PRAIRIE GHOSTS

BY: MATT JAFFE

THEY WERE DYING. One by one, the last Sonoran pronghorns in the United States were succumbing to a devastating drought that desiccated Southwestern Arizona in the summer of 2002. A distinct subspecies genetically and geographically, the population of Sonoran pronghorns was in full collapse - not just fawns and the older, weaker members of the herd, but healthy adults in their prime, animals strong and well adapted to the cycle of hard times in the desert. Only 21 Sonoran pronghorns survived.

For more than 30 years, John Hervert, wildlife program manager with the Arizona Game and Fish Department in Yuma, has studied Sonoran pronghorns, which have been on the endangered species list since 1967. Through the 1990s, Hervert watched as the number of animals declined, especially during a drought between June 1995 and August 1997. But 2002 was something else entirely.

"It was a historic drought," Hervert says. "Climatologists say it was comparable to a drought that Arizona experienced 1,400 years ago. Widespread and long-lasting. So these animals basically starved to death. We were able to document that because we were monitoring them with radio collars and frequent flights. It was a very agonizing time, because we could see that this population was going to go extinct. And there was very little we could do about it."

While bison are a national icon, Sonoran pronghorns are part of an even more purely American family of animals. Classified in the family Antilo capridae, they're one of five pronghorn subspecies, all of which, unlike bison, live exclusively in North America. Pronghorns resemble and are colloquially referred to as antelopes, and the animals depicted on the famous Antelope House petroglyph panel in Canyon de Chelly are actually pronghorns. But they're most closely related to giraffes.

Sonoran pronghorns are uniquely adapted for their arid environment in Arizona's Lower Colorado River Valley and upland areas of the Sonoran Desert. During periods of good rains, the desert sprouts into a veritable buffet for the herds. Opportunistic eaters, Sonoran pronghorns feed off more than 250 different species of plants, from mesquite beans and ocotillo leaves to highly nutritious forbs such as buckwheat, as well as chain fruit chollas, an important water source.

"They'll eat everything out there, other than creosote," Hervert says.

Even so, they're shaped by scarcity, not abundance. When the monsoon storms don't arrive, desert plants may survive but drop their greenery, leaving little forage for the animals. So Sonoran pronghorns are smaller and thinner than other pronghorn subspecies. What's most noticeable, Hervert says, is Sonoran pronghorns' much narrower necks, a reflection of the animals' reduced body mass.

It's unknown whether Sonoran pronghorns ever roamed the desert in large numbers, but Hervert says preliminary field investigations have estimated that it takes around 1 million acres to support 80 to 100 of the animals. "That's a very low number for such a large area," he says. "And in the modern era, the Sonoran pronghorn has alwaysbeen rare. Very rare.

At one time, the population of the different North American pronghorn species reached an estimated 35 million, with a distribution from southern Canada to near present-day Mexico City, and from the Mississippi River to the Pacific Ocean. With the country's westward expansion, hunting, farming and other human activities took a heavy toll. By 1915, only 13,000 pronghorns remained.

Now, the overall pronghorn population is back up to around 800,000. Thanks to the intervention of wildlife agencies and a successful captive breeding program, Sonoran pronghorn populations in Arizona have rebounded from near-extinction. But even including the larger herds in Mexico, they represent a tiny fraction of the total pronghorn population: just 1,100 animals.

On A BREEZY EARLY-AUTUMN MORNING, I head out from Ajo and into Cabeza Prieta National Wildlife Refuge with Jim Atkinson, wildlife biologist with the U.S. Fish and Wildlife Service. The refuge together with Barry M. Goldwater Air Force Range, Organ Pipe Cactus National Monument and a block of Bureau of Land Management land - protects the heart of the Sonoran pronghorns' territory in Arizona. Add it all up, and there's more than 2 million acres.

"It takes you pretty much to Interstate 8 and all the way to Yuma," Atkinson says. "This is a big piece of classic, unfragmented Sonoran Desert landscape."

Atkinson grew up in Virginia. From an early age, he says, he was "wired for wildlife." His interest began with whatever showed up in his backyard before he and his brother began ranging farther afield to hunt and fish together. They eventually built a cabin on land the family owned."

"Everyone else was going to games and dances and stuff. We would grab a chain saw and all of the gear and cut wood," he says. "They all wanted to be the top 0.1 percent [who become] sports stars or rock stars, or be a military guy, or whatever. I quickly realized, Eh, I don't have any aptitude for all of that other stuff. So it's this. This is how it's always been for me."

During his more than 30 years of wildlife work, Atkinson has focused on birds, fisheries, whitetailed deer and black bears. The opportunity in 2008 to come to Arizona and join the Sonoran pronghorn effort was a departure after his decades in Washington state and Virginia.

Awareness of the animals: Gila monsters, rosy boas and all of the desert birds. It's so different than everywhere else. From a biologist's perspective, that's pretty exciting. To get a chance to be in a place that's totally new [and] that's radically different from what I grew up with. For me, the Sonoran Desert was like going to another planet. It's a landscape by Dr. Seuss.

Atkinson eases the truck down the rough road, bound for the 1-square-mile breeding pen for Sonoran pronghorns. Bouncing along, it's steady but slow going, and Atkinson brings me up to speed on the animals' recovery.

If not for the return of rains in September 2002, the 21 surviving Sonoran pronghorns in Arizona would have perished. After nearly losing these last few animals, wildlife officials realized a largely hands-off approach - and the assumption that, given enough land, the subspecies would endure needed to be reconsidered.

Atkinson says a decision was made to try to “put a floor under” the Arizona population to prevent another crisis. The first captive breeding pen began operations in 2003, and a system of water catchments was established across the desert. But the recovery effort faced inherent challenges. Because bearing and raising young is so energy-intensive, Sonoran pronghorns give birth only once every other year. And the mortality rate is high.

“Fawn crops come and go. Some years, they die; some years, they do real well,” Atkinson says. “But it's that core group of adults. If we have a poor year and all the fawns die, we still want to have a breeding population.” With herds in Arizona and Sonora, Mexico, Sonoran prong-horns are an animal of the borderlands. They share their habitat with migrants and drug smugglers cutting across the desert, as well as with the members of U.S. law enforcement, including border and customs agents, charged with stopping the human flow.

We cross a wash where a tattered blue flag marks a large water tank part of a network of aid stations established to reduce the number of deaths, especially during summer months. Black 1-gallon jugs, evidence that people have passed through, are scattered in the wash.

For Atkinson, the cross-border traffic adds a dimension to his wildlife work. His encounters have been minimal mostly chance meetings with desperate, thirsty people who decided to turn themselves in. He acknowledges that there are “some pretty hardcore dudes packing serious weapons,” but he doesn't carry a gun, because he's not in a law enforcement role. Although he's not especially afraid, Atkinson makes a point to stay in the open and close to his truck: “I keep my head on a swivel.” He adds, “We've probably been under surveillance of some sort since we left town. There are always people up in these hills, watching. They know what you're doing, and they're communicating with each other. They're not trying to get you. They're trying to avoid detection.” AFTER ABOUT 40 MINUTES, we reach the pen. While three wild herds live in Arizona, wildlife agencies maintain this large enclosure as part of their breeding program, which is designed to stabilize the Arizona population, meet recovery goals and provide animals that can be sent to Mexico to promote genetic diversity. It's one of two in the state: A second breeding pen was established in 2011 at Kofa National Wildlife Refuge, northeast of Yuma.

The 80 Sonoran pronghorns in the pen live a largely natural existence. They forage off the land but receive supplemental water and food as needed. A double electric fence capable of delivering 7,000-volt jolts to keep out mountain lions, coyotes and bobcats surrounds what Atkinson dubs “a mini-Jurassic Park enclosure.” We climb a short trail to a viewing station basically, a pair of folding chairs inside an enclosure covered by shade cloth. The Growler Mountains rise in the distance, and Atkinson quickly picks out a few animals moving along a wash near saguaros and mesquites. They're difficult to see. Lighter in color than other pronghorn species, these animals easily blend into the tawny terrain. Soon, we're able to pick out 15 to 20 of the pronghorns moving in a loose, single-file line before bedding down for the morning in the shade.

I'm surprised by how calm the animals have remained. Hervert had mentioned that aircraft flying at 1,000 feet can scare herds, and Atkinson says the animals are always alert, with eyes and ears that poke out above the scrub like a submarine's periscope. Sonoran pronghorns can spot movement from distances of up to 7 miles. And when they spook, they and the other subspecies earn their nickname: “prairie ghosts.” Pronghorns are North America's fastest land animal and the second-fastest in the world, behind only cheetahs. Their speed likely is an evolutionary response to a Murderers' Row of decidedly fantastic beasts that once roamed the continent, including packs of hyenas, dire wolves, huge lions 25 percent bigger than today's African lions, and especially the now-extinct American cheetahs.

These primordial cheetahs, like their present-day African relatives, could outrun a pronghorn in a sprint of several hundred yards. But pronghorns can reach almost 60 mph for a short distance, then settle into a steady pace of 45 mph for several miles by which point they would have left cheetahs, and any of those other predators, literally in the dust.

Because monsoon rains can be highly localized, the animals often need to reach areas with recent moisture and fresh vegetation. They range freely, covering 15 miles on some days and exploring more than 1,000 square miles in a year. While the government lands in Arizona seem expansive, Sonoran pronghorns are cut off from parts of their historical range, much of which has been altered. They once depended on the Gila River and Mexico's Rio Sonoyta, but, as Hervert told me: “Those rivers are largely gone now, and the animals exist in a very fragmented landscape.”Reluctant to cross roads, they're hemmed in by I-8 to the north. In stretches where there's only a vehicle barrier along the border, Sonoran pronghorns can crawl underneath as athletic as they are, they don't like to jump. How a proposed border wall could affect their movement is hard to know until a specific design is chosen. But once across the border, the animals almost immediately face Mexico's Highway 2, which cuts them off from two separate herds in Sonora: at El Pinacate and Gran Desierto de Altar Biosphere Reserve, and in the Quitovac area.

It takes a rare animal to surmount these obstacles. Atkinson tells a story about five bucks that were collared and released. One ended up on the Air Force range and survived. Four went north, toward Gila Bend, where three drowned in a canal. A lone survivor continued west.Trackers lost him for around eight months, until a surveillance flight over the Pinacate spotted a collared animal. The crew downloaded the collar's information, and a map showed Atkinson explains how the animals are slowly conditioned, over a couple of months, to enter and feel safe in the enclosures. The food is moved deeper and deeper into the bomas, which are 50 feet across and 12 feet tall. Shade cloth covers the sides, and after a while, the animals relax in the corrals.

On the day of the roundup, a remote-controlled gate is trig-gered and closes behind the pronghorns. Atkinson points out the tower where he waits. "You have 40 animals, within 100 yards of you, that have the best eyesight and some of the best hearing out on the desert," he says. "And you can't do anything that's going to get their attention. One little foot shuffle. You blink wrong. Because they'll panic, and you'll see the white hair on their rump flare like a signal. And they're gone."

The goal is to pick out the best animals for release - usually 2-year-olds that are robust and most likely to survive on their own. After being netted, the animals are tagged and receive vaccinations, as well as a mild sedative to reduce stress. Atkinson likens the process to an assembly line that moves the animals from the corral traps to air-conditioned trailers for transport.

The animal had covered more than 100 miles, including several crossings of Highway 2 in Mexico, before he at last found the Pinacate herd.

"That's the most extreme case we've documented of long-range movement by an individual who had nobody to join up with and couldn't find a herd," Atkinson says. "And he lucked into a herd because he finally happened to go in the right direction. Otherwise, he could have wandered off into never-never land. He probably wouldn't have made it. A lone pronghorn is vulnerable. They need all of those other eyes and ears in the herd."

EACH DECEMBER, wildlife officials, biologists and veterinarians convene at a trio of connected bomas, an African name for livestock enclosures. These circular corral traps in the breeding pen are used to hold the Sonoran pronghorns so select animals can be captured and taken to other locations.

"There's a lot of kinetic energy when you've got three pronghorns in a capture cell and 15 people in there, all bouncing around together," he says. "Had broken noses, bad bruises and cuts. We've had dead pronghorns because they collided with each other. It's always an uncertain outcome. But we've had years when we've handled 100 pronghorns with no problems at all. We've gotten really good at what we do."

The stakes are high. So is the satisfaction. For Atkinson, Sonoran pronghorns gave him the chance to get beyond doing inventorying and monitoring a chance to have a direct, measur-able impact on the long-term survival of a crea-ture on the brink.

"We get people coming into the office who have been out on this road, saying, 'You know, we saw eight of those pronghorns. Right off the side of the road,'" he says. "You could see that light on their faces. Like they've seen something pretty spectacular. And they have."

When I speak with Hervert, he's briefly back on the ground between aerial surveys of desert bighorn sheep in the Kofa Mountains. Hervert grew up in Tucson but admits he'd never heard of Sonoran pronghorns until moving to Yuma. Nobody talked about them. Little was known.

Saving Sonoran pronghorns has benefits, both for the public and for future scientists who will study them with an array of tools that currently don't exist. But there's more to the prong-horns' survival than that. "It's a deep philosophical question," Hervert says. "I just don't think we've done our job very well if we see the extinction of a species. Especially when we have the opportunity to make such a difference."

EDITOR'S NOTE: Since the reporting of this story, Jim Atkinson has retired from the U.S. Fish and Wildlife Service. AH