Campbell duck

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Campbell duck
Campbell ducks, two females on the left, two males on the right

Campbell ducks, two females on the left, two males on the right

Systematics
Order : Goose birds (Anseriformes)
Family : Duck birds (Anatidae)
Subfamily : Anatinae
Tribe : Swimming ducks (anatini)
Genre : Actual ducks ( Anas )
Type : Campbell duck
Scientific name
Anas nesiotis
( JH Fleming , 1935)
Map showing the southern tip of New Zealand, the Auckland Islands and the Campbell Islands, among others
Dent Island, the last refuge of the Campbell Duck
Typical vegetation on Campbell Island
Climate diagram of the Campbell Islands

The Campbell Duck ( Anas nesiotis ) is a flightless duck bird that is classified as a swimming duck . The species has long been considered a subspecies of the equally flightless Auckland duck and is sometimes still referred to as Campbell's Auckland duck in older literature . The duck was thought to be extinct and was not rediscovered until 1975 on Dent Island . It is still one of the rarest ducks in the world. The IUCN classifies the Campbell Duck as critically endangered .

A domestic duck breed bred in England , which is a cross between running ducks and other domestic ducks, is also known as Campbell ducks.

Appearance

The Campbell is a small, dark brown duck. Their short wings are striking. Compared to the two closely related species, the New Zealand duck and the Auckland duck, it is the smallest and darkest.

Campbell ducks show a sexual dimorphism . The males resemble the males of the Auckland duck in their splendid dress , but are darker and smaller. The head and neck are dark sepia in color and have a striking greenish shimmer. The body plumage is also dark sepia colored with a green shimmer on the back. The chest is dark chestnut colored. The underside of the body is a little lighter. In contrast to the Auckland duck, the white under-tail blanket is a little more noticeable. The beak, legs and feet are steel gray. The eyes are dark brown and surrounded by a striking white eye ring. When resting, they resemble the females, as they then largely lack the greenish shimmer of plumage. The feathers on the shoulders and the flanks are then a little less dashed. The white spot on the tail feathers is less noticeable.

The females are dark brown. The underside of the body is also lighter in them. The eye ring is also noticeably light in them. Young ducks are very similar to the females. However, they are a bit darker overall.

distribution

The Campbell Duck is a species of duck endemic to Campbell Island and the surrounding islets. They are sub-Antarctic islands belonging to New Zealand in the southern Pacific Ocean and are counted among the New Zealand Offshore Islands . The islands include Campbell Island and by far the smaller islets such as Dent Island , Jacquemart Island , Folly Island and a number of small rocky islands.

It is assumed that the Campbell Duck originally colonized all islands in this group. However, there is no evidence of this. The Campbell duck died out on the main island after seal hunters had settled on the island in 1810 and accidentally introduced rats with them. The holotype dates from 1886. However, it was not described as an independent species for the first time until 1935. The ducks were considered extinct after 1944 until they were accidentally rediscovered on Dent Island in 1975. The population on Dent Island was very low towards the end of the 20th century. Sixty to one hundred individuals lived on Dent Island. Only 25 pairs brooded on this 23-acre island, three kilometers west of the Campbell Island coastline. They survived on this island alone for a period of at least 150 years.

Duration

The status of the Campbell Duck is classified as severely threatened. Rats that eat the eggs and chicks would have caused the last of the species to become extinct if they had reached Dent Island from Campbell Island. The population of brown rats on the main island was estimated at one million individuals before the eradication campaigns began. In order to preserve the very endangered duck in its population, the New Zealand nature conservation authority started a conservation breed . In 1999 this breeding group comprised 52 campbell ducks. They go back to a total of 11 ducks (8 male, 3 female) that were caught on Dent Island. All of the descendants of the breeding group descend from just one female, the other two did not breed. The genetic variation is among the lowest in wild birds.

The first reintroduction measures began in 1999 and 2000. In both years twelve ducks were released into the wild. Codfish Island , a small South Pacific island west of Stewart Island in southern New Zealand , was used as a release site . It is 14 km²; the highest point at 249 m above sea level is located near the south coast. The island is uninhabited. At times, some biologists live at Sealers Bay . The only means of transport to the outside world is the helicopter , which is supposed to prevent accidental introduction of rats. Codfish Island is a bird sanctuary and primarily serves to protect the kakapo , an endangered flightless bird from the family of the true parrots (Psittacidae), the population of which has declined sharply in the last century. The introduction of the Campbell Duck on Codfish Island was successful. Eggs were laid in the first year.

In 2001 the brown rats that were introduced to Campbell Island were completely exterminated. In March 2003, Campbell Island, once considered the most densely populated area in the world, was declared rat-free. In September 2004, 50 camp ducks were released on this island. A second release of 55 ducks took place in September 2005. The majority of the ducks released in 2004 appear to have survived their first year on Campbell Island. The first evidence of successful reproduction on this island is from 2006. Chicks were observed in January 2006 and a little later one chick, three young ducks and two nests with eggs. Including the camp ducks kept in human care and the small populations on Dent Island and Codfish Island, the population of this duck is now back to 200 to 300 individuals.

habitat

On Dent Island, the Campbell duck mainly uses the eastern slopes of the island, which are covered with bluegrass and ferns. She shows a preference for shallow gullies that run between the clump grasses and ferns. It uses the earthworks that petrels create for their breeding and moves mainly in the protection of the low vegetation. In doing so, she uses the paths that the petrels have tread between the grass groves. The almost closed stalk roof of the eyrie grasses offers protection from the weather as well as from predators. It is believed that it originally used a wider range of habitats on Campbell. The closely related Auckland duck can also be found in ironwood forests and it is obvious that the Campbell duck will also develop comparable habitats on the now repopulated Campbell Island in the medium term.

Way of life

Very little is known about the way of life of wild camp ducks. The Auckland duck is very territorial. Since territorial pairs could also be observed in the Campbell Duck in December, February and June, it is assumed that this behavior also applies to the Campbell Duck. Both sexes respond to the calls of other ducks and drive intruders from their territory. The diet is also unknown. However, it is presumably dominated by amphipods and insects.

Campbell ducks held in human care brooded from October to January. The laying interval was three days. The shell color of the eggs is pale brown. The average clutch size is 3.8 eggs. The female breeds alone. The incubation period is 30 to 34 days. Young ducks reach the weight and wing length of adult campbell ducks on average by the 63rd day of life.

literature

  • PJ Higgins (Eds.): Handbook of Australian, New Zealand & Antarctic Birds , Volume 1, Ratites to Ducks, Oxford University Press, Oxford 1990, ISBN 0-19-553068-3
  • Janet Kear (Ed.): Ducks, Geese and Swans . Oxford University Press, Oxford 2005. ISBN 0-19-854645-9
  • Hartmut Kolbe: The world's ducks. Ulmer, Stuttgart 1999. ISBN 3-8001-7442-1

Web links

Commons : Campbellente ( Anas nesiotis )  - Collection of images, videos and audio files

Individual evidence

  1. BirdLife Factsheet on Campbell Duck , accessed April 13, 2011
  2. ^ Higgins, p. 1300
  3. Kear, pp. 581, 582.
  4. a b c Kear, p. 582.
  5. a b Kolbe, p. 239.
  6. a b Kear, p. 583.
  7. ^ Campbell Island teal | New Zealand Birds Online. In: nzbirdsonline.org.nz. Retrieved October 13, 2016 .
  8. a b Birdlife Fact Sheet about the Campbell Duck accessed on February 14, 200
  9. Kolbe, p. 240.