What is a Koloa maoli?
Koloa maoli = native duck. Also known as the Hawaiian Duck (Anas wyvilliana), it is an endangered species found only in the Hawaiian Islands.
What does it look like?
It is a petite, dark brown duck with orange feet and bills that have yellow-green tones (males) or orange-fleshy tones (female). When they spread their wings, green to blue-purple feathers are visible. The male is slightly larger than the female. The Koloa maoli is quiet and secretive. To see one requires knowing where to look and patience.
Is the Koloa maoli the only native Hawaiian duck?
No, there are two. Koloa maoli is Hawaii’s last native duck remaining in the main Hawaiian Islands. The second native duck, critically endangered, is the Laysan Duck which is isolated on Laysan Island and Midway Atoll in the Northwestern Hawaiian Islands. A diversity of giant, flightless island waterfowl once roamed the Hawaiian Islands. They were believed to occupy the role of the dominant plant eaters in wetland and upland habitats.
What kinds of habitat do Koloa maoli live in?
Koloa maoli live in habitats mauka to makai (mountains to sea). It is found mainly in freshwater wetlands, both natural and manmade such as mountain bogs, streams, plunge pools at the bases of waterfalls, stock watering ponds, flooded pastures, taro patches and coastal wetlands. In addition to aquatic habitats, Koloa maoli use grasslands and river banks near wetlands for nesting, feeding and resting.
What do Koloa eat as part of their natural diet?
Koloa maoli are dabbling ducks, which are known to be good divers but usually feed by dabbling or tipping rather than submerging. Dabblers have bills that are specially designed to remove food particles from the water. Koloa maoli eat primarily small invertebrates such as aquatic insects, snails and immature crayfish. They also eat freshwater limu and seeds of grasses, sedges and other wetland plants.
How many Koloa maoli are left and where can I see one?
Scientists estimate that there are roughly 2,200 individuals left and they are primarily found on the islands of Kaua‘i and Ni‘ihau and some parts of Hawai‘i Island.
Why are the Koloa maoli disappearing?
The main threats to Koloa maoli are habitat loss, introduced predators and hybridization with introduced or feral Mallards, which are domesticated ducks that breed in the wild. They are considered invasive species.
What does hybridization mean?
Hybridization = cross-breeding. In the case of Koloa maoli, hybridization occurs when a feral Mallard and Koloa maoli mate and produce hybrid offspring.
What does a hybrid look like?
Hybrids can look like small Mallards, a Mallard-Koloa maoli mix or large Koloa maoli. Sometimes it is obvious, sometimes not. When viewing ducks, overall size and behavior are good cues. Male hybrids are usually larger, have a lot of green on their heads and behave differently than Koloa maoli. They are bold and not secretive. For example, hybrids and feral Mallards are common in urban and park ponds, travel in large flocks and behave like domestic ducks; Koloa maoli are more common in remote wetlands and streams where there are few people, traveling alone, in pairs, or in small flocks, and they behave like wild ducks.
How you can you tell a hybrid from a pure Koloa?
Even the experts have trouble telling the difference because hybrid size and plumage varies greatly. Some of the main characteristics are weight, amount of green on the head and gray on the flanks (males) and wing measurements. Scientists are using DNA analysis to best determine a Koloa maoli from a hybrid.
Why is hybridization with feral Mallards such a problem?
Hybridization is leading to the extinction of Koloa maoli. We have already lost Koloa maoli on O‘ahu and Maui where there are few, if any, left. True Koloa maoli are believed to exist only on Kaua‘i, Ni‘ihau and parts of Hawai‘i Island.
What is being done to help and is it really possible to save them?
Yes, it is possible to save the Koloa maoli from extinction. The 3 main “help” categories are:
- Policies - There are changes being proposed to make laws that prevent the spread of invasive Mallards and protect Koloa maoli;
- Biologists and managers are working together to develop methods to identify and humanely remove invasive Mallards and hybrids; and perhaps most importantly,
- Outreach – increased efforts are being made to educate the public about the problems invasive Mallards are causing for our native waterbirds. The public is a critical part of the solution.
What can I do to help?
- Do not feed or shelter feral Mallards.
- Do not import, buy or sell Mallards or their eggs.
- Do not release Mallards into the wild. Consider having Mallards removed from your property. Contact the State DOFAW at (808) 973-9786 for a permit.
- Be a responsible owner of domestic ducks (e.g., Pekin, Rouen) by keeping ducks, penned, pinioned or clipped so that they do not leave your property.
- Keep your pets like dogs and cats away from wetland areas.
- Support legislation to protect Hawaii’s native birds.
- Help improve the habitat of Koloa maoli and other native waterbirds by removing invasive plants that are taking over wetlands. Go to malamahawaii.org/get_involved/volunteer.php to see volunteer opportunities.
Mālama Hawai‘i, December 2008
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