Desert bighorn sheep

Desert bighorn sheep (Ovis canadensis nelsoni) is a subspecies of bighorn sheep (Ovis canadensis) that is native to the deserts of the USA's intermountain west and southwestern regions, as well as northwestern Mexico. The trinomial of this species commemorates the American naturalist Edward William Nelson (1855–1934). The characteristics and behavior of desert bighorn sheep generally follow those of other bighorn sheep, except for adaptation to the lack of water in the desert. They can go for extended periods of time without drinking water. The desert bighorn sheep is also the mascot of the Universidad Autónoma de Baja California. The range of desert bighorn sheep includes habitats in the Mojave Desert, Colorado Desert, and Sonoran Desert. Anza-Borrego Desert State Park, Joshua Tree National Park, Death Valley National Park, Kofa National Wildlife Refuge, Cabeza Prieta National Wildlife Refuge, and Mojave National Preserve all offer protected habitat for this animal. Populations of the desert bighorn sheep declined drastically with European colonization of the American Southwest beginning in the 16th century. These declines were followed by a period of population stabilization ascribed to conservation measures. As of 2004, desert bighorn sheep numbers remained extremely low, although the overall population trend had increased since 1960. Desert bighorn sheep are stocky, heavy-bodied sheep, similar in size to mule deer. Weights of mature rams range from 115 to 280 pounds (52 to 127 kg), while ewes are somewhat smaller. Due to their unique concave elastic hooves, bighorn are able to climb the steep, rocky terrain of the desert mountains with speed and agility. They rely on their keen eyesight to detect potential predators, such as mountain lions, coyotes, and bobcats, and they use their climbing ability to escape. Both genders develop horns soon after birth, with horn growth continuing more or less throughout life. Older rams have curling horns measuring over three feet long with more than one foot of circumference at the base. The ewes' horns are much smaller and lighter and do not tend to curl. After eight years of growth, the horns of an adult ram may weigh more than 30 pounds. Annual growth rings indicate the animal's age. The rams may rub their own horns to improve their field of view. Both rams and ewes use their horns as tools to break open cactus, which they consume, and for fighting. Desert bighorn sheep typically live for 10–20 years. The typical diet of a desert bighorn sheep is mainly grasses. When grasses are unavailable, they turn to other food sources, such as sedges, forbs, or cacti.