- Morus bassanus
Identification
Northern Gannet Sula bassana
The Northern Gannet (Morus bassanus, formerly Sula bassana) is a large seabird of the gannet family, Sulidae. Young birds are dark brown in their first year, and gradually acquire more white in subsequent seasons until they reach maturity after five years.
Adults are 87-100 cm long and have a 165-180 cm wingspan. Their plumage is white with black wing tips. The bill is light bluish. The eye is light blue, and it is surrounded by bare, black skin. During breeding, the head and neck are brushed in a delicate yellow.
Distribution
Their breeding range is the North Atlantic. They normally nest in large colonies, on cliffs overlooking the ocean or on small rocky islands. The largest colony of this bird, with over 60,000 birds, is found on Bonaventure Island, Quebec, but 68% of the world population breeds around the coasts of Great Britain, with the largest colonies on the Bass Rock (where the species obtained its name) and Boreray, St Kilda. They are migratory and most winter at sea, heading further south in the Atlantic.
Over 70% of the world population of Northern Gannet breed in more than 20 colonies around the coasts of the British Isles and in particular off north and west Scotland. The world's largest gannetry is on St Kilda with over 50,000 pairs. There are also colonies on the Flannan Islands to the west of the Outer Hebrides, further north on remote Sula Sgeir, and Sule Stack to the west of the Orkneys. Shetland has long-established colonies on Noss and Hermaness with more recent breeding on Foula and Fair Isle. Further south in Scotland there are large gannetries on Bass Rock in the east and Ailsa Craig in the west and two smaller, more recently established colonies on Scar Rocks off the Mull of Galloway and Troup Head, Grampian. England's only remaining colony is on Bempton Cliffs, North Yorkshire and the single Welsh site is the island of Grassholm, off Dyfed where more than 30,000 nest. Ireland has five gannetries, Little Skellig off County Kerry is the largest with more than 20,000, Bull Rock , County Cork and Great Saltee, County Wexford are much smaller with less than 2,000 each, and the smallest are Clare Island, County Mayo and the newly-founded Ireland's Eye colony off County Dublin. In the English Channel there are breeding Gannets on Ortac and Les Etacs off Alderney in the Channel Islands and the most southerly colony in Europe is on Ile Rouzic in the Sept Iles off Brittany. Elsewhere in Europe there are six gannetries in Iceland including the Westmann Islands, one on Mykinesholmur in the Faroes and 6-7 in Norway. All the Norwegian gannetries are relatively recently established and include Norway's first, at Runde in the south and the world's most northerly, at Syltefjordstauran. One in the Lofoten Islands has been abandoned probably through persecution. Breeding has recently occurred for the first time on the Murman coast of Russia and the first breeding for Germany took place on Heligoland in 1991 with more than 90 pairs by 2000. In 1996 the first breeding in the Mediterranean occurred at Bendol, Var in southern France. In North America breeds mainly on the Gasp Peninsula of Quebec and Newfoundland. After breeding Gannets disperse, some remain at sea within breeding latitudes but others move south to Biscay, off Iberia and south to West African waters. In winter also found in the Mediterranean, mainly east to Italy but a few wander as far as Cyprus and beyond. North America birds winter on the eastern seaboard from New Jersey south to Florida and in the eastern Gulf of Mexico. Vagrants recorded north to Svalbard, the Baltic States and Poland and even to land-locked countries such as Austria and Switzerland.
Taxonomy
Habitat
Breeding colonies are located on isolated stacks or remote islands, sometimes on mainland cliffs. At sea when not breeding, over continental shelf. Occasionally on large inland waters as a result of severe weather.
Behaviour
Gannet pairs may remain together over several seasons. They perform elaborate greeting rituals at the nest, stretching their bills and necks skywards and gently tapping bills together. These birds are spectacular divers, plunging into the ocean at high speed. They mainly eat small fish which gather in groups near the surface. Although they are powerful and agile fliers, they are clumsy in takeoffs and landings. Although Northern Gannet populations are now stable, their numbers were once greatly reduced due to loss of habitat, removal of eggs and killing of adults.
