FERC Project No. 2079 - PCWA Middle Fork American River Project ...

Application for New License Middle Fork American River Project (FERC Project No. 2079)
activity pattern similar to that of adults. During daYosemite toadime, tadpoles associate
with the shallow margins of small pools (presumably where water temperature is
warmer), but retreat to deeper water at night and remain quiescent on the benthos
(Mullally 1953). Metamorphosis generally occurs in early fall, but some tadpoles at
higher elevations probably overwinter (Mullally 1956).
There are no occurrences of Yosemite toad in the MFP. As stated previously, the
current geographic range for Yosemite toad extends generally from Inyo to Mono
counties within the Sierra Nevada (USFWS 2010), from approximately 6,400 to
11,300 feet msl. The nearest known populations are along southeast corner of the
where it borders the Stanislaus National Forest (USFWS 2009), approximately 43 miles
south of the MFP. Because the MFP is north of its known range, the Yosemite toad is
unlikely to occur within Project boundaries.
Mating and egg laying occurs from March to July. Habitat association and activity
patterns of tadpoles in lakes and streams have not been investigated. Tadpoles
overwinter for two to three years at high elevation sites before metamorphosis is
complete (Wright and Wright 1949). In summary, relatively little information is known
about the habitat associations of the different life history stages of this high elevation
species.
FOOTHILL YELLOW-LEGGED FROG (RANA BOYLII; FSS, CSC)
The foothill yellow-legged frog (FYLF) is a stream-dwelling frog native to California and
Oregon (Storer 1925, 1955). As a stream obligate species, adult and juvenile FYLF
primarily associate with pool and riffle habitats with gently to moderately flowing water.
Tadpoles are often found in shallow near-shore habitats such as eddies, backwaters,
and other low velocity areas. In eastern California it ranges from the Sierra Nevada
foothills to approximately 4,500 feet. Few studies have investigated the natural history
of the FYLF. Jennings and Hayes (1985) quantified the habitat associations of this
species in the Sierra Nevada. In a survey of 29 streams in the Sierra Nevada, the FYLF
was found to be primarily associated with similar habitat, substrate, and canopy as
reported for populations in streams and rivers of the Coast Range. However, they are
also found in other stream habitats ranging from small, rocky, high gradient streams no
more than 1.5 feet wide, to areas where small tributaries connect with large rivers in the
Sierra Nevada (Van Wagner 1996).
The FYLF generally associates with low gradient streams with moderate streamflow
over coarse substrates. In the Sierra Nevada, individuals have also been observed in
steep gradient reaches in habitats such as cascades and bedrock waterfalls. Although
such habitats are not optimal for breeding, they may be used in spring while adults
migrate downstream to reach breeding habitat near the confluence with larger streams.
Coarse material such as cobbles, boulders, and large woody debris provide suitable
sites for oviposition. Larger substrates typically remain stable in spring when streamflow
is high as the winter snowpack melts. During the summer foraging season when
flows are low, coarse material protruding above the channel bed provides optimal sites
for basking and feeding. Although individuals have been found associated with finer
February 2011 B-10