Population
Estimated population is 2,200 (2010) and decreasing.
Status EN
Habitat loss through grazing, hunting, predation by introduced mammals and hydridization with Mallard (Anas platyrhynchos) are the main threats.
For more information see BirdLife International Species Factsheet.
Food
An opportunistic feeder, taking invertebrates, seeds and plant matter.
Voice
Quacking similar to that of Mallard (Anas platyrhynchos), but softer and uttered less often.
Hawaiian Duck (Anas wyvilliana) [XC235005]
by Phoenix Birder from Hanalei NWR, Kauai County, Hawaii, United States (call)
Hawaiian Duck (Anas wyvilliana) [XC234981]
by Dan Lane from Kahuku, Honolulu County, Hawaii, United States (call, song)
Subspecies
Considered by some authors to be a subspecies of Mallard (Anas platyrhynchos).
No subspecies.
Similar Species
Female Mallard (Anas platyrhynchos) which is much larger, with white rather than buff outer tail feathers and blue-purple speculum. Hybrid Mallard (Anas platyrhynchos) x Hawaiian Duck (Anas wyvilliana) can have any combination of parental characters, but usually larger than pure birds.
References
See References.