“Wild Horse Remuda” by LYLE GLASS.

A remuda of wild horses trotting around as they are being herded by a young stallion who just took over from an older stallion. The older stallion was trying to get his herd back and the young stallion was keeping the herd away from him. The take over didn't last long as the next day the young stallion was by himself, so the older stallion evidently got his herd back. I witnessed most of the battle.
Tweaked in PSE7.

Photographed in Theodore Roosevelt National Park, South Unit, Medora, North Dakota on 4-21-2012 at 2:36 p.m.