Experiments and observations of prothonotary warblers indicate a lack of adaptive responses to brood parasitism

摘要: It has been suggested that prothonotary warblers, Protonotaria citrea, respond adaptively to brood parasitism by brown-headed cowbirds, Molothrus ater, even though they lack historical habitat and range overlap with cowbirds. I studied behaviours functioning as potential defences against in the warbler, a cavity-nesting host species. Opening sizes preferred warblers were not small enough exclude parasitized heavily nests larger openings. Male female always away from their before sunrise when cowbirds laid eggs nests. Prothonotary infrequently (6% of 560 nests) deserted during egg-laying period, but frequently (56% 151 warbler her first egg. also 60–70% where cowbird egg, egg or die experimentally added laying. However, experimental addition one these three objects period did elicit desertion. The desertion was affected nest site availability reported elsewhere literature. This response may be an example evolutionary lag, because it is likely have only recently exposed widespread parasitism, accept at high cost own reproductive success.  2003 Published Elsevier Science Ltd on behalf Association for Study Animal Behaviour.