It's the biggest game day of the year as bighorn sheep clash head to head in Georgetown, Colorado. Olive the oiled sea otter is on the front lines fighting climate change in the kelp forests of Monterey Bay, California. In the Sky Islands of Arizona, the tiniest birds in the world refuel on their epic migration. And a pod of dolphins hunt on land in Captain Sam's Inlet, South Carolina.

Love is in the air all over the United States of Animals. Just a few feet from Highway 1 on the California coast, it's the ultimate prizefight for elephant seals. Meanwhile, Operation Migration is winding down after a flock of whooping cranes follow their "mom" to St. Marks, Florida. And it's a real fish-out-of-water story when grunions swarm the beaches of California.

Every March, the Platte River Valley in Nebraska is home to a colossal crane choir when thousands of sandhill cranes pull of the migration express to rest and refuel. Meanwhile, in Texas, a trail boss leads a cattle drive through town. And finally, witness a purple martin super-enthusiast who owns the world's largest purple martin apartment complex – with over 1,200 rooms!