Central Place Foraging in the Whinchat, Saxicola Rubetra

In many species of animals, foraging individuals depart from and return to a central place. In a test of a model for such central place foragers, the time spent searching at different distances from the nest was recorded in an insect—feeding bird, the Whinchat (Saxicola rubetra), with and without additional food distributed over the foraging area. The following predictions were realized: (a) the search effort per unit area decreased with increasing distance from the central place; (b) with higher initial food density, the birds searched more near the nest, and less farther away; (c) the foraging area decreased when food was added; (d) the birds took more of the available food near the nest than far from it. Further, Whinchats apparently searched for food where it was cheapest for the moment. Rapid adaptation to increased food density indicates that foraging behavior in Whinchats is under strong selection for efficiency.