The Sonoran pronghorn is a sub-species of the American pronghorn that lives in Arizona and New Mexico. It has been protected by the Endangered Species Act since 1967.

In 1824, there were more than 30 million pronghorn of all types, including the Sonoran. Less than one hundred years later, in 1915, they were near extinction with only about 15,000 left. Today, there are about 670,000 pronghorn living on America's prairies and deserts.

In the 1800s, pronghorns were easy to shoot for eastern American meat markets. The pronghorn's curiosity attracted them to handkerchief decoys — the fabric flapping in the wind. By the mid-nineteenth century, with the invention of repeating rifles and the extension of railroads into the West, the pronghorn's fate was almost sealed. In the 1870s, hunters reportedly killed thousands of pronghorn each year in Yellowstone National Park.

In 1922, the first regulations to protect the Sonoran pronghorn were put in place. A 1923 survey estimated 75 Sonoran pronghorn existed in southwestern Arizona, a few lived on the Tohono O'odham Reservation in south-central Arizona, and five inhabited California's Sonoran Desert.

In the 1930s, there was growing concern about all southwestern desert species. Conservationists proposed a four-million-acre federal desert wildlife refuge, in part to protect the Sonoran pronghorn. Ranchers opposed the plan, and in the end, less than two million acres were set aside. This protected area included Organ Pipe Cactus National Monument and what are today the Kofa and Cabeza Prieta National Wildlife Refuges. Much of the remaining two million acres were included in a military gunnery range at the outset of World War II.

In 1937, the New Mexico Department of Fish and Game relocated pronghorn from abundant populations to areas where few or no pronghorn existed. The project was a success, and other states followed suit. Studies that demonstrated a difference in pronghorn and cattle grazing preferences and proved that pronghorn do not spread the disease brucellosis helped to build support among the ranching community.

By 1950, the Sonoran pronghorn was extinct in California and north of the Gila River in Arizona. Soon after, it was extirpated from Baja California. In 1967, it was listed under the Endangered Species Act.

In 1982, U.S. Fish and Wildlife Service scientists crafted a recovery plan for the Sonoran pronghorn. Since little was known about the species, the plan focused on studying pronghorn biology and behavior. The Arizona Game and Fish Department researched range and diet and conducted a radio-collar monitoring study. Scientists learned that the subspecies migrates seasonally, especially during periods of poor forage, but contrary to initial theories, it does not migrate into Mexico.

The U.S. Fish and Wildlife Service set a population of 300 Sonoran pronghorn as its recovery goal. Some conservationists judge this to be unattainable, as viable desert habitat is limited and much of the Sonoran pronghorn's former range is now fragmented by development. Captive breeding and relocation is also a possibility, but it has never been attempted with the Sonoran subspecies. One critical step is reducing fawn mortality, which has ranged from about 75 to 100 percent in recent years. Scientists believe this high rate results primarily from poor environmental conditions.

Another U.S. Fish and Wildlife Service goal is to establish a second population that can remain stable for five years. The Sonoran pronghorn recovery team had explored starting a new herd of Sonoran pronghorn in Arizona. Thirty pronghorn from the current population would be needed — a substantial number to remove from an already struggling population. Scientists need to know more about the pronghorn's habitat requirements to know that the transplant site would work. The Fish and Wildlife Service is still working to lay the groundwork for a reintroduction project — both biologically and politically.

Congress declared more than 90 percent of Arizona's Cabeza Prieta and Organ Pipe Cactus National Wildlife Refuges as wilderness area, protected from roads, development, and motor vehicles. All cattle have been removed from pronghorn range, improving grazing areas and allowing pronghorn to move back into territory they vacated when livestock arrived. Scientists are still studying the long-term repercussions of cattle grazing on what was previously adequate Sonoran habitat. Some conservationists are also pressuring the U.S. military to modify air and ground activities to reduce potential impact on nearby pronghorn populations. Reducing habitat fragmentation from oil and gas development, highways, fences and land conversion will all have a beneficial effect on pronghorn.

Scientists track pronghorn movements with radio collars in order to learn about pronghorn biology and range. Biologists have also been studying how water and plant availability affect pronghorn use of habitat areas and how the animals react to human disturbance, especially disturbance from military activities near Cabeza Prieta.

Scientists are working on planting vegetation to supplement the pronghorn's food sources, providing additional water to the area and removing fences that deter pronghorn from coming into areas with water on Cabeza Prieta National Wildlife Refuge.