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Literature Review

Desert slender salamander

Batrachoseps aridus

USFWS: Endangered
CDFG: Endangered

Background

Distribution, Abundance and Trends. B. aridus is known from only two canyons in the Santa Rosa Mountains, the entire occupiable habitat comprising perhaps several acres. In addition to the population at Hidden Palms Oasis, an additional population of slender salamanders was found in the vicinity of Guadalupe Creek, in a canyon separated from Hidden Palms by 4.5 miles of continuous desert (Duncan and Esque 1986). Comparative genetic analysis of the two populations has not been completed but preliminary results have confirmed that Guadalupe Creek is a disjunct population of B. aridus (K. Nicol, pers. comm.).

There is no indication that the geographic range of the species has declined historically. The current range has probably changed little since shortly after the last pluvial period, about 10 million years ago. The habitat of B. aridus is a steep-walled desert canyon with permanent water seeping from fractured bedrock. The species uses cracks in the bedrock and sheet-like limestone deposits for shelter from desiccation and temperature extremes. The combination of permanent water, shade, and availability of retreat sites appears important to the distribution of the species. The area receives only 8 inches of rainfall annually (M. Fisher, pers. comm.), and the dry hillsides adjacent to the seeps are uninhabitable by the salamander.

Perennial plants in the canyon from where the species is known include desert fan palm, Washingtonia filifera; southern maidenhair fern, Adiantum capillus-veneris; narrow-leaved willow, Salix exigua; squaw waterweed, Baccharis sergiloides; honey mesquite, Prosopis glandulosa; and sugarbush, Rhus ovata (Zabriskie 1980). Common perennial plants on the hillsides surrounding the canyon include desert agave, Agave deserti; big galleta grass, Pleuraphis (Hilaria) rigida; desert apricot, Prunus schottii; desert tea, Ephedra aspera; Santa Rosa sage, Salvia eremostachya; buckhorn cholla, Opuntia acanthocarpa; California barrel cactus, Ferocactus cylindraceus (acanthodes); creosote Larrea tridentata; Jojoba, Simmondsia chinensis; and catclaw acacia, Acacia greggii. (Zabriskie 1980, Hickman 1993).

Little is known specifically about the natural history of B. aridus. Most sightings have been in the period from late February to early April. Information from the California Department of Fish and Game indicates that they are active year round and that there does not seem to be any seasonal preference. Like its congeners, B. aridus lacks an aquatic larval stage; instead, eggs are laid in moist soil and hatch as fully developed young. Other species of Batrachoseps eat primarily small arthropods.

Threats and Limiting Factors. The major threats to the species involve degradation of habitat. Although the area is closed to public access, it is still susceptible to damage by vandals and illegal collectors. In addition, the water that feeds the seep comes from the northwest near Asbestos Mountain. This recharge area includes undeveloped BLM, USFWS and CDFG land as well as portions of the communities of Pinyon Crest, Royal Carrizo, and Chapman Ranch (Denver 1990). Water use by these communities may significantly decrease water available to the salamander. Also, water quality may degrade as nitrates and nitrites enter the water from septic systems. Invasion of the habitat by exotic plants such as tamarisk is another potential threat.

Special Considerations. The entire population of the desert slender salamander, worldwide, is contained within the Plan area. Thus, survival of the species depends on the protection of this population. The canyon and surrounding desert hills are habitat for the peninsular bighorn sheep, Ovis canadensis, and protection of habitat for this species will greatly benefit the desert slender salamander. Desert fan palm oasis woodland is a natural community contained within salamander habitat.