Type: report

Article abstract: A study to determine the current status of the California gnatcatcher (Polioptila californica) was conducted in the Central and Coastal Reserves in 2011. The purpose of this study was to establish a baseline population estimate of habitat occupancy for the California gnatcatcher throughout the reserve system in order to evaluate trends in occupancy over time and in response to management actions. A plot based transect approach was used to survey for the California gnatcatcher throughout the Central and Coastal Reserves. A total of 149 randomly selected plots were surveyed for occupancy by California gnatcatchers three times each. Data were also collected on the vegetation types in each plot, including the composition and estimated cover of the dominant shrubs in the coastal sage scrub, which will allow the NROC to develop and evaluate habitat suitability models for the California gnatcatcher. Incidental observations of California gnatcatchers (outside the plots), cactus wrens ( Campylorhynchus brunneicapillus), and other covered species were recorded throughout the study period. California gnatcatchers were detected at a total of 34 plots during the three rounds of surveys. Twenty-four plots were occupied during the first round of surveys, 22 during the second round, and 22 during the third round. The distribution of gnatcatchers is highly skewed toward the Coastal Reserve where 24 of the 34 occupied plots were located. This appears to be the result of the 2007 fires that burned approximately 75% of the Central Reserve. Early successional shrub species, primarily deerweed (Lotus scoparius) and bushrnallow (Malacothamnus fasciculatus ), dominated many of the plots in the bum areas but do not provide quality nesting habitat. These relationships will be investigated more fully by NROC and USFWS when data are analyzed statistically. A substantial number (136) of incidental observations of 18 other target and covered species were made during study. These incidental observations included 25 locations for California gnatcatchers (mostly pairs and individuals) outside of survey plots.