The Big Story: Recovery program for pronghorn working

CABEZA PRIETA NATIONAL WILDLIFE REFUGE, Ariz.— 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 pronghorn population to a handful, pushing it to the brink of extinction, the animal’s 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.”

Live only in area

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. They resemble deer and 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.

Animals were put into a pen surrounded by two electrified fences intended to discourage coyotes, mountain lions and bobcats.

West of Tucson

The site in a valley more than 130 miles west of Tucson was chosen to minimize the chances that drug and immigrant smugglers would drive through the enclosure while crossing the refuge to sneak contraband into the country.

Money and other assistance was cobbled together from Fish and Wildlife funds and partnering federal agencies—the Marine Corps, Air Force, National Guard, National Park Service and Bureau of Land Management, all prodded by a lawsuit.

In dry times, water is piped into the pen to irrigate forage that pronghorn favor, including shrubs like bursage, chain fruit cholla cactus and pods on mesquite. 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.

Avoid human contact

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.

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.