The new study led by University of Idaho scientist Edward Garton shows that the number of breeding males counted at grouse-mating sites fell by 56 percent from 2007 to 2013, from 109,990 to 48,641.
The surveys were done by state fish and game agencies, except for Colorado, and the population estimates are from those numbers.
The news is bad for 11 states seeking to develop plans with the Bureau of Land Management, Forest Service and other federal agencies that would keep the grouse from being listed as endangered, an act with ramifications for land uses across the West. It comes as several congressmen are pushing legislation that would delay any listing of the sage grouse under the Endangered Species Act.
Besides Garton, the authors of the study included Jack Connelly, who just retired as a biologist from the Idaho Department of Fish and Game, Adam Wells of Washington State University and Jeremy Baumgardt of Texas A&M University. Their research shows that sage grouse populations declined substantially, they wrote, “implying that current policies and programs across both public and private land ownerships that are intended to benefit sage-grouse show little current evidence of success, though optimistically we can hope that it is still too early to detect effects of habitat improvement.”
“Clearly more effort will be required to stabilize these declining populations and ensure their continued persistence in the face of ongoing development and habitat modification in the broad sagebrush region of western North America,” they wrote.
The authors did acknowledge that sage grouse numbers are cyclical and that the birds may be in the bottom end of the cycle. State wildlife officials in several of the 11 states affected say they have seen numbers rise since 2013.
U.S. Fish and Wildlife officials, who will make the call on listing, acknowledged the report.
“We value all peer-reviewed research on greater sage-grouse,” a FWS official said. “We anticipate Dr. Garton’s study will be one of several that helps inform our status review decision.”