Wild Horses: Contraceptive Darts and the Fight to Preserve the West

Josie, a buckskinned mare that roams the Book Cliffs in Colorado, had given birth every year from 1996 to 2003. First, there was Joker. And then came Classy, Teardrop, Jolene, Gunshy, Jolie, Haywire, and an unnamed colt. All but one were removed from the range, with federal taxpayers picking up the tab.

Josie was spared the ravages of having that ninth foal by a retired teacher named Marty Felix. A volunteer with the nonprofit Friends of the Mustangs, Felix crawled on hands and knees through sagebrush and around juniper pines to sneak within 40 yards of Josie and shot her with a 4-inch fertility dart. That was in April 2003.

"It's been 10 years since she's had a foal," Felix, 65, said during a recent visit to the range northeast of Grand Junction. "She's 22 years old and she looks like she's 10. She looks fantastic!"

Josie, a wild mare from the Little Book Cliffs herd in western Colorado, had eight foals before range managers treated her with PZP. Foaling stopped, saving taxpayer dollars and likely extending her life. Photo courtesy of Marty Felix.

Josie is just one of about 40,000 wild horses roaming public lands in 10 Western states. Her story is one the Bureau of Land Management, horse advocates, ranchers, lawmakers, and taxpayer watchdogs are hoping the agency can replicate as the cost of managing the nation's wild horses spirals out of control.

Forced by federal law to maintain herds in a "thriving natural ecological balance" with Western rangelands, BLM has gathered and removed more than 100,000 wild horses over the past decade, with more than half of them sent to government-funded holding facilities, a strategy almost everyone agrees is unsustainable.

This year, BLM is spending 60 percent of its $75 million wild horse budget to feed and care for horses in captivity, up from 46 percent in 2000. The number of animals in short- and long-term pens has risen to 50,000, up from 30,000 in 2008 and 10,000 in 2001.

Those numbers are expected to grow amid a sluggish market for horse adoptions that can't keep up with the pace of removals. Wild herds grow at 20 percent annually, doubling in size every four years and tripling every six.

Many experts say the only sustainable solution is an aggressive expansion of fertility control and help from people like Felix.

"It's the only way we're going to get out of this hole," said Holly Hazard, senior vice president of programs and innovations for the Humane Society of the United States, which has partnered with BLM on fertility control projects with Josie's Little Book Cliffs herd and several others. "We can't gather our way out of it. We can't adopt our way out of it."

So far, fertility control is the only management tool that has garnered support from BLM's critics on both sides—ranchers, who fear unchecked herds will compete with livestock for food, and horse advocates, who want BLM to keep the animals on the range.

But in the Little Book Cliffs herd, it wasn't easy to keep Josie from having more foals. Over the next three-and-a-half years, Josie had to be darted five more times by Felix, two U.S. Geological Survey scientists, and BLM range manager Jim Dollerschell.

While the darts themselves are inexpensive—averaging less than $25 a dose—it took significant time and patience just to find Josie on this rugged 36,000-acre high-desert range, let alone get close enough to shoot her in the rump.

BLM officials are cautiously optimistic that the fertility control program here can be expanded to more of the agency's 179 herd management areas, which cover nearly 27 million acres. But many of the herd areas, they note, are too big and rugged—and the horses too skittish—for darts to be used effectively.

"It's enormously challenging, and it's not quite that simplistic," said Dean Bolstad, a senior adviser for BLM's wild horse program in Washington, D.C.

Over the past decade, contraceptive darts have been used on 5,400 wild horse mares in 87 herd management areas, BLM said. Fertility control has also been widely used in the Sand Wash and Spring Creek herds in Colorado, the Pryor Mountains and McCullough Peak herds in Wyoming and Montana, and the Cedar Mountains herd in Utah.

'Miracle'

Little Book Cliffs is a bright spot for the beleaguered BLM horse program. Since 2002, when BLM, the Humane Society, and the Friends of the Mustangs began darting the herd's mares, reproduction has dropped to more than a dozen foals per year—less than 10 percent of the herd's 150 horses.

The drug PZP can be administered by darts (pictured) or through a hand-delivered jab stick. Photo by Phil Taylor.

Gathers have been reduced from once every two to three years to once every seven years, saving significant taxpayer cash and sparing the horses the trauma of being plucked from the range.

Mares here are darted with the drug porcine zona pellucida (PZP), a vaccine derived from pig eggs that changes the shape of receptors on mares' eggs, forcing them to reject sperm. It's about 95 percent effective over the first year.

The drug, which is also used on elephants and wild deer, is widely supported by animal rights advocates because it causes very few behavioral changes. To a horse, getting darted feels like a bee sting. Some will buck and snort after being shot, but within a few minutes, they're back to grazing.

Mares that aren't treated with PZP can be foal factories. One mare in Little Book Cliffs, Belle, birthed 11 foals, eight of which were rounded up and removed from the range. Mrs. Baron, a white mare, birthed 13 foals, a record for the herd, before dying at age 21.

The excess horses are a severe strain on BLM's budget. It costs about $475 annually to keep a horse in long-term pastures and $1,733 annually for each horse kept in short-term corrals. It costs an additional $900 just to round them up.

Very few mares here reproduced once they were put on PZP, Felix said. "It was like a miracle," she added. "They didn't have babies."

Volunteers like Felix deserve much of the credit for the program's success. In 2002, when the PZP experiment began, Felix began learning all of the roughly 150 horses by name, color, and behavioral attributes, recording her observations in notebooks. Felix said she has made more than 1,500 visits to the range.

That expertise comes in handy when BLM decides which mares are due for a dose of PZP and, if a gather is needed, which horses should be removed.

"A lot of this would be cost-prohibitive," said Christopher Joyner, a BLM spokesman in Grand Junction. "When you've got these people locally who have an ownership in the care of the animals, it's a major difference in how we can approach the management of the herd."

For example, BLM will call on Felix this fall when it plans to bait, trap, and remove up to 50 of the Little Book Cliffs horses. For each horse it removes, the agency plans to allow its mother to birth another foal to pass on her genes to the herd, Joyner said. Without volunteers like Felix, it would be nearly impossible to determine which horse that is.

"We have a hard enough time counting the horses," Joyner said. "To be able to go in and tell you the genetic history of individual horses is phenomenal."

But even in this small herd where the horses are relatively tame, applying PZP is labor-intensive. After identifying a mare for treatment, range workers must return to their vehicles to thaw the PZP vaccine and prepare a dart, a process that takes about 10 minutes. Oftentimes when they return, the mare is gone, chased off by an ambitious bachelor.

And after a few PZP treatments, some horses begin to recognize the dart gun. They'll run "like a bat out of hell" as soon as they see it, Felix said. Still, the herd is close to achieving what has eluded BLM at almost every other wild horse area: zero population growth.

'Widespread and consistent' fertility curbs

The National Academy of Sciences released a sweeping two-year study last month that concluded what most have known to be true for years: that the business of removing and warehousing excess horses is "expensive and unproductive" (Greenwire, June 5).

The NAS report recommended "widespread and consistent application" of fertility control, particularly the drugs PZP and GonaCon for mares and chemical vasectomy for stallions.

Those drugs were deemed the most promising when considering their delivery methods, availability, efficacy, duration of effect, and potential physiological and behavioral side effects.

"The committee recommended these approaches based on the evidence of their efficacy with other populations, notably the horses on Assateague Island, but cautioned that scaling up use of these methods to the larger and more disseminated horse populations in the western U.S. will be challenging," said Guy Palmer, a veterinarian with Washington State University and chairman of the study committee.

The fertility control program at Assateague Island National Seashore is considered the most successful wild horse management plan ever achieved, said Jay Kirkpatrick, who directs the nonprofit Science and Conservation Center in Billings, Mont.

The 41,000-acre barrier island off Maryland is home to one of the nation's most famous horse herds, which attracts more than 2 million visitors each year.

Since the vaccine was first applied there in earnest in 1995, herd numbers have stabilized at 114 horses, down from 175 horses. In addition, the health of mares remarkably improved once they were limited to one foal each and spared the stress of pregnancy and lactation.

"Assateague exceeded everyone's expectations," Kirkpatrick said. "The real issue there was not just the technology, but the National Park Service's willingness to take the long view and their ability to stick with the project over changes in superintendents, resource management specialists, et cetera."

But there are unique challenges to replicating the Assateague program in Western herds, he said.

Can treatments be scaled up?

BLM treated about 1,000 mares with the PZP vaccine annually in 2011 and 2012, roughly double the rate of the past six years. But that was still well short of its goal of treating 2,000 horses in 2011 and 2012.

Rojito, a wild stallion in the Little Book Cliffs herd, leads Chablis and Merlot. Photo by Phil Taylor.

BLM's total spending on PZP this year—$660,000 to apply the drug via helicopter gathers and ground darting plus $400,000 for two ongoing research studies aimed at developing longer-lasting PZP vaccines—represents less than 2 percent of its overall wild horse budget.

BLM said that's because its resources are being funneled into removing excess horses as soon as they exceed appropriate management levels—as the law requires—and caring for them. It also must pay for aerial surveys, adoption programs, and other expenses.

But lawmakers and wild horse advocates maintain the agency could do much more. Last month, a bipartisan group of 30 House lawmakers accused the agency of "grossly underutilizing proven, cost-effective and humane alternatives, such as fertility control," that allow more horses to stay on the range (E&E Daily, June 21).

And last week, the American Wild Horse Conservation (formerly American Wild Horse Preservation) Campaign, a coalition of 50 wild horse advocacy groups, accused the agency of "purposefully allow[ing] breeding to continue" at the Little Book Cliffs by not treating enough mares.

"The BLM must begin immediately to manage wild horses on the range," said Neda DeMayo, president of Return to Freedom, AWHC's founding organization. "The federal government has the technology to minimize wild horse removals by managing horses on their rangelands."

According to the NAS study, providing contraception to between 500 and 1,000 mares a year even with a two-year PZP vaccine "will not substantially lower the rate of growth of a population of over 30,000."

"To reduce the population growth rate with contraception, a much higher proportion of the population would need to be treated in a comprehensive, strategic fashion," the report said.

But PZP and other forms of fertility control are harder to employ in Western herds that stretch across as much as a million acres and have up to 10 times the number of horses as the Little Book Cliffs, BLM's Bolstad said.

"I believe this program can be expanded," he said, "but I don't know how much."

For example, when the Humane Society tried to apply PZP-22, a two-year form of the drug, to the Cedar Mountains herd in Utah, the terrain was too rough, and the horses too skittish, for the animals to be manually darted, Bolstad said.

Eventually, 70 of the estimated 124 mares were treated during a helicopter gather in 2009. In the first year, 24 percent of the treated mares birthed foals, compared with 65 percent of the untreated mares.

Still, the herd, which roams nearly 200,000 acres of white salt flats with sagebrush and cedars, grew from about 400 to 666 horses between 2009 and 2012. The 17 percent annual growth rate was "unacceptably high," according to the Humane Society, though it was substantially lower than in some previous years.

Bolstad said it costs an average of $2,500 to gather and treat each mare with PZP-22, which costs $300 a dose. Considering there are 16,000 reproducing mares on the range, it would cost well more than half of BLM's current wild horse budget to treat them all, he said.

In addition, Bolstad cautioned that some trials of PZP-22 have shown limited effectiveness in the second year.

"I acknowledge that not great amounts of money have gone to contraception," Bolstad said. "It would be tremendously advantageous to have a longer-lasting drug."

Still, BLM estimates that each time it prevents a young horse from having to be maintained in long-term holding for the remainder of its life after capture, it saves $13,000.

PZP alone will not solve the problem of herd growth, Bolstad said. The agency will also need to adjust sex ratios in herds to favor stallions, in addition to sterilizing some horses, a process that often attracts controversy.

Even as it pursues fertility control, BLM will still have to remove horses when they exceed appropriate management levels, lest it run afoul of the Wild Free-Ranging Horse and Burro Act of 1971 and the agency's mandate to balance horses with other users, such as livestock, Bolstad said.

Currently, the agency estimates there are still 14,000 more horses than Western rangelands can support.

Bureaucratic and political barriers

But in failing to use PZP more widely across the Western range, BLM has allowed perfect to be the enemy of much better, critics say.

"There is an attitude in the agency to do nothing unless a silver bullet is available," said the Science and Conservation Center's Kirkpatrick, who has been pioneering the use of PZP in wild horses, deer, and elephants since 1988.

Kirkpatrick has trained roughly 170 people—including Felix, of Friends of the Mustangs—in how to administer PZP. Currently, his class in Billings is the only place in the country where volunteers can be certified to administer the drug, he said.

"The impediments at BLM are almost all political, economic, and cultural," he said.

For example, the managers of herd areas are rewarded for the number of horses they remove, not the number of horses they stop from breeding, he said. And there's often a policy disconnect between the BLM's D.C. office and the agency's Reno, Nev., office, which is in charge of overseeing the field offices, Kirkpatrick said.

Marty Felix, a volunteer for Friends of the Mustangs, practices shooting darts on a target as Jim Dollerschell, a BLM range manager, watches. Felix estimates she has prevented more than 100 pregnancies by darting mares in the Little Book Cliffs herd. Photo by Phil Taylor.

Several years ago, BLM's D.C. office sent a memo ordering that no mares be returned from gathers without being treated with PZP. But some field offices ignored it, Kirkpatrick said, and in one case, a BLM official in Wyoming told a local TV news station that contraception doesn't work.

"When it comes to the wild horse and burro program, there is no BLM," Kirkpatrick said. "There are 10 state offices each with a politically appointed state director with lots of independence."

While some of the larger herd-management areas in the West don't lend themselves to the fertility control program employed at Assateague, Kirkpatrick said he encouraged BLM 15 years ago to begin applying PZP to every mare it gathered from the range.

If the agency had done so, each mare would have been treated five times by now, he said.

Kirkpatrick said BLM must also insist that its contractors gather every horse on the range, instead of stopping after the easiest 80 percent of horses are rounded up. Currently, the most difficult horses to catch are left on the range to reproduce, passing on those characteristics to their foals, he said.

"What they should be saying to the contractor is catch every damn horse on the range and bring them in," he said. "But the contractors essentially make the rules."

The Humane Society in a white paper delivered to BLM in May criticized the agency for dismissing PZP after early trials suggested the two-year drug failed to work in the second year.

"The BLM is increasingly claiming that PZP doesn't work," the group said. "However, the BLM seems to use the principle that gather, remove and warehouse must be the default until the alternative is perfect, not simply better than the status quo."

The one-year drug, also known as native PZP, the group added, is "the only current, proven alternative to further destabilizing the program."

But to apply PZP more widely, the agency will need more support from volunteer groups like Friends of the Mustangs, even though such partnerships are rare across much of the rest of the West, where BLM is either sued or excoriated by advocacy groups each time it orders a roundup.

"Most of the groups trying to work with BLM are antagonizing them," Friends of Mustangs' Felix said. "They're just out to get the BLM. They're not cooperating, and that's too bad."

One way BLM could garner the public's trust is by improving how it counts horses and by being more transparent about how it determines appropriate herd levels, the National Academy of Sciences report found.

"Data and methods used to inform decisions should be scientifically defensible," the report said, "and the public should be able to understand the methods used and how they are implemented and to access the data used to make decisions."

With the right political leadership, BLM could foster a better working relationship with nongovernmental organizations, Kirkpatrick said.

"Suddenly, you have these NGO groups that sit down and say, 'Let's quit fighting,'" he said. "They have one common goal: Get these horses treated."

Originally Posted By E & E Publishing