December 18, 2006
First Release of Sonoran Pronghorn Antelope
First-ever captive-bred Sonoran pronghorns released into the wild
The endangered Sonoran pronghorn received a historic helping hand on Nov. 19 when the first-ever captive-bred bucks of this nomadic desert breed were released on the Cabeza Prieta National Wildlife Refuge in southern Arizona near Ajo.
Two yearling males, which were born in captivity last year in a 640-acre breeding facility at the refuge, were released into the wild.
"This release from the captive-breeding enclosure on the refuge marks a historic moment in the recovery of this important cross-border species. With this first-ever release we move one step closer to restoring a free-roaming U.S. population," said Larry Voyles, the Arizona Game and Fish Department's Yuma regional supervisor.
The U.S. population of Sonoran pronghorn was nearly lost in 2003, plunging to only 21 animals, following unusually dry years in which few fawns were born and fawn survival was low. Adult mortality was estimated at 80 percent in 2002, and only one fawn was known to survive that devastating drought year. The wild U.S. population is estimated to be 100.
In response to dwindling Sonoran pronghorn numbers, a captive breeding program was initiated in 2002 on the Cabeza Prieta Refuge. This past spring, 10 Sonoran pronghorn were born in captivity. Habitat improvements, predator control and careful monitoring of the animals in the breeding facility enhanced pronghorn survival.
Sonoran pronghorn were listed as endangered in 1967. The U.S. population has been affected by habitat fragmentation, lost of perennial rivers, and extreme drought, among other factors.
North American pronghorn are the fastest land animal in North America, with speeds recorded up to 60 mph. They have extremely keen eyesight, with an eye size comparable to elephants. Their eyes are set high on the sides of their head, giving them a field of view of almost 300 degrees. Their speed and eyesight are their main defenses against predators.
Sonoran pronghorn, which are a subspecies of North American pronghorn, are nomadic desert animals that are typical of desert-dwelling mammals, such as the Oryx of the Serengeti Desert or the Dorcas gazelle of the Sahara . A typical Sonoran pronghorn may range over 1,000 square miles in a single year.
The continuing recovery of these nomadic desert animals is the result of a hands-across-the-border cooperative conservation effort involving federal, state and Mexican agencies, organizations and volunteers.