Preliminary Experiments on the Foraging of Closely Related Species of Birds

The foraging and interactions of three species of sparrows were studied. Both in the wild and in experiments, Zonotrichia melodia and Z. georgiana foraged similarly and with relatively little interaction. Z. melodia was always dominant to Z. georgiana. A greater degree of interaction occurred between Z. melodia and Z. albicollis. These two species foraged differently, Z. melodia spending more time feeding in the grass than Z. albicollis. The degree of differences in foraging between them remained constant from the first to the second experiment, even though both species fed more in the grass in the latter than in the former. In neither experiment was the difference in foraging caused by interactions between the two species in the experiments. It is suggested that interspecific differences in foraging and interaction are related to the need for avoiding competition.