Foraging Behavior of Urban Birds: Are Human Commensals Less Sensitive to Predation Risk than their Nonurban Counterparts

We hypothesized that the foraging behavior of urban birds would be less sensitive to variation in the cost of predation than that of nonurban bird species. We predicted that food-patch utilization by House Sparrows (Passer domesticus), a widespread human commensal, would be less sensitive to variation in predation risk than that of Spanish Sparrows (P. hispaniolensis), its nonurban counterpart. We applied the giving-up density (GUD) method to quantify patch use behavior of the two species with respect to distance from shelter. Our results indicated that Spanish Sparrows perceived a steep gradient of increased predation cost with increasing distance from shelter, while House Sparrows seemed indifferent to distance from shelter. These results support the hypothesis that the cost of predation has less effect on the foraging behavior of urban than nonurban birds, although alternative explanations include differences between species in the degree of neophobia, or variations in their ability to assess predation risk.