Male bowerbirds famously woo females by fashioning elaborate bowers—not nests but U-shaped showplaces with parallel walls of twigs. There the males prance and noisily serenade the females.
This spectacular courtship ritual during the November and December mating season has long attracted ornithologists to the species formally known as satin bowerbirds, native to Australia.
New research, however, reveals that the ritual may be even more complex and subtle than previously recognized; male satin bowerbirds mimic the calls of other bird species to attract a mate.
Understanding the dynamic of bowerbird courtship helps scientists understand sexual selection—a hot topic since Charles Darwin first proposed it in 1871. Darwin observed that females were attracted to "fancy males" who displayed traits that appealed to the eye and ear—purely, he hypothesized, for the purpose of sexual attraction.
Once the males have built their bowers, they perch in them, squawk and whistle.
"The males are basically saying, I'm here in my bower, I'm available and I'm ready for assessment," says Seth Coleman, a doctoral candidate in behavioral ecology at the University of Maryland in College Park who has led a three-year bowerbird research project in the Australian bush, funded by the National Science Foundation.
When a female enters a bower, the male ruffles his feathers, stretches his wings and makes loud buzzing sounds as he struts and runs about. Meanwhile the female also is apparently checking out his architectural talent—the bower's symmetry and decoration (females are partial to anything blue like a feather, a bottle cap or a shell).
Mimicking Five Species
Previous studies have shown that females are less likely to choose a male in an unkempt bower.
But architecture isn't everything. Last year, Gail Patricelli, a former colleague and lab partner of Coleman who is now with the Cornell Lab of Ornithology in Ithaca, N.Y., discovered that successful males could interpret the females' body language and modify their courtship moves accordingly.
After the male's raucous vocalizations, he makes a more intimate appeal, coming almost beak to beak with the female and softly mimicking five other Australian birds: the kookaburra, the Lewin's honeyeater, the sulfur-crested cockatoo, a Torresian crow and a yellow tailed black cockatoo.
If the mimicry impresses the female, mating proceeds apace. Otherwise she flies to the next bower.
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