Parrots (Psittaciformes), also known as psittacines, are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genera, found mostly in tropical and subtropical regions. The four families are the Psittaculidae, Psittacidae, Cacatuidae (cockatoos), and Strigopidae. One-third of all parrot species are threatened by extinction, with a higher aggregate extinction risk than any other comparable bird group. Parrots have a generally pantropical distribution with several species inhabiting temperate regions as well. The greatest diversity of parrots is in South America and Australasia.