CODY - A researcher studying sage grouse in Wyoming has developed an innovative method for gaining a bird's-eye view of their elaborate courtship displays.
The "fembot" is part robot, part decoy and part model railroad car, but the sum of those parts adds up to a system that lets Gail Patricelli capture a close-up view of male sage grouse mating overtures from the female bird's perspective.
"The sage grouse is the North American version of the peacock, because of their bizarre and elaborate traits," said Patricelli, a professor of evolution and ecology at the University of California at Davis.
Davis has been studying sage grouse near Lander and Hudson to learn more about how social skills of male sage grouse are related to success in mating.
Some birds have evolved specialized traits that help them survive, like a hawk's hooked beak and sharp talons. Male sage grouse have evolved complex and bizarre anatomy and behavior to help attract mates, a process called sexual selection.
"They make amazing and very unusual sounds, and the males puff up and strut around while the females comparison-shop for a mate," she said.
"Their courtship is not just about having the flashiest traits. It's also about interacting appropriately. The males need to know how and when to approach the females. I've been interested in the degree to which sexual selection drives the evolution of those traits," Patricelli said.
To study that, she built a small robot that resembles a female sage grouse, with a video camera and microphone hidden inside. Mounted on a model railcar chassis, the remote-controlled fembot is sent out from a blind on tracks to the center of a lek, or mating grounds.
Patricelli can rotate the fembot and move it along the track. She uses it as a kind of "benchmark female" that always behaves the same way, reducing the study of the mating ritual to a focus on what the males do, and why some are so successful.
"If you just watch the guys from a distance, they look a lot alike. But it turns out that one or two guys are doing almost all of the mating, and the females are almost unanimous in who they like," Patricelli said.
As with the human species, male social skills are often critical to attracting the highly selective females.
"Anyone who has observed any courtship in any species, including our own, knows these things go on. There's all sorts of dancing around, and some individual animals are better at it than others," she said.
At some leks, where up to 60 birds are gathered, Patricelli has observed one male mate 43 times, while a handful of other males may mate between one and seven times, and most of the rest fail entirely.
"So, the evolutionary payoff to being that guy who mates 43 times is huge," she said, adding that the Casanova of each lek is usually the male offering the best song-and-dance routine.
"The amount of time they spend on the lek and the rate at which they display are important, so they have to show up and work hard," Patricelli said.
"But part of it is also the quality of the sound that the female likes," she said, adding that the timing and volume of how the males whistle and pop is important, as well as how males position themselves so that they can best be heard.
"The successful males keep it toned down as the female is far away. But as they get closer, he ratchets it up, and also really struts. And as he is really close, he is able to put on fast displays with good quality and good-quantity signals," she said.
"The unsuccessful males blast away at a mediocre level all the time, and if they do increase their rate, it typically lowers the quality," she said.
As sage grouse numbers continue to dwindle in many places outside of Wyoming, researchers are seeking to learn more about how the birds reproduce. Patricelli and others are studying whether noise from energy development or other disturbances may interfere with sage grouse mating.
Patricelli said the fembot is a useful research tool because "you can literally get inside the head of a female and learn what she sees or hears."
Contact Ruffin Prevost at firstname.lastname@example.org or 307-527-7250.