Differences in food hoarding behaviour in two species of ground squirrels Spermophilus tridecemlineatus and S. spilosoma

Abstract

Storing food items is considered an alternative to fat storage in many species of ground squirrels. In a comparative study in the laboratory, we hypothesized that two closely-related ground squirrels, Spermophilus tridecemlineatus and S. spilosoma (subgenus Ictidomys, Rodentia Sciuridae), could hoard food and that the highest proportion of individuals displaying hoarding should be observed in the species with the greatest changes in body masses over both active and hibernation periods. Moreover, food hoarding is often displayed when a resource is temporarily available. Hoarding should be more frequent when the feeding conditions change and stable feeding conditions over several tests should decrease hoarding. Contrary to the predictions, S. spilosoma rarely hoarded food, whereas many S. tridecemlineatus did it. As predicted, the number of animals hoarding food was maximum for new feeding conditions and decreased with repetitive trials.