Biologists have launched a study of sage grouse in the Bighorn Basin to better understand the bird's movements and the threats it faces.
Jim Pehringer, district supervisor with the U.S. Department of Agriculture's Wildlife Services in northwest Wyoming, said the study began earlier this month and will continue through 2016 if funding allows.
While the basin's sage grouse population remains healthy, Pehringer said, the average number of observed birds continues to linger below peak levels recorded in 2006. The study aims to determine when and where the grouse move, along with the causes of their mortality.
"It's dealing with the predation rate and the major predators of sage grouse," Pehringer said. "Secondarily, it also looks at the human impact on sage grouse in the Bighorn Basin."
Pehringer said the basin's sage grouse are hunted by predators including coyotes, bobcats, badgers, skunks and raccoons. Ravens, magpies and golden eagles have also been known to prey on grouse. Scientists speculate that sage grouse in the basin didn't evolve under the current predation pressures.
Pehringer said that monitoring elsewhere in Wyoming, such as Fremont County, found that 48 percent of sage grouse nests were damaged or destroyed by predators. It also found that common ravens and black-billed magpies accounted for nearly 87 percent of all documented incidents of nest predation.
"I've seen a lot of sage grouse studies, and this is the first one that singles out predation as a possible cause of mortality on sage grouse," Park County Commissioner Joe Tilden said. "I'm in favor of this."
The study has also gained the support of several energy companies.
"There are a lot of oil fields that want to see this project happen," Pehringer said.
Despite the lower numbers, Pehringer said, the basin's sage grouse population is strong.
"We have a lot of grouse in the Bighorn Basin that are currently hunted year to year," he said. "Yet we seem to be under the same restrictions as other states that don't have the sage grouse population that we do."
Reprinted in part from Billings Gazette