Sage-grouse decline triggers mitigation

SUBLETTE COUNTY – The greater sage-grouse is one of the key wildlife species monitored on the Pinedale Anticline Project Area and when certain numbers show problematic declines, the Bureau of Land Management is required to use mitigation measures built into the project area’s 2008 record of decision.

At the PAPA’s annual operator planning and wildlife monitoring meeting at the Pinedale Field Office on May 25, BLM biologist Mark Thonoff reported that important greater sage-grouse statistics declined enough last year to require onsite mitigation at the Duke’s Triangle complex.

This was the first in-person meeting in three years.

PFO manager Doug Linn welcomed operators, citizens, businesspeople, wildlife biologists and representatives for Rep. Liz Cheney and Sen. Cynthia Lummis.

Each year for this PAPA meeting, Thonoff compares three oil-gas development area sage-grouse complexes – Mesa, Duke’s Triangle and Yellowpoint – with three adjacent reference sage-grouse complexes – Speedway, Ryegrass and East Fork. Numbers are calculated to determine rates of growth or decline; certain combinations of declines serve as wildlife matrix triggers.

“Upper Green River Basin numbers are trending down and that could be due to other environmental factors,” Thonoff said.

Sometimes, declines of population, number of leks or peak male attendance are reported at both sets of complexes.

Data reflect trends that “are very cyclical,” Thonoff said. “We’re definitely in the trough of that cycle, probably at the low end right now.”

For greater sage-grouse – which hover just off the Endangered Species List – current year’s statistics are compared back to the PAPA Record of Decision’s 2007 baseline.

Peak male attendance in Duke’s Triangle dropped to its lowest level of 11, compared to a high of 67 in 2016. In 2020, there were 26 males; overall in Duke’s Triangle there was a 61-percent drop from the baseline, surpassing the threshold.

The development area’s Mesa Complex reported a 30-percent decline in 2021 and Yellowpoint, a 7-percent decline compared to the 2007 baseline.

Peak male attendance for the reference area complexes of Ryegrass and Speedway was down 22 percent, East Fork down 6 percent in the same comparison.

The PAPA ROD also calls for monitoring sage-grouse numbers in the winter concentration area for a 15-percent decline – but it “has never been evaluated for that purpose,” according to Thonoff. “It’s never been measured but it is in the matrix.”

With fewer sage-grouse leks and lower populations overall since 2008, he said, “I would say the development area has an overall negative trend.”

“What happens next,” Thonoff was asked. He pointed to the PAPA ROD regarding onsite mitigation and said many projects work to benefit greater sage-grouse – signs, habitat treatments and fence markings, for example.

Linn said that sage-grouse threshold was only passed “one other time in the past.”

“The Pinedale Anticline Field Office has the function to direct funding to mitigation efforts and it is my responsibility to look into those types of projects,” Linn said.

The interagency team of BLM, Wyoming Game and Fish and other agencies will “look at the PAPA ROD and see if we are meeting criteria laid out in that decision.”

Later, Linn clarified, “It is for onsite mitigation that we would target within Duke’s triangle where possible. Additional mitigation could be anywhere within the Anticline.”

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