In Australia, not only do the hosts break the rules, so do the cuckoo chicks. “Because of this good recognition ability in hosts, cuckoo chicks have evolved wonderful mimicry of host young, either in appearance or in begging calls, which you don’t get anywhere else.” The bronze-cuckoos, which target fairy-wrens, thornbills, and gerygones, she says, “have evolved these fantastically matching chicks that mimic the size, the skin color, the down color, even the mouth color of the host species.”
