The cuckoo is more than a hooting bird that pops out of an ornate clock. It is a real bird, and it is a brood parasite. The cuckoo invades the nest of smaller species of birds, laying its own eggs so that those poor new bird parents now sit atop large eggs. Eventually, these eggs will hatch, and the baby cuckoos will take food meant for the other birds’ young. It’s a clever bit of trickery and laziness on the part of the cuckoo: someone else does all the work.