Article abstract: Rapid urbanization has led to the loss and degradation of riparian habitats in southern California. In response to the need to protect and manage habitat for native species in the South Coast Eco-Region of Southern California, the Natural Communities Conservation Planning Program (NCCP) was initiated in 1991. The arroyo toad (Bufo californicus) and western pond turtle (Clemmys marmorata) are covered species in the San Diego Multiple Species Conservation Program (MSCP). However, the current status and distribution of the arroyo toad and the western pond turtle within the MSCP is poorly known. Direct habitat loss in conjunction with hydrological alterations and the introduction of nonnative species have caused arroyo toads to disappear from about 75% of previously occupied habitat within the United States. The western pond turtle is the only turtle native to southwestern California and was historically abundant in most major drainages in San Diego County. Surveys conducted in southern California in the late 1980's suggested that pond turtles no longer occurred in many historic locations and that few viable populations of turtles remained. The US Geological Survey conducted surveys for the arroyo toad and western pond turtle at select sites within the San Diego MSCP in 2002. Arroyo toads were observed at two of the 7 sites surveyed and western pond turtles were detected at 3 of the 26 sites surveyed. A suite of non-native aquatic predatory species known to have deleterious effects on native amphibian species was detected at 46% of the sites that contained surface water during the surveys. Non-native turtles were detected at more locations than western pond turtles. Western pond turtles co-occur with nonnative turtles at least at one location. Surveys for both, arroyo toads and western pond turtles will continue during spring and summer 2003.
Number of pages: 39
Authors: Meyer, Kathie; Ervin, Edward; Madden-Smith, Melanie; Hathaway, Stacie; Fisher, Robert N.;
Prepared for: California Department of Fish and Game; County of San Diego;
Prepared by: U.S. Geological Survey, San Diego Field Station;
Keywords: arroyo toad; endangered; MSCP; NCCP; southwestern pond turtle;