Wing data indicates sage grouse population slide will continue - Casper, WY Oil City News
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Wing data indicates sage grouse population slide will continue


December 11, 2019 by Angus M. Thuermer Jr., WyoFile

There’s little prospect for Wyoming’s greater sage grouse population to grow next year and reverse a three-year slide, new data from Wyoming Game and Fish Department suggests. 

A count of hunter-supplied sage grouse wings shows a low ratio of chicks compared to hens, a Game and Fish biologist told WyoFile on Friday, which portends a continuing population decrease.

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Hunters drop the wings into barrels at strategic roadside locations during the hunting season. The ratio indicates how successful the brood-rearing season was in a particular year.

Game and Fish workers collect them for the analysis. The wings — most of which came from central and southwest Wyoming this fall — help determine the status of the imperiled bird, recently a candidate for protection under federal environmental laws.

The preliminary analysis revealed 1.1 chicks per hen in 2019, said Leslie Schreiber, the agency’s sage grouse and sagebrush biologist. For the population to expand, there needs to be 1.5 chicks per hen, she said.

The ratio necessary to maintain a stable population is difficult to tease out, she said. In a statement Monday, Game and Fish put the average population-maintenance ratio at 1.2 chicks per hen.

Biologists counted 667 hen wings and 740 chick wings, according to Game and Fish. 2019’s 1.1 ratio brings the figure “close to the population-maintenance ratio,” the agency wrote.

The data is a predictor of the upcoming 2020 census that’s conducted on grouse breeding grounds. “I would expect a slight decrease compared to 2019,” Schreiber said.

This year’s wing ratio is an improvement over that of 2018, Schreiber said. Last year Game and Fish counted 0.8 chick per hen in the harvest survey.

The news comes as Wyoming, and the rest of the West, is in the third year of declining populations. Biologists aren’t necessarily worried about an individual year’s population estimate, but they see trends, like the three-year slide, as meaningful.

Persistent drought, loss of habitat, invasive species, fire and human influences all likely contribute to the West-wide decline. Grouse populations also fluctuate naturally, Schreiber said.

“Some people use the word ‘cycle,’” she said. “There’s a synchronized fluctuation across the range. I think we’re just in a downward curve in those fluctuations.”

Three-year slide

The three-year trend emerged this summer as wildlife agencies began reporting their spring population estimates. Many of those are based on the number of male grouse seen strutting on leks or breeding grounds.

 From 2016, population estimates are down between 33% (Oregon and Nevada) and 52% (Idaho) in five of the 11 Western states where greater sage grouse live, according to WyoFile calculations. Wyoming’s count of male sage grouse in 2019 was down 21% compared to the year before and down 44% from the most recent zenith in 2016.

WyoFile obtained 2019  population estimates from  five states, including Wyoming and Montana. Those states hold 76.6% of the world’s population, according to the U.S. Fish and Wildlife Service. Collectively, that cohort declined 46% in three years, according to WyoFile calculations.

While population cycles are natural, the most recent downturn takes place while grouse numbers are low to begin with, experts warn.

Some people have criticized the continued hunting of greater sage grouse and hunting-season length and bag limits, including in Idaho. “We know sage-grouse are in trouble and we know much habitat has been lost and that loss is ongoing,” Jack Connelly, a retired Idaho Department of Fish and Game biologist wrote in an op-ed in Idaho’s Bingham County Chronicle. “Given this, caution should be the watchword and at this time decisions should be made in favor of the grouse and not the grouse hunter.”

Despite declines, Wyoming is a greater sage grouse redoubt that holds about 37% of the world’s birds and can tolerate a hunting season without jeopardizing the species, Schreiber said.

“Wyoming is a stronghold for sage grouse,” she said. The state has large, connected coveys and flocks “that can support a huntable population.”

Hunters’ voluntary donation of wings helps biologists, she said. “We appreciate their contribution to learning more about the species through time,” Schreiber said.

Sportsmen and -women also contribute to preservation, she said. “Hunters are the basis for the North American Model of Wildlife Conservation,” she said. “The hunter conservationist is an integral component of that model.”

Two of Wyoming’s four greater sage grouse hunting areas were closed in 2019, including in the west and southeast parts of the state. Where open, the seasons ranged from three to 10 days with a daily limit of two grouse, and a possession limit of four.

Wyoming’s Sage Grouse Implementation Team will continue to work on its conservation efforts, including promulgating Gov. Mark Gordon’s new executive order protecting the bird, team leader Bob Budd told WyoFile on Monday. The core-area strategy seeks to direct development away from key sage grouse habitat, a plan that critics say has been frustrated by the Trump administration’s oil and gas leasing policies.

The low wing ratio, “it wasn’t unexpected,” Budd said. “We are in a down cycle, if you will.

“It isn’t as dire as some predicted earlier this year,” he said. “We’d like to be in a better place. The data show that there are actually some areas that did reach the replacement level,” including in Sublette County.

“I’m not going to say we’re going to hang our hat on that and say everything’s fine,” Budd said. But, it’s “not doom and gloom.”

This article was originally published by WyoFile and is republished here with permission. WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.