LARAMIE – A new study by researchers at the University of Montana shows major declines of sage grouse populations in the coalbed methane fields of the Powder River Basin.

The study, Sage-grouse Population Response to Coal-bed Natural Gas Development in the Powder River Basin by David E. Naugle and colleagues, was commissioned by the Miles City office of the Bureau of Land Management. Naugle has also researched the impacts of West Nile Virus on sage grouse in the Powder River Basin CBM fields.

“This study shows that current methods of coalbed methane development aren’t compatible with maintaining healthy populations of sage grouse,” said Erik Molvar, Wildlife Biologist with Biodiversity Conservation Alliance. “The serious decline in sage grouse populations in the Powder River Basin, added to the 80,000 coalbed methane wells approved for the area by the BLM, add up to big trouble for this important population.”

Naugle will be presenting his findings at 10:30 a.m. tomorrow, June 14th, at an Interagency Working Group meeting at the BLM’s Buffalo Field Office in Buffalo, Wyoming. The meeting is open to the public.

The study documents an overall 84% decline in the sage grouse population since 1988, and shows significant recent declines, a period when sage grouse populations elsewhere are believed to be stable.

“Data from 2000-2005 suggest that leks within CBNG development showed substantially lower population indices than leks outside CBNG development (Figure 3).  This result does not change even after removing data from leks in the Spotted Horse region where West Nile virus largely extirpated sage-grouse populations between 2003 and 2004,” Naugle said in the study.

The study found that sage grouse populations within coalbed methane fields declined more sharply relative to undisturbed populations, and also failed to rebound and show the rapid population growth that was enjoyed by populations in undeveloped areas in 2004 and 2005.

Sage grouse leks, or breeding sites, within coalbed methane fields were either abandoned or significantly reduced.

“One of the most striking patterns we discovered was that, of leks counted in either 2004 or 2005, no medium or large-sized leks occurred within CBNG [coalbed natural gas] development; all remaining leks in CBNG have 20 or fewer males (Figure 5),” Naugle said  in the study.

The researchers concluded, “Our analyses suggest that CBNG is having negative impacts on sage-grouse populations over and above long-term declines seen across the entire region.”

The population trends found in Naugle’s Powder River Basin study suggest that sage grouse are being pushed out of developed areas, a similar result as was found in the Upper Green River Valley gas fields by Matt Holloran in a University of Wyoming study released earlier this year, Molvar said.

“This study shows that previous studies showing sage grouse declines in the gas fields of western Wyoming were no fluke,” added Molvar. “If we can’t find different patterns of drilling that allow the sage grouse to survive, then the development that’s being approved today will almost certainly drive this magnificent bird to the brink of extinction.”

The Naugle study is available for review online at www.voiceforthewild.org/SageGrouseStudies.

Erik Molvar, Wildlife Biologist, Biodiversity Conservation Alliance, (307) 742-7978