The Best Episodes Directed By Bill Markham

Majestic, powerful and dead, big cats were once thought to be solitary creatures. But we're now realizing just how collaborative they can be.

It's not all about the pouches. These mammalian misfits are full of surprises, from flamboyant kangaroo showdowns to rattling koala mating calls.

Smart, sensitive and family-oriented, our wild ape relatives rely on each other to learn - and redefine - the secrets of survival.

To rule some of the planet's most hostile lands, bears can't lean solely on brute force: it takes both brains and brawn to reach the top.