Birds of Hulē‘ia
Hawaiian Duck / Anas wyvilliana / Koloa maoli (native duck)
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.
Koloa can be found in lowland wetlands, river valleys, and mountain streams.
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.
Saving Hawai‘i's Native Duck