The Bureau of Land Management (BLM) has announced that it will vaccinate wild mares in the Onaqui Mountain Herd Management Area (HMA) in Utah with the contraceptive porcine zona pellucida (PZP) according to its fertility control plan.

The Wild Free-Roaming Horse and Burro Act federally protects wild horse and burro herds residing in Western states and places them in the BLM’s jurisdiction. The BLM website indicates that more than 2,500 wild horses and 100 burros reside in 22 herd management areas in Utah. Herd populations within those herd management areas range from 35 to more than 400 animals.

The agency said that an estimated 317 wild horses currently reside in the Onaqui HMA in Toole County. The appropriate management level for that HMA is between 120 and 210 horses, the agency’s website said.

On May 1, BLM Utah announced that over the next five years the agency would use a remote darting program to vaccinate mares that HMA