Study: Tall grass aids sage grouse nesting success

CHEYENNE, Wyo. — Newly published research that examined the relationship between grass height and the greater sage grouse’s nesting success could have implications for cattle and sheep grazing as environmental groups push for federal protection for the chicken-size, ground-dwelling bird.

Researchers studied sage grouse nests at two locations in the Powder River Basin in northeastern Wyoming and southeastern Montana. Over five years, they found the likelihood that at least one egg in a nest would hatch increased when nearby grass was taller, it and decreased when grass was shorter.

Tall grass and healthy sagebrush can help sage grouse hide their eggs from predators such as foxes and badgers, said Jeffrey Beck, a University of Wyoming associate professor and co-author of the study published in the December issue of Wildlife Biology.

“Sometimes it’s even worse where they kill the adult female that’s nesting on the clutch and then eat the eggs up,” Beck said Wednesday.

Three groups — WildEarth Guardians, Western Watersheds Project and the Center for Biological Diversity — pointed to the grass-and-nest study as cause for concern about livestock grazing in sage grouse habitat.

“The more grass cows eat, the fewer sage grouse survive on public lands,” said Randi Spivak with the Center for Biological Diversity.

The groups are among those pushing for Endangered Species Act protection for the greater sage grouse, which inhabit 11 states: California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming.

Cattle grazing occurred in the areas studied, but the researchers didn’t examine how grazing might have affected grass height, Beck said.

“There’s also other things that eat grass too, including grasshoppers,” he said.

Rain and snowfall also affect grass height, and the research from 2003 to 2007 encompassed wet years and dry ones. Still, the researchers suggested that grazing should be considered in sage grouse management.

“Managing grass height in large and intact landscapes with grazing is a tool that may benefit populations in eastern Montana and northeast Wyoming,” they wrote.

More research is needed to evaluate how livestock grazing affects sage grouse habitat, Beck said.

Overgrazing can indeed harm sage grouse habitat, but ranchers can be flexible, said Jim Magagna, executive vice president of the Wyoming Stock Growers Association.

“You can adapt grazing programs to make them more amenable to the grouse,” Magagna said.

Congress recently voted to bar any spending to plan to protect sage grouse as threatened or endangered. Even so, Interior Secretary Sally Jewell said Wednesday that the U.S. Fish and Wildlife Service would stick by its longstanding plan to decide by Sept. 30 whether to list the birds.