Visitors enjoying Cooper Mountain Nature Park’s breathtaking views, trails and wildflowers this spring and summer might also encounter a new, temporary addition: cattle.
As part of efforts to restore native prairies, a pilot project that started May 1 has brought six cattle to Cooper Mountain’s prairies to graze. Grazing is a traditional and effective method of land management. The cattle are being evaluated as a possible “partner” to help maintain a healthy prairie by controlling weeds and creating space for native, rare wildflowers to flourish.
“Flowers drive the food web in prairies,” said Curt Zonick, a senior natural resources scientist at Metro who is leading the grazing project. “A prairie that doesn’t have prescribed burns or grazing becomes a field of grass eventually. Grass will outcompete wildflowers.”
Cooper Mountain is a partnership between Metro, which owns the site, and the Tualatin Hills Park & Recreation District, which provides day-to-day management. The 232-acre park includes more than three miles of trails that pass through forests, prairies and oak woodlands.
Historically, grazing elk or deer would have munched their way through Cooper Mountain’s prairies. Although deer still graze at the park, they are no match for a host of new invasive weeds, such as tall oat grass, bird vetch and creeping velvet grass. The weeds overtop native grasses and flowers during the summer growing season and threaten to overrun the park’s prairies.
“Grazing creates bare soil and opportunities for wildflowers to grow,” Zonick said. “When a wildflower seed drops in a prairie that has been grazed, there’s a chance it will land on bare soil instead of a three-inch layer of grass.”
Wildflowers form the critical heart of healthy prairies by luring insects with the promise of nectar. In turn, the insects provide food for a variety of birds and wildlife. A prairie rich in wildflowers is rich in wildlife.
The cattle will be particularly handy along rocky slopes, where mowing and other methods are less successful.
Cooper Mountain is home to one of the regions’ most diverse plant communities, including native wildflowers that are listed by the state and federal government as endangered. For instance, Cooper Mountain is home to the federally endangered golden paintbrush and the largest population of white rock larkspur, which is listed by the state as endangered.
Staff and volunteers from Metro’s Native Plant Center collect seeds from these rare flowers and use them to grow more flowers that help restore native vegetation at natural areas throughout the region.
When the cattle are on site in the spring and summer, visitors will see signs posted at the parking lot and trailhead. Visitors will also encounter signs along the trails alerting them to grazing cattle ahead.
The cattle will be limited to grazing in an area bordered by a temporary electric fence, which will be moved periodically as the cattle make their way across the prairie. The fence could deliver a mild shock to people who come into contact with it, so visitors are asked to please continue to remain on the trails. Visitors are also asked to refrain from petting or feeding the animals.
Cattle will likely also graze at the park in the spring and summer of 2016 and 2017. At the end of the pilot project, staff will review the results to evaluate whether the grazing proved successful.
“We’re not going to know until we try it,” Zonick said. “But there’s a good chance that this could be a good tool.”