Tehachapi Slender Salamander
© 2006 William Flaxington (1 of 12)
Batrachoseps stebbinsi Brame and Murray, 1968
Robert W. Hansen1
1. Historical versus Current Distribution. Tehachapi slender salamanders (Batrachoseps stebbinsi) are known from two small areas in south-central California, both in Kern County. Within Caliente Canyon (site of the type locality), at the junction of the Sierra Nevada and Tehachapi Mountains, Tehachapi slender salamanders have been recorded from seven discrete localities at elevations of 550–790 m (Brame and Murray, 1968; R.W.H., unpublished data).
Populations tentatively allocated to B. stebbinsi also occur in several isolated canyons on the northern slopes of the Tehachapi Mountains, ranging from Tejon Canyon southwest to Fort Tejon, at elevations of 945–1,430 m (Yanev, 1980; Stebbins, 1985; Jockusch, 1996; Wake, 1996; Wake and Jockusch, 2000; R.W.H., unpublished data).
A single specimen was collected in 1957 from the north slope of Black Mountain (914 m), in the vicinity of Tehachapi Pass, an area that is geographically intermediate between the Tehachapi Mountains populations and Caliente Canyon sites (Brame and Murray, 1968). The Tehachapi Pass site, along the route of old U.S. Highway 466, was thought to have been buried by new highway construction (Brame and Murray, 1968). However, the original collector reports that the site remains relatively undisturbed (T.J. Papenfuss, personal communication), although no Batrachoseps have been found anywhere in Tehachapi Pass since 1957.
2. Historical versus Current Abundance. Populations of Tehachapi slender salamanders are confined to seasonally shaded, north-facing slopes of canyons located in otherwise arid to semi-arid terrain. Individual populations are small and localized. Within Caliente Canyon, much of the known salamander habitat occurs on public lands administered by the U.S. Bureau of Land Management. Some sites have been affected by road construction, mining, and cattle grazing, and potentially by flood control projects (Hansen and Stafford, 1994b; Jennings, 1996b). Portions of the Tehachapi Mountains (notably Bear, Cummings, and Tehachapi Valleys) are experiencing rapid human population growth, with much development occurring in the foothills. Plans exist for the development of several new communities on the vast Tejon Ranch property. Owing to the small size and localized nature of Tehachapi slender salamander populations, the Tejon Ranch sites appear especially vulnerable to habitat disturbance.
The construction of a major freeway through Grapevine Canyon (Tejon Pass) at the western edge of the Tehachapi Mountains undoubtedly has impacted populations of Tehachapi slender salamanders. Although the occurrence of Tehachapi slender salamanders within the Tejon Pass region has been confirmed only from the vicinity of Fort Tejon, potential habitat is present at additional sites to the north.
Much of the Tehachapi Mountains and adjoining areas are inaccessible owing to a combination of rugged terrain and private ownership, and knowledge of the distribution of populations allied to B. stebbinsi is sketchy. Preliminary ground and aerial surveys indicate the presence of potential habitat in a number of unexplored canyons on the south side of Cummings Valley, the northwest slope of Bear Mountain (e.g., Clear and Sycamore creeks), elsewhere on the north slopes of the Tehachapi Mountains (e.g., Cedar, Chanac, and Tunis creeks), and possibly in some of the canyons on the north slopes of the San Emigdio Range (e.g., Black Bob Canyon) to the west of Fort Tejon.
3. Life History Features.
A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. Unknown. Extensive surface movements within the breeding season, as reported for California slender salamanders (B. attenuatus; Anderson, 1960), seem implausible for this species given that most populations are associated with small, discrete patches of suitable habitat.
Onset of the fall/winter rainy season is especially unpredictable at the extreme southern end of the Sierra Nevada and adjacent Tehachapi Mountains. Periods of surface activity similarly vary from year to year. A possibly gravid female was discovered on 13 February in Caliente Canyon, and another was found on 1 April at Fort Tejon (T. Manolis, personal communication).
ii. Breeding habitat. Unknown.
i. Egg deposition sites. Nest sites have not been found for this species, but it seems likely that eggs are deposited deep within the rock talus/litter matrix characteristic of Tehachapi slender salamander microhabitat. Communal nests have been reported for other members of the B. nigriventris species group (Jockusch and Mahoney, 1997) and might be expected in Tehachapi slender salamanders.
ii. Clutch size. Unknown.
C. Direct Development. Timing of hatchling emergence is unknown.
D. Juvenile Habitat. Unknown how this may differ from adult habitats. Curiously, juvenile Tehachapi slender salamanders rarely are found, suggesting that hatching occurs in spring as surface activity declines and that juveniles may remain well underground.
E. Adult Habitat. Caliente Canyon, lying at the southern end of the Sierra Nevada, is situated in a moderately arid region. Salamanders are restricted to lower margins of north-facing slopes bordering Caliente Creek, as well as a few small side canyons, and are associated with granitic or limestone talus and scattered rocks. Vegetation here consists of foothill pine, interior live oak, canyon oak, blue oak, Fremont cottonwood, sycamore, and California buckeye (Brame and Murray, 1968). At more exposed locations, California juniper, yucca, bush lupine, and buckwheats grow. Substrates range from sandy-gravelly loam to decomposed granite.
In the canyons of the Tehachapi Mountains, Tehachapi slender salamander populations are likewise restricted to north-facing slopes, although they occur at higher elevations. Unlike the Caliente Canyon populations, where salamanders are nearly always associated with rocks, the Tehachapi Mountains salamanders occur in areas of downed wood or talus.
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Tehachapi slender salamanders occur in a region where the timing and amount of winter precipitation is erratic. Surface activity closely tracks the onset of the rainy season (generally November–December), and at lower elevations may be of brief duration (2–3 mo). In years of below average rainfall or consecutive years of drought (not unusual in this region) salamanders may not appear under surface cover at all. Although most of the winter precipitation occurs as rainfall, higher elevation portions of the range regularly receive snow.
Peak surface activity occurs in February–March, extending into April in wet years or early May at higher elevations (e.g., upper reaches of Pastoria and Tejon Creek drainages, Tehachapi Mountains). Field body temperatures for salamanders found under surface cover averaged 10.4 ˚C (range = 5.0–12.0 ˚C, n = 47; R.W.H., unpublished data).
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). Most of the range of Tehachapi slender salamanders experiences below-freezing temperatures during the winter, and salamanders rarely are found under surface cover (i.e., they are likely underground) during such episodes.
K. Interspecific Associations/Exclusions. Yellow-blotched ensatinas (Ensatina eschscholtzii croceater) have been found at all Tehachapi slender salamander localities; they occupy similar habitats, but have a more extensive geographical, elevational, and ecological distribution. Within Caliente Canyon, Tehachapi slender salamanders and yellow-blotched ensatinas are the only salamanders present. However, black-bellied slender salamanders (B. nigriventris) range as far north as Comanche Point on the northern slopes of the Tehachapi Mountains, and a sight record for a Batrachoseps in the semi-arid, open oak woodland along Caliente Creek below Caliente Canyon (J. M. Brode, personal communication) may pertain to this species or possibly gregarious slender salamanders (B. gregarius).
Within the Tehachapi Mountains segment of the range, Tehachapi slender salamanders and black-bellied slender salamanders are sympatric in the Pastoria and Tejon Creek drainages, at Fort Tejon in Grapevine Canyon, and probably elsewhere (Jockusch, 1996; Wake and Jockusch, 2000). Although the ranges of these two species are broadly overlapping, Tehachapi slender salamanders are habitat specialists, confined to moist, north-facing slopes within canyons or ravines, and are associated with scattered rock, talus, or woody debris (Brame and Murray, 1968; Wake, 1996; R.W.H., unpublished data). By contrast, black-bellied slender salamanders enjoy a broader distribution, occurring both in moist, oak-filled canyons, as well as in drier oak woodlands on open hillsides. Both species occasionally have been collected from under the same log. The extensive range overlap between Tehachapi slender salamanders and black-bellied slender salamanders in the Tehachapi Mountains is notable in that it represents the only case of sympatry involving members of the same species group of Batrachoseps (Wake and Jockusch, 2000).
Within the Tehachapi Mountains, yellow-blotched ensatinas occur at all known Tehachapi slender salamanders localities. However, at sites where we have found yellow-blotched ensatinas to be abundant, Tehachapi slender salamanders do not occur. Conversely, at 1,400 m elevation along Pastoria Creek, Tehachapi slender salamanders are locally abundant, and yellow-blotched ensatinas are present but in much lower numbers.
L. Age/Size at Reproductive Maturity. This is a relatively large species of Batrachoseps, with modest female-biased sexual size dimorphism. For a series of 10 large females, mean was 57.0 mm SVL (maximum SVL = 60.4 mm); 10 large males averaged 54.0 mm SVL (maximum SVL = 59.3 mm; both series from Caliente Canyon; data in part from Brame and Murray, 1968). Minimum 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. In Caliente Canyon, a small adult ring-necked snake (Diadophis punctatus) was observed attempting to subdue an adult Tehachapi slender salamander by constriction. The salamander forced the snake to release its hold by moving into rock rubble, where the salamander escaped (Burkhardt et al., 2001).
P. Anti-Predator Mechanisms. Defensive behaviors may include coiling, immobility (crypsis), rapid crawling, and tail autotomy. These behaviors have been observed in populations throughout the range.
Q. Diseases. Unknown.
R. Parasites. Unknown.
S. Comments. For this account, we have included populations currently allocated to B. stebbinsi ranging from Caliente Canyon to Fort Tejon (Wake, 1996). However, high levels of genetic differentiation, as well as differences in coloration and size, between the two principal distributional units of B. stebbinsi (Caliente Canyon versus Tehachapi Mountains) strongly suggest that 2 species are represented (Jockusch, 1996; Jockusch and Wake, 2002; D.B. Wake and colleagues, unpublished data). Ecological information presented in this account has been delineated for the most part with future taxonomic changes in mind.
An earlier report (Richman, 1973) of B. stebbinsi from high elevation on the Kern Plateau of the southern Sierra Nevada (Tulare County) actually represented the first collection of the then-undescribed Kern Plateau salamander (B. robustus; Wake et al., 2002).
Although the description of B. stebbinsi as a new species was relatively recent (Brame and Murray, 1968), recognition of the existence of two species of Batrachoseps in the Tehachapi Mountains appears to have occurred as early as 1858 (Wake and Jockusch, 2000). The naturalist John Xántus, then stationed at Fort Tejon, reported in correspondence to the Smithsonian Institution (reprinted in Zwinger, 1986) that three species of salamanders occurred there, one of which was yellow-blotched ensatinas (Ensatina eschscholtzii croceater; undescribed at the time) and the other two obviously referable to Batrachoseps (Wake and Jockusch, 2000).
4. Conservation. Populations of this narrowly distributed species occur on both private and public lands (the latter including portions of the Caliente Canyon range segment and administered by U.S. Bureau of Land Management) and face a variety of threats as noted above (see “Historical vs. Current Abundance” above). Although listed as Threatened by the State of California, Tehachapi slender salamanders probably warrant some measure of federal protection, given the near-term development pressures in the Tehachapi Mountains. Tehachapi slender salamanders are listed as a Forest Service Sensitive Species and a Federal Species of Concern.
Acknowledgments. We thank John Brode, Amy Kuritsubo, Tim Manolis, and Ted Papenfuss for sharing field observations.
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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