About the Authors

P. Dee Boersma

boersma@u.washington.edu.

Affiliations Department of Biology, University of Washington, Seattle, Washington, United States of America, Wildlife Conservation Society, Bronx, New York, United States of America

Ginger A. Rebstock

Affiliations Department of Biology, University of Washington, Seattle, Washington, United States of America, Wildlife Conservation Society, Bronx, New York, United States of America

Competing Interests

The authors received donations of field equipment from two commercial sources (Trimble and Canon), but neither company (nor any of our funders) has any claims or restrictions on the data or results. Therefore, this does not alter the authors′ adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: PDB. Performed the experiments: PDB GAR. Analyzed the data: GAR. Wrote the paper: PDB GAR.