The Black Mambas are wardens at the Balule Nature Reserve in South Africa. What sets them apart from most of their fellow wardens throughout Africa is that they are all female. They are also unarmed. And they are highly successful at deterring poachers. The unlikely notion of the Mambas, scoffed at by some mainstream conservationists, has led to a multiplicity of benefits — some of which not even their supporters could have predicted.