Lesser Black-backed Gull (Larus fuscus)

[order] CHARADRIIFORMES | [family] Laridae | [latin] Larus fuscus | [UK] Lesser Black-backed Gull | [FR] Goeland brun | [DE] Heringsmowe | [ES] Gaviota Sombria | [NL] Kleine Mantelmeeuw

Subspecies

Physical charateristics

Large but quite elegant gull, smaller of two black-winged and black-backed species in west Palearctic. Adult of northernmost race has back almost as black as flight feathers, but in southern races back becomes paler, even approaching in British birds ash-grey of Yellow-legged Gull and then contrasting with black flight feathers. Adult plumage otherwise white, with dusky streaks on rear head and neck in winter progressively more obvious from north to south. In all seasons, undersurface of flight feathers shaded (unlike Herring Gull). Legs yellow, even orange in spring. Juvenile noticeably darker than young Herring Gull, with more uniform dark brown mantle, darker unbarred tertials and outer greater coverts and (conversely) cleaner surround to bill and nape. In flight, first winter separable from Herring Gull by almost uniformly black-brown outer wing, greater coverts, and secondaries, and much deeper and more cohesive dark band across tail contrasting with whiter rump; less easy to tell from Yellow-legged Gull, which shows only faintly paler inner primaries (unlike Herring Gull) but has distinctively paler head than both other species.

Listen to the sound of Lesser Black-backed Gull

[audio:http://www.aviflevoland.nl/sounddb/L/Lesser Black-backed Gull.mp3]

Copyright remark: Most sounds derived from xeno-canto

Range

Eurasia : West Europe to Central Northern Siberia; also Greenland and Iceland

Habitat

Breeds mainly within oceanic fringe of middle and higher latitudes of west Palearctic, in temperate and boreal zones, extending marginally through subarctic to low-arctic coasts, but avoiding icy seas. In contrast to Great Black-backed Gull, often occupies nest-sites readily accessible over land to man and to mammalian predators, depending for security on strength of numbers in colony and on human tolerance or protection, accompanied by a degree of remoteness from settlements; exceptions are rocky islands, where grassy summit areas away from shore favoured, and islets in freshwater lakes. Generally flat or sloping sites under close, fairly short vegetation preferred.
Outside breeding season, spreads much more widely over inland and marine habitats, chiefly in inshore or offshore seas down to tropical waters, where it frequents lagoons, estuaries, harbours, and seashore, but often occurring inland. When wintering in England, strongly prefers gravel ponds and reservoirs or estuaries, docks, upper beaches of mud or shingle, sports fields, floodlands, river weirs, canals, filter beds, and sometimes ploughed fields near towns.

Reproduction

North Sea area: egg-laying from late April or early May; up to 2 weeks later in Iceland and Finland. Nest is built on ground in the open, or partly sheltered by vegetation, sometimes more or less concealed in tall growth; also on cliff-ledges and -tops; since c. 1945, on roofs and ledges of buildings. Nest is a fairly substantial mound of seaweed, grasses, other vegetation, and general debris, 25-35 cm in external diameter and 10-15 cm high, with central depression 15-18 cm in diameter and 4-8 cm deep, lined finer material; less often shallow scrape with sparse lining. Clutch size 3 (1-4), incubation period
24-27 days and the chicks fledge after about 30-40 days. Colonies usually small in Russia, but large in Britain.

Feeding habits

Fish, aquatic invertebrates, nestlings and eggs of birds, carrion, offal, rodents and berries.
Baltic herring important in diet. In Mediterranean, prefers trawler discards, but during trawling moratorium fed at rubbish dumps, olive groves and rice fields.
Methods include contact-dipping and surface-plunging. In intertidal zone, more likely to peck at visible food items than to rummage in seaweed or under stones.

Conservation

This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Migration

Basically migratory, though in recent decades 2nd-winter and older birds have shown increased tendency to winter within Britain. Total winter range now extends from Britain, Mediterranean, Black and Caspian Seas (uncommon), Turkmenistan, and Persian Gulf to Arabian Sea and West and East Africa (sparingly further south). Eastern populations in particular have extensive overland migrations.

Distribution map