Wild Fortresses

S1 E3: In New Zealand, there are two wild fortresses that protect the most vulnerable native animals of this island nation. One is the remote Little Barrier Island, an ancient volcanic cone guarded by a moat of saltwater. The other is Orokonui Ecosanctuary, a hilltop citadel that's barricaded from the outside world. Here, rare birds like the hihi and kokako, and ancient reptiles like the tuatara are rebounding from the brink of extinction, safe to live out their lives in some of the most intact prehistoric ecosystems in the world.