The Kakapo (Māori: kākāpō, meaning night parrot), Strigops habroptilus (from the Greek strix, genitive strigos: owl an opsis: face; and habros: soft, and ptilon: feather), also called owl parrot, is a species of nocturnal parrot with finely blotched yellow-green plumage endemic to New Zealand. It has a distinct facial disc of sensory, vibrissa-like feathers, a large grey beak, short legs, large feet, and wings and a tail of relatively short length. A certain combination of traits makes it unique among its kind—it is the world's only flightless parrot, the heaviest parrot, nocturnal, herbivorous, it sports visible sexual dimorphism in body size, has a low basal metabolic rate, no male parental care, and is the only parrot to have a polygynous lek breeding system. It is also possibly one of the world's longest-living birds. Its anatomy typifies the tendency of bird evolution on oceanic islands with few predators and abundant food: accretion of thermodynamic efficiency at the expense of flight abilities, reduced wing muscles, a diminished keel on the sternum, a generally robust physique.