Desert bighorn sheep

The range of the desert bighorn sheep includes habitats in the Mojave Desert, Sonoran Desert, Great Basin Desert, and Chihuahuan Desert, as well as the Colorado Plateau. Anza-Borrego Desert State Park, Joshua Tree National Park, Death Valley National Park, Kofa National Wildlife Refuge, Cabeza Prieta National Wildlife Refuge, Zion National Park, Capitol Reef, and Mojave National Preserve all offer protected habitat for them. The subspecies is considered extirpated from Oregon. As of 2004, desert bighorn sheep numbers remained extremely low, although the overall population trend had increased since 1960. ==Characteristics==

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. The typical diet of a desert bighorn sheep is mainly grasses. Southern desert bighorn sheep are adapted to a desert mountain environment with little or no permanent water. Some may go without visiting water for weeks or months, sustaining their body moisture from food and from rainwater collected in temporary rock pools. They may have the ability to lose up to 30% of their body weight and still survive. After drinking water, they quickly recover from their dehydrated condition. Wildlife ecologists are just beginning to study the importance of this adaptive strategy, which has allowed small bands of desert bighorns to survive in areas too dry for many of their predators. Social life Desert bighorn sheep are social, forming herds of eight to 10 individuals; sometimes herds of 100 are observed. Rams battle to determine the dominant animal, which then gains possession of the ewes. Facing each other, rams charge head-on from distances of or more, crashing their massive horns together with tremendous impact, until one or the other ceases. Desert bighorn sheep live in separate ram and ewe bands most of the year. They gather during the breeding season (usually July–October), but breeding may occur anytime in the desert due to suitable climatic conditions. Gestation lasts 150–180 days, and the lambs are usually born in late winter. ==Conservation status and trends==

The number of desert bighorn sheep in North America in prehistoric times is unknown, but most likely was in the tens of thousands. In 1939, after intense lobbying by Frederick Russell Burnham and the Arizona Boy Scouts, President Franklin D. Roosevelt signed a proclamation to 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. The upward trend was caused by conservation measures, including habitat preservation. In 1978, desert bighorn sheep populations were estimated at 8,415-9,040. A state-by-state survey published in 1985 estimated the overall US desert bighorn sheep population at 15,980. The 1993 estimate of the population is 18,965-19,040. In southern California, by 1998, only 280 individuals of the peninsular bighorn sheep population remained, and that population was added to the list of the United States' most imperiled animal populations. Populations in three southern counties had suffered greatly from disease, development, and predation. As of 2008, about 800 peninsular bighorns are believed to populate the desert backcountry from the US-Mexico border to the San Jacinto Mountains, with known populations in Anza-Borrego Desert State Park. These gains, combined with Bush administration policies, prompted the US Fish and Wildlife Service to propose a reduction in protected sheep habitat by more than 50%, from . In southern Texas, desert bighorn sheep conservation began in 1973 with the release of seven captive-bred sheep in the Sierra Diablo Mountains. Captive-bred sheep were periodically released in this area until 1997. The Elephant Mountain Wildlife Management Area herd began with 20 sheep total in 1987. The Elephant Mountain population has increased substantially, and this population has been the source for most translocation efforts in the state so far. The Sierra Vieja population started in 1987 with 5 sheep, and from 2014 to 2015, an additional 76 sheep were released, half of them fitted with radio telemetry collars to understand their movements more. The Van Horn population came from wild-caught Nevada sheep in 1987. In 2020, three Texas Parks and Wildlife Department employees died in a helicopter accident working on desert bighorn sheep conservation. On December 4, 2024, 77 desert bighorn sheep were successfully transported from the Elephant Mountain WMA and released at Franklin Mountains State Park, including many pregnant ewes. Prior to release, all animals were fitted with GPS collars, tagged, and tested negative for the Mycoplasma ovipneumonia bacteria. == In popular culture ==

In 2023 the desert bighorn was featured on a United States Postal Service Forever stamp as part of the Endangered Species set, based on a photograph from Joel Sartore's Photo Ark. The stamp was dedicated at a ceremony at the National Grasslands Visitor Center in Wall, South Dakota. ==References==