ADEL, Ore. — New results from a multi-year study in Oregon's Warner Valley show that removing juniper trees can help sage grouse populations grow more quickly across the West.
The latest findings, published June 9 in the scientific journal Ecosphere, reveal that sage grouse experienced a higher population growth rate in areas where encroaching junipers were removed, versus areas where no trees were cut.
Sage grouse populations have declined across their historical range by 80% since 1965, according to the U.S. Geological Survey.
Meanwhile, the USDA Natural Resources Conservation Service estimates more than 1 million acres of sagebrush grazing lands in the Great Basin have turned into pinyon-juniper forests in the past two decades alone — threatening both rangeland health and sage grouse habitat.
Andrew Olsen, who led the research as a graduate student at Oregon State University, said the expansion of junipers has choked out vegetation like sagebrush and perennial grasses where sage grouse nest.
The birds often avoid trees likely because they provide cover for predators such as golden eagles and coyotes, Olsen said.
"Those are scary environments for them," he said. "They need wide open spaces, not juniper woodlands."
Programs such as the NRCS Sage Grouse Initiative provide landowners with technical and financial assistance for removing junipers on their property to improve habitat. The NRCS has also partnered with the Bureau of Land Management on a large-scale conifer removal effort in the Warner Mountains, beginning in 2010.
Since then, researchers with OSU and the University of Idaho have been tracking sage grouse to determine whether the treatments are effective.
Olsen, who is now a rangeland scientist for the Nature Conservancy in Burns, Ore., spent three years in charge of the study from 2015-17. He earned his doctorate in wildlife science from OSU in 2018.
The project area lies within the BLM's Lakeview District in south-central Oregon, surrounded by the rugged high desert and 7,000-foot mountain peaks.
During the project, 417 hens were captured and fitted with GPS transmitters to monitor their movements. Olsen recalls going out on foot to capture sage grouse at night, enduring freezing cold weather and using spotlights to scan for glowing eyes.
"It's a pretty surreal experience," he said.
The research team observed 378 nests and monitored 223 broods. Ultimately, populations grew at a roughly 12% higher rate in treated areas where junipers had been removed, compared to the control area.
"By targeting removal where sagebrush plants were still intact, we brought instant habitat for a declining bird species," he said.
Ron Alvarado, state conservationist at the NRCS in Portland, said the agency "couldn't be more excited about this new science."
"Our strategic conservation efforts to help ranchers restore sagebrush rangelands are working, and these findings highlight that conservation success," Alvarado said.
The results are also encouraging for ranchers such as John O'Keeffe, who grazes beef cattle on 14,000 deeded acres and 100,000-plus acres of federal permits near Adel, Ore.
Looking back at old photos taken from when he was a kid, O'Keeffe said the parts of the landscape were barely recognizable due to the spread of junipers. Working with the NRCS, he has removed junipers on several thousand acres of his property.
"There's huge benefits to the ranching industry to just take care of the landscape," O'Keeffe said. "We've always had to be sustainable."
Not only does juniper removal boost forage for cattle, but benefits to sage grouse are good news for the industry, O'Keeffe said. The goal is to avoid listing the bird as an endangered species, which he argued would disrupt conservation work on the ground by forcing ranchers to fight for their grazing permits in court.
"When it comes right down to it, listing the sage grouse is not going to help the species," he said.