Interspecific Differences in Avian Feeding Behavior and the Evolution of Batesian Mimicry

Abstract

AbstractThis paper describes an experiment on interspecific differences in the response of bird predators to an artificial Batesian mimic/model complex. Black-capped chickadees (Parus atricapillus) and white-crowned sparrows (Zonotrichia leucophrys) were offered a series of 24 pairs of models and mimics after an initial presentation of the emetic model (a 1/2 mealworm adulterated with quinine sulphate and with a black dot painted on it). Chickadees attacked many mimics (unaltered 1/2 mealworms) and a few models. White-crowned sparrows attacked few mimics and almost no models. Differences between species in the manner of preparing mealworms for consumption may have contributed to the interspecific differences in the treatment of the series of model/mimic pairs. Perhaps more importantly, the chickadees, as opportunistic feeders dependent on a wide variety of prey, may possess special tolerance to noxious stimuli. The sparrows, conservative feeders with a more limited range of prey species, need not possess this tolerance in order to exploit their niche fully. Interspecific differences in feeding behavior could contribute to the origin and perfection of Batesian mimicry.