Crown Toko
| Crown Toko | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
.jpg)
Crown Toko, Kenya |
||||||||||
| Systematics | ||||||||||
|
||||||||||
| Scientific name | ||||||||||
| Tockus alboterminatus | ||||||||||
| ( Büttikofer , 1889) |
.jpg)
The crowned hornbill ( Tockus alboterminatus ) is an African bird art that the hornbills belongs (Bucerotidae). There are several subspecies that occur in eastern Africa from Ethiopia to South Africa. It is a territorial bird: couples occupy a territory and defend it against other species.
The stock situation of the crown toco was classified in the IUCN Red List of Threatened Species in 2016 as “ Least Concern (LC) ” = “not endangered”.
Appearance
The Kronentoko reaches a body length of 50 - 54 centimeters. Males weigh between 191 and 332 grams, females between 180 and 249 grams.
The male is dark soot-brown on the head, neck, back, wings and tail feathers. There is a white line drawing above the eye, and the cheeks also have pale gray dots. The control springs have white tips except for the outer pair and the middle pair. The feathers of the wing covers and the wing feathers are lined with pale brown. The throat and chest are gray-brown with gray dashes. The rest of the underside of the body is white. The beak is red to deep orange with a low horn. A yellow band runs along the base of the beak. The orbital ring and the undiluted throat patch are black. The eyes are yellow and the legs and feet are black.
The gender dimorphism is not very pronounced. The females correspond to the males in terms of plumage. However, they are a bit smaller, the horn is a bit shorter and less developed. The feathered throat patch is blue-green and a little more noticeable during the breeding season.
Young birds do not yet have a horn and have an orange-colored bill. They have white spots on the wing covers, the featherless throat spot is pale yellow and the eyes are gray. The color of the beak changes eight to ten weeks after they fledge to that of the adult birds. From the 16th week on, the horn gradually develops.
Calls
The voice of the Crown Toko are various, high and loud whistles. The contact sounds are a long, also loud kew , which excited crown tocoos utter in quick succession.
Both sexes call to indicate the boundaries of their territory. The beak is directed vertically upwards, the birds move rhythmically back and forth with the individual call syllables. They also call during the flight as well as during the night.
Possible confusion
.jpg)
There are several other species from the genus of the Tokios that occupy a similar habitat as the Crown Toko and that can be confused with it in field observations.
The Kronentoko differs from the Felsentoko by a shorter beak and its horn, from the Hemprich-Toko by its yellow eye and the almost completely black tail. The Hemprich toko also has a narrower beak.
The magpie toko has a similar plumage color to the crown toko and differs from it mainly in its beak, which is predominantly horn-colored. The gray Toko is also drawn whitish on the belly, but its body plumage is brown-gray, the beak has no red or orange tones. The Pale Beaked Toko is lighter in its overall appearance, the most noticeable distinguishing feature here is also the lighter beak.
Distribution, subspecies and habitat
The distribution area of the Crown Toco extends in East Africa from southern Kenya to Mozambique and the east of the Republic of South Africa . The distribution area extends over Zambia and the southeastern Congo in a strip to the west coast of Angola . There is an isolated population in southwest Ethiopia.
The three subspecies can be found in the following states:
- Angola Crown Toko ( Tockus alboterminatus alboterminatus ) / Büttikofer, 1889 : Angola
- East African crown togo ( Tockus alboterminatus geloensis ) / Neumann, 1905 : Angola , Ethiopia , Kenya , Uganda , Zambia ;
- South African crowned toko ( Tockus alboterminatus suahelicus ) / Neumann, 1905 : Somalia , Kenya , Mozambique , South Africa ;
The Kronentoko is a common inhabitant of forests near the coast as well as forests near rivers up to the African plateaus. But it is absent in evergreen moist forests of the lowlands, which represent the typical habitat of the magpie toko. The crown toco is also found in secondary forests. Its altitude distribution extends in some regions to altitudes of 3000 meters.
Way of life
Behaviors
The population density of the Crown Toco varies with the conditions of its respective distribution area. It is dependent on wooded habitats, which, however, are often fragmented in its range. Usually a couple occupies a territory with a size of three to five square kilometers that can overlap with the territories of other Crowned Tokos. The area must have a contiguous forest area of at least 7 hectares in order to offer suitable living conditions for Crown Tocos. In East Africa, a total of 28 breeding pairs of Crowned Toco have been counted in a 440 hectare forest near the river. In these districts he lives either in pairs or in small family groups of up to seven individuals. Crown tookos are usually resident birds. However, during droughts or when the food supply decreases seasonally, migratory movements occur, in which crown tocoos also stay outside their typical habitat. On these hikes, they can form larger groups. In the Cape Province of South Africa, troops of up to eighty crowned tokos have been counted.
It is typical for Crown Tokos that they rest on long, thin branches that have no foliage in their immediate vicinity. A territory has up to six such resting places, which are regularly visited by the Crown Toko.
Food and foraging
.jpg)
The diet consists of insects that are often caught in flight, small mammals, lizards and frogs, fruits and seeds. Occasionally it also eats the eggs and nestlings of pigeons or smaller bird species such as the forest weaver ( Ploceus bicolor ) or the gray-breasted paradise flycatcher ( Terpsiphone viridis ). Fruits play a bigger role in the food spectrum, especially during the dry season. Crown tookos also eat the fruits and seeds of introduced plants such as the fruits of the oil palm , blackberries, corn, peanuts and bananas. It releases larger indigestible food residues such as seeds in the form of spits .
He looks for his food mainly in the foliage of trees. It comes to the ground comparatively rarely. He typically looks for food there when the food supply is generally sparse.
Reproduction
The crown toco nests mainly in natural tree hollows. Suitable breeding caves are usually used for several years. Crowned tokos always return to their ancestral nesting cave outside of the breeding season . The frequency of visits increases before the start of the breeding season. The female then begins to seal crevices and cracks in the brood cavity, and the male begins courtship feeding of the female. Young birds from the previous breeding season are then driven out of the area. In South Africa the beginning of the breeding season coincides with the onset of the rainy season, in other parts of the distribution area the breeding season is not tied to a specific season.
The tree species whose natural tree cavities are used by the Crown Toko include the African baobab , ana tree , coral trees and trees of the genus Schotia . Hollow trees with a diameter of 20 centimeters and an entrance that is no more than 6.5 by 4.8 centimeters are sufficient to be suitable for the breeding business of the crown toco.
_male.jpg)
The female uses her feces, sticky fruit and food, and some of the nesting material to seal the cave entrance and crevices and cracks. The male brings material that is used to pad the nest cavity. A large proportion of it is made up of pieces of beef, but it also brings flowers and snail shells.
The female lays two to five eggs with a laying interval of at least two days. However, the laying interval between the penultimate and last egg of the clutch is usually four days. The female starts brooding as soon as the first egg is deposited and goes through the molt while sitting on the eggs. The male returns to the breeding cave between forty and fifty times a day and brings food to the breeding cave, which he offers to the female through the remaining open gap in the breeding caves.
The nestlings hatch asynchronously due to the laying distance. The female leaves the brood cavity 25 to 30 days after the last of the nestlings has hatched. It then stayed in the brood cavity for an average of 61 to 69 days. Her plumage has grown back in the meantime and she immediately takes part in the feeding of the nestlings, who seal the nesting cave entrance independently and only leave the nesting cave on average 15 days after the female parent bird. They can then already fly well and do not return to the brood cavity.
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 .
- Gordon Lindsay Maclean - Robert's Birds of South Africa. 6th edition. ISBN 0620175834 .
Web links
- Lophoceros alboterminatus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 30 of 2009.
- Videos, photos and sound recordings of Tockus alboterminatus in the Internet Bird Collection
- The Crown Toco's calls to Xeno-Canto
Single receipts
- ↑ Grummt, H. Strehlow (Ed.): Zoo animal keeping birds . P. 538
- ↑ Lophoceros alboterminatus in the endangered Red List species the IUCN 2016 Posted by: BirdLife International, 2016. Retrieved on 3 October 2017th
- ↑ a b c d e f Kemp: The Hornbills - Bucerotiformes . P. 112.
- ↑ Kemp: The Hornbills - Bucerotiformes . P. 110.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes . P. 111.
- ↑ Calls of the Crown Toco on Xeno-Canto , accessed October 1, 2016
- ↑ a b c d e Kemp: The Hornbills - Bucerotiformes . P. 113.
- ↑ Kemp: The Hornbills - Bucerotiformes . P. 114.