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Hawaiian duck

Anas wyvilliana / Koloa maoli
Koloa maoli

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. 

The koloa maoli uses natural and manmade lowland wetlands, flooded grasslands, river valleys, mountain streams, montane pools, forest swamplands, aquaculture ponds, and agricultural areas. The Refuge provides suitable habitat for foraging, loafing, pair formation, and breeding. The majority of nesting occurs from March-June with broods observed year-round. Nests are placed in dense shoreline vegetation of small ponds, streams, ditches, and reservoirs. Types of vegetation associated with the nesting sites of koloa maoli include fetched and bunch-type grasses, rhizominous ferns, and shrubs.
 

The koloa maoli is an endangered waterfowl endemic to the Hawaiian Islands. The former range of the koloa includes all the main Hawaiian Islands except Lana‘i and Kaho‘olawe. Currently, the only naturally occurring population of koloa maoli exists on Kaua‘i with repatriated populations on O‘ahu, Hawai‘i, and Maui. The current Statewide population of pure koloa is estimated at 2,200 birds; approximately 2,000 individuals occur on Kaua‘i and the remainder reside on the Island of Hawai‘i. Birds on O‘ahu and Maui are thought to be primarily koloa-mallard hybrids, with estimated counts of 300 and 50 birds, respectively. 

Although hybridization is still a threat on the islands of Kaua‘i and Hawai‘i, the koloa maoli population on these two islands appear to be stable. In addition to hybridization concerns, other hazards exist for koloa maoli. Known predators of eggs and ducklings include mongooses, cattle egrets, cats, dogs; and possibly rats and Samoan crabs. ‘Auku‘u and bullfrogs have been observed to take ducklings. Avian diseases are another threat to koloa maoli with outbreaks of avian botulism occurring annually throughout the State.  

Facts About Hawaiian duck

Diet
Aquatic invertebrates, aquatic plants, seeds, grains, green algae, aquatic mollusks, crustaceans, and tadpoles

Habitat
Natural and manmade lowland wetlands, flooded grasslands, river valleys, mountain streams, montane pools, forest swamplands, aquaculture ponds, and agricultural areas

Page Photo Credits — Brenda Zaun/USFWS
Last Updated: Sep 03, 2013
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