Greater Sage-Grouse populations have declined by 80% range-wide since 1965 and by nearly 40% since 2002, according to a new report by the U.S. Geological Survey. Although the overall trend clearly shows continued population declines over the entire range of the species, rates of change vary regionally.
The report represents the most comprehensive analysis of sage-grouse population trends ever produced and lays out a monitoring framework to assess those trends moving forward. The study can also be used to evaluate the effectiveness of sage-grouse conservation efforts and analyze factors that contribute to habitat loss and population change — all critical information for resource managers.
USGS scientists and colleagues developed the framework to estimate Greater Sage-Grouse population trends in the 11 western states where the species lives — California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. The sage-grouse is a vulnerable species and an indicator of the overall health of the iconic sagebrush ecosystem.
Relative stability in western Wyoming
The research found that in recent decades the rate of decline increased in western portions of the species’ range, particularly in the Great Basin, while the declines have been less severe in eastern areas. Western Wyoming was the only region to show relatively stable sage-grouse populations recently. Taken as a whole, the Greater Sage-Grouse population now is less than a quarter of what it was more than 50 years ago.
To complete the framework, USGS and Colorado State University researchers collaborated with the Western Association of Fish and Wildlife Agencies, individual state wildlife agencies, and the Bureau of Land Management. Together, they compiled information and created a range-wide database of sage-grouse breeding grounds. Researchers used that information to assess past and current sage-grouse population trends in different parts of the species’ range.
In addition to the database and population-trend assessment, researchers also developed a “Targeted Annual Warning System” to alert biologists and managers when local sage-grouse populations begin to decline or have diverged from regional trends. The research identified the most at-risk breeding grounds, finding that the greatest risk is at the periphery of the species’ range.
The report shows that there is only a 50% chance that most breeding grounds, called leks, will be productive about 60 years from now if current conditions persist. USGS scientists will continue to analyze information to determine the factors driving changes in breeding areas and populations, including the influence of habitat loss and degradation.
“The framework we developed will help biologists and managers make timely decisions based on annual monitoring information,” said Peter Coates, USGS scientist and lead author of the report. “This will allow them to address local issues before they have significant impacts on the population.”
Thanks to the U.S. Geological Survey for providing this news.
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