The Sierra Nevada mountain range dominates California’s border with Nevada. Here the eastern flanks of the mountains give way to wide open stretches of grassland. Each spring hundreds of mustangs gather on these plains, descendants of horses brought by European explorers hundreds of years ago. Females and their foals band together in harems led by a dominant stallion. He’ll protect them and, in return, claim the right to mate with his herd. But he can never let down his guard. A roaming gang of