Back from the brink.

• Author: Cohn, Jeffrey
• Position: Protection of pronghorns

MIKE COFFEEN breathes a little easier these days. A US Fish and Wildlife Service biologist who heads the agency's Sonoran pronghorn recovery program, Coffeen has seen wild pronghorn numbers in the United States triple in the last four years. The increase has been largely due to an approach--focused on captive breeding, desert enhancement, and drinking-water supply--that is bringing the US population of this endangered mammal back from the brink of extinction.

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The Sonoran pronghorn is one of five subspecies of pronghorn (Antilocapra Americana)--North America's fastest land animal and the world's second-fastest after the cheetah. Pronghorns once ranged from Canada to Mexico and from the Rocky Mountains to California, with the Sonoran pronghorn extending from southern Arizona and California into Mexico's state of Sonora. Today, the Sonoran pronghorn can be found in the United States only on federal land in southwestern Arizona, with larger numbers in northern Mexico.

Pronghorn are often confused with antelope, deer, and goats, but are only distantly related to those animals. Unlike deer, pronghorn have forked horns, not antlers. Unlike antelope, they shed their horns' outer sheaths annually--and the horns, unlike goats', are solid inside, not hollow. Additionally, pronghorn are the only remaining survivors of a group of North American mammals that nearly died out more than a million years ago.

Once probably numbering in the thousands, the Sonoran pronghorn's US population fell to about 200 by the 1990s as fences, roads, railroad tracks, and other development broke up the animals' habitat, cut them off from sources of food and water, and made them vulnerable to human hunters. Cattle, now gone from federal lands, ate the grasses and other plants pronghorn depend on. Finally, drought hit the Sonoran Desert in 1996, plummeting the number of Sonoran pronghorn in the United States to 21 by 2002, the worst drought year on record in southern Arizona.

Although adapted for desert dwelling, Sonoran pronghorn need at least adequate rains, especially in the summer. Rain promotes nutritious plant growth and water for pregnant and nursing females. If summer rains do not come, plants dry out and turn gray, and few if any fawns survive. Fawns are necessary to replace the 10 percent of adults that die on average every year due to predators...