About the Authors
Department of Environmental Studies, University of California Santa Cruz, Santa Cruz, California, United States of America
Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: JAJ RG DKL. Performed the experiments: JAJ. Analyzed the data: JAJ. Contributed reagents/materials/analysis tools: JAJ RG. Wrote the paper: JAJ. Revised the article: RG DKL.