The Kauai akialoa is a large (17 to 19 centimeters [6.7 to 7.5 inches] total length), shorttailed Hawaiian honeycreeper with a very long, thin, decurved bill, the longest bill of any historically known Hawaiian passerine. The plumage of both sexes is olive-green; males are more brightly colored, slightly larger, and have a somewhat longer bill (USFWS 2006).