Sage grouse will likely go extinct in the Powder River Basin within the next three decades, according to a recent study commissioned by the Pew Charitable Trusts.
Those declines mirror wider trends across the bird's range. The study found sage grouse populations across the West declined by 56 percent between 2007 and 2013. The Wyoming Basin, home to the world's largest sage grouse population, dropped from 50,000 male grouse in 2007 to 20,000 in 2013.
The stakes are especially high in the Powder River Basin, which serves as a link in the bird's range, connecting the Northern Plains to Wyoming and its neighboring states. The number of male sage grouse in the Powder River Basin fell by 76 percent, dropping from 6,804 in 2007 to 1,651 in 2013.
Such declines raise the prospect that the region's grouse could slip into the "extinction vortex," wrote Edward Garton, professor emeritus of wildlife ecology at the University of Idaho and the report's lead author.
"The expanding threat of energy development across the Powder River Basin and declining sage grouse numbers make this overall an at-risk population," he wrote.
The study comes amid a wider escalation in the sage grouse debate. The U.S. Fish and Wildlife Service faces a Sept. 30 court-imposed deadline to decide whether the bird qualifies for protection under the Endangered Species Act.
Agriculture and energy interests fear a listing would greatly hinder development throughout the West, while environmentalists contend additional protections are needed to stem the bird's demise.
The service's deliberations have been overshadowed by recent attempts from Western lawmakers to block an endangered listing. A provision in a spending bill passed by Congress last year prevents the service from making a threatened or endangered finding.
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U.S. Rep. Rob Bishop, a Utah Republican, recently went a step further, attaching a condition to a defense spending bill that would prohibit a decision for 10 years. The bill was passed by the Armed Services Committee last week and now goes to the full House for consideration.
Officials in Wyoming, meanwhile, have focused much of their recent attention on changes to the state's sage grouse conservation strategy. Wyoming's plan restricts development around nesting and mating sites. State officials hope the changes will bolster their contention that they are best placed to manage the bird.
The Pew study was delivered against that backdrop. Grouse in the Powder River Basin faced a "perfect storm" of factors, the study found. Energy development, fractured habitat and the development of disposal pits for produced water led to a spread of West Nile virus.
"I don’t see how the Gillette area in the Powder River Basin can maintain any viability at all in terms of sage grouse populations," said Clait Braun, who studied the bird for three decades as a researcher at the Colorado Division of Wildlife. Braun, who did not participate in the study, has been a vocal critic of state and federal efforts to protect sage grouse.
Wyoming Sage Grouse Coordinator Tom Christiansen said he did not dispute the study's findings. Northeast Wyoming has long been the state's area of greatest concern. Slightly fewer than 50 percent of the sage grouse in the region are protected under Wyoming's conservation plan.
The challenge is that much of the region was already developed when the state implemented its policy in 2005, Christiansen said. The U.S. Bureau of Land Management had already completed several environmental analyses examining coal-bed methane production, which was booming at the time.
Still, Christiansen took issue with the study's time frame. He noted its numbers were from the six years between 2007 and 2013. Sage grouse numbers were up in 2014 and could be increase further this year, he said.
More time is needed to determine if Wyoming's strategy is working, he said.
"If we continue to do what we’ve done from the past 50 years, that will result in extinction," Christiansen said. "Obviously, in the last 10 years things have changed."
Theo Stein, a spokesman for the U.S. Fish and Wildlife Service, called Garton an "important researcher in the greater landscape of scientists." However, he noted the study is just one of many the service will evaluate in making its decision.
Follow energy reporter Benjamin Storrow on Twitter @bstorrow