Welcome to the American Ornithological Society 2018 Annual Conference. We are pleased to have you join us at the lovely Hilton El Conquistador Resort in Tucson, AZ.
In North America, most birds perform their annual pre-basic molt immediately following breeding. Migratory behaviors present additional temporal constraints for birds, which have presumably given rise to different strategies for completing their prebasic molt prior to the onset of winter. These strategies include molting before departing the breeding grounds, at one or multiple sites along the migratory route, or after arriving on the wintering grounds. In this study we investigated strategies exhibited by western populations of Swainson's Thrush (Catharus ustulatus) at the landscape scale. We used data from 69 long-term bird banding studies in southern Oregon and northern California to detect where and when individuals were breeding and molting. Specifically, we compared strategies and site fidelity between breeding and non-breeding individuals across the study area. Our results suggest that Swainson's Thrush can molt at both breeding and non-breeding sites, with a lower number of individuals captured molting at breeding sites. The prebasic molt occurred later at non-breeding sites, and individuals captured molting at non-breeding sites had a longer length of stay (average of 15.54 days) than non-molting individuals (4.94). We found that some molting individuals exhibited site fidelity between years at non-breeding sites. Our results suggest that Swainson's Thrush are locally adapted and capable of exhibiting a diversity of strategies, from molting on a breeding territory to exhibiting site fidelity to non-breeding molting grounds.