An icy wind rakes the sagebrush on a sandy knoll at Red Rock Lakes National Wildlife Refuge. The gusts remind you how harsh this mountain corridor of western Montana can be. But the rare sandhill ecosystem at your feet welcomes nature’s beatings.

How much disturbance do these roughly 4,000 acres of sandhills need? What form should it take? How can the refuge provide it while protecting migratory birds and other wildlife?

Refuge biologists are conducting field studies over the next two or three years to find out. With The Nature Conservancy, the Bureau of Land Management and the University of Montana Western, they’re measuring how birds and insects respond to various disturbances. They’re analyzing the chemical makeup of the plasma and feathers of brewer’s and vesper sparrows to “determine what [the birds] are eating … and at what stages they’re eating it,” says refuge manager Bill West. “It’s pretty amazing.”

The survival of rare plant and animal species hangs on their efforts.

These include three invertebrates—the St. Anthony dune tiger beetle, the big sand tiger beetle and a ladybird beetle said to be the rarest in the country. There are also uncommon wildflowers: painted milkvetch, fendler cat’s–eye and pale evening primrose.

“All these rare plant and invertebrate species rely on early seral habitat”—a first stage of ecological succession found in sand environments, says refuge biologist Kyle Cutting. “Early seral means the sand is actively moving; it’s being blown about.”

The refuge acquired these sandhill acres in 2007 from TNC after the nonprofit bought 7,000 acres from a private landowner. TNC kept 3,000 of the acres, to manage with BLM.

Today, the refuge sandhills are in late succession stage. Returning them to an earlier stage is tricky. Historically, fire and bison grazing shaped the sandhills, but neither is an option for the refuge. Concern for sage–grouse precludes large–scale prescribed fire because the ground–dwelling bird (a candidate for endangered species status) is dependent on sagebrush. “Basin big sagebrush—the predominant sagebrush in the refuge sandhills—takes between 20 to 55 years to recover after fire,” says Cutting.

Bison grazing carries its own issues. Citing damage to fences and livestock, neighboring ranchers oppose free–roaming bison, some of which carry brucellosis, which can infect livestock.

That leaves one option: cattle grazing. Red Rock Lakes Refuge uses it outside the sandhills. But the refuge wants more evidence the sandhills will benefit before it applies its standard prescription—one graze per area every fourth year. The study is providing it.

Biological sampling, says Cutting, has shown higher levels of insects and bird forage in the off–refuge western sandhills—“the area that’s been intensively managed with grazing and fire”—than in less disturbed refuge acreage to the east. Bird counts are comparable throughout. “So that gives the refuge reassurance,” says Cutting. “It could justify intensive targeted grazing in the eastern portion.”

Refuge manager West is used to convincing skeptics of grazing’s benefits. Unlike the Forest Service or BLM, the refuge does not give private landowners the right to graze on public land. “We use grazing only in a prescriptive way. There’s no expectation that because we let you do it this year, you can do it next year.”

“Some people think letting the land lay idle is better management,” says West. “It’s not.” Outside the sandhills, “we see no appreciable wildlife response improvement after three years of rest. So that’s the point at which we go back in” and graze.

Next up for study: how bird reproductive success compares on intensely managed versus less managed sandhill acres. If there’s no marked difference, look for grazing to help re–create early seral habitat on the refuge.

Susan Morse is a writer–editor in the Refuge System Branch of Communications.