Data from pictograph and archaeological sites in northeastern California are used to verify the postulated former existence of small resident populations of bighorn sheep (Ovis canadensis) in this region. The reason for the disappearance of bighorns from this area remains unclear, with climatic change, Euro-American settlement, or hunting pressure existing as possibilities.
Schulz, Peter D. and Simons, Dwight D.
"Prehistoric bighorn sheep in the northern Sierra Nevada, California,"
Great Basin Naturalist: Vol. 33
, Article 3.
Available at: http://scholarsarchive.byu.edu/gbn/vol33/iss4/3