Demography of a declining population of Warbling Vireos in coastal California

We investigated population trends, adult survival, and productivity indices of a breeding population of Warbling Vireos (Vireo gilvus) in north coasta l California using capture-recapture data from 19 years of standardized mis t-netting conducted at Point Reyes National Seashore. We found significant long-term declines in abundance of both breeding and migratory Warbling Vir eos. In addition, we found a significant long-term decline of hatching-year birds captured during the breeding season. The number of new adults in a g iven year, defined as those birds not previously banded and assumed to be a n index of adult recruitment, was significantly correlated with the capture rate of hatching-year birds in the previous year, suggesting a link betwee n reproductive success and adult abundance and recruitment. Our analysis of capture-recapture data provided an estimate of 50.4% for adult annual surv ival, similar to estimates for other species in stable populations. We coul d detect no temporal trend in survival. Nest survivorship from areas near o ur netting site was relatively low. We suggest that the decline of breeding and migratory populations of Warbling Vireos observed in coastal Californi a may be the result of low productivity on the breeding grounds.