Carlsbad Fish and Wildlife Office Grant: California Gnatcatcher & Coastal Cactus Wren Population Analysis

The Service has been conducting California gnatcatcher surveys at a landscape level, across preserve lands, in San Diego County. Surveys were completed in 2004, 2007 and 2009. Data collected includes gnatcatcher surveys, vegetation transect data, and GIS information; all collected at the same geo-reference points. These data have been analyzed by survey year, but have not been analyzed with respect to time.
An analysis of these data will be conducted to inform managers of population trends and habitat parameters that may influence the presence or absence of gnatcatchers.

The specific objectives of the gnatcatcher study are:

1. Calculate population estimates to determine gnatcatcher trends across San Diego County.

2. Construct occupancy models to classify habitats across San Diego County with regard to the probability of occupancy by gnatcatchers.

3. Construct population models to inform managers of specific habitat parameters for which land can be managed.

4. Construct population models to assist planners to prioritize lands for conservation relevant to conservation objectives and preserve design.

5. Construct colonization/extinction models to inform biologist of patterns of occupancy over time.

6. Evaluate the impacts of the 2003 wildfires on gnatcatcher occupancy across San Diego County.

7. Evaluate and review the study design used during 2004, 2007 and 2009 surveys as to its efficiency for future use with respect to conservation objectives in San Diego County. Make design recommendations for future survey years.
The Service conducted landscape level surveys for coastal cactus wrens in San Diego County during 2009 and 2011. Data collected includes cactus wren surveys, vegetation community parameters including detailed area maps of cactus, and the physical parameters of survey locations as cataloged by GIS; all collected at the same geo-reference points. These data have not been analyzed.

The specific objectives of the cactus wren study are:

1. Construct occupancy models to classify habitats across San Diego County with regard to the probability of occupancy by cactus wrens.

2. Construct population models to inform managers of specific habitat parameters for which land can be managed.

This CESU Cooperative Project Agreement will build on previous research conducted by the Recipient in the area of population ecology with an emphasis experimental design, analysis, and estimation. This cooperative agreement will also provide opportunity for the Service, through the Carlsbad Fish and Wildlife Office, to contribute its expertise on coastal sage scrub ecological research to applied conservation problems relative Habitat Conservation Plans in southern California. Thus, the results of this research will also assist the Service in the prioritization of conservation actions and strategies for the California gnatcatcher and coastal cactus wren.

The Recipient will also involve other faculty and graduate students, as appropriate and feasible. The Recipient and the Service will jointly publish manuscripts of the study in peer-reviewed journals.