Gray-cheeked hornbill
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Gray-cheeked hornbill |
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| Bycanistes subcylindricus | ||||||||||||
| ( Sclater , 1871) |
The gray-cheeked hornbill ( Bycanistes subcylindricus , Syn . : Ceratogymna subcylindricica ) is a species of the hornbill family . Its distribution area is in sub-Saharan Africa . Two subspecies are distinguished in the large distribution area.
Like all hornbills, the gray-cheeked hornbill is a cave breeder. The female walled up the brood cavity except for a narrow gap. During this time, the male first supplies them and later also the young birds with food.
The population of the gray-cheeked hornbill was classified in the IUCN Red List of Threatened Species in 2016 as “ Least Concern (LC) ” = “not endangered”.
features
The gray-cheeked hornbill reaches a body length of 60 to 70 centimeters and is therefore one of the larger species among the African throat pouch hornbills. The male of the nominate form has an average of 24 centimeters for the tail feathers and 23 centimeters for the females. The beak in the males of the nominate form has a length between 14 and 16.6 centimeters. The female's beak remains slightly smaller and is 10 to 13.3 centimeters long. The gender dimorphism is only slightly pronounced.
Appearance of the males
In the male, the head, neck, front chest and back are glossy black. The feathers on the cheeks and the base of the beak are lined with gray. The back, the upper tail and lower tail, as well as the belly and thighs are white. The chest is black. The middle pair of the control springs is black, the rest are white with a wide black central band. The arm wings and inner hand wings are white with a black base. The feathers of the large wing-coverts have white tips, the other feathers of the wing-coverts are black.
The beak and the beak tip are dark brown with a large cream colored spot on the front half of the beak tip. The beak attachment is comparatively high and has the shape of an inverted chopping knife. The featherless skin around the eyes is grayish flesh-colored. The eyes are red, the legs and feet are black.
Appearance of females and fledglings
The females resemble the males in their plumage, but they stay smaller and have a less developed beak attachment. The featherless skin around the eyes is pale pink, the eyes are brown.
Fledglings have plumage that is similar to that of adult birds. The beak is smaller than that of the adult birds and darker. The beak attachment has not yet been developed for them. At the base of the beak, feathers still have brown edges. Only at the age of 10 months does it change to gray in the adult birds. The eyes are gray. Males already have a significantly larger beak than the females at the time they fled.
Possible confusion
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The range of the gray-cheeked hornbill overlaps in parts with that of the brown -cheeked hornbird and the screechhornbird .
The brown-cheeked hornbill has a similar body size and is very similar to the gray-cheeked hornbill in terms of plumage. However, it has a cream-colored beak and a cream-colored beak tip.
The hornbill is significantly smaller and also has a significantly smaller beak and beak attachment. The control springs are black with white tips.
Distribution area and habitat
The gray-cheeked hornbill has a disjoint distribution area in northern sub-Saharan Africa.
- The nominate form B. s. subcylindricus occurs on the Ivory Coast, Ghana, Togo, Benin and Nigeria.
- The subspecies B. s. subquadratus occurs in Cameroon, the Central African Republic, the south of Sudan and Chad, in Zaire, Uganda, in the west of Kenya, in Tanzania as well as Rwanda and Burundi. There is also an isolated population in northeastern Angola.
The habitat of the gray-cheeked hornbill are evergreen forests. It is particularly common in pristine forests, but also colonizes secondary forests, plantations and forest edges. It can also be observed in savannahs when there are forests or sparse forest areas nearby. Its altitude distribution extends up to 2600 meters. The population density in primary forest can be up to 49 individuals per square kilometer. In forests with partial or selective logging, the population density drops to seven birds per square kilometer.
Way of life
Couples formed once exist for several years. However, they join troops at rich feeding places, which can comprise between 20 and 50 individuals. In addition, flocks of sub-adult birds form, which roam a larger area in search of food. Gray-cheeked hornbills also frequently seek out familiar resting places. This can occasionally lead to a gathering of larger groups.
food
Like almost all hornbills, the gray-cheeked hornbill is omnivorous. However, it covers most of its nutritional needs with fruits. The foraging usually takes place in pairs.
When examining gray-cheeked hornbills in Uganda, 91 percent of his nutritional needs were covered with fruits. Of this, figs accounted for 51 percent. He also eats various capsule and stone fruits . The fruits are usually no larger than a pea or an olive. Larger fruits with a diameter of up to 6 centimeters are only eaten occasionally. In Uganda, fruits from 67 plant species from 26 families and 38 genera have been found. In addition to figs, the fruits of hackberry trees , cola trees , cordias , ebony trees , dragon trees , lychnodiscus , Maesopsis eminii and mulberries are used . It also eats fig species introduced in Africa as well as papayas, which are also not native to its area of distribution . The gray-cheeked hornbill finds this food predominantly in the treetop area, where it picks fruit directly from the branches.
Animal protein also plays a major role in his diet. It mainly eats insects such as termites, beetles, moths, bees, caterpillars, cockroaches, praying mantises and crickets. But it also eats small birds and their nestlings, bats, lizards, snails and centipedes. In the hunt for animal protein, the gray-cheeked hornbill occasionally comes to the ground. Animal protein plays a larger role in nutrition, especially when rearing young birds.
Reproduction
The gray-cheeked hornbill is monogamous, but does not defend a breeding area, only the immediate area of the breeding cave. Occupied breeding caves are sometimes only 40 meters apart. The clutch usually comprises two eggs. Gray-cheeked hornbills that are cared for in human care breed for the first time at an age of 3 years. In captivity, gray-cheeked hornbills can live up to 32 years.
At the beginning of the breeding season, mutual feathering and courtship feeding can be observed, in which the male offers food to the female. Increased inspection of suitable breeding caves is also typical. Before breeding begins, both sexes show behavior in which the breeding cavity is sealed. The male is also involved in this act. The male also brings saliva clods of earth to the entrance to the breeding cave in his throat. The female is mainly busy in the morning hours with sealing the brood cavity. To do this, it slips into the brood cavity and blocks it from the inside with rapid lateral movements of the beak. If you do not have a lump of earth available, you will also block your own excrement.
A natural tree cavity is usually used as a breeding cave. This is usually 9 to 30 meters above the ground. Where there are many very large trees, the density of the nest caves can be very large. In Uganda, up to 11 occupied breeding caves were found in undisturbed primary forest.
The female begins to breed when the first egg is deposited. The nestlings hatch accordingly asynchronously. Usually only the older nestling will grow up. The younger one usually starves to death. The male brings food to the brood cavity. In nests observed in Uganda, the male returned to the brood cavity every hour. He choked up the swallowed food at the nest cavity and passed it on to the female. Over 200 pea-sized fruits or two to 17 olive-sized fruits were counted per visit. For gray-cheeked hornbills kept in captivity, what was eaten by the breeding pair during the breeding season and later by the breeding pair and the offspring was weighed. While before the breeding season the couple kept eating 560 grams of food a day, which consisted of 70 percent fruit and 30 percent animal protein, during the breeding season the proportion of animal protein doubled to 320 grams, while the fruit proportion remained constant at 420 grams. During the time that the nestlings were being fed, the hornbills ate 930 grams of fruit and 620 grams of animal protein.
Trivia
During the directorate of Heinz-Georg Klös in 1977 the Berlin Zoo succeeded in first breeding the gray-cheeked hornbill in Germany.
literature
- Mark Cocker, David Tipling: Birds and People. Jonathan Cape, London 2013, ISBN 978-0-224-08174-0 .
- 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
- Bycanistes subcylindricus inthe IUCN Red List of Threatened Species 2016.10. Posted by: BirdLife International, 2016. Retrieved December 10, 2016.
Single receipts
- ↑ Kemp: The Hornbills - Bucerotiformes. P. 244.
- ↑ Bycanistes subcylindricus in the IUCN Red List of Threatened Species 2016.10. Posted by: BirdLife International, 2016. Retrieved October 3, 2017.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes. P. 252.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes . P. 253.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes. P. 254.
- ↑ a b c d Kemp: The Hornbills - Bucerotiformes . P. 255.
- ↑ a b Kemp: The Hornbills - Bucerotiformes. P. 256.
- ↑ World and German first breeding at Zootierliste.de