Caching decisions by grey squirrels: a test of the handling time and perishability hypotheses

This study was designed to investigate the relative effects of seed perishability and handling time on the caching preferences of grey squirrels,Sciurus carolinensis, and to test the predictions for caching behaviour that follow from these two hypotheses. Free-ranging squirrels were presented with acorns from two oak subgenera,ErythrobalanusandLeucobalanus, that vary in perishability (due to germination schedules) and handling time (due to acorn size). In six separate caching experiments, individual squirrels were sequentially presented with two acorn types, so that each paired treatment varied in handling time and/or perishability. Caching responses were recorded for each acorn, along with eating and caching times. Squirrels consistently consumed acorns of high perishability and cached acorns of low perishability, without regard to handling time. This result suggests that the perishability of seeds exerts a greater influence than handling time on the grey squirrel's decision to cache acorns.