The northern gannet (Morus bassanus) is a seabird and the largest member of the gannet family, Sulidae. It is native to the Atlantic Ocean, breeding in Western Europe and North America. The sexes are similar in appearance. The adult northern gannet has a mainly white streamlined body with long neck, long and slender wings and long pointed bill. It is 81-110 cm (32-43 in) long with a 165-180 cm (65-71 in) wingspan. Nesting takes place in colonies both sides of the north Atlantic, the largest of which are at Bass Rock (75,000 pairs), St Kilda (60,000 pairs) and Ailsa Craig (33,000 pairs) in Scotland, Grassholm in Wales, and Bonaventure Island (32,000 pairs) off the coast of Quebec. This bird undertakes seasonal migrations and is a spectacular high-speed diver. Fish form the bulk of its diet. This bird is considered to be a least-concern species according to the International Union for Conservation of Nature (IUCN)
Video Northern gannet
Taxonomy
Swiss naturalist Conrad Gessner described the northern gannet as Anser bassanus or scoticus in the 16th century, noting that the locals called it "solendguse". The former name was also used by English naturalist Francis Willughby wrote about the northern gannet in the 17th century, known to him from a colony in the Firth of Forth and a stray bird that was found near Coleshill, Warwickshire. It was one of the many species originally described by Swedish zoologist Carl Linnaeus in the landmark 1758 10th edition of his Systema Naturae, where it was given the binomial name of Pelecanus bassanus. Brisson placed it in the genus Sula in 1760, while Louis Jean Pierre Vieillot established the new genus Morus in 1816, placing it within. Morus is derived from Ancient Greek moros, "foolish" due to the lack of fear shown by breeding gannets and boobies allowing them to be easily killed. The specific name bassanus is from the Bass Rock in the Firth of Forth, which holds the world's largest colony of northern gannets.
"Northern gannet" has been designated the official name by the International Ornithologists' Union (IOC). It is also known as the North Atlantic gannet. "Gannet" is derived from Old English ganot "strong or masculine", ultimately from the same Old Germanic root as "gander". "Soland goose" and similar old names for the northern gannet such as "solan" or "solan goose" derive from a hypothetical Scotish Gaelic sulan, itself borrowed from Old Norse sula. The literal meaning is "cleft stick", referring to the appearance of the conspicuous crossed black wing tips. Old regional names such as Norfolk's "herring gant" or Yorkshire's "mackerel gant" refer to typical fish prey. Lincolnshire "gaunt", although derived from the same Germanic root, usually applies to the great crested grebe, but English writer Richard Hakluyt used the term in 1600 to refer to the gannet, "a great White foule". Young birds have been called spotted booby or parliament goose, referring to their plumage.
The Sulidae, the gannets and boobies, appeared about 30 million years ago. Early Sulidae fossils most resembled the boobies, although they were more aquatic, with the gannets splitting off later, about 16 million years ago. The gannets evolved in the northern hemisphere, later colonising the southern oceans. The most ancient extant species may be the Abbott's booby, possibly the sole survivor of an otherwise extinct separate lineage. A 2011 genetic study of nuclear and mitochondrial DNA suggests that the ancestor of the gannets arose around 2.5 million years ago before splitting into northern and southern lineages. The latter then splitting into the Cape and Australasian gannets around 0.5 million years ago.
Maps Northern gannet
Description
An adult northern gannet is 81-110 cm (32-43 in) long, weighs 2.2-3.6 kg (4.9-7.9 lb) and has a 165-180 cm (65-71 in) wingspan, making it the largest seabird native to the western Palearctic. The two sexes are generally of a similar size and appearance. The plumage is white with dark brown to black wing tips; the primary flight feathers, primary coverts and alulae are dark. The head and neck are tinged buff-yellow, becoming much more prominent in the breeding season. Males are more deeply coloured than females. The eyes have a light blue to light grey iris surrounded by a thin black ring of bare skin. The beak is long, strong and conical with a slight downward curve at the end. The front part has a sharp edge. In adults, the beak is blue-grey with dark grey or black edges. There is a black groove running the length of the mandible that merges into the skin around the eyes. A black band of bare skin also separates the pale feathers of the forehead and throat from the bill, which gives the gannet its distinctive face markings. The four toes of their feet are joined by a membrane that can vary from dark grey to dark brown. There are coloured lines running along the toes that continue along their legs. These are typically greenish-yellow in males and bluish in females and probably have a role in mating. The rear toe is strong and faces inwards allowing the birds to firmly grip onto vertical cliff faces.
Fledglings are dark- to slate-grey with upperparts and wings finly speckled with white. There is a prominent v-shaped white area under the rump. The wing tips and tail are dark brown-black, partly tipped with white. The bill and iris are dark brown. They can weigh more than 4 kg (8.8 lb) by the time they leave the nest at about 10 weeks of age. In the second year the birds' appearance changes depending on the different phases of moulting: they can have adult plumage at the front and continue to be brown at the rear. Gannets gradually acquire more white in subsequent seasons until they reach maturity after five years.
Individuals on the west coast of Africa could be confused with vagrant masked boobies, though the latter is smaller overall, lacks the buff tinge to the head, and has a black tail. From a distance, or in poor visibility, albatrosses can be confused with northern gannets, particularly with immature plumage and more black on the wings.
Anatomical adaptations
Northern gannets have streamlined bodies adapted for plunge-diving at high speed; they lack external nostrils and their secondary nostrils can be closed when they are in water. The opening of their auditory canal is very small and is covered with feathers; the openings can also be closed in water using a system similar to that used for the nostrils. The sternum is strong and long, protectiing the internal organs from the water's impact. The lungs are highly developed and probably also play a role in reducing the effects of hitting water at high speeds and protecting the body from these effects. There are subcutaneous air sacs in the lower body and along the sides. Other air sacs are located between the sternum and the pectoral muscles and between the ribs and the intercostal muscles. These sacs are connected to the lungs and are filled with air when the bird breathes in. The air can be expelled by muscle contractions.
The feathers are waterproof, which allows the birds to spend long periods in water. A water-impermeable secretion produced by a sebaceous gland covers the feathers and the birds spread it across their body using their beak or their head. Individuals have a subcutaneous fat layer, dense down and tightly overlapping feathers that help them withstand low temperatures. A reduced blood flow in the webbing on their feet outside of the breeding season also helps to maintain body temperature when they swim.
Call
The northern gannet is a loud vocal bird, particularly in the colony. Its typical call is a harsh arrah-arrah or urrah-urrah, which is emitted upon arriving or when challenging other gannets at the colony. The call is shortened to a rah rah when fishing or collecting nesting material, and lengthened to a ooo-ah when taking off. The calls of the sexes are similar. According to the ornithologist Bryan Nelson northern gannets can recognize the call of their breeding partner, chicks and birds in neighbouring nests. Individuals from outside this sphere are treated with more aggression.
Distribution and habitat
Their breeding range is the North Atlantic on coasts influenced by the Gulf Stream, the exception being the colonies of the Gulf of Saint Lawrence and the islands off the east coast of Canada. They normally nest in large colonies, on cliffs overlooking the ocean or on small rocky islands. The waters near these cliffs have a summer temperature at the surface of between 10 and 15 °C (50 and 59 °F). The water temperature determines the distribution of Atlantic mackerel and herring, which are the main food source for the northern gannet. These areas also overlie the continental shelf. Northern gannet colonies can be found in the far north in regions that are very cold and stormy. The ornithologist Dr Bryan Nelson has suggested that they can survive in these regions due to a number of factors including: the combination of body weight and a strong beak that allows them to capture strong muscly fish and the ability to dive to great depths and capture prey far from the cliffs. Their fat reserves act as weight when diving and as food reserves during extended periods without food.
The northern limit of their breeding area depends on the presence of waters that are free of sea ice during the breeding season. Therefore, while Greenland and Spitsbergen offer suitable breeding sites, the arctic regions have summers that are too short to allow the northern gannets to lay their eggs and raise a brood, which requires between 26 and 30 weeks. The southern limit of their distribution mainly depends on the presence of sufficient prey.
Breeding colonies
Some breeding colonies have been recorded as being located in the same place for hundreds of years. The cliffs containing the colonies appear to be covered in snow when seen from a distance, due to the number of nests present on them. There is a written record of a colony on the island of Lundy from 1274. It noted that the population was declining due to hunting and the theft of eggs. The colony finally disappeared in 1909. 68% of the world population breeds around the coasts of the British Isles. Notable colonies include:
- Bass Rock, off the Firth of Forth in Scotland, first recorded in 1448. In 2004, it contained more than 48,000 nests. By 2014 this had increased to over 75,000, making it the largest colony in the world.
- Northern gannets began a colony at Troup Head in Aberdeenshire in 1988. By 2014 there were an estimated 6,456 pairs there.
- Saint Kilda and Sula Sgeir, in the Hebrides, Scotland. The former colony was estimated at 60,290 pairs and the latter 11,230 pairs in 2013. A colony on the Flannan Isles almost doubled in size to 5,280 pairs in 2013. Further south, the island of Ailsa Craig in the Firth of Clyde hosted an estimated 33,226 pairs in 2014. Ailsa Craig was known as a colony since 1583.
- On Shetland, there were an estimated 25,580 breeding pairs at Hermaness, 11,786 at Noss, and 3,591 at Fair Isle in 2013, while Orkney had and estimated 4,550 pairs at Sule Stack. Sule Skerry's breeding population rose from 57 to 1,870 pairs between 2003 and 2013.
- Grassholm off the Pembrokeshire coast in Wales had an estimated 36,011 pairs in 2015. Gannets began nesting here between 1820 and 1860, though never in great numbers, only exceeding 300 pairs by 1913.
- Bempton Cliffs hosted an estimated 12,494 pairs in 2015, more than tripling in size in 12 years.
- Little Skellig, a small island located about 12 kilometres (7.5 mi) off the Iveragh Peninsula is the largest colony in Ireland, hosting around 30,000 breeding pairs. Known as a gannetry before 1700, the colony was exploited by local people and dwindled to 30 pairs by 1880 before rapidly increasing again. There are small colonies on Ireland's southern coast.
- Eldey, a small island located about 16 kilometres (9.9 mi) off the coast of the Reykjanesskagi Peninsula, Iceland, hosting around 15,000 breeding pairs. Iceland has several small colonies along its coast, and on Grimsey, around 40 km north.
- Around 7500 pairs nest on two islets--Ortac and Les Etacs--off the coast of Alderney in the English Channel, with the first birds only nesting there in the 1940s. These birds migrate further south to the Mediterranean and west coast of Africa than more northerly breeding colonies. Nearby, the French island of Rouzic in the Jentilez archipelago off the coast of Brittany hosts the southernmost breeding colony of northern gannets. Established in the late 1930s, it had grown to over 11500 breeding pairs by 1995.
- Syltefjord in northern Norway is the northernmost colony, at 70°N--north of the Arctic Circle. There are three other colonies along the Norwegian coast, and all are on low islands.
In North America, there are six breeding colonies along the coast of Canada. The Gulf of Saint Lawrence hosts three colonies--Bonaventure Island, Bird Rocks and Anticosti Island--and there are three off the eastern and southeastern coast of Newfoundland (Cape St. Mary's Ecological Reserve, Funk Island, Baccalieu Island Ecological Reserve. Bonaventure Island off the south coast of Quebec is the largest colony with 32,000 nests.
Migration
After the breeding season the adults spread out over a wide area although they travel no more than 800 to 1,600 km (500 to 1,000 mi) from the breeding colony. It is not known if all birds from one colony migrate to the same over-wintering area. Many adults migrate to the west of the Mediterranean, passing over the Strait of Gibraltar and flying over land as little as possible. Other birds follow Africa's Atlantic coastline to arrive in the Gulf of Guinea. Immature northern gannets from colonies in Canada fly to the Gulf of Mexico while the adults do not fly that far.
The young birds migrate southwards for great distances and have even been recorded as far south as Ecuador. In their second year a number of birds return to the colony they were born in, where they arrive after the mature birds, they will then migrate south again at the end of the breeding season. They travel shorter distances in this second migration.
The species has been recorded as vagrant in many central and eastern European countries as far south and west as the Black Sea, and also in Bermuda, Cuba, Cyprus, Egypt, Kazakhstan, Svalbard, Jan Mayen and Syria.
Behaviour
The wings of the northern gannet are long and narrow and are positioned towards the front of the body, allowing efficient use of air currents when flying. Even in calm weather they can attain velocities of between 55 and 65 km/h (34 and 40 mph) even though their flying muscles are not highly developed: in other birds flying muscles make up around 20% of total weight, while in northern gannets the flying muscles are less than 13%. Despite their speed, they cannot manoeuvre in flight as well as other seabirds. Northern gannets need to warm up before flying. They also walk with difficulty and this means that they have difficulty taking off from a flat area. They take off from water by facing into the wind and strongly beating their wings. In light winds and high waves they are sometimes unable to take off and they can become beached. They take advantage of the wind produced by the front of a wave in the same way as the albatross does. They are only seen inland when they have been blown off-course by storms.
They alight on water with their feet retracted. They rarely land on water with their feet stretched forward like pelicans or cormorants. When they are on the water their body is rather low in the water with their tail pointing diagonally upwards. They alight with difficulty on land and often with a bump as their narrow wings do not allow them to turn easily and they have to use their feet and tail to aid in these manoeuvres. Individuals often suffer damage to their legs or feet when they land on the ground if there is not sufficient wind. Damaged or broken wings are a frequent cause of death in adults. The position of the legs towards the rear of the body means that they walk in a similar way to ducks.
Feeding
Northern gannets forage for food during the day, generally by diving at high speed into the sea. They search for food both near to their nesting sites but also further out to sea. Birds that are feeding young have been recorded searching for food up to 320 km (200 mi) from their nest. It has been found that 2% of birds nesting in the colony on Bass Rock search for fish at Dogger Bank, between 280 and 320 km (170 and 200 mi) away. It is likely that they fly greater distances than this while searching for food, possibly up to double this distance; however, they normally fly less than 150 km (93 mi). Some studies have found that the duration and direction of flights made while foraging for food are similar for both sexes. However, there are significant differences in the search behaviour of males and females. Female northern gannets are not only more selective than males in choosing a search area: they also make longer and deeper dives and spend more time floating on the surface than males. They will also follow fishing boats with the hope of finding food in the same way as gulls do. They fly around the boats to take fish from the fishing nets or pick up the remains thrown into the sea. They can locate their prey from heights of up to 45 m (148 ft), but they normally search from a height of between 10 and 20 m (33 and 66 ft). When they see a fish they will dive into the water. They dive with their bodies straight and rigid, wings tucked close to the body but reaching back, extending beyond the tail, before piercing the water like an arrow. They control the direction of the dive using their wings. A bird will fold its wings against its body just before impact, with its head and neck stretched out and beak shut. Birds can hit the water at speeds of up to 100 km/h (62 mph). This allows them to penetrate 3-5 m (10-16 ft) below the surface, and occasionally they will swim down to 12-15 m (40-50 ft).
They usually push their prey deeper into the water and capture it as they return to the surface. When a dive is successful, gannets swallow the fish underwater before surfacing, and never fly with the fish in their bill. Larger fish are swallowed headfirst, smaller fish are swallowed sideways or tail first. The bird's subcutaneous air sacs aid their rapid return to the surface. The fish is stored in a branched bag in the throat and does not cause drag when in flight. Their white colour helps other gannets to identify one of their kind and they can deduce the presence of a shoal of fish by this diving behaviour; this in turn facilitates group foraging, which makes capturing their prey easier. The colour also makes the gannet less visible to the fish underneath. Northern gannets also forage for fish while swimming with their head under water.
They eat mainly fish 2.5-30.5 cm (1-12 in) in length which shoal near the surface. Virtually any small fish (roughly 80-90% of their diet) or other small pelagic species (largely squid) will be taken opportunistically. Sardines, anchovies, haddock, smelt, Atlantic cod and other shoal-forming species are eaten. In the case of the larger fish species northern gannets will only eat the young fish.
Breeding
The oldest birds are the first to return to the breeding colonies. The exact duration of the breeding season depends on the colony's geographic location: the breeding season on Bass Rock starts in the middle of January, that of Iceland at the end of March or in April. The birds that are not of breeding age arrive a few weeks later. In general, birds first return to a colony (not uncommonly the one they were born in) when they are two or three years old. Once an individual has successfully bred in a colony it will not generally change to another.
Immature birds stay on the edges of the colony. They may even make a nest but they will not breed until they are four or five years old. Some birds of this age will occupy empty nests that they will aggressively defend if they have sat on them for two or three days. If an apparently empty nest has an owner the immature bird will leave without putting up a struggle when the owner arrives to claim it.
The preferred nesting sites are on coastal hillsides or cliffs. If these sites are not available northern gannets will nest in groups on islands or flat surfaces. As they find it more difficult to take off from these locations they will often cross the area occupied by an adjacent nest causing an aggressive reaction from the pair occupying that nest; this means that the stress levels are higher in this type of colony than in those on more vertical surfaces. Notwithstanding this, nests are always built close together and ideal nesting sites will not be used if they are some distance from a colony. On average there are 2.3 nests per square metre.
Nests are made from seaweed, plants, earth and all types of object that float on the sea. The males usually collect the materials. Nests measure between 50 and 70 cm (20 and 28 in) in diameter and are some 30 cm (12 in) in height; during the course of a breeding season they will sustain damage from the wind and other causes and they require frequent maintenance. The area which a nest occupies grows throughout the breeding season as the breeding pairs throw their excrement outside the nest.
Northern gannets exhibit many types of aggressive behaviour while they are nesting. Confrontations normally only take place between birds of the same sex. Females will lower their heads before an aggressive male that is defending its nest: this will expose the back of the female's neck and the male will take it in its beak and expel the female from the nest. A female will not react if a male approaches a nest but it will react fiercely if another female approaches. The fights between males that occupy nests for the first time are particularly intense. Such fights can lead to serious injuries. The fights are preceded by threatening gestures, which are also seen outside the breeding season. Males will demonstrate ownership of a nest by gesturing towards their neighbours with their head with the beak pointing down and the wings slightly outstretched.
Once males have found a place to breed they try to attract an available female. The females will fly over the colony a number of times before landing. Their posture, with the neck stretched out, tells the male that they are available for courtship. The male will then shake their heads in a similar way to when they are guarding their nest but with their wings closed.
Gannet pairs are monogamous and may remain together over several seasons, if not for all their lives. The pairs separate when their chicks leave the nest but they pair up again the following year. Should one of the pair die the other bird will leave the breeding ground and pair up with another single bird.
Both sexes fiercely defend the area around their nest. Where space allows, the distance between nests is double the reach of an individual.
Northern gannets only lay one egg that on average weighs 104.5 grams. This is lighter than for other seabirds. Where two eggs are found in a nest this is the result of two females laying an egg in the same nest or one of the eggs has been stolen from another nest. Northern gannets will lay another egg if the first one is lost. Incubation takes 42 to 46 days. During incubation the egg is surrounded by the brooding bird's webbed feet that are flooded with warming blood. The process of breaking the eggshell can take up to 36 hours. When this is about to take place the brooding bird will release the egg from its webbed feet to prevent the egg from breaking under the adult's weight as the chick breaks it open. This is a frequent cause of death for chicks of birds that are breeding for the first time. The webbed feet are also used to cover the chicks, which are only rarely left alone by their parents. Chicks that are left unattended are often attacked and killed by other northern gannets.
Newborn chicks are featherless and are dark blue or black in colour. In the second week of life they are covered in white down. From the fifth week they are covered in dark brown feathers flecked with white.
Young chicks are fed regurgitated semi-digested fish by their parents, who open their mouths widely for their young to fetch the food from the back of their throats. Older chicks receive whole fish. Unlike the chicks of other species, northern gannet chicks do not move about the nest or flap their wings to ask for food: this reduces the likelihood that they will fall from the nest.
The adults feed their offspring for around 13 weeks, being fed right up until the time they leave. The young birds fledge between 84 and 97 days old, departing by launching themselves off a cliff and flying--a procedure for which it is impossible to practice beforehand. If they leave the nest in bad weather they can be mortally wounded as they can be blown against the rocks. The young birds are attacked by adults if they enter the breeding ground, so they stay at sea learning to fish and fly. A high proportion of the young birds can die if storms occur at this time.
Northern gannets have only one brood a year. The survival annual rates for adults is 91.9%, and for young birds in their first four years it is 30%. The average lifespan is 17 years, and the maximum known age is 37 years 4 months 16 days.
Predators and parasites
This species is not heavily predated. The only known habitual natural predators of adults are bald eagles and white-tailed eagles. Predators of eggs and nestlings include the great black-backed gull and American herring gull, common ravens, ermine, and red fox. Predation at sea is insignificant though large sharks and seals may rarely snatch a gannet out at sea.
Kleptoparasitism by skuas, particularly the great skua, occurs at breeding sites. The skua chases its victim until it disgorges its stomach contents, providing a meal for the attacker. Skuas may catch the tip of the gannet's wing, causing it to fall into the sea, or seize the tail to tip it into the water. The gannet is only released when it has regurgitated its catch.
External parasites include feather lice, although there are relatively few species and none are found on the head. As with grebes and divers it may be that the short head feathers provide insufficient cover for the parasite. In one species, Michaelichus bassani, immature lice are found in the membranes lining the subcutaneous air-cells. Ixodes mites include the widespread I. uriae.
The spiny-headed worm Corynosoma tunitae appears to occur only in gannets and closely related seabird families such as the cormorants. The tapeworm Tetrabothrius bassani adsorbs toxic heavy metals at a higher concentration than the gannet's own tissues, with an average 12 times as much cadmium as the gannet's pectoral muscles and 7-10 times the lead level of the bird's kidney and liver. Since levels of these toxic levels are detectable in the parasite earlier than in the host, the tapeworm might be used as an early indicator of marine pollution.
Conservation status
A 2004 survey counted 45 breeding colonies and some 361 000 nests. The population is apparently growing between 3% and 5% a year, although this growth is concentrated in just a few colonies. 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 for their meat and feathers. In 1939, there were 22 colonies and some 83 000 nests, which means that the populations have increased fourfold since that time.
In 1992, the International Union for the Conservation of Nature (IUCN) estimated the bird's population to be some 526 000. However, taking into account an estimate produced for BirdLife International in 2004 of the European population, the IUCN revised its global population to between 950 000 and 1 200 000 individuals.
The IUCN lists northern gannets as a species of least concern, as they are widely distributed and as there is a large population that appears to be growing.
In culture
An early reference to the gannet is in the seventh-century Old English epic poem The Seafarer.
There I heard naught but seething sea,
Ice-cold wave, awhile a song of swan
Then came to charm me gannets' pother
And whimbrels trills for laughter of men,
Kittiwake singing instead of mead.
Gannets have long been eaten for food. Birds, mainly the young, were taken from Bass Rock for at least 350 years until 1885, when the annual cull of about 1500 individuals finally ceased, and Shetland gannets were sold as "Highland goose" in London restaurants during World War II. Views of the palatability of this bird are mixed, but as well as being a food for the poor it also regularly featured in Scottish royal banquets.
The best-known site was the remote island of Saint Kilda, where adults and eggs were taken in the spring. The fat chicks, known locally as "gugas", were harvested from the precipitous cliffs in August, just before they could fly, and thrown to waiting boats far below. Much of the meat was salted in barrels for storage, but the rest of the bird was also used. Islanders paid their rent in feathers for stuffing pillows and furniture, the stomachs were used to hold gannet oil, and the breastbones as lamp wicks.
Hunting on St Kilda ceased in 1910, but the gannetry on Sula Sgeir is still exploited under a licence that permits 2200 chicks to be taken each year. During the hunt, ten men live on the island, and the cleaned birds are singed on a fire fuelled by their own oil-rich offal. The filleted birds are then taken to Stornoway, where each hunter receives 200 skins to give away or sell. The name "Sula Sgeir" itself derives from sula, "gannet", and Old Norse skerr, a skerry. Other sites that continued hunting into the twentieth century were Eldey in Iceland, where the activity ceased in 1939, and Mykines in the Faroe Islands, where small-scale culling still persists.
Although the Bass Rock population fell to fewer than 4,000 pairs in the early nineteenth century, the population soon recovered once hunting ceased, and St Kilda was harvested sustainably for hundreds of years. Elsewhere, the recovery was less complete. The Bird Rock colony in the Gulf of St Lawrence may once have held 250,000 birds, but unchecked hunting, including for fish bait meant that the population was only 1,000 birds by 1932, despite government protection since 1904.
References
Notes
Bibliography
- Attenborough, David (1998). The Life of Birds. British Broadcasting Corporation. ISBN 978-0-563-38792-3.
- Bale, Peter (1982). Wildlife Through the Camera. British Broadcasting Corporation. ISBN 978-0-563-20069-7.
- Cocker, Mark; Mabey, Richard (2005). Birds Britannica. London: Chatto & Windus. ISBN 0-7011-6907-9.
- Cocker, Mark (2013). Birds and People. London: Jonathan Cape. ISBN 978-0-224-08174-0.
- Cramp, Stanley; Simmons, K.E.L. (1977). Handbook of the Birds of Europe, the Middle East, and North Africa: The Birds of the Western Palearctic. ISBN 978-0-19-857358-6.
- Gessner, Conrad (1560). Icones avivm omnivm (in Latin). Zurich: Excvudebat C. Froschovervus.
- Harrison, Peter (2003). Seabirds of the world, Sula bassana. Princeton, New Jersey: Princeton University Press. ISBN 978-0-691-01551-4.
- del Hoyo, J.; et al. (2004). Birds in Europe: population estimates, trends and conservation status. BirdLife International. ISBN 978-0-946888-53-5.
- del Hoyo, J.; Elliot, A.; Sargatal, J., eds. (1992). "Band 1 (Ostrich to Ducks)". Handbook of the Birds of the World. Barcelona: Lynx Edicions. ISBN 978-84-87334-10-8.
- Lockwood, W. B. (1993). The Oxford Dictionary of British Bird Names. Oxford University Press. ISBN 978-0-19-866196-2.
- Nelson, J. Bryan (2010) [1978]. The Gannet. London: A&C Black. ISBN 978-1-4081-3857-1.
- Nelson, J. Bryan (2005). Pelicans, Cormorants and their relatives. Oxford University Press. ISBN 978-0-19-857727-0.
- Reinsch, Hans Heinrich (1969). Der Basstölpel, Sula bassana (Linné 1758) (in German). Wittenberg: Ziemsen Verlag.
- Rothschild, Miriam; Clay, Theresa (1957). Fleas, Flukes and Cuckoos. A study of bird parasites. New York: Macmillan.
- Vieillot, Louis Jean Pierre (1816). Analyse d'une nouvelle ornithologie élémentaire (in French). Paris: Déterville.
- Weaver, Peter (2010) [1981]. The Birdwatcher's Dictionary. London: Bloomsbury Publishing. ISBN 978-1-4081-3852-6.
- Willughby, Francis (1681). The Ornithology of Francis Willughby of Middleton in the County of Warwick, esq. ... :. London, United Kingdom: A.C. for John Martyn.
External links
- Live camera from Eldey, Iceland
- "Northern gannet media". Internet Bird Collection.
- Northern gannet photo gallery at VIREO (Drexel University)
- Northern Gannet Stamps at bird-stamps.org
- BirdLife species factsheet for Morus bassanus
- "Morus bassanus". Avibase.
- Audio recordings of Northern gannet on Xeno-canto.
Source of the article : Wikipedia
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