Sonoran Pronghorn Antelope Antilocapra americana sonoriensis
The Sonoran Pronghorn is a desert subspecies of the antelope family. Upper parts of the Pronghorn are tan; the underpart, rump, and two bands across the neck are white. The male has two black cheek patches and black horns. Both sexes have horns; males have larger horns. Males weigh 100130 pounds, females weigh 75100 pounds. Pronghorn are well adapted for speed and predator detection. Their long, slender legs and efficient respiratory system allow them to run as fast as 60 miles per hour. Antelope have evolved in an environ-ment with little to no drinking water. They drink when water is available; otherwise, their water needs appear very low.1
Within the Sonoran desert, the pronghorn is found in broad, alluvial valleys separated by granite mountains and mesas. Vegetation is scarce throughout most the Sonoran pronghorn's habitat due to little and sporadic rainfall.
Historically, the Pronghorn inhabited southwest Arizona and the northern part of Sonora, Mexico. Specifically, the Sonoran pronghorn was thought to inhabit from Hermosillo to Kino Bay in Mexico, to Highway 15 to the east, to Altar Valley and the Tohono O'odam Nation to the north, and to Imperial Valley, California, to the west.1 Presently, a small population of antelope survive in the arid flatlands of southwestern Arizona and Mexico.
Does are ready to mate at 16 months and bucks are ready by one year of age. The Sonoran pronghorn breed from July through September.2 Gestation is about 245 days. At birth, fawns weigh from five to seven pounds.
The Sonoran pronghorn feeds on herbs, cacti, and desert grasses. Similar to cows, the pronghorn has a rudiment stomach, or a four-part stomach. This is especially beneficial to the antelope because it allows for the digestion of roughly textured foods (cacti and other desert plants) and allows for a high level of water retention.
The Sonoran pronghorn has been listed federally endangered since June 2, 1970.
Sonoran Antelope in Pima County:
Only two groups of Sonoran pronghorn species remain: one in Sonora, Mexico, and one in Arizona. The current distribution of pronghorn in Arizona lies predominately in Pima County. The antelope's present range lies in the Barry M. Goldwater Range, Organ Pipe Cactus National Monument, and Cabeza Prieta National Wildlife Refuge, with occasional sightings in Bureau of Land Management lands.3 The Sonoran pronghorn numbers are very low, with only 150 (estimated) in Arizona, and 250 (estimated) in Mexico. The possibility of A. a. sonoriensis extinction looms near if adequate protection and planning is not implemented. U.S. Fish and Wildlife has developed a Sonoran pronghorn recovery plan, with the goal of eventually removing the pronghorn from the federally endangered list.
1. U.S. Fish and Wildlife Service. Sonoran Pronghorn Recovery Plan Revision. August 30, 1994, Albuquerque, New Mexico.
2. Arizona Game and Fish Department. 1998. Antilocarpra americana sonoriensis. Unpublished abstract, Heritage Data Management System.
3. Environmental News Network. November 11, 1998. "Twelve Agencies Face Suit to Protect Pronghorn." ENN Daily News.