By Pat Raia, The Horse
June 7, 2016
More than 30 wild horse advocacy groups are asking the Bureau of Land Management (BLM) to reduce the number of wild horse gathers and increase the use of the contraceptive vaccine porcine zona pellucida (PZP) to manage herd population growth.
The groups' petition comes nearly one month after the BLM announced that thecost of caring for thousands of horses residing in long-term holding facilities is largely responsible for a more than $1 billion revenue shortfall.
On June 1, 34 wild horse advocacy groups—including the American While Horse Preservation Campaign (AWHPC), the Corolla Wild Horse Fund, Habitat for Horses, and the Salt River Wild Horse Management Group—called on the BLM to increase its use of PZP in wild herds. The groups maintain the expansion will reduce the need for horse gathers to maintain horses in holding facilities.
“America does not have a wild horse overpopulation problem, we have a mismanagement problem,” opined Suzanne Roy, executive director of the AWHPC. “The PZP fertility control vaccine (could help to) humanely manage wild horse populations in the west and beyond, and the BLM needs to step up the use of this available tool.”
Tom Gorey, BLM senior public affairs specialist, said the goal of the BLM’s Wild Horse and Burro Program is to ensure the health, safety, and welfare of animal on public rangelands, and that the agency is committed to applying PZP to the maximum extent feasible. However, because most of the agency's 177 herd management areas (HMAs) are so expansive, darting animals in the wild with PZP would be logistically difficult.
“Wild horses are generally wary and unapproachable,” Gorey said. “So the animals would have to be captured, treated, and released.”
Bait trapping is a viable option in some areas where water is limited, he said, “but in most HMAs, the horses move from one watering hole to the next over an expansive area, avoiding the traps and, thus, necessitating helicopter-assisted gathers for large-scale treatments.”
There are also budgetary limitations on expanding PZP use, he said.
“The cost of rounding up and treating horses with PZP would be roughly $55 million each year,” Gorey said. “These costs would be on top of the roughly $80 million already being spent to support wild horses and burro management.” Meanwhile, not all wild horse advocates agree that PZP is the answer to wild horse overpopulation. For instance, Karen Sussman, president of the International Society for the Protection of Mustangs and Burros, said a 16-year study of four wild horse herds her group conducted showed that when wild horse social structures are not disturbed herd growth is as low as 7% under the best feed conditions.
“We expect that if the same application were used on public lands that growth would drop to between 4% and 6% because wild horses cannot be always assured of feed in terrible winter months,” Sussman said.
She also believes expanding PZP use will have in unintended consequences for wild herds: “The use of PZP will push these wild species toward lower genetic viability and eventual extinction since permanent sterility results in little as four years of application.”
While the debate continues, Gorey said the BLM is “open to new public-private partnerships that would expand the use of this vaccine.