The Hawaiian duck, known as the koloa maoli, is a species of bird in the family Anatidae that is endemic to the large islands of Hawai’i. It is closely related to the non-native Mallard, but the Hawaiian duck is monochromatic. Both males and females look similar, with the male slightly larger than the female.
Hawaiian ducks are also non-migratory, which means they do not travel to different locations at different times of the year.
The IUCN Red List of Threatened Species lists the Hawaiian duck as endangered.
It is said that the Hawaiian duck served as a guide for Imaikalini, a fierce blind warrior king, in Hawaiian folklore and legends.
Hawaiian Duck Description
The adult male Hawaiian duck is a striking bird with mottled brown feathers and orange legs. The head and neck are greenish-black, the speculum feathers are blue, and the chestnut-brown breast is finely spotted with dark spots. The rump and undertail-coverts are blackish, while the tail is dark grey with lighter outer rectrices and slightly upcurved central rectrices.
The coverts on the wings are grayish-brown, whereas the great coverts have white tips. The secondaries are green with a black subterminal band and a white tip, forming a conspicuous speculum in flight.
With dark flight feathers, the underwing is a grayish-white color. The eyes are brown and are surrounded by a thin, pale eyering. The legs and feet with webbed soles are yellow-orange.
On their first year, the male Hawaiian duck look like an eclipse-plumaged male mallard.
The female Hawaiian duck is smaller and has plainer back feathers than its male counterpart. She has spotted brown plumage with dark eyeliner, and her breasts are colored reddish-brown. The subterminal portion of her dark, orange-tinged bill is curved downwards.
Additionally, these Hawaiian waterbirds have light orange legs and webbed feet that allow them to paddle through the water. The deep brown color of this beautiful bird’s eyes gives her an alert and watchful appearance. Her head is proportionally larger than other ducks, making her quite distinctive among her species.
Non-breeding males have similar plumage to adult females except for the bills. Juvenile Hawaiian ducks are generally lighter colored and duller than adult females.
Listen to Hawaiian Duck
Hawaiian Duck Habitat & Range
The Hawaiian duck is native to the islands of Hawai’i and is found in both wet and dry habitats. These ducks inhabit lowland wetlands and upland forests, river valleys, pastures, wetland grasses, swamps, estuaries, suitable ponds, streams, marshes and lakes.
Hawaiian ducks are also known to range over open ocean waters near the islands, but they rarely venture more than a few miles from land.
Hawaiian ducks are non-migratory, meaning that once a pair is established on a particular island, they will remain there for most of their lives. They only travel to different locations at different times of the year. They occur year-round at Hanalei National Wildlife Refuge.
Currently, pure Hawaiian ducks live on the islands of Kauai and Niihau. It was recently reintroduced to Oahu, Big Island, and Maui islands. Ducks on other islands are most likely Mallard-Hawaiian duck hybrids. Previously, Hawaiian ducks inhabited the main Hawaiian Islands except Lanai.
Hawaiian Duck Diet & Food Habits
The Hawaiian duck is omnivorous and feeds on aquatic and terrestrial food. They forage in shallow waters, along shorelines, or on the ground. While aquatic vegetation makes up most of their diet, they consume snails, insects, insect larvae, mosquito fish, green algae, mosquito larvae, crustaceans, mollusks, grass seeds, plant matter and other aquatic invertebrates.
Hawaiian Duck Behavior
Hawaiian ducks are highly social and often gather in small groups on the ground or in shallow waters. They are generally active during the day and at night but may be less active when temperatures are hot.
Hawaiian ducks are also known to be vocal. They will communicate through a series of honking and quacking sounds.
Hawaiian ducks are very secretive birds, and they don’t associate with Hawaii’s native waterbirds and other animals.
Hawaiian Duck Nesting & Mating Habits
Some pairs nest year-round but the peak of the breeding season is between December and May. During the primary breeding season, some couples engage in spectacular nuptial flights.
The female will lay a clutch of about two to ten eggs in a shallow scrape or depression lined with down and breast feathers and plant materials such as grass, leaves and other freshwater vegetation.
The male will guard the nest as the female incubates the eggs for about 28 to 30 days. Once hatched, both parents will care for the ducklings until they are fully grown and able to fly.
Hawaiian Duck Population & Conservation Status
Due to its limited range, natural habitat loss, previous hunting pressure, predation, introduced fish and diseases, the Hawaiian duck is currently listed as Endangered by the IUCN and the U.S Fish and Wildlife Service (draft revised recovery plan).
The species is also threatened by introduced predators such as feral cats, small Asian mongooses, dogs, and rats. Additionally, the Hawaiian duck is vulnerable to avian diseases such as cholera, botulism and avian influenza.
Hybridization with feral Mallards that escaped from commercial farms remains a threat to this now-endangered species. Hybridization is when two difference species breed and produce fertile offspring. Interestingly, female Hawaiian ducks have a bizarre attraction to male mallards.
Moreover, local agriculture plays a role in the declining population of the Hawaiian ducks.
Conservation efforts are underway to protect this duck from further decline in both the wild and captivity. This includes reintroducing and protecting their wetland habitats, managing predators, monitoring populations, removing feral mallards, and captive breeding programs.
Even though population trends upwards in recent years, the long-term conservation of this beautiful water birds will depend on effective management and protection of their habitats and other measures to reduce threats. The Hawaiian duck is an iconic symbol of Hawai’i and a vital part of its unique ecosystems. It is essential to preserve and protect for generations to come.
Hawaiian Duck Hunting
Waterfowl hunting is currently prohibited on all Hawaiian Islands.
- The Hawaiian duck’s population has been affected by habitat loss, human disturbance, spread of avian diseases, introduction of non-native invasive plants, hybridization with mallards and predation threats.
- The Hawaiian duck is a medium-sized duck with blue speculum that share similar appearance with the female Mallard.
- Olive green bill in the male and dull orange with dark markings in the female.
- Adult males have darker head and neck feathers than females.
- Females lay eggs in a well-concealed nest lined with down and other soft plant materials.