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Birds of Hulē‘ia

Hawaiian Duck / Anas wyvilliana  / Koloa maoli (native duck)

Description The 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.

Hawaiian duck - Photo credit © Hob Osterlund

Population

The koloa is endemic and used to be found on all the main Hawaiian islands except Lana‘i and Kaho‘olawe. People first noticed them to be rare around 1915. The least hybridized population today is found on the island of Kaua‘i. A koloa restoration program was initiated in 1962 by the World Wildlife Fund and the state through the Federal Aid to Wildlife Restoration Act. By 1979, 350 koloa had been released on O`ahu and Hawai‘i as part of this program.

The primary cause for the historical decline in numbers is loss of wetland habitat and hunting. Other factors include predation by introduced animals (e.g., rats, dogs, cats), hybridization (mating with other duck species), invasion of wetlands by alien plants, disease, and sometimes environmental contamination.

Habitat

Koloa can be found in lowland wetlands, river valleys, and mountain streams.

Feeding Habits

Koloa eat mollusks, insects, and freshwater vegetation.

Breeding

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.

Saving Hawai‘i's Native Duck
Hawai‘i Conservation Alliance has released a position paper about the threat that feral mallards pose to Koloa maoli, Hawai‘i’s native duck. To download the paper and find out more about what can be done to help recover koloa, please visit their website.

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