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Using automated radio telemetry to quantify activity patterns of songbirds during stopover
- Schofield, Lynn N., Deppe, Jill L., Zenzal, Theodore J., Ward, Michael P., Diehl, Robert H., Bolus, Rachel T., Moore, Frank R.
- TheAuk 2018 v.135 no.4 pp. 949-963
- Catharus ustulatus, Hylocichla mustelina, Vireo, automation, autumn, coasts, energy expenditure, flight, habitats, migratory behavior, predation, radio telemetry, risk assessment, songbirds, stopover sites, temperature, wind speed, Gulf of Mexico
- During migration, birds require stopover habitat to rest and refuel before resuming flight. While long-distance migratory flights represent a large energy investment, stopover accounts for roughly two-thirds of a bird's total energy expenditure during migration. Therefore, birds should minimize energy expenditure while also minimizing time and predation risk during stopover. To understand activity during migration, we recorded activity patterns (i.e. fine-scale movements associated with a range of behaviors) of 3 species, Red-eyed Vireo (Vireo olivaceus), Swainson's Thrush (Catharus ustulatus), and Wood Thrush (Hylocichla mustelina), at a stopover site along the northern coast of the Gulf of Mexico during autumn migration using automated radio telemetry. We found Red-eyed Vireos to be the most active and Swainson's Thrushes the least active. For each species, we used boosted regression trees to investigate associations between activity and factors known to influence bird behavior during stopover. While species differed, day of year and temperature were important predictors of activity for all species. Vireos were active early in the season, under light winds and warmer temperatures, and on evenings when winds were more favorable. Thrushes were more active as the season progressed and when temperatures were cooler. Thrush activity also differed between years, although thrushes increased activity later in the season during all years. Our results illustrate automated radio telemetry as a unique and valuable tool for understanding fine-scale behaviors of birds during stopover.