 the hawaiian duck (anas wyvilliana) is a monochromatic, non-migratory, endangered species allied with the north american mallard (a. platyrhynchos) complex. the hawaiian duck is a species of bird in the family anatidae. it is endemic to the large islands of hawaii. some authorities treat it as an island subspecies of the mallard, based on their capacity to produce fertile hybrids, but it appears well distinct and capability of hybridization is meaningless in dabbling duck taxonomy. the native hawaiian name for this duck is koloa maoli.this means "native mallard". often, it is shortened to just koloa but this term denotes the mallard if applied strictly, and all mallard-like dabbling ducks if applied loosely. this species is listed as endangered by the iucn red list of threatened species and its population trend is decreasing.birdlife international 2013. anas wyvilliana. the iucn red list of threatened species. version 2014.2. retrieved on 22 october 2014. ==physiology== ===appearance=== both male and female are mottled brown in color and resemble a female mallard. the males are usually bigger than the females. the speculum feathers of both sexes are green to blue, bordered on both sides by white. the tail is dark overall, unlike the black-and-white tail of a mallard. the feet and legs are orange to yellow-orange. the bill is olive green in the male and dull orange with dark markings in the female. the adult male has a darker head and neck, which is also sometimes green. the female is generally lighter colored than the male and has plainer back feathers. a first-year male hawaiian duck looks like an eclipse-plumaged male mallard. seasonal plumage differences, individual variation, and variation between islands can make it difficult to differentiate between hawaiian ducks, female mallards and hybrids of hawaiian ducks and mallards. in addition, the extent of hybridization at a location can contribute to the difficulty of identification.u.s. fish and wildlife service. 2011. recovery plan for hawaiian waterbirds, second revision. u.s. fish and wildlife service, portland, oregon. xx + 233 pp. ===body size=== the male hawaiian duck has an average length of 48â50&nbsp;cm (19â20&nbsp;in) and the female has an average length
Anas Animals_described_in_1878 Birds_of_Hawaii Ducks Endemic_fauna_of_Hawaii IUCN_Red_List_endangered_species