Sequoia Slender Salamander
© 2018 William Flaxington (1 of 8)
Batrachoseps kawia Jockusch, Wake and Yanev, 1998
Robert W. Hansen1
1. Historical versus Current Distribution. The known distribution of Sequoia slender salamanders (Batrachoseps kawia) lies entirely within the Kaweah River drainage (Tulare County) on the western slope of the Sierra Nevada of California, at elevations of 430–2,205 m (Jockusch et al., 1998). The six known sites are located within the South, East, and Middle Fork Kaweah River drainages; additional fieldwork will likely reveal populations of Sequoia slender salamanders along the North and Marble Forks as well. Most of these populations were discovered many years ago but were regarded at the time as belonging to more wide-ranging species (see "Comments" below).
2. Historical versus Current Abundance. There is little information concerning the status of Sequoia slender salamanders populations, although all known localities appear to have undergone little change in recent decades. The two high-elevation sites near Silver City (East Fork Kaweah River drainage), first discovered in 1982, were revisited 18 yr later, but salamanders were not found (R.W.H., unpublished data).
3. Life History Features.
A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. Unknown. For the lower elevation populations, courtship presumably occurs after the start of the rainy season in the fall (November–December), and egg-laying probably takes place from December–January, depending on local rainfall. The high elevation sites lie above 2,000 m and experience heavy snowfall during the winter and below freezing temperatures well into spring. Presumably, breeding activity commences in May–June, but this remains to be established.
ii. Breeding habitat. Nest sites have not been found.
i. Egg deposition sites. Unknown.
ii. Clutch size. Unknown.
C. Direct Development. Hatchlings have not been observed, but should be expected to appear in late winter to early spring at low elevation sites, and perhaps in mid to late summer at higher elevations.
D. Juvenile Habitat. Unknown.
E. Adult Habitat. Over their extensive elevational range, Sequoia slender salamanders occur in diverse habitats. Along the South Fork Kaweah River within foothill oak woodland at 430 m elevation, salamanders are present on or at the base of a mesic, north-facing slope bordering a stream. Local vegetation includes California buckeye, California sycamore, white alder, Fremont cottonwood, western redbud, and interior live oak, with blue oak characteristic of the bordering exposed slopes (Jockusch et al., 1998). Salamanders occupy moist, moss-covered talus. Both Sequoia slender salamanders and gregarious slender salamanders (B. gregarius) occur here, but the latter’s range extends into drier habitats.
At somewhat higher elevations (1,200 m) along the South Fork of the Kaweah River, Sequoia slender salamanders occur under fallen tree limbs and surface litter in mixed conifer forest.
At one high elevation site (2,205 m) near Silver City, Sequoia slender salamanders were found under rocks on wet gravel at a perennial spring flowing over a west-facing slope. Vegetation in and near the spring includes willows, currant, white fir, and manzanita.
At a second high-elevation site (2,200 m), salamanders were found beneath wet logs resting on wet soil in a shaded draw about 5 m from a brook. The heavily forested slope was grown to sugar pine, incense cedar, giant sequoia, alders, and ferns.
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Sequoia slender salamanders occur over a wide elevational range and periods of surface activity vary considerably with local rainfall and temperature. At low elevation sites, salamanders are present under surface cover from November to March–April. This window of activity is extended for middle elevations, but with salamanders retreating underground during the coldest periods of December–January. At high elevation sites (≥ 2,000 m), surface activity probably is confined to May–October. Field body temperatures of salamanders found under cover at two high-elevation sites averaged 13.2 ˚C (range = 12.0–15.0 ˚C, n = 9; R.W.H., unpublished data).
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). Unknown.
K. Interspecific Associations/Exclusions. There is extensive range overlap between Sequoia slender salamanders and gregarious slender salamanders within the Kaweah River system, and cases of sympatry are known. Although confirmed from only six localities, Sequoia slender salamanders likely have a larger distribution within the Kaweah River drainage than present records indicate.
Sequoia slender salamanders are found occasionally with Sierra Nevada ensatinas (Ensatina eschscholtzii platensis); California newts (Taricha torosa) are widespread at lower elevations in the Kaweah River drainage and commonly are found at sites where Sequoia slender salamanders occur.
We expect to find Sequoia slender salamanders in sympatry with both Kings River slender salamanders (B. regius) and relictual slender salamanders (B. relictus), but as yet these members of the same species group are not known to occur together.
L. Age/Size at Reproductive Maturity. This is a moderately small species of Batrachoseps, with maximum adult sizes ≤ 50 mm SVL (Jockusch et al., 1998). Age and size at sexual maturity are unknown.
M. Longevity. Unknown.
N. Feeding Behavior. Has not been described, although all Batrachoseps species observed thus far use a projectile tongue to capture small invertebrates.
O. Predators. Unknown. Ring-necked snakes (Diadophis punctatus) occur in the lower elevation portion of the range of Sequoia slender salamanders and should be considered likely predators.
P. Anti-Predator Mechanisms. Immobility, coiling, and flipping have been observed when salamanders are first uncovered (R.W.H., unpublished data). The dark dorsal coloration presumably is cryptic when viewed against dark substrates and in low-light environments.
Q. Diseases. Unknown.
R. Parasites. Unknown.
S. Comments. Populations now identified as B. kawia previously were placed within B. relictus (Brame and Murray, 1968) or B. pacificus relictus (Yanev, 1978, 1980). Although Yanev noted the distinctiveness of the Kaweah River populations, these were not elevated to full species status until recently (Jockusch et al., 1998), when the formerly wide-ranging B. relictus was partitioned into four species (from north to south in the central and southern Sierra Nevada): B. diabolicus, B. regius, B. kawia, and B. relictus. Recent mtDNA studies suggest a sister-taxon relationship between B. kawia and B. relictus (Jockusch, 1996; Jockusch et al., 1998).
Jockusch et al. (1998) tentatively assigned specimens from Summit Meadow, Fresno County, to B. kawia, but we now believe that this population represents B. regius.
4. Conservation. The majority of Sequoia slender salamander populations occur on public lands administered by the USDA Forest Service or National Park Service. They thus enjoy some measure of habitat protection, although Forest Service lands are subject to various uses including timber harvest and grazing. Based upon available data, this species appears to have a very restricted range comprised of disjunct, quite localized populations. Additional field surveys are needed throughout the Kaweah River drainage to better define the distributional limits of this species and thereby offer informed opinions regarding possible protection measures.
1 Robert W. Hansen
2 David B. Wake
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 23 Jan 2019.
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