Shearwater

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Shearwater
Audobon's Shearwater.jpg

Shearwater ( Puffinus lherminieri )

Systematics
Class : Birds (aves)
Order : Tubular noses (Procellariiformes)
Family : Petrels (Procellariidae)
Genre : Shearwater ( Puffinus )
Type : Shearwater
Scientific name
Puffinus lherminieri
Lesson , 1839

The shed shearwaters ( Puffinus lherminieri ) is a tropical seabird from the family of the Petrels (Procellariidae). The species was first described in 1839 by the French doctor and naturalist René Primevère Lesson and is sometimes referred to as the Audubon shearwater (after the American ornithologist John James Audubon ). The specific epithet lherminieri honors the French doctor and naturalist Félix Louis L'Herminier .

description

Detail drawing of the head ( August von Pelzeln , 1873)

The shearwater is a small to medium-sized, stocky sea bird with an average length of about 30 cm and a weight of about 170 g. Size and weight can vary between populations, but rarely exceed values ​​of 33 cm in length and 230 g in weight. The wingspan is on average 70 cm. The plumage shows a dark brown to blackish color on the upper side as well as on the underside of the tail and the flight feathers. The rest of the underside, as well as the throat and cheeks, are colored white. It can be confused with the similarly colored Atlantic Shearwater, but it has a white underside of its tail, which allows the species to be differentiated. Juvenile specimens show a grayish color of the down all over their body .

The animals have a streamlined body that is much better adapted to gliding on thermal winds than to a terrestrial way of life. The legs sit quite far back on the body, which on land leads to an awkward-looking locomotion that tends to crawl on the chest. The beak is thin and elongated and shows a slight hook shape that makes it easier to grasp and hold onto slippery prey.

Diet and Lifestyle

The shearwater is highly adapted to life in the open water and is rarely found on land outside of the breeding season, even overflights are rare during the day and on nights with strong moonlight. The species often stays at the edge of ocean currents or over underwater elevations to feed ; the food is consumed during the flight or while floating on the water. Common shearwaters often form large schools together with other species. The diet varies greatly between populations and subspecies. Studies show the frequent ingestion of small fish (found in the stomachs of 94.1% of the animals examined), squid (65.5%) and crustaceans (6.3%). In contrast to this, there is also a population off the coast of the US state of North Carolina that has specialized in the consumption of brown algae of the Sargassum genus . When hunting, the birds immerse their whole bodies in the water, the depth here varies from a few centimeters to a few meters.

Reproduction

Young animal in the nest in a cave on Little Tobago

The shearwater nests in small colonies on various islands in the Caribbean , where the animals arrive up to three months before they lay eggs. The individual breeding pairs often stay together for a longer period of time and show a pronounced mating behavior in which the birds rub their beaks together and emit loud calls, which can be heard from a great distance, especially at night. The nests are usually built in narrow crevices on steep cliffs , but nest building has also been observed in small caves on the ground or under dense vegetation. The nest itself is simply built and often nothing more than a small depression in the ground.

The females lay a single white egg per season. It is incubated by both parents alternately until the young hatch after about 51 days. The brood care and feeding of the offspring is then also carried out by both sexes and usually takes place at night. This takes about 70 days, another three to five days later the juvenile animals leave the nest for good. To do this, they climb the highest point nearby during the night and start their first flight out to sea from there. Successful breeding pairs can then raise a young again within about nine to ten months. The offspring of the long-lived species need about eight years to reach sexual maturity themselves.

Systematics and distribution

Specimen of the subspecies Puffinus lherminieri bailloni on La Réunion

The taxonomy of petrels is considered by experts to be extremely complex and controversial. Originally, numerous subspecies with a pantropical range that includes the Atlantic , Pacific and Indian Oceans were grouped under the species Puffinus lherminieri . Recent phylogenetic studies by Austin et al. in 2004, however, showed that many of the previously considered as subspecies populations only by convergent evolution -related, morphological similarities to Puffinus lherminieri exhibit and a closer relationship status is not given. According to the current state of research , four other subspecies are considered valid in addition to the nominate form Puffinus lherminieri lherminieri , which occurs in the area of ​​the Bahamas and the West Indies . These are in detail:

In addition, two other possible subspecies should be mentioned here, which were not considered in the more recent studies and which therefore cannot be excluded as belonging to Puffinus lherminieri :

Danger

The shearwater is currently classified by the IUCN as not endangered, primarily because of its extremely large distribution area (status: least concern ). In 2018, however, the organization noted a general decline in the population of the shearwater compared to previous years. However, this decline was not seen as serious enough to give the species the status “endangered” ( vulnerable ). Nevertheless, the species is mentioned in Appendix I of the European Birds Directive and Appendix II of the Bern Convention . One of the main threats to the shearwater is the predation of eggs and young birds in breeding colonies by domestic rats, some of which are introduced by humans . A study carried out in the French West Indies in 2008 showed that the breeding success of the birds increased from virtually 0% to around 85 to 90% after the local rat population had been removed. Another significant problem is light pollution in many breeding areas. The animals are attracted by the lighting at night, lose their orientation and cannot find their way back to their breeding grounds. In addition, factors such as marine pollution , increasing tourism and the trapping of birds for consumption or bycatch also play a role in the decline in population numbers.

heraldry

Head of a shearwater on the Saba coat of arms

The shearwater is the national bird of the Dutch island of Saba , where one of the most important breeding colonies of the species is located. A picture of the bird's head is therefore prominently on the island's coat of arms . The birds are also called "Wedrego" by the island's locals, as their call should sound like the English sentence Where'd we go (German for example: "Where did we go?").

literature

  • Chandler S. Robbins, Bertel Bruun, Herbert S. Zim: Birds of North America: A Guide To Field Identification . 2nd Edition. St. Martin's Press, 2001, ISBN 978-1-58238-090-2 .
  • Steve NG Howell, J. Brian Patteson, Debra Shearwater: Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide . Princeton University Press, Princeton, NJ 2012, ISBN 978-0-691-14211-1 .
  • Carles Carboneras: Handbook of the birds of the world - Volume 1 Ostrich to Ducks . 1st edition. Lynx Edicions, 1992, ISBN 978-84-87334-10-8 .

Web links

Commons : Shearwater ( Puffinus lherminieri )  - Collection of images, videos and audio files

Individual evidence

  1. ↑ René Primevère Lesson: Description de treize oiseaux nouveaux, suivies de rectifications sur quelques espèces déjà publiées . In: Revue Zoologique par La Société Cuvierienne . tape 2 , 1839, p. 100-104 .
  2. ↑ Adrian Delnevo: Things that go bump in the night. In: dcnanature.org. Dutch Caribean Nature Alliance, December 2013, accessed on August 14, 2018 .
  3. ↑ Steve NG Howell, J. Brian Patteson, Debra Shearwater: Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide . Princeton University Press, Princeton, NJ 2012, ISBN 978-0-691-14211-1 , pp. 125 .
  4. ↑ a b Audubon's Shearwater. In: animalcorner.co.uk. Retrieved August 15, 2018 .
  5. ↑ Audubon's shearwater fact file. In: arkive.org. Archived from the original on August 15, 2018 ; accessed on October 1, 2019 (English).
  6. ↑ Will Mackin, David Lee: Audubon's Shearwater - Biology. In: wicbirds.net. 2009, accessed on August 14, 2018 .
  7. ↑ Kenn Kaufman: Audubon's Shearwater. In: audubon.org. National Audubon Society, accessed August 14, 2018 .
  8. ↑ Audubon's Shearwater - Interesting Facts. In: whatbird.com. Archived from the original on August 15, 2018 ; accessed on October 1, 2019 (English).
  9. ↑ Jeremy J. Austin, Vincent Bretagnolle, Eric Pasquete: A global molecular phylogeny of the small Puffinus shearwaters and implications for systematics of the Little-Audubon's Shearwater Complex . In: The Auk . tape 121 , 2004, p. 847-864 , doi : 10.1642 / 0004-8038 (2004) 121 [0847: AGMPOT] 2.0.CO; 2 .
  10. ↑ Persian Shearwater. In: hbw.com. Handbook of the Birds of the World Alive, accessed November 29, 2019 .
  11. ↑ Michel Pascal, Olivier Lorvelec, Vincent Bretagnolle, Jean-Michel Culioli: Improving the breeding success of a colonial seabird: a cost-benefit comparison of the eradication and control of its rat predator . In: Endangered Species Research . tape 4 , no. 3 , 2008, p. 267-276 , doi : 10.3354 / esr00080 .
  12. ↑ Puffinus lherminieri. In: iucnredlist.org. BirdLife International, accessed August 14, 2018 .
  13. ^ Coat of arms. In: inyourpocket.com. Retrieved November 29, 2019 .
  14. ↑ Audubon's Shearwater. In: dcnanature.org. Dutch Caribbean Nature Alliance, 2014, accessed November 29, 2019 .