LAS VEGAS (KLAS) — The Roberts Mountain Complex covers more than a half-million acres northwest of Eureka, Nevada. It’s home to at least 1,161 wild horses — a count taken in March that doesn’t even include foals born this year.

On Oct. 22, the Bureau of Land Management will begin a roundup that is expected to remove about 1,068 of the horses, according to a Monday news release. BLM says the complex — a combination of public and private land — is only rated to support 110 to 184 wild horses.

Getting down to that level will “prevent undue or unnecessary degradation of the public lands associated with excess wild horses and burros,” restoring “a thriving natural ecological balance and multiple-use relationship on public lands,” the BLM said.

The BLM is currently involved in another roundup north of Great Basin National Park that was scheduled to begin this week. About 400 horses are expected to be taken off the range in that roundup.

Helicopters are being used in both roundups, despite efforts by U.S. Rep. Dina Titus (D-Nev.) and wild horse advocates who want the BLM to end the practice.

As part of the Roberts Mountain Complex roundup, 19 mares will be treated with a fertility control vaccine called GonaCon Equine. They will be released back onto the range with 19 stallions.

Officials say 60% of the herd has moved into areas where they’re not supposed to be. “The gather is needed to halt degradation by an overpopulation of wild horses both inside and outside of the HMA, protect habitat and prevent decline of animal health,” BLM said.

The roundup is scheduled to last 19 days, and public observation is allowed. For more details on this roundup and how you can observe, go to BLM’s website.

A previous BLM roundup in the sprawling Antelope Complex produced a lawsuit earlier this year by wild horse advocacy group Wild Horse Education. The lawsuit asked the court to grant a temporary restraining order to stop the roundup, which ended with 3,078 horses gathered and 39 deaths — including 11 sudden/acute deaths from injuries that happened during the roundup. The temporary restraining order was denied, but the lawsuit brought more attention to the BLM’s use of a helicopter to pursue a horse that had a broken leg. The BLM criticized “sensational allegations” in the lawsuit. The lawsuit, which is ongoing, asserts that BLM’s internal welfare program does not comply with the law.