When Mark and Delia Owens moved to the Northern Luangwa Valley in Zambia, ivory poachers were killing savanna elephants by the hundreds. And so they stayed to fight the destruction of Africa’s wildlife, and helped stop poaching by helping villagers find alternatives in agriculture and education. Their new book is Secrets in the Savanna: Twenty-three years in the African Wilderness Unraveling the Mysteries of Elephants and People.