Brief History of the Bighorn Sheep Ice Age

Brief History of the Bighorn Sheep Ice Age: Ancestor bighorns from Asia migrate into California 1860 s – domestic sheep grazing in the Sierra Nevadas begins 1870 s – Bighorn populations begin to decline 1876 – California bans sport hunting of bighorns, but population decline persists 1940 s – Biologists estimate <400 individuals left in 5 isolated populations

Brief History of the Bighorn Sheep 1972 – Bighorn sheep listed as Endangered under the California Endangered Species Act - state bans sport lion hunting first recorded livestock depredation 1978 – 250 bighorn sheep left in 2 isolated populations 1979 – Bighorn translocations begin Early 1980 s – Translocations are initially successful - mountain lion population increase observed

Brief History of the Bighorn Sheep Late 1980 s – 49 bighorns killed by lions - bighorn sheep abandon winter ranges 1990 – Voters of California pass Proposition 117 1990 s – Bighorn populations decline, and decline, until… 1999 – Assembly Bill 560 goes before California legislature

…Where are they now? 1999 – Emergency listing of Bighorn Sheep as Endangered under Federal ESA 2000 – “Permanent” Endangered status 2005 – Recovery plan drafted, but still no Critical Habitat Designation for Bighorn Sheep - Current population: 350 - Major threat: disease from domestic sheep

Photo Credits • Slide 1: Bighorn Sheep on Mt. Wilbur in Glacier National Park. Photo courtesy of Kim Keating, USGS. http: //nrmsc. usgs. gov/node/433 This image is in the public domain because it contains materials that originally came from the United States Geological Survey, an agency of the United States Department of Interior. • Slides 2 and 3: Bighorn Sheep (Male), Near Jasper, Alberta. Copyright © 2007, Alan D. Wilson. http: //www. naturespicsonline. com/Nature 32/index. htm? 5 Used in accordance with Attribution-Share Alike 3. 0 Unported as described by Creative Commons in their Public License at http: //creativecommons. org/licenses/by-sa/3. 0/