Effects of competition and food availability on travel time in scatter-hoarding gray squirrels (Sciurus carolinensis)

Abstract

Scatter-hoarding animals transport food away from its source before storing it to maximize the likelihood that the cache will survive for use at a later time. However, the more time animals spend transporting and storing the food the less time they have for food collection. Previous studies suggest that the time animals spend on caching depends to some extent on the availability of food and on the presence of conspecifics at the food source. We tested whether a scatter-hoarding mammal responds flexibly to conspecifics as competitors according to the availability of food or if they respond more directly to them as potential pilferers. We used multiple linear regression to model the time eastern gray squirrels (Sciurus carolinensis) took to return to nut patches of varying quality after collecting a nut for caching when they were alone and when conspecifics were present. The results provide the first evidence that scatter hoarders respond to conspecifics at a food source primarily as competitors rather than as potential pilferers; the squirrels increased the rate at which they returned to the nut patch when conspecifics were present rather than transport the nuts farther away to minimize the risk of pilferage. In contrast, and in line with previous studies, the squirrels responded to a reduction in the availability of food by increasing the distance at which they stored the food from the source. © The Author 2008. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.