Juggler (bird)
| Juggler | ||||||||||
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Juggler male ( Terathopius ecaudatus ) |
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| Systematics | ||||||||||
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| Scientific name of the genus | ||||||||||
| Terathopius | ||||||||||
| Lesson , 1830 | ||||||||||
| Scientific name of the species | ||||||||||
| Terathopius ecaudatus | ||||||||||
| ( Daudin , 1800) |
The juggler ( Terathopius ecaudatus ) is a bird of prey from the subfamily of the short-toed eagle (Circaetinae), which occurs in large parts of sub-Saharan Africa and inhabits open or semi-open savannah landscapes. The juggler feeds mostly on small to medium-sized birds and mammals that he hunts, but also on carrion. He is noticeable for his extended, relatively low, "rocking" search flights, in which he holds the wings in a deep V and rocks back and forth to the side. In addition, the acrobatic parade is quite spectacular.
description
The juggler is a relatively large bird of prey, which is similar in body to the Old World vulture , but is related to the short-toed eagle. Its body length is between 55 and 70 cm, with the tail being extremely short, which is also indicated by the epithet of the scientific name ( ecaudatus = tailless). In adult birds, the feet protrude beyond the tail in flight. The wings, with which it reaches a span of 168 to 190 cm, are exceptionally long and with 25 arm wings have most of all birds of prey. The rear edges of the arm wings form a large arch, while the hand wing is relatively short and pointed. The head looks large, with long nape plumage that can be raised to form a hood. The weight is between 1820 and 2950 g.
The sexes are similar, but are relatively easy to distinguish due to the gray armwings of the females. Females are also on average 6% larger than males. The youth dress is mostly brown. Subadult birds change into darker and darker clothes for eight years before they are colored. There is a beige morph in which the back and the control feathers in the adult dress are cream-colored rather than maroon. This morph seems to be common in arid regions. However, their share is no more than 7%.
In adult birds, the front beak is yellow with a black tip; The base of the beak and the wax skin are red like a featherless area around the eye. The iris is - as in all clothes - brown. The plumage is predominantly black. The shoulder plumage is gray and, when it is newly moulted, shows whitish edges. The back, rump, tail feathers and under tail coverts are maroon. In males the large arm covers and arm wings are black, in females the former are dark brown, the latter, however, gray with a broad, black end band. Legs and feet are red in both sexes.
Young birds are long-tailed and predominantly brown feathered with a visibly lightened head and reddish seams on the rest of the upper side. The wax skin is greenish-blue, the feet whitish in color. In the clothes that follow, subadult birds become darker and already hint at the color areas of adult birds. The face, legs and feet initially turn orange before they gradually take on the bright red coloration of adult birds.
When taking off, the juggler starts with unusually fast flaps of the wings and then falls into the typical juggling 50-60 km / h fast glider, in which he holds the wings in a deep V and rocks back and forth. It hardly flaps its wings, but it is also dependent on a certain amount of thermals . In the early morning, late afternoon or in wet and cold weather, jugglers usually sit on trees for a long time. They typically hold themselves very upright.
voice
The juggler is usually not very shouting. Sounds can be heard especially during courtship but also in the event of danger or disputes. The main calls are a harsh schaaa-ah or a barking kau-or . They can be heard both from sitting and courting birds, but also from jugglers who hunt prey from other species. They are loud and carry far and are usually brought forward with the head thrown back. In their highest intensity they are reminiscent of the calls of the fish eagle .
distribution
The distribution area of the juggler extends over large parts of the Afrotropis , where it is missing or extinct in the rainforest belt, on Madagascar, at the tip of the Horn of Africa and in large parts of the south. In the north it extends from southern Mauritania via Senegal and Gambia , through southern Mali and Guinea eastwards to central Sudan , to Ethiopia and western Somalia . The southern border runs through Namibia , Botswana and northern and northeastern South Africa . It is unclear whether the deposits in southwestern Saudi Arabia and Yemen still exist.
habitat
The juggler settles in open and semi-open landscapes such as grasslands , dry and thorn-bush savannahs through to light dry forest . In contrast, it is absent in closed forests and wetlands, but can also be observed on its extended foraging flights over these or other habitats . The altitude distribution is between sea level and 4500 m, but mostly below 3000 m.
nutrition
The food spectrum of the juggler is very diverse. On the one hand, it actively hunts prey such as mammals and birds, but also searches specifically for carrion and also eats bird eggs, insects such as termites or grasshoppers, dead fish or crabs.
The size of the prey animals can be very different. It ranges from shrews or small birds to small antelopes or bustards , dikdiks , eagle owls and hornbills . In terms of weight, it ranges up to over 1.2 kg in birds and 4 kg in mammals. Mammals and birds make up between 70 and 90% of the prey. In contrast to other short-toed eagles, the proportion of reptiles in the prey is quite small. The spectrum here ranges from small lizards to snakes and monitor lizards.
The juggler can spend up to eight or nine hours a day on his food flights, whereby he can fly an area of 55 to 200 km² or cover a distance of between 300 and 500 km. It searches the landscape from a height of around 50 m, sometimes flies back a little and hits the ground in tight spirals to grab prey or examine carrion. It is not uncommon for him to be the first to arrive at a carcass or pick up freshly dead traffic victims from the streets. Prey is usually killed on the ground after the juggler has dropped to the ground with half-open wings or has slid down with open wings. Occasionally it is also taken out of thin air, as documented in one case with a white-winged tern , or it is hunted from other birds. Insects are often caught on foot.
In places with abundant food supply, such as fire or floodplains, as well as in termite burrows with swarming animals, between 40 and 50 or more jugglers can sometimes gather. Juvenile or subadult birds are more likely to be found on larger carcasses than adult individuals.
Reproduction
The breeding season in West Africa is between September and May, in East Africa over the whole year and in southern Africa from December to August. The eye-catching parade with rocking, overturning and swooping flight maneuvers takes place with loud wing beats that can still be heard a long way away.
The nest, which is between 40 and 150 cm wide and 30 to 80 cm high, is built from twigs and greened within five to six weeks. It stands between 7 and 26 m high in widely spreading forks of large trees such as Senegalia nigrescens and other acacia relatives, Ficus sycomorus or Diospyros mespiliformis . Occasionally it is built on nests of other species of birds and often near river courses. It is often reused over several years and grows in size over time. Usually a new nest is built every three years.
The clutch consists of a single, dirty white egg, 79 mm × 63 mm in size, which is incubated by both partners for between 52 and 59 days. The nestling time varies greatly, it can be between 93 and 194 days, but usually lasts between 110 and 112 days. The young birds are dependent on their parents for up to four months after they have fled. Both parents take part in the rearing of the young and are supported by other adult or subadult birds.
Up to a third of the broods fail in the course of the nestling period if the nests are cleared out by predators without being guarded during the long foraging flights of the adult birds .
hikes
Territory pairs are mostly resident birds . Young birds that have been driven out of the family group, however, sometimes cover long distances and live nomadically. In the south-west and east of Africa larger clusters are sometimes formed. Birds from western Africa often move north during the rainy season between July and September, birds from eastern Africa tend to move along the equator. The species was found to be a stray visitor in Spain, Tunisia, Egypt, Cyprus, Israel, Palestine and Iraq.
Inventory development
The juggler is mostly rare or absent-minded, but can be quite widespread locally, such as in the Masai Mara . In large parts of the distribution area, the population has been subject to relatively strong declines of up to 50% since the 1970s, the causes of which are still ongoing, so that the species is classified as potentially threatened (“near threatened”) and sometimes even the criteria for one endangered species (“vulnerable”) met. The population losses have been particularly large since the 1940s in South Africa, where the species has declined by up to 80%. Originally the population in the Transvaal comprised 2,000–2500 breeding pairs, in the early 1980s there were only 420–470 pairs. However, that number then rose back to around 600 couples in the 1990s.
The world population is believed to be between 10,000 and 100,000 individuals. The numbers are declining in the Ivory Coast , Nigeria , Sudan and Somalia, parts of Kenya , Tanzania and Zimbabwe as well as in Namibia, Botswana and parts of South Africa. In contrast, there were increases in Masai Mara , in northern South Africa and possibly in Uganda . There has been no evidence from the southwest of Arabia since 1999.
In many places, the main source of danger is direct persecution by large commercial farmers who lay out poisoned carcasses. But this also occasionally occurs in the context of smaller, arable tribal societies . Other causes include increasing pesticide pollution, habitat destruction, disruption from the expansion of human settlements, and catching for international trade.
literature
- James Ferguson-Lees , David A. Christie: Raptors of the World. Helm Identification Guides, Christopher Helm, London 2001, ISBN 0-7136-8026-1 .
- AC Kemp, Jr., Guy Kirwan, David Christie: Bateleur (Terathopius ecaudatus) (1994/2013), in: J. del Hoyo, A. Elliott, J. Sargatal, AD Christie, E. de Juana (eds.): Handbook of the Birds of the World Alive , Lynx Edicions, Barcelona 2014
Web links
- Terathopius ecaudatus in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Accessed January 4, 2015.
- xeno-canto: sound recordings - jugglers ( Terathopius ecaudatus )
- Videos, photos and sound recordings on Terathopius ecaudatus in the Internet Bird Collection