Little Bighorn River Bighorns have rattlesnakes because they also support a habitat for small mammals, like a mouse and chipmunk population, which are the prey of rattlesnakes. With the restoration of the black bear population in the Bighorn Mountains, there has been a resurgence of black bear living along the stream as it flows out of Montana, extending down the Little Bighorn Valley in Montana. Ranchers between the mouth of the canyon (at about the Wyoming Montana line) down to Wyola often report black bear groups living in the timber along the river, and travelers on the Montana portion of the Little Horn
Desert bighorn sheep establish two desert areas in southwestern Arizona to help preserve the desert bighorn sheep: Cabeza Prieta National Wildlife Refuge and the Kofa National Wildlife Refuge. In 1941, the San Andres National Wildlife Refuge in New Mexico was added. Desert bighorn sheep populations have trended upward since the 1960s when their population was estimated at 6,700-8,100. The upward trend was caused by conservation measures, including habitat preservation. In 1980, desert bighorn sheep populations were estimated at 8,415-9,040. A state-by-state survey was conducted a few years later and estimated the overall US desert bighorn sheep population at 15,980. The 1993 estimate of