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Cabeza Prieta Natural History Association
Sonoran Pronghorn
(Antilocapra americana)
News Release

Crater Range


Sonoran Pronghorn - News Release
by David Eslinger

For Release: March 5, 2005

Endangered Pronghorn Births Signal Success

North America's fastest land animal, the endangered Sonoran pronghorn, is beginning a comeback as five fawns, including two sets of twins, were born in late February and early March on the Cabeza Prieta National Wildlife Refuge near Ajo, Arizona.

Sonoran pronghorn recovery team leader Mike Coffeen said "We are really excited by these births. We've felt like expectant fathers for some time, and we are proud to have been instrumental in improving the future chance of recovery for the species. All the fawns appear active and alert, and seem to be thriving in their environment."

Female pronghorn usually give birth annually after they reach two years of age, and separate from the herd to give birth to one or two fawns from March to May. The young weigh four to twelve pounds at birth and are about 15" tall. Within a day or two the young can sprint at speeds up to 25 miles an hour. Mortality is high, with about 40% dying by mid-July due to stress and predation. Pronghorn are estimated to live nine or ten years on average, and to twelve years in captivity.

For several years the U.S. Fish and Wildlife Service, Arizona Game and Fish Department, Mexican wildlife authorities and many supporting agencies, organizations and volunteers have worked diligently to recover the Sonoran pronghorn and build the population for eventual release into suitable habitats in Arizona and Sonora, Mexico. A program for capturing and relocating animals began several years ago, with the initial captures in December, 2003. Additional captures in the United States and Mexico has brought a total of seven animals to the refuge. The capture of four pregnant females in December of 2004 provided a significant source of future breeding stock. This capture-breeding-transplant action is considered essential to the survival and recovery of the Sonoran pronghorn. A total of twelve animals are now in the large, predator-proof enclosure, and hopes are for additional births this spring.

The Sonoran pronghorn population has declined drastically in the last century due to habitat loss, unregulated hunting in the early 1900s and natural causes. In the spring of 2003, surveys showed the United State's population of Sonoran pronghorn had dropped to only 18 animals following a series of unusually dry years in which few fawns were born and fewer survived. The Sonoran pronghorn is now one of the most endangered mammals in the world. The Sonoran pronghorn population in Mexico, though larger than that in the U.S., is still endangered, and will help form the basis for this effort through ongoing international efforts to preserve this valuable species.

The project is based in part on a successful captive-breeding program developed by Mexican biologists to help the related but also endangered peninsular pronghorn in Baja California.

The Sonoran pronghorn was originally listed as endangered in 1967 under the Endangered Species Preservation Act. Endangered species status means that a plant or animal is "…any species which is in danger of extinction throughout all or a significant portion of its range." A recovery plan for the animal has been prepared, but the recent severe drought conditions have worsened the animal's chance for survival without the current management actions.

Cabeza Prieta National Wildlife Refuge was established in 1939 to help protect dwindling populations of desert bighorn sheep. Today Refuge management focuses on the Sonoran Desert ecosystem and its wildlife.

The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System that encompasses nearly 540 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 64 fishery resource offices and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.



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Natural History of the Sonoran Desert and Refuge