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Get a taste of what awaits you in print from this compelling excerpt.
It's a blustery spring day in the Australian outback, the kind that makes you think rain must be on the way, although there hasn't been a drop in months, and the ground is brown and parched. In some animals, frogs for instance, a dry spring can slow down or stop altogether the normal, romantic inclinations that come this time of year. But the lack of rain hasn't deterred the male spotted bowerbirds.
Under old peppertrees, thornbushes, and stands of oleanders, they've built elaborate U-shaped arenas of dried grasses, 12 to 14 inches (30 to 35 centimeters) high and 12 to 20 inches (30 to 50 centimeters) long. They've decorated them with piles of sun-bleached sheep vertebrae, shiny aluminum foil, pop-tops from beer cans, shards of broken windshield glass, and little strips of red and blue plastic. The fanciest bowers feature special, seductive tidbits: a silver fork, the shoe token from a Monopoly game, old gun shell casings, red, blue, and purple glass of the deepest hues. The birds have arranged their treasures with an eye to the light—how does that bone pile look when the morning sun hits it?—and to their symmetry: silver metal hoops of unknown origin, for example, placed at equal distances from opposite ends of the bower.
Now a male can do little more than watch and wait. If he's built a good bower, then he'll succeed in life's ultimate contest and win the top prize: a female who chooses him as a mate.
"That's really what it comes down to," says Gerry Borgia, an evolutionary biologist who has studied the mating behaviors of bowerbirds for 23 years. "So you wonder sometimes when you see poorly built bowers," he says, pointing to one in disarray. "You want to say to the guy: 'Hey! This is about your reproductive success! Get moving! Straighten those straws! Find some more bones! Why be a C student?' "
Borgia, a hefty, middle-aged man with a broad, gap-toothed smile, bends over a video camera he's placed a short distance from the bower and changes the tape. He's stationed similar cameras with microphones at 22 bowers scattered across the sheep and cattle stations near the sleepy town of Nyngan. The cameras are equipped with motion-detection sensors and record whatever the male birds—or their female visitors—do within the bowers. Later, in his University of Maryland lab, Borgia's students will review the tapes, picking out the ones that show what male bowerbirds might dream about: a female entering the straw bower, watching the male perform and sing for her, and, if she is well pleased, accepting him as a mate. Borgia isn't sentimental about this latter event, referring to it simply as a "cop"—short for copulation.
"You watch enough of these cops, and you begin to get a feel for why the female chooses one male and not another," he explains. "It's my guess that this guy isn't going to do well. I mean, that's pathetic," he says, waving his hand at the bird's puny pile of vertebrae. "And the thing is, he took over this site from an older male who died, but who had a great bower with lots of bones. And they're still here! This new guy just hasn't made the effort to move them to his bower."
Get the whole story in the pages of National Geographic magazine.
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