Simeon's Gull

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Simeon's Gull
Adult Simeon's gull (Larus belcheri) in breeding plumage

Adult Simeon's gull ( Larus belcheri ) in breeding plumage

Systematics
Class : Birds (aves)
Order : Plover-like (Charadriiformes)
Family : Laridae
Subfamily : Seagulls (larinae)
Genre : Larus
Type : Simeon's Gull
Scientific name
Larus belcheri
Vigors , 1829
Flying Simeon Gull (adult) in simple dress . The black tail band is clearly recognizable - a feature that most other species of the genus Larus only show in their juvenile clothes.

The Belcher's Gull or Schwanzbandmöwe ( Larus belcheri ) is a bird art within the gulls (Larinae). It inhabits the west coast of South America in the area of ​​the Humboldt Current .

The very similar olroggull ( Larus atlanticus ) from the east coast of South America has long been considered a subspecies of the Simeon's gull. Both belong within the genus Larus to a rather original group of four species that wear a dark tail band in all clothes and show relatively simple beak drawings and almost completely black hand wings in adult dress.

The specific epithet honors the British navigator Sir Edward Belcher , who collected the first specimen of this species.

description

With a length of 48–52 cm and a wingspan of 120 cm, the Simeon's gull is somewhat smaller than a herring gull . However, with its head shape and powerful beak, it is reminiscent of larger seagulls. The species differs from the very similar Olroggull by shorter wings, a shorter beak with a less pronounced gonys angle , a blurred transition from the coat to the neck and a more brownish top.

In breeding plumage the head, neck and bottom are white. The yellow beak has a wide, black subterminal ring in front of the red tip . The dark iris is framed by a red orbital ring. The plumage on the upper side is brown-black and blends into the white of the neck at the nape. The inner wing part shows a white trailing edge. The hand wing is almost completely black and, apart from the inner hand wings, has no white tips and no conspicuous pattern as in other Larus species. The white tail wears a wide, black subterminal band. Feet and legs are yellow.

In winter plumage, adult Simeon gulls show a dark head, the color of which on the upper neck blends into the white of the underside. Narrow, white half-rings around the eye stand out from this.

In the youth dress the head is soot-brown, the bill yellow with black tip. The underside is gray-brown with a lighter underbelly. The dark plumage on the coat and shoulders looks like scales due to light hems. The cover plumage of the wings and the umbrella feathers show only a diffuse pattern on a dark background. The inner wing trailing edge is whitish. The tail is black, the legs are dark brown to dark flesh-colored.

In the first winter, the coat and shoulders become lighter, the spring centers are less expanded. The dark head contrasts strongly with the yellow beak and the light underside.

In the second winter, the coat and shoulders already turn brown-black, like in adult birds, the upper wing-coverts, which are still brown, stand out from it. The head cap is also similar to that of adult birds, but the transition to the neck is more diffuse. The beak is almost completely colored, but the red tip is not yet as intensely red as in older birds.

voice

The calls of this kind are described as a short, clear jap or jiau . The " long call " (audio sample) is an increasing series of calls made of clear sounds.

Distribution and existence

The monotypical Simeon's gull colonizes the west coast of South America in the area of ​​the Humboldt Current, where the brood distribution ranges from the Peruvian region of La Libertad to the northern Chilean region of Tarapacá . Outside the breeding season, the species can be found north to northern Ecuador and south to central Chile.

The world population is estimated at less than 100,000 breeding pairs and only a small number of larger breeding sites are known. The species is quite common in Peru. A large part of the breeding population is concentrated in the area of ​​the island of San Gallán in central Peru. The species is classified by the IUCN as not endangered (“least concern”).

hikes

The Simeon's gull is presumably largely a resident bird , but there are occasional dismigration movements in the area of ​​the Humboldt Current to the north and south. The species was found to be a stray visitor in Panama and Florida .

Way of life

The Simeon's gull feeds on fish, crustaceans and carrion. During the rearing of the young, bird eggs and nestlings of other species are important. The food is sought on beaches, in the intertidal zone and in seabird colonies. The species rarely follows ships out to sea.

The breeding colonies are located on rocky stretches of coast and on coastal guano islands and are occupied from December. They are usually less than 100 pairs in size. In a few places the number exceeds 1000 breeding pairs. The nesting sites are in rock niches or in the sand. The eggs are often laid there without a nest being built. The clutch usually consists of 3 dark olive-brown eggs.

Individual evidence

  1. ↑ Andrew Spencer: XC47018 · Black-tailed Gull · Larus belcheri . xeno-canto.org. November 29, 2009. Retrieved October 30, 2019.
  2. ↑ Schulenberg et al. (2007), p. 148, see literature
  3. ↑ a b Del Hoyo et al. (1996), see literature
  4. ↑ Olsen / Larsson (2003), p. 583, see literature

literature

Web links

Commons : Simeon's gull ( Larus belcheri )  - Collection of images, videos and audio files