Sonoran Desert Pronghorn

by Thomas Edgar       

The Sonoran Pronghorn (Antilocapra Americana Sonoresis) is found in the Sonoran Desert in southwest Arizona as well as Mexico. The Sonoran Pronghorn is currently endangered, and in 2003 the U.S. Fish and Wildlife Service estimated that only twenty-one existed.^[1] Organizations such as the USFWS have made efforts to attempt to restore  the Sonoran Pronghorn. The dwindling population is a testament to the adverse effects of human interruption.

Sonoran Pronghorns stands three feet at the shoulder. They have a reddish brown coloring on their back, a lighter color on their undersides, and white markings on their heads and necks. Black faces and patches on their necks distinguish the males from the females. The males also have longer horns (thirteen inches for males, three inches for females) and weigh more as well (one hundred and twenty pounds for males, one hundred and five pounds for females). Sonoran Pronghorns have a top running speed of sixty miles per hour. They typically have a lifespan of nine years.^[2]

The Sonoran Pronghorn subsists on herbs, cacti and desert grasses. The desert does not provide a lot of food due to the fact that rainfall is minimal and sporadic. To adapt to these conditions the Pronghorn has four stomachs. This allows for better digestion of rough textured foods such as cacti. Having four stomachs also maximizes water retention.^[3]

The Sonoran Pronghorn population struggles due to both human and natural factors. Competition for limited food supply comes from excessive cattle grazing. Cattle were removed from the Cabeza Prieta National Wildlife Refuge in 1983 as well as from Organ Pipe Cactus National monument in 1978.^[4] This removal has helped, but does not completely alleviate the problem. Roads, fences and other structures impede the wide foraging area necessary for the pronghorn. The climate also creates problems for the Sonoran Pronghorn. A lack of rainfall makes life difficult for nursing mothers as well as weaned fawns. A 13-month drought, beginning in 2002, reduced the Sonoran Pronghorn population to only twenty-one.^[5]

The U.S. Fish and Wildlife Service used a selective breeding program to help increase the Sonoran Pronghorn population. The program began in 2003 and the first pronghorn were released in 2006.^[6] The USFWS created a six hundred and forty acre enclosure to house the captured pronghorn.^[7] The program required that human contact be kept to a minimum to keep the pronghorn as wild as possible.^[8] The Cabeza Prieta National Wildlife Refuge has a Sonoran Pronghorn population, which it helps by providing more food and water than nature provides.^[9] The species have been on the federal endangered list since June 2, 1970. Presently, there are roughly 750 Sonoran Pronghorn alive. Roughly 100 live in the United States as well as 650 in Mexico.^[10]

Further Reading

Cooperative Conservation America. “Sonoran Pronghorn Captive Breeding Program.” http://www.cooperativeconservation.org/viewproject.asp?pid=407 (accessed February 15, 2012).

Environmental Protection Agency. “Summary of the Endangered Species Act.” http://www.epa.gov/lawsregs/laws/esa.html (accessed February 15, 2012).

National Park Service. “Sonoran Pronghorn.” Organ Pipe Cactus National Monument. http://www.nps.gov/orpi/naturescience/pronghorn.htm (accessed February 15, 2012).

Rex Vogel. “Sonoran Pronghorn Makes Comeback: Cabeza Prieta National Wildlife Refuge, AZ.” Vogel Talks RVing. http://vogeltalksrving.com/2011/01/sonoran-pronghorns-make-comeback-cabeza-prieta-national-wildlife-refuge-az/ (accessed February 15, 2012).