Lesser black-backed gull

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The lesser black-backed gull (Larus fuscus) is a large gull that breeds on the Atlantic and Arctic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa. However, it has increased dramatically in North America, especially along the east coast. Formerly just a winter visitor to North America, it now occurs in large numbers some winters and birds are recorded year-round.[1] However, there is serious concern about decline in many parts of its range. The species is on the UK Amber List[2] because the UK is home to 40 per cent of the European population and more than half of these are found at fewer than ten breeding sites.[2]

Taxonomy

The lesser black-backed gull was one of the many species originally described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, and it still bears its original name Larus fuscus.[3] The scientific name is from Latin. Larus appears to have referred to a gull or other large seabird, and fuscus meant black or brown.[4]

Subspecies

Five subspecies are accepted:[5]

Image Subspecies Distribution
File:Larus fuscus on the wall of Mont St Michel.jpg L. f. graellsii Brehm, 1857 Greenland, Iceland, Faroe Islands, British Isles, western Europe - mantle dark grey
File:Larus fuscus EM1B1660 (40890382754).jpg L. f. intermedius Schiøler, 1922 Netherlands, Germany, Denmark, southwest Sweden and western Norway - mantle sooty black
File:Larus fuscus, a gull in Helsinki, Finland, 2020 August.jpg L. f. fuscus Linnaeus, 1758 northern Norway, Sweden and Finland to the White Sea - mantle jet black
File:Sea-Gull.jpg L. f. heuglini Bree, 1876 northern Russia to north-central Siberia; known as Heuglin's gull, this was previously considered a separate species.
File:Чайка на фоне оголившихся корней сосны.jpg L. f. barabensis Johansen, 1960 central Asia

Description

The lesser black-backed gull is smaller than the European herring gull. The taxonomy of the herring gull / lesser black-backed gull complex is complicated; different authorities recognise between two and eight species. This group has a ring species distribution around the Northern Hemisphere. Differences between adjacent forms in this ring are fairly small, but by the time the circuit is completed, the end members, herring gull and lesser black-backed gull, are clearly different species.

The lesser black-backed gull measures Script error: No such module "convert"., Script error: No such module "convert". across the wings, and weighs Script error: No such module "convert"., with the nominate race averaging slightly smaller than the other two subspecies.[6] Males, at an average weight of Script error: No such module "convert"., are slightly larger than females, at an average of Script error: No such module "convert".. The wing chord is Script error: No such module "convert"., the bill is Script error: No such module "convert"., and the tarsus is Script error: No such module "convert"..[7][8][9] A confusable species is the great black-backed gull. The lesser is a much smaller bird, with slimmer build, yellow rather than pinkish legs, and smaller white "mirrors" at the wing tips. The adults have black or dark grey wings (depending on race) and back. The bill is yellow with a red spot at which the young peck, inducing feeding (see fixed action pattern). The head is greyer in winter, unlike that of the great black-backed gull. The annual moult for adults begins between May and August and is not complete on some birds until November. A partial prebreeding moult occurs between January and April.[10]

Young birds have scaly black-brown upperparts and a neat wing pattern. They take four years to reach maturity. Identification from juvenile herring gulls is most readily done by the more solidly dark (unbarred) tertial feathers.

Their call is a "laughing" cry like that of the herring gull, but with a markedly deeper pitch.

Distribution

Lesser black-backed gulls have expanded their range westwards, first colonising Greenland in the 1980s. The species has not yet bred in the United States, although hybrid pairs with American herring gulls have been recorded twice.[1]

Breeding

This species breeds colonially on coasts and lakes, making a lined nest on the ground or a cliff. Normally, three eggs are laid. In some cities, the species nests within the urban environment, often in association with herring gulls.[11]

File:Larus fuscus MWNH 0325.JPG
Eggs, collection Museum Wiesbaden

Feeding

They are omnivores, like most Larus gulls, and eat fish, insects, crustaceans, worms, starfish, molluscs, seeds, berries, small mammals, eggs, small birds, chicks, scraps, offal, and carrion.


Gallery

References

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  10. ↑ RSPB Handbook of British Birds (2014). UK Template:ISBN
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External links

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