Giving a friend a tour of Otterbein University recently, my wife and I guided her into its Science Center, mostly so I could re-visit its plexiglass aviary of parakeets just off the lobby. A subject of study by faculty and students, the birds, of the sort sold in countless pet shops, are native to Australia and are properly called budgerigars. Otterbein’s dozen budgies flit about in an array of colors and patterns: traditional greens, spritely blues, luminescent yellows.
“These birds all look different,” I said to our guest. “But all of them have something in common. Can you see it?”
A mathematician, she accepted this empirical challenge and circled the aviary. The birds took scant notice, accustomed to visitors. After she gave up, I said, “They’re all males.” The only giveaway is that, in the traditional patterns, males have a vivid blue cere, a patch of flesh, above their beaks.
Thus the chance to explain that Otterbein academics have duplicated a fraternity house—because a female-only budgie flock would fight. (And surely all hell would break loose if the academics had mixed males and females.)
“But why do they make that noise?” she asked me. “What are they saying?”
We listened to the birds’ chortling—an endless, repetitious but pleasing boy chorus. Why indeed? A traditional survival-of-the-fittest answer: they’re claiming territory. A prelude to war. But surely the best answer—and equally Charles Darwin’s—is: because female parakeets like the sound. Furthermore, they’re favoring males who are sociable enough to flock together to produce such background sound for them to enjoy.
The latter answer isn’t my Romantic notion but arrives courtesy of a remarkable new book, The Evolution of Beauty: How Darwin’s Forgotten Theory of Mate Choice Shapes the Animal World—and Us.