Hornbill
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Hornbill, male |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Rhyticeros undulatus | ||||||||||
| ( Shaw , 1811) |
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The furrows Hornvogel ( Rhyticeros undulatus ) is a species from the family of the hornbills , which is found in Southeast Asia. Like all hornbills, the furrow hornbill is a cave breeder. The female spends the breeding season in a breeding cave that is walled up except for a narrow gap. The male provides them and later the young birds with food. In contrast to many hornbills, the female only leaves the cave when the young birds fly out.
The stock situation of the furrow hornbird is given as Least Concern (not endangered).
Appearance
The furrow hornbill reaches a body length of 75 to 85 centimeters and is one of the larger hornbills. The male's beak accounts for an average of 20.2 centimeters, while the female's beak is significantly smaller with an average of 16.2 centimeters. The sexual dimorphism is pronounced in this species.
Characteristics of the male
The crown and the nape of the male are reddish brown. The face, forehead and front neck are white to cream in color. The body plumage and wings are black. The upper side of the body has a clearly noticeable metallic-green sheen. The control feathers are white without any black markings.
The beak is pale yellow with a dark brown-orange beak base and beak sheaths. The beak horn has a series of shallow furrows or cross grooves. The bare skin around the eye is red, the eyelids are pink. The bare throat patch is large , as in all species of the genus Rhyticeros . It is yellow in color with a blue and black mark. The eyes are dark red with a narrow pale yellow ring. The legs and feet are olive gray.
Features of the female and young birds
The adult females are smaller than the males and have black head and neck plumage. The featherless skin around the eye is flesh-colored, the bare throat patch is blue and, like the male, has blue-black markings in the center. The eyes are dark brown with a narrow blue border.
In the young birds, both sexes initially show a body plumage that resembles the male. Adolescent females molt into the dark cervical and head plumage at the age of seven to eight months, as is typical for adult females. The beak is white to pale yellow and the beak horn is not yet developed. The eyes are initially pale blue.
In not yet sexually mature birds, the beak horn begins to develop around six months of age. At the age of one year, the first transverse grooves appear in the rear third of the horn. Basically, one cross-mark develops per year of life. As an indicator of the age of a hornbill, however, the number of cross-grooves is only suitable until the beak has completely grown. After that, the number of cross-grooves caused by the wear and tear of the horn and beak no longer gives any indication of how many years a hornbill has already lived.
Possible confusion
The furrow hornbill is similar in appearance to the Sunday year bird . The range of the two species overlaps at least in India, Myanmar and Thailand and possibly even in Malaysia. The hornbill, however, is significantly larger. The Sunday year bird also lacks the black and blue markings on the sides of the bare throat patch. The wing shape of the two species also differs noticeably: in the Sunday year bird the hand wings are eight centimeters longer than the arm wings, while in the furrow hornbill the hand and arm wings are of the same length.
Distribution area and habitat
The distribution area of the furrow hornbird is not clearly documented due to confusion with the Sundajahrvogel. However, it is now largely certain that the range of this species extends from east India, across the south from Bhutan to Myanmar. The species is also found on some islands in the Mergui Archipelago . The range also includes Thailand, Cambodia, Vietnam, Laos and the Malay Peninsula. The species is also found on Sumatra, the Lingga and Batu Islands , Java, Bali and Borneo.
The furrow hornbird's habitat are large, evergreen primary forests. It colonizes mountain forests in particular and occurs regularly at altitudes of 1675 meters. In Myanmar, however, it has also been observed at altitudes of 2560 meters. It is also found in forests with selective logging.
Way of life
The furrow hornbill is a non-territorial, nomadic roaming hornbill species that is usually observed in pairs or groups of four to 14 individuals. In pairs or in groups, they roam an area of more than 100 square kilometers every day. They regularly fly at a height of 300 meters above the treetops. During his forays he also flies to islands that are not visible from the mainland coast. During these forays, he also flies over distances of up to 30 kilometers over non-forested areas and on Bali and Java, individual teams switch back and forth between the two islands every day.
The pair bond is maintained within the squads. Mated birds stay close to each other and occasionally switch to another group together. After the breeding season, they can be seen regularly in a small family group of three individuals. The parent birds are then accompanied by this year's young bird. Subadult birds predominantly live in their own flocks, where courtship feeding can often be observed.
Furrow hornbills find common resting places outside of the breeding season. In exceptional cases, up to 1000 individuals can spend the night at such a resting place spread over several trees. The birds arrive at these resting places at dusk and leave them with the first light of morning. Such rest areas are occasionally used for several years. The number of birds that can be found at such a resting place can vary greatly. The troops that gather at lunchtime resting places or at very rich fruit-bearing trees are smaller and usually do not exceed 40 individuals. Within the flock, the birds keep in contact with one another through their loud calls, the loud sound of their wings beating and the striking color of the throat pouch.
food
The hornbill is an extremely omnivorous species that uses a very wide range of food. The species shows a similar adaptability when searching for food: it uses the food available in the upper treetop area, where it hops from branch to branch, as well as on the ground. It uses its beak to peel bark from trees or to peel off capsule fruits. In his search for food, he alternates between eating fruit and hunting for animal food. Overall, however, animal proteins make up less than 10 percent of his diet.
Sugar-rich figs, which play a very dominant role in the diet of many Asian hornbills, also only make up 10 percent of the hornbill outside the breeding season. For hornbills breeding in Thailand, however, figs accounted for 57 percent of the diet. The stone fruits and berries of balsam trees and laurel plants play a major role in Borneo . In abundant fruit-bearing trees, several bird species regularly gather, including other, often smaller, hornbill species. Basically, the hornbill is less assertive towards these species than species that are more faithful to their location.
The prey that it eats include birds, which it can usually catch when they are breeding. It also eats bird eggs, tree frogs, bats, snakes, lizards, snails and insects such as large beetles. It also catches and eats spiders, millipedes and crabs. Like probably all hornbills, the hornbill does not depend on drinking. Hornbills kept in human care do not make use of the possibility to ingest water.
Reproduction
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Furrow hornbills are monogamous birds. Unlike a number of other hornbills, they are also not territorial and only defend the immediate area around their nest cavity. Mated birds often feed each other and also care for each other's plumage.
The breeding time depends on the respective distribution area. In Assam, India, hornbills breed from April to June when the climate is a little cooler. On Borneo they breed mainly in the period from January to May, when a particularly large number of trees bear fruit. The size of the clutch is only known from birds kept in human care. A female usually laid two, rarely only one or even three eggs there. Until now, however, only one young bird has ever fledged. The eggs are laid at intervals of several days, the hatching of the young birds is accordingly asynchronous. The oldest of the nestlings is larger and more assertive due to the hatching distance, so that only this one grows up.
Hornbills use natural tree hollows as nesting holes, usually between 18 and 26 meters above the ground. The entrance to the brood cavity is usually just large enough for the female to slip into. In a nest examined more closely, the entrance initially had a diameter of 13 centimeters. After it was walled up, only a 3.5 to 4 centimeter wide slot was open. The male does not take part in walling up the entrance. The female does this herself and uses her excrement, food waste, shavings and similar material from the nest cavity and occasionally even feathers. The breeding cavity is kept clean by the female by excreting through the gap and throwing away food residues through it. The young bird shows similar behavior later.
The male chokes the food he brings out of the throat and returns to the nest every 1.5 to four hours during the day. The female takes the food from him and even then passes it on to the young bird when the bird is already relatively mature.
The actual breeding season begins when the pair is increasingly in the area where it will later brood. Furrow hornbills are then also extremely happy to call. The entire nesting period lasts between 111 and 137 days. Of these, 13 to 14 days fall on the time that the female is already sitting in the cave but has not yet laid any eggs. The eggs are then incubated for about 40 days. The nestling period of the young bird lasts 90 days and the female usually leaves the cave with the young bird.
Hornbill and man
At least from the first half of the 20th century it is reported that the indigenous peoples in its area of distribution kept the hornbill again and again as domestic animals. To do this, however, it has to be caught as a young bird. Adult birds that are kept can become very aggressive towards the owner. In the Indian state of Assam , hornbills were shot and sold as a medicinal product as late as the 1920s.
literature
- W. Grummt , H. Strehlow (Ed.): Zoo animal keeping birds. Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1636-2 .
- Alan Kemp: The Hornbills - Bucerotiformes . Oxford University Press, Oxford 1995, ISBN 0-19-857729-X .
Web links
- Rhyticeros undulatus in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Retrieved on November 4 2016th
- Calls of the furrow hornbird on Xeno-Canto
Single receipts
- ↑ a b c d Kemp: The Hornbills - Bucerotiformes . P. 235.
- ↑ Rhyticeros undulatus in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Accessed November 1, 2016th
- ↑ a b Kemp: The Hornbills - Bucerotiformes . P. 233.
- ↑ Kemp: The Hornbills - Bucerotiformes . P. 232.
- ↑ Rhyticeros subruficollis in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Accessed November 1, 2016th
- ↑ a b Kemp: The Hornbills - Bucerotiformes . P. 234.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes . P. 236.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes . P. 237.
- ↑ Kemp: The Hornbills - Bucerotiformes . P. 238.