About the Authors

Zanna Clay

Affiliations School of Psychology, University of St Andrews, St Andrews, Scotland, United Kingdom, Twycross Zoo, Twycross, Atherstone, United Kingdom

Klaus Zuberbühler

kz3@st-andrews.ac.uk

Affiliation School of Psychology, University of St Andrews, St Andrews, Scotland, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: KZ ZC. Performed the experiments: ZC. Analyzed the data: ZC. Contributed reagents/materials/analysis tools: KZ. Wrote the paper: KZ ZC.