Wild horse population projected to reach catastrophic levels

Commissioned by the U.S. Bureau of Land Management (BLM) to study the effectiveness of efforts to manage the wild horse population on western lands, a National Research Council (NRC) committee published its report, “Using Science to Improve the BLM Wild Horse and Burro Program: A Way Forward,” in the National Academies Press this spring. The committee concluded that the program’s current practices are unsustainable.

The committee, chaired by Guy H. Palmer, DVM, PhD, director of the Paul G. Allen School for Global Health at Washington State University, says that if processes go unchanged and trends continue, the already overpopulated American West could see the number of horses double in four years and triple in six years. The longstanding practice of removing horses to long-term holding facilities to manage rangeland numbers does nothing to control the high population growth rate, the NRC committee says.

“No one really wants to see more horses in long-term holding,” Palmer says in a National Academies video. “This is not the vision of what the public wants to see with horses on these wild lands.” The number of wild horses in holding facilities now far outnumbers free-roaming horses on public lands.

The committee wants to eliminate the need for long-term holding facilities altogether. The first step? Collecting better data, Palmer says. Program directors need to understand exactly how many free-roaming horses there are so they can, one, protect the animals’ health, and two, assess the impact of population control strategies, he says.

One such strategy is to implement widespread and consistent fertility control. The committee identified three methods in particular—porcine zona pellucida (PZP) and GonaCon for mares and chemical vasectomy for stallions—as effective approaches. Robert A. Garrott of Montana State University and Madan K. Oli of the University of Florida, authors of Science magazine’s “A Critical Crossroad for BLM’s Wild Horse Program” (August 2013) estimate that the typical 15 to 20 percent annual population increase of western herds could be halved by means of contraceptive vaccines.

Garrott and Oli note that contraception would only reduce, not stabilize or reverse, population growth. Therefore they suggest that removal of horses from public lands will have to increase in the short term. “If a gather-and-removal effort reduced the western horse population to the BLM’s goal of 23,622 horses and aggressive contraception treatment was initiated, then BLM need only remove 2,000 to 3,000 horses annually to maintain its goal,” the article states.

That level of removal would more closely match adoption demand, theoretically eliminating the need for long-term holding facilities. However, under the present budget, increased removal seems unlikely. The BLM cites funding constraints and lack of additional capacity in holding facilities as reasons for substantially reducing its scheduled horse removals this year.

“If the horses just continue to grow regardless of how much rangeland is allocated to them, in the end, two things are assured to happen,” Palmer says. “The rangeland loses its quality—it’s actually destroyed for use for other wild animals—and the other problem with that is that, eventually, the horses themselves will become ill and unthrifty due to inadequate feed and inadequate access to water.”

Stakeholders met Sept. 9-11 at the Wild Horse and Burro Advisory Board meeting in Arlington, Va., to discuss the committee’s findings and possible strategies to achieve its suggestions. Garrott emphasized to those in attendance that despite necessity, the tools to actively manage the population would meet economic and political challenges. “All the active management tools you have are expensive,” Garrott said. “They’re all invasive.”

The National Wild Horse and Burro Advisory Board accepted most of the committee’s key findings, although discussion will continue over preferred methods of fertility control. Both entities agree that change is imperative. “We want to reduce the growth rate to something that can be managed so that the horses, rather than being taken off lands into long-term holding facilities, can actually be maintained on the land as a thriving genetic population—which is the goal of the program,” Palmer says.