GROUP CHOICE - COMPETITION, TRAVEL, AND THE IDEAL FREE DISTRIBUTION

If a group of foragers distributes among resource patches according to the ideal free distribution, the relative number of foragers in each patch should match the relative amount of resource obtained there, unl ess deviations arise from factors such as incomplete information or in terforager interference. In analogy to individual choice, such effects may produce undermatching-group distribution falling short of resourc e distribution-or overmatching-group distribution overshooting resourc e distribution. In the present experiments, a flock of about 30 pigeon s distributed between two patches with continuous inputs of green peas . Competition was varied by changing the size or extent of the patches . When the patches were areas or troughs, some undermatching occurred. When the patches were small bowls, strong undermatching occurred. Whe n travel was required to switch patches, undermatching decreased sligh tly. A visual barrier that prevented pigeons from seeing one patch fro m the other had no effect. Overall rate of food delivery, varied over a wide range, had no effect. It appeared that the mechanism of flock d istribution depended on comparisons between patches that were successi ve rather than simultaneous. Although most pigeons participated in the experiments, and different pigeons participated to different extents, individual pigeons tended to be consistent in the extent of participa tion from session to session, suggesting the possibility that particip ation might reflect competitive ability. Examination of the preference s and switching of individual pigeons revealed no consistency within o r across individuals. It appeared that the flock's distribution was a truly emergent phenomenon, in the sense that results at the level of t he flock in no way paralleled behavior at the level of the individual.