Coastal Cactus Wren - San Diego Co. - 2011 [ds708]

The San Diego Multiple Species Conservation program (MSCP) was developed for the conservation of plants and animals in the southeast portion of San Diego County. Monitoring of species found within the MSCP is a key method to measuring the success of the reserve system. The Coastal Cactus Wren is one of the focal species identified as part of the MSCP Biological Monitoring Plan. The species is also currently on the State of California Birds of Species Concern list. The primary threat to the cactus wren is habitat loss and concurrent fragmentation, which occurs as habitat is developed or fire destroys cactus. The coastal cactus wren historically occurred in cactus patches along the several lagoons and coastal canyons in San Diego and southern Orange County (Rea and Weaver 1990), though recent surveys reveal that most of these populations have been destroyed by urbanization (Rea and Weaver 1990, USFWS 1994). The remaining coastal cactus wren populations in San Diego County are predominantly in the inland portion of the county (Rea and Weaver 1990). This datalayer presents the positive observations of USFWS Cactus Wren occupancy surveys conducted in San Diego County in 2011 and was compiled as part of the Southern California Data Integration Project. Extensive cactus mapping was conducted in San Diego County prior to the survey effort. Cactus wren monitoring was done within an occupancy framework to determine the percentage of plots occupied by cactus wrens, estimated from plot surveys. Surveys were conducted from April 26-June 7, 2011 between sunrise and sunset. Each plot was visited up to 3 times during the survey season. Environmental measurements (air temperature, average wind speed) were recorded during a 1-minute period upon arriving at a sample point using a pocket weather station. Surveys were not conducted if average wind speeds exceeded 20 kilometers per hour, precipitation exceeded a drizzle, or ambient temperatures were less than 4.5C (40F) or over 30C (85F). Surveyors used tape playback of cactus wren song to elicit response of cactus wrens on the plot to aid detectability. Following Mitrovich and Hamilton (2007), the tape was played for three 40 second intervals with one minute of silence in between. The surveyor listened and watched for cactus wrens as the tape was played and for one minute after each tape playback. Presence or absence of cactus wrens on the plot was recorded on a datasheet, as well as the number of juveniles, adults, or birds in which the life stage could not be determined. Additional information about the survey or bird was noted in the Comments field, such as whether a nest was observed. Habitat data were collected for each plot as well but are not presented here. REFERENCES Mitrovich, M.J., and R.A. Hamilton. 2007. Status of the Cactus Wren (Campylorhynchus brunneicapillus) within the Coastal Subregion of Orange County, California. Prepared for Nature Reserve of Orange County, Irvine, California. May 2007. Rea, A. M., and K. L. Weaver. 1990. The taxonomy, distribution, and status of coastal California cactus wrens. Western birds 21:81-126. U.S. Fish and Wildlife Service. 1994. One year finding for a petition to list the Pacific coast population of the cactus wren under the Endangered Species Act. 50 CFR Part 17 (FR Doc 94-21785, Filed 9-1-94).

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