A Billion-Dollar Problem? Examining Wild Horse Management Challenges

June 23, 2016

AWHC Contributor

The Bureau of Land Management (BLM) recently announced a significant challenge: managing over 40,000 wild horses in holding pens across the American West. This issue has sparked controversy among wild horse advocates, ranchers, and federal officials. A potential solution lies in the Porcine zona pellucida (PZP) vaccine, which offers a humane method of population control.

More than 40,000 wild horses, gathered from U.S. public lands, are currently sitting in holding pens across the American West. The wild horse population issue has proven controversial among wild horse advocates who claim that horses — by right of the 1971 Wild Free Roaming Horse and Burro Act — should remain on public lands, for ranchers who use public lands under Bureau of Land Management cattle grazing permits, and for federal officials who work under tight budget constraints.

One solution, some say, could lie in a birth-control vaccine, a medicine that is currently being used locally in a federally managed herd.

PZP: A Promising Solution

The Porcine zona pellucida vaccine, or PZP, as it’s commonly called, is not a new discovery. It’s been around for decades — at least 40 years, according to Ginger Kathrens, executive director of the Cloud Foundation, a wild horse advocacy nonprofit based in Colorado Springs.

PZP is an immunocontraceptive vaccine for female wildlife: in short, animal birth control. Kathrens said that wild horse advocates for decades have urged the BLM to use PZP as a way to control wild horse populations, which they argue would end the need for gathers, or round-ups, that lead to excess horses waiting for years (and sometimes a lifetime) in holding pens to be adopted.

“We’ve pleaded with them to use the tools in their toolbox,” she said. “It doesn’t matter if you have the tool if you don’t use it.”

Kathrens, like most advocates, worries about the wild horse populations dwindling, or that herds across the U.S. might be eliminated altogether because of the tight federal budget and the BLM’s claim that there are too many horses.

But she’s not exactly buying the BLM’s “billion-dollar problem.” She said she has yet to see a federal analysis of where the BLM has gotten its calculations. According to her, federal officials are taking the “sky is falling” approach, one she fears could prompt Congress to consider permanently sterilizing or even executing wild horses.

“How do you get to $1 billion?” she asked. “In short-term holding, it takes slightly more than $5 a day. Take those in holding and multiply — they live to 27 or 28 — Then you can arrive at a billion-dollar figure over two or three decades. … It’s not a problem tomorrow, but it’s cumulative.”

The BLM, Kathrens agrees, can’t keep holding the horses. But the fact the BLM won’t adopt the use of PZP agency-wide to control populations is outrageous to her.

“We have these instances where it works, in the Pryor Herd in Wyoming and in Spring Creek, but never agency-wide developed and planned with safe and proven vaccines,” she said.

The Spring Creek Basin Herd

The Spring Creek Basin Herd, a group of 35 to 65 federally managed wild horses, roams 23,000 acres in Disappointment Valley in the west end of San Miguel County. Managed by Wild Horse Specialist Mike Jensen of the Tres Rios Dolores BLM Field Office, the herd hasn’t experienced a gather or removal of excess horses since 2011. That’s because its population has been stabilized.

Jensen said the BLM has effectively used PZP there for the last five to six years, and the vaccine treatment has kept mortality and birth rates about equal. Last year, three foals were born; two were born this year.

Some advocates who are championing the mustang might ask, “If PZP is working in certain herd areas, why can’t the vaccine become standard BLM policy and the solution to the BLM’s proclaimed crisis?”

Administering the vaccine isn’t as easy as one might think. In fact, Jensen said the task would be extremely difficult for his staff to do alone.

“It’s labor-intensive, time-intensive, for three or so months during the year when we have to get those horses vaccinated,” Jensen said.

He relies on local mustang advocate groups to get the birth control mission, a detailed process, accomplished.

The mares first have to be identified and selected for the vaccination process. Then, the chosen mares have to be accessible in the territory. The dart gun Jensen uses is effective at approximately 30 yards away. Jensen said that when initially treating a mare, the vaccine must be given twice, first as a primer to allow the horse’s body to begin responding, and then again three months later to ensure its effectiveness. This means first-time mares must be located twice and darted — not always an easy task on thousands of acres.

Jensen credits the wild horse advocates who take photographs of the mares and keep records of who’s received the birth control and when. Those records are used the following year, when the BLM and advocates determine which mares should be treated, and some of them repeatedly for a few years in a row. To keep a mare from getting pregnant the following year, a mare must receive a PZP booster.

Deciding which mares to vaccinate also requires thought. Many believe it’s important that a mare be given the opportunity to produce at least one foal. In this way, her genetics make a contribution to a herd. Sometimes age plays a factor. In the Pryor Herd in Wyoming, where PZP is effectively stabilizing population growth, mares over age 20 (that have also foaled) receive PZP, and as an added bonus, those aged mares can have their life span lengthened.

Is There a Downside to PZP?

PZP is reversible. It doesn’t permanently sterilize a mare — unless, Kathrens said, it’s used five years or more consecutively.

In some circumstances, a mare that has been treated with PZP for a few years may be left untreated thereafter, and she can later conceive and then foal.

Still, some wild horse advocates urge the BLM to use caution with PZP.

Film director and wild horse advocate James Kleinert said that while vaccinating the mares in wild horse herds is better than some of the “brutal gathers” that have occurred, he worries that PZP can be overused. He cites wildlife biologist Craig Downer, author of the book “The Wild Horse Conspiracy,” in claiming that PZP is unnatural.

Kleinert said the vaccine can skew the sex ratios and establish an excess of males within a herd. He believes the drug also can damage the natural social structures of a wild horse society. The wild horses, he said, need more support to vary their genetics in herds throughout the West. He said the mustang numbers in Spring Creek Basin specifically should be assessed by a third-party and that the local environment might be able to support an increase in the horse population.

“The last time a range management assessment was done, there were over 200 cattle grazing in the wild horse herd management area from November to March,” he said. “This had big impacts on the forage.”

Jensen said he knows that some wild horse advocates don’t like the use of PZP and insist that a band of horses can self-regulate their populations. He doesn’t agree.

“What we have seen through the wild horse program is that doesn’t happen,” he said. “Horses are horses, and they’ll reproduce.”

According to him, PZP by nature is not a hormone treatment. He said the medicine does not change the mares’ physiology and that even when vaccinated, they will still have a heat cycle and “breed” with band stallions, though without conceiving. Jensen said that PZP will not interfere with a herds’ social structures.

PZP on a Larger Scale?

The BLM and local advocates agree that PZP seems to be working in San Miguel County.

Jensen said the self-named “Wild Bunch” — the Colorado Chapter of National Mustang Association, the Four Corners Backcountry Horsemen and Mesa Verde Backcountry Horsemen — all led by TJ Holmes, are what help make the PZP program in Spring Creek possible and successful.

“Without them, it would be difficult to do,” he said.

Holmes said she agreed that the unique Spring Creek Basin partnership is beneficial.

“Spring Creek Basin mustangs and advocates are fortunate to enjoy an excellent partnership with Tres Rios Field Office in Dolores, specifically with herd manager Mike Jensen,” she said. “Because of that commitment and dedication to our Spring Creek Basin mustangs and their range, we are able to set and achieve goals that benefit both.”

Jensen is not sure if PZP is possible as an agency-wide solution in stabilizing horse populations.

PZP is relatively inexpensive, he said.

Still, some herd areas in Nevada are as large as 300,000 acres. Some of those contain as many as 2,500 horses. Locating and identifying mares in those larger herd areas would likely be more challenging. Jensen said that a temporary gather — disliked by most advocates — might have to be performed as a way to find, trap and release mares to be darted with birth control.

And, would those larger herds have the advocate support, essential for Jensen, that could help play a role in the process?

Advocates Press On

Kleinert doesn’t trust the BLM. He said many advocates fear that federal officials are overestimating wild horse numbers. He urges all to get their hands on the case study “America’s Mustangs & Burros: What’s Left, The High Costs of Miscalculating and Will They Survive?” by C.R. MacDonald. The horses, he said, are in a more critical situation than they were in 1971 when the Wild Free Roaming Horse and Burro Act was established.

Kleinert recently sued the BLM. According to him, a federal judge has admonished the agency for withholding records he requested for an investigative wild horse documentary film he is making.

Kathrens said she mostly approves of herd management in places like Spring Creek Basin and in Wyoming with the Pryor Herd, though she wonders if those herd areas could support more horses. But, she worries about what the BLM might have in store as a remedy to the looming wild horse crisis.

With so many mustangs in holding and needing adoptive homes, combined with the lack of an agency-wide plan to use PZP across the board, she fears that permanent sterilization is on the horizon. To her, as well as other advocates, the suggestion of gelding (castrating) the stallions and removing the mares’ ovaries is horrific. The surgery, she said, makes wild animals less wild and changes the horses’ behavior as well as herd social dynamics.

This week, Kathrens traveled to Washington, D.C., as an invited expert to give testimony to the U.S. House of Representatives Subcommittee for the Interior, Environment and Related Agencies on the wild horse population issue. She gave a five-minute speech Tuesday afternoon on why the BLM should never consider permanent sterilization.