Animal Cognition

, Volume 10, Issue 1, pp 23–27 | Cite as

Audience effects on food caching in grey squirrels (Sciurus carolinensis): evidence for pilferage avoidance strategies

  • Lisa A. Leaver
  • Lucy Hopewell
  • Christine Caldwell
  • Lesley Mallarky
Original Article


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.


Caching Deception Pilferage Grey squirrels Sciurus carolinensis 



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.


  1. Bednekoff PA, Balda RP (1996a) Social caching and observational spatial memory in pinyon jays. Behaviour 133:807–826Google Scholar
  2. Bednekoff PA, Balda RP (1996b) Observational spatial memory in Clark's nutcrackers and Mexican jays. Anim Behav 52:833–839CrossRefGoogle Scholar
  3. Bugnyar T, Kotrschal K (2002) Observational learning and the raiding of food caches in ravens, Corvus corax: is it ‘tactical’ deception? Anim Behav 64:185–195CrossRefGoogle Scholar
  4. Burnell KL, Tomback DF (1985) Stellar's jays steal gray jay caches: field and laboratory observations. Auk 102:417–419Google Scholar
  5. Clarkson K, Eden SF, Sutherland WJ, Houston AI (1986) Density dependence and magpie food hoarding. J Anim Ecol 55:111–121CrossRefGoogle Scholar
  6. Clayton NS, Griffiths DP, Emery NJ, Dickinson A (2001) Elements of episodic-like memory in animals. Philos Trans R Soc B 356:1483–1491CrossRefGoogle Scholar
  7. Dally JM, Emery NJ, Clayton NS (2004) Cache protection strategies by western scrub-jays (Aphelocoma californica): hiding food in the shade. Biol Lett 271:S387–S390CrossRefGoogle Scholar
  8. Dally JM, Emery NJ, Clayton NS (2005) Cache protection strategies by western scrub-jays Aphelocoma californica: implications for social cognition. Anim Behav 70:1251–1263CrossRefGoogle Scholar
  9. Daly M, Jacobs LF, Wilson MI, Behrends PR (1992) Scatter hoarding by kangaroo rats (Dipodomys merriami) and pilferage from their caches. Behav Ecol 3:102–111Google Scholar
  10. Duncan RS, Wenny DG, Spritzer MD, Whelan CJ (2002) Does human scent bias seed removal studies? Ecology 83:2630–2636CrossRefGoogle Scholar
  11. Emery NJ, Clayton NS (2001) Effects of experience and social context on prospective caching strategies by scrub jays. Nature 414:443–446PubMedCrossRefGoogle Scholar
  12. Emery NJ, Clayton NS (2004) The mentality of crows: convergent evolution of intelligence in corvids and apes. Science 306:1903–1907PubMedCrossRefGoogle Scholar
  13. Emery NJ, Dally JM, Clayton NS (2004) Western scrub-jays (Aphelocoma californica) use cognitive strategies to protect their caches from thieving conspecifics. Anim Cogn 7:37–43PubMedCrossRefGoogle Scholar
  14. Heinrich B, Pepper JW (1998) Influence of competitors on caching behaviour in common ravens, Corvus corax. Anim Behav 56:1083–1090PubMedCrossRefGoogle Scholar
  15. Kaas JH, Guillery RW, Allman JM (1972) Some principles of organization in the dorsal lateral geniculate nucleus. Brain Behav Evol 6:253–299PubMedGoogle Scholar
  16. Kraus B (1983) A test of the optimal-density model for seed scatterhoarding. Ecology 64:608–610CrossRefGoogle Scholar
  17. Lahti K, Rytkonen S (1996) Presence of conspecifics, time of day and age affect willow tit food hoarding. Anim Behav 52:631–636CrossRefGoogle Scholar
  18. Leaver L, Daly M (2001) Food caching and differential cache pilferage: a field study of co-existence of sympatric kangaroo rats and pocket mice. Oecologia 128:577–584CrossRefGoogle Scholar
  19. Lloyd HG (1983) Past and present distribution of red and grey squirrels. Mammal Rev 13:69–80Google Scholar
  20. Macdonald IMV (1995) Investigating grey squirrel spatial memory—with respect to cache recovery mechanisms. Ph.D. thesis, University of ExeterGoogle Scholar
  21. Smulders T (1998) A game theoretical model of the evolution of food hoarding: applications to the Paridae. Am Nat 151:356–366CrossRefPubMedGoogle Scholar
  22. Stapanian MA, Smith CC (1978) A model for seed scatterhoarding: coevolution of fox squirrels and black walnuts. Ecology 59:884–896CrossRefGoogle Scholar
  23. Stapanian MA, Smith CC (1984) Density-dependent survival of scatterhoarded nuts: an experimental approach. Ecology 65:1387–1396CrossRefGoogle Scholar
  24. Thompson DC, Thompson PS (1980) Food habits and caching behaviour of urban grey squirrels. Can J Zool 58:701–710CrossRefGoogle Scholar
  25. Vander Wall SB (1990) In: Food hoarding in animals. University of Chicago Press, ChicagoGoogle Scholar
  26. Vander Wall SB, Jenkins SH (2003) Reciprocal pilferage and the evolution of food-hoarding behavior. Behav Ecol 14:656–667CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Lisa A. Leaver
    • 1
  • Lucy Hopewell
    • 1
  • Christine Caldwell
    • 2
  • Lesley Mallarky
    • 1
  1. 1.School of PsychologyUniversity of ExeterExeterUK
  2. 2.Psychology DepartmentUniversity of StirlingStirlingUK

Personalised recommendations