Indian darter
| Indian darter | ||||||||||
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Male Indian darter |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Anhinga melanogaster | ||||||||||
| Pennant , 1769 |
The Indian darter ( Anhinga melanogaster ), also known as the Indian darter and the oriental darter , is a species of the darter (Anhingidae). Its distribution area includes the south and southeast of Asia . The IUCN has the Indian darter on the early warning level ( near threatened ).
Appearance
When fully grown, the Indian darter reaches a body length of around 85 to 97 cm and weighs between 1050 and 1800 g. The wingspan is 116 to 128 cm.
The Indian darter is, like the other, very similar, darter , a dark-plumed fish eater with a very long neck. The head is brownish to blackish-brown in color, the back is shiny black with conspicuous white or silver-gray or stripes and dots, which are usually a little lighter than those of the closely related Australian and African darters. The shoulder and tail feathers show a fine wave pattern. A thin white line from the forehead to the eye is characteristic of the Indian darter, which is barely visible in the two other related "Old World" species. A noticeable white or pale brown stripe runs from the base of the beak along the sides of the head and the upper neck. In contrast to the other two "old world" species, this strip is generally longer and thinner. The genders are also clearly identifiable when observing the field. Males have a dark underside of the body while that of females is light. However, this difference is smaller than that of the Australian darter. Females also have a gray-brown upper body, but have similar color markings as the males. The iris is light yellow to yellow during the breeding season, and pale yellow to pale brown outside the breeding season.
The beak is quite long with 71 to 87 mm (longer than the head), slender and pointed. The Indian darter often swims in such a way that only its neck and head are visible above the water. What is striking about this species is that it has specially shaped vertebrae in its neck. Because of this, he is able to bend his neck in a z-shape and stretch it jerkily. It uses this during its food acquisition, during which it spears fish with its beak.
distribution and habitat
The Indian darter is found in Iraq, Pakistan, India and southeast Asia including the Malay Archipelago to the Philippines and the Great Sunda Islands. The range of the Australian darter joins from New Guinea.
Its habitat is inland wetlands but also tidal waters near the coast. For its food search it is dependent on open, large bodies of water without large swell and needs branches or dead tree trunks protruding above the water surface in order to rest on it and to dry its wings. It occurs accordingly at lakes, reservoirs, ponds, swamps and river meanders. He avoids water regions with dense aquatic vegetation. On the other hand, the composition of the riparian vegetation is not decisive for whether a body of water offers suitable habitat for it.
Food and foraging
The food spectrum of the Indian darter consists mainly of fish. They also eat insects and other animals in the water zone. It hunts mostly solitary, but several birds can gather on rich food grounds. However, they do not form groups that eat together.
Most of the food is found by diving individually, and the entire body is often under water. The neck and head are often moved back and forth like a snake, with the bird slowly rowing forwards to finally hit the prey quickly with its head. During the hunt, the bird sometimes swims with its neck and head above water, but the entire rest of the body remains below the surface of the water.
Small prey is swallowed underwater. Fish are speared with the beak and brought to the surface of the water. With a quick head movement, the fish is thrown onto the surface of the water, picked up again and swallowed head first. Occasionally, toss the fish in the air and catch it again before hitting the surface of the water. Large fish are occasionally taken to a resting place and eaten there.
Reproduction
Indian darters enter into a monogamous couple relationship that lasts for at least one reproductive period. They nest either individually or in loose colonies of up to ten nests. Often found in these colonies, other tree breeding waterfowl in India particularly common Mohrenscharben . A radius of several meters around the nest is defended against conspecifics. In contrast, they do not defend any food territory.
The male chooses the nesting site, occasionally choosing a previously used nesting site. The territory around the nest can be limited to the branch on which the nest is located or the entire tree in which it is incubated. One of the antagonistic behavior of Indian darter is that they point at an intruder with their beak closed. When it comes closer, the beak is opened slightly and the bird makes hissing noises. Non-breeding birds occasionally approach with open bills and spread wings, and they call very loudly. If the intruder comes even closer, they snap at him, but they do not aim at direct physical contact, the beak is only quickly closed near the head or neck. Only when the intruder is not deterred by this does the Indian darter, which is defending its territory, also peck at the neck or head of the intruder. The nest base is usually fresh branches, with the nest erected on top of it, up to 150 dry branches that are between 10 and 40 centimeters long are built. Some nests are so loose in their structure that the eggs are visible to an observer standing directly below the nest. The nesting material is mainly brought in by the male.
The Indian darter has a very variable breeding season, which depends on the local rainy season. In southern India and Sri Lanka, for example, the birds breed in the months of January to March, while northern Indian birds breed from July to September.
The clutch comprises three to six, usually three or four oval-elongated eggs. Both parent birds breed, the brood is taken with the first egg. The breeding season averages 28 days, the hatching of the young is asynchronous. Newly hatched chicks are initially naked. Nestlings are usually the size of their parent birds by four weeks of age. At this age, they also begin to climb out of the nest and occasionally even swim. Some of the young birds climb back into the nest, others stay on branches below the nest. At around fifty days old, they can fly short distances. The age at which nestlings usually fledge is not entirely certain. It is believed that they fledged at around sixty days.
Systematics
The Indian darter is part of the darter family (Anhingidae) and is closely related to the African darter (Anhinga rufa) and the Australian darter (Anhinga novaehollandiae). With these it was previously regarded as a single species, the Old World darter (Anhinga melanogaster). Genetic distance and morphological differences between the three species are of a similar order of magnitude as in typical cormorant species or gannet species , which also belong to the order Suliformes. A division of the species therefore seems justified based on the current status (2018).
The American darter differs more clearly from these three species, especially in the plumage due to the lack of the light cheek stripe.
No subspecies of the Indian darter are distinguished.
Others
The feathers of the Indian darter are worn on the hat as Roagaspitz in some traditional costumes, e.g. B. in the Berchtesgaden traditional costume .
literature
- J. Orta, EFJ Garcia, P. Boesman: Oriental Darter (Anhinga melanogaster). In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, E. de Juana (Eds.): Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona 2018. (accessed on www.hbw.com/ on July 7, 2018).
- H. Whistler: Popular Handbook of Indian Birds. Gurney and Jackson, London 1949. (Retrieved from archive.org/ on July 9, 2018).
- E. Baker: Anhinga melanogaster. The Indian Darter or Snake-bird. In: E. Baker (Ed.): The Fauna of British India Including Ceylon and Burma. 2nd Edition. Vol. 6, London 1929, pp. 282-283. (accessed on archive.org on July 15, 2018)
- PJ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds. Volume 1: Ratites to Ducks. Oxford University Press, Oxford 1990, ISBN 0-19-553068-3 .
Web links
- Anhinga melanogaster inthe IUCN Red List of Threatened Species 2018.1. Listed by: BirdLife International, 2016. Retrieved July 11, 2018.
- Videos, photos and sound recordings of Anhinga melanogaster in the Internet Bird Collection
Single receipts
- ↑ a b c d Handbook of the Birds of the World Alive. 2018.
- ^ WF Sinclair: Plumage of the Snake-bird 'Plotus melanogaster' . In: J. Bombay Nat. Hist. Soc. tape 12 , no. 4 , 1899, pp. 784 ( archive.org ).
- ↑ a b c R. Schodde, G. Kirway, R. Porter: Morphological differentiation and speciation among darters (Anhinga). In: Bulletin of the British Ornithologists' Club. vol. 132, No. 4, 2012, pp. 283-294.
- ↑ a b c d e Whistler, 1949, pp. 493-495.
- ↑ a b c d e Higgins, 1990, pp. 801-804.
- ↑ Baker, 1929, pp. 282-283.
- ^ List of bird names in the IOU IOC World Bird List