Abstract
If food pilferage has been a reliable selection pressure on food caching animals, those animals should have evolved the ability to protect their caches from pilferers. Evidence that animals protect their caches would support the argument that pilferage has been an important adaptive challenge. We observed naturally caching Eastern grey squirrels (Sciurus carolinensis) in order to determine whether they used any evasive tactics in order to deter conspecific and heterospecific pilferage. We found that grey squirrels used evasive tactics when they had a conspecific audience, but not when they had a heterospecific (corvid) audience. When other squirrels were present, grey squirrels spaced their caches farther apart and preferentially cached when oriented with their backs to other squirrels, but no such effect was found when birds were present. Our data provide the first evidence that caching mammals are sensitive to the risk of pilferage posed by an audience of conspecifics, and that they utilise evasive tactics that should help to minimise cache loss. We discuss our results in relation to recent theory of reciprocal pilferage and compare them to behaviours shown by caching birds.
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Acknowledgements
We would like to thank Stephen Lea, Nicola Clayton and Stephen Vander Wall for helpful comments on an earlier draft of the manuscript, and Stephen Lea also for his statistical advice. We thank Paul Cline and Finola Ingham for assistance with marking the squirrels. The research was partly funded by a grant from the University of Exeter URF fund. Squirrels were live-trapped and released under DEFRA Non-Native Species Release Licence WCA\02\11.
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Leaver, L.A., Hopewell, L., Caldwell, C. et al. Audience effects on food caching in grey squirrels (Sciurus carolinensis): evidence for pilferage avoidance strategies. Anim Cogn 10, 23–27 (2007). https://doi.org/10.1007/s10071-006-0026-7
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DOI: https://doi.org/10.1007/s10071-006-0026-7