Hawaiian Duck

The Hawaiian duck, or koloa maoli, is a captivating species endemic to the Hawaiian Islands. This bird is a member of the Anatidae family and is scientifically known as Anas wyvilliana. It is closely related to the mallard but is distinguished by its monochromatic plumage and non-migratory habits. The koloa maoli is a symbol of the unique avian diversity found in Hawaii.

Identification Tips

Both sexes of the Hawaiian duck are mottled brown, resembling a female mallard. The males are typically larger and have a darker head and neck, while the females are lighter with plain back feathers. Look for the green to blue speculum feathers bordered by white on both sides, and note the dark tail, which contrasts with the black-and-white tail of a mallard. The male's bill is olive green, and the female's is dull orange with dark markings. Their feet and legs range from orange to yellow-orange.

Habitat

The koloa maoli thrives in the lush wetland grasses and streams, particularly near the Kohala volcano on the main island of Hawaiʻi. They favor low wetlands, river valleys, and mountain streams, often residing in areas that are difficult to access.

Distribution

Historically, the Hawaiian duck was found across all the main Hawaiian islands except Lānaʻi and Kaho’olawe. Today, genetically pure populations are believed to exist on Kaua'i, Ni'ihau, and the highlands of Hawai'i, with hybrid swarms on O'ahu and Maui.

Behaviour

The Hawaiian duck is known for its wariness and secretive nature, typically found in pairs rather than large flocks. They do not readily associate with other animals and are most active within their preferred wetland habitats.

Song & Calls

The koloa's quack is reminiscent of a mallard's but is softer and less frequent. This subtle call is one of the many delicate sounds that contribute to the rich tapestry of Hawaii's natural soundscape.

Breeding

Breeding primarily occurs from December to May, with some pairs nesting year-round. The female lays a clutch of two to ten eggs in a well-hidden nest, and incubation lasts about four weeks. Ducklings are precocial and can enter the water shortly after hatching, but they won't be able to fly until about nine weeks old.

Similar Species

The Hawaiian duck can be confused with female mallards and their hybrids due to their similar appearance. However, careful observation of size, plumage details, and location can aid in correct identification.

Diet and Feeding

An opportunistic feeder, the Hawaiian duck's diet includes freshwater vegetation, mollusks, insects, and other aquatic invertebrates. They are known to consume a variety of foods ranging from snails and insect larvae to grass seeds and green algae.

Conservation status

The IUCN Red List classifies the Hawaiian duck as Vulnerable, with a decreasing population trend. Hybridization with feral mallards, habitat loss, and predation are significant threats to this species. Conservation efforts include habitat protection, predator control, and measures to prevent hybridization.