Hawaiian Duck

A pair of Hawaiian ducks ( Anas wyvilliana )

The Hawaiian duck ( Anas wyvilliana ) is a species of bird in the family Anatidae ( Anatidae ). It is endemic spread to Hawaii, where it is called Koloa Maoli. The species is critically endangered, the population is estimated at 2200-2500 individuals.

Features

That relatively small breeds of ducks is pinnate mostly dark brown and reaches a length of 44-51 centimeters. The beak of the male is olive green with dark drawings on the upper mandible. The wings are mostly paler than the rest of the body, the wing mirrors are emerald green to violet-blue. A darker morphs of the males and all the females show a speckled brown plumage, with a slight reddish tint on the breast and a dark bill with dark yellow to orange -colored drawings. A lighter morphs of the males has a green drawing the head and neck and reddish markings on the chest.

Distribution and habitat

Originally located on all Hawaiian islands of Lanai and Kahoolawe except, there is today an autochthonous occurrence only on Kauai. It covers 80 percent of the total stock. The populations on the other islands resulting from reintroductions from hatcheries and are usually very small. Between 1975 and 1982, 200 individuals were located on the main island of Hawaii. Small populations are also located on Oahu, where 1958-1982 326 birds were reintroduced and Maui, where in 1989 twelve copies were released.

The Hawaiian duck lives in the wetlands of the Hawaiian Islands from sea level to 3000 m.

Way of life

The Hawaiian duck search for their food in shallow, swampy waters that are deeper than 13 cm. As habitat served her well as the taro fields, whose number is greatly decreased due to the decreased production of taro also mentioned food plant. The ducks are omnivorous and feed on snails, dragonfly larvae, worms, grass seeds, algae and water plants.

The Hawaiian duck is building their nests on the ground near the water. The female lays eight to ten eggs. Hatched throughout the year, increased breeding activity shows the duck but from January to May The exact period of incubation to hatching of the chicks in nature is not sufficiently investigated, but is less than 30 days.

The clutch and the chicks are at risk from introduced and imported robbery and rodents such as dogs, cats, mongooses and rats.

Endangering

Over the past 110 years, about a third of the wetlands have been drained in the coasts. The flood changed the hydrology of the breeding areas of the Hawaiian duck. Introduced plants such as Batis, water hyacinths and red mangroves reduced the open water and riparian areas in addition. The Hawaiian Duck was hunted on a large scale, so that in 1949 only 520 individuals were counted.

Once protected areas have been created, the biggest threat to the conservation of the species currently assumes the hybridization with the introduced mainly by North American continent mallards. Since the late 19th century and especially in the 1950s and 1960s hundreds of mallards have been reported including various cultured breeds introduced to expose them for hunting or keeping them as pets. Many of these wild ducks and mingled with the native Hawaiian ducks. As with most ducks, the hybrids are capable of reproduction and it comes at different crossing and backcrossing. On the island of Oahu is the most ducks are now hybrids. End of the 80s were enacted restrictions on imports of mallards. Only in 2002 there was a total ban on the import of birds to Hawaii. This was not primarily the protection of species, but the danger of the introduction of the West Nile virus that can be transmitted from birds to humans.