Captive breeding is a wildlife management tool of last resort, and it's not an action any wildlife manager chooses lightly or often. It can be difficult, expensive, and rife with risk. But when so few animals are left, we and our conservation partners must do whatever it takes to prevent extinction.
That's why we've developed the captive-breeding program for the Sonoran pronghorn.
It began over the winter of 2003-2004 when seven of the remaining animals were captured and placed in a specially constructed, one-square-mile pen on Cabeza Prieta Refuge.
In the captive-breeding pen, one carefully selected buck breeds with all of the herd's does. Breeding bucks are rotated to ensure as much genetic diversity as possible.
Jim Atkinson has been the Sonoran pronghorn recovery coordinator since 2008.
In the future, Atkinson said, breeding bucks may be brought in from one of the Mexican populations "to mix up the genetics and ensure the population stays robust."
A Sonoran Pronghorn doe. (Photo: USFWS)
But, he added, "We're not going to be in the captive-breeding business forever. The whole goal of our efforts right now is to put a floor under this herd and keep it from cratering again and again. For now, we can focus on restoring the herd and stabilizing it for the long haul." Other habitat enhancement efforts are essential elements of a broader effort to recover the pronghorn.
Along with Arizona Game and Fish, primary partners in the recovery effort are the National Park Service, U.S. Air Force, U.S. Marine Corps, and the Bureau of Land Management. Many others support specific activities, such as professionals at the Phoenix and Los Angeles zoos who share their expertise in captive breeding.
Recovery partners developed several adaptive management measures after the pronghorn plummeted in 2002. Central to their success is the establishment of a second U.S. population so that the sub-species is less vulnerable to a catastrophic event that would put it back on the brink of extinction. Kofa National Wildlife Refuge, about 90 miles northwest of Cabeza Prieta Refuge and historically part of the Sonoran pronghorn's range, was the chosen location for the second U.S. population.
Since 2006, almost 100 captive-bred pronghorn have been released to supplement the original U.S. population, all within the current range, including areas of Cabeza Prieta Refuge, Organ Pipe Cactus National Monument, and the Barry M. Goldwater Range East (Air Force) and West (Marine Corps). The first pronghorn to establish the second population on Kofa Refuge were released just recently—returning the pronghorn to a part of its range it hadn't inhabited for more than 100 years.
That momentous event occurred in January 2013, when nine pronghorn fitted with GPS collars were taken by helicopter from Cabeza Prieta Refuge to their new home on Kofa Refuge. They were released into the King Valley, in an acclimation area within a half-squaremile breeding pen, so they can be monitored prior to their full release.