HAWAIIAN DUCK (Anas wyvilliana) – Koloa – (See images below)
DESCRIPTION: The Hawaiian Duck is a medium sized duck about 20 inches (50 cm) long, and is mostly mottled medium brown. The speculum feathers are blue with a white border and the tail is dark brown. Sexes are similar. The male has a dark green bill, whereas for the female the bill is orange with dark spots. The legs and feet are orange.
VOICE: https://www.xeno-canto.org/species/Anas-wyvilliana
NAME: Animals that are endemic to Hawaii are called ‘Hawaiian…’. The name ‘Duck’ means ‘diver’. As for the Latin genus name ‘Anas’, it means ‘duck’ again. The species name ‘wyvilliana’ was given by English zoologist Philip Sclater.
HABITAT: As a dabbling duck, this species can be found in shallow wetlands.
DIET: Vegetation and invertebrates.
NESTING: The nest is built on the ground near water in a camouflaged area. The number of eggs laid varies from 2 to 10.
DISTRIBUTION: This duck is endemic to the large Hawaiian Islands.
CONSERVATION: The Hawaiian duck is rare and endangered. Causes include inter-breeding with the related Mallard, loss of habitat and predation on eggs and ducklings by introduced feral animals such as the Javan mongoose.
NOTES: The Hawaiian duck can easily breed with the introduced Mallard, to which it is related. This makes it very difficult to be sure of the identity of the observed birds, unless DNA analysis is done. For this reason the birds shown below display both names.
SIMILAR SPECIES: Mallard, Laysan Duck
Fact sheet from the Hawaii Department of Land and Natural Resources: Hawaiian Duck – Hawaii DLNR – Oct. 2005
Fact sheet from USGS: USGS-Koloa-Factsheet – 2007

Hawaiian duck-mallard family, near Foster Community Garden, Oahu - © Denise Motard
Hawaiian duck-mallard family, Oahu
Resting Hawaiian ducks-mallards, Hamakua Marsh, Kailua, Oahu - © Denise Motard
Resting Hawaiian ducks-mallards, Kailua
Hawaiian duck-mallard hen with ducklings - Ala Moana Park, Oahu, © Denise Motard
Hawaiian duck-mallard hen with ducklings
Hawaiian duck-mallard male, Ala Moana Park, Oahu - © Denise Motard
Hawaiian duck-mallard male, Oahu
Hawaiian duck-mallard ducklings with hen, Ala Moana Park, Oahu - © Denise Motard
Hawaiian duck-mallard ducklings
Hawaiian ducks-mallards, Hamakua Marsh parking lot, Kailua, Oahu - © Denise Motard
Hawaiian ducks-mallards, Kailua, Oahu
Hawaiian duck-mallars females, Ala Moana Park, Oahu - © Denise Motard
Hawaiian duck-mallars females, Oahu
True Hawaiian duck pair, USDA Conservation Service
True Hawaiian duck pair

Most birds observed on the main Hawaiian islands are hybrids between the Hawaiian duck and the mallard to varying degrees:

It seems like this Hawaiian duck-mallard pair is pulling on the same root:

These two female hybrids look slightly different. Their DNA analysis would also probably show different results between the two: