BOISE, Idaho — If increasingly destructive wildfires in the Great Basin can't be stopped, the sage grouse population will be cut in half over the next three decades, scientists say.
A report released Thursday by the U.S. Geological Survey comes just ahead of a court-ordered Sept. 30 deadline faced by the U.S. Fish and Wildlife Service to decide whether sage grouse need protection under the Endangered Species Act. Experts say such a listing could damage Western states' economies.
"The sagebrush steppe and sagebrush ecosystem are in trouble," said Matt Brooks, a fire ecologist with the USGS and one of the report's authors.
The study also identified potential ways to avert sage grouse declines by classifying areas for their resilience to disturbance and resistance to invasive species such as cheatgrass, and then applying suitable strategies. Public land managers have already been doing that, but the USGS report could fine tune those efforts.
"It adds to the science that managers, and especially fire managers, can use," said John Freemuth, a Boise State University professor and public lands expert. He said the report could factor into a sage grouse listing decision.
"That's an indication that in the future (managers) will apply resources more effectively to protect the habitat," he said.
The report is also in line with an order by Interior Secretary Sally Jewell in January calling for a new wildfire-fighting strategy using a "science-based" approach to protect wide swaths of the intermountain West sagebrush country that supports cattle ranching and struggling sage grouse.
Looming through much of the USGS report is cheatgrass, an invasive, fire-prone species that wipes out sagebrush ecosystems with wildfire as its main weapon.
"Management of cheatgrass is definitely a key," Brooks said.
The study that examined 30 years of data up to 2013 found that burned areas near sage grouse breeding grounds nullified population growth that would normally occur after years with high precipitation. The study also looked ahead 30 years at projected wildfires and recovery rates of burned areas and predicted long-term population declines in the study area that included Nevada, Utah, Idaho, Oregon and California.
"Habitat degradation within the Great Basin ecoregion of the Intermountain West of North America is a contemporary example of how disturbance is driving rapid changes in ecosystem structure and function across enormous spatial scales," the report said.
The 43-page study didn't include a 436-square-mile wildfire in southwest Idaho in August that destroyed 297 square miles of sage grouse habitat, 83 square miles of that considered priority habitat that contained breeding grounds, called leks.
Rehabilitation efforts drew a high-visibility visit by the director of the U.S. Bureau of Land Management, Neil Kornze, to Idaho, who noted the agency's concerns about a potential sage grouse listing as a reason for the trip.
The chicken-sized, ground-dwelling bird ranges across 11 western states, with much of its habitat administered by the BLM. The birds once numbered in the millions but now have an estimated population of 200,000 to 500,000.
Sage grouse are one of some 400 species that use the sage brush steppe. But scientists consider sage grouse an indicator of the overall health of the sagebrush steppe, sometimes called the sagebrush sea for the vast areas it covers and which is also facing challenges.
"It's so much beyond a bird," Freemuth said of the potential listing. "It's people's lifestyle. It's people's recreational opportunities. It's everything. The bird is just the symbol of all that."