Rockhopper penguin
| Rockhopper penguin | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Rockhopper penguin ( Eudyptes chrysocome ) |
||||||||||
| Systematics | ||||||||||
|
||||||||||
| Scientific name | ||||||||||
| Eudyptes chrysocome | ||||||||||
| ( Forster , 1781) |
The Rockhopper penguin ( Eudyptes chrysocome ) is a bird art from the family of penguins (Spheniscidae). The rockhopper penguin is the smallest species within the crested penguin genus . The average life expectancy is 10 years.
There are now only two subspecies recognized, which differ in body size, the length of the hood feathers and the drawing on the underside of the fins. The northern rockhopper penguin , formerly known as Eudyptes chrysocome moseleyi , is now regarded as a separate species.
Appearance
Rockhopper penguins reach a height between 45 and 58 centimeters and a weight of 2.3-4.5 kg. The weight varies considerably over the course of a year, generally they are heaviest just before moulting and can be up to 3.8 kilograms. Less well fed rockhopper penguins occasionally weigh as little as two kilograms. Basically, they are among the smallest penguins ever. There is no noticeable sexual dimorphism , but females tend to be somewhat smaller. The plumage shows no seasonal variations. Young birds can be distinguished from adult rockhopper penguins up to an age of two years by their plumage.
Adult birds have a narrow yellow stripe over the eyes, the feathers of which are greatly elongated and stick out behind the eye; Further towards the back of the head, these feathers are striped lengthways with yellow and black, where they form a loosely attached tuft. The eyes are red, the short, strong and bulging beak is reddish-brown, feet and legs are pink, the soles are black. The head and face are otherwise black. The top of the body is dark slate gray. Freshly moulted plumage has a bluish shimmer. Worn plumage shortly before moulting looks brownish. The underside of the body is white and sharply set off from the black throat. The wings are transformed into fins and are blue-black on the top and white on the underside.
Young birds are smaller than adult birds. Their chin and throat are gray. The beak is smaller and more dull in color. They either do not have any elongated feathers or they are significantly shorter than those of the adult birds. The plumage of the chicks is completely black and without any markings, as is the beak. Immature animals can be recognized by a dull yellow line over the eye and a red-brown beak, but a lack of tufts.
behavior
Although the animals are relatively small, they are considered to be able to defend themselves against much larger disturbances. Rockhopper penguins indiscriminately attack any animal that comes near their nest, whether other penguins, albatrosses or humans. On the other hand, the animals are extremely affectionate towards their partners and social plumage care is common.
Way of life
nutrition
Rockhopper penguins are food generalists; they eat everything they can catch and consume. Investigations of animals on the Falkland Islands revealed crustaceans (e.g. Euphausia , Thysanoessa , Themisto ), squids ( Gonatus , Loligo , Onychoteuthis , Teuthowenia ) and various small fish in different proportions . They usually hunt in groups, but rarely at depths over 100 m. The average swimming speed is 7.5 km / h. On their forays, the penguins reach depths of up to 170 m.
Reproduction
Rockhopper penguins are not sexually mature before the age of four. The breeding season begins in early October when the males arrive at the nesting site, and the females follow a few days later.
The animals not only return to the same nesting site every year, but also to the same nest , which they repair with stones, sticks, parts of plants or the like. The colonies are preferably located in sloping rock canyons with access to deep water and can reach a size of up to 100,000 nests with a density of 1.5 to 3 nests per square meter. Albatrosses and cormorants often breed in the colonies and there is open fresh water in their vicinity, as the animals bathe and eat fresh water regularly. The vegetation at the colony sites consists of grasses and low dwarf shrubs; Nesting sites that have been in use for a long time, however, have no vegetation.
As soon as the females arrive, copulations begin. At the beginning of November, two eggs are laid four to five days apart, the first weighs around 80 grams, the second around 110 grams. The second egg is behind the first, where the temperature is most stable and the egg is less likely to be lost or stolen. With the subspecies Eudyptes c. moseleyi and Eudyptes c. filholi there is almost never more than one fledgling chick, with the nominate form, however, two healthy chicks are not unusual under good conditions.
The parents incubate the eggs for around 33 days, alternately in three layers of almost the same length. In the first layer both parents are at the nest, in the second only the female breeds, in the third only the male; the other partner goes hunting. For the first 25 days after the chicks hatch, the male remains at the nest. After that, the chicks have developed their second dunen coat, leave the nests and form groups with other chicks that allow both parents to leave the nest and go hunting in order to meet the chick's growing food needs (around 600 per feeding at this time Grams). At the age of 10 weeks the young fledglings, 20 to 25 days later the animals leave the nesting site.
Enemies
Adult animals have no natural enemies on land, but in the sea they are prey to sharks , orcas , fur seals , maned seals and sea lions . Eggs and chicks are eaten by skuas , gulls and vulture falcons . On some islands, enemies have also been introduced by human hands, such as cats and rats.
Distribution, population development and status
The rockhopper penguin is the most common species of the genus. The distribution area extends from South America to New Zealand and includes two spatially separated areas of subtropical to sub-Antarctic islands, each of which is populated by a subspecies. The brood distribution is on the islands around the Antarctic between 37 and 53 degrees south latitude. The maritime distribution extends over the southern parts of the Atlantic , Pacific and Indic .
The total population was estimated at 3.7 million breeding pairs in 2005, of which, according to a count from 1995 to 1997, around 500,000 pairs belong to the subspecies E. c. chrysocome , but the most common subspecies is E. c. filholi .
The total population of the species has declined dramatically by over 30% in the last 30 years. The decline was most dramatic in the Falkland Islands, the main distribution area of the nominate form ; here the population fell from 2.5 million breeding pairs in 1984 to around 300,000 breeding pairs in 1995, a decrease of 88%. The reason was the overfishing of the waters around the Falkland Islands, which meant that the animals could not build up sufficient fat reserves for the breeding season and hundreds of thousands died of starvation.
Although the Falkland Islands population has recovered and stabilized as a result of legal regulation, the overall population of the species is still declining. The main reason is still fishing, newer threats are mainly ecotourism, marine pollution and climate change, which is changing the food supply. As a consequence of this population reduction, the species is classified by the IUCN as vulnerable , i.e. "endangered".
In captivity, the northern rockhopper penguin is only bred in the Schönbrunn zoo in Vienna with annual offspring. About half of the approximately 80 animals living in European zoos are in Vienna. In 2017 the zoo received two animals that had been landed in Australia because of its rockhopper penguin colony .
Systematics
Two subspecies are distinguished within the species:
- Eudyptes chrysocome chrysocome
- breeds in southern Argentina , southern Chile and the Falkland Islands . Features of the subspecies are the black skin around the beak and a shorter crest on the back of the head.
- Eudyptes chrysocome filholi
- breeds on Kerguelen , Crozet Islands , Macquarie Island , Auckland Islands , Prince Edward and Marion Islands , Heard and McDonald Islands , Campbell Island and Antipode Islands . The stripe of the eyes is very narrow in this subspecies, the feathers have a length of six to seven centimeters. Some scientists believe that the subspecies should become a separate species.
The earlier than subspecies Eudyptes chrysocome moseleyi called Northern Rockhopper penguin who on as Tristan Cunha , Amsterdam and Saint-Paul breeds is a distinct species today moseleyi Eudyptes viewed.
literature
- Mike Bingham: Penguins of the Falkland Islands & South America , pp. 38-47, 2001, ISBN 0-7596-3335-5
- Hadoram Shirihai: A Complete Guide to Antarctic Wildlife - The Birds and Marine Mammals of the Antarctic Continent and Southern Ocean , Alula Press, Degerby 2002, ISBN 951-98947-0-5
- Tony D. Williams: The Penguins . Oxford University Press, Oxford 1995, ISBN 0-19-854667-X
Web links
- Videos, photos and sound recordings of Eudyptes chrysocome in the Internet Bird Collection
- Entry on the species at ARKive
- Eudyptes chrysocome in the Red List of Threatened Species of the IUCN 2009. Posted by: BirdLife International, 2008. Accessed on March 10 of 2010.
Individual evidence
- ↑ a b c d e Daniel Gilpin: Penguins . Parragon Books Ltd., 2007, ISBN 978-1-4075-0629-6 .
- ^ Shirihai, p. 71
- ^ Williams, p. 187
- ^ Williams, p. 185
- ↑ BirdLife International (2007): Species factsheet: Eudyptes chrysocome , Online , accessed December 15, 2007
- ^ Mike Bingham: Penguins of the Falkland Islands & South America , p. 38
- ↑ E. Guinard; H. Weimerskirch; P. Jouventin: Population Changes and Demography of the Northern Rockhopper Penguin on Amsterdam and Saint Paul Islands , in: Colonial Waterbirds, Vol. 21, No. 2. (1998), pp. 223
- ↑ Young rock penguins on ORF from May 4, 2011
- ^ Report from the state radio and television company ORF from December 14, 2017
- ^ Williams, p. 186
- ↑ Jonathan Banks; Amy Van Buren; Yves Cherel; James B. Whitfield (2006). Genetic evidence for three species of Rockhopper Penguins, Eudyptes chrysocome . Polar Biology. 30 (1): 61-67. doi: 10.1007 / s00300-006-0160-3