At first glance, the Vogelkop Gardener bowerbird is pretty boring. Its drab olive-brown plumage makes it hard to spot against the dirt on which it lives. However, a closer look reveals that this otherwise dull bird has a secret: the males build some of the most elaborate, aesthetically-pleasing objects of any bird.

Bowers are decorated structures that the males build to woo females. In some places they're tall towers made of sticks resting upon a round mat of dead black moss, decorated with snail shells, acorns, and stones. In other places, they're woven towers built upon a platform of green moss, adorned with fruits, flowers, and severed butterfly wings. Individual Vogelkop bowerbirds have their own tastes, preferring certain colours to others. The males place each item in their bowers with great precision; if the objects are moved, the birds return them to the original arrangement.

"Decorating decisions are not automatic but involved trials and 'changes of mind,'" wrote UCLA physiologist Jared Diamond, one of the first researchers to intensively study the birds' complex bowers. Diamond discovered that bower building was not innate, at least not entirely. The younger birds had to learn how to build the best bowers, either through trial and error, or by watching more experienced birds, or both.