Wild horse population crisis: Birth control with PZP or roundups by the BLM.

Wild Horses Are Symbols of Freedom, but They’re Also Invasive Pests

Wild Horses Are Symbols of Freedom, but They’re Also Invasive Pests

The state of the universe.
April 16 2014 11:49 PM

Wild Horse Crisis

What’s the best way to control an invasive species: Round them up or shoot them?

a group of wild horses.
Ada Inbody (left) and Patricia Hatle walk toward a group of wild horses near Cody, Wyo. Inbody and Hatle control the horse population near Cody using a dart gun loaded with birth control vaccine.

Courtesy of Warren Cornwall

MCCULLOUGH PEAKS, Wyo.—The view from the wind-blown hillside 20 miles east of Cody, Wyo., looks like something from a Hollywood Western. Sixteen wild horses graze among the sagebrush, framed by a backdrop of parched buttes painted ochre and tan. Nearby, two figures in brown work pants and long-sleeved Western shirts squint into the distance. One has a rifle slung over the left shoulder.

The unarmed member of the duo, Patricia Hatle, turns to me and says, matter of factly, “Well, let’s see what we can do.” It’s time to go shoot horses.

A crisis can make for drastic measures. And the country’s effort to rein in the West’s wild horses is in crisis. Armed with dart guns loaded with a birth-control vaccine, horse lovers, scientists, and feds like Hatle, who works for the U.S. Bureau of Land Management, are trying to shoot their way out of the problem.

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Folks far from the deserts of the mountain West might wonder why anyone is worried about wild horses. The animals have attained a mythic status as symbols of freedom and the Wild West, portrayed in everything from paintings to DreamWorks’ cartoon movie Spirit.*

a herd of horses in the desert east of Cody, Wyo.
Patricia Hatle (right) scans a herd of wild horses in the desert east of Cody, Wyo., as Ada Inbody waits to get close enough to dart one of the mares with a birth control vaccine.

Courtesy of Warren Cornwall

But a majestic icon can also be a four-legged pest. Today’s horses are an invasive species, introduced to the Americas by Europeans. Left unchecked, they overwhelm fragile desert ecosystems by chomping too much of the greenery to stubble. And they compete for the grass with another invader that has more economic clout: cattle.

For much of the 20th century, ranchers and the federal government dealt with wild horses by shooting them or hauling them to slaughterhouses. That all changed in 1971 when Congress passed a law saying the government should protect and manage the animals. Since then, the BLM has been stuck on a horse-powered hamster wheel. To keep the population in check, the agency periodically corners horses using helicopters and then ships them to permanent horse farms. Some get adopted. Many spend the rest of their lives there. The roundups anger horse advocates, who say they traumatize the animals. And it has a fatal flaw. As soon as the horses are carted off, the remaining ones start breeding again.

The situation has grown so grim that the status quo is impossible. The government has nearly 50,000 horses in captivity at a cost of $46 million a year, wild horse adoption rates are low, animal welfare groups are calling for fewer roundups, and ranchers are suing for more. “Our backs are against the wall,” said Tom Gorey, a BLM spokesman.

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A decade ago, Hatle was caught in this familiar cycle. In 2004, the BLM rounded up 362 horses, leaving approximately 85 in the McCullough Peaks, 110,000 acres of arid foothills, mountains, and barren badlands east of Cody. The removal of much of the herd—a tourist attraction and source of local pride—concerned Cody horse fans. They formed a group, Friends of a Legacy, and started urging the BLM to find another way to handle the horses.

One leader of FOAL is Ada Inbody: Hatle’s rifle-toting partner who today works with Hatle and the BLM to control the horse population.

The technique they use was developed by Jay Kirkpatrick, an expert in reproductive physiology from Billings, Mont., who has become a pioneer in chemical contraceptives for wild animals. The nonprofit he founded, the Science and Conservation Center, manufactures porcine zona pellucida vaccine. It’s a vaccine made from pig ovaries that causes an immune reaction blocking an animal’s eggs from being fertilized. PZP has been tried on everything from African elephants to deer. Kirkpatrick has used the vaccine for 19 years to control horse populations on Assateague Island, a federal wildlife refuge off the coast of Maryland.

Hatle experimented with vaccinating horses with PZP between 2004 and 2009. Then, in 2011, with FOAL paying for the PZP and providing her with a sidekick, she picked up her gun and started darting horses full time.

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Shooting a skittish wild horse in the butt using a gun with a maximum range of around 60 yards isn’t easy. And the current PZP formulation requires a booster shot every year. But Hatle and Inbody seem happy spending their days roaming the hills and gulches in search of their quarry.

Hatle grew up riding horses in Riverton, Wyo. She has four adopted wild horses. Inbody showed up for the hunt wearing horse-shaped earrings and a silver necklace with a herd of charging mustangs. At home, she has two horses, including a wild horse she adopted that has a broken hoof bone. The horse gets monthly visits from a massage therapist. The 76-year-old great-grandmother is also a crack shot. Several years earlier, she brought down an antelope from 350 yards away with a single bullet.

This July day, Inbody is the designated shooter. Their target is a black mare with white around its hind ankles named Dazzle. We stroll downhill, skirting patches of prickly pear cactus.  When we get within 100 yards of the horses, I hold back with a BLM minder while Hatle and Inbody try to get close enough for a shot.

dart gun used to dart wild horses with a birth control vaccine.
Ada Inbody demonstrates her shooting technique with a dart gun used to deliver a birth control vaccine to wild horses.

Courtesy of Warren Cornwall

As they approach Dazzle, Hatle stops and unfolds a tripod to steady the rifle. The horse casually walks out of range. The two women pack up again and continue their pursuit. For the next 30 minutes, the two parties are caught in a slow-motion dance—the humans gently chasing, the horse nonchalantly keeping just out of reach.  Hatle and Inbody finally surrender. “Well, it’s just like a normal day,” Hatle said as she returned. “You just have to keep trying. It’s patience and persistence. It’s not easy.”

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But it has paid off. The number of newborn horses has dropped from 47 in 2009 to 16 in 2013. Hatle hopes from now on she will only need PZP—rather than roundups—to keep the herd size below 140.

Despite this apparent success, the BLM hasn’t exactly embraced PZP. It’s being used on just 13 out of 179 herds managed by the BLM. Many herds are so wary of people or in such remote areas that darting every year would be next to impossible, said several officials. “A lot of places, I just don’t see how it would work,” Hatle said.

But it’s also driven by the agency’s money woes. The number of horses treated with PZP fell by half between 2012 and 2013—down to 509—a tiny fraction of the estimated 34,000 wild horses on BLM land. The BLM cut its PZP use to pay for housing more horses and to cope with a $3 million budget cut. Now the BLM is hoping to find salvation in a yet-to-be-invented vaccine that lasts longer than PZP. It has $1.5 million earmarked for the effort.

The hesitation is maddening for Kirkpatrick and some wild horse advocates. They say the BLM suffers from a reluctance to innovate and an addiction to roundups. The BLM could save tens of millions of dollars if it would capture more mares than it plans to take into captivity, vaccinate them with PZP, and then let them go, according to a 2013 study in the Journal of Zoo and Wildlife Medicine.

This debate roils unnoticed by much of the public, which is more interested in just watching the pretty horses. As we drive back down the dirt track toward the highway, we stop for a chat with Debbie Sprague and her husband, Rick. They sit in lawn chairs in the back of their Dodge pickup, camera at the ready. The two are on vacation from Franksville, Wis., and they’ve come for a taste of the West.

“It’s beautiful out here,” says Debbie Sprague. “I love seeing the wild horses, just seeing them in their natural habitat. It’s part of the West. It’s the way it should be.”

Correction, April 17, 2014: This article originally described the movie Spirit as a Disney production. It was made by DreamWorks.