Hawaiian Duck
Anas wyvilliana
A medium-sized duck, similar to female Mallard in appearance, but smaller and darker. Males lack the green head and curled black tail feathers of male Mallards. Both sexes have spotted tail feathers. The bill is dark greenish, with an orange tip in some females. Pure Hawaiian Ducks occur only on Kauai and montane streams and ponds on Hawaii Island. Most or all individuals on other islands are Mallard-Hawaiian Duck hybrids. Occurs in ponds, marshes, taro fields, and streams.
Taxonomy
- Scientific name
- Anas wyvilliana
- Authority
- Sclater, PL, 1878
- Order
- Anseriformes
- Family
- Anatidae
- Genus
- Anas
Range and habitat
- Migration
- Resident species
Behavior
The Hawaiian duck is a very wary bird, often found in pairs instead of large groups. The koloa is most prominently found residing in the tall, wetland grasses and streams near the Kohala volcano on the main island of Hawaiʻi. They are very secretive birds and do not associate with other animals.
Conservation
Wildlife refuges including Hanalei National Wildlife Refuge on Kaua'i are essential breeding areas for Hawaiian ducks. The species was reintroduced to O’ahu between 1958 and 1982. In 1989, twelve of these captured birds were released on the island of Maui. The species was also reestablished on the island of Hawai'i between 1976 and 1982 (U.S. Fish and Wildlife Service 2005). Throughout the 1980s, the importation of mallards to Hawai'i was limited in an effort to reduce hybridization with Hawaiian ducks. Other conservation efforts for the Hawaiian duck include the development of "techniques for the identification of hybrids", which in turn will result in "simultaneous genetic testing and morphological characterisation".<p>Hybridization is arguably one of the most serious but overlooked threats to the Hawaiian duck, specifically interbreeding between Hawaiian ducks and feral mallards. Since hybridization has been happening for an extended period of time, it is unlikely there are any pure individuals of the species left. "Determination of the population status of Hawaiian ducks and whether there are any pure Hawaiian ducks left on O`ahu will require simultaneous genetic testing and morphological characterization to develop reliable morphological criteria for distinguishing Hawaiian ducks, female mallards, and hybrids. Once such criteria are available they can be used to identify birds for removal in order to reduce interbreeding and introgression."<p>It has been shown that offspring between mallards and the Hawaiian duck produce fertile offspring. It has also been shown on Kauai that breeding Hawaiian duck/mallard crosses with Hawaiian ducks over time reduces the expression of the mallard genes showing promise to restoring the natural population. Efforts are underway to remove mallards from the islands in order to preserve the genetic diversity of the Hawaiian duck.
- Population trend
- rising
Photos
Distribution
Bird Calls
Other Birds
Yellow-chinned Spinetail
Certhiaxis cinnamomeus
Small, long-tailed spinetial that is rufous above and white below with a white eyebrow. Note the yellow chin, which can sometimes be difficult to see. Usually seen in pairs foraging in marshes, at the edges of mangroves and in damp grasslands. The song, usually given as a duet, is a loud rattle.
Yellow-capped Pygmy-Parrot
Micropsitta keiensis
A tiny parrot of lowland and foothill forest canopy in the south and west of New Guinea. Mostly green with yellow under the tail and a yellowish crown. NW birds have a red streak on the belly. Crawls actively on trunks, even upside down, like a nuthatch. May overlap with Red-breasted and Buff-faced but Yellow-capped lacks the blue crown and buff face. Call, a shrill, descending screech “kiiiiiii!”.
Gray Apalis
Apalis cinerea
Plain apalis with gray upperparts and pale underparts. The color of the underparts varies geographically, from white to more dingy gray or buff. Found in middle and high-elevation forest, most often in the canopy. Usually in pairs or small groups which will join mixed-species flocks. The main vocalization is a rough, repeated “chree,” which can be accompanied by a rattling call. Very similar to Kungwe Apalis, but separated by the darker head which shows brown tones. Also similar to male Buff-throated Apalis, but has paler upperparts.
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