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n avian culture, when it comes to courtship the most flamboyant man wins; women blend into the background. As breeding season approaches, males sport gaudy feathers and bright ornamentation. “A pattern seen in many bird families is to grow brightly colored ornamental feathers for courtship and breeding, and then to molt into a much drabber plumage for the nonbreeding period,” Hill explains. “After breeding, bill, eye and leg coloration often changes from colorful and striking to drab and inconspicuous.” One of the most spectacularly decorated male birds is the peacock, whose tailfeathers drove naturalist Charles Darwin to tears. Having just published On the Origin of Species By Means of Natural Selection, he didn’t understand how the peacock’s sensational tailfeathers contributed to the bird’s longevity; in fact, it seemed as though a peacock’s showiness would likely endanger the bird by drawing attention to it. Finally, the frustrated evolution theorist concluded that a male peacock’s gaudiness might have no purpose other than to make him irresistible to females. Darwin labeled the process “sexual selection”; his 19th-century colleagues thought he was nuts. “Humans were walking on the moon before most biologists began to take Darwin’s ideas about mate choice seri-
ously,” Hill says. Below: A dramatic “Sexual selection closeup of the blueacting through and-yellow macaw the cover of female choice fi- illustrates Auburn scientist Geofnally gained wide frey Hill’s new book. acceptance as a Each macaw’s striping is as unique as reasonable expla- pattern a human fingerprint. nation for orna- Right: Alumnus Matmental traits like thew Shawkey ’05 and colleagues have figured bird coloration out the plumage color when a series of of prehistoric birds. behavioral studies confirmed that female fish and birds of some ornamented species prefer more colorful males.” Much of Hill’s career has been spent studying female mate choice in the house finch, conducting experiments both in the wild and in captivity. “Females definitely find the redder males sexier,” he notes, adding that the rosy color likely arises from pigments in food—the redder the feathers, the better the diet; the better the diet, the more likely the male finch will be able to provide for his wife and children. “Mate choice is serious business for female birds,” Hill says. “The male that a female selects to sire her young and be her partner during nesting can have a huge impact on her reproductive success. For some birds, choosing a mate is a bigger decision than where to nest, when to nest or how many eggs to lay.” Ornithologists have identified three “payoffs” for female birds that choose a brightly colored mate: food, protection and good genes. “It’s called the ‘sexy son’ hypothesis,” Hill explains. “If colorful plumage makes offspring more attractive as mates when they mature, then young sired by attractive males will inherit the attractive appearance and will be more successful at gaining mates.” Sound familiar?
Girl finch attends her babies in a nice nest in some dense bushes along the Auburn quad and awaits her man, who is off trying to find them all something to eat. She assesses her kingdom, noticing that her human watcher has left for the day, along with the others. She twitches, flutters and turns again to her chicks. Maybe the humans have their own mouths to feed.
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