Galápagos penguin

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Galápagos penguin
Galápagos penguin

Galápagos penguin

Systematics
Class : Birds (aves)
Order : Penguins (Sphenisciformes)
Family : Penguins (Spheniscidae)
Genre : African penguins ( Spheniscus )
Type : Galápagos penguin
Scientific name
Spheniscus mendiculus
Sundevall , 1871

The Galápagos penguin ( Spheniscus mendiculus ) is one of four species in the genus of the African penguins ( Spheniscus ). It occurs worldwide only on the Galápagos Islands and is the rarest penguin species with around 1,200 individuals (as of 2004). It is threatened with extinction. On the red list of endangered animal species it has the status EN ('endangered', in the German list 'endangered'). Since the Galápagos Islands are located on the equator , the Galápagos penguins of Isabela Island are the only penguin species that also breed in the northern hemisphere.

Appearance

Galápagos penguins are between 48 and 53 centimeters tall and weigh between 1.5 and 2.5 kilograms. The males are slightly larger and heavier. Both sexes have their maximum weight immediately before moulting , the minimum weight immediately afterwards (males) or after oviposition (females).

The back plumage is dark and the abdominal plumage is white and may have dark spots. Like all African penguins, the Galápagos penguin has a white band that begins at the eye and runs in an arc to the base of its beak. A white stripe also runs around the belly in the shape of a horseshoe. However, this drawing is less clear in him than in the other species. The beak is black and on the underside a white band extends to the tip of the beak.

At the base of the beak, the animals have featherless patches of skin that are pink because of the strong blood circulation. These are used for heat exchange and thus prevent the animals from overheating. It is believed that the skin spots play a role in identifying the breeding partner, as Galápagos penguins do not display any of the greeting rituals typical of other penguin species.

The plumage of the chicks is light gray and may lighten a little around the eyes. When the chicks get older, they develop gray-white plumage that has no stripes. After the first moult, the young get their adult plumage.

Distribution and population development

Distribution of the Galapagos penguin

The distribution of the Galápagos penguin is restricted to the Galápagos Islands. 95% of all breeding pairs can be found in the colonies on the main island Isabela and the offshore island Fernandina ; the rest of the animals are on Santa Cruz .

The population was estimated at around 1200 sexually mature specimens in 2004, and the population is believed to have been nearly stable since 1999. It is now assumed that the estimate from 1971, which was based on 3400 sexually mature animals, was too high and must be corrected to 2100 specimens. As a result of various events - the eruption of the Chico volcano in 1979, a strong El Niño effect in 1982/83, the increase in pollution of the oceans and the increase in fishing - the number fell to around 500 animals in the 1980s . By the mid-1990s, the population was able to recover to an estimated 1950 animals. Another strong El Niño from 1997 to 1998 led to another drop by almost a third to the above figure.

Reproduction and nutrition

Galápagos penguins are not persistent divers, they can only stay under water for 90 seconds, but can reach depths of up to 15 meters; however, on average they hunt at depths of three meters.

The main food of the Galápagos penguins is the fish, which they hunt as a group. Their main prey are small fish from the herring-like order (Clupeiformes) such as sardines and anchovies . When hunting, the prey fish are driven into bays and locked there. In the open water, the penguins try to form their prey by circling them into so-called fish pillars, in which the penguins take turns to catch their prey.

Galápagos penguins are cave breeders . The breeding cave is usually created in sufficiently deep guano layers; Volcanic crevices are rarely used, which are then padded with nesting material such as seaweed or other plant material. The penguins' breeding cycle is irregular and seems to be dependent on the water temperature - which in turn is responsible for the food supply. It can happen that breeding pairs breed up to three times a year. It also happens that the penguins moult during the breeding season, which is unusual for penguins. When there is enough food, the penguins eat the necessary cushion and start breeding. The clutch consists of two eggs laid three to five days apart. The pairs incubate for around 40 days until the young hatch at different times. During the first three weeks, an adult animal always stays at the nest in order to prevent the chicks from overheating, which at that age are not yet able to regulate their body temperature independently. As a result, only one parent animal is able to provide the young with food, so that the competition between the two chicks in an unfavorable feeding situation leads to only the stronger one being fed and the weaker one slowly dying. After this time, however, both parents feed the chicks for another eight weeks until they are independent.

Enemies and Endangerment

Unlike the Antarctic species, for example, Galápagos penguins not only have enemies in the water, but also on land. The short- eared owls ( Asio flammeus ) and the Galapagos buzzard ( Buteo galapagoensi ), native to the Galápagos Islands , occasionally hunt penguins. Dogs, cats and rats introduced by humans can also pose a threat to the animals and their breeding colonies. In the water, different types of requiem sharks , the orca ( Orcinus orca ), the Galápagos sea lion ( Zalophus wollebaecki ) and the Galápagos fur seal ( Arctocephalus galapagoensis ) are among their predators. Chicks and eggs are also endangered by native snakes and the red cliff crab ( Grapsus grapsus ).

Ultimately, the greatest danger for the species is El Niño, which can ruin the breeding success of a whole season by not getting the necessary food and kill a not inconsiderable number of adult animals in one fell swoop.

Web links

Commons : Galápagos Penguin  - Collection of images, videos and audio files

Single receipts

  1. ↑ Martin Walters: The signals of the birds - What birds reveal about the environment . Haupt, Bern 2011, ISBN 978-3-258-07682-9 . , P. 121