This trio of ducks has me somewhat baffled. They flew in one day and were gone by the day's end.

These ducks have so many traits of the endemic Hawaiian duck or koloa maoli (Anas wyvilliana): they are all small birds; overall mottled pattern; did not quack (koloa maoli quack less or softer than mallards), among other slight traits.

But, when I see "koloa maoli" near sea level on Oʻahu, I really have my suspicions that the bird(s) may be a hybrid with a feral mallard (Anas platyrhynchos), which they frequently mate with.

Koloa maoli (Anas wyvilliana) is endemic and an endangered species in the main Hawaiian Islands; whereas the mallard is not and very common. Hybridization is a major problem with the feral mallards.

These ducks were seen in Waimea Valley, Oʻahu (Man-made Pond #3) swimming amongst introduced waterlilies, Victoria sp., and native ʻakaʻakai (Schoenoplectus tabernaemontani).