Two big rams bolted from the steel trailer, took a few hesitant steps and glanced around nervously at their new home: dramatic mountains in west Texas more than 200 miles from where they grew up.

Primarily because of diseases introduced by exotic, domestic sheep grazing in their habitat, Sierra Nevada bighorns experienced a series of dramatic declines in the latter half of the 20th century.

while females' horns never grow larger than one half-spiral. In both sexes, most fur is tan colored; undersides, backs of legs, rump patch, and muzzle are white. Coats shed in patches in June and July ...