., 1993). 
Over 65 percent of the streams or drainages currently known to support 
California red-legged frogs also are inhabited by bullfrogs, either in 
association with California red-legged frogs or in other portions of 
the drainage. Over the last decade, Jennings (in litt., 1993) has 
observed bullfrogs moving upstream and/or downstream into formerly 
isolated California red-legged frog habitat in a number of drainages, 
including streams in Ventura, Santa Barbara, San Luis Obispo, Merced, 
Stanislaus, and San Mateo Counties. Game fish are introduced into 
drainages by stocking of reservoirs and ponds, dispersal and 
colonization, conveyance of project water from other streams inhabited 
by these exotics, and releases by individuals. At The Nature 
Conservancy Santa Rosa Plateau Reserve in Riverside County (the only 
site south of the Santa Clara River supporting California red-legged 
frogs), a docent found a school teacher attempting to introduce 
bullfrog tadpoles into the preserve in the 1980s (M. Jennings, in 
litt., 1993). Once established, it is virtually impossible to eliminate 
bullfrogs (M. Jennings, in litt., 1993; Cecil Schwalbe, National Park 
Service, Tuscon, Arizona, pers. comm., 1993; Frank Slavens, Woodland 
Park Zoological Gardens, Seattle, Washington, pers. comm., 1993).
    Bullfrogs prey on California red-legged frogs (Twedt 1993; S. 
Sweet, in litt., 1993) and other amphibians and aquatic reptiles 
(Schwalbe and Rosen 1988). Twedt (1993) documented 4 juvenile red-
legged frogs in the contents of a total of 22 adult bullfrog stomachs. 
He also found a subadult bullfrog in one of the adult bullfrog 
stomachs; this prey item was between the size of an adult male 
(approximately 55 millimeters (2 inches)) and adult female 
(approximately 70 millimeters (3 inches)) red-legged frog, indicating 
that bullfrogs also undoubtedly prey on adult red-legged frogs. 
Bullfrogs may have a competitive advantage over red-legged frogs 
because of their (1) larger size, (2) generalized food habits (Bury and 
Whelan 1984), (3) extended breeding season (Storer 1933), which allows 
for production of two clutches of eggs during a breeding season (Emlen 
1977), (4) apparent olfactory rejection of larvae by predatory fish 
(Kruse and Francis 1977), and (5) diminished activity periods (Woodward 
1983), which also reduces their exposure to predators. Bullfrogs also 
interfere with red-legged frog reproduction. Several researchers have 
noted red-legged frogs in amplexus (mounted on) with bullfrogs 
(Jennings and Hayes 1990; Twedt 1993; M. Jennings, in litt., 1993; 
Stebbins in litt., 1993). However, the extent to which bullfrog 
predation, competition, and reproductive interference adversely affects 
red-legged frogs has not been studied in the field (Hayes and Jennings 
1986). Habitat alterations, including removal of riparian or aquatic 
vegetation, reduced stream flows, and sedimentation of pools, often 
provide conditions detrimental to red-legged frogs but favorable to 
bullfrogs (Hayes and Jennings 1986; Jennings, pers. comm., 1993).
    Hayes and Jennings (1986, 1988) noted an inverse correlation 
between the abundance of introduced fish species and red-legged frogs. 
Aquatic sites where introduced fishes were abundant rarely had native 
ranids, and when present, ranid populations were small. A similar 
negative correlation was reported by Hunt (in litt., 1993) for red-
legged frogs in the Salinas River drainage and by Moyle (1973) for the 
foothill yellow-legged frog (Rana boylii). Stocking of warm water game 
fish is often included as a mitigation measure in proposed reservoir 
projects. Results of a recent study indicate that, despite their small 
size, mosquitofish do prey on and incapacitate red-legged frog tadpoles 
by eating their fins. This mosquitofish predation may be more 
significant than predation by bluegill (Lepomis macrochirus) or 
bullfrogs (Michael Soule and Randy Schmieder, University of California, 
Santa Cruz, pers. comm., 1993). Mosquitofish have become established 
statewide and are stocked routinely by mosquito abatement districts as 
a control measure (Moyle 1976). The demonstrated adverse effects and 
widespread distribution of alien fishes on red-legged frogs indicate 
that fish introductions are one of the primary threats to the survival 
of the species.
    D. The inadequacy of existing regulatory mechanisms. In 1972, the 
California Fish and Game Commission amended its sport fishing 
regulations to prohibit take or possession of California red-legged 
frogs (Bury and Stewart 1973). This law, however, provides no 
protection for habitat of the California red-legged frog. The 
California red-legged frog also is classified as a ``Species of Special 
Concern'' in California (Steinhart 1990). This designation, however, 
provides no special, legally mandated protection.
    The Clean Water Act (section 404) is the primary Federal law that 
could provide some protection for aquatic habitats of the California 
red-legged frog if the habitats are determined by the U.S. Army Corps 
of Engineers (Corps) to be jurisdictional areas (i.e., waters of the 
United States). Under section 404, nationwide permits, which undergo 
minimal public and agency review, can be issued for projects involving 
less than 10 acres of wetlands above the headwaters (i.e., streams with 
less than 5 cubic feet per second (cfs) mean annual flow) or for 
isolated waters, unless a listed species may be adversely affected. 
Many aggregations of California red-legged frogs occur in isolated 
wetlands and coastal streams that may have mean annual flows less than 
5 cfs. Individual permits, which are subject to more extensive review, 
could be required for projects that have more than minimal impacts to 
waters of the United States. The Clean Water Act does not afford any 
special protection for candidate species. However, if the California 
red-legged frog is listed, the Corps would be required by section 7 of 
the Act to consult and obtain the concurrence of the Service prior to 
the authorization of any section 404 permit.
    Federal lands, including those of the Forest Service, National Park 
Service, Bureau of Land Management, and Department of Defense, 
encompass approximately 10 percent of the current known range of the 
California red-legged frog. Multiple land use management, as currently 
practiced by the Forest Service, Bureau of Land Management, and 
National Park Service, does not provide long-term protection for the 
California red-legged frog.
    E. Other natural or man-made factors affecting its continued 
existence. Four consecutive years of drought in California (1986-1990) 
severely affected remaining California red-legged frogs in the Sierra 
foothills. According to the petitioners, several thousand hours of 
field surveys have revealed only one California red-legged frog since 
1985 (Jennings et al. 1992). Many sites in intermittent streams that 
held California red-legged frogs before the drought were completely dry 
during field surveys. Sites still holding pools of water had water 
levels so low that access by predators was enhanced. Livestock grazing 
at many sites exacerbated effects of the drought by limiting or 
preventing riparian habitat regeneration (Jennings et al. 1992). 
Jennings et al. (1992) concluded that California red-legged frogs have 
been extirpated from the Sierra Nevada foothills or are extremely rare 
and vulnerable. Amphibian surveys of Sierran National Forests in 1992 
revealed no California red-legged frogs (David Martin, University of 
California, Santa Barbara, pers. comm., 1993).
    On the central California coast, drought also may play a role in 
decreased California red-legged frog reproduction where frogs occur in 
coastal lagoons. At Pescadero Marsh Natural Preserve, Jennings and 
Hayes (1990) found that many dead egg masses in a portion of the marsh 
likely were killed by excessive (> 4.5 parts per thousand) salinity 
levels. High salinities in the marsh were attributed to drought 
conditions in the watershed. Rathbun et al. (1991) attributed the 
absence of California red-legged frogs in lower Santa Rosa Creek and 
lagoon in San Luis Obispo County to overallocation of instream flows 
exacerbated by the drought. Increased salinities were recorded in 
several other coastal lagoons during the drought years (C. Swift and K. 
Worcester, pers. comm. in Jennings et al. 1992). In 1993, Jennings 
(pers. comm., 1993) reported the loss of California red-legged frog egg 
masses from increased salinity in Arroyo Laguna in San Luis Obispo 
County. Because significant numbers of California red-legged frogs 
occur in coastal lagoons on the central California coast, drought has 
the potential to severely reduce production of California red-legged 
frogs over a significant portion of their remaining range.
    Reservoirs provide persistent habitat for bullfrogs during drought. 
Once rains return, bullfrogs recolonize former habitat as reservoir 
levels rise. Reservoirs, however, with their steep sides and lack of 
critical riparian vegetation, are structurally unsuitable for the 
California red-legged frog.
    Periodic wildfires may adversely affect California red-legged frogs 
by causing direct mortality, destroying streamside vegetation, or 
eliminating vegetation that protects the watershed. The 1991 Lions Fire 
on upper Sespe Creek in the Los Padres National Forest destroyed known 
California red-legged frog habitat (S. Sweet, pers. comm., 1993). 
Following the fire, extensive erosion in the watershed also negatively 
affected California red-legged frogs (S. Sweet, pers. comm., 1993).
    Extensive flooding has been implicated by Jennings and Hayes (in 
press) as a significant contributing factor in the extirpation of the 
California red-legged frog from desert drainages of southern 
California. For example, in the Mojave River drainage, no verifiable 
records or sightings exist of California red-legged frogs after 1968 
(Jennings and Hayes in press). The disappearance of this species from 
the drainage coincided with a catastrophic flood event in the Mojave 
River in the winter of 1968-1969.
    The high degree of fragmentation of remaining California red-legged 
frog habitat makes this subspecies especially vulnerable to random 
extinction events and to loss of genetic variability. Small population 
size increases rates of inbreeding and may allow expression of 
deleterious recessive genes occurring in the population (known as 
``inbreeding depression''). Loss of genetic variability, through random 
genetic drift, reduces the ability of small populations to respond 
successfully to environmental stresses. In the remaining vestiges of 
its former habitat and with its potentially reduced genetic 
variability, the California red-legged frog is vulnerable to random or 
stochastic events, such as fluctuations or variations of annual weather 
patterns (as discussed above), availability of food, predation and 
associated demographic uncertainty, or other environmental stresses. 
With only three areas currently supporting over 350 adults, all 
remaining populations of the species are considered vulnerable to 
stochastic threats.
    The Service carefully has assessed the best scientific and 
commercial information available regarding the past, present, and 
future threats faced by the California red-legged frog in determining 
to propose this rule. Based on this evaluation, the preferred action is 
to list the California red-legged frog (Rana aurora draytonii) as 
endangered. This subspecies has been extirpated from 75 percent of its 
former range. Seventy-seven percent of remaining aggregations currently 
are threatened by one or more factors, including (1) introduction of 
exotic predators and competitors, (2) urban encroachment, (3) 
construction of large and small reservoirs, water diversions and well 
development, (4) flood control maintenance, (5) grazing, and (6) timber 
harvest. Only 44 drainages, with the majority being in Monterey, Santa 
Barbara, and San Luis Obispo Counties, currently provide habitat free 
from the above threats. Fragmentation of habitat, however, renders 
these populations vulnerable to random extinction (stochastic) events. 
For the reasons discussed below, critical habitat is not being proposed 
at this time.

Critical Habitat

    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 propose critical habitat at the time a 
species is proposed to be endangered or threatened. The Service finds 
that designation of critical habitat is not presently prudent for the 
California red-legged frog.
    As discussed under Factor B in the ``Summary of Factors Affecting 
the Species'' section, the California red-legged frog has been and 
continues to be threatened by taking, an activity difficult to control. 
Listing of the frog may result in an increase in the threat of 
vandalism, a concern expressed by the petitioners and other experts (M. 
Jennings, S, Sweet, pers. comms., 1993). California red-legged frogs 
occur in isolated and fragmented wetland habitat on private property 
and are at risk from vandalism. Publication of specific localities, 
which would be required in proposing critical habitat, would reveal 
precise locality data and thereby make the species more vulnerable to 
collection and acts of vandalism, and increase the difficulties of 
enforcement. Protection of this species' habitat will be addressed in 
the recovery process and through the section 7 consultation process. 
Therefore, it would not now be prudent to determine critical habitat of 
the California red-legged frog.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Endangered Species Act include recognition, 
recovery actions, requirements for Federal protection, and prohibitions 
against certain activities. Recognition through listing encourages and 
results in conservation actions by Federal, State, and private 
agencies, groups, and individuals. The Act provides for possible land 
acquisition and cooperation with the States and requires that recovery 
actions be carried out for all listed species. The protection required 
of Federal agencies and the prohibitions against taking and harm are 
discussed, in part, below.
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened and with respect to its critical 
habitat, if any is being designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Section 7(a)(4) of the Act requires Federal agencies to 
confer informally with the Service on any action that is likely to 
jeopardize the continued existence of a proposed species or result in 
destruction or adverse modification of proposed critical habitat. If a 
species is 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 such a species 
or to destroy or adversely modify its critical habitat. If a Federal 
action may affect a listed species or its critical habitat, the 
responsible Federal agency must enter into formal consultation with the 
Service.
    Federal agencies that may be involved as a result of this proposed 
rule are the Bureau of Reclamation, Bureau of Land Management, National 
Park Service, Forest Service, and the Departments of the Army, Navy and 
Air Force. At several parks, the National Park Service has conducted or 
is planning to conduct surveys of California red-legged frogs on park 
property (Daphne A. Hatch, National Park Service, in litt., 1993; James 
Sleznick, National Park Service, in litt., 1992; Gary Fellers, National 
Park Service, pers. comm., 1993). The Forest Service has conducted and 
has ongoing amphibian surveys in many National Forests within the 
historic range of the California red-legged frog (J. Stephenson, pers. 
comm., 1993; D. Martin, pers. comm., 1993). The Bureau of Reclamation 
is cosponsoring a proposed reservoir construction project (Los Vaqueros 
Reservoir) on Kellogg Creek, Contra Costa County (Contra Costa Water 
District 1993). A mitigation and monitoring program is proposed to 
compensate for California red-legged frog habitat losses. The 
mitigation plan includes a bullfrog and exotic fish control program to 
be carried out for the life of the reservoir project (Contra Costa 
Water District 1993). The potential for success of the mitigation plan 
is unknown. The proposed Los Banos Grande reservoir project on Los 
Banos Creek in Merced County, also cosponsored by the Bureau of 
Reclamation, does not provide mitigation specifically for the 
California red-legged frog (Cay Goude, Fish and Wildlife Service, pers. 
comm., 1993). The U.S. Army Corps of Engineers would be involved 
through their permitting authority under section 404 of the Clean Water 
Act. Any of the above mentioned Federal agencies would be required to 
consult with the Service if any action they fund, authorize, or carry 
out is likely to jeopardize the continued existence of the California 
red-legged frog.
    The Act and implementing regulations found at 50 CFR 17.21 set 
forth a series of general prohibitions and exceptions that apply to all 
endangered wildlife. With respect to the California red-legged frog, 
these prohibitions, in part, make it illegal for any person subject to 
the jurisdiction of the United States to take (including harass, harm, 
pursue, hunt, shoot, wound, kill, trap, capture, collect, or attempt 
any such conduct), import or export, transport in interstate or foreign 
commerce in the course of commercial activity, or sell or offer for 
sale in interstate or foreign commerce any listed species. It 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 and threatened wildlife species under certain 
circumstances. Regulations governing permits are at 50 CFR 17.22 and 
17.23. Such permits are available for scientific purposes, to enhance 
the propagation or survival of the species, and/or for incidental take 
in connection with otherwise lawful activities. Requests for 
information on permits should be addressed to the Assistant Regional 
Director, Ecological Services, U.S. Fish and Wildlife Service, 911 NE. 
11th Avenue, Portland, Oregon 97232-4181 (503/231-6241; FAX 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. Comments 
particularly are sought concerning:
    (1) Biological, commercial trade, or other relevant data concerning 
any threat (or lack thereof) to the California red-legged frog;
    (2) The location of any additional populations of the California 
red-legged frog 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 the California red-legged frog;
    (4) Any examples of take or vandalism of California red-legged 
frogs; and
    (5) Current or planned activities in the subject area and their 
possible impacts on the California red-legged frog.
    Any final decision on this proposal 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 Endangered Species Act provides for a public hearing on this 
proposal, if requested. Requests must be received within 45 days of the 
date of publication of this proposal in the Federal Register. Such 
requests must be made in writing and addressed to the Field Supervisor 
of the Sacramento Field Office (see ADDRESSES section).

National Environmental Policy Act

    The Fish and Wildlife Service has determined that an Environmental 
Assessment, as defined under the authority of the National 
Environmental Policy Act of 1969, need not be prepared in connection 
with regulations adopted pursuant to section 4(a) of the Endangered 
Species Act of 1973, as amended. A notice outlining the Service's 
reasons for this determination was published in the Federal Register on 
October 25, 1983 (48 FR 49244).

References Cited

    A complete list of all references cited herein is available upon 
request from the Field Supervisor, Sacramento Field Office (see 
ADDRESSES section).

Author

    The primary author of this proposed rule is Karen J. Miller, 
Sacramento Field Office (see ADDRESSES section), telephone 916/978-
4866.

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, 10080 Stat. 3500, unless otherwise noted.

    2. Section 17.11(h) is amended by adding the following, in 
alphabetical order under Amphibians, to the List of Endangered and 
Threatened Wildlife to read as follows:


Sec. 17.11  Endangered and threatened wildlife

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                      Species                                                    Vertebrate population                                                  
----------------------------------------------------      Historic range          where endangered or      Status    When listed    Critical    Special 
       Common name             Scientific name                                        threatened                                    habitat      rules  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
        Amphibians                                                                                                                                      
Frog, California red-      Rana aurora draytonii...  U.S.A. (CA).............  Entire (excluding         E           ...........           NA         NA
 legged.                                                                        populations in                                                          
                                                                                Humboldt, Trinity, and                                                  
                                                                                Mendocino Cos., CA;                                                     
                                                                                Sonoma Co, CA, north                                                    
                                                                                and west of 38 deg. 30'                                                 
                                                                                N, 123 deg. W; and NV).                                                 
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dated: January 26, 1994.
Mollie H. Beattie,
Director, Fish and Wildlife Service.
[FR Doc. 94-2303 Filed 2-1-94; 8:45 am]
BILLING CODE 4310-55-P