Auckland shard
| Auckland shard | ||||||||||||
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Auckland shark ( Leucocarbo colensoi ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Leucocarbo colensoi | ||||||||||||
| ( Buller , 1873) |
The Auckland shark ( Leucocarbo colensoi , Syn . : Phalacrocorax colensoi ) is a species of bird from the cormorant family . The black and white, slender species occurs exclusively on New Zealand's Auckland Islands , a sub-Antarctic archipelago. The IUCN classifies the Auckland shag as endangered ( vulnerable ) and estimates the population at 2000 sexually mature individuals.
Appearance
The Auckland shear reaches a body length of 63 centimeters, the wingspan is 105 centimeters. There is no noticeable sexual dimorphism , but the sexes can be distinguished on the basis of their different vocalizations and their deviating behavior during courtship.
In the splendid dress the head and the back neck are black with a bluish tinge. The throat and front neck are white, the forehead feathers are elongated to form a bonnet and curl forward. The top of the body is bluish black, the control feathers are black. The underside of the body is white. The bill is black-gray during courtship, the tip of the lower bill is orange. The eye ring is shiny purple, the rest of the feathered facial skin is dark purple to dull red. The throat pouch is orange-red. The iris is dark purple or brown. The feet and legs are orange, the soles of the feet are dark gray and the claws are black. The feather bonnet is missing in the simple dress , the black plumage fades to a brownish hue during the breeding season. The beak is dark brown, the eye ring is pink to pale purple. Young birds have a brownish plumage that has a greenish sheen. The featherless skin of the face is brown.
The Auckland shark can only be confused with a few other species of cormorant: Both the Australian dwarf shark and the common cormorant occasionally reach the Auckland Islands as random visitors . Both have longer wings and longer control springs. The feet of these species are black, unlike the Auckland shear.
On land, Auckland shags move skillfully. Typical for them is an upright posture and a walk in which they lift their feet noticeably high. Auckland shards fly with the neck and head stretched forward, the head being below the line that forms the body axis.
distribution and habitat
The Auckland Islands are about 465 km south of New Zealand's South Island . The total land area of the archipelago is 606 km², of which 510 km² are on the main island of Auckland Island . The second largest island in the group is Adams Island , south of the main island , the third largest is Enderby Island, north of the main island, and the fourth largest is Disappointment Island, west of the main island . Breeding colonies of the Auckland Shear are on the main island of Auckland, Enderby and Adams Island and on the two smaller islands Rose and Ewing. Auckland shags forage in the waters around these archipelagos, usually no more than 15 miles from the coastline.
Way of life
Auckland shags eat small fish and crustaceans. The way of life is otherwise very little studied. They nest in both small groups and large colonies between tufts of grass, on ledges and high cliffs. They prefer nesting locations that offer some privacy due to overhanging rocks or higher vegetation. This protects both the clutch and the young birds from predators such as skuas . At locations where they breed between tufts of grass, they give up the colony location when the vegetation dies due to the excrement. The nest is mainly made of grass, but small twigs, seaweed, moss and washed-up rubbish are also built in. The respective breeding pair only defends the immediate vicinity of the nest. The nests are about 75 centimeters apart.
The clutch size has not yet been conclusively investigated, but clutches probably consist of an average of three eggs. The laying interval is 48 to 96 hours. Both parent birds breed. The male parent bird breeds in the morning, the female returns in the middle of the day, the male then leaves the nesting site and returns at dusk. The breeding season is between 28 and 32 days. Newly hatched chicks are initially naked and later covered with gray dunes. Nestlings are fed by both parent birds.
Danger
The last exact counts were made in 1988 and 1989. 11 colonies with a total of 475 nests were counted on Enderby, one breeding colony with 62 nests on Rose and 306 on Ewing. No censuses are available for Auckland Island.
On Auckland Island, the main island in the archipelago, the main threat to Auckland shags comes from feral domestic pigs, which destroy every breeding colony they can reach. As a result, all of the breeding colonies on Auckland Island are in inaccessible locations. On the Auckland Island, feral domestic cats are a potential danger for Auckland shags. On Rose and Enderby, feral domestic cattle trample the nests, the domestic cattle have also destroyed a type of grass that was formerly used most often by Auckland shags.
supporting documents
literature
- PJ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds. Volume 1, Ratites to Ducks, Oxford University Press, Oxford 1990, ISBN 0-19-553068-3 .
Web links
- BirdLife International to Auckland Scharbe
- Leucocarbo colensoi inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved January 30, 2014.
Single receipts
- ↑ BirdLife International on Auckland Scharbe , accessed May 14, 2011
- ^ Higgins: Handbook of Australian. 1990, p. 885.
- ↑ BirdLife International on Auckland Scharbe , accessed May 14, 2011
- ^ Higgins: Handbook of Australian. 1990, p. 887.
- ^ Higgins: Handbook of Australian. 1990, p. 886.
- ^ Higgins: Handbook of Australian. 1990, p. 887.
- ↑ BirdLife International on Auckland Scharbe , accessed May 14, 2011
- ↑ BirdLife International on Auckland Scharbe , accessed May 14, 2011