USFWS/Robert Shallenberger

The Hawaiian Duck or koloa, is generally mottled brown and has a green to blue speculum (the distinctive feathers on the secondary wing feathers) with white borders. Adult males tend to have a darker head and neck feathers (sometimes green). Both sexes have orange legs and feet. Females have a dull orange bill. The male koloa is 19 to 20 inches in length while the female is 16 to 17 inches. Their quack is a little softer than the mallard and koloa are not as vocal.

Habitat & Behavior:
Hawaiian ducks can be found in lowland wetlands, river valleys, and mountain streams. They are cautious ducks that travel in pairs. Koloa eat mollusks, insects, and freshwater vegetation. They can begin breeding at one year old and nest year-round, but the main breeding season is between January and May. Two to ten eggs are laid in a well concealed nest lined with down and feathers. The incubation period is 30 days. Because their nests are established on the ground, they are highly vulnerable to mongoose, pig, and dog attacks. The chicks are sometimes eaten by bullfrogs and bass.

The largest number of Hawaiian ducks can be found at the Hanalei National Wildlife Refuge and at Alakoko Pond in Huleia Valley, both on the island of Kaua`i. They can also be seen in the Kahuku, Pearl Harbor, and Waialua areas of O`ahu; and at the Mana Road pond near Waimea on the Big Island.