The Kakapo parrot of New Zealand is a unique creature in several ways. Not only is it the world’s heaviest parrot, weighing up to 9 pounds (4 kilograms) but it is the world’s only only flightless parrot, as well as the only nocturnal one. The bird was once common on both of New Zealand’s main islands. However, by the early 1970’s it was thought to have been driven into extinction by such prolific human-introduced invasive predators as rats and cats, which killed the helpless young birds in their nests on the ground. Tiny populations were later found on a couple of smaller, more remote islands. Despite an intensive program of breeding and protection by the New Zealanders, currently there are fewer than 150 kakapos left in the wild—so few that almost all of them have names given to them by conservationists.