Robotic sage grouse helps study lek activity

It’s time for the big dance. A male sage grouse struts across the lek, hoping to impress the ladies with his moves. Slowly, a female approaches. Certain he’s made an impression, the male begins to strut faster, adjusting his dance to put on his best show. The female seems interested. Unable to contain his excitement, the male hastily jumps on the hen in an attempt to mate. The female hesitates, then starts to flee. Unfazed, the determined male remains balanced on her back. A moment later they both topple into the sagebrush. A camera captures the entire hilarious event.

While it might seem like a first date gone wrong, this was an actual event starring a remote-controlled robotic sage grouse hen being used in a study of mating behaviors of these unique birds.

Each spring, sage grouse gather at leks where males perform elaborate displays to attract females. While many males display, only a select few do the actual mating. Gail Patricelli, professor in the Department of Evolution and Ecology at the University of California, Davis, was interested in how the birds communicate during their courtship rituals and why females select certain males for mating.
“Lekking is one of the coolest ways of selecting mates. I wanted to learn how these crazy behaviors evolved,” she said.  
The female grouse weren’t always cooperative during Patricelli’s observations, so she had to get creative. She worked with engineers at Cornell Lab of Ornithology to develop robot models of a sage grouse which they affectionately dubbed “fembots.”

The first model ran on a track, but the design limited where the robot could move and it often got stuck when scuffling males kicked dirt onto the tracks. So Patricelli created fembot 2.0, a remote-controlled unit which she describes as “a rotisserie chicken on wheels with sage grouse skin attached.” The unit is equipped with a camera and microphone to record a male’s struts and other behavior. Researchers study the video in the lab after the robot is used in the field.

A trio of fembot 2.0s sit on a table waiting to get covered in taxidermied grouse skins and feathers. The skin will cover the shell, microphone and video camera contained within in each unit. Realism is key to measuring what a male sage grouse display looks like from the female perspective. (Photo courtesy of Gail Patricelli, University of California, Davis)

“Fembot 2.0 can tilt forward as if it were foraging, or remain upright, looking like she’s ready to mate,” Patricelli said. This realism allows biologists to examine the amount of effort exhibited by a male in relation to a female’s signals of interest in mating. “The fembot creates a controlled female stimulus and allows us to measure a male’s display from the female’s perspective,” she said.

Fortunately, male sage grouse are easy to fool. They weren’t spooked by the robot. As the example above shows, they even tried to mate with it. “We’ve even witnessed males try to mate with dry cow pies, so the bar’s pretty low for us to fool them,” she said. Still, she was nervous the first time she deployed the robot. “It was nerve wracking, like being on a first date. You don’t want to be rejected by the males.”

The natural behavior exhibited by excited males was exactly what Patricelli was hoping for. “This study gives us a baseline of what sage grouse behavior should be, and what to look for when things go wrong. When we study the birds prior to any disturbance, it can help us identify any differences that we see in their behavior when there is a disturbance in their habitat.”

The fembots help study other aspects of sage grouse behavior. Observing how and where the birds forage helps determine what makes good sage grouse habitat, and a bio-acoustic study is exploring how man-made noise from nearby development can interrupt mating behaviors.

Patricelli said there was a steep learning curve on how to approach strutting males with a fembot, and she had to make adjustments to her approach. She also learned that males aren’t always displaying at their highest effort but seem to be making adjustments as they go.

“A male will strut faster when he knows a female is watching. It’s a tactical response to the female’s behavior. They’re conserving their energy and using it when it matters the most,” she said. “If we take dating advice from a sage grouse it would be this: Don’t dance like no one is watching.”

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