TOOELE, Utah (AP) — The sound of the helicopter propeller thundered across the horizon as it dipped down toward mustangs dotting the golden brown plain. The horses burst into a gallop at the machine's approach, their high-pitched whinnies rising into the dry air.

That helicopter roundup in the mountains of western Utah removed hundreds of free-roaming wild horses, shortly before the Biden administration announced it would sharply increase the number of mustangs removed across the region. It's an emergency step land managers say is essential to preserving the ecosystem and the horses as a megad...