And you thought match.com was a lot of work. Male bowerbirds are well known for building elaborate love dens, then performing outlandish dances in hopes of getting a date. New research suggests these birds might have something in common with your average online dater--they're trying to cast as wide a net as possible. Various aspects of the complex courtship behaviors appeal to females of different ages.
Males of the forest-dwelling satin bowerbird, Ptilonorhynchus violaceus, build their bachelor pads on the ground, weaving together sticks into baskets with wide, flat porches. To attract females, the males adorn their porches with shiny blue parrot feathers and other gewgaws. Females judge a suitor's decorating prowess by checking out his bower when he's away, and later, by watching their favorite bachelors perform courtship displays for her eyes only. But not all females are looking for the same thing, a team of researchers led by Seth Coleman of the University of Maryland, College Park, reports in the 15 April issue of Nature.
The researchers tested the preferences of female satin bowerbirds in New South Wales, Australia, over the course of more than 2 years. After upgrading 30 bowers with blue tiles and strands of blue plastic, they set up automated cameras to check how females reacted. Young females, the research showed, usually chose males with bluer bowers. Older females, however, only responded favorably to over-decorated dens on the first visit, when males weren't around to be judged for themselves. The rest of the time, older females were more swayed by a good song and dance. In fact, the more intense the display, the more attracted older females were. Coleman suggests that male strutting and buzzing may scare off young females but the older, wiser females view these performances with a critical eye.
The study is a creative and “experimentally well-demonstrated example of why complex displays might exist,” says evolutionary biologist Mike Ryan of the University of Texas, Austin. Different females like different things, he says.