The Hawaiian Duck (Anas wyvilliana) or the Koloa is an endangered species that is endemic to Hawaii. It once flourished in Kaelepulu Pond and all the major islands of Hawaii, but is now only found in the wild on the island of Kauai. The coloring of the Koloa is very similar to the feral Mallard Duck. Coincidentally, the Koloa's quack is also very similar to the mallards'.

The Hawaiian Duck feeds on a variety of plants such as green algae, rice, and grass. It also eats earthworms, dragonflies, and snails. The rare Koloa is being driven to extinction because of hunting, draining, and altering of wetlands, wild cats and dogs, rats, mongoose, and interbreeding with feral mallards.