Behavioral Ecology Advance Access originally published online on July 30, 2008
Behavioral Ecology 2008 19(6):1143-1149; doi:10.1093/beheco/arn095
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Effects of competition and food availability on travel time in scatter-hoarding gray squirrels (Sciurus carolinensis)
School of Psychology, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter, Devon, EX4 4QG, UK
Address correspondence to L.J. Hopewell. E-mail: l.j.hopewell{at}exeter.ac.uk.
| Abstract |
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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.
Key words: food competition, gray squirrels (Sciurus carolinensis), scatter hoarding.
Received 14 March 2008; revised 26 June 2008; accepted 2 July 2008.