Witness animals struggling with their own kind over the choicest real estate. Learn to fight dirty with a guanaco, head-butt a fellow iguana to claim a piece of prime territory, and meet a hermit crab who forcibly evicts a tenant from its shell.

Bighorn rams rattle the mountaintops; Brown bears battle, desperate to fatten up for winter; Sharp-tailed grouse shake their tail-feathers; Wild stallions rumble with beauty and grace.