英语时差：北美燕八哥

Brown-headed cowbirds are robin-sized black birds whose range covers most of North America. From a people’s point of view cowbirds are what we might call deadbeat parents. Cowbirds lay their eggs in the nests of other bird species, and the cowbird nestlings are raised by the foster parents. Since the cowbirds spend their formative months with birds of an entirely different species which has separate habits, songs, etc., “How does a cowbird know it’s a cowbird?” A good question, since singing the right songs and making the right moves are essential to establishing territory and attracting mates, it’s vital that one do these things right. One would think that the cowbird’s behavior would be “hardwired”, that it would just know what it is. But work done by Meredith West and her colleagues has shown that this is not the case.