About 18 percent of some greater sage grouse populations — a biologically meaningful amount — leave protected core-area zones in winter, University of Wyoming researchers report.
Researchers followed grouse for eight years and one study —covering five of Wyoming’s 31 protective core areas — revealed the winter movement. At least 72 grouse with GPS transmitters were tracked to 44,000 winter locations, including unprotected habitat.
The work shows that more protection for wintering birds may be necessary, the researchers said. “This suggests seasonal use restrictions and other means to avoid impacts should be afforded to areas of winter concentration outside designated Core Areas,” they wrote in an abstract describing their work.
Even when grouse spend the winter in core areas, the studies show birds use that seasonal range seven or eight weeks longer than winter conservation rules, known as stipulations, are in effect.
Jeffrey L. Beck, associate professor of wildlife habitat restoration ecology, Jonathan Dinkins postdoctoral research associate and Kurt Smith, doctoral candidate talked about their research at a wildlife conference in Lander late last year and in interviews. The studies took place near Jeffrey City and in the eastern part of the Bighorn Basin.
“Eighteen percent of [GPS-fitted] individuals that spent at least a portion of their time during nesting season were moving out of core in winter and staying there,” Smith said of one study. “I think it’s a biologically meaningful amount. We need to protect these areas.”
Researchers also found sage grouse are arriving at wintering grounds much earlier — and staying longer — than the period seasonal restrictions protect that habitat. Winter protection, known as “timing limitation stipulations,” for sage grouse extends from Dec. 1 to March 15 in federal and state plans.
“A month and a half earlier they’re moving onto winter grounds,” Dinkins said. Smith said grouse have been seen arriving on winter range on Oct. 7 “and staying about a week longer than seasonal [restriction].”
They made an oral presentation to the joint meeting of the Wyoming Chapter of The Wildlife Society and the Wyoming Landscape Conservation Initiative in early December 2015. They talked during a session about the effectiveness of Wyoming’s core-area conservation strategy.
Some core areas excluded energy leases
Core areas were drawn based on the sites of breeding leks, and an 8.5 km buffer area around. Such boundaries were believed to incorporate most nesting and brood-rearing habitat. It was a “pretty legitimate” strategy, Dinkins said.
But the core areas were “clipped” to exclude some sites targeted for energy development and other uses. “They took that 8.5 km buffer and started carving,” Dinkins said. “Existing leases — they were cut out of some areas.”
Those clippings appear to have affected winter habitat more than summer habitat. “Land use decisions used to construct Core Area boundaries resulted in removing some areas used by female sage-grouse in the winter from Core Area protection,” the researchers’ abstract said.
The clipping did not affect all core areas uniformly, Dinkins said. “Some core areas did a really good job [protecting winter range,] some didn’t.”
Larger core areas appear to contain relatively more wintering habitat than smaller ones, according to the studies. Researchers caution that their studies — they conducted two on core areas and winter range — were undertaken in only eight of the state’s 31 core areas. They said they need information from each wintering population if managers are to create meaningful protections.
“All we can do is look at these individual areas where we have bird [transmitter] locations,” Beck said. But some of the 28 core areas that haven’t been studied may also have sage grouse that leave for winter concentration areas that biologists don’t know about.
“That’s the issue,” Beck said. “We don’t know right now the location of those [winter] areas and how large they are.”
Applying the science comes next
Wyoming has mapped two adjacent winter concentration areas in Southwest Wyoming south of Pinedale. Beck’s goal is to obtain funding “so we can put some more GPS [transmitters] and identify these concentration areas,” he said. “We’d like to do more.”
Thirty-five new GPS transmitters are on order for a continuing study near Jeffrey City, other transmitters were used near Shell and Hyattville in the Bighorn Basin, and researchers also have studied grouse in southwest Wyoming. Biologists and policy makers also are interested in the Sublette County winter concentration areas south of Pinedale where Jonah Energy plans a major gas field.
About half of the wintering area is BLM land in a 141,000-acre unit that’s being analyzed for development with 3,500 wells. The NPL field would be drilled adjacent to the existing Jonah Field.
SGIT did not recommend extending core-area protection to cover NPL. Jonah has said it wants to drill NPL at four times the density that would be allowed under core-area rules. But the company must wait for BLM approval, which is expected to address the winter concentration areas.
“That’s a real focus,” Beck said. “There’s a great interest in the BLM, Wyoming Game and Fish, Jonah Energy — all are interested in those birds. “There’s been quite a lot of conversation and analysis related to that in the last few years.”
Researchers have examined how greater sage grouse react to development of their winter range, Smith said. He was the lead author on a study of energy development on the Atlantic Rim that underscored the need for large continuous blocks of tall sagebrush.
“In essence we found that grouse were avoiding energy infrastructure,” Smith said. “It didn’t necessarily have any influence on survival. Overall, it just shows the importance of continuous sagebrush habitat in the winter.”
In addition to informing SGIT, the researchers hope to collect their studies into one review to be published in a scientific journal.
The effectiveness of the Core-Area Policy is important because the U.S. Bureau of Land Management and Forest Service built grouse conservation plans based on it. The plans were key when the U.S. Fish and Wildlife Service decided last year greater sage grouse no longer needed the protection of the Endangered Species Act.