Sheep foraging habits help create and maintain biological diversity. In western Oregon, early summer grazing provides black-tailed deer with higher protein vegetation during the critical winter months. Improved rangeland conditions contributed to a significant increase in U.S. wildlife. Idaho uses sheep to manage and enhance mule deer and upland bird habitats. Canada uses sheep on Provincial lands to manage elk and deer habitat.
Sheep eat woody and broadleaf plants as well as tall weeds and grasses.
As a result, sheep are an ideal tool for controlling undergrowth in forests and other wooded areas. This approach benefits the forest environment by eliminating the need for herbicides, it benefits the Forest Service by reducing the need for costly manual clearing, and it benefits communities at risk of wildfires in neighboring forests. In California's Angeles National Forest, northeast of Los Angeles, sheep keep 13,000 acres of ridge-top firebreaks free from flammable chaparral and other brush. Sheep act as brush-control on private lands in northern and southern California, as well as the Pacific Northwest. In Vermont and Alberta, Canada, sheep are used to control brush invasion on ski slopes.