US Federal wildlife biologist Mike Coffeen is ecstatic these days. His efforts to save North America’s fastest mammal - the endangered Sonoran pronghorn - are succeeding beyond expectations. Five years after drought whittled the deer-like animal’s population to a handful, pushing it to the brink of extinction, its numbers are back above 100.
Biologists are especially encouraged by the 18 fawns born within the past three months in a square-mile captive breeding enclosure within this sprawling national refuge in southern Arizona - what Coffeen calls “our disaster ace in the hole.” “Eighteen is above what I thought we’d have, so I was ecstatic,” said Coffeen, who is with the U.S. Fish and Wildlife Service. “We’re at a point in this program where we’re on a roll.” The goat-sized pronghorn, which are often mistaken for antelope but are genetically distinct, live only in the harsh deserts of southwestern Arizona and in northern Mexico. Its also the closest living relative t the Baja California pronghorn.
They can run at speeds approaching 60 mph. In 2002, lacking water and forage, the Arizona pronghorn population crashed from nearly 140 to an estimated 21. By the following year, Coffeen and others were hauling water into the desert to try to save the species. “We were within just a few weeks of all of them dying,” he said, but a rare September rain saved the remaining animals. Coffeen said that crisis kick-started the captive breeding program. Animals were put into a pen surrounded by two electrified fences intended to discourage coyotes, mountain lions and bobcats. In dry times, water is piped into the pen to irrigate foliage that pronghorn favor, including shrubs like bursage, chain fruit cholla and mesquite pods. The animals get supplements too: alfalfa, hay and a zoo pellet mix. Shade cloth covering the fencing from inside has succeeded in keeping the frisky pronghorn from running into it at literally breakneck speed.
Everything undertaken aims to avoid human contact and prevent domestication, which compromised a similar program in Baja California, Coffeen said. Fawns caught in the wild were bottle-fed and hand-raised in that program. “One of our primary objectives was to try to raise them as close to wild as possible,” said Arizona Game and Fish Department biologist John Hervert. “They still act like wild pronghorn. They still run away. They’re not domesticated at all.” The pen now holds 43 animals, including the fawns, their mothers, a few adult bucks and several yearlings. The refuge’s wild population was estimated at 74 in December with at least another dozen wild-born fawns sighted since. Coffeen and three Game and Fish employees monitor the enclosure animals daily from an overlooking hill. It will be another 1 1/2 years before the newest pen-born fawns are released into the wild, ready to reproduce.
Coffeen said the Cabeza Prieta can sustain 300 to 500 animals in decent conditions but probably less than 100 in severe drought. The pronghorn recovery plan also calls for establishing a second population in the Kofa National Wildlife Refuge near Yuma. Challenges remain, however. Despite the rebound, the ongoing drought could cause the population to decline again. Habitat remains the core issue, said Jenny Neeley, a spokeswoman for the conservation group Defenders of Wildlife, which has sued the military and federal agencies over their effects on pronghorn habitat. “We’re very pleased with the success of the captive breeding program,” Neeley said. “Our concern is what happens once the animals are released, because the base problem with pronghorn recovery at the end of the day is, Is there enough suitable habitat to support a sustainable population?”
Border-related activity has heightened the threats to the pronghorn. Border Patrol crackdowns elsewhere have funneled illegal immigrant and drug traffic into their habitat on the refuge, which shares 56 miles of border with Mexico, Neeley said. “The border issue is the issue that is threatening the pronghorn the most,” she said, citing migrants, vehicles, vehicle barriers, roads and other infrastructure. Baja Safari Editorial: Neeley clearly is a fuzzy headed liberal. The pronghorn greatest threat now is its genetic pool challenges, not the border and the border patrol.
A die-off in the wild, and the severity of one, will depend on whether there are normal summer rains, said Hervert, the Game and Fish Department biologist. Keeping the penned animals alive and healthy will be essential, officials said. Toward that end, captive-born fawns are being kept at least another year to become stronger and more mature before release. “We’re going to have a setback at some point,” said Hervert. “But we have a safety net. Though the population could reverse and decline, we don’t expect that it could ever decline to the point that we saw in 2002.”
