The Hawaiian Hawk or ‘Io (Buteo solitarius) is a buzzard native to Hawaii. It is the only hawk that occurs in Hawaii and is known to only breed on the Big Island. The species is protected as endangered in the United States however the IUCN classifies the species as near threatened.
The Hawaiian Hawk measures 16-18 inches in length and females are larger than the males. Two color phases exist: a dark phase (dark brown head, breast, and underwings), and a light color phase (dark head, light breast and light underwings). Feet and legs are yellowish in adults and greenish in juveniles.
This hawk is mostly solitary and remains in and defends its territories year round. They nest from March through September, and usually lay only one egg. The female does most of the sitting during the 38 days of incubation, while the male does the majority of the hunting. Once the egg hatches, the female will only permit the male to visit when delivering food to the nest. The chick fledges at seven or eight weeks. Fifty to seventy percent of the nests successfully fledge young.
This bird usually hunts from a stationary position, but can also dive on prey from the air. Favorite prey includes rodents, insects, small birds, and some game birds. They are opportunistic predators and are resourceful in their feeding habits. They have a shrill and high-pitched call much like their Hawaiian name: “eeeh-oh.” They are known to be very noisy during the breading season.