Jackson-Toko
| Jackson-Toko | ||||||||||
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Jackson-Toko, male, Kenya |
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| Systematics | ||||||||||
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| Tockus jacksoni | ||||||||||
| ( Ogilvie-Grant , 1891) |
The Jackson-Toko ( Tockus jacksoni ) is a bird art that the hornbills belongs (Bucerotidae) and in the western sub-Saharan Africa occur. Like all species of the genus Tokos , it is a cave breeder. The female walls herself in during the breeding season and is only supplied with food by the male through a narrow gap that she leaves open.
The Jackson Toko has long been classified as a subspecies of the Ceiling Toko , from which it differs, among other things, by the different color of the beak in the male and the white markings on the wings. Meanwhile, the species status of the Jackson toko is generally recognized.
The stock situation of the Jackson Toko was classified in the IUCN Red List of Threatened Species in 2016 as “ Least Concern (LC) ” = “not endangered”.
features
The Jackson Toko reaches a body length of a little less than 35 centimeters and is one of the small Toko species. The sexual dimorphism is limited to a different beak color, the females are also slightly smaller. The beak in the males is between 7.3 and 8.7 inches long. In females, it measures between 6.5 and 7.3 centimeters. The tail feathers account for an average of 20.6 centimeters in the male and up to 17.8 centimeters in the females.
male
The males have a black crown. The sides of the head and the neck are white, the ear covers are dashed gray. The middle of the back and the underside of the body are also white. The back, the rump and the four central control springs are black. The outer control springs are white and only black at their base.
The wings are conspicuously spotted with white. The beak has a narrow ridge over the entire length of the beak and is orange and has a lower proportion of yellow than the ceiling toko. The featherless orbital ring is black, the bare throat skin is flesh-colored. The eyes are brown, the feet and legs are black.
Females and young birds
The females correspond to the males in the body plumage. However, the beak is black overall. In most females, the beak ridge ends in half of the upper beak. Young birds are similar to the adult female, but the beak is significantly smaller.
voice
The calls of the Jackson Toko are cackling sounds that he utters individually or in series. They are harsher than those of the ceiling toko.
Possible confusion
The distribution area of the very similar blanket toko borders on that of the Jackson toko and overlaps in the east of Lake Turkana . The ceiling toko is slightly larger than the Jackson toko and the most striking feature of the males is a red and yellow beak. The adult blanket tokos also lack the white markings on the wings, only subadult individuals have this, which long led to the Jackson toko being classified as a subspecies of the blanket toko.
Other Toko species, such as the red-billed Toko of the same size, also occur in the distribution area of the Jackson Toko, also have white markings on their wings. However, his beak is red. It also differs from the Eastern Yellow-Beaked Toko in its beak color.
The Kronentoko , which is also common in the Jackson Toko, is significantly larger with a body length of 50 to 54 centimeters and has a soot-brown head.
distribution and habitat
The distribution area of the Jackson Toko is northeast Uganda and northeast Kenya.
Its habitat is semi-arid savannahs with sparse trees and bushes. The white rump song hawk ( Melierax poliopterus ) is one of the predators in its habitat .
Food and diet
The Jackson toko's diet consists of insects, fruits, and seeds that they commonly find on the ground. The insects that it eats include grasshoppers, praying mantises, beetles and their larvae, crickets and cicadas. The berries of the plant genera Cissus and Commiphora also play a role in nutrition. Occasionally it also eats snails, mice, nestlings of other bird species, lizards and tree frogs.
Reproduction
The riveting cycle of the Jackson Todko has a duration of 80 to 82 days. The nestling time of the young birds accounts for 47 to 50 days. The breeding season falls from February to March. Compared to other types of tokos, the Jackson toko clutch with two eggs is unusually small.
Jackson tokos breed in tree hollows and occasionally use abandoned breeding holes of the woodpecker for their breeding business. Typical nesting trees are Vachellia tortilis and palm trees. A cave entrance with a diameter of 5 centimeters is enough for the relatively small Toko. At the beginning of the brood it is walled up by the female from the inside except for a narrow gap. It moults in the brood cavity and is supplied with food by the male while it is in the brood cavity.
The laying interval is probably two to four days. The nestlings hatch asynchronously according to this laying distance. The female leaves the brood cavity when the nestlings are around 21 to 28 days old. The nestlings then wall up the brood cavity up to a narrow gap. From then on, both parent birds take part in feeding the nestlings. The nestlings leave the nest about 22 to 28 days after the females have left the brood cavity. In captive Jackson tokos, secondary litters occurred immediately after the nestlings of the first brood fledged.
attitude
Like many Toko species, Jackson Tokos are also kept more frequently in zoological gardens. A Jackson Toko already bred in captivity reached an age of 11.9 years there.
Dedication names
The Jackson Toko is named in honor of Frederick John Jackson (1859–1929), a British administrative employee of the Imperial British East Africa Company , who later became a colonial official, explorer and scientist. Jackson explored the East African coast in what is now Kenya between 1884 and 1888. This was followed by a joint research trip with Arthur Henry Neumann on behalf of the Imperial British East Africa Company in 1889 to the region between Mombasa and Lake Victoria , which at the time was largely undeveloped. As a colonial administrator he administered the British East African Protectorate from 1907 to 1911 and Uganda from 1911 to 1917. Jackson had been a member of the British Ornithologists' Union since 1888 and brought back numerous specimen copies from his travels and published repeatedly in the ornithological journal Ibis . At the time of his death he was working on a work on the avifauna of East Africa.
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 .
- Theo Pagel , Bernd Marcordes: Exotic soft-eaters. Eugen Ulmer Verlag, Stuttgart 2011, ISBN 978-3-8001-5192-9 .
Web links
- Tockus jacksoni in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Retrieved on October 7 2016th
Single receipts
- ↑ Tockus jacksoni in the endangered Red List species the IUCN 2016 Posted by: BirdLife International, 2016. Retrieved on 3 October 2017th
- ↑ a b c d Kemp: The Hornbills - Bucerotiformes . P. 143.
- ↑ Pagel, Marcordes: Exotic soft-eaters . P. 82.
- ^ Voice of the Ceiling Toko on Xeno-Canto , accessed October 6, 2016.
- ↑ a b c Kemp: The Hornbills - Bucerotiformes . P. 142.
- ↑ a b c d Kemp: The Hornbills - Bucerotiformes. P. 144.
- ↑ Bo Beolens, Michael Watkins: Whose Bird? Men and Women Commemorated in the Common Names of Birds . Christopher Helm, London 2003, ISBN 0-7136-6647-1 , pp. 205 .