SEAGULLS, TERNS AND SKUAS
Kittiwakes and glaucous gulls are the main gulls nesting on Svalbard. You can also see ivory gulls and sabine gulls, but they are not as numerous. The ivory gull is one of the most beautiful birds on Svalbard, with chalk-white plumage, black legs and yellowish bill. This gull is usually found near sea ice, and is often seen near polar bears with fresh seal kills, where they eat of the blubber and scraps that are left behind. On rare occasions, especially in autumn, the Ross’s gull is also seen migrating along the north coast of Svalbard.
Arctic terns are real long-distance flyers. They can stay on Svalbard or other northern areas during the summer, and then migrate south to Antarctica for their winter «vacation». This is a distance of nearly 20,000 kilometers. Nearly 10,000 breeding pairs nest on Svalbard, usually in open colonies along the west and north coasts.
All four European species of skuas are present in Svalbard. The two most common species are arctic skua (parasitic jaeger) and great skua that nest relatively commonly on Spitsbergen. More rare is the smaller longtailed skua, which nests on the west coast. The powerful pomarine skuas don’t nest in Svalbard but are regularly seen on shore, especially on the east coast during migration.In summer big flocks of kittiwakes gather in front of the calving glaciers, where they find food in the melting ice. Copyright: Roy Mangersnes
Seagulls is a group of birds where most species are strictly connected to the sea, at least in parts of the season. They are usually categorized in the smaller and larger gulls. They are usually white and pale grey as adults, while the young birds are brownish until sexually matured 3-5 years old. Breeding gull species in Svalbard include glaucous gull (Larus hyperboreus), herring gull (Larus argentatus), lesser black-backed gull (Larus fuscus) and black-backed gull (Larus marinus) that all belong to the larger gulls while the black-legged kittiwake (Rissa tridactyla), ivory gull (Pagophila eburnea), sabine’s gull (Xema sabini) and common gull (Larus canus) belongs to the smaller gulls. Common black hooded gull and ross’s gull are more or less yearly visitors to the archipelago, but does not breed.
All seagulls breed in colonies, and the largest in Svalbard is a black-legged kittiwake colony in Disco bay, eastern Svalbard of 11 000 pairs and one at Hopen of about 46 000 pairs.
The black-legged kittiwake population in the North East Atlantic has decreased by as much as 60% between 1980 and 2010, and still continues to decrease. The reason is lack of food, but the reason for the food shortage is more uncertain. For this reason, the kittiwake is considered one of the most threatened bird species in Europe.
Herring and capelin are two extremely important fish species in the Barent’s sea eco system. Herring is feeding on young capelin and larvae, and those two species will therefore never be abundant at the same time. Black-legged kittiwakes (and other species) shifts diet between the two fish species regarding their abundance. However, scientific studies have shown that the breeding success for the black-legged kittiwakes are much higher in years when capelin is the main prey compared to years when they feed mainly on herring.
The black-legged kittiwake is together with its red-legged relative in the Pacific the only gull species with only three toes (4 is normal in birds).
Black-legged kittiwakes GPS tagged in Kongsfjorden, Svalbard travelled south of Bjørnøya (about 450km) one year and the year before almost to the east coast of Greenland to find food during the incubation period. During this long distance foraging trips, they were away from their nest for about 2-3 days before returning to their nest so that their partner could fly out to feed.
Geolocation logger experiments have shown that most of the black-legged kittiwakes in Svalbard, Bjørnøya, Northern Norway and North West Russia congregate in a relatively small area east of Svalbard each September to feed. These areas are famous for the high concentration of capelin. In October the birds start to disperse out in the North Atlantic waters.
Even though many claim that the seagull population has increased dramatically the last years, the opposite is actually true. For many of the areas that have been monitored over some time, there have been shown a strong reduction between 50-75% since 1975.
Black-legged kittiwakes on ice in Monacofjorden, Spitsbergen. Copyright: Roy Mangersnes
The sabine’s gull is the only European seagull with a forked tail. Most sabine’s gulls don’t return to their breeding grounds the first summer after they are born as is different behaviour to most seagulls. Where the young sabine’s gulls are at this time is still unknown.
Because of the special behaviour and unique look, the sabine’s gull is the only species in its genus – Xema.
Sabine’s gull on their breeding ground on Nordaustlandet. This is possibly the pretties gull in Svalbard. Copyright: Roy Mangersnes
Most of the ivory gulls in Svalbard breed in colonies on inaccessible old nunataks (mountain peaks protruding through the glacier) on the inland.
The ivory gulls in Svalbard have shown two clear migration patterns – one east to the Bering sea, and another route west to the seas in the Davis Strait west of Greenland. What drives the different migration patterns is still unknown, but it seems that the birds all the time are strongly linked to the driftice.
The ivory gull is among the least studied gull species in the world.
Ivory gulls are often found in the pack ice, north of the archipelago, close to polar bear kills. Copyright: Roy Mangersnes
Arctic tern is the champion of the longest migration route of all birds in the world. It breeds in the Arctic and winters in the drift ice zone in the Antarctic about 17000 km one way. The tern is known to live to about 25 years of age, and this makes it cover astonishing 850 000km only during migration!
The arctic tern is the animal species in the world that experience most daylight hours during a year.
Among many species, especially insects, nuptial gifts are common. This is gifts (often food) that the male present to the female to impress her, and to show her how strong he is and what a good hunter and provider he is. This behaviour is obvious in early summer, when one often observe the arctic tern fly over the colony in circles while carrying a small fish in its bill. After some time, it lands next to a female, and feed her. The reward is mating.
Arctic tern feeds its chick, making sure it is fit for the long journey south. Copyright: Roy Mangersnes
Skuas are fast flying birds, similar to the sea gulls. They migrate south for the winter, and they are widely distributed in all oceans of the world. They hunt their food mainly by stealing from other birds. In Svalbard, there are three breeding skuas – great skua (Stercorarius skua), arctic skua (Stercorarius parasitticus) and long-tailed skua (Stercoraius longicaudus). Additionally the pomarine skua (Stercorarius pomarinus) is quite common in the sea off Svalbard all summer, but doesn’t breed here.
While the arctic skuas on mainland Norway are believed to winter off the coast of West Africa, arctic skuas tagged with geolocation loggers in Kongsfjorden, Svalbard, were found to spend the winter off the east coast of South- and Central America.
Arctic skuas exist in a pale morph and a dark morph. The darker morph get relatively more common the further south in the distribution area. About 75% of all arctic skuas belongs to the dark morph in Southern Norway, while only a very few birds belongs to this morph in Svalbard.
As for many of the waders, the arctic skua will also play hurt if a potential predator approaches the nest.
The great skua is extremely aggressive near the nesting sites, and they will regularly physically hit any intruder with great force. People have fainted when hit by an attacking great skua. Even polar bears are easily scared away by an angry great skua.
The great skua is a relatively new species to Svalbard. The first confirmed breeding in Svalbard was on Bjørnøya in 1970. In Spitsbergen, the first breeding was recorded in 1976.
Even though the pomarine skua looks very similar to the arctic skua, genetic studies have shown that it is much more closely related to the great skua.
In Svalbard, there are no birds of prey. The great skuas, together with the glaucous gull have adapted the role of birds of prey in the Svalbard eco-system.
The pomarine skua has prolonged middle tail feathers used as sexual ornament in the male. When the mating is done, many birds bite these tail feathers off themselves. This suggests that long tail feathers in this species are very costly for the male to carry, and is purely a trick to impress females.
Arctic skua taking off from the tundra on west Spitsbergen. Copyright: Roy Mangersnes
Great skua pair on a small island in Kongsfjorden. Copyright: Roy Mangersnes