for National Geographic News
As a woman matures, so does her taste in men. What attracts her at 20 will most likely differ when she's 30. Female bowerbirds, it seems, share these age-specific preferences when it comes to choosing mates.
A new study finds that a young, inexperienced, female bowerbird judges a male by the manner in which he decorates his bachelor pad. Once she's aged and mated a few times, this affinity for a swanky domicile fades, and she then relies on courtship routinea vigorous song and danceto select the most worthy suitor.
This research suggests that feminine taste, throughout the animal kingdom, may be more complicated than anyone thought.
The process through which a female satin bowerbird (Ptilonorhynchus violaceus) chooses her mate illuminates a relatively unexplored area of sexual selectiona theory that Darwin first proposed in 1871.
Darwin noticed that females are attracted to "fancy males" with lavish traits that appealed to the ear and eye: bright feathers, long tails, intricate songs, and complex dances. But little research has investigated how the female weighs these fancy traits against one another.
"Not all females find the same trait attractive," said Seth Coleman, a doctoral candidate in behavioral ecology at the University of Maryland in College Park, and co-author of a report that appears in the April 15 issue of the science journal Nature. "We think males have evolved complex mating rituals and a diverse collection of [fancy] traits to appeal to as many females as possible."
"The best males will have it all," said Coleman, who conducted a three-year satin bowerbird study in the Australian bush. The top male bowerbirds have what might be called artistic talent and vigorous courtship routines.
The Courtship DanceThe Buzz-Wing-Flip
Until recently people assumed that all females of a particular species preferred the same traits. We now know, based on Coleman's work, this is simply not true, said Stephen Nowicki, an evolutionary ecologist at Duke University in Durham, North Carolina. "This is a significant advance in the study of sexual selection."
Male bowerbirds are famous for their courtship rituals. They carefully decorate their bowersU-shaped platforms built from twigs and grasswith strictly blue objects like berries and flowers, and even bottle caps and string, to attract prospective mates.
When a female pays a visit, she crouches in the bower and lets the male strut his stuff. He embarks on a frenetic physical display dubbed the buzz-wing-flipan elaborate dance during which he fluffs up his feathers, produces buzzing vocalizations, and runs back and forth. The male performs this maniacal dance four times. Once he's finished, the female is off to the next bower, reserving judgment until she's sampled more performances.
Coleman and former lab mate Gail Patricelli, now a postdoctoral researcher at Cornell University in Ithaca, New York, suspected that young females are frequently startled by the males' spirited song and dance. The scientists classify the young females as "first years" and "second years" (those with no prior mating experience or just a single mating, respectively.)
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