Black-billed Gull
| Black-billed Gull | ||||||||||||
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Black-billed Gull ( Leucophaeus scoresbii ) |
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| Leucophaeus scoresbii | ||||||||||||
| ( Traill , 1823) |
The dolphin gull ( Leucophaeus scoresbii , Syn. : Larus scoresbii ) is a monotypic gull species , which is found in southern South America. It is a medium-sized gull with a short but very strong beak, which is strikingly red in color in adult birds. It cannot be confused with any other species of gull in its range. The also white-headed and white-tailed Dominican gull , which occurs in the same range, is considerably larger.
Appearance
The black-billed gull reaches a body length between 40 and 46 centimeters. The wing length is 30.6 to 33.9 centimeters, the wingspan between 104 and 110 centimeters. On average, the animals weigh 524 grams. Males are, on average, slightly larger than females.
Adult black-billed gulls are unmistakable in their splendid dress . They then have a white head and a white underside of the body that is slightly greyish. The trunk and tail are somewhat whitish. The wings are black, but they have a wide white feather border at the end, which is particularly noticeable in flight. The arm wings are a bit greyish underneath. The legs and beak are bright red. The yellowish-white eye is surrounded by a striking red eye ring. In the plain dress the head is grayish.
Fledglings have a gray-brown head and an equally colored upper chest, which sets them apart from all other species of gulls. The belly is white, the back and the upper side of the wings is black-brown. A dark transverse band runs on the tail feathers. Not yet sexually mature individuals towards the end of the first year of life are still like young birds, but already have a whitish breast and throat. Two- and three-year-old birds show an increasing resemblance to the adult birds, but still have a dark skull and the neck is still dark in color. In the second summer, the iris already shows the coloring of the adult birds.
Distribution area
The distribution area of the black-billed gull includes the coasts of southern Chile and southern Argentina to Tierra del Fuego , as well as the islands of Cape Horn and the Falkland Islands . Blood-billed gulls migrate a little further north during the winter months.
Way of life
Blood-billed gulls are omnivores, but mainly feed on carrion, bird eggs and their chicks. They also eat marine invertebrates , clams, and insects . During their foraging, they regularly search seaweed washed up on the beach. They also hunt other seagulls and cormorants for food.
Black-billed gulls are colony breeders. The colonies are usually relatively small and are regularly associated with Dominican gulls . The breeding season begins at the beginning of November at the earliest, but usually not until December. The nest is set up protected between boulders or tufts of grass. It consists of seaweed or other plants, the nesting trough is usually covered with grass. The clutch consists of two to three eggs. These have a gray-greenish to olive-beige color. The breeding season is 24 to 27 days. The chicks leave the nest at two to five days old and form groups of children when they are a little older.
supporting documents
literature
- Hadoram Shirihai: A Complete Guide to Antarctic Wildlife - The Birds and Marine Mammals of the Antarctic Continent and Southern Ocean . Alula Press, Degerby 2002, ISBN 951-98947-0-5
Single receipts
Web links
- Larus scoresbii inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved January 14, 2014.