Between 2007-2013, the greater sage grouse population declined by 56 percent across 11 states. That's according to a study paid for by the Pew Charitable Trusts, which looked at the sage brush habitat as a whole.
This is unwelcome news for people in the West who have been working to keep the sage grouse off the Endangered Species List. The U.S. Fish and Wildlife Service has to make a decision about the listing in September.
Edward Garton is a retired University of Idaho professor and the lead author on the report. Garton collected data across the sage brush range and created models illustrating how the bird has declined in recent years.
Garton says the picture has not improved for sage grouse since the threat of a listing first came about.
"We don't see much evidence that the efforts that have gone on have really had a positive impact," Garton says.
Garton says the results of the study vary depending on the particular threats in different states. In Idaho, the grouse population has fared better than in Wyoming where oil and gas development is prevalent.
But he says Idaho's birds are more susceptible to habitat loss from a different threat; wildfires.
"Large fires will destroy the sagebrush and it will take decades for it to grow back." He points to the Murphy Complex Fire in 2007 as an example of a blaze that wreaked havoc on the sage brush habitat, and says invasive plants like cheatgrass make the landscape more susceptible to fire.
Garton hopes the study will help inform the U.S. Fish and Wildlife's listing decision later this year. He says the data could signify a cyclical downturn in sage grouse, but it's going to be a few more years before scientists can say for sure whether the population decline was natural.
Find reporter Frankie Barnhill on Twitter @FABarnhill
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