Bird Checklists of the United States

The largest endangered forest bird in Hawaii is the 'io(Hawaiian Hawk). It is frequently seen soaring high above the tree canopy in search of birds, large insects, mice and rats. The 'io occurs in two color phases. Light-phase birds are dark brown above and pale below with dark streaking. Dark-phase birds are all brown. While color does not indicate age or sex, younger birds tend to have paler heads. The female is slightly larger than the male.

The 'io population has increased during recent years. Rarely seen in the 1960's and 1970's, hawks are now frequently observed from the coast to the tree line on mountain slopes. Many Hawaiian families believe the 'io to be their guardian spirit('aumakua).