Birds arrange eggs in their nests to better detect imposters

Most birds build their own nests and incubate their own eggs. However, some birds like the cuckoo have managed to get around this inconvenience by simply laying their eggs in the nests of other species and letting someone else do the hard work of keeping the eggs warm and protected until the chick hatches. The ‘host’ (the poor sucker who ends up taking care of the other birds’ eggs) does everything they can to try and make sure the eggs that they’re sitting on are just their own. On the other hand, the ‘brood parasite’ (the freeloader bird that just lays in the nests of others) does everything they can to make their eggs indiscernible from the eggs of their host.

Of course, neither host nor parasite is trying to achieve anything consciously; their eggs are shaped by evolution and there is natural selection both on the brood parasite to produce eggs that are very similar to the host they are attempting to parasitize, and on the host to be extra discerning in telling which eggs are their own.

Lees meer: Scientific American