Bighorn sheep clinging to crags in California's Sierra Nevada have become disturbingly rare. Around 1850 there were at least a thousand, says the University of California's John Wehausen, who has studied the Sierra Nevada subspecies for 25 years. "We're down to about a hundred adults," he says. Last April the U.S. Fish and Wildlife Service assigned the sheep emergency endangered status. Mountain lions—protected by a hunting ban since 1972—have increased and are killing the sheep. In addition, bighorns usually leave the high country in winter to forage. But fear of lions now prevents them from doing so, and many sheep starve. Five groups have dwindled to fewer than 25 animals; a captive-breeding program is planned.

Reprinted from National Geographic, Nov. 1999