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
Painted Desert (Arizona) Triassic period coniferous forest have fossilized over millions of years. Wind, water and soil erosion continue to change the face of the landscape by shifting sediment and exposing layers of the Chinle Formation. An assortment of fossilized prehistoric plants and animals are found in the region, as well as dinosaur tracks and the evidence of early human habitation. The Painted Desert extends roughly from Cameron–Tuba City southeast to past Holbrook and the Petrified Forest National Park. The desert is about long by about wide, making it roughly in area. Bordering southwest and south is the Mogollon Plateau, and on the