The Bureau of Land Management earlier this week completed a 20-day helicopter roundup of wild horses north of Eureka, Nev. A total of 1,139 horses were permanently removed from their home range on the Diamond Complex, while 43 were captured then released: 21 mares treated with the safe, proven fertility control vaccine, which is effective for 1-2 years, in order to slow reproduction, with 22 studs.

Twenty-six deaths were reported, the last of which took place on Tuesday, the roundup’s final day, when a 7-year-old sorrel mare suffered a broken neck when it struck a panel while horses were being sorted, according to BLM. The agency classified four deaths as “acute,” or as a result of the roundup, and 22 as being euthanized for “pre-existing / chronic” conditions.

A total of 480 studs, 493 mares, and 223 foals were captured.

An estimated 300 wild horses remain on the complex after the roundup, the stated purpose of which was to “prevent undue or unnecessary degradation of the public lands associated with excess wild horses and burros” and “protect habitat for other wildlife species such as sage grouse, pronghorn antelope, and mule deer.” The BLM also said in a press release that the roundup was necessary because of “severe drought conditions throughout Central Nevada.”

The agency-set Appropriate Management Level for the 258,000-acre Diamond Complex is 123-210 wild horses, or as low as one horse for every 2,098 acres.

BLM has allocated up to 24,348 Animal Unit Months for privately owned livestock and sheep that graze on the Diamond Complex compared to 2,520 for wild horses. One Animal Unit Month, or AUM, is the enough forage for one cow and her calf, one horse, or five sheep or goats for a month.

The Diamond Complex is made up of both public and private lands. It includes the Diamond Herd Management Area, Diamond Hills North Herd Management Area, and Diamond Hills South Herd Management Area.

Captured wild horses chosen for removal were shipped to the Palomino Valley Off-Range Corrals, Reno, Nevada, to be prepared for adoption or sale.

Click here for BLM planning documents.