Cooperative Ecosystem Studies Unit, Californian CESU: Arthropod Prey Availability Study for Cactus Wrens in San Diego County

This project is aimed at gaining a better understanding of arthropod prey availability in Coastal Cactus Wren (Campylorhynchus brunneicapillus) territories in southern San Diego County, California. Cactus Wren populations in this region have steadily declined over the last decade, possibly in response to drought-associated reductions in prey availability which in turn could be reducing wren fecundity and/or survival of young and adults. Food availability for Cactus Wrens may be affected by habitat quality, as characterized by the composition and abundance of native and non-native plant species and amount of bare ground. During drought years, wrens in territories with poor quality habitat may be even more food limited, making them more vulnerable to decline. Improving habitat quality could thus be a way to increase food availability and enhance wren productivity and survival. Developing management strategies to increase stability of wren populations in years with low rainfall is of particular importance if droughts become more frequent, intense and prolonged in the future, as predicted by climate change models.