Endangered Mammals - Bighorn Sheep

A hundred years ago, desert bighorn sheep were commonly seen climbing the mountains of the American West. The species is named for its large, curved horns, which males use to battle for access to females, wrestling with horns interlocked. Overhunting and disease have decimated bighorn sheep populations across the U.S. In Texas, for FIGURE 7.10
The orangutan is highly endangered, along with the majority of the world's primate species. (Field Mark Publications) example, the number of bighorn sheep had fallen to 500 by 1903, when hunting was finally banned. In 1945 the state set aside 11,625 acres for bighorn sheep habitat in the Sierra Diablo Wildlife Management Area near Big Bend National Park. As populations continued to decline, Texas began to import desert bighorns from other states for captive breeding. Despite these efforts, the last native bighorn in Texas is believed to have died in the 1960s.

Since then, however, new management efforts have met with some success. Private landowners have donated the use of thousands of acres of mountainous terrain as breeding grounds for reintroduced bighorns. Unlike other subjects of restoration efforts, such as wolves, bighorns pose no threats to ranchers—they do not prey on livestock, and they graze in remote areas, where they do not compete with livestock. Bighorn sheep also offer landowners potential income through the sale of hunting permits—when biologists determine the sheep population has surplus rams, the state may issue a limited number of hunting permits. The permits are rare and are very expensive, frequently commanding five-figure prices. They are issued only to landowners participating in the restoration effort. The first Texas permit sold for $61,000. In 1993 a hunter paid more than $300,000 at auction for an Arizona permit. Money raised from hunting permits is put back into bighorn sheep conservation. In 1998 experts estimated the population of bighorn sheep in Texas at 320 and at almost 30,000 nationwide.

In 1998 the Fish and Wildlife Service proposed an emergency endangered listing for the California peninsular bighorn sheep, a subspecies of the common bighorn. In July 2000 the Fish and Wildlife Service proposed critical habitat for these sheep. Estimated at 1.5 million in the early 1800s, the population size had dwindled due to disease, overhunting, loss of habitat, fragmentation of habitat, and predation. A helicopter survey conducted in fall 2000 estimated that some the population of peninsular bighorn is around four hundred.

FIGURE 7.11
Bison are the largest terrestrial animals in North America. (Field Mark Publications)