Head for the hills! That's exactly what the peninsular bighorn sheep does when a predator threatens, fleeing to higher ground where its uncanny ability to navigate rocky terrain gives it an advantage. It even gives birth to single offspring from the relative safety to steep slopes, as vantage points let the sheep spy out danger before it gets too near. The new generation is entering an increasingly uncertain world, however, facing not age-old nemeses such as mountain lions, bobcats and coyotes, but also threats brought on by human encroachment. From automobile strikes to entanglement in fences, perils are mounting.