Endangered and Threatened Wildlife and Plants; Determination of Threatened Status for the California Red-Legged Frog
Federal RegisterMay 23, 1996
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AC 34
Endangered and Threatened Wildlife and Plants; Determination of
Threatened Status for the California Red-Legged Frog
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: The U.S. Fish and Wildlife Service (Service) determines
threatened status for the California red-legged frog (Rana aurora
draytonii) pursuant to the Endangered Species Act of 1973, as amended
(Act). The Service originally proposed to list the California red-
legged frog as endangered, but information obtained during the comment
period suggests that this taxon is found in more localities within its
current range than previously identified. The California red-legged
frog is now found primarily in wetlands and streams in coastal
drainages of central California. It has been extirpated from 70 percent
of its former range. The California red-legged frog is threatened
within 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, livestock
grazing, and habitat fragmentation. This rule implements the Federal
protection and recovery provisions afforded by the Act for this
species.
EFFECTIVE DATE: June 24, 1996.
ADDRESSES: The complete file for this rule is available for public
inspection, by appointment, during normal business hours at the U.S.
Fish and Wildlife Service, 2800 Cottage Way, Room E-1803, Sacramento,
CA 95825-1846.
FOR FURTHER INFORMATION CONTACT: Karen J. Miller, at the above address
(916 979-2725).
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. Rana a. draytonii was first described by Baird and
Girard in 1852 from specimens collected at or near the City of San
Francisco in 1841 (Storer 1925, Cochran 1961). The California red-
legged frog is the largest native frog in the western United States
(Wright and Wright 1949),
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ranging from 4 to 13 centimeters (cm) (1.5 to 5.1 inches (in.)) in
length (Stebbins 1985). The abdomen and hind legs of adults are largely
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 (tadpoles) range from 14 to 80 millimeters (mm) (0.6 to 3.1 in.)
in length and the background color of the body is dark brown and yellow
with darker spots (Storer 1925).
The historical range of the California red-legged frog extended
coastally from the vicinity of Point Reyes National Seashore, Marin
County, California, and inland from the vicinity of Redding, Shasta
County, California, 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 (northern Del Norte County). Red-legged
frogs found in the intervening area (southern Del Norte to northern
Marin County) 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 R. a. draytonii and the intergrade zone along the coastal range
(Mark Jennings, National Biological Service, pers. comm., 1993).
California red-legged frogs found in Nevada (Linsdale 1938, Green
1985b) were introduced. This rule does not extend the Act's protection
to any R. aurora in (1) The State of Nevada; (2) Humboldt, Trinity, and
Mendocino counties, California; (3) Glenn, Lake, and Sonoma counties,
California, west of the Central Valley Hydrological Basin; or (4)
Sonoma and Marin counties north and west of the Napa River, Sonoma
Creek, and Petaluma River drainages, which drain into San Francisco
Bay, and north of the Walker Creek drainage, which drains to the
Pacific Ocean.
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 in.) (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 through March with
earlier breeding records occurring in southern localities (Storer
1925). Northern red-legged frogs breed in January to March soon after
the ice melts (Nussbaum et al. 1983). 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 dense, shrubby or
emergent riparian vegetation closely associated with deep (>0.7 meters
(m)) still or slow moving water (Hayes and Jennings 1988). The largest
densities of California red-legged frogs 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 (Jennings and
Hayes 1994b). California red-legged frogs have been found up to 30 m
(98 feet (ft)) from water in adjacent dense riparian vegetation for up
to 77 days (Rathbun et al. 1993, Galen Rathbun, National Biological
Service, in litt., 1994). Rathbun (in litt., 1994) found that the use
of the adjacent riparian corridor was most often associated with drying
of coastal creeks in mid to late summer.
California red-legged frogs disperse upstream and downstream of
their breeding habitat to forage and seek estivation habitat.
Estivation habitat is essential for the survival of California red-
legged frogs within a watershed. Estivation habitat, and the ability to
reach estivation habitat can be limiting factors in California red-
legged frog population numbers and survival.
Estivation habitat for the California red-legged frog is
potentially all aquatic and riparian areas within the range of the
species and includes any landscape features that provide cover and
moisture during the dry season within 300 feet of a riparian area. This
could include boulders or rocks and organic debris such as downed trees
or logs; industrial debris; and agricultural features, such as drains,
watering troughs, spring boxes, abandoned sheds, or hay-ricks. Incised
stream channels with portions narrower than 18 inches and depths
greater than 18 inches may also provide estivation habitat.
Egg masses that contain about 2,000 to 5,000 moderate-sized (2.0 to
2.8 mm (0.08 to 0.11 in.) 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).
California red-legged frogs are often prolific breeders, laying their
eggs during or shortly after large rainfall events in late winter and
early spring (Hayes and Miyamoto 1984). Eggs hatch in 6 to 14 days
(Jennings 1988b). In coastal lagoons, 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 die when exposed to salinities greater than 7.0 parts per
thousand (Mark Jennings, National Biological Service, in litt., 1994).
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 normally is reached at 3 to 4 years of
age (Storer 1925, Jennings and Hayes 1985), and California red-legged
frogs may live 8 to 10 years (Jennings et al. 1992).
The diet of California red-legged frogs is highly variable. Larvae
probably eat algae (Jennings et al. 1992). Hayes and Tennant (1985)
found invertebrates to be the most common food items of adult frogs.
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
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juvenile frogs to be active diurnally and nocturnally, whereas adult
frogs were largely nocturnal. Feeding activity likely occurs along the
shoreline and on the surface of the water (Hayes and Tennant 1985).
The California red-legged frog has sustained a 70 percent reduction
in its geographic range in California as a result of several factors
acting singly or in combination (Jennings et al. 1992). Habitat loss
and alteration, overexploitation, and introduction of exotic predators
were significant factors in the California red-legged frog's decline in
the early to mid 1900s. It is estimated that California red-legged
frogs were extirpated from the Central Valley floor before 1960.
Remaining aggregations (assemblages of one or more individuals, not
necessarily a viable population) 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 prolonged drought. Within the Central Valley hydrographic
basin, only 14 drainages on the Coast Ranges slope of the San Joaquin
Valley and one drainage in the Sierran foothills are actually known to
support or may support California red-legged frogs, compared to over 60
historic locality records for this basin (a 77 percent reduction). The
pattern of disappearance of California red-legged frogs in southern
California is similar to that in the Central Valley, except that
urbanization and associated roadway, large reservoir (introduction of
exotic predators), and stream channelization projects were the primary
factors causing population declines. In southern California, California
red-legged frogs are known from only five locations south of the
Tehachapi Mountains, compared to over 80 historic locality records for
this region (a reduction of 94 percent).
California red-legged frogs are known to occur in 243 streams or
drainages in 22 counties, primarily in the central coastal region of
California. The current number of occupied drainages represents
information obtained during the public comment period and re-evaluation
of Service records. This re-evaluation resulted in the compilation of a
threat matrix for all drainages known to support California red-legged
frogs (U.S. Fish and Wildlife Service 1995). The term ``drainage'' will
be used to describe named streams, creeks, and tributaries from which
California red-legged frogs have been observed. For purposes of this
final rule, a single occurrence of California red-legged frog is
sufficient to designate a drainage as occupied by, or supporting
California red-legged frogs. Monterey (32), San Luis Obispo (36), and
Santa Barbara (36) counties support the greatest number of currently
occupied drainages. Historically the California red-legged frog was
known from 46 counties, but the taxon is now extirpated from 24 of
those counties (a 52 percent reduction in county occurrences). In seven
of the 22 occupied counties (32 percent), California red-legged frogs
are known from a single occurrence. 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 (Rana catesbeiana), bass (Micropterus spp.), and
sunfish (Lepomis spp.)). Only three areas within the entire historic
range of the California red-legged frog may currently support more than
350 adults, Pescardero Marsh Nature Preserve (San Mateo County), Point
Reyes National Seashore (Marin County), and Rancho San Carlos (Monterey
County). The San Francisco Airport drainage location, identified in the
proposed rule as containing over 350 individuals, is now thought to be
nearly extirpated. Threats, such as expansion of exotic predators,
proposed residential development, and water storage projects, occur in
the majority of drainages known to support California red-legged frogs.
Previous Federal Action
On January 29, 1992, the Service received a petition from Drs. Mark
R. Jennings and Marc P. Hayes, and Mr. Dan 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 and a review of
the species' status was initiated. 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 (now known simply as candidates) are species for which the
Service has sufficient 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. On February 2, 1994 (59 FR 4888), the
Service published a proposal to list the California red-legged frog as
an endangered species. Based on new information received during the
comment period on the proposed rule, the Service now determines the
California red-legged frog to be a threatened species.
Summary of Comments and Recommendations
In the February 2, 1994 proposed rule (58 FR 4888) and associated
notifications, all interested parties were requested to submit factual
reports or information that might contribute to development of a final
rule. Appropriate State agencies and representatives, County and City
governments, Federal agencies and representatives, scientific
organizations, and other interested parties were contacted and
requested to comment. Newspaper notices were published in the San
Francisco Chronicle on February 9, 1994, and the Sacramento Bee on
February 10, 1994, both of which invited public comment.
The Service received eight written requests for a public hearing.
Three requests came from the Mosquito and Vector Control Districts of
Glenn, Sutter/Yuba, and Butte counties. Additional requests came from
William Hazeltine, a private consultant; the California Cattlemen's
Association; the Cambria Community Services District; the United
Residential Lot Owners of Cambria, Inc.; and Price, Postel, and Parma,
a Santa Barbara law firm. As a result, the Service published a notice
of public hearing on April 8, 1994 (59 FR 16792), and reopened the
comment period until May 27, 1994. Appropriate State agencies and
representatives, County and City governments, Federal agencies and
representatives, scientific organizations, and other interested parties
were contacted regarding the hearing. A newspaper notice of the public
hearing was published in the Sacramento Bee on April 25, 1994, which
invited general public comment. A public hearing was conducted at the
Radisson Hotel in Sacramento, California on May 12, 1994. Testimony was
taken from 6:00 p.m. to 8:00 p.m. Seventeen individuals testified at
the hearing.
During the comment periods, the Service received 72 comments (i.e.,
letters and oral testimony) from 57 individuals or agencies. Of the 31
commenters that stated a position, 22 (71 percent) supported listing
and 9 (29 percent) did not.
Support for the listing was expressed by one State agency
(California
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Department of Parks and Recreation) and 18 other interested parties.
Three commenters recommended listing the California red-legged frog as
threatened. Opposition to the listing was expressed by two mosquito
abatement or vector control districts and seven other interested
parties. Of the 26 respondents indicating no position on the listing,
several expressed concern regarding the impact of listing.
Written comments and oral statements obtained during the public
hearing and comment periods are combined in the following discussion.
Opposing comments and other comments questioning the rule can be placed
in 10 general groups based on content. These categories of comment, and
the Service's response to each, are listed below.
Issue 1: Insufficiency of Scientific Data
Comment: Several commenters stated that insufficient data are
available to warrant listing of the California red-legged frog. They
suggested that the distribution of the California red-legged frog is
more widespread and that many more sites may exist than were reported
in the proposed rule because surveying within the historic range of the
taxon has not been complete. One commenter suggested that only easily
accessible areas on the coast seemed to have been surveyed and if a
watershed approach had been taken, the range of the species would be
greater than 30 percent of its historical range. Another commenter
suggested that many surveys were done in drought years, which would
bias the data.
Service Response: The Service mapped the current range of the
California red-legged frog based on survey results. Wherever a
watershed was known to support California red-legged frogs, the entire
watershed was included as being within the species' current range. The
only watersheds that were not included in their entirety are those in
the Sierra Nevada where the upper reaches are too high in elevation to
provide habitat for the California red-legged frog, and portions of
watersheds located on the Central Valley floor. In the Coast Ranges,
watersheds lacking information on California red-legged frogs were
included within the current range of the California red-legged frog
from Marin County south to Ventura County.
Over the last 15 years, the petitioners have conducted multiple
surveys, visiting each survey site a minimum of three times, to
determine the status of the California red-legged frog throughout its
entire range. The petitioners rechecked 75 percent of the historic
sites in the coastal region of the range of the California red-legged
frog and all suitable habitat within the species historic range in the
Central Valley and Sierra Nevada foothills including all but one of the
historic sites. This site was surveyed by another herpetologist, Dave
Martin (Jennings, pers. comm., 1995). In surveying suitable habitat,
access to some areas was denied by private landowners. Even so,
surveyors were able to obtain access to all major drainages within
their survey area (Jennings, pers. comm., 1995). Many of the surveys
were conducted between 1986 and 1990, which were considered drought
years. However, in the majority of cases reasons other than drought
were considered responsible for the absence of frogs (Jennings, pers.
comm., 1995). Where drought was thought to be the case, repeat surveys
were performed in subsequent wet years (Jennings, pers. comm., 1995).
Approximately half of the sites surveyed were along roadsides and
easily accessible. The remaining sites were difficult to access, often
requiring strenuous hikes (Jennings, pers. comm., 1995). Surveying by
the petitioners and others is ongoing in many portions of the State.
Surveys conducted by other researchers support the conclusions of
the petitioners. Extensive surveying has been conducted in years with
and without drought conditions in Sierran national forests by David
Martin (University of California, Santa Barbara,, pers. comm., 1994);
Santa Clara County and the foothills of the western Sierra Nevada
between Modesto and Fresno by the Coyote Creek Riparian Station (in
litt., 1993); the Sacramento Valley, San Joaquin Valley and inner Coast
Ranges by the University of California at Davis (H. Bradley Shaffer,
University of California, Davis, in litt., 1994); Santa Cruz County by
the University of California at Santa Cruz (Nauman 1992); Santa Cruz
and San Mateo counties (Mike Westphal, Coyote Creek Riparian Station,
1995), and the Point Reyes Peninsula by the National Park Service (Gary
Fellers, National Biological Service, in litt., 1994).
As a result of these surveys and additional information received
during the public comment period following publication of the proposed
rule, 54 new localities of California red-legged frogs were identified.
The majority of these sightings, however, are within the current range
of the California red-legged frog as identified in the proposed rule.
The exceptions are the discovery of California red-legged frogs in the
Sierran foothills (Butte County, Pinkard Creek), the Transverse
mountain range (Los Angeles county near Palmdale), Sulphur Springs
Creek in Solano County, and Mine Creek in Fresno County; the latter two
representing minor range extensions to the east. The Service is
confident that the Central Valley floor, Sierra Nevada foothills, and
southern California (south of the Tehachapi Mountains) have been
surveyed sufficiently to draw the conclusion that California red-legged
frogs have been extirpated or nearly extirpated from these regions.
These three regions comprise over 70 percent of the California red-
legged frog's historic range.
Section 4(b)(1)(A) of the Act requires that a listing determination
be based on the best scientific and commercial data available. The
Service bases this listing determination on data collected over a
period of 15 years by the petitioners and numerous other qualified
herpetologists. All data indicate a downward trend in the range of the
California red-legged frog and a preponderance of small, fragmented
aggregations of frogs. The viability of the remaining California red-
legged frog aggregations is threatened by numerous factors which are
discussed in detail in this rule. The Service maintains, therefore,
that sufficient data are available to warrant listing the California
red-legged frog. However, because the Service received significant
additional information on locations of California red-legged frog
aggregations within their current range during the comment period,
listing the taxon as threatened rather than endangered is deemed more
appropriate.
Comment: Another commenter stated that the conclusion in the
proposed rule that 75 percent of the species' remaining range is
threatened by one or more factors has no basis in scientific fact and
is not supported by any substantial scientific evidence.
Service Response: The proposed rule stated that the California red-
legged frog has been extirpated from 75 percent of the historic range
of the taxon. Because of the inclusion of 54 additional streams or
drainages known to support California red-legged frogs, the final rule
has been revised to state that extirpation has occurred in 70 percent
of the historic range. The commenter misinterpreted the information in
the proposed rule. The estimate of extirpated range is based on
information published in the literature and presented to the Service by
the petitioners and other herpetologists, survey biologists, and
consultants.
Comment: One commenter stated that an article in the March 1, 1994,
San Ramon Valley Times reported that the East Bay Regional Park
District had not
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surveyed for frogs on its properties. Given that the District comprises
over 75,000 acres, the commenter believed that this lack of information
was a significant data gap.
Service Response: East Bay Regional Park District biologists and
private consultants in 1990, 1993, and 1994 surveyed an estimated 95
percent of District properties that could contain California red-legged
frog habitat (Joseph DiDonato, East Bay Regional Park District, pers.
comm. and in litt., 1994; Karen Swaim, LSA Associates, Inc., in litt.,
1994). California red-legged frogs were found in 5 of 53 District
parks. Included in the survey results were 8 streams or drainages not
previously known to be inhabited by California red-legged frogs.
Comment: One commenter stated that the information on California
red-legged frog locations in Alameda County is probably not complete.
The commenter contended that California red-legged frogs are probably
not as rare in Alameda County as purported in the proposed rule.
Service Response: California red-legged frogs are known from 21
drainages in the county. Many other drainages in the county that have
been surveyed by the East Bay Regional Park District and LSA
Associates, Inc. harbor only bullfrogs. Of the 22 counties known to
support aggregations of California red-legged frogs, Alameda County
ranks ninth in total number of drainages supporting the taxon. Over
half of the known frog aggregations in the county, however, are
threatened by various factors including exotic predators, urban
development, off-road vehicles, and grazing. While it is possible that
some California red-legged frog locations have yet to be discovered,
the Service believes it is unlikely that California red-legged frogs
inhabit more than the 21 known drainages in Alameda County.
Comment: One commenter stated that the Service's data on locations
of California red-legged frogs does not match information contained in
the California Department of Fish and Game Natural Diversity Database
(NDDB).
Service Response: The researchers who petitioned the Service to
list this species and the Service have reviewed all data available from
the NDDB regarding locations of California red-legged frogs. The NDDB
currently contains approximately 122 records of California red-legged
frogs. The petitioners have determined current and historic range of
the taxon from 1,205 museum records and 250 records from other sources
coupled with extensive field checking of records. All locations
identified in the NDDB prior to 1992 were field checked by the
petitioners. All new locations identified in the NDDB from 1992 to the
present have been added to the Service's analysis of the current range
of the California red-legged frog. These additional records have not
appreciably extended the currently known range of the taxon.
Comment: Several commenters noted that the proposed rule indicated
uncertainty in biology, life cycle, habitat requirements, and predators
of the California red-legged frog, including identifying where frogs
overwinter, where post-metamorphic frogs feed, what larvae eat, and
site specific predators. The commenters believed that listing of the
taxon was not warranted until these data gaps were filled.
Service Response: The Service has relied on the best available
scientific and commercial data in making this listing determination.
The Service concurs that many aspects of the biology, predator-prey
interactions, and microhabitat requirements of the California red-
legged frog are not completely understood. This is true for most
species of wildlife, including common species that have been studied
extensively. Sufficient knowledge of the biology and habitat
requirements of the California red-legged frog exists to identify
suitable habitats for the taxon, and document population sizes,
threats, and its status over time. It is this latter information along
with the scientific and commercial information that is used in
determining whether or not to list a species under section 4(a) of the
Act. A complete understanding of the biology and microhabitat
requirements of a listed species are most important in the recovery
process. However, a significant delay in listing a species due to
large, long-term biological or ecological research efforts could
compromise the survival of the California red-legged frog.
Comment: Several commenters stated that the proposed rule cites
livestock grazing as a major factor in the decline of the California
red-legged frog, but fails to offer site-specific examples of habitat
degradation and ``take'' of the species as a result of grazing. One
commenter thought that the Service, therefore, could not restrict
grazing practices in any way if the species is listed.
Service Response: The proposed rule includes livestock grazing as
one of many factors affecting the California red-legged frog, and ranks
it as a contributing factor, rather than as a major factor. No site
specific studies have been done that document the decline and
disappearance of California red-legged frogs once grazing is introduced
into an area. Most evidence on the effects of grazing on the California
red-legged frog is circumstantial. However, extensive research has been
done on the effects of livestock grazing on the aquatic environment. As
stated in the proposed rule, the petitioners found that grazing
occurred at all historic sites known to support California red-legged
frogs in the Central Valley hydrologic basin. Combining this
information with information about the habitat preferences of the
California red-legged frog leads to the logical conclusion that
grazing, where it has dramatically altered California red-legged frog
habitat, has played a role in the decline of this taxon.
Comment: One commenter stated that the petition to list the
California red-legged frog relies heavily on personal observations,
personal communications, and unpublished data. Although the Service is
required to base listings on the ``best available data'', the commenter
believed that such information did not meet the definition of
scientific data because they would be impossible to verify. Three
commenters recommended that the proposed listing action be halted and a
comprehensive, unbiased scientific review of the status of the
California red-legged frog be initiated and published.
Service Response: The researchers who petitioned the Service to
list the California red-legged frog are acknowledged experts on this
taxon as evidenced by numerous peer reviewed publications on the
subject. The majority of the personal observations cited in the
petition refer to specific aspects of California red-legged frog
biology, which is relevant to the species' management, but less
important in determining species' status. Many of the references to
unpublished data in the petition refer to distribution and status
information that had been collected by the petitioners as part of their
ongoing research to follow the status of the California red-legged
frog. Much of their status information is supported by surveys
conducted by numerous other qualified herpetologists. The Service,
therefore, finds that the data presented by the petitioners are
credible and have been verified by other experts in the field.
Comment: Several commenters requested that prior to listing the
California red-legged frog, the Service quantify impacts to the various
life stages of the frog caused by storm damage repair, flood control
efforts, reservoir creation, diking and ditching,
[[Page 25818]]
regular road maintenance, disease, livestock grazing, off-road vehicle
use, timber harvest, predation by native and non-native predators,
competition, ultraviolet radiation, water quality, agricultural
practices, recreation, reproductive interference, drought, wildfires,
flooding, and natural population fluctuations.
Service Response: Section 4(a)(1) of the Act requires the Service
to evaluate threats to the species. The Service is unable to quantify
how each of the above individual threats has impacted the California
red-legged frog. Many threats work synergistically to cause population
declines. Thus, the effect of each threat cannot be quantified
separately. The above factors are believed to contribute to significant
population declines. Completing research in all these areas prior to
listing the California red-legged frog could seriously compromise its
survival because of lengthy time periods needed to quantify impacts.
Further research in these areas, however, would aid the Service in
future recovery actions for this species.
Comment: One commenter recommended that the Service delineate the
current range and habitat locations of the California red-legged frog
in San Joaquin County prior to listing.
Service Response: The Service has delineated the current range and
specific habitat locations of California red-legged frogs in San
Joaquin County. Two locations of the California red-legged frog occur
in San Joaquin County, both in western portions of the county. The
distribution map for the California red-legged frog includes all
portions of western San Joaquin County that lie on the east slope of
the coast range, west of Highway 580.
Comment: One commenter recommended that the Service quantify
California red-legged frog population numbers in lotic and lentic
habitat and establish management and recovery programs for each habitat
type prior to listing the taxon.
Service Response: A recovery plan will be prepared for the
California red-legged frog after the taxon is listed. Completion of the
above recommended research would be most appropriate during the
recovery process for the California red-legged frog.
Issue 2: Causes for California Red-Legged Frog Decline
Comment: Several commenters suggested that ultraviolet-B (UV-B)
radiation or estrogen mimics, which have been implicated in the current
observed worldwide decline in amphibians, may be significant causes of
observed declines in the range and numbers of California red-legged
frogs.
Service Response: The Service has reviewed the paper by Blaustein
et al. (1994) regarding the possible effect of UV-B radiation on the
eggs of three amphibian species, the Pacific treefrog (Pseudacris
regilla), western toad (Bufo boreas), and Cascade frog (Rana cascadae).
Our review focused on results reported for the Cascade frog, because
this species is most closely related to the California red-legged frog.
Results of tests on Cascade frog eggs from two sites showed mixed
results. One site showed that hatching success of R. cascadae was
greater under sunlight lacking UV-B than under unfiltered sunlight. At
the second site, however, the hatching success under UV-B blocking
filters was not significantly different from success under unfiltered
sunlight. Thus, these data do not present sufficient evidence of a
correlation between UV-B radiation and hatching success in the related
Cascade frog.
Because UV-B radiation would have greater adverse effects at higher
elevations, the Cascade frog, which is a higher elevation species than
the California red-legged frog, would be expected to be more severely
affected by UV-B radiation, if indeed this is an important factor.
Also, because the California red-legged frog attaches its egg masses to
aquatic vegetation and prefers aquatic habitats with overhanging
vegetation, the effects of UV-B radiation would be expected to be less
than for the Cascade frog, whose eggs are typically laid in shallow
open water (Nussbaum et al. 1983). In addition, the majority of the
observed decline in the California red-legged frog occurred prior to
the late 1970's, which is when noticeable declines in amphibian species
began in western North America (M. Jennings, pers. comm, 1994).
A number of recent studies address certain contaminants that
disrupt biological processes by mimicking the effects of naturally
produced hormones, such as the female hormone estrogen (Raloff 1994).
This phenomenon has been implicated in the recent worldwide decline in
amphibians. Several studies have been done on reptiles, including the
American alligator (Alligator mississippiensis) and red-eared slider
turtle (Pseudemys scripta elegans). To our knowledge, no studies have
been done on amphibians. The potential effects of estrogen mimics on
California red-legged frogs are unknown. In addition, the majority of
the observed decline in the California red-legged frog occurred prior
to the late 1970's, which is when noticeable declines in amphibian
species began in western North America (M. Jennings, pers. comm, 1994).
Comment: Several commenters stated that evidence suggesting
mosquitofish (Gambusia affinis) are significant predators of California
red-legged frog larvae is not strong. The commenters stated that
infrequent co-occurrence of fish and frogs does not explain potential
causation. Other factors may be involved in population decline
including microhabitat features of wetlands, which cannot be
successfully duplicated in a laboratory setting. Also in a natural
setting, the vulnerable stage for California red-legged frog tadpoles
(February through April) normally does not coincide with the time of
year when mosquitofish numbers are high. Microhabitat usage may not
overlap. The commenters pointed out that there are sites where
mosquitofish and California red-legged frogs coexist. One commenter
objected to the mosquitofish being included as a verified predator of
California red-legged frogs and especially as an organism more harmful
than introduced centrarchid fishes or bullfrogs.
Service Response: The Service is aware of only one study that has
indicated that in laboratory settings mosquitofish prey on the larvae
of California red-legged frogs (Schmieder and Nauman 1994). However,
there is a strong correlation between the absence of California red-
legged frogs and the presence of mosquitofish in the field. The Service
is aware of several sites where mosquitofish and California red-legged
frogs are currently coexisting. This evidence suggests that the
relationship between mosquitofish and California red-legged frogs is
complex. Additional research clearly is needed to more fully understand
how these two species interact. The final rule has been revised to
reflect current knowledge on this issue. The Service cannot determine
whether mosquitofish are harmful to California red-legged frogs.
Comment: Several commenters disagreed that mosquitofish could be
significant predators of California red-legged frogs. They cited
observations in mosquitofish ponds of mosquitofish numbers decreasing
as a result of infestations by bullfrogs. These commenters noted that
no predation of bullfrog tadpoles by mosquitofish was observed.
Service Response: Mosquitofish would not be expected to prey on
larval bullfrogs because of the apparent olfactory rejection
(unpalatability) of bullfrog larvae by predatory fish (Kruse and
Francis 1977). California red-legged
[[Page 25819]]
frogs lack this olfactory rejection effect, and, therefore, cannot be
compared to bullfrogs (Schmieder and Nauman 1994).
Comment: One commenter pointed out that widespread, large scale use
of mosquitofish in California began in the mid to late 1970's, and
therefore, could not be responsible for the extirpation of California
red-legged frogs from the Central Valley floor because frogs were
extirpated from this region before 1960.
Service Response: The Service concurs that mosquitofish were not a
major factor in the decline and disappearance of California red-legged
frogs from the Central Valley floor. The proposed and final rules point
to overharvest combined with the loss of over 3,800,000 acres of
wetlands as the major reasons for extirpation of California red-legged
frogs from the valley floor (Frayer, et al. 1989). However, significant
introductions of mosquitofish began in the Central Valley as early as
1922 (Moyle 1976). Thus it is possible that mosquitofish played a role
in the decline of California red-legged frogs on the Central Valley
floor.
Comment: Two commenters stated that mosquitofish are not
significant predators of California red-legged frogs because the two
species coexist in wetlands in Shasta and Colusa counties.
Service Response: California red-legged frogs were extirpated from
Shasta and Colusa counties before 1960 (Jennings et al. 1992).
Comment: Several commenters provided more specific or additional
information on threats to California red-legged frogs within their
current range. Several commenters provided information regarding
potential threats, including road kills, current harvesting of
California red-legged frogs for food, construction activities, and poor
management of flood control basins.
Service Response: These comments have been noted and included in
this final rule.
Comment: One commenter stated that massive predation by introduced
predators, not grazing, is in large part responsible for any observed
population declines in the California red-legged frog. Similarly,
another commenter stated that the decline and disappearance of
California red-legged frogs in the foothill portions of Madera, Fresno,
and Mariposa counties were due to dispersal of bullfrogs into stock
ponds, and not due to grazing. The commenter stated that California
red-legged frogs coexisted with grazing until about 1940, when
bullfrogs were introduced into the San Joaquin Valley.
Service Response: Of the identified threats facing the California
red-legged frog, introduced predators, including bullfrogs, are
considered to be a significant and widespread threat. Over 50 percent
of streams and drainages inhabited by California red-legged frogs are
known to support bullfrogs or other exotic predators in some portion of
that drainage. Grazing, however, can threaten the California red-legged
frog where grazing pressure results in dramatic changes in riparian and
wetland habitat. As discussed in this final rule, California red-legged
frogs generally prefer densely-shaded wetland habitats, whereas
bullfrogs prefer more open wetland habitats. Overgrazing in riparian
areas, therefore, exacerbates the threat of bullfrog expansion by
creating habitat bullfrogs prefer.
Comment: One commenter stated that profitable livestock operations
and high quality riparian habitat areas are not mutually exclusive. The
commenter points to Point Reyes National Seashore as an example of
where cattle grazing and California red-legged frogs successfully
coexist. The commenter stressed that livestock grazing is the only
economic activity in the region that provides large contiguous areas of
open space.
Service Response: The Service concurs that properly managed
livestock grazing can be compatible with preservation of California
red-legged frog populations. California red-legged frogs and cattle
grazing are able to coexist at Point Reyes National Seashore because
the National Park Service maintains tight control over grazing pressure
(Gary Fellers, National Biological Service, pers. comm., 1994). The
Service acknowledges that preservation and proper management of open
space, especially in riparian areas, is a fundamental requirement in
the survival and recovery of the California red-legged frog.
Comment: One commenter stated that the single most devastating
change in wildlife habitat in California in the last 200 years has been
urbanization. The commenter thought that the proposed rule had not
given this factor proper recognition, but instead condemned activities
such as livestock grazing.
Service Response: The proposed rule and this final rule do not
single out livestock grazing as the greatest threat to the California
red-legged frog, but instead discusses all factors known or likely to
threaten California red-legged frog populations. The proposed and final
rules list numerous proposed developments that threaten remaining
populations of California red-legged frogs. The Service believes
urbanization, as well as agriculture, have caused substantial changes
in wildlife habitat in California. This is especially the case in the
Central Valley, which historically was the stronghold of the California
red-legged frog.
Comment: Several commenters stated that climatic conditions (i.e.,
drought and above average rainfall events) were more to blame for
California red-legged frog declines than human activities, including
timber harvest and historic commercial harvest of the California red-
legged frog itself. One commenter noted that dramatic declines in
historic frog harvest information could indicate that the species is
subject to wide variation in population numbers due to climatic
conditions rather than an indication of overharvest. The commenter
requested that an historical survey of the variations in population
numbers due to climatic changes be undertaken prior to publication of a
final rule.
Service Response: The rule includes a discussion of natural
factors, such as drought and heavy rainfall events, that are known to
adversely affect California red-legged frog populations. It is
difficult to separate the effects of natural events from human
activities when attempting to determine the cause for a population's
decline in a particular area. A single factor is seldom the cause of
the decline of a species. Many of the factors discussed in the proposed
rule and this final rule work synergistically. Regardless of which
factors resulted in historic population declines, California red-legged
frog populations in the Central Valley and Sierra Nevada, in
particular, could not rebound from this decline because at the same
time their wetland and riparian habitat was being converted to
agricultural land and urban areas.
Populations of most species are cyclic in nature, responding to
such natural factors as weather events, disease, and predation. Natural
events, however, including long-term drought or extreme rainfall, have
less of a negative effect overall on a species when that species is
widely and continuously distributed. Where populations are small,
fragmented, or isolated by various human-related factors including
habitat loss, water development, and water diversion, these populations
are more vulnerable to extirpation by stochastic or random events and
cumulative effects.
It is likely that over time, California red-legged frogs
experienced wide variations in population size as a result of climatic
events. A historical survey dating back to the early 1900's focusing on
the variation in frog population
[[Page 25820]]
numbers due to climatic changes is not possible because no range wide
population information was collected on the California red-legged frog
dating back that far. If such data existed, conclusions drawn from such
an historical survey would be tenuous. The many adverse human factors
that have contributed to California red-legged frog population declines
since 1900 would cloud any analysis of the effects of drought or high
rainfall events.
Comment: One commenter disagreed with the conclusion that pre-1900
overharvesting of the California red-legged frog in the Central Valley
led to their decline. The commenter stated that other known historical
factors were not cited in the proposed rule.
Service Response: No studies were conducted in the late 1800's or
early 1900's documenting the cause or causes of declines in California
red-legged frog populations in the Central Valley. Extremely high
numbers of California red-legged frogs reported in the San Francisco
markets followed by a collapse of the market around the turn of the
century strongly suggests that commercial harvesting had a significant
effect on California red-legged frog numbers. The Central Valley, and
particularly the San Joaquin Valley, were reported at the time to be
prime habitat for the California red-legged frog. The proposed rule and
this final rule reported all known historical factors that may have
contributed to the decline of California red-legged frogs in the
Central Valley. Overharvesting was certainly not the only factor
impacting California red-legged frog populations. Conversion of over
3,800,000 acres of wetland and riparian habitats in the Central Valley
to agricultural land and urban areas began during the same period,
resulting in the elimination of California red-legged frogs from the
valley floor before 1960.
Comment: Several commenters stated that many of the urban
development projects referred to in the proposed rule in the Central
Coast region may or may not be constructed during the next 5 or 10
years.
Service Response: The Service recognizes that all projects proposed
are not necessarily completed. This may be due to lack of proper
permits necessary for construction, or interruption of planning
efforts. The fact that projects have been proposed presents a future
threat to California red-legged frog aggregations in the central coast
region, especially if these projects result in direct or indirect
riparian habitat degradation.
Comment: One commenter stated the proposed rule incorrectly
includes the Cambria Meadows drainage as an area where California red-
legged frog habitat has been directly degraded through stream
reductions to accommodate new urban growth.
Service Response: This final rule states that proposed urban and/or
recreational development could degrade or eliminate California red-
legged frog habitat in Cambria Meadows Creek.
Comment: One commenter thought that support of the proposed listing
appeared to rely heavily on conditions reported for the north coast of
San Luis Obispo County.
Service Response: Neither the proposed rule nor this final rule
rely heavily on conditions reported for the north coast of San Luis
Obispo County in determining the need to list the California red-legged
frog. San Luis Obispo County contains the third highest number of
drainages known to support California red-legged frogs. Although
California red-legged frog aggregations in streams in the county are
threatened by a variety of factors, many other counties have comparable
threats that are reported in the proposed and final rule.
Comment: Several commenters were concerned about the accuracy of
the conclusions drawn by Rathbun et al. (1991) as cited in the proposed
rule regarding the combined effects of water extraction and drought on
populations of California red-legged frogs in lower Santa Rosa Creek.
Numerous commenters presented data both to support and refute the
hypothesis that water extractions from Santa Rosa Creek have
significantly changed its hydrology.
Service Response: The Service recognizes that controversy exists
regarding the environmental effects of water extraction from Santa Rosa
Creek. The information and data presented by the many commenters on
this subject will be thoroughly reviewed by Service field biologists
during recovery planning efforts and when consulting on any proposed
projects that could adversely affect California red-legged frogs in
Santa Rosa Creek.
Ground water and surface water supplies in Santa Rosa Creek are
finite. Unchecked water extraction may exceed input and significantly
reduce the availability of riparian and aquatic habitat for California
red-legged frogs in the future. Drought accentuates the effect, and if
not considered in water planning, overallocation of stream flows and
overdraft of groundwater resources combined with long-term drought
could result in permanent elimination of California red-legged frogs
from all or a large part of the drainage.
Comment: Several commenters pointed out that although California
red-legged frogs were absent from lower Santa Rosa Creek during the
drought (Rathbun et al. 1991), red-legged frogs have been sighted in
recent years in the lower reaches of the creek, presumably because of
the above average rainfall in the winter of 1992-1993. California red-
legged frogs, which were known to inhabit upper reaches of the creek
during the drought years, were presumed to have traveled downstream to
reoccupy former habitat. One commenter suggested that the Service
should study an entire watershed prior to concluding that the
California red-legged frog is threatened in that watershed.
Service Response: The Service is aware that California red-legged
frogs occur in the upper reaches of Santa Rosa Creek. Santa Rosa Creek
is one of 32 drainages in San Luis Obispo County known to provide
habitat for the California red-legged frog. Neither the Service nor
Rathbun et al. (1991) have concluded that California red-legged frogs
have disappeared from Santa Rosa Creek. Rathbun et al. (1991) refers
only to conditions in the lower portions of the creek and lagoon.
The Service recognizes that the California red-legged frog is
capable of repopulating former habitat when rainfall returns. However,
other factors, including overallocation of water, may exacerbate the
effects of drought through loss of riparian habitat or increased
salinity in coastal lagoons. Where appropriate riparian or wetland
habitat is degraded over the long-term by these hydrologic
modifications, repopulation by California red-legged frogs in altered
portions of the drainage is not possible regardless of whether red-
legged frogs occur in upstream reaches. As portions of the drainage
become unsuitable habitat for California red-legged frogs, isolated
aggregations of frogs become more susceptible to stochastic extinction.
The Service is not basing this listing determination on the status of
the California red-legged frog in any one specific watershed, but
rather on the continuing population decline and threats to the
remainder of its range.
Comment: One commenter noted that California red-legged frogs
persist in upstream portions of Carmel River despite the fact that
bullfrogs are found in the lower river and two reservoirs. The
commenter felt that this evidence refuted the assertion that California
red-legged frog populations usually disappear from a drainage within 5
years after a reservoir is built.
[[Page 25821]]
Service Response: The proposed rule and this final rule state that
California red-legged frogs generally are extirpated from downstream
portions of a drainage 1 to 5 years after filling of a reservoir. Hayes
and Jennings (1988), which is cited as the source of this information,
does not present this cause and effect relationship as an absolute. The
authors state that this relationship depends on the size of the
drainage. In larger drainages, isolated populations can persist
upstream. This final rule has been revised to clarify this point.
Comment: One commenter thought that too much emphasis was given to
the negative impacts of salinity levels in coastal lagoons. Natural
overwash of salt water into coastal lagoons makes these areas
unreliable habitat for California red-legged frogs.
Service Response: The Service acknowledges that coastal lagoons
provide unreliable habitat for California red-legged frogs because of
natural salinity changes caused by wave overwash. However, large
populations of California red-legged frogs do occur in coastal lagoons,
with Pescadero Marsh supporting one of the largest remaining
populations. Therefore, the larger lagoon systems should not be
discounted. Overallocation of stream water resources intensifies the
effect of drought on coastal lagoon populations, which over the long-
term could result in changes in lagoon vegetation and hydrology that
are unfavorable to California red-legged frogs.
Comment: One commenter suggested that competition with tree frogs
and foothill yellow-legged frogs (Rana boylii) may be a contributing
factor in the decline of California red-legged frog.
Service Response: No evidence exists in the literature to support
the theory that competition between California red-legged frogs and
Pacific tree frogs or foothill yellow-legged frogs resulted in
California red-legged frog declines.
Issue 3: Economic and Environmental Effects of Listing
Comment: Several commenters stated that listing of the California
red-legged frog may act to limit or curtail existing uses of private
property, and therefore, a takings implication assessment should be
made prior to taking any final action.
Service Response: Regarding Executive Order 12630, Governmental
Actions and Interference with Constitutionally Protected Property
Rights, the Attorney General has issued guidelines to the Department of
the Interior (Department) on implementation of the Executive Order.
Under these guidelines, a special rule applies when an agency within
the Department is required by law to act without exercising its usual
discretion--that is, to act solely upon specified criteria that leave
the agency no discretion.
In this context, the Service might be subject to legal challenge if
it considered or acted upon economic data. In these cases, the Attorney
General's guidelines state that Takings Implications Assessments (TIAs)
shall be prepared after, rather than before, the agency makes the
decision upon which its discretion is restricted. The purpose of TIAs
in these special circumstances is to inform policy makers of areas
where unavoidable taking exposures exist. Such TIAs shall not be
considered in the making of administrative decisions that must, by law,
be made without regard to their economic impact. In enacting the Act,
Congress required the Department to list species based solely upon
scientific and commercial data indicating whether or not they are in
danger of extinction. The Act does not allow the Service to withhold a
listing based on concerns regarding economic impact. The provisions of
the guidelines relating to nondiscretionary actions clearly are
applicable to the determination of threatened status for the California
red-legged frog.
Comment: Several commenters expressed concern about an adverse
effect of listing the California red-legged frog on the economy.
Another commenter stated that the economic impact of listing the
California red-legged frog would be devastating to an already sluggish
State economy.
Service Response: Under section 4(b)(1)(A) of the Act, a listing
determination must be based solely on the best scientific and
commercial data available. The legislative history of this provision
clearly states the intent of Congress to ``ensure'' that listing
decisions are ``* * * based solely on biological criteria and to
prevent nonbiological considerations from affecting such decisions * *
*'' H. R. Rep. No. 97-835, 97th Cong., 2d Sess. 19 (1982). As further
stated in the legislative history, ``* * * economic considerations have
no relevance to determinations regarding the status of species * * *''
Id. at 20. Because the Service is specifically precluded from
considering economic impacts, either positive or negative, in a final
decision on a proposed listing, the Service need not evaluate or
consider the economic impacts of listing this species.
Comment: One commenter suggested that the researchers who
petitioned the Service to list this species were using the Endangered
Species Act as a method of furthering their personal agenda to remove
livestock from public and private rangeland.
Service Response: The Service is unaware that the researchers who
petitioned the Service to list the California red-legged frog have a
personal agenda to remove livestock from public and private rangeland.
Management of livestock on rangelands is one of many possible
alternatives available to address adverse effects of grazing on
California red-legged frog populations. For example, minor alterations
in management practices and fencing of key riparian areas are two
alternatives that preserve grazing opportunities while protecting
California red-legged frogs.
Comment: Numerous commenters stated that the Service should
consider the human health implications of eliminating the use of
mosquitofish, draining of wetlands, and insecticides to control
mosquitos.
Service Response: California red-legged frogs require still or
slow-moving water with dense emergent and overhanging riparian
vegetation for survival. Sites with these habitat attributes are often
at great distances from urban areas and are not regularly stocked with
mosquitofish or otherwise managed to control mosquitos. Therefore, at
the majority of remaining sites inhabited by California red-legged
frogs, mosquito control is not likely to be an issue. Where mosquitos
are an issue, other biological control methods are available and may be
more appropriate in California red-legged frog habitat. These methods
include application of several species of bacteria (Bacillus sp.), and
more recently, application of a fungus (Lagenidium giganteum), which
apparently attacks and kills only mosquitos. The Service is willing to
work with mosquito and vector control districts to minimize conflicts
between public health and the California red-legged frog.
The Service concludes that listing the California red-legged frog
as a threatened species is not likely to hinder efforts of any Mosquito
and Vector Control Districts to control mosquitos in California.
Comment: One commenter stated that cessation or curtailment of
water releases from reservoirs to accommodate the California red-legged
frog could adversely impact other species, including several species of
anadromous fish.
Service Response: If changes in reservoir release schedules are
needed, the Service, in conjunction with the California Department of
Fish and Game, will consider the needs of all
[[Page 25822]]
species that could be affected as recommendations are made.
Issue 4: Designation of Critical Habitat
Comment: Several commenters recommended that the Service designate
critical habitat for the California red-legged frog so that it would be
easier for interested parties to locate known and additional
populations of the species, and thus, contribute to an accurate
determination of the need for protection. One commenter recommended
designation of critical habitat as an additional way to protect
California red-legged frogs on private land. One commenter stated that
an economic analysis should be conducted prior to designating critical
habitat.
Service Response: The Service has determined that designation of
critical habitat for the California red-legged frog would be more
detrimental than beneficial to the species. Concern for the potential
``take'' of the species (as defined in the Act) through acts of
vandalism has been expressed by the petitioners and other parties (see
further discussion in ``Summary of Factors Affecting the Species''
(Factor B) and ``Critical Habitat'' sections, below). Revealing of the
precise locations of California red-legged frog habitat, as required
through critical habitat designation, would make the species more
vulnerable to vandalism and unauthorized takings. The Service has
determined that designation of critical habitat is not prudent for the
California red-legged frog, therefore, preparation of an economic
analysis is not required. However, the Service has identified recovery
units for the species.
Designation of critical habitat would not necessarily provide
additional protection for California red-legged frog aggregations on
private land. Critical habitat legally applies only to Federal lands or
activities on non-federal lands regulated, sponsored, or funded by a
Federal agency. For example, designation of critical habitat on private
grazing lands would not provide added protection against the impacts of
grazing on California red-legged frog habitat because there is no
federal nexus. Conversely, activities on private lands that are
authorized, funded or carried out by a Federal agency, such as permit
actions authorized under section 404 of the Clean Water Act, would
require consultation with the Service if the activity was expected to
adversely affect a Federally listed endangered or threatened species.
This would apply regardless of whether critical habitat was designated
or not.
Issue 5: National Environmental Policy Act
Comment: Several commenters stated that the proposal to list the
California red-legged frog requires preparation of an Environmental
Impact Statement (EIS) under the National Environmental Policy Act
(NEPA). Another commenter stated that an Environmental Assessment may
be necessary to determine the effects of the listing on other native
species, disease-producing organisms, and humans.
Service Response: The Service need not prepare environmental
assessments or environmental impacts statements pursuant to the
National Environmental Policy Act (NEPA) for reasons outlined in the
Federal Register on October 25, 1983 (48 FR 49244). Basically the
listing of a species is exempt as a matter of law from NEPA review.
Listing decisions are based on biological, not sociological or economic
considerations. This view was upheld in the court case Pacific Legal
Foundation v. Andrus, 657 F. 2d 829 (1981).
Issue 6: Alternate Listing Status Recommended
Comment: Several commenters recommended that the California red-
legged frog be listed as a threatened rather than an endangered species
in various watersheds because measures are already being taken through
Federal, State, and/or private efforts to protect California red-legged
frog habitat, or because the numbers of California red-legged frogs in
these watersheds are greater and the threats less than in other
watersheds within the California red-legged frog's distribution. One
commenter provided examples of specific streams including--(1) Sespe
Creek, where 31 miles within the Forest Service's Sespe Wilderness Area
have been designated as Wild and Scenic, and a portion of Sespe Creek
is included within the Sespe Condor Sanctuary; and (2) Piru Creek,
where flow releases have been modified to protect the Arroyo
southwestern toad (Bufo microscaphus californicus), an endangered
species.
Service Response: Additional information received during the public
comment period regarding new locations of California red-legged frogs
confirmed that the taxon is more widespread within its current range
than previously thought. The existence of 54 new drainage localities,
and some drainages with non-imminent threats, indicates that listing as
a threatened rather than an endangered species is presently more
appropriate for the California red-legged frog. The species is not now
in danger of extinction throughout all or a significant portion of its
range in the near future, however, evidence does indicate that it may
become endangered.
The Service acknowledges that a portion of Sespe Creek is
designated as ``Wild and Scenic'' under the Wild and Scenic River Act,
16 U.S.C. 1271 et seq., and that activities such as reservoir
development or channelization, may be prohibited in this area. The
Service also recognizes that the portion of the creek within the Sespe
Condor Sanctuary may be protected in certain ways. However, designation
as such does not eliminate all potential threats to the California red-
legged frog. For example, designation as Wild and Scenic does not
protect against invasion of bullfrogs or other exotic predators, which
are known to occur in other portions of Sespe Creek. Planned reservoir
development downstream of the Wild and Scenic portion of Sespe Creek
increases the likelihood that bullfrogs and introduced fishes could
disperse into upstream protected portions of the creek. Also, the Wild
and Scenic designation does not eliminate recreational uses of the
creek, including such activities as fishing, camping, mountain biking,
and horseback riding. The Sespe Creek portion of the Sespe Condor
Sanctuary is not closed to recreational use by the public.
On Piru Creek, studies suggest that modified water releases from
Lake Pyramid over the last four years have resulted in increased Arroyo
southwestern toad populations (Cat Brown, Fish and Wildlife Service,
pers. comm., 1994). No research has been conducted to document the
effect of these flow releases on California red-legged frogs.
Although the status of the California red-legged frog is not
uniform throughout its range, the overall picture is one of a
threatened species. Recovery planning and consultations under section 7
of the Act will take into account the status of the California red-
legged frog within recovery units of its range (see ``Available
Conservation Measures'' section).
Comment: One commenter from Santa Barbara County recommended that
the California red-legged frog be listed as a threatened species
because the current range of the California red-legged frog is broad
and includes most of its historic range. Another commenter thought that
the current range of the California red-legged frog, which is 300 miles
north to south, did not fit the definition of an endangered species.
Service Response: Section 3(20) of the Act defines a threatened
species as one which is likely to become an
[[Page 25823]]
endangered species within the foreseeable future throughout all or a
significant portion of its range. Although the current range of the
California red-legged frog encompasses less than 30 percent of its
historic distribution, new information received during the public
comment period suggests that California red-legged frogs are more
widespread within their current range than previously believed. For
this reason and the fact that 17 percent of the remaining drainages
occupied by frogs are not known to be imminently threatened, the
Service has concluded that the California red-legged frog more
appropriately meets the definition of a threatened species.
Comment: Several commenters requested that California red-legged
frogs in specific drainages of the Central Coast or the entire Central
Coast be exempt from endangered species status because California red-
legged frogs seem to be adequately managed in this area, have not shown
population declines, or have fewer exotic species problems.
Service Response: Section 3(16) the Act defines the term
``species'' to include any subspecies of fish, wildlife, or plants, and
any distinct population segment of any species of vertebrate fish or
wildlife that interbreeds when mature. California red-legged frog
aggregations in certain drainages of the central coast of California or
in the entire central coast region do not constitute distinct
vertebrate population segments. The Service cannot exclude these areas
and intends to list the taxon as threatened throughout its range.
Issue 7: Research and Education Needs
Comment: Several commenters recommended the following research
topics be explored in relation to conservation of the California red-
legged frog: (1) Seasonal utilization of patchy habitats for breeding,
refugia and estivation; (2) migration timing; (3) estivation timing;
(4) surveying methodology in marginal habitat; and (5) the effects of
pesticide and herbicide runoff.
Service Response: These comments have been noted and will be
considered during preparation of a recovery plan for the California
red-legged frog.
Comment: One commenter committed to assisting the Service with
cooperative research on mosquitofish/California red-legged frog
interactions.
Service Response: The Service concurs fully with the need for
further research in this area and acknowledges the commenter's
commitment to this effort.
Comment: One commenter asked if a program could be developed that
would allow for variable treatment/management of California red-legged
frog habitat that was found to produce significant numbers of
mosquitoes.
Service Response: Because California red-legged frog habitat is
variable, it is likely that management programs for mosquitoes will
also be variable and depend on the situation under review. Research
into the effects of various methods of mosquito control on California
red-legged frogs should aid the Service in any recovery planning
undertaken for the taxon.
Comment: One commenter recommended a number of ways to educate the
general public regarding listed species and elicit their support,
including publishing information in trade journals, posting signs at
storm drains to discourage dumping of contaminants, reevaluating the
need for channelized creeks, educating the public regarding the effects
of bullfrogs on native amphibians, teaching classes in grade schools,
starting riparian revegetation projects, and encouraging participation
of landowners by providing incentives.
Service Response: The comments have been noted. The Service
welcomes recommendations from the public on how to further the purposes
of the Endangered Species Act. The Service has implemented many of
these recommendations in regard to other listed species and will give
them due consideration in public education programs related to recovery
of the California red-legged frog.
Issue 8: Systematic Relationships Between Red-legged Frog
Subspecies
Comment: Several commenters questioned the Service's exclusion of
the intergrade zone between the northern red-legged frog (Rana aurora
aurora) and the California red-legged frog (Rana aurora draytonii) in
northwestern California. They argued that this segment of the
subspecies' range does not constitute a distinct population segment
and, therefore, cannot be excluded from the listing package. One
commenter suggested that the Service excluded this segment of the
subspecies' range to make the subspecies distribution seem smaller and
in greater need of protection.
Another commenter suggested that the two subspecies are actually
different populations of the same species displaying morphological
differences due to climatic and habitat variations. In this case, the
population numbers and distribution of the species would be much
greater and the need for listing nonexistent.
Service Response: The California red-legged frog is a recognized
subspecies of the red-legged frog (Storer 1925, Cochran 1961, Stebbins
1985). As discussed in the background section of this rule, the range
of the California red-legged frog is 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). Red-legged frogs found in the intergrade zone from
northern Marin County to southern Del Norte County are not considered a
population segment of the California red-legged frog. At this time,
researchers have not assigned the intergrade zone to either subspecies.
Among other differences, red-legged frogs within the intergrade
zone are distinct morphologically from either subspecies of Rana
aurora. The California red-legged frog possesses paired vocal sacs
whereas the northern red-legged frog lacks vocal sacs. Most red-legged
frogs found in the intergrade zone from northern Marin County to
southern Del Norte County possess only one vocal sac. Based on this
pronounced morphological difference in red-legged frogs in the
intergrade zone, some researchers have concluded that the California
and northern red-legged frogs may be two distinct species, and that the
intergrade zone represents a zone of secondary contact or hybridization
between the two species (Hayes and Krempels 1986). Genetic research has
been proposed to clarify systematic relationships (i.e., to determine
if R. a. aurora and R. a. draytonii should be classified as two species
or should remain as subspecies) and allow a more precise identification
of the northern limits of the geographic distribution of the California
red-legged frog (Jennings et al. 1992). In addition, habitat within the
majority of the intergrade zone (moist evergreen/hardwood forest) is
more indicative of habitat preferred by the northern red-legged frog.
Thus, if the Service were to assign the intergrade zone to either
subspecies based on habitat preference alone, the intergrade zone would
be more appropriately placed within the range of the northern red-
legged frog.
Comment: One commenter noted that the California Academy of
Sciences has 66 specimens identified as Rana aurora draytonii that were
collected from Redwood National Park in Humboldt County between 1911
and 1940. The commenter stated that more specific identification of
herpetological subspecies would be needed to
[[Page 25824]]
determine the boundary of California red-legged frogs as far north as
Del Norte County.
Service Response: The specimens referred to by the commenter were
identified as R. a. draytonii in the 1940's based on size, skin
characteristics, and prominence of dorsolateral folds as described by
Camp (1917). More recent research (see Hayes and Miyamoto 1984, Hayes
and Krempels 1986), has identified vocal sac condition as a distinct
morphological characteristic differentiating the two subspecies. Using
these new findings, the researchers who petitioned the Service to list
the species have reviewed the specimens in question and found that they
should have been identified as intergrades between R. a. aurora and R.
a. draytonii. As discussed above, research currently underway is
designed to further refine the northern boundary of the California
subspecies' range.
Comment: Another commenter suggested that the listing package
should only consider red-legged frogs at the species level, and,
therefore, if red-legged frogs were temporarily eliminated from some
part of their range in California, frogs from other areas would
recolonize suitable habitat.
Service Response: Section 3(15) of the Endangered Species Act
defines a species to include ``any subspecies of fish or wildlife or
plants* * *''. Therefore, listing of a recognized subspecies is
authorized in the Act.
The ability of red-legged frogs to migrate from one drainage to
another would be dependent upon the distance, topography and habitat
type through which the frogs would be required to migrate. Considering
the Mediterranean climate in California, with its seasonal dryness, it
is unlikely that red-legged frogs could very successfully migrate long
distances to repopulate formerly occupied habitat.
Issue 9: Existing Regulatory Mechanisms
Comment: Several commenters believed that existing regulations
(i.e., Clean Water Act, California Environmental Quality Act) and
monitoring by several Federal agencies are providing adequate
protection for the California red-legged frog, and, therefore, listing
is not needed.
Service Response: The Service believes that existing regulatory
mechanisms do not currently provide adequate protection for the
California red-legged frog. A discussion of existing regulations can be
found below in Factor D of the ``Summary of Factors Affecting the
Species'' section and the ``Available Conservation Measures'' section.
Issue 10: Miscellaneous
Comment: One commenter pointed out that the Cambria Community
Services District acts responsibly in protecting Santa Rosa and San
Simeon Creek, including reductions in pumping during drought periods,
promoting retrofit programs to reduce water usage, research into
desalination alternatives and reverse osmosis treatment of wastewater,
and approval of riparian habitat improvements.
Service Response: The Service acknowledges the District's efforts
to protect stream flows and the natural environment of Santa Rosa and
San Simeon Creeks. However, the Service has identified threats in these
drainages and other drainages as well.
Comment: One commenter indicated that mosquito abatement districts
have modified their mosquitofish planning protocol to carefully
consider the introduction of mosquitofish in areas inhabited by listed
species.
Service Response: The Service acknowledges the program
modifications made by many mosquito abatement districts to protect
listed species and their habitat.
Summary of Factors Affecting the Species
After a thorough review and consideration of all information
available, the Service has determined that the California red-legged
frog should be listed as a threatened species. Procedures found at
section 4 of the Act (16 U.S.C. 1533 et seq.) and regulations (50 CFR
Part 424) promulgated to implement the listing provisions of the Act
were followed. 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; 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 from herpetologists and data provided by the
researchers who petitioned the Service to list the species indicate
that the California red-legged frog has sustained a reduction of over
70 percent in its historic geographic range in California. Large
aggregations of greater than 350 adults have been documented from only
four areas. These areas included Pescadero Marsh Natural Preserve in
coastal San Mateo County, Point Reyes National Seashore in Marin
County, canals west of San Francisco International Airport in the San
Francisco Bay area (Jennings et al. 1992), and Rancho San Carlos in
Monterey County (Jeff Froke, Rancho San Carlos, in litt., 1994). The
aggregation west of San Francisco International Airport is now thought
to be extirpated (U.S. Fish and Wildlife Service, 1995; David Mullen,
private consultant, pers. comm., 1994).
Habitat loss and alteration are the primary factors that have
negatively affected the California red-legged frog throughout its
range. For example, 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). Wetland
alterations, clearing of vegetation, and water diversions that often
accompany agricultural development make aquatic sites unsuitable for
California red-legged frogs. Urbanization with its associated roadway,
stream channelization, and large reservoir construction projects has
significantly altered or eliminated California red-legged frog habitat,
with the greatest impact occurring in
[[Page 25825]]
southern California. The majority of extant localities are isolated and
fragmented remnants of larger historical populations.
Current and future urbanization poses a significant threat to the
California red-legged frog. Sixty-five drainages (27 percent of the
known occurrences) are associated with urbanization threats (U.S. Fish
and Wildlife Service, 1995). Proposed urban developments 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; the Carmel River in Monterey County; and the Santa
Ynez River in Santa Barbara County. In Santa Cruz County, a proposed
commuter rail project linking Santa Cruz to Watsonville could increase
urban development in southern portions of the county (Patricia O'Keefe,
R.A.I.L.S., in litt., 1994). 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, and Cambria Meadows Creeks and
Estrella and Salinas Rivers could 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 (G. Rathbun and M. Jennings, in litt., 1993).
Loss of habitat and decreases in habitat quality will occur as a
result of on-site degradation of the stream environment and/or riparian
corridor, or through modification of instream flow. Where streams or
wetlands occur in urban areas, the quality of California red-legged
frog habitat is degraded by a variety of factors. Among these factors
are introduction of exotic predators, elimination of streambank
vegetation, collecting, and loss of upland habitat.
Water projects, which accompany urban and agricultural growth, have
had a negative effect on California red-legged frogs and their habitat.
The construction of large 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, have eliminated California red-legged frog habitat or fragmented
remaining aggregations (Jennings et al,. 1992).
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 reproduction (M. Jennings, in
litt., 1993) and maintain populations of exotic predators in downstream
areas that would normally be dry in summer (S. Sweet, in litt., 1993).
Reservoirs are typically stocked with predatory species of fish and
bullfrogs. These species often disperse into surrounding California
red-legged frog habitat disrupting natural community dynamics. Hayes
and Jennings (1988) found that California red-legged frogs generally
were extirpated from downstream portions of a drainage 1 to 5 years
after filling of a reservoir. In some larger drainages, however,
isolated California red-legged frog populations have persisted
upstream. A discussion of exotic predators appears below in Factor C:
``Disease or predation.''
A variety of proposed water projects threaten remaining California
red-legged frog aggregations. 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 drainages represent three of 14 sites remaining
in the Central Valley hydrographic basin with known or potential
localities of California red-legged frogs. On the Salinas River along
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 (Sam Sweet, pers. comm.,
1993).
Water diversions, groundwater well development, and stock pond or
small reservoir construction projects degrade or eliminate habitat.
Diverting water from natural habitats to these projects disrupts the
natural hydrologic regime. During periods of drought, reduced
availability of water within natural drainages combined with drawdown
from the impoundments, disrupts reproduction, foraging, estivation and
dispersal (U.S. Fish and Wildlife Service, 1995) (see Factor E, ``Other
natural or man-made factors affecting its continued existence'' below
for additional discussion of the effects of drought). Proposed or
existing water diversions on the central coast potentially affect the
following drainages: San Simeon, Santa Rosa, Van Gordon, Villa, San
Luis Obispo, Pico, and Little Pico Creeks, Arroyo del Puerta, and
Arroyo Laguna in San Luis Obispo County; the Carmel and Salinas Rivers
in Monterey County; and Canada del Refugio in Santa Barbara County.
Most waterways on the south coast of Santa Barbara County are diverted
to agriculture and other uses, leaving some completely desiccated
(Brian Trautwein, Santa Barbara Urban Creeks Council, in litt., 1994).
Stock ponds and small reservoirs also support populations of exotic
fishes and bullfrogs (G. Rathbun and M. Jennings, in litt., 1993). The
proposed coastal branch of the State Water Project is likely to result
in a number of adverse effects to California red-legged frogs in many
of the 24 areas receiving State water. These effects include, (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 on streams are
current threats 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 which
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 and represent 35 percent of the occupied
drainages in these two counties (U.S. Fish and Wildlife Service 1995).
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.
Management of water bodies for flood control also has the potential
to adversely impact California red-legged
[[Page 25826]]
frog localities. In San Mateo County, poorly timed releases of storm
water from Horse Stable Pond at Sharp Park in February 1992, resulted
in exposure and desiccation of 62 California red-legged frog egg masses
(Todd Steiner, Earth Island Institute, in litt., 1994). Channel
maintenance at San Francisco International Airport may have contributed
to extirpation of one of the four largest remaining aggregations of the
California red-legged frog.
Routine road maintenance, trail development, and facilities
construction activities associated with parks 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. Construction activities in
or adjacent to streams at Butano and Portola State Parks in San Mateo
County; Big Basin, Wilder Ranch, and Henry Cowell State Parks in Santa
Cruz County; and Mt. Diablo State Park in Contra Costa County have the
potential to adversely affect California red-legged frogs inhabiting
downstream reaches (Coyote Creek Riparian Station, in litt., 1993).
Placer mining may threaten California red-legged frog habitat.
Jennings (pers. comm., 1994) observed heavy siltation in late spring
and summer in portions of Piru Creek known to support California red-
legged frogs. The siltation resulted from upstream gold mining. Deep
holes in streams created by instream placer mining also may provide
habitat for exotic predatory fish (Jennings, pers. comm., 1994).
Creeks, streams and rivers are open to suction dredging throughout the
year in 13 of 22 counties within the current range of the California
red-legged frog (State of California 1994).
Road-killed California red-legged frogs have been documented at
several locations in San Mateo and Santa Cruz Counties (Coyote Creek
Riparian Station, in litt., 1993; Mike Westphal, Coyote Creek Riparian
Station, in litt., 1995). Road kills may deplete frog aggregations in
borderline habitat and otherwise protected areas. Where roads cross or
lie adjacent to California red-legged frog habitat, they may act as
barriers to seasonal movement and dispersal.
Livestock grazing is another form of habitat alteration that is
contributing to declines in the California red-legged frog. Numerous
studies, summarized in Behnke and Raleigh (1978) and Kauffman and
Krueger (1984), have shown that livestock grazing negatively affects
riparian habitat. Cattle have an 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. 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 (Hayes and Jennings 1988, Jennings 1988b). Cattle grazing also
results in increased erosion in the watershed (Lusby 1970, Winegar
1977), which accelerates the sedimentation of deep pools (Gunderson
1968) used by California red-legged frogs and adversely affects aquatic
invertebrates (Cordone and Kelley 1961). Aquatic invertebrates are
common prey items of California red-legged frogs.
Behnke and Zarn (1976) identified livestock grazing as the greatest
threat to the integrity of stream habitat in the western United States.
Numerous symposia and publications have documented the detrimental
effects of livestock grazing on streams and riparian habitats (Johnson
and Jones 1977; Meehan and Platts 1978; Behnke and Raleigh 1979; Bowers
et al. 1979; Cope 1979; Platts 1981; Ohmart and Anderson 1982 and 1986;
Peek and Dalke 1982; Kauffman et al. 1983; Menke 1983; Kauffman and
Krueger 1984; Johnson et al. 1985; GAO 1988; Clary and Webster 1989;
Gresswell et al. 1989; Kinch 1989; Minshall et al. 1989; Chaney et al.
1990 and 1993). These effects include nutrient loading, reduction of
shade and cover with resultant increases in water temperature,
increased intermittent flows, changes in stream channel morphology, and
the addition of sediment due to bank degradation and off-site soil
erosion. Indirect effects of increased water temperatures can be lethal
to aquatic species and include: creating a more favorable environment
for introduced species, changing the food chain, degrading water
quality through decreased dissolved oxygen, increased production of
algae, and increased pH and ammonia.
Various studies have shown that water temperatures have been
reduced when streambank vegetative cover is protected from grazing.
Storch (1979) found that daily fluctuations of water temperatures in
late August and early September averaged 27 deg. F outside an exclosure
on Camp Creek, Oregon that was ungrazed for 10 years, compared to
13 deg. F inside the exclosure. Also, maximum water temperatures
outside the exclosure averaged 11 deg. F higher than inside the
exclosure. Van Velson (1979) reported that average water temperatures
in Otter Creek, Nebraska, decreased 3 deg. F after livestock were
excluded for 1 year.
Grazing effects are not limited to riparian areas. Improper grazing
of upland vegetation can expose soils to erosive impacts of rain drops,
reduce water infiltration, and accelerate runoff. This can erode
topsoil and cut rills and gullies, concentrating runoff, deepening
gullies, lowering water tables, and increasing sediment production
(Chaney et al. 1993). Sediment introduced into streams can alter
primary productivity and food supply, fill interstitial spaces in
stream bed material, impeding water flow, reducing dissolved oxygen
levels, and restricting waste removal (Chapman 1988). Suspended
sediments reduce light penetration to plants and reduce oxygen carrying
capacity of the water (Ohmart and Anderson 1982). Reduction in
photosynthesis and primary production decreases productivity of the
entire ecosystem (Minshall et al. 1989).
Livestock grazing can cause a nutrient loading problem (due to
urination and defecation) in areas where cattle are concentrated near
the water (Doran et al. 1981), but in other areas it can reduce
nutrients through removal of riparian vegetation (Fisher 1972).
Riparian vegetation provides organic material for approximately 50
percent of a stream's nutrient energy (Cummins 1974). Detritus from
such plants is a principal source of food for aquatic invertebrates
(Minshall 1967; Meehan et al. 1977). Streamside vegetation also
provides habitat for terrestrial insects, another important dietary
component for other aquatic or riparian associated species.
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 of the 14 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
[[Page 25827]]
sedimentation of aquatic habitats either directly or indirectly caused
by livestock grazing and off-road vehicle use (Jennings et al. 1992).
Galen Rathbun (National Biological Service, 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. Grazing practices can,
however, be modified to minimize impacts to California red-legged
frogs. Five-fold increases in California red-legged frog populations on
Rancho San Carlos in Monterey County may be attributable in part to
modifications of grazing programs (J. Froke, in litt., 1994).
In addition to cattle, feral pigs (Sus scrofa) also disturb the
riparian zone through their rooting, wallowing and foraging behavior in
the shallow margins of water bodies. Feral pigs disturb and destroy
vegetative cover, trample plants and seedlings, and cause erosion. At
Pinnacles National Monument, soil compaction and possible disturbance
of frog eggs caused by feral pigs have been noted in California red-
legged frog habitat (Stanley Albright, National Park Service, in litt.,
1994).
Off-road vehicle use adversely affects California red-legged frogs
in ways similar to livestock grazing and feral pig disturbance. Off-
road vehicles damage riparian vegetation, increase siltation in pools,
disturb the water in stream channels and crush eggs, larvae, juveniles,
and adults. California red-legged frogs were eliminated in part by off-
road vehicle activities at the Mojave River above Hesperia, at Rincon
Station on the west fork of the San Gabriel River, and in Piru Creek
above Pyramid Lake (M. Jennings, pers. comm., 1993).
Heavy recreational use of parks (e.g., fishing, hiking, exploring)
also can degrade habitat for the California red-legged frog. At Big
Basin Redwood Park in Santa Cruz County, heavy recreational use may
have contributed to the disappearance of California red-legged frogs
from Opal Creek (Coyote Creek Riparian Station, in litt., 1993).
Timber harvest threatens California red-legged frogs through loss
of riparian vegetation 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), Whitehouse Creek (U.S. Fish
and Wildlife Service 1995) and occurs periodically on a tributary of
Blooms Creek (Coyote Creek Riparian Station, in litt., 1993). The
proposed timber harvests would occur in three of 18 streams in the
County that support California red-legged frogs. In Pescadero Creek at
Portola State Park (San Mateo County), erosion and siltation caused by
severe winter storms and upstream logging operations may have been the
cause of the disappearance of California red-legged frogs from this
portion of the stream (Coyote Creek Riparian Station, in litt., 1993).
B. Overutilization for commercial, recreational, scientific, or
educational purposes. Records of harvesting California red-legged frogs
for human consumption date back to an account by Lockington (1879) of
the commercial harvest of this species for San Francisco fish markets.
From 1890 to 1900, the California red-legged frog supported a
significant commercial harvest (Smith 1895) of about 80,000 frogs
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). Continued
harvesting of California red-legged frogs for food by local individuals
has been reported for the Central Coast region (Coyote Creek Riparian
Station, in litt., 1993). California red-legged frogs reportedly taste
better than bullfrogs, a statement first made by Dickerson (1906).
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 available commercially from suppliers
located outside California in the pet trade. Because the State of
California prohibits possession of wild California red-legged frogs
without a permit, frogs sold in the pet trade presumably are reared in
captivity (M. Jennings, pers. comm., 1993).
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 spp.) (Fitch 1940, Fox 1952), including the endangered San
Francisco garter snake (Thamnophis sirtalis tetrataenia) (Barry 1978,
Wharton et al. 1986). Recent postmetamorphs also may be particularly
vulnerable to predation by garter snakes, as was found in other species
of ranid frogs by Arnold and Wassersug (1978). Raccoons (Procyon
lotor), which are abundant in urban settings, were the likely predator
of eight radio-tagged California red-legged frogs in the riparian
corridor of Pico and San Simeon Creeks in San Luis Obispo County
(Rathbun, in litt., 1994). Other possible, but undocumented mammalian
predators include striped skunks (Mephitis mephitis), spotted skunks
(Spilogale putorius), and red fox (Vulpes fulva). Larvae may be preyed
upon by aquatic beetles and damsel fly naiads (Karl Malamud-Roam,
Contra Costa County Mosquito and Vector Control District, in litt.,
1994).
Introduced predators of particular concern are the bullfrog, red
swamp crayfish (Procambarus clarkii), signal crayfish (Pacifastacus
leniusculus), and several species of fish, including bass, catfish
(Ictalurus spp.), sunfish, and mosquitofish (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). Joseph DiDonato
(East Bay Regional Park District, pers. comm., 1994) has observed the
disappearance of California red-legged frogs from Pleasanton Ridge in
Alameda County within the last ten years. Today, all former California
red-legged frog habitat on Pleasanton Ridge is occupied by bullfrogs.
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
[[Page 25828]]
competition. All sites in the Sierra Nevada foothills that supported
California red-legged frogs in the 1970s now are inhabited by bullfrogs
(M. Jennings, in litt., 1993). Over the last decade, Jennings (in
litt., 1993) has observed bullfrogs moving upstream and/or downstream
into formerly pristine 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. Bullfrogs are
introduced into drainages by stocking of reservoirs and stock ponds,
dispersal and colonization, conveyance of project water from other
streams inhabited by these exotics, and releases by individuals. At The
Nature Conservancy's Santa Rosa Plateau Reserve in Riverside County
(the only site south of the Santa Clara River drainage 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). Additional bullfrogs were removed
from the preserve in 1989 after apparent introductions from a nearby
frog jumping contest (M. Jennings, in litt., 1994). Once established,
it is extremely difficult 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). Over 60 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 (U.S. Fish and
Wildlife Service 1995). Based on documented rates of local extinction,
the Service concludes that eventually California red-legged frogs will
be locally extirpated from these 149 streams.
Bullfrogs prey on California red-legged frogs (S. Sweet, in litt.,
1993), other ranid frogs (Twedt 1993) and other amphibians and aquatic
reptiles (Schwalbe and Rosen 1988). Twedt (1993) documented four
juvenile northern red-legged frogs among the contents 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 80 mm (3.1 in.)) and adult female
(approximately 85 mm (3.3 in.)) red-legged frog, indicating that
bullfrogs could prey on subadult red-legged frogs. Stuart and Painter
(1993) found evidence of cannibalistic behavior in bullfrogs. A stomach
content analysis revealed 87 percent of total volume by weight was
composed of newly-metamorphosed and larval Rana. Bullfrogs may have a
competitive advantage over California 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 up to 20,000 eggs during a breeding season (Emlen
1977), and (4) larvae being unpalatable to predatory fish (Kruse and
Francis 1977). Bullfrogs also interfere with red-legged frog
reproduction. Several researchers have noted male red-legged frogs in
amplexus with (mounted on) both male and female 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 1988b; Jennings, pers. comm., 1993).
Hayes and Jennings (1986, 1988) found a negative correlation
between the abundance of introduced fish species and California red-
legged frogs. These authors noted that 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 California red-legged frogs in the Salinas
River drainage, by DiDonato (in litt., 1994) on East Bay Regional Park
District properties in the San Francisco Bay area, by Shaffer (in
litt., 1994) for the inner coast range, and by Moyle (1973) for the
foothill yellow-legged frog. These references suggest that the observed
negative correlation between California red-legged frogs and non-native
fish is a general principal. Of 32 streams examined by Hayes and
Jennings (1988), introduced fishes were found in 44 percent.
Results of a recent study in artificial ponds showed that
mosquitofish and bluegill (Lepomis macrochirus) were significant
predators of California red-legged frog larvae (Schmieder and Nauman
1994). However, California red-legged frogs have been found in
association with mosquitofish in Corral Hollow Creek (Alameda and San
Joaquin counties) (T. Strange, pers. comm., 1994) and in three
waterbodies on East Bay Regional Park properties in Contra Costa County
(K. Swaim, in litt., 1994). Malamud-Roam (in litt, 1994) reported that
mosquitofish occur in at least four streams in Contra Costa County
known to support California red-legged frogs. Mosquitofish also may
compete with California red-legged frogs by consuming aquatic insects
that are potential food sources for postmetamorphic frogs. Mosquitofish
have become established statewide and are stocked routinely by mosquito
abatement districts as a mosquito control measure (Moyle 1976).
D. The inadequacy of existing regulatory mechanisms. Although the
California red-legged frog is classified as a ``Species of Special
Concern'' by the State of California (Steinhart 1990) and may not be
taken without an approved scientific collecting permit, this
designation provides no special, legally mandated protection of the
species and its habitat. 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).
However, because of the rarity of the California red-legged frog and
similarity to the more common bullfrog, protection of this taxon by
State wardens and rangers may be compromised (Coyote Creek Riparian
Station, in litt., 1993).
Section 1603 of the California Fish and Game Code authorizes the
Department of Fish and Game (CDFG) to regulate streambed alteration.
The Department must be notified and approve any work that substantially
diverts, alters, or obstructs the natural flow or substantially changes
the bed, channel or banks of any river, stream, or lake. If an existing
fish or wildlife resource may be substantially adversely affected by a
project, CDFG must submit proposals to protect the species within 30
days. However, if the Department does not respond within 30 days of
notification, the applicant may proceed with the work.
Section 404 of the Clean Water Act is the primary Federal law that
potentially provides 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 five cubic feet per second (cfs) mean
annual flow) or for isolated waters, unless a listed species may be
adversely affected. Many aggregations of
[[Page 25829]]
California red-legged frogs occur in isolated wetlands and coastal
streams that may have mean annual flows less than five 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, when the California red-
legged frog is listed, the Corps will 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 affecting California red-legged
frog habitat.
Additionally and equally important, the upland habitats adjacent to
riparian zones are not provided any protection by Section 404 of the
Clean Water Act. Upland areas provide estivation and dispersal habitats
for this species.
Federal lands, including those of the Forest Service, National Park
Service, Bureau of Land Management, Bureau of Reclamation, 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. State, County, and
Regional Park lands provide some protection from some threats, however,
these parks are managed for multiple uses.
The National Environmental Policy Act (NEPA) and California
Environmental Quality Act (CEQA) require an intensive environmental
review of projects that may adversely affect a Federally listed
species. However, project proponents are not required to avoid impacts
to non-listed species, and proposed mitigation measures are frequently
not adequately implemented. As with section 404 permits, the Service's
comments through these environmental review processes are only
advisory. The Service is aware of a proposed recreational development
in Santa Cruz County undergoing environmental review that is expected
to extirpate an estimated 10 percent of the total remaining numbers of
the California red-legged frog (Westphal in litt. 1995).
The California Coastal Act regulates the approval of developments
within the costal zone. Although a significant slowing in wetland
losses has occurred, the continued loss and degradation of coastal
wetlands since the California Coastal Act was enacted in 1974 attests
to the limitations of this legislation.
E. Other natural or man-made factors affecting its continued
existence. Six consecutive years of drought (1986-1992) in California
severely affected remaining California red-legged frogs in the Sierran
foothills. Many sites in intermittent streams that held California red-
legged frogs before the drought were completely dry during field
surveys conducted between 1985 to 1992 (Jennings et al. 1992). 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). Long-term survival of California
red-legged frogs may be compromised by the elimination of refuge areas
during times of the year when the stream is dry (Rathbun, in litt.,
1994). However, California red-legged frog populations are undoubtedly
capable of recovering from drought, provided other factors have not
irreparably degraded their habitat, or California red-legged frogs have
not been completely extirpated from the drainage.
Drought also may play a role in decreased California red-legged
frog reproduction where frogs occur in coastal lagoons. High salinities
in the Pescadero Marsh (San Mateo County) have been attributed to
drought conditions in the watershed. At the Pescadero Marsh Natural
Preserve, Jennings and Hayes (1990) found many dead egg masses in a
portion of the marsh that were killed by excessive (>4.5 parts per
thousand) salinity levels. Rathbun et al. (1991) speculated that the
absence of California red-legged frogs in lower Santa Rosa Creek and
lagoon in San Luis Obispo County was due to long-term drought
exacerbated by instream flow withdrawals. Since the end of the drought
California red-legged frog numbers reportedly have increased in lower
Santa Rosa Creek (Rathbun in litt. 1994; G. Schmitt, United Residential
Lot Owners of Cambria, Inc. in litt. 1994) probably as a result of
increased rainfall in the winter of 1992-1993. 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).
Increased salinity could also result from periodic overtopping of the
beach bar during high tides or by storm waves (D. Asquith, private
consultant, in litt. 1994). In 1993, Jennings (pers. comm., 1993)
reported the loss of California red-legged frog egg masses from
increased salinity and unusual flooding 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.
The overall effect of contaminants on California red-legged frogs
has not been studied. Only one incident of California red-legged frog
mortality is known from a diesel and gasoline spill in a tributary of
Blooms Creek (Santa Cruz County) (Coyote Creek Riparian Station, in
litt., 1993).
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 and their habitat (S. Sweet, pers.
comm., 1993).
Extensive flooding has been cited by Jennings and Hayes (1994a) 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 1994a). The disappearance of this species from the drainage
coincided with a catastrophic flood event in the Mojave River in the
winters of 1968 and 1969. Extensive flooding in other portions of the
California red-legged frog range may have combined with other factors
to eliminate California red-legged frog aggregations (Richard Seymour,
Coyote Creek Riparian Station, in litt., 1993; D. Martin, pers. comm.,
1994).
A considerable amount of occupied California red-legged habitat
exists in the form of isolated patches along stream courses. These
patches of suitable habitat represent mere remnants of a much larger
historical habitat that once covered whole drainages. Fragments of
formerly extensive populations of California red-legged frogs are now
isolated from other populations. Populations isolated in habitat
fragments are vulnerable to extinction through random environmental
events or anthropogenic catastrophes. With only three of 243 known
creeks or drainages supporting populations of over 350 adults, all
remaining occurrences are considered vulnerable to these threats. Once
a local
[[Page 25830]]
extinction event occurs in an isolated habitat fragment, the
opportunity for recolonization from a source population is reduced.
Thus, local extinctions via stochastic processes, coupled with habitat
fragmentation may represent a substantial threat to the continued
existence of the California red-legged frog over much of its range.
The Service has carefully assessed the best scientific and
commercial data available regarding the past, present, and future
threats faced by the California red-legged frog in determining to make
this final decision. Based on this evaluation, the preferred action is
to list the California red-legged frog (Rana aurora draytonii) as
threatened. This taxon has been extirpated from 70 percent of its
former range. Although California red-legged frogs are now known to be
found in more locations within their present range than previously
thought, factors adversely affecting the California red-legged frog are
known to exist in 83 percent of the drainages supporting the taxon
(U.S. Fish and Wildlife Service 1995). These factors include but are
not limited to (1) urban encroachment, (2) construction of large and
small reservoirs, water diversions and well development, (3) flood
control maintenance, (4) road maintenance, (5) placer mining, (6)
livestock grazing and feral pigs, (7) off-road vehicle use, and (8)
introduction or presence of exotic predators and competitors. The
remaining 17 percent of occupied drainages, the majority located in
Monterey, Santa Barbara, and San Luis Obispo counties, currently are
not known to be subject to the above threats. The California red-legged
frog, therefore, more appropriately fits the definition of a threatened
species. For the reasons discussed below, critical habitat has not been
proposed.
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
a species is determined to be endangered or threatened. The Service
finds that designation of critical habitat is not prudent for the
California red-legged frog at this time. 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.
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. comm., 1993; D. Martin, pers. comm., 1994).
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 acts of vandalism, and increase the
difficulties of enforcement. Martin (pers. comm., 1994) has observed
acts of vandalism by private landowners once they learned of the
presence of Yosemite toads (Bufo canorus), on their property. The
Yosemite toad is a species of concern to the Service (former category 2
species, 59 FR 58995).
In addition, a significant market exists in California for frog
meat, with bullfrogs as the primary species sold. In 1993, the
California Department of Fish and Game arrested a number of individuals
involved in illegal collection and sale of large numbers of bullfrogs
to San Francisco fish markets (California Department of Fish and Game
1993). To the untrained eye, the California red-legged frog looks very
similar to a bullfrog and could be accidentally taken for the market.
California red-legged frogs also could be taken intentionally as they
are reported to be more palatable (Coyote Creek Riparian Station, in
litt., 1993; Jennings, pers. comm., 1994). The California red-legged
frog would be more vulnerable to collection for market consumption if
precise locality data were published for this species. Protection of
California red-legged frog habitat will be addressed in the recovery
process and through the section 7 consultation process. Therefore, due
to the serious potential for increased, unauthorized take, the Service
has determined that designation of critical habitat for the California
red-legged frog is not prudent.
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 practices. 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, as amended, requires Federal agencies to
evaluate their actions with respect to any species that is proposed or
listed as endangered or threatened and with respect to its critical
habitat, if any is being designated. Regulations implementing this
interagency cooperation provision of the Act are codified at 50 CFR
part 402. Section 7(a)(4) of the Act requires Federal agencies to
confer with 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 subsequently, section 7(a)(2) requires Federal
agencies to ensure that activities they authorize, fund, or carry out
are not likely to jeopardize the continued existence of the species or
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 final
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 status surveys for California red-legged frogs
(Daphne A. Hatch, National Park Service, in litt., 1993; James
Sleznick, National Park Service, in litt., 1992;
[[Page 25831]]
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;
Maeton Freel, U.S. Forest Service, pers. comm., 1994). In Los Padres
National Forest, the Forest Service, in a cooperative effort with other
Federal and State agencies, has altered flow regimes in Piru Creek
between Lake Pyramid Lake and Lake Piru to benefit the endangered
arroyo southwestern toad. Although no specific studies have been done,
these flow regime changes also may benefit the California red-legged
frog (Frederick Gientke, United Water Conservation District, in litt.,
1994). The Forest Service has also designated more than 31 miles of
Sespe Creek in Los Padres National Forest as ``Wild and Scenic'' under
the National Wild and Scenic Rivers Act of 1968.
The Contra Costa Water District is constructing a large reservoir
construction project (Los Vaqueros Reservoir) on Kellogg Creek, Contra
Costa County (Contra Costa Water District 1993). The Bureau of
Reclamation's role in this project is to amend water service contracts
and modify water rights to facilitate project construction (Penny
Howard, U.S. Bureau of Reclamation, in litt., 1994). A mitigation and
monitoring program is proposed to compensate for California red-legged
frog habitat losses at Los Vaqueros. 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. In addition,
Bureau of Reclamation projects, including small loan projects in
Monterey County, the Cachuma project in Santa Barbara County, the San
Felipe project in San Benito and Santa Clara counties, and the Solano
project in Solano County, involve water contract renewals as well as
road maintenance activities and grazing leases, all of which may affect
California red-legged frogs. The U.S. Army Corps of Engineers would be
involved in many of these projects 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 may affect the California red-legged frog. To the extent that their
habitats overlap in lagoon areas, efforts made to conserve and recover
the tidewater goby (Eucyclogobius newberryi), a Federally listed
endangered species, may also help to conserve and recover the
California red-legged frog.
The Service is currently involved in the development of two Habitat
Conservation Plans (HCP's) that could potentially protect three
localities of California red-legged frogs. The Kern County Valley Floor
HCP will protect a minimum of 75 percent of the existing California
red-legged frog habitat in the Bitterwater Creek drainage. The San
Joaquin County multispecies HCP may also protect two localities, Corral
Hollow Creek and Lone Tree Creek. Although the development of these
HCP's will not preclude the need to list the California red-legged
frog, these plans, if implemented, will protect habitat for the taxon.
The Ventura Field Office is assisting with the Santa Clara River
Enhancement and Management Plan, which is progressing but is not
finalized at this time. A similar plan for Rancho San Carlos (in the
Carmel River drainage) is also underway. Early planning efforts are
beginning for the Ventura and Santa Ynez rivers. None of these planning
efforts preclude the need to list the species, but will provide future
protection of habitat for the species.
One known California red-legged frog locality in Riverside County
and any newly discovered localities in the historic range of the
species could be protected by ongoing ecosystem-based planning efforts
in southern California. In 1991, the State of California established
the Natural Communities Conservation Planning (NCCP) Program to address
conservation needs of natural ecosystems throughout the State. The
initial focus of the program is the coastal sage scrub community in
southern California, however, riparian habitats will also be addressed.
Several regional plans, including the Multi-species Conservation Plan
(MSCP) and the Multi-habitat Conservation Plan (MHCP) of San Diego
County, the Southern and Central Coastal Subregional NCCP/Habitat
Conservation Plans (Southern/Central/Coastal NCCP) of Orange County,
and the Riverside County Stephens Kangaroo rat HCP and San Bernardino
County MSCP are under development by a consortium of county and
municipal governments and other parties, including the California
Department of Fish and Game and the Service. Though no plans have been
completed to date, protection could be provided if the California red-
legged frog occurs in any of the planning areas. The one known extant
population occurs on the Santa Rosa Plateau Reserve managed by The
Nature Conservancy.
The Service establishes the following recovery units within the
historical range of the California red-legged frog: (1) The western
foothills and Sierran foothills to 5,000 feet in elevation in the
Central Valley Hydrographic Basin; (2) the central coast ranges from
San Mateo and Santa Clara counties south to Ventura and Los Angeles
counties; (3) the San Francisco Bay/Suisun Bay hydrologic basin; (4)
southern California, south of the Tehachapi Mountains; and (5) the
northern coast range in Marin and Sonoma counties. These five units are
essential to the survival and recovery of the California red-legged
frog. Designation of recovery units assists the Service and other
agencies in identifying priority areas for conservation planning under
the consultation (section 7) and recovery (section 4) programs.
The Act and implementing regulations found at 50 CFR 17.32 set
forth a series of general prohibitions and exceptions that apply to all
threatened wildlife not covered by a special rule. 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 threatened wildlife species under certain circumstances.
Regulations governing permits are at 50 CFR 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.
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 species' range.
The Service believes that, based on the best available information, the
following
[[Page 25832]]
actions will not result in a violation of section 9:
(1) Road-kills or injuries caused by vehicles operated lawfully on
designated public roads;
(2) Light to moderate carefully managed livestock grazing that
prevents or minimizes the excessive trampling of riparian and wetland
habitat;
(3) Possession of legally acquired California red-legged frogs;
(4) Unintentional hooking of a frog or tadpole during otherwise
lawful engagement in fishing, and;
(5) Federally approved projects that involve activities such as,
discharge of fill material, draining, ditching, tiling, pond
construction stream channelization or diversion, or alteration of
surface or ground water into or out of a wetland (i.e., due to roads,
impoundments, discharge pipes, storm water detention basins, etc.),
when such activity is 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
California red-legged frog and result in ``take'', include, but are not
limited to:
(1) Unauthorized collecting or handling of the species;
(2) Introduction of exotic species such as fish or other species of
frogs directly into, or within dispersal distance of, known California
red-legged frog habitat;
(3) Unauthorized destruction/alteration of the species' habitat
such as discharge of fill material, draining, ditching, tiling, pond
construction, diversion or alteration of stream channels or surface or
ground water flow into or out of a wetland (i.e., due to roads,
impoundments, discharge pipes, storm water detention basins, etc.),
operation of any vehicles within the stream channel;
(4) Violation of discharge permits;
(5) Burning, cutting or mowing of wetland or riparian vegetation,
if conducted in an untimely or inappropriate manner (e.g., when
California red-legged frogs would be killed or injured, or their
occupied habitat would be degraded or rendered unsuitable);
(6) Pesticide applications in violation of label restrictions;
(7) Discharges or dumping of toxic chemicals, silt, or other
pollutants (i.e., sewage, oil and gasoline) into waters, or riparian
and upland habitats supporting the species;
(8) 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 plants and general
inquiries regarding prohibitions and permits may be addressed to the
U.S. Fish and Wildlife Service, Ecological Services, Endangered Species
Permits, 911 N.E. 11th Avenue, Portland, Oregon, 97232-4181 (telephone
503/231-2063; facsimile 503/231-6243).
National Environmental Policy Act
The Fish and Wildlife Service has determined that Environmental
Assessments and Environmental Impact Statements, as defined under the
authority of the National Environmental Policy Act of 1969, need not be
prepared in connection with regulations adopted pursuant to section
4(a) of the Endangered Species Act of 1973, as amended. A notice
outlining the Service's reasons for this determination was published in
the Federal Register on October 25, 1983 (48 FR 49244).
References Cited
A complete list of all references cited herein is available upon
request from the Field Supervisor, Sacramento Field Office (see
ADDRESSES section).
Author
The primary authors of this final rule are Karen J. Miller, Alison
Willy, Sheila Larsen, and Steven Morey, 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, and 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 rules
Common name Scientific name threatened habitat
--------------------------------------------------------------------------------------------------------------------------------------------------------
AMPHIBIANS
* * * * * * *
Frog, California red-legged.... Rana aurora U.S.A. (CA)....... Entire (excluding Del T ........... NA NA
draytonii. Norte, Humboldt,
Trinity, & Mendocino
Cos., CA; Glenn, Lake,
& Sonoma Cos., CA,
west of the Central
Valley Hydrologic
Basin; Sonoma & Marin
Cos., CA, west & north
of San Francisco Bay
drainages and Walker
Creek drainage; and
NV).
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 25833]]
Dated: May 17, 1996
Mollie H. Beattie,
Director, Fish and Wildlife Service.
[FR Doc. 96-12901 Filed 5-22-96; 8:45 am]
BILLING CODE 4310-55-P
This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.