"That's the ultimate test," says Brett Benz, the University of Kansas ornithologist who named Donald after the real estate magnate. "OK, so he has the tallest tower around. Let's see if he can pull down a Mary." In the local pidgin, "Mary" is a term for the fairer sex.
To woo females, the males of 17 of the 20 known species of bowerbirds build structures—often resembling an arbor, or bower, with an artfully decorated platform. Benz has measured all the Macgregor's males' bowers he's found in this forest, so he can speak with authority about Donald's achievement. Benz also knows a great deal about what Donald and other males do at their bowers, since he has video cameras set up in blinds recording the birds' every move, including their matings.
Scientists are drawn to bowerbirds because they clearly show the power of sexual selection, the evolutionary force that Charles Darwin defined to explain conspicuous male traits such as song, bright colors, and horns. In most animal species, Darwin noted, females do the choosing—basing their decision on the ornamentation and ostentation males use to attract them. Because most bowerbirds are polygynous, meaning one male is the mate of more than one female, and these males build decorative bowers, they make excellent species for testing this idea. Males don't help the female build a nest, incubate the eggs, or raise the chicks—all they give her are their genes. The females are thus very choosy about which male they pick.
People also study bowerbirds because, well, because they're surprisingly similar to people. Indeed, evolutionary biologist Jared Diamond has called them "the most intriguingly human of birds." These are birds that can build a hut that looks like a doll's house; they can arrange flowers, leaves, and mushrooms in such an artistic manner you'd be forgiven for thinking that Matisse was about to set up his easel; some can sing simultaneously both the male and female parts of another species' duet, and others easily imitate the raucous laugh of a kookaburra or the roar of a chain saw. Plus, they all dance. And about Donald's pile of beetles: He killed them solely for the purpose of decorating. Humans are the only other species known to use animals in this way.