 Their plumage was generally striking glossy black; some species had yellowish axillary tufts and other black outer feathers.Most of these species became extinct by habitat loss and by extensive hunting because their plumage was used for the creation of precious "aahu alii" (robes) and "ahu ula" (capes) for "alii" (Hawaiian nobility).The Kauai ōō was the last species of this genus to become extinct, probably a victim of avian malaria.