Naturalist: For decades we have known that the tuatara, a New Zealand reptile, have been approaching extinction on the South Island  But since South Island tuatara were thought to be of the same species as North Island tuatara there was no need to protect them  But new research indicates that the South Island tuatara are a distinct species, found only in that location
Because it is now known that if the South Island tuatara are lost an entire species will thereby be lost, human beings are now obliged to prevent their extinction, even if it means killing many of their unendangered natural predators
The threat of local extinction imposes no obligation to try to prevent that extinction, whereas the threat of global extinction does impose such an obligation.