Kittiwake
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Kittiwake ( Rissa tridactyla ), magnificent dress of kittiwakes
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The kittiwake ( Rissa tridactyla ) is a species of the seagulls (Larinae). The species breeds on the rocky coasts and cliffs of the Holarctic seas , mostly at great heights on small ledges and ledges and shows numerous adaptations to these breeding sites. In Central Europe, the species only breeds on Heligoland and on the northern tip of Denmark . Of all western Palearctic gulls, it is the most closely tied to the open sea and only breeds on the coasts. In the Central European inland, the species usually only gets through hurricanes and is a rare guest there, especially in winter. The diet consists mainly of marine fish, planktonic molluscs and crustaceans , which are primarily preyed on by diving. In recent decades bycatch thrown overboard by fishermen has also played an increasingly important role in nutrition.
The kittiwake population has risen sharply, at least in Western and Northern Europe, since around 1900 and is considered safe.
description
Kittiwakes have a body length of 37–42 cm and a wingspan of 93–105 cm; they are therefore only slightly larger than a black-headed gull . In the splendid dress , the back and top of the wings are gray, the ends of the three outer hand wings are black without white tips. The head, trunk, lower wings and tail are pure white. The tail is only slightly forked or cut straight. The strikingly short legs are dark gray to black. The rear toe is almost completely reduced, the epithet tridactyla and the German name refer to it . The beak is a solid greenish yellow. The throat and eye ring are bright red, the iris is dark.
The sexes are colored the same, but males are on average slightly larger and heavier than females. J. Dwight gives a wing length of 295–322 mm for males , on average 305.1 mm, for females a wing length of 285-314 mm, on average 297.9 mm. Males measured on Spitzbergen had a wing length of 312–329 mm, with an average of 320.7 mm; Females from there a wing length of 301–306 mm, on average 304.3 mm. Males arriving in a colony in Great Britain in spring weighed an average of 390.3 g and females 350.7 g.
In the plain dress , the back of the head and the back of the neck are pale gray, this gray color is bordered to the front by a dark gray ear mark similar to that of the young birds, which runs narrowly from the top of the head downwards and extends to the front about under the eye. In addition, a diffuse gray band runs from the forehead to the eye. The throat is pale red-yellow, the eye ring is dark red or black.
The young birds show a wide, black zigzag band on the upper side of the wing, which starts at the umbrella feathers and runs diagonally forward to the wrist and from there to the tips of the outer hand wings . They also have a black neck band that extends to the front about to the side of the neck, a clear vertical ear mark and a smaller dark spot above the eye. Finally, they show a narrow black tail band. The tail is slightly forked; this crotch is visually enhanced by the fact that the tail end band is widest in the middle of the tail. The beak is black; the legs are mostly dark gray, occasionally pale grayish flesh-colored. The birds are colored by the age of three.
Kittiwakes are very agile fliers; active flight is often interrupted by gliding phases. Similar to petrels, these gulls use the updrafts over the waves. On land, however, the species is almost immobile and only walks a few steps.
Similar species
In Europe, the kittiwake is not to be confused with any other species of gull. The greatest resemblance is here most likely with the common gull , which is also yellow-billed in its splendid dress , but it is much larger and its legs are much longer and also yellowish-green. The kittiwake also differs from all other smaller seagulls by its short legs, the white, unmarked head and the yellow beak.
In juvenile dress, the species in Europe can be confused with the little gull, which regularly migrates and breeds in Eastern Europe, as well as the swallow gull and rose gull, which can only be observed exceptionally in Europe . The kittiwake differs from the Little Gull and Swallow Gull primarily in that it has a plain gray back, even when young. In contrast to the kittiwake in their youthful dress, the rose gull has no black neck band and overall less black on the head.
The only other species of the genus Rissa , which only occurs on the coasts of the North Pacific , the rock gull ( Rissa brevirostris ), has coral-red legs in contrast to the kittiwake in its splendid dress and also a dark gray upper side and a shorter and stronger beak. In its youthful dress the rock gull shows a less strong neck band, a pure white tail and pink legs.
Vocalizations
The courtship call often uttered in the colonies sounds something like "kiti-uääh" and has given the species its onomatopoeic English name "Kittiwake". The alarm call is a plaintive "ec ec". Outside the breeding season and in the open sea, kittiwakes are mostly mute; here only a deep voice- touch call is uttered more frequently, which is rendered as “ketch, ketch”.
distribution and habitat
The distribution area of the kittiwake includes the steep rocky coasts of the Holarctic from the high Arctic to the temperate zone during the breeding season . Only coastal areas that offer suitable breeding opportunities and an attractive food supply in the adjacent sea areas are colonized, so the colonization of the coasts is very patchy.
The British Isles, whose coasts are relatively densely populated, are home to the largest European population ; the species is also widespread on the coasts of the Faroe Islands and Iceland . In western continental Europe, the species occurs in a few places on the coasts of Galicia ( Spain ) and Portugal, as well as on the north-western coast of France . In Central Europe, the kittiwake only breeds on Helgoland and at Bulbjerg on the northern tip of Denmark . In northern and northeastern Europe, the species occurs at one point on the west coast of Sweden and from central Norway along the entire coast to the north and east to the eastern tip of the Kola Peninsula. To the east of it there are deposits in European Russia on the island of Waigatsch , on Novaya Zemlya and Franz Joseph Land . Further east, the species occurs only sporadically on the coasts of western and central Siberia ; The coasts of eastern Siberia from Wrangel Island and the mouth of the Kolyma to the east and south to the southern tip of Kamchatka and Sakhalin are then more densely populated.
In western North America, the occurrence is limited to the coasts of Alaska and the Aleutian Islands , in the east of the continent the species is sparsely distributed in the extreme north and east of Canada . The coasts of Greenland are relatively densely populated.
Outside of the breeding season, the kittiwake lives pelagic in the open sea .
hikes
Breeding birds leave the breeding grounds after the young birds have fledged around the end of July to mid-August, the young birds follow around a month later. Migratory movements take place in the northernmost populations in a north-south direction, but otherwise rather undirected depending on the food supply and weather. The regular wintering area includes the seas of the northern hemisphere, whereby birds from northern breeding colonies also seem to winter further north on average than birds from colonies located further south.
In the Pacific, the main wintering area extends to around 30 ° to 40 ° N; In the Atlantic, most of the birds overwinter from the pack ice zone to the Sargasso Sea , to the Azores and further east to around 40 ° N. South of this line and in the western Mediterranean, only a few kittiwakes overwinter, most of which are young birds. The greatest concentrations of overwinterers in the Atlantic are found on the east coast of North America in the southwest of the Labrador Basin and in the shelf zone off Newfoundland and Nova Scotia .
Re-discoveries of ringed birds have shown that European birds regularly cross the Atlantic; conversely, ringed kittiwakes were also found several times in Europe in western Greenland, and in a single case a gull ringed in Germany in western Greenland. Kittiwakes prefer to stay in areas with moderate and constant wind or with increasing wind strength, but avoid low pressure areas and weather fronts. The number of birds in an area can therefore increase from under 100 to several thousand individuals and vice versa within a few days.
Some of the breeding colonies in the temperate zone are visited again in January and further north from March and April.
Occurrence in Central Europe
Kittiwakes can be found all year round as breeding birds in the North Sea (see above), and there are also over-summerers and numerous winter guests. For example, in the Dutch part of the North Sea, 15,000–45,000 individuals spend the summer, in autumn (October and November) up to 150,000 individuals are present and the winter population is between 100,000 and 150,000 individuals. On the coasts of the Netherlands it is only observed in small numbers under normal weather conditions, but especially during autumn storms over 5000 and a maximum of 10,000 migrating individuals can be observed on the coast on individual days.
In the Baltic Sea and in the central European inland, both young and adult birds are rarely observed, but mostly every year and every month. These are evidently migrating or undirected young birds that have migrated from the place of birth and, in the case of adult birds, primarily roaming non-breeders. Larger numbers are usually only shipped there after storms from western directions, especially in January and February. Many of these birds are then found severely weakened or dead. Almost without exception, evidence in inland areas is carried out on larger bodies of water.
On the Baltic coast of Mecklenburg-Western Pomerania , usually up to 10 individuals are observed annually, most of them west of Rügen . Between 1954 and 1984, 200 individuals were found on the coast without considering the year of entry, 1983, and another 22 inland. In addition to weaker storm-related flights in 1962 and 1977, it came as a result of a hurricane on 18/19. January 1983 the strongest entry of at least 710 individuals, 173 of them inland. 327 records, i.e. around 43%, were found dead.
In Brandenburg and Berlin , as in the interior of Mecklenburg-Western Pomerania, the species is a rare but almost annual guest. From 1959 to 1977 a total of 58 individuals and from 1978 to 1998 68 individuals were observed here, i.e. about 3 individuals per year. Evidence is available from all months, but the occurrence here shows two clear peaks in January / February and from August to November. Here, too, the effects of the January orca from 1983 were still clearly noticeable, as a result of which 17 individuals were observed here.
In Switzerland , which is still further away from the coast , the evidence concentrates on the period from September to May; 317 individuals were found here between 1950 and 1996. Stronger inflows took place here in 1955, 1957, also in 1983 and 1993.
nutrition
The kittiwake feeds primarily on small marine fish, planktonic molluscs and crustaceans . Insects , poly-bristles and echinoderms are also used to a very limited extent . The most common hunting method is thrust diving from a 10 to 25 m high search flight, the seagull dipping a maximum of 0.5–1.0 m; occasionally, kittiwakes dive right in while swimming. In addition, prey is caught from the surface of the water while flying over it or when landing briefly on the surface of the water. Furthermore, kittiwakes often fly behind fishing trawlers and use the bycatch thrown overboard , but also kitchen waste or bread. Especially with food shortages parasitize kittiwakes other seabirds, there are next to other dogs, especially alkene , but also skuas attacked.
Reproduction
Courtship and nest building
The kittiwake breeds in colonies on cliffs and rock walls, but occasionally also on buildings near the coast. The colonies can contain a few, but also 30,000–40,000 breeding pairs, up to a maximum of 100,000 breeding pairs. The onset of sexual maturity is unknown. Birds first visiting a British colony were 2 to 7 years old; first broods took place at the age of 3 to 8 years, mostly at 4 to 5 years. The kittiwake leads a monogamous seasonal marriage, often breeding again with the previous year's partner; Up to 11 years of partner loyalty is proven.
The nest is usually located on narrow ledges, ribbons, cracks in the rock and similar structures, on buildings also on projections, window sills or on roofs. Only the nest location is defended as a "territory", a minimum area of around 0.8 m², so that the maximum nest density is around 12 nests per 10 m².
Conflicts with conspecifics are mostly limited to turning the head with the beak slightly open, with increased aggression the beak is torn open further, the red throat demonstrated and the wings spread apart. Conflicts with physical contact are rare, the opponents try to grab each other by the beak and then turn the opponent's head back and forth until he has to leave the ledge.
Unmated males advertise on the nest with nest curls. The neck is curved in an S-shape and the beak is held down. The male then calls "ae, ae, ae" and opens its beak more and more. Females landing on the nest are greeted with courtship calls and often with repeated nest lures. The females are very anxious at the beginning and the males often peck at them, but with increasing attunement this aggressive behavior subsides more and more. Females willing to mate sit on the nest, pull their heads back and make nodding movements. They then often snuggle up to the male and beg for food by pecking their beak, whereupon the male responds with a nod of the head and chokes up food, which the female then takes from the throat. After that, copulation usually takes place. In well-rehearsed pairs, mating takes place without prior courtship.
Nest building often begins at the end of February. The nest is built from earth, mud and parts of plants. The nest material is thrown over the shoulder onto the nest and then trampled with the feet and formed into an edge wall by pushing with the chest. The nests are often used several times, the height of these nests can therefore be 15 to 80 cm and the diameter is at least 20-25 cm.
Clutch and rearing of young birds
Depending on the area of distribution, eggs are laid at the earliest at the beginning of May and at the latest in mid-June; the main laying time varies accordingly between mid-May to mid-June and the end of June. The clutch consists of one to three, usually two eggs , the laying interval is about 2.7 days. The eggs, which are relatively sharply pointed on one side, measure around 56 × 40 mm on average and weigh around 52 g on average. They are darkly spotted on a light gray to light brown background. Both partners brood, they peel off two or three times a day. The breeding season in a colony in Great Britain was 25 to 32 days, with an average of 27.3 days.
Chicks and adult birds show numerous adaptations to the special dangers of the breeding grounds. The chicks are in contrast to the chicks of gulls Genus Larus pronounced Nesthocker , they stand at the earliest at the age of 10 days and then only rarely long and never run. Also in contrast to Larus chicks, the kittiwake chicks do not have any camouflage coloring. They are white-gray, the front back, the sides of the neck and the flanks are often slightly yellowish.
As soon as the chicks have hatched, an adult bird always stands on the outer edge of the nest with its belly facing the wall in order to provide shade for the chicks and prevent them from falling. The young birds are fed with a food pulp in the crop , which they get directly from the throat of their parents. The chicks begin to flap their wings as early as the third day, but always do so with their head against the wall and never lift off the nest. The wing-flapping young bird also apparently uses a call to ensure that the other young birds lie quietly in the nest during this time.
After 25–34 days, the presence of the adult birds drops to around 30% of the day and then fades away completely by the time the young birds fled. The adult birds now stay near the nest and defend their young when threatened. After 34 to 36 days, the young birds can fly in an emergency, but normally they only fly out after 42 to 43 days. The young birds are still fed on the nest after they have fled the country.
In a British breeding colony, the mean individual breeding success varied considerably. First brooders had an average of 1.07 young birds / year, the maximum number of young birds had experienced birds that were true to their species and brooding in the density center of the colony with 1.62 young birds / year. On average, 56 young fledged from 100 eggs laid there. The breeding success also depends on the size of the colony; it is much lower in small colonies than in colonies with more than 200 breeding pairs. The colonies are normally inaccessible to ground predators and are only visited in exceptional cases by birds of prey , but small colonies in particular can experience significant losses from large gulls of the genus Larus and skuas .
Mortality and life expectancy
The mortality of young birds in a British colony was 21% in the first year of life and 14% in the following years. The mortality of the breeding birds was different depending on the sex. Females breeding in the colony for the first time had an annual survival rate of 86%, the males 81%; after the first brood, the life expectancy of the females was 7.1 years, that of the males 5.4 years. In the last few decades, hunting has only played a regional role as a cause of death, especially in Newfoundland and Greenland . The biggest cause of loss are storms. Kittiwakes sleep in the sea almost all year round and are therefore particularly at risk from oil spills.
A kittiwake found dead and ringed in Great Britain was 28 years and 6 months old.
Re-discoveries of 17 and 18 year old birds show that the potentially attainable age of the kittiwake, like that of other gull species, can be very high.
Systematics
In addition to the kittiwake, the genus Rissa contains only one other species, the rock gull ( Rissa brevirostris ). The Pacific kittiwake population is often identified as a separate R. t subspecies . pollicaris , Glutz von Blotzheim and Bauer do not recognize the subspecies. A molecular genetic investigation of the subspecies question is not yet available.
Existence and endangerment
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In the 19th century the kittiwake was persecuted to such an extent that many breeding colonies were abandoned and the existing ones fell sharply. The birds were shot for fun, the eggs and young birds were eaten. With the introduction of the first protective measures around 1900, the species increased again in Great Britain. A general increase in stocks could be observed at least in Western and Northern Europe from the mid-1930s at the latest, and this increase continued at least until the end of the 1980s. In the course of this population increase, Heligoland , where the species brooded until the beginning of the 19th century, was repopulated in 1938, Denmark in 1941 and Sweden in 1967. The main cause of this increase in population was, in addition to the extensive elimination of direct persecution, the increasing number from the mid-1950s on bycatch thrown overboard from the fishery, which is used intensively by kittiwakes. For example, in the 1990s this was the main food of the colony on Heligoland.
A reasonably complete survey was carried out on the British Isles for the first time in 1959; the population was estimated at 170,000 to 180,000 breeding pairs that year. In 1969/70 470,000 pairs were counted, and by the end of the 1980s the number had increased to 543,600 pairs.
On the Faroe Islands , the population was first fully recorded in 1987, when 230,000 pairs were counted. When counting again in 1997, a sharp decrease to only 160,000 pairs was found, which is mainly attributed to lack of food during the breeding season.
In the first decades after the repopulation in 1938, the population development on Heligoland was very restrained. By the end of the 1960s the population grew slowly to around 200 pairs, after which the number of breeding pairs increased very strongly and stabilized after 1995 at 7000–7500 pairs.
Norway's population was estimated at 510,000 pairs in the early 1970s and was still increasing at that time.
At the end of the 1980s, the world population was estimated at around 6.8 million pairs; in 2002, 17 to 18 million individuals were given, of which around 900,000 were on the east coast of North America. The population in the Pacific was given as 2.6 million individuals in 1994.
Despite declining populations at least in some areas, the species is classified by the IUCN as "Least Concern" due to the still very large world population .
literature
- Einhard Bezzel: Compendium of the birds of Central Europe. Nonpasseriformes - non-singing birds . Aula, Wiesbaden 1985, pp. 553-556, ISBN 3-89104-424-0 .
- Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbook of the birds of Central Europe . Volume 8 / I, Charadriiformes (3rd part) snipe, gull and alken birds. Aula, Wiesbaden 1999, ISBN 3-923527-00-4 .
- Lars Svensson , Peter J. Grant, Killian Mullarney and Dan Zetterström: The new cosmos bird guide. Kosmos, Stuttgart 1999, ISBN 3-440-07720-9 .
Web links
- Rissa tridactyla in the Red List of Threatened Species of the IUCN 2009. Posted by: BirdLife International, 2009. Accessed on March 11 of 2010.
- Videos, photos and sound recordings of Rissa tridactyla in the Internet Bird Collection
- Kittiwake feathers
supporting documents
Individual evidence
- ↑ J. Dwight: The gulls of the world; their plumages, moults, variations, relationships and distribution. In: Bulletin of the American Museum of Natural History . Volume 52, 1925, pp. 63-408, plates V-XV. Quoted in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, seagull and alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 150
- ↑ de Korte, Beaufortia 20, 1972. quoted in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, Möwen- and Alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 150
- ↑ JC Coulson: Competition for breeding sites causing segregation and reduced young production in colonial animals. In: PJ den Boer and GR Gradwell (eds.): Dynamics of populations. In: Proceedings of the Advanced Study Institute for Dynamics Number Population . Oosterbeek 1970, Wageningen 1971, pp. 257-268. Quoted in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, seagull and alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 150
- ↑ Fiedler, Wolfgang, Olaf Geiter Ulrich Köppen: Messages from the ringing centers, ornithological station, August 2012, p. 201
- ↑ RG Bilsma, F. Hustings and Kees (CJ) Camphuysen: Algemene en schaarse bird van Nederland . GMB Uitgeverij / KNNV Uitgeverij, Haarlem / Utrecht 2001, pp. 258-259, ISBN 90-74345-21-2
- ^ G. Klafs and J. Stübs (eds.): The bird world of Mecklenburgs. 3rd edition Aula, Wiesbaden 1987, p. 226, ISBN 3-89104-425-9
- ↑ T. Ryslavy: Kittiwake - Rissa tridactyla . In: Association of Berlin-Brandenburg Ornithologists (ABBO): The bird world of Brandenburg and Berlin . Natur & Text, Rangsdorf 2001, pp. 334–335, ISBN 3-9807627-5-0 .
- ^ R. Winkler: Avifauna of Switzerland. Der Ornithologische Beobachter, Supplement 10, 1999, pp. 114-115.
- ^ RD Wooler & JC Coulson: Factors affecting the age of first breeding of the Kittiwake . In: Ibis 119, 1977, pp. 339-349. Quoted in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, seagull and alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 162
- ^ JC Coulson and E. White: Observations on the breeding of the Kittiwake . In: Bird Study 5, 1958, pp. 74-83. Quoted in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, seagull and alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 167
- ^ JC Coulson: The significance of the pair-bond in the Kittiwake . In: Proceedings of the XV International Ornithological Congress, The Hague . EJ Brill, Leiden 1972, pp. 424–433 cited in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, Möwen- and Alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 167
- ↑ Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, seagull and alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 169
- ^ Fransson, T., Kolehmainen, T., Kroon, C., Jansson, L. & Wenninger, T. (2010) EURING list of longevity records for European birds , November 26, 2010.
- ↑ z. B. Alaska Natural Heritage Program: Kittiwake: p. 1 pdf, online
- ↑ Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes (3rd part) Schnepfen-, seagull and alkenvögel. 2nd edition, Aula, Wiesbaden 1999, p. 145
- ^ A b R. K. Berndt, B. Koop and B. Struwe-Juhl: Vogelwelt Schleswig-Holstein. Volume 5: Breeding Birds Atlas. 2nd edition, Karl Wachholtz, Neumünster 2003, p. 442, ISBN 3-529-07305-9
- ^ A b P. M. Walsh and ML Tasker: Kittiwake . In: D. Wingfield Gibbons, JB Reid and RA Chapman: The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991. Poyser, London 1993, pp. 212-213, ISBN 0-85661-075-5
- ↑ Bergur Olsen: The kittiwake in decline . Fiskirannsóknarstovan 2008 engl. Translation, online
- ^ JC Bartonek and DN Nettleship: Conservation of marine birds of northern North America. Pap. Int. Symposium Seattle, Washington 1975. United States Department of the Interior, Wildlife Research Report 11, 1979, 319 p. Cited in: Urs N. Glutz von Blotzheim and Kurt M. Bauer: Handbuch der Vögel Mitteleuropas , Volume 8 / I, Charadriiformes ( Part 3) Snipe, seagull and alken birds. 2nd edition, Aula, Wiesbaden 1999, p. 154
- ↑ Alaska Natural Heritage Program: Kittiwake: p. 2 pdf, online
