Ring-billed gull
| Ring-billed gull | ||||||||||||
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Ring- billed gull ( Larus delawarensis ) in splendor |
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| Larus delawarensis | ||||||||||||
| Ord , 1815 |
The ring-billed gull ( Larus delawarensis ) is a North American species of bird within the seagulls . It can also be found in Europe as an exception .
features
The ring-billed gull reaches a body length of 41 to 49 centimeters and a wingspan of 112 to 124 centimeters. It is slim and has a large head, the top of which is evenly curved. The long, narrow wings are pointed at the end, arm and hand wings are about the same length. The tail is short and straight at the rear edge. The back toe no longer touches the ground. The beak is relatively short and thin, but like a herring gull with a hook-like tip and protruding gony corner .
The ring-billed gull is a so-called three-year-old gull, that is, it puts on the complete plumage of the adult birds after three years. Adult birds have light gray backs and light gray wings. The arm wings have a white rear edge. The tips of the hand wings are black, they have four small spots arranged lengthways on the wing and a larger white spot just before the wing tip on the wing leading edge. The rest of the plumage is white. Feet and iris are yellow. The eye is surrounded by a narrow, red and featherless lid ring. In the splendid dress the head is pure white and the yellow beak has a black cross band in front of the tip. In front of this ring, the tip of the beak is light yellow to beige. In the plain dress, the beak shaft is greenish yellow or grayish yellow. The head and neck now have gray-brown lines. The areas behind the eye or the ear covers adjacent to the neck are particularly drawn. Otherwise the simple dress resembles the magnificent dress .
When young, the bird is almost uniformly gray-brown in color or speckled, only the head, belly and rump are whitish. The hand wings are black-brown and without the white spots, the rest of the wing is brown and looks scaly because the feathers are black to dark brown in color. The tail has a wide, slightly diffuse end band at the edges, which has a white, narrow rear edge. The feet are dirty gray-beige. The entire tip of the beak is black, the beak shaft is brown-beige. In the first winter dress, the plumage is only dashed, no longer flat brown. The hand swing and tail still show the appearance of this in youth dress. The white-edged umbrella feathers and the front arm wings are completely brown. There are also some brown spots on the back and under wing. Legs and beak are light beige, the tip of the beak is black except for a small point directly at the end of the beak.
In the first summer dress, the lines on the stomach and chest have disappeared. The arm wings are almost entirely gray. The black tail band is pale. The beak has the same coloration as in the first winter, but has a distinctly light tip and a dark ring behind it. The second winter dress contains completely gray wings with a white rear edge. Not only the tip of the wing is slightly black, but also the inner part, which is not visible when the wing is folded. The tail band has almost come off. Feet and beak are green-yellow, the beak has a ring. In the second summer dress, the tail band has finally disappeared and the gray-brown dotted lines are missing on the head and neck, so it is only present on the flanks. The hand wings are still covered in black in the inner part. The beak and legs are green-yellow as in the second winter dress.
Possible confusion
The ring-billed gull is very similar to the Eurasian common gull . Important distinguishing features from common gulls are: the beak and body are stronger, the feet are longer, the gull is slightly larger overall. In its magnificent dress, the common gull lacks the black beak ring (but this is present in all other clothes). In the plain dress, the beak ring is thinner and the beak shaft is greener. In the 1st and 2nd winter plumage as well as in the 1st and 2nd summer plumage, the two types can only be distinguished by their physique. The iris of the common gull is never yellow, but always brown. Another possibility of confusion is the herring gull in the 2nd winter plumage with the ring-billed gull in the 1st winter plumage. The herring gull , however, is much larger and even stronger and has variably striped or spotted large arm covers and umbrella feathers, while these feathers in the ring-billed gull are relatively monochrome.
Way of life
The ring-billed gull shows the same call patterns as the herring gull, but higher and more nasal. She often paces back and forth in search of food. Their food spectrum ranges from fish to invertebrates such as insects , echinoderms , worms , snails and mussels to carrion. Fish are actively caught from the water, while worms and insects, for example, are caught in meadows. Similar to the herring gull and the black-headed gull , it also finds food in cities, such as in landfills. Mollusks and other invertebrates are searched for in the flushing fringes on coasts and banks. During the breeding season, the bird can be found on inland lakes and small bodies of water, where it also breeds. The nest is built on the ground in denser or sparse vegetation. It consists of parts of plants such as grass, reeds, leaves and others and is a slightly conical, messy pile with a hollow in the middle. The seagull breeds in colonies. In the winter months it is more common on the coast.
Habitat and Distribution
The ring-billed gull is common in much of North America. Their preferred breeding areas are lakes and reservoirs. The breeding area extends from southern Canada to the central United States . The northern border is a line from Vancouver Island to the Great Slave Lake , from there to Hudson Bay and then to the Labrador Peninsula to north of Newfoundland . In winter the birds migrate south. The wintering area is the southern USA at the height of Florida and California via Mexico and Central America to the Caribbean , the Bahamas and the Greater Antilles . It also rarely comes to Alaska , Ecuador , Panama , Venezuela , Colombia , Brazil , South Africa , Japan , South Korea , Mauritania , Morocco , Senegal and some Atlantic and Pacific islands, such as Hawaii , the Azores and Bermuda .
In Europe, it is particularly to be found in the west as a guest bird, for example in Portugal , Spain , France and Great Britain ; Most of the sightings are in the winter months. In Central and Northern Europe, where it has been observed in Belgium , the Netherlands , Germany , Denmark , Poland , Sweden , Norway and Iceland , the species is a rare exception.
The IUCN classifies it as least concern (not endangered).
photos
Plain dress
Youth dress
Calling young bird in 1st summer dress
2. Winter dress
literature
- Colin Harrison & Alan Greensmith: Birds . Ravensburger Buchverlag, Otto Maier GmbH, 1994, ISBN 3-473-46076-1
- Svensson, Grant, Mullarney, Zetterström: The new cosmos bird guide . Franckh-Kosmos Verlags-GmbH & Co. KG, Stuttgart 1999, ISBN 3-440-07720-9
Web links
- Avibase
- Birdlife international
- Larus delawarensis inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved January 14, 2014.
- Ring-billed gull feathers