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Hawaiian duck / Koloa maoli

Anas wyvilliana

Hawaii-eend / Hawaiiente / Canard d'Hawaii


The Hawaiian duck  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 Hawaiʻi. 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 species qualifies as Endangered (IUCN, 2013) because it is inferred to have a very small and fragmented range on a few islands, where wetlands are being lost and degraded, and where hybridisation is slowly reducing the number of pure individuals.


The Hawaiian duck was once an inhabitant of all the main Hawaiian Islands except Lana'i and Kaho'olawe (U.S. Fish and Wildlife Service 2005), but is now restricted to Kaua'i and Ni'ihau, and is reintroduced on O'ahu, Big Island and Maui. Its population was estimated to number 2,525 individuals (U.S. Fish and Wildlife Service 2002c), but this has been revised to 2,200 (K. Uyehara, A. Marshall and A. Engilis Jr. in litt. 2007), with c.2,000 on Kaua'i and Ni'ihau and c.200 on Big Island (Callaghan and Green 1993, Engilis and Pratt 1993, U.S. Fish and Wildlife Service 2005, K. Uyehara, A. Marshall and A. Engilis Jr. in litt. 2007). In 1997, 5-11 were seen on Maui (F. Duvall per P. Baker in litt.1999). In addition, some of the c.300 birds on O'ahu and c.50 birds on Maui that resembleA. wyvilliana are pure birds (U.S. Fish and Wildlife Service 2005). However, most of the birds on these two islands are A. platyrhynchos × A. wyvilliana hybrids. The distribution and abundance of the species is not clear in some areas due to difficulties in the identification and distinguishing of hybrids (U.S. Fish and Wildlife Service 2005).


The species's population is estimated to number c.2,200 individuals (K. Uyehara, A. Marshall and A. Engilis Jr. in litt. 2007), roughly equivalent to 1,500 mature individuals.


It inhabits wetlands, including coastal ponds, lakes, swamps, flooded grasslands, mountain streams, anthropogenic water-bodies and occasionally boggy forests, as high as 3,300 m (Todd 1996, T. C. Telfer in litt. 1999). Breeding occurs year-round, with the majority of breeding records coming between March and June (K. Uyehara, A. Marshall and A. Engilis Jr in litt. 2007). It is an opportunistic feeder, taking invertebrates, seeds and plant matter (U.S. Fish and Wildlife Service 2005). It favours larger (over 0.23 ha) wetlands far (at least 600 m) from human housing, and is twice as likely to be found on wetlands enhanced or created specifically for the species by the USDA's Wetlands Reserve Program than on agricultural ponds (Uyehara et al. 2008, K. Uyehara in litt.2012).


On Kaua'i, the Hanalei National Wildlife Refuge is an important area for the species, especially in winter (Todd 1996). The species was reintroduced to O'ahu through the release of 326 captive-bred birds between 1958 and 1982 (U.S. Fish and Wildlife Service 2005); in 1989, fewer than 12 captive-bred birds were released on Maui; and between 1976 and 1982, the species was reestablished on the Big Island also through the release of captive-bred birds (U.S. Fish and Wildlife Service 2005). In the late 1980s, the importation of A. platyrhynchos was restricted by the state, with exceptions only for research and exhibition (Uyehara et al. 2007). In 2002, the department of agriculture placed an embargo on all birds shipped to the Hawaiian Islands, to protect the public from West Nile Virus. Research is being carried out to develop techniques for the identification of hybrids (Uyehara et al. 2007). This will require simultaneous genetic testing and morphological characterisation (U.S. Fish and Wildlife Service 2005).


More information: http://www.iucnredlist.org/details/22680199/0



Above: adult drakes Hawaiian duck



Above: adult females Hawaiian duck



Above: adult drake Hawaiian duck



Above: Hawaiian ducks, in summer plumage



Above: adult drake Hawaiian ducks



Above: a pair of Hawaiian ducks, drake at right



Above: two adult drakes of Hawaiian duck



Above: Mallard-types from America. Click to enlarge.

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