Pinto Basin Road Renovation
Pinto Basin Road is being renovated. On weekdays you may encounter travel delays of up to 30 minutes. Cholla Cactus Garden is closed on weekdays. Cottonwood Visitor Center hours are 9 to 4 on weekdays, 8 to 4 weekends. More »
Rattlesnake Canyon Will Remain Closed Through May
To provide additional time to mitigate the vandalism, Rattlesnake Canyon will remain completely closed to the public for another 30 days. More »
Desert Bighorn Sheep
The Desert bighorn, Ovis canadensis nelsoni, ranges through the dry, desert mountains of eastern California, much of Nevada, northwestern Arizona, and southern Utah (range map). The total population of this sheep is about 13,000. Two hundred fifty or so live in Joshua Tree National Park.
Three herds live in the park
Water is critical to bighorn survival. In early spring of years with good winter rains they get enough water from the grass they eat to go without drinking. At other times they must trek to a spring or water-holding depression at least every third day. Lactating ewes need to drink almost every day. Making the trek to water is the most dangerous part of a bighorn's life. It is in the narrow canyons, where most springs occur, that the adult sheep's only significant predator, the mountain lion, Felis concolor, lies in wait. Most dead sheep found in the park are mountain lion kills.
Bighorn have extremely acute eyesight, which aids in jumping and gaining footholds in the steep terrain. They often watch other animals moving at a distance of almost a mile. During the rut, the bighorn rams snort loudly. The lambs bleat, and the ewes respond with a guttural "ba-aa". They also utter throaty rumbles when frightened.
Rams do not defend territories, but do engage in battles over mating access to a particular female. Overall vigor as well as horn size determines male dominance status. Rutting may occur at any time of year, but seems to peak in August and September. Gestation lasts 150 to180 days. Desert bighorn may give birth at any season, but most births occur from January to April. Twins are rare. Within a few weeks of birth, lambs form bands of their own, seeking out their mothers to suckle only occasionally. By six months of age, they are completely weaned.
Only about one-third of the lambs survive the rigor of their first summer. Ewes are usually ready to breed in their second or third year. Males reach sexual maturity at the same age, but are not usually strong enough to compete for mating until they are seven years old. After reaching adulthood, most bighorn live over 10 years, with maximum life span being 20 years.
Happily, the bighorn of Joshua Tree National Park are isolated from areas of livestock grazing and face no competition from feral horses or burros. So far in a 30 plus year research program, our bighorn herds have been judged to be in good condition.
by Harold De Lisle, PhD
Did You Know?
In the high desert country that was to become Joshua Tree National Park, rugged individuals tried their luck at cattle ranching, mining, and homesteading. William Keys and his family are particularly representative of the hard work and ingenuity it took to settle and prosper in the Mojave Desert. More...