The small-billed moa-nalo (Ptaiochen pau), also known as the stumbling moa-nalo, is a species of moa-nalo, one of a group of extinct, flightless, large goose-like ducks, which evolved in the Hawaiian Islands of the North Pacific Ocean. It was described in 1991 from subfossil material collected in September 1982 by Storrs Olson, Helen James and others, from the Auwahi Cave on the southern slopes of Haleakalā, on the island of Maui.