Distracted foragers: competitors impair foraging efficiency, accuracy and speed for eastern grey squirrels

Abstract

Social foraging can be beneficial, but it can also disrupt optimal foraging strategies. Animals possess limited capacity for attention allocation and distractions may impact their rates of food acquisition. Attention to conspecific food competitors can prevent kleptoparasitism but likely affects food intake in multiple ways. We used two field experiments to assess the impact of nearby competitors on urban eastern grey squirrel, Sciurus carolinensis, foraging in a forest setting on the University of Toronto Scarborough campus. We used a tube apparatus in the first experiment to examine foraging efficiency and a tipping container apparatus in the second experiment to examine foraging speed (handling time) and accuracy. Competing squirrels within 1 m or having just been involved in chasing or aggressive physical contact with competitors led to decreases in foraging efficiency, speed and accuracy. Competitors within 5 m of focal squirrels did not impact foraging measures. Over the course of the experiments, squirrels adapted to solving foraging apparatuses in the presence of competitor(s) and improved their efficiency and accuracy but not their speed. Vigilance rates were greater for squirrels that had competitors nearby; thus, decreases in foraging efficiency, accuracy and speed seemed to be caused by the need to allocate attention to conspecifics. These experiments show that social foraging impairs optimal food acquisition for individual eastern grey squirrels.