On a quiet side road through a wooded area, I played a tape of a bird I was looking for, a Cerulean Warbler, to refresh my memory of their song. As it played, I was amused to see a female Brown-headed Cowbird land on the road and begin to look intently about. The Cowbird is a brood parasite which lays it’s eggs in the nest of other birds to raise its young. It seemed that this female was interested in seeing if the Cerulean Warbler pair it thought it heard, could be its next victim.
Host species have a number of ways of handling these introductions, sometimes ejecting the egg or Cowbird chick, and sometimes burying it in the nest material. Others simply desert the nest and start over.
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