Targeted Bird Surveys - Orange County - Nature Reserve [ds430]

The Nature Reserve of Orange County (NROC) is an open space network within the central and coastal Orange County NCCP/ HCP area, which supports roughly 4,000 hectares (9,884 acres) of coastal sage scrub (CSS) habitat. A target bird monitoring study was developed by the reserve's Technical Advisory Committee (TAC) and a biometrician in consultation with the US Fish and Wildlife Service and the California Department of Fish and Game. The goal of the study is to monitor California Gnatcatcher and Cactus Wren populations (target species of the NCCP) and determine whether the NCCP/HCP has been successful in conserving the species. These data will also establish a baseline for future research in order to track long-term changes in the populations of these two species and will help guide NROC adaptive management activities. This data layer represents the locations of California Gnatcatcher and Cactus Wren sightings within reserve lands from 1999-2004. Portions of NROC lands containing over 50% CSS were partitioned into potential monitoring sites of approximately 20 ha (49 acres) by an Orange County GIS Analyst. TAC staff used a random number generator to select 20 sites within the central reserve and 20 sites within the coastal reserve as monitoring locations. These sites were further stratified to represent "reserve core", "reserve edge", and "reserve fragment" habitats (Hamilton 2003a). Surveys were conducted by walking slowly through monitoring locations and pausing at intervals to play tapes of the California Gnatcatcher and Cactus Wren and then watching and listening for responses. Locations of all target bird sightings were mapped and information on gender and group size was noted when possible, along with vegetative composition of occupied habitats. Presence of Brown-headed cowbirds, which are known to parasitize nests of California Gnatcatcher, was also recorded. Habitat-related vegetation parameters of occupied territories, such as dominant plant species, were also recorded and are available upon request. In 1999, all 40 sites were visited once from February 1 - May 31. In 2000, 16 sites were visited once and 24 sites were randomly selected to be visited three times from March 15 - June 30. In 2001, all 40 sites were visited twice and 24 sites (same sites as in 2000) were visited three times, also from March 15 - June 30. From 2002-2004, site monitoring was the same with minor changes to 4 sites and was conducted from March 1 - June 30. See Hamilton 2003a, 2003b, 2003c, and 2004 for further discussion of site establishment and monitoring study protocols.

For use by California Department of Fish and Wildlife (CDFW) staff and California Natural Diversity Database (CNDDB) subscribers. Due to the sensitive status of the species in this data, CDFW policy restricts its access.

Disclaimer: The State makes no claims, promises, or guarantees about the accuracy, completeness, reliability, or adequacy of these data and expressly disclaims liability for errors and omissions in these data. No warranty of any kind, implied, expressed, or statutory, including but not limited to the warranties of non-infringement of third party rights, title, merchantability, fitness for a particular purpose, and freedom from computer virus, is given with respect to these data.