Ever wished you were a squirrel? I did.
Ever forgotten where you left your homework, notes, or things you cannot live without –mobile phone and spectacles? Now imagine you had stored these items underground, over kilometers of land; what would your retrieval rate be weeks, or even months, later? This may appear to humans a far-fetched scenario, but for grey squirrels (Sciurus carolinensis), caching* and retrieving nuts, their vital food source, is a common activity, especially during cold weather, when food is less abundant.
‘Squirrels have been criticized for hiding nuts in various places for future use and then forgetting the places’ (Cuppy 1949). However, it has been observed that squirrels are far from forgetful and that the occurrence of squirrels digging up a nut to consume is often not by chance but a purposeful act of retrieval.
In an experiment by Jacobs and Liman (1990), “grey squirrels retrieved significantly more nuts from their own (cache) sites than from sites used by other squirrels” after up to 12 days. While grey squirrels can locate a cache by the odour of its contents (Thompson & Thompson 1980), since it does unearth nuts other than its own, odour plays a second role to memory. It was curiously noted that the squirrels often headed straight for their own cache sites, even by-passing nuts closer to them but hidden by other squirrels. Given also that the site locations often overlap or are adjacent to each other, it was concluded squirrels do indeed remember where they hid their food. This is backed by a larger study done on western fox squirrels (Sciurus niger rufivente) whereby fox squirrels retrieved 99 percent of the nuts they buried and nuts cached by the experimenter were overlooked (Cahalane 1942).
Being rather absentminded, I am jealous of squirrels’ memory! If I ever misplace something again, perhaps it could help to imagine myself as a cute little squirrel. For the devastatingly forgetful though, consider investing in a furry friend –just remember to keep your snacks locked up!
*caching is the act of storing away in hiding or for future use.
References & Acknowledgements
Image: Almond snack on a porch by liquidnight
Cahalane, V.H., 1942. Caching and Recovery of Food by the Western Fox Squirrel. The Journal of Wildlife Management, Vol. 6, No. 4: pp. 338-352. Also available at http://www.jstor.org/stable/3795921.
Kamil, A.C., Gould, K.L., 2008. Memory in Food Caching Animals. Learning and Memory: A Comprehensive Reference, Vol. 1, pp. 419–439. Also available at http://dx.doi.org.libproxy1.nus.edu.sg/10.1016/B978-012370509-9.00062-0.
Jacobs, L.F., Liman, E.R., 1991. Grey squirrels remember the locations of buried nuts. Animal Behaviour, Vol. 41, Issue 1: pp. 103-110. Also available at http://dx.doi.org.libproxy1.nus.edu.sg/10.1016/S0003-3472(05)80506-8.