Survivorship and cause-specific mortality in sympatric populations of mountain sheep and mule deer

We examined survivorship and cause-specific mortality in sympatric populati ons of mountain sheep, Ovis canadensis, and mule deer, Odocoileus hemionus, inhabiting a remote region of California. Predation by mountain lions, Fum e concolor, was confirmed in 75% (n = 9) of sheep deaths and 55% (n = 5) of investigated deer deaths. Overall, sheep end deer survived at nearly ident ical rates; however, female sheep survived at a significantly higher rate t han did males, consistent with the hypothesis that differential use of habi tats by gender results in greater risk to males. In California, there are i ndications that impacts by mountain lions to mountain sheep populations are restricted to areas where mountain sheep and mule deer are sympatric.