Leaver Lisa A, Hopewell Lucy, Caldwell Christine, Mallarky Lesley
School of Psychology, University of Exeter, Exeter, EX4 4QG, UK.
Anim Cogn. 2007 Jan;10(1):23-7. doi: 10.1007/s10071-006-0026-7. Epub 2006 Jun 21.
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.
如果食物盗窃行为一直是对食物贮藏动物的一种可靠选择压力，那么这些动物应该已经进化出保护其贮藏物不被盗窃者偷走的能力。动物保护其贮藏物的证据将支持这样一种观点，即盗窃行为是一个重要的适应性挑战。我们观察了自然贮藏食物的东部灰松鼠（Sciurus carolinensis），以确定它们是否采用任何规避策略来防止同种和异种动物的盗窃行为。我们发现，当有同种动物在场时，灰松鼠会采用规避策略，但当有异种动物（鸦科动物）在场时则不会。当有其他松鼠在场时，灰松鼠会将它们的贮藏点间隔得更远，并且在背向其他松鼠时优先进行贮藏，但当有鸟类在场时则没有发现这种效果。我们的数据首次证明，贮藏食物的哺乳动物对同种动物观众造成的盗窃风险很敏感，并且它们会采用规避策略，这应该有助于将贮藏物的损失降到最低。我们将我们的结果与最近的相互盗窃理论联系起来进行讨论，并将它们与贮藏食物的鸟类所表现出的行为进行比较。
