The National Park Service is moving wolves to Isle Royale in Lake Superior to replenish a small pack on the island. Wolves prey on moose, which are overgrazing the island. It doesn't hurt that they are charismatic.
The fossa, Madagascar's largest predator, is a cat-like carnivore that eats everything from insects to lemurs. Because they are rare and elusive, scientists know very little about them, including how many there are.