When Charles Darwin came to the Galapagos Islands, he was stunned by the fascinating wildlife, including iguanas, tropical penguins, tortoises, and sea lions. But the native species of this World Heritage site are threatened by non-native pigs and goats that destroy egg-laden nests and devour native vegetation.

On several islands, conservationists have engaged in an all-out war against the invaders. On Santiago Island, researchers first wiped out the pigs, then turned their attention to the 80,000 goats on the island. By 2004 scientists reckon they had killed 90 percent of the goats by corralling them and killing them humanely. To get the wily hold-outs, researchers had "Judas" goats with radio collars lead them to some elusive herds. "Mata Hari" female goats, which were sterilized but gave off the scent of goats in heat, lured out the final wary males.

Status: Mission Accomplished