 The combination of a giant bill with brightly colored plumage (yellow for "R. flaviceps", orange for "R. palmeri") gave the males a very striking appearance.Koa seeds were the preferred food for the two species, but caterpillars were taken if necessary.The two prehistoric species, "R. forfex" and "R. litotes", were denizens of more lowland tropical dry forests and shrublands on Kauai, Maui, and Oahu.