Mount Williamson is in the California Bighorn Sheep Zoological Area and these rare animals can often be seen on the lower slopes during the winter when heavy snows drive the sheep down from their summer grazing areas. From 1981 until 2010 the California Bighorn Sheep Zoological Area was closed to access for much of the year, but late in 2010, the Inyo National Forest Service declined to renew the closure, opening the area to access year-round.