1The Grey Whale
Embarking on an epic journey for food, a mother whale leads her calf on the longest migration of any mammal.
2The Elephant Seal
A four-ton elephant seal returns to his breeding beach on the cusp of summer—and quickly learns the competition for females is fierce.
3The Giant Otter
In the Brazilian Pantanal—a wetland larger than England—a six-foot otter attempts to raise her cubs in the shadow of hungry jaguars.
4The Gorilla
Makumba is one of the best studied gorillas in the world. Now past his prime, he must find new ways to maintain his status as king of the jungle.
5The Hippo
In Earth's largest inland delta, Africa's deadliest mammal fights to keep his family afloat as the dry season approaches.
6The Brown Bear
Rocky Mountain summers are fleeting, leading local bears to gain weight, sharpen defenses, and engage in a dynamic fight for domination.
7The Ostrich
A blazing sun scorches the African savanna, where the planet's biggest bird protects his eggs and giraffes struggle to fuel their towering bodies.
8The Orangutan
In Borneo, apes and monkeys train their babies in the treetops, but with gravity against them, the stakes are high—and crocodiles lurk below.
9The Tiger
Monsoon season drives giants toward higher ground, and big cats battle it out to claim dwindling territory in an Indian valley.
10The Polar Bear
Subzero temperatures force polar bears to bulk up—but as summer returns and the planet grows warmer, they find themselves on thin ice.