Thick-billed penguin
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Thick-billed penguin ( Eudyptes pachyrhynchus ) |
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| Gray , 1845 |
The thick-billed penguin or Fiordland penguin ( Eudyptes pachyrhynchus ) is a species of penguin that can be found in southern New Zealand and the offshore islands . It belongs to the genus of the crested penguins .
The Dickschnabelpinguin belongs together with the Galapagos penguin and the yellow-eyed penguin among the rarest penguin species and is used by the IUCN currently considered endangered ( vulnerable classified).
Appearance
The thick-billed penguin reaches a body length of up to 55 centimeters. Weight varies considerably within a year and is also influenced by gender. Males weigh between 3 and just under 5 kilograms, while females weigh between 2.5 and 4.8 kilograms. They show the lowest weight and the highest weight before the moult. The sexual dimorphism is not very pronounced, females are just generally slightly smaller and have a slightly less powerful beak. In the case of couples, the gender can usually be determined based on the size difference. Not yet sexually mature birds with an age of one to two years can hardly be distinguished from sexually mature ones by their appearance.
Adult birds have black heads, black cheeks, and black chin. The upper part of the throat is also black. The thick-billed penguin differs from other crested penguins by the three to six white stripes on its cheek and the pale yellow to sulfur-yellow feathers that stretch from the beak to the top of the head. At the back of the head, these feathers are a little less than five centimeters long. The upper body is blue-black. Immediately before moulting, however, the plumage looks a little paler and browner. The underside of the body is whitish. A sharp, straight line separates the black throat from the underside of the body.
There is a possibility of confusion with the other species of crested penguins . It is particularly similar to the snare island penguin . Thick-billed penguins that are not yet sexually mature can be confused with rockhopper penguins that are not yet sexually mature . The snare island penguin, however, lacks the white cheek strips and has a longer beak. Young rockhopper penguins have a not yet sharply demarcated over-eye stripe that starts much further back than the thick-billed penguin.
Distribution area
The thick-billed penguin only breeds in New Zealand. Breeding colonies are on the western and southwestern coasts of the South Island as well as on some islands off the coast. Stewart Island , a large island 30 kilometers off the South Island, and the Solander Islands are among the most important . The breeding areas are in rainforests of the moderate latitudes on fjords, bays and peninsulas. Breeding colonies are typically found on steep slopes that are densely overgrown with climbing plants and ferns, mosses and liverworts . However, they can also be found on rockier coastlines, where they breed in rock caves, scree slopes and under rock overhangs.
The range outside of the breeding season has not yet been adequately investigated. All that is certain is that thick-billed penguins do not stay near their breeding colonies from March to June. Wandering guests are also observed on other parts of the coast of New Zealand as well as on the Australian coast.
Food and subsistence
Thick-billed penguins mainly live on cephalopods , crustaceans and fish. As the data from GPS trackers with which scientists provided 17 adult animals shows, they cover long distances on the way from their nesting to the feeding area. One region where they caught their food is around 800 kilometers south of Tasmania, another in the sub-Antarctic Sea south of the Tasmanian feeding ground. The animals move up to 2500 km from their nesting place.
Breeding behavior
The courtship behavior of the thick-billed penguins is very similar to the behavior of other crested penguins. However, the thick-billed penguin basically shows a less social way of life than other representatives of this genus. Aggressive gestures within the species include a beak threatening with an open beak. Thick-billed penguins grab each other by the beaks in direct disputes. This behavior can be observed particularly in penguins that have occupied nesting sites next to each other. Thick-billed penguins occasionally try to grab their necks or flap their fins-shaped wings. Occasionally, they will also raise their fins, bend forward, and take a few steps toward their opponent. They call out loud.
Big-billed penguins visit their breeding area between June and July. The breeding colonies are generally small, they sometimes even nest individually. The nests are typically two to three meters apart. The nests are usually optically isolated from each other due to the dense vegetation between which the thick-billed penguins breed. The nest consists of a shallow hollow with a diameter of 30 centimeters. The hollow is occasionally covered with fern leaves and leaves of other plants, small sticks or stones. It is often found on or even under a tree root, between rocks or in small hollows.
The clutch consists of two eggs that are usually laid between July and August. The laying interval between the eggs is usually 4 days. The first egg is usually a little lighter and weighs 99 to 100 grams. The second egg weighs between 116 and 120 grams. Both parent birds are involved in the incubation of the eggs. The incubation period of 30 to 36 days can be divided into three phases. The two parent birds share during the first five to ten days. During the second phase of 13 days, only the male incubates. In the third phase, which also lasts thirteen days, the egg is only incubated by the female. The newly hatched chick is guarded and flocked by the male for two to three weeks. During this time, the female usually returns to the breeding colony every day and provides the chick or chicks with food. The chicks then form loose groups of young birds (also often called “kindergartens” in literature). During this time, both parent birds feed their offspring.
A maximum of one young bird per clutch will fledge, this is usually the young bird that hatches from the second egg laid. The number of breeding pairs that incubate two eggs in the last phase varies between 68 and 83 percent per year. Where two young birds hatch per clutch, one of the two young birds usually dies within the first seven days. Young birds are usually 75 days old when they fled.
Stock and predators
The population is currently estimated by the IUCN at 5,000 to 6,000 sexually mature individuals. Since there is very little historical data on distribution and breeding populations, no clear population trend can be determined. Dogs are considered to be a major disruptive factor in the colonies. Rats and the Wekaralle eat eggs and young birds. The influence of the Wekarallen varies depending on the location of the colonies. In some colonies, 38 percent of egg losses are attributed to this bird. Among the predators of the thick-billed penguins are the New Zealand sea lions , New Zealand fur seals , killer whales and sharks .
literature
- Tony D. Williams: The Penguins . Oxford University Press, Oxford 1995, ISBN 0-19-854667-X
Web links
- Eudyptes pachyrhynchus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 22 of 2008.
- Videos, photos and sound recordings of Eudyptes pachyrhynchus in the Internet Bird Collection
Individual evidence
- ↑ BirdLife factsheet on the thick-billed penguin , accessed November 8, 2010
- ↑ Williams, p. 196
- ↑ Williams, p. 195
- ^ Williams, p. 195 and p. 196
- ^ Williams, pp. 197 and 198
- ^ Williams, p. 198
- ↑ Williams, p. 196
- ↑ Thomas Mattern, Klemens Pütz, Pablo Garcia-Borboroglu, Ursula Ellenberg, David M. Houston, Robin Long, Benno Lüthi, Philip J. Seddon: Marathon penguins - Reasons and consequences of long-range dispersal in Fiordland penguins / Tawaki during the pre -moult period. August 29, 2018, PLOSONE, doi: 10.1371 / journal.pone.0198688
- ^ Williams, p. 198
- ^ Williams, p. 198
- ^ Williams, p. 199
- ^ Williams, p. 199
- ^ Williams, p. 200
- ↑ BirdLife factsheet on the thick-billed penguin , accessed November 8, 2010
- ↑ Williams, p. 196
- ^ Williams, p. 200
- ^ Daniel Gilpin: Penguins . Parragon Books Ltd., 2007, ISBN 978-1-4075-0629-6 .