Type: report

Article abstract: Rapid urbanization has led to the loss and degradation of riparian habitats within the Southern California Coastal Sage Scrub Region. In response to the need to protect and manage riparian and other sensitive habitats in southern California, the Natural Communities Conservation Planning (NCCP) Act was enacted in 1992. The San Diego County subregional plan under the NCCP is the San Diego County Multiple Species Conservation Program (MSCP). The MSCP has been designated to protect such sensitive species as the arroyo toad (Bufo californicus) and western pond turtle (Emys marmorata) within its boundaries by preserving lands with known populations, controlling non-native species, minimizing human impacts, and restoring or enhancing native habitats. Direct habitat loss in conjunction with hydrological alterations and the introduction of non-native species has caused the arroyo toad to disappear from about 75% of previously occupied habitat (Jennings & Hayes 1994) and has resulted in a decrease in the number of viable populations of the western pond turtle in southern California (Brattstrom & Messer 1988; Jennings et al. 1992; Jennings & Hayes 1994). Prior to this study, little was known about the current status and distribution of the arroyo toad and the western pond turtle within the San Diego MSCP lands. In 2002 and 2003 the U. S. Geological Survey conducted focused surveys for the arroyo toad and western pond turtle within nine watersheds of San Diego County, eight of which fall within the MSCP boundaries. Daytime arroyo toad habitat surveys were conducted at 39 sites. Eighteen of these sites were determined to have potential for supporting arroyo toads because of the presence of suitable habitat and/or the close proximity of historical locality record(s) and were surveyed nocturnally for the presence of arroyo toads. Arroyo toads were located at five sites, all but one were previously known locations and all were within the MSCP boundaries. Visual and/or trapping surveys were conducted for western pond turtles at 68 sites for a total of 67 visual and 45 trapping surveys. Western pond turtles were detected at nine sites, six of which are within the MSCP boundaries, and all locations but one were previously known. Population sizes of both species appear to be small. Although mark-recapture data were not collected for arroyo toads and it is not possible to make population estimates, 18 was the largest number of arroyo toads detected at a site during the course