Foraging, predation hazard and patch use in grey squirrels

Grey squirrels, Sciurus carolinensis, responded to the difference in food quantity, so that aggregation sizes matched predictions based on relative patch size, as well as those based on feeding rates within patches, which exerted a significant effect on the pattern of patch use.

Abstract

Two patches of food, one large and one small, were placed at equal distances from protective cover. Grey squirrels, Sciurus carolinensis, responded to the difference in food quantity, so that aggregation sizes matched predictions based on relative patch size, as well as those based on feeding rates within patches. The large patch was then moved farther from cover, where the probability of predation per unit foraging time should be greater. Aggregation sizes in the large patch decreased significantly, and overcrowding in the small patch resulted in reduced average feeding rates. The experiment was next repeated with the amount of food in each patch doubled. Increased distance to cover again resulted in decreased aggregation sizes in the larger patch, but average feeding rates did not decline in the small groups that were observed. Squirrels responded to relative, but not necessarily absolute, differences in food availability. When patches differed in both food availability and the hazard of predation, each attribute exerted a significant effect on the pattern of patch use.