A successful, intense program in Nevada involving wild horses could help refine the science of fertility control in additional wild horse populations as well other species like elephants in Africa.
The American Wild Horse Campaign, because of its extensive data set on more than 3,000 wild horses in the Virginia Range, will be working next year with a researcher from the University of Pretoria to develop additional science around the administration of a fertility control drug called porcine zona pellucida or PZP.
“We are really excited to begin working with the university,” Suzanne Roy, the campaign’s executive director, said. “There are a number of elephant preserves that use PZP to manage elephants in limited habitats.”
In the campaign’s program, trained volunteers go out in teams, stalking wild horse bands across a range that spans 300,000 acres in the greater Reno area of Nevada.
Using an extensive database documenting each of the horses’ colors, distinctive markings, gender, family affiliations and more, a spotter pulls up a mare’s fertility control vaccine history to determine whether she needs a dose.
If so, another volunteer — usually from a distance of 25 yards — shoots the dart into the hip of the mare to prevent a pregnancy. The mares are given a “primer” and then a booster within 12 months, followed by more boosters in subsequent years.
The American Wild Horse Campaign, in an agreement the nonprofit advocacy group reached with the Nevada Department of Agriculture, has treated 1,333 mares and administered 3,075 treatments since it began this program on April 9, 2019, for a population of 3,000 horses occupying state and private land.
The vaccination effort impacting so many wild mares makes the campaign’s program the largest of its kind in the world, according to the Science and Conservation Center in Billings, Montana.
“I think this has been a success because it has been a real community-based program with support from a lot of volunteers to get those horses darted,” Roy said. “We have a really large population of horses, so we have a really large volunteer force.”
A skeptic at Nevada’s agriculture department told Roy in 2019 that the program to slow population growth among the Virginia Range horses would likely fail, yet she was not deterred, nor were her volunteers — a force that has steadily grown.