But the mimicry of leaf insects, as cool as it may be, is simple stuff compared to what’s evolved in other species. The leaf insect mimics just one other living thing: a leaf. But there’s another kind of animal that can mimic two different species, and for entirely different effects.
That animal is the cuckoo. Instead of building their own nests, female cuckoos slip into the nests of other birds and lay their own eggs. They’re parasites, although not of the sort we may be familiar with, like a tapeworm that glides into our gut and exploits us from within. Cuckoos exploit the parental care of their hosts.
When a host bird returns after a visit from a cuckoo, it may recognize an alien egg in its brood and knock it out of the nest. But often it won’t. That’s because the cuckoo is very good at mimicking its host species. The shells of their eggs often closely match those of the species they exploit. Unable to tell the difference between the parasitic eggs and their own, the host birds will care for them all.