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Seabirds

number of species worldwide:

more than 300

number of species in North Sea

around 30

largest North Sea bird species:

gannet, wingspan: 2 meters

smallest North Sea bird species:

petrel, wingspan 40 centimeters

enemies:

humans (competition with fisheries, hunting, pollution), raptors and disease and occasionally a seal

food:

fish, crustaceans, zooplankton, shellfish, young birds

  • Dut: zeevogels
  • Eng: seabirds, marine birds
  • Fre: oiseaux de mer
  • Ger: Meeresvögel, Seevögel
  • Dan: havfugle
Gannet, Marijke de Boer

Seabirds

Whoever stands on the beach and looks out to sea usually sees birds. Herring gulls in particular are easily recognized by everyone. Nevertheless, they are more of a coastal bird than a seabird. In general, one does not usually see true seabirds from land (unless they strand as oil victims, such as the gannets in Ecomare), yet only while at sea. The large group of birds which scavenge behind a fishing vessel for by-catch and fish wastes form a familiar picture.

  • Superstition
    Gannet, Marijke de Boer

    Seabirds have always made an impression in our imagination. Seamen from earlier days had little more than the seabirds which followed their ships as companionship during their long voyages. They considered their presence during windless weather a positive sign; it indicated that wind was on its way. They also believed that the souls of deceased seamen continued living in these seabirds
    With or without superstition, we observe seabirds with respect. They belong to the world of the sea in which people can only temporarily join with the help of artificial intervention. These birds feel at home at sea; that's where they spend a good part of the year and haul their food. They differ from the more coast-adapted tidal-flat bird in other aspects as well. Seabirds are regularly in the news as oil victims.

  • Bird species of the North Sea

    Around 300 species of seabirds are found in the oceans and seas throughout the world. Fulmars, gannets and auk species (the northern counterpart of the penguins) are found in the North Sea region. Kittiwakes and skuas are also spotted in the North Sea. Actually, all of these bird species only come on land to breed, especially on rocky coasts and cliffs. Therefore, one will not find them breeding in 'cliffless' countries such as the Netherlands.

  • Sea-worthy birds
    Fulmar, Foto Fitis, www.fotofitis.nl

    For warm-blooded animals such as birds, the marine environment is not an easy place to live. There is often no food available in the open sea and looking for protection during a storm and rain is out of the question. In order to protect themselves from these unfavourable conditions, seabirds possess a large food reserve in the form of fatty tissues and massive muscles. During times of poor food supplies, they can live off of their fat reserves for a short period of time. Besides food reserves in the form of fatty tissues and massive muscles, most seabirds have a large stomach. In this way, a fulmar can carry 20 % of its body weight in food. To keep warm and dry, the seabirds possess a perfect close-fitting plumage with a great water-resistant ability.
    Seabirds know how to use the salty seawater as drinking water. They can eliminate the salt from the seawater with the help of two glands situated on their scalp. Via a small canal, the excess salt is carried to the nostrils where it is excreted. One sometimes sees a highly concentrated drop of salt hanging on the tip of the beak.
    A number of seabirds have adapted to the relatively scarce amount of food on the open sea by only laying one egg and thereby only having to catch fish for one young. Even the long breeding period -usually over a month - and the slow growth of the young fits in: the chicks do not need much food per day. The young gannets are taken care of for at least three months before leaving the nest.
    Seabirds can grow to middle age. As opposed to most land birds (which are mature after just one year), seabirds are only mature on the average after five years.
    Seabirds are excellent flyers and/or swimmers. That means that their movements on land are often less skilful.

  • The art of hunting
    Puffin, Foto Fitis, www.fotofitis.nl

    Many seabirds eat fish. The birds have developed various hunting methods to catch their prey. Razorbills, guillemots and puffins dive deep under water. They not only resemble penguins externally, they also have the same manner of 'flying' under water, with half-open wings. They have webbed-feet which serve as a rudder. In this way, they can reach enormous depths. Guillemots have been spotted 180 meters deep. The gannet tracks its prey from the air and catches it by making its so-called jabbing dive: the animal dives from a height of 30 meters in a position perpendicular to the sea in order to seize its prey. With a speed close to 100 km per hour and wings folded back against its body, it cleaves through the water surface like a living torpedo. The enormous blow is absorbed by a strengthened skull and a protective air cushion under the skin. The fulmar is a typical surface hunter. While sitting on the water, it picks up fish waste or small fish and shrimp which swim just under the water surface.
    Many birds have white or grey bellies. This color serves as a hunting camouflage. When the birds swim on the surface or fly just above, the fish have a difficult time distinguishing them from the glittering water surface.
    One exception is the common scoter. Found in open sea west of the Dutch coast, this bird eats shellfish and therefore has no need of camouflage.

  • Distribution in the North Sea
    Guillimots, Marco Witte
    Guillimots, Marco Witte

    Due to the difficult accessibility and the extensiveness of the North Sea, it is not easy to determine the distribution of seabirds in this area. Nevertheless some facts have been established, for example during bird counts on board research vessels.
    The breeding areas of seabird species are the easiest to map. That is logical since seabirds are forced to find solid ground for reproduction, where they are easy to observe. Guillemots, razorbills and kittiwakes prefer breeding places on steep rocky cliffs directly by the sea. Such places are found by the North Sea on the Orkney and Shetland Islands and the British north-east coast. The only other steep rocky cliffs in the area are on the German island Helgoland. One can find a colony there consisting mainly of guillemots and kittiwakes.
    Seabirds make exceptional demands on their nesting place. It is not that they prefer steep cliffs, but they want to be protected especially from four-footed predators (foxes, rats). Therefore, inaccessible rock islands are ideal. One finds the nesting sites for puffins and gannets on top of breeding rocks. The dominating winds allow for easier flight take-offs.

    Puffins breed in holes on top of cliffs in grassy spots between the rocks. Guillemots and razorbills lay their eggs on the lower lying rocky ridges:

    Razorbills prefer deeper ledges, while guillemots prefer narrower ridges. All three mentioned species eat the same species of fish, however guillemots catch the larger fish, while puffins catch the smaller ones.

  • Seabird migration

    After breeding season, some seabird species stay the entire year in the vicinity of their nesting area. Others move elsewhere due to the change in seasons and food supply. The distances can vary between short and long. Many gannets and puffins leave the North Sea area after their chicks leave the nest, around the end of July. In the following spring, the birds return to their nesting grounds. There are four species that stay the entire year in the North Sea: fulmar, kittiwake, guillemot and auk. They do not participate in long migrations, but they migrate within the North Sea region. The guillemot nests in the spring along the English and Scottish northern and eastern coast and a part of the population departs in August with its young chicks to the eastern of southern part of the North Sea. In the early spring, the birds return to their English and Scottish nesting rocks.
    The southern North Sea is particularly important for seabirds as foraging area in the winter. Especially the Frisian Front, an area north of the Wadden Islands, attracts many seabirds. The tidal currents are so weak here that nutrient-rich mud can settle to the bottom. Therefore, there are lots of benthic fauna, fish and seabirds
    There is not much seabird migration to see in general along the Dutch beaches. The birds fly along the coast, but too far away to observe easily. Only with stormy northwestern winds do they fly closer to the coast. This is when unusual seabird reports are made. During such conditions, warmly dressed bird watchers with telescopes can be found scanning the rough seas.

  • Top of the food chain
    Recycling of nutrients in the marine environment, Ecomare

    Of course, seabirds are not the only animals found in the North Sea region. An enormous variety of life is housed under the North Sea waves. At the base of life in the sea are the microscopically small plants, the phytoplankton. In addition to water and carbon dioxide, they also need sunlight and nutrients (nitrates, phosphates, etc) in order to grow. In the shallow North Sea, these ingredients are normally present in abundance. A lot of phytoplankton is therefore produced. This is consumed by the zooplankton, which are mostly small animals which drift around in the water together with phytoplankton.
    The zooplankton is eaten by all kinds of benthic animals and (young) fish, which in turn are eaten by larger fish. All of these fish eventually end up on the menu for marine mammals, people and seabirds.
    All the plants and animals in sea together form a kind of series of 'eat and be eaten', which one calls the food chain. Sea birds belong to the top of the pyramid: they eat mainly small fish such as sprat and lesser sandeel. Only the gannet eats larger types of fish, such as mackerel.
    From studies of kittiwakes in Alaska, it became clear how important it is that gull species eat well. The kittiwake population in this area has declined by 50% since the 1980s. At the same time, there was also a reduced availability of fatty fish species due to climate change. It appeared that a lack of sufficient fatty fish caused damaging brain development, whereby the young kittiwakes are probably too stupid to survive.

  • Hunting seabirds

    Seabirds are not only interesting for people to observe. For centuries, island inhabitants on both sides of the North Atlantic Ocean have been catching fulmars, gannets, puffins, auks and guillemots and gathering seabird eggs. During winter months, these people were sometimes cut off from the rest of the world. The eggs gathered in the summer and the caught birds were used for consumption. The island residents regulated their harvest in such a way that the seabird populations (which became their food supply) were not in danger.
    The great auk had a different story. This seabird of the northwestern Atlantic Ocean was slaughtered on a large scale in the 19th century to serve as food for the seal hunters and fishermen. The great auk had adapted so well to hunting underwater, that it was unable to fly, just like penguins. This made it extra vulnerable and the last specimen was killed in 1844.
    People still eat seabirds. On Iceland and the Faroa Islands, where seabirds used to be an essential source of food, the residents still eat puffins. The birds are caught with the help of nets on poles. This 'fleyging' happens on boats, or even more often, by standing on steep cliffs of the nesting colony. The birds are caught in the air when they fly close along the cliffs on the way to their nest.

  • Threatened by poisons

    The pollution of the seawater with all kinds of toxic materials is also a big threat for seabirds. Toxic materials are found in many variations: heavy metals, pesticides, PCBs, PAHs, UGILECs, etc. All of these harmful materials flow in from the rivers, through accidents, discharges and incineration at sea, and even via precipitation from the air. Via the links in the food chain, they are carried up the line to the seabirds, where the materials accumulate in their fatty tissue. In extreme situations, a seabird will eat into its own fat reserves: the poisons are released into the blood and thereby attack all kinds of the bird's life functions. Extra deaths of seabirds therefore occur during breeding season and the winter months, when the birds address their fat reserves. It is known that the hormone balance is disturbed by the pesticide DDT (and its degraded product DDE): the production of calcium decreases. Calcium is found in egg shells. Because of DDT, these shells are thinner and break more readily. In Florida, breeding pelicans sagged through their own eggs as a result of DDT pollution.
    It has been proven that PCBs disrupt the reproduction of birds and mammals. They are also harmful for the immunity system whereby the animals grow less resistant to infectious diseases. In the meantime, the amount of PCBs in the fatty tissue of some seabirds has grown to tens of thousand times higher than in the seawater itself. It has been shown experimentally that such figures are extremely harmful for the seabird's anti-bodies against parasites and other diseases.

  • Covered in oil

    Oil is the best known and one of the biggest threats for seabirds. Every year, many thousands of seabirds die from oil pollution in the Dutch section of the North Sea alone! Only a fraction of these victims can be saved in the coastal rehabilitation centers, such as Ecomare.

  • Seabirds and fisheries: friend.
    Fishing boat with gulls following behind, Foto Fitis, www.fotofitis.nl

    In earlier days, fishermen fished on the North Sea with small boats. Nowadays, hyper-modern fish factories are among the boats, which not only catch fish but also process, pack and freeze them immediately at sea. The fish are tracked using modern sonar apparatus. Large amounts of fish are brought on land by these industrial fisheries.
    Some seabirds have profited for a long time from the fact that larger fish species such as herring, mackerel and cod were being caught in massive numbers. Smaller fish were rid of their predators and the competition for their food was solved. Species such as lesser sandeel and sprat could increase in number. Fulmars, kittiwakes and guillemots in particular profited from the disturbed situation because they eat these smaller species: lesser sandeel during the nesting season and sprat in the winter. Partially thanks to the abundance of the available food, a number of seabird species were able to recover spectacularly towards the end of the last century from the reduced numbers at the end of the 19th century due to hunting and egg-stealing.
    Many seabirds profit from the fish wastes thrown overboard by the beam trawlers. Kittiwakes and fulmars in particular have no problem finding the fishing boats.

  • ... and enemy!

    Seabirds and marine mammals drown regularly in the nets of the standing rigging fisheries. By the Norwegian coast, it has been established that around 30,000 guillemots die in fish nets per year.
    In the 1980s, an end seemed in sight for the growth of the seabird population in the North Sea due to the arrival of the industrial fisheries. This sector catches small fish such as lesser sandeel and sprat, which is food for many of these birds. The catch is ground to fishmeal and used to feed livestock, in fish farms, in cans and dry-food for cats and dogs and even as fertilizer. Before 1950, this form of fisheries on the North Sea was more or less unknown, but grew in the 1970s to a yield of two million tons of fish per year (compared to one million ton of fish for human consumption). Lots of industrial fish come from Danish and Norwegian fishermen, which make frequent use of giant ring nets in the North Sea. In addition to lesser sandeel and sprat, lots of young herring are caught.
    The first consequences of all that fishing are already apparent. On the Lofoten, a group of islands off the Norwegian coast situated at the very most northeastern part of the North Sea, only one out every thousands of parent pairs of puffins were able to bring up their young in the early 1990s. Lesser sandeel and young herring is food for juvenile puffins, and that had disappeared. The puffin population of the Lofoten grew old. Younger generations were lacking. Guillemots and kittiwakes found themselves in the same situation.
    Such problems also began elsewhere in the North Sea. After 1982, the lesser sandeel around the Shetland Islands declined in number. There were a lot of fishing activities taking place around this group of islands: from 1974 to 1982, the yields of lesser sandeel grew extremely rapidly from 8,000 to 52,000 tons per year. Since 1983, the Arctic terns in particular, but also the Arctic skuas, kittiwakes, puffins and fulmars had poorer nesting results due to the food shortage. In 1988 and 1989, the colonies of the great and Arctic skuas, the fulmar and the kittiwake did not produce even one young. The number of Arctic terns had declined by 70%.
    It cannot be proven from the above figures that the fisheries are the direct cause of the problem. It is possible that the problems by the Lofoten and Shetland Islands was caused by a change in the current pattern of the water. Changes in the direction of the current, salinity or temperature can have a major influence on fish stock. However, one can set major question marks as to why the situation deteriorated so badly for the seabirds.
    There are even more signals in which it appears that the birds in the North Sea have problems finding sufficient food during the nesting season as well as in the winter. The numbers of dead guillemots, auks and kittiwakes which washed ashore increased in the Netherlands during the winters in the 1980s, partially due to starvation, partially due to chronic (oil) pollution and partially because more birds overwinter in the southern North Sea. There seemed to be a slight improvement during the 1990s, as far as oil victims were concerned.

  • Lobbying for seabirds

    A number of environmental groups, such as Greenpeace, North Sea Foundation and the Wadden Sea Society, have been concerned about the future of seabirds in and around the North Sea. The Society National Committee Seabirds Oil-free - a joint program between the Dutch Bird Society, the Dutch Society for the Protection of Animals and coastal animal kennels, supports bird sanctuaries with funding for good accomodation and food during disasters involving birds. These groups attempt to educate politicians and public via campaigns and lobbying as to the deteriorating living situation for seabirds in the North Sea region.

  • Scientific seabird research

    There is not very much known about the distribution of seabirds around the North Sea, their choice of food and the best way to protect them. Observations during sea expeditions from people counting birds must supply more clarity.
    The scientists are also looking at the effects of pollution in the North Sea environment. Such studies are very important because the governments of the North Sea countries want to see proof. Only then can something maybe change. The Dutch Workgroup for oil victims (a division of the Dutch Seabird Group) studies the effects of oil pollution on seabirds. This study makes use of data from oil victims counts, that have been taking place since the Second World War. Oil victims are also examined internally in the Netherlands and other countries around the North Sea. In this way, addition data is obtains, concerning the cause of death, body condition and the affect of oil and other materials on birds.