AT LAST, BIOLOGY THAT MAKES SENSE

From: Birds don't mess with the cowbird mafia (Randolph E. Schmid, Globe and Mail, March 6th, 2007)

People have long wondered how cowbirds can get away with leaving their eggs in the nests of other species, who then raise the baby cowbirds. Why don't the hosts just toss the strange eggs out?

Now researchers seem to have an answer -- if the host birds reject the strange eggs, the cowbirds come back and trash the place.