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

2. 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 1980s – Translocations are initially successful
- mountain lion population increase observed

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

4. …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

5. Photo Credits
Slide 1: Bighorn Sheep on Mt. Wilbur in Glacier National Park. Photo courtesy of Kim Keating, USGS. 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. Used in accordance with Attribution-Share Alike 3.0 Unported as described by Creative Commons in their Public License at