Trends in riparian songbirds banded at Big Sur, central California coast

Abstract

We assessed trends in rates of capture of eight riparian songbirds mist-netted over 17 years (1993-2009) at Big Sur, on the central California coast. The Warbling Vireo (Vireo giluus) and Yellow Warbler (Dendroica petechia) declined significantly, whereas the Swainsons Thrush (Catharus ustulatus) showed a nearly significant increase. Rates of capture of the Willow Flycatcher (Empidonax trailla), Wilson's Warbler (Wilsonia pusilla), Common Yellowthroat (Geothlypis trichas), Yellow-breasted Chat (Icteria uirens), and Black-headed Grosbeak (Pheucticus melanocephalus) were stable. Negative trends for the Warbling Vireo and Yellow Warbler were particularly strong for hatching-year birds, indicating that factors acting in the breeding season were responsible for declines. We captured high ratios of transients to local adults, and at Big Sur trends for some of these species are associated more with populations breeding in other regions. However, in the Swainson's Thrush and Wilson's Warbler, we observed significant increases in local adults and local hatching-year birds, indicating the importance of local riparian habitat for some species at Big Sur.