Atlantic shearwater
| Atlantic shearwater | ||||||||||
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Atlantic shearwater at the breeding site |
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| Scientific name | ||||||||||
| Puffinus puffinus | ||||||||||
| ( Brünnich , 1764) |
The manx shearwater ( Puffinus puffinus ) is a species of bird from the family of the Petrels (Procellariidae), whose breeding grounds are located on islands and coasts of the northern Atlantic. After the breeding season, the birds migrate to the southern Atlantic and hibernate in the open sea off the coast of Brazil and Argentina. The species nests in burrows, is nocturnal at the nesting sites and is noticeable for its creepy-looking, hoarse clawing and cackling noises. While one partner is incubating, the other partner undertakes feeding flights hundreds of kilometers, often up to two days. The food mainly consists of small schooling fish, but occasionally also small squids or crabs.
The Atlantic shearwater is one of a super species that was formerly known as the black-billed shearwater and whose eight subspecies are now viewed as separate species. The Atlantic Shearwater is very closely related to the Balearic Shearwater and the Mediterranean Shearwater . The species are very similar and sometimes difficult to distinguish.
description
With a length of 30–38 cm, a weight of 350 to 575 g and a wingspan of 75–89 cm, the Atlantic shearwater is about the same size as a black-headed gull . It is one of the medium-sized species of the genus. The iris is blackish. The dark brown-gray or blackish bill is quite long and narrow and often a little lighter at the base. Legs and feet are pink or bluish flesh-colored with a black-brown rear edge, outside toe and outside of the middle toe. The webbed feet are greyish. The sexes do not differ. The youth dress is similar to the adult annual dress, but is recognizable between September and December by its fresh condition.
The plumage of adults is quite contrasting with a dull slate-black upper side and a white lower side in the worn plumage. The transition is speckled gray and white on the head and neck sides, but in contrast to the similar Balearic Shearwater, it is very sharply defined - between the ear covers and the back of the neck some white bristle feathers form a sickle-shaped "incision". In the area of the rump, the transition is sharp with a white bulge behind the wings. The predominantly white lower wing shows a broad, dark gray hind wing edge, which is widest at the wing tip. The front edge is narrow dark gray. A few dark axillary feathers often form a band at the base of the wing.
The Atlantic shearwater, like other shearwater divers, usually glides with spread, motionless wings close above the surface, whereby he regularly tilts to one side or the other and almost touches the waves with his wing tips. The English name Shearwater also refers to this behavior . The top and bottom can be seen alternately.
voice
The vocal utterances of the Atlantic Shearwater can be heard almost exclusively at night at the breeding sites, but are made both in flight and from the ground or from the breeding caves. These are loud, rhythmic and throaty, cackling series of calls made up of four to five syllables that are repeated over and over and can be described as kitti-ku-ru , for example. The first syllables are emphasized and louder.
The first birds that arrive in the colonies from March onwards are mostly still silent. After about a week, the nocturnal call concerts set in and increase steadily until May. The voices of the sexes are clearly different, which is particularly noticeable in call duets. Males call more clearly, more rhythmically and higher up, females less clearly structured and more harsh. Presumably, females can individually distinguish the voices of their partners, which the other way round is not the case.
Loud whistling noises have been described of birds at sea, but these are apparently only very rarely heard.
distribution
The Atlantic shearwater inhabits islands and coasts of the North Atlantic and can be found in large parts of the northern and especially the southern Atlantic outside of the breeding season.
There are breeding occurrences on the Westman Islands off Iceland, the Faroe Islands , the Hebrides , Orkneys and Shetlands . The species also breeds abundantly on cliffs and islands on the coasts of Great Britain and Ireland. There are large colonies for example on rum in Scotland, Skokholm and Skomer in Wales and on the Isles of Scilly . In the area of Brittany , the islands of Bannec , Molène and Rouzic on the Sept Îles are or were populated. Further south, the Atlantic Shearwater breeds in the Azores , Madeira , the Ilhas Selvagens and the Ilhas Desertas as well as some Canary Islands ( Tenerife , La Palma , suspected breeding on La Gomera and El Hierro ).
In North America, the Atlantic shearwater occurs as a breeding bird on offshore islands in Newfoundland and Massachusetts . Until 1905 he also brooded in Bermuda .
Duration
The Atlantic shearwater is not endangered and is listed by the IUCN in the "least concern" category. The worldwide population was estimated at between 350,000 and 390,000 breeding pairs (BP) in 2004, which corresponds to a total population of between 1,050,000 and 1,170,000 individuals.
The British Isles alone account for 333,000 BP. They are distributed over 40 colonies, of which the three largest are on Skomer with 102,000 BP and Skokholm in Wales with 46,000 BP and on Rhum in Scotland with 120,000 BP. There are around 50 BP in the Channel Islands and 192 in France (1999). Iceland holds between 7,000 and 9,000 BP and the Faroe Islands around 15,000 BP. With over 500 BP the species occurs in Madeira, with over 200 in the Canary Islands. In 1999 the Azores ranged from 115 to 235 BP.
Overall, the population seems to be stable, especially in the north. In the north-western Atlantic, there were new settlements on the North American Atlantic coast from the 1970s. At the same time, the sightings in the northeastern Pacific increased. Breeding was suspected in British Columbia and Alaska . In the Azores and Canaries, the population trend seems to be declining.
Light pollution is one of the causes of danger ; street or festival lighting and fireworks attract the birds, blind them and then go to the ground. Also introduced soil enemies such as rats or house cats can have a strong impact on the population. The targeted extermination of the brown rat on the Welsh island of Grasholm led to a population increase from 849 BP (1993) to 3835 BP (2012) around the turn of the millennium.
In the past, the species was used intensively by humans as a source of food. In the Azores, shearwaters were caught in large quantities from January to April and cooked or cured and used for fattening pigs. The young were mainly caught to gain urine. Today, human use there is no longer a major risk, but 1000 to 5000 young are legally collected in the Faroe Islands every year.
hikes
Especially the northern populations of the Atlantic shearwater are long-distance transequatorial migrants, which - after the breeding season - initially move south in September and October and have reached the main wintering areas off the Atlantic coast of Brazil and Argentina within two to six weeks. These lie between 10 and 50 ° S, but most of the birds are concentrated between 20 and 40 ° S. The migratory routes most likely lead across the east of the Atlantic before the birds turn west.
The stay in the wintering areas extends for about four to five and a half months. The home migration begins between February and April and lasts between 22 and 58 days. It takes place a little further west than the arrival - east of the Lesser Antilles , Bermuda and the North American east coast. It can include several longer stays. Overall, the hikes run as a clockwise loop across the Atlantic.
The birds arrive in the breeding areas from March, although the spring migration can drag on until May. Immature non-breeders sometimes spend the summer in the mid-Atlantic off the east coast of the USA and even in the northern Caribbean.
Winterers can be found in very small numbers in many parts of the Atlantic and even reach far into the Pacific - passing Cape Horn . Here the evidence extends to the northeastern part (e.g. Washington , Oregon ). The species was discovered as a stray visitor in many European countries and flies long distances over land, as evidence in the Alpine countries or in Montana shows.
habitat
The Atlantic Shearwater is a sea bird that is mainly found in the area of the shelf . It breeds on coastal and offshore islands or headlands , where it mostly populates slightly hilly, grassy terrain. In the Canary Islands, the species is also found in laurel forests on cliffs. The breeding occurrences can be up to a kilometer or two inland. In the area of the fjord coasts, they can even be up to 15 km from the open sea. The altitude distribution can reach up to 700 m in mountainous regions.
nutrition
The Atlantic shearwater mainly feeds on small schooling fish such as the Atlantic herring , the European sprat or sand eels ( Ammodytes marinus ). Occasionally cephalopods , crustaceans or debris floating on the surface are added. The prey is usually caught briefly immersing or pursued while diving, but sometimes it is also picked from the surface.
The foraging takes place individually or in small, species-specific groups. Sometimes the species socializes with fin whales or chinstrap dolphins or follows fishing trawlers. In the northwestern Atlantic, it is often found in the area of golf rods .
Reproduction
Atlantic shearwaters become sexually mature between the ages of five and seven. Many do not return to the breeding colonies until they are three or four years old and a large number only brood from the seventh year on. The breeding site loyalty is very pronounced in males, but less in females. Up to 50% of young females migrate and look for a partner elsewhere. The birds live a lifelong, monogamous marriage, but presumably hibernate separately. There is an annual brood.
The species breeds in sometimes very large colonies, the locations of which offer favorable take-off options and must be as safe as possible from enemies of the ground. The breeding caves between 50 and 100 cm deep are partly dug themselves, partly burrows by wild rabbits , natural crevices or cavities under rocks are used. They are laid out with feathers, grass, ferns or roots from the vicinity of the nest.
The colonies are occupied from March onwards, after which the females leave them again for a two to three-week foraging flight, during which they migrate in a south and south-westerly direction. The activities at the nesting site take place exclusively at night, copulation in the cave or in front of it. The main season of laying is in the first May decade in South Wales, and probably earlier in Macaronesia .
The clutch consists of a single, white egg that is approximately 60 mm × 41 mm in size and is incubated between 47 and 66 days. The partners alternate about every three to five days, sometimes only after eight to ten days. One stays on the nest, the other undertakes a multi-day, up to 1000 km long foraging flight. The average length of a “shift” is 7.3 days for males and 5.8 days for females.
After hatching, the young are flocked for a week, then fed every day and a half by the male and every two days by the female. After 65 to 81 days, the boy leaves the cave and goes on foot to the edge of the cliff in order to fly out to sea.
The breeding success is usually between 62 and 75%. In rainy summers or years of food shortage, it can drop to around 44%.
Mortality and Age
Atlantic shearwaters can get very old. The oldest ring bird reached an age of more than 52 years and is thus one of the oldest birds ever recorded by ring finds. However, the average age is 7 years. In the first few years, the survival rate is around 33%, from the age of four it increases to 90%.
The predators of this species include large gulls such as the black-headed gull or skuas . Large numbers of adult birds can fall victim to these in colonies. Locally, these losses can run into the thousands. Fledglings can die from puffinosis . In Wales, the death rate from this disease is around 4% annually. Sometimes the species ends up as bycatch in fishing nets.
literature
- Carles Carboneras, Francesc Jutglar, Guy M. Kirwan : Manx Shearwater (Puffinus puffinus) . (2014), in: J. del Hoyo, A. Elliott, J. Sargatal, AD Christie, E. de Juana (Eds.): Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona 2014.
- Urs N. Glutz von Blotzheim , KM Bauer : Handbook of the birds of Central Europe. Volume 1: Gaviiformes - Phoenicopteriformes. AULA-Verlag, Wiesbaden 1993/2001 (first edition 1966), ISBN 3-923527-00-4 , p. 195 f.
- Hans-Günther Bauer, Einhard Bezzel, Wolfgang Fiedler (Hrsg.): The compendium of birds of Central Europe. Aula-Verlag, Wiebelsheim 2012, ISBN 978-3-89104-758-3 .
- Oscar J. Merne, Pierre Yésou: Puffinus puffinus in Ward JM Hagemeijer, Michael J. Blair: The EBCC Atlas of European Breeding Birds - their distribution and abundance , T & AD Poyser, London 1997, ISBN 0-85661-091-7 , Pp. 22-23
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z Carboneras et al. (2014), see literature
- ↑ a b Glutz von Blotzheim (1993/2001), p. 195 f, see literature
- ^ Lars Svensson, Killian Mullarney, Dan Zetterström: The new cosmos bird guide , 2nd edition. Franckh-Kosmos Verlags-GmbH, Stuttgart, 2011, ISBN 3-440-12384-7
- ↑ a b c d e Glutz von Blotzheim (1993/2001), p. 200, see literature
- ↑ a b c Glutz von Blotzheim (1993/2001), p. 196, see literature
- ^ M. Brooke: Albatrosses and petrels across the world . Oxford University Press, Oxford 2004, referenced in Carboneras et al., See literature
- ↑ Merne / Yésou (1997), see literature
- ↑ a b c Airam Rodríguez, Beneharo Rodríguez, Rubén Barone, Bernadino Pérez, Abraham Hernández: Status and conservation requirements of Manx Shearwaters Puffinus puffinus on Tenerife (Canary Islands) , Alauda 76/1, 2008, pp. 72-74
- ↑ BirdLife International: Species Factsheet - Manx Shearwater ( Puffinus puffinus ) . Retrieved May 31, 2015.
- ↑ a b Maria Pitta Groz, LR Monteiro, JC Pereira, AG Silva, JA Ramos: Conservation of Puffinus species in the Azores , Airo 15, 2005, pp. 11-17, ( PDF )
- ↑ Glutz von Blotzheim (1993/2001), p. 199, see literature
- ↑ Glutz von Blotzheim (1993/2001), p. 201, see literature
- ↑ a b Glutz von Blotzheim (1993/2001), p. 199, see literature
- ↑ Bauer et al. (2012), p. 220, see literature
- ↑ Bauer et al. (2012), p. 219, see literature
Web links
- Puffinus puffinus in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Accessed March 8, 2014.
- Feathers of the Atlantic Shearwater