Birds of a feather flock together. And therein lies the problem for the koloa maoli, Anas wyvilliana. This endemic duck is endangered due to several factors, one of which is hybridization with feral mallards. Basically, the genes of the mallard are infiltrating the genes of the Hawaiian duck, causing "genetic extinction." To complicate the situation further, the hybrids are tough to distinguish from the real deal, making it hard to determine true population sizes and ranges. There is believed to be about 2,200 koloa maoli, with the majority on Kaua'i. Once abundant on all the major islands with the exception of Lana'i, by 1960's they were extirpated from all but Kaua'i. Captive breeding and release programs have brought them back to many islands, though those on Oahu are most likely hybrids. Both the male and female koloa maoli are mottled brown, and look a lot like female mallards. Males are a bit larger and a bit darker than the females, and have a greenish bill; females tend to be lighter in color, particularly on the head, and their bill color is more on the orangish side. They are denizens of wetlands, where they dabble the day away in search of aquatic invertebrates, molluscs, algae, small fish, and the like. Nesting occurs in dense vegetation (making them vulnerable to predation from mongooses, feral cats, and rats), primarily during the spring. Two to ten eggs are laid, and if we are lucky ducks, we'll have another clutch of Hawaiian ducks to grace our skies and waters.
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October 2014
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