Western Wyoming emerged as a stronghold for greater sage grouse in a grim federal report that estimates an 81% decline in the species over the last 53 years.
The 260-page U.S. Geological Survey report published March 30 estimates a 3% annual decline over the half-century period, a pace one sage grouse advocate said would lead to the species’ extinction in about three decades.
Conservationists see the report as a dire warning about the species’ fate. Without action, federal wildlife managers could find reason to protect greater sage grouse under the Endangered Species Act, they warned. Such a development would carry widespread implications for Wyoming, where an estimated 38% of the world’s greater sage grouse live in landscapes eyed for oil and gas development, subdivisions and other disturbance. ESA protection could restrict activities, affect state revenues and have other impacts.
While the analysis painted a bleak scenario for grouse across 11 western states, it found a bright spot in western Wyoming.
In that area, excluding Jackson Hole, grouse numbers have increased gradually through several population cycles. Numbers rise and fall during these oscillations and the report’s 11 authors found “slight growth” in western Wyoming dating back to 1996.
“This is the most contiguous habitat available range-wide,” said Peter Coates, Ph.D., the report’s lead author and a research wildlife biologist at the Western Ecological Research Center in Dixon, California. “It’s a lot of uninterrupted habitat.”
The report, an amalgamation of data processed through scientific statistical models, proposes a standard method for counting and estimating greater sage grouse population trends across the West. “Range-Wide Greater Sage-grouse Hierarchical Monitoring Framework,” as it’s titled, also proposes an early-warning system for areas where birds are in trouble.
The report’s models for data-crunching will fill “a prominent information gap” encumbered today by state boundaries and vexing oscillations in grouse numbers, the report states. The publication is “the largest most comprehensive analysis of trends ... that align with the biology of the bird,” Coates said.
The framework should help scientists determine what’s driving population declines and what efforts might be working to stem a tide of losses. The goal is to help “reverse these long-term declines these models have brought out,” Coates said.
The report shows that the U.S. Fish and Wildlife Service faces an increasingly difficult challenge to keep the bird off the ESA’s threatened or endangered lists, Dr. Steve Williams, president of the Wildlife Management Institute and former director of the U.S. Fish and Wildlife Service, said in a statement. “There’s still time to assess the situation and reverse these trends,” he said.
Nobody knows how many greater sage grouse exist in the 11 western states that are their only habitat outside some small locations in Canada. But because the birds gather each spring on breeding grounds, called leks, it’s relatively simple to estimate what’s happening to the population.
Instead of relying on specific numbers to track populations, “trends, for managers are typically more important,” Coates said. Managers ask not how many but “are they increasing or decreasing.”
“We can expect [predict] what’s going to happen to the species with trends regardless of the number,” Coates said.
Experts have estimated that Wyoming might hold anywhere from 200,000 to 500,000 grouse.
Most of the trends remain worrying. In addition to the 81% estimated decline over the last 53 years, authors say there’s a better than 50% chance of losing a significant portion of “lek clusters” — neighborhoods of breeding grounds — in the next half century.
Nearly 30% of those lek clusters have a better than 50% chance to be extirpated or “functionally lost” in the next 56 years, the paper says. Most would be on the periphery of the bird’s range, authors predict.
The paper’s long-winded title suggests the technical nature of its language and research methods (the subtitle is “Implications for Defining Population Boundaries, Trend Estimation, and a Targeted Annual Warning System”) but authors lay out key objectives they achieved. They developed a range-wide database to use in a population monitoring framework. Those tools should standardize states’ methods and consolidate information.
The authors’ models also will enable managers to tease out population fluctuations in small or large areas over different periods — important information that will help them determine successful conservation measures as well as threats. A “targeted annual warning system” is designed to alert managers of trouble spots.
Those would be detected when trends in a local or regional population become “decoupled” from larger tides. Such anomalies would show if either a small or large area is “not gaining population growth when they should be,” Coates said.
The authors resolved a potential problem with some state counting systems based solely on active leks. Under the proposed model, when a lek becomes inactive it will remain in the data set with a zero count and better reflect grouse numbers.
The estimated annual population decline of 3% is about a percentage point more than what had been believed five years ago, said Brian Rutledge, director of the National Audubon Society’s Sagebrush Ecosystem Initiative. “At 3% per year it takes 33 years to knock them out,” he said.
Rutledge is fearful of an ESA listing, he said, in part because responsibility for recovery shifts from the states to the federal government. At the federal level, “we never fund it,” he said of recovery efforts.
“I’m very interested in keeping 11 states working on the recovery of this species,” Rutledge said.
Wyoming submitted data for the report but did not consult with the authors, said Bob Budd, head of Wyoming’s Sage Grouse Implementation Team. He isn’t surprised that western Wyoming remained a stronghold, he said.
“That’s the heart of the range,” Budd said. At the same time, “we’re not going to run out and say we’ve solved all the problems in the world.”
The U.S. Fish and Wildlife Service looks at greater sage grouse trends across the west when considering whether the imperiled bird needs ESA protection. So what happens in other states may affect Wyoming.
Wildfire and cheatgrass invasion are perhaps the most influential factors affecting a large area of greater sage grouse habitat in the Great Basin of Utah, Nevada and Oregon.
The coordination of a monitoring framework among states across the West has been and will continue to be led by Western Association of Fish and Wildlife Agencies, Lief Wiechman, sagebrush ecosystem specialist with the USGS in Fort Collins, Colorado, said.