How do penguins defend themselves from predators

Galápagos penguin

The Galápagos penguin (Spheniscus mendiculus) counts within the penguin family (Spheniscidae) to the genus of the African penguins (Spheniscus). In English the bird is called Galapagos penguin.

description

Appearance and dimensions

The Galápagos penguin reaches a height of 42 to 49 centimeters and a weight of 1,700 to 2,500 grams. Females remain a little smaller and lighter than males. Otherwise the sexes show no dimorphism. Within the genus of the African penguins (Spheniscus) Galápagos penguins are among the smallest representatives. The plumage is predominantly black in color. White parts of the plumage appear in the area of ​​the throat and on the abdomen. The chest is marked by a wide, dark colored transverse band. A narrow white band also extends from the sides of the head to the area of ​​the lower throat. The beak is essentially black in color, the underside of the beak shows a pale pink color from the base of the beak to the middle of the beak. The feet are webbed. Each of the three toes ends in black claws that are suitable for digging. The wings are long and narrow, they sit on the side of the body. On land they are used for balance, in water for locomotion. Once a year there is a change of plumage, which usually takes place shortly before the breeding season.

Way of life

Galápagos penguins live in larger colonies. This applies to both the mating season and the rest of the year. Life in colonies makes sense as it minimizes the risk of carnivores. On land, Galápagos penguins, like all penguins, move awkwardly and slowly. The waddling gait is characteristic. This changes when they step into their real element, water. Here they are considered to be fast and agile swimmers. Galápagos penguins are not very territorial, but they defend their breeding grounds from other species and carnivores. In the water they claim a grazing area near the coast. However, this is not about the food source of a single bird, but of an entire group or colony. The size of the foraging area depends heavily on the food supply. The communication with each other seems to work primarily via different exclamations. It is not known to what extent gestures are also used for communication. Carnivores encounter Galápagos penguins with excited wings flapping and loud cries.

distribution

Galápagos penguins are endemic to the Galápagos Islands. The Galápagos Islands are located in the western Pacific around 1,000 kilometers off the coast of Ecuador and essentially consists of 22 medium-sized to larger islands and a number of small islets. The islands belong to the national territory of Ecuador. The main populations of the Galápagos penguins live on the two islands of Fernandina and Isabela. Isabela is also the largest island in the archipelago. The penguins live on the coasts of these islands. They can be found on both rocky and sandy shores. Natural heights in rocks or self-dug caves in the dune area serve as nesting sites.

Predators

Natural carnivores on land include red cliff crabs (Grapsus grapsus), Galápagos buzzard (Buteo galapagoensis), Short-eared Owl (Asio flammeus galapagoensis) and Barn Owl (Tyto alba) also rice rats (Oryzomys) like the Galápagos rice rat (Oryzomys galapagoensis). However, introduced predators cause far greater damage. Above all, this includes overgrown ones Domestic cats (Felis silvestris forma catus) and domestic dogs. Sharks in particular chase the Galápagos penguins in the water. The eggs are laid in caves relatively protected. The adult animals vehemently defend their clutch against carnivores. As a rule, the animals always appear in groups and thus have a very good chance of defending themselves and their clutch. In the water they are protected on the one hand by their high swimming speed and on the other hand by their black and white camouflage color. Especially the whitish belly side makes it almost invisible in the water when viewed from below.

nutrition

Galápagos penguins feed on smaller fish as carnivores (Pisces), small crustaceans (Crustacea), Molluscs (Mollusca) and other invertebrates that they prey in the sea. Pegs (Clupeidae), Anchovies (Engraulidae) and mullets (Mugilidae) belong to the preferred food. Galápagos penguins search for food in coastal waters and usually dive to depths of up to 20, rarely up to 30 meters. The hunt usually takes place in smaller to larger groups. The localization of prey takes place via the well-developed sense of sight, a prey animal is grabbed with the beak and swallowed whole.

Reproduction

The females of the Galápagos penguins reach sexual maturity at three to four years of age, while males do not go there until around two years later. The mating season does not depend on the climate and can take place all year round. However, Galápagos penguins only breed when there is plenty of food available in the sea. In good years there can be two or three clutches. The main breeding season extends over spring. Galápagos penguins live in a monogamous marriage that often lasts a lifetime. Whether a couple has to find each other or it is a couple, copulation is always preceded by an elaborate courtship. The courtship is therefore used on the one hand to find a couple and on the other hand to strengthen an existing bond. Courtship behavior includes mutual cleaning of their plumage and mock duels with the wings in the form of a dance. Before the actual copulation, it is time to build the nest. The nest is usually created in natural caves, mostly in rocks. The inside of the breeding cave is lined with pebbles, branches and other materials. The materials are collected on the beach or simply stolen from other nests. This often leads to friction.

Existing nests are only repaired. The copulation takes place immediately in front of the brood cavity. Galápagos penguins are colony breeders that breed in large colonies. However, each individual breeding site is considered a small area and is defended against conspecifics. The defense of the entire breeding area against carnivores takes place collectively. In the course of copulation, the male mounts his female. The female lays down on the ground for a long time. The copulation takes place quickly and painlessly, it extends from a few seconds to a maximum of a minute. The copulation is repeated several times at intervals.

The female lays two eggs per brood in the brood cavity. The eggs are warmed by both sexes over a period of 38 to 42 days. During this time, an adult bird is always present in the brood cavity, the other parent is foraging for food. A couple proceeds in a similar way after the chicks have hatched. Both parents provide the chicks with food for a period of a good two months. It is a pre-digested food pulp made from fish and other marine animals. At the age of three to four months, the young penguins are independent. Life expectancy in wild populations is 15 to 20 years. Mortality in the first few years is quite high due to the large number of carnivores and unfavorable climatic conditions. Only a small proportion of the animals reach sexual maturity.

ecology

On the Galápagos Islands, Galápagos penguins compete with humans for food. Therefore, they have been persecuted for a long time. The fishing industry in particular complains of great losses in the income of fishermen. It is true, however, that there is no significant damage, since the penguins only eat small fish. The ecological equilibrium is only unbalanced through the overexploitation of nature. The fishing grounds off the Galápagos Islands are already completely overfished. Tourism has been established for several years. This enables some of the fishermen to find new sources of income today.

Hazard and protection

Galápagos penguins are now one of the most endangered species of penguin. In the IUCN Red List, the species is therefore listed as Endangered (endangered). The main reasons are the decades-long hunting by humans, the disturbances by humans in the breeding colonies, the introduction of predators (Neozoa), the water pollution by dumped waste oil and the food shortage due to overfishing of the foraging grounds. Another dramatic risk factor has emerged in the last few decades from the El Niño climate phenomenon. El Niño refers to the occurrence of non-cyclical, changed currents in the oceanographic-meteorological system of the Pacific in the area of ​​the equatorial line. As a result of this phenomenon, the Humboldt Current weakens significantly. The Humboldt Current brings nutrient-rich water to the coasts of the Galápagos Islands. Due to the weakening of the Humboldt Current, the region becomes impoverished in terms of the nutrients present in the water. As a result, the food supply for the Galápagos penguins is also decreasing. Many Galápagos penguins starve to death during El Niño.

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See also

  • Main Products: Birds (Aves)

Literature and sources

  • Boris M. Culik & Rory P. Wilson: The world of the penguins. Survivors in ice and sea. Blv Book Publishing; 1993 ISBN 3405144760
  • Prof. Dr. Dr. hc Bernhard Grzimek: Grzimek's animal life. Volume 7-9 birds. Deutscher Taschenbuch Verlag GmbH & Co. KG Munich (1993) ISBN 3-423-05970-2
  • Gottfried Mauersberger, Wilhelm Meise: Urania animal kingdom, 7 vols., Birds.Urania, Stuttgart (1995) ISBN 3423032049
  • Einhard Bezzel, Roland Prinzinger: Ornithology, Utb, 1990, ISBN 3800125978
  • Hans-Heiner Bergmann: The biology of the bird. Auditorium, 1987, ISBN 389104447X

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