About the Authors

Steffen Oppel

steffen.oppel@rspb.org.uk

Affiliation RSPB Centre for Conservation Science, Royal Society for the Protection of Birds, The Lodge, Sandy, Bedfordshire, United Kingdom

Piotr Marczakiewicz

Affiliations Ogólnopolskie Towarzystwo Ochrony Ptaków, Marki, Poland, Biebrzański Park Narodowy, Osowiec Twierdza 8, Goniądz, Poland

Lars Lachmann

Affiliation RSPB Centre for Conservation Science, Royal Society for the Protection of Birds, The Lodge, Sandy, Bedfordshire, United Kingdom

Grzegorz Grzywaczewski

Affiliation University of Life Sciences, Department of Zoology, Animal Ecology and Wildlife Management, Lublin, Poland

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: SO LL PM. Performed the experiments: GG PM. Analyzed the data: SO. Contributed reagents/materials/analysis tools: SO. Wrote the paper: SO. Obtained permission and recruited fieldworker: PM GG. Obtained funding and managed project: LL. Commented on manuscript: LL PM GG.