Research
Reconnaissance Surveys Amphibian and Reptile Species Tejon Ranch Conservancy Acquisition Areas (March 2011)
By Live Oak Associates, Inc. (Mark R. Jennings, PhD and David J. Hatesveldt)
Dr. Mark Jennings coordinated reconnaissance level surveys for amphibians and reptiles in 2009-2010 on five tracts of property (i.e., White Wolf, Old Headquarters, Bi-Centennial, Tri-Centennial, and Michener) slated for potential acquisition by the Tejon Ranch Conservancy. Surveys were conducted during the early fall of 2009 and 2010 and the spring of 2010. Assisting Dr. Jennings were Dr. Michael White and Chris Niemela of the Tejon Ranch Conservancy, Mr. Neal Kramer of Live Oak Associates, Inc., and members of the California chapter of the North American Field Herping Association.
Habitats of the Tehachapi Mountains support a considerable diversity of amphibian and reptile species. Based on a review of the available literature it has been determined that as many as 9 species of amphibians and 49 species of reptiles could occur within the boundaries of the Tejon Ranch. None of the five acquisition tracts examined in this study support all 9 amphibian or all 49 reptile species. The diversity of amphibian species occurring on the ranch is generally greatest on the west side of the Tehachapi Mountains. The diversity of reptile species occurring on the ranch is generally the greatest on the east side of the Tehachapi Mountains.
During reconnaissance level surveys conducted in 2009 and 2010, a number of amphibian and reptile species presumed to have been historically present on the proposed acquisition tracts were observed. Three native amphibian species and 21 native reptile species were observed during the three survey periods. One non-native amphibian, the American bullfrog (Rana catesbeiana), was also observed. At least one state and federally listed species, the blunt-nosed leopard lizard (Gambelia sila), was observed in one of the tracts of the Ranch. An assessment of habitats present on the Ranch reveals a high likelihood that other state and federally listed species would be present, including the California red-legged frog (Rana draytonii) and desert tortoise (Gopherus agassizii). In terms of their overall value to special status amphibians and reptiles, the tracts would be ranked as follows: 1) Old Headquarters, 2) Tri-Centennial, 3) Bi-Centennial, 4) White Wolf, and 5) Michener.
Anthropogenic threats to native amphibian and reptile diversity within the five tracts are a real and significant concern. Introduced bullfrogs were observed in aquatic habitats of the Old Headquarters tract by Dr. Jennings and the survey team. It is likely to be present in aquatic habitats potentially present in other tracts of the Ranch. This species is predatory on some native amphibians and poses a threat to native amphibian diversity of the Tejon Ranch. The reintroduction of some native listed amphibian and reptile species to various tracts of the Ranch would be more likely to succeed if bullfrog populations were eliminated from the Ranch, or at a minimum, controlled. A plan for managing current sport fishing on the Ranch with the express purpose of preventing the accidental introduction of additional species of predatory fishes and amphibians would benefit existing populations of amphibians, as well as those that may be reintroduced.
