Predation on artificial bird nests in chaparral fragments.

The predation rate of artificial bird nests was measured in disturbed chaparral habitat fragments and at an unfragmented site in coastal San Diego County, California USA. Local extinctions of chaparral birds has been previously shown to occur in these fragments. The predation rate was highest at the unfragmented site. Among fragments, predation was higher at moderately disturbed than at highly disturbed sites. These results suggest that nest predator species diversity or density is reduced in disturbed chaparral fragments. Nest predation is probably not the most important cause of the observed loss of chaparral breeding bird diversity in these fragments.