The following account is modified from Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo (©2005 by the Regents of the University of California), used with permission of University of California Press. The book is available from UC Press.

Batrachoseps simatus Brame and Murray,1968
Kern Canyon Slender Salamander

Robert W. Hansen, David B. Wake

1. Historical versus Current Distribution. Kern Canyon slender salamanders (Batrachoseps simatus) are known only from the lower Kern River Canyon (Kern County) at the southern end of the Sierra Nevada of California. They have been recorded from nine sites within the lower Canyon, ranging from Stork Creek (455 m) to Clear Creek (685 m; Brame and Murray, 1968; Hansen, 1988). They also occur within Erskine Creek Canyon (a tributary to the Kern River) on the northern flank of the adjacent Piute Mountains; here they have been found in three small areas ranging in elevation from 890–1,220 m.

Populations of Kern Canyon slender salamanders appear to be confined to small, disjunct patches of habitat, suggesting that population sizes are quite small. Despite an earlier estimate that total available habitat for Kern Canyon slender salamanders comprised approximately 820 acres (332 ha), salamanders have been recorded only from roughly 17 acres (6.9 ha), about 2% of the potential habitat (Hansen, 1988). Substantial genetic differences between adjacent populations suggest that the apparent isolation is not an artifact of inadequate sampling (D. B. W., unpublished data).

2. Historical versus Current Abundance. The southern end of the Sierra Nevada may experience multi-year droughts, making it nearly impossible to locate specimens of Kern Canyon slender salamanders under surface cover during such periods. Even under favorable conditions, this species can be difficult to find, rendering efforts to monitor the status of local populations problematic. Despite such obstacles, fieldwork over the last two decades suggests that populations at all known localities are extant.

3. Life History Features.

A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. Unknown. Onset of the fall/winter rainy season is especially unpredictable at the extreme southern end of the Sierra Nevada. An initial heavy rainstorm in October or November, which may stimulate salamander surface activity, may be followed by dry conditions lasting 1–2 mo before rains resume. We suspect that timing of courtship and egg laying is similarly variable.
ii. Breeding habitat. Unknown.

B. Eggs.
i. Egg deposition sites. Nest sites have not been found for this species. Communal nests have been reported for other members of the B. nigriventris species group (Jockusch and Mahoney, 1997) and might be expected in B. simatus. The discovery of a communal nest on nearby Breckenridge Mountain (Kern County, at an elevation of 1,920 m; R. W. H., unpublished data) was cited by Stebbins (1985) as representing B. simatus; however, the taxonomic status of the Breckenridge Mountain population is unresolved and it is doubtful that these animals are conspecific with B. simatus.
ii. Clutch size. Unknown.

C. Direct Development. Timing of hatchling emergence is unknown. A single hatchling was observed on 4 March along Clear Creek (685 m).

D. Juvenile Habitat. Unknown how this may differ from adult habitats.

E. Adult Habitat. Within the lower Kern River Canyon, populations of Kern Canyon slender salamanders occur mostly in smaller tributary canyons or ravines at the base of the north-facing slope within a pine-oak woodland. These areas receive little or no direct sunlight during the winter, and cool, moist conditions are likely to persist later in the spring. Predominant plant species include foothill pine, interior live oak, sycamore, California buckeye, Fremont cottonwood, and willow.

Understory vegetation commonly includes poison oak, nettles, miner’s lettuce, Nemophila sp., Phacelia sp., and grasses (Hansen, 1988). Salamanders have been found under rocks, under and within logs, or in moist oak and sycamore litter. Collection sites range from the wet margins of creeks and seepages to fairly exposed hillsides among chaparral vegetation (Brame and Murray, 1968; Hansen, 1988).

Along Clear Creek near Miracle Hot Springs (685 m elevation), Kern Canyon slender salamanders are associated with talus derived from metamorphic outcroppings. The surrounding slopes support interior live oak, California juniper, foothill pine, yucca, and beavertail cactus. In Erskine Creek Canyon (890–1,220 m elevation), Kern Canyon slender salamanders are closely associated with localized groves of canyon live oak, in areas bordered by dry slopes of foothill pine, interior live oak, and chaparral shrubs such as manzanita, deer brush, and Great Basin sagebrush.

F. Home Range Size. Unknown.

G. Territories. Unknown.

H. Aestivation/Avoiding Desiccation. Salamanders are present under surface cover only during periods of adequate soil moisture—November to March–April. However, the timing of winter rains is erratic in the southern Sierra Nevada, such that conditions suitable for surface activity are shorter, often February–March in the lower Kern River Canyon and somewhat later for the higher elevation sites in Erskine Creek Canyon. Within the rainy season, periods of surface activity tend to be brief, and salamanders can be difficult to find. Field body temperatures for salamanders found under surface cover averaged 10.1 °C (range = 8.8–15.0 °C, n = 40; R. W. H., unpublished data).

I. Seasonal Migrations. Unknown.

J. Torpor (Hibernation). We have not recorded surface activity at substrate temperatures below 8.8 °C.

K. Interspecific Associations/Exclusions. Relictual slender salamanders (B. relictus) formerly were sympatric with Kern Canyon slender salamanders at two sites in the lower Kern River Canyon (Brame and Murray, 1968), prior to their apparent extirpation there. Although these two species were sometimes found in close proximity, relictual slender salamanders were invariably restricted to aquatic microhabitats. Populations assignable to gregarious slender salamanders (B. gregarius) occur just below the mouth of the Kern River Canyon in semiarid grassland (Jockusch et al., 1998), and suitable habitat extends into the Canyon as well, especially along the northern slopes. Yellow-blotched ensatinas (Ensatina eschscholtzii croceater) have been found at most Kern Canyon slender salamander localities; they occupy similar habitats but have a more extensive geographical, elevational, and ecological distribution. Sympatry with California newts (Taricha torosa) occurs along Mill Creek just above its confluence with the Kern River.

L. Age/Size at Reproductive Maturity. This is a moderately large species of Batrachoseps, with adults commonly exceeding 50 mm SVL. Including only animals ≥ 40 mm SVL, a series of adult males from the lower Kern River Canyon averaged 47.3 mm SVL (maximum = 53.8 mm SVL, n = 17), while the average SVL for females was 48.1 mm (maximum = 58.5 mm SVL, n = 9; Brame and Murray, 1968; Wake et al., unpublished data). Animals from Erskine Creek Canyon are markedly smaller: three adult males averaged 39.2 mm SVL (range 38.7–40.2), while four adult females averaged 39.6 mm SVL; one unsexed individual measured 43.0 mm SVL. The mean SVL for the 20 largest animals (sexes combined) from lower Kern River Canyon localities was 52.2 mm, while the mean SVL for the 10 largest specimens from Erskine Creek Canyon was 39.3 mm (D. B. W. and colleagues, unpublished data).

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. Predation is undocumented, although ring-necked snakes (Diadophis punctatus) occur throughout the southern Sierra Nevada and presumably prey on this species.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Apr 2024.

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