Urban Sprawl Squeezes Pronghorn Antelope Out

By Laurel Morales
March 31, 2014
Laurel Morales
A housing subdivision, a golf course and roads are named after the antelope that have been squeezed out by development.

When we think of the West, we picture wide open spaces. But roads, new homes and commercial buildings have cut across those spaces. And that development is having an impact on the pronghorn antelope, especially in one of the fastest growing areas in the Southwest — Prescott Valley in northern Arizona.

Jim McClasland has lived in Prescott Valley for more than five decades. And he’s watched it change from his front porch.

"If you stand here and look, you can see there were no buildings, no people," said McClasland, the retired Parks and Recreation director. "It was just wide open country."

And thousands of pronghorn antelope were free to roam. Today the valley is packed with houses and strip malls. When McClasland bought a house he decided to live on the outskirts of town to enjoy the wildlife.

"But at the same time I took habitat," McClasland said. "And I consciously knew that I was doing that, but I also consciously did not put up a fence. This fence that my neighbor has affects movement of wildlife. It just does but yet people don’t want javelina in their backyard tearing up flowers."

Laurel Morales
Jim McClasland has been watching the pronghorn herds decline in the Prescott area for more than five decades.

I took a drive with the Arizona Game and Fish Department's Virginia Gouldsbury and Zen Mocarski. They showed me how those fences fragment pronghorn habitat. We drove beyond the fences to where we hoped to see antelope. I had my camera ready.

We had trouble finding them. It’s fawning season, so many females are bedded down ready to have their babies. But there are also fewer antelope here today. Researchers once estimated 5,000 antelope in this area. Today there are only about 1,000 in Prescott Valley.

We drove past a subdivision called Pronghorn Ranch. I asked if that's ironic.

"It will be ironic if it all gets developed and there’s no pronghorn out here," said Gouldsbury, the area's wildlife manager. "But 20 years ago it was used as advertisement by a lot of the developers to say ‘come live with the pronghorn’ and a lot of people moved here for it."

The antelope are unique. They’re the fastest animal in North America. They can maintain speeds up to 60 miles per hour. But they’re also very high strung. The idea of crossing a road overwhelms them. When Game and Fish has tried to relocate pronghorn, Mocarski said a few typically suffer what’s called capture myopathy.

Laurel Morales
Prescott Valley has been growing at a rapid rate for the last 30 years. Fences, roads and housing developments have fragmented herds and put up barriers that make it difficult to survive.

"For a human it would be similar to a heart attack," Mocarski said. "They just over-stress. And their heart begins to beats so fast and it stops."

The agency uses helicopters and corral traps, which are large tarps that surround a group of animals. Mocarski said they’re designed to minimize stress.

Back in the early 90s Prescott developers built a subdivision where a large herd of pronghorn lived. Game and Fish tried to relocate some of the animals. A few died in the process. When people found out, they protested. Mocarski says Game and Fish backed off but warned that without relocation, the entire herd would die a slow death.

"It took less than a decade for that herd of 129 to go from 129 down to 100, down to 90, down to 50 to the point today where there are zero," Mocarski said. "There are none left. And It just proves the do-nothing approach doesn’t work."

He said antelope died for several reasons. The animals’ primary defenses are their tremendous eyesight and speed. They need wide open grassland to see a predator coming. When antelope are confined to a small space, inbreeding becomes a problem.

"One of the things I hear a lot ‘why do you all interfere with wildlife why don’t you just leave them alone?’" Mocarski said. "I understand what they’re saying but they need to understand the bigger picture."

Mocarski said human development is the number one cause of wildlife extinction in the world.

Laurel Morales
Zen Mocarski is the information and education program manager for the Game and Fish Department in northwestern Arizona.

"We’ve already interfered with wildlife," Mocarski said. "If we want our children and our children’s children to see the same animals and the same diversity that we get to see today then we have to manage wildlife."

This winter, Game and Fish relocated eight antelope from this area. Volunteers in southern Arizona removed almost 4,000 acres of mesquite and modified 50 miles of fences so the reintroduced antelope could crawl under them.

Across the state researchers are also working on building wildlife corridors over roads and through private land so the animals aren’t so confined.