By Lee Anna Sherman
When Marcy Cottrell Houle headed to the Zumwalt Prairie in the 1980s with her topo maps, tree-climbing gear and raptor leg bands to study hawks, she assumed wildlife and cows were incompatible. After all, that was the prevailing view — and there were millions of overgrazed acres across the West to prove it. So when the OSU grad student found hawks flourishing alongside cows in the northeastern Oregon rangelands, she was stunned.
Livestock, she hypothesized, might actually enhance native ecosystems if — and it’s a big if — it is managed for the health of the vegetation.
A quarter-century later, OSU is following up on Houle’s work with new research at the Zumwalt, one of North America’s last native bunchgrass prairies. A study designed to tease out the optimal stocking rates — cows per acre — for healthy populations of ground-nesting birds began in November 2005 with funding from the National Research Initiative of the USDA Cooperative Research, Education and Extension Service. The research team, led by ecologist and avian specialist Pat Kennedy, will compare the impacts of low, medium and high concentrations of cows on grassland birds of national conservation concern, such as horned larks, western meadowlarks and savannah sparrows. Under investigation, too, are the insects they eat — mainly crickets and grasshoppers — along with soils and plants.
For the experiment, four 400-acre parcels have been fenced off in the Nature Conservancy’s Zumwalt Prairie Preserve. Each parcel has been further divided into pastures, in which different concentrations of cows — from zero to as many as 20 or 30 — will be grazed.
“The range condition of an area of grassland is truly the pulse beat of the health of the ecosystem.”
Marcy Cottrell Houle
The Prairie Keepers
The team hopes to shed more light on those earlier findings of Houle and others — findings that suggest benefits to well-managed grazing. Kennedy, a professor in the Department of Fisheries and Wildlife whose office at OSU’s Eastern Oregon Agricultural Research Center is west of the Zumwalt, just over the Wallowa Mountains, expects moderate numbers of cows to have a neutral — or even positive — impact on the prairie ecosystem. “At very low stocking rates and in areas where there are no cattle,” she explains, “high grass densities may actually be prohibitive for feeding and nesting of native bird populations.”
Kennedy’s colleague Tim DelCurto concurs. “I expect we will see that grazing to a certain degree stimulates good forage rates,” says DelCurto, a beef cattle specialist who runs the Eastern Oregon research center.
And what’s good for forage on the Zumwalt — deep-soiled bunchgrass species such as Idaho fescue and bluebunch wheatgrass — is also good for the cows that eat it. DelCurto calls it a win-win strategy. “We can have our cake,” he says, “and eat it, too.”