Crown eagle
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Crowned eagle ( Stephanoaetus coronatus ) |
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| Scientific name | ||||||||||||
| Stephanoaetus coronatus | ||||||||||||
| ( Linnaeus , 1766) |
The crowned eagle ( Stephanoaetus coronatus ) is one of the largest eagles in Africa and the only recent representative of the genus Stephanoaetus . It lives in the tropical forests and feeds mainly on medium-sized mammals , in the tropical rainforest mainly on monkeys. The conspicuously colored and very compact eagle is one of the physically strongest birds of prey and regularly prey on animals that considerably exceed its own weight. The species is considered harmless.
features
Crowned eagles are very compact. The wings are broad, quite short and rounded, the tail is relatively long. The feet are feathered down to the toes. Crowned eagles are 80–95 cm long and have a wingspan of 1.51 to 1.81 m. The female is significantly larger and heavier than the male. Females reach a weight of 3.2-4.7 kg, males weigh 2.7-4.1 kg. They owe their name to a crown of feathers that is set up when excited.
The plumage is dark gray-black on the upper side, the head is dark brown. Breast and belly are roughly dark spotted on a cream-colored to rust-red background; this spot goes towards the tail and on the legs into a strong black banding on a whitish background. The tail is broadly banded dark and light gray and has a narrow, light gray end band. The lower wing coverts are also cream or rust-colored, the hand and arm wings are white-gray with one ( hand wing ) or two ( arm wing ) dark ribbons and a wide dark end band. The toes and iris are yellow, the bill is dark gray.
Young birds differ significantly from colored individuals: They are pale gray on the upper side, all cover feathers are lightly edged. The head and the underside of the body are white and unspotted, only the fletching of the legs is slightly spotted. The pronounced dimorphism between adult and young crowned eagles presumably serves to protect the young birds. The independent young birds that invade territories are not regarded as serious competition by adult territorial owners due to this coloration and are therefore more likely not to be attacked as hard as their adult species.
distribution and habitat
The distribution area of the crowned eagle essentially covers Africa south of the Sahara and extends from Guinea and Senegal in the west to the east coast of South Africa . The distribution gap in West Africa corresponds to the lack of suitable forest habitats in this area. The occurrence in Ethiopia is geographically isolated .
The crowned eagle inhabits the tropical rainforest and subtropical forests . He colonizes savannahs and semi-deserts if there are sufficient trees in the form of forest islands or gallery forests .
Systematics
No subspecies are recognized for the species. The systematic special position as a separate genus was also confirmed by studies of the mitochondrial DNA . The crowned eagle is a well-defined taxon within the subfamily Aquilinae .
Food and way of hunting
Crowned eagles primarily hunt medium-sized mammals; Birds and reptiles only play a subordinate role in the food spectrum. Depending on the habitat, the food composition is very different. In the rainforests of West and Central Africa, monkeys are the main diet, their share of the total prey in the Taï National Park in the Ivory Coast was 49%, in several studies in Uganda it was over 80%. Living species as are captured mainly in groups monkeys , mangabey and colobus monkeys . In addition, a broad spectrum of vertebrates living in trees is hunted in the rainforest , including mongooses , pardle scooters , flying foxes , tree hyrax and palm squirrels , monitor lizards and hornbills . Especially be here on the floor Duckerantilopen captured, are also detected pouched rats and pangolins .
In more open landscapes, soil animals play a significantly larger role. In Kenya and South Africa , small antelopes and rock hyrax dominate the food spectrum with proportions of 60–80%, the proportion of monkeys here is below 10%.
The choice of prey identifies the crowned eagle as one of the most physically strong eagles ever. Most of the prey of the crowned eagle weighs between 1 and 6 kg, but the crown eagle regularly prey on monkeys and duiker antelopes weighing 8–12 kg . In Taï National Park , the average weight of prey animals was 5.7 kg, half the weight of the average prey weight of leopards , which are around 10 times as heavy as crown eagles. The largest prey animal recorded so far was a bushbuck with an estimated weight of around 30 kg.
The hunting methods have hardly been documented so far. There are reports of hunts from covered waiting, search flights in the treetop area as well as attacks from high circles. However, the hunt for tree-dwelling monkeys seems most often to consist of a combination of search flight and high seat. The hunting eagle flies through the treetops in good cover in search of groups of monkeys, sits down unnoticed in the direction of movement of a group and attacks from a short distance. Alternatively, it was observed in Zimbabwe how a crown eagle approached a group of monkeys in the treetops from behind near the ground, then pushed straight upwards and thus preyed on a monkey from below. At least occasionally the eagles hunt in pairs. The prey is killed with the extraordinarily strong feet and claws. If the victim is too big, it is dismantled before being transported and deposited in portions in the treetops.
Reproduction
The area is demarcated by frequent circling and calls all year round. During the courtship , the male in particular shows a wave-shaped show flight, which consists of a series of steep dives with subsequent steepening. During joint excursions, the male playfully encounters the female, who then throws herself on her back. Occasionally the eagles grab each other with their fangs and hit air wheels.
Both partners either build a new eyrie or repair the one from last year. The clumps are built on large trees, consist of branches and are padded with grass, leaves and moss. New clumps have a diameter of about 1.5 m and are about 0.5 m high, old clumps can reach a width of 2.5 m and a height of 3 m.
The clutch consists of 1–2 eggs, which are incubated for around 50 days, mainly by the female, while the male provides food. When two young birds hatch, the older one kills its younger sibling, this form of compulsory sibling killing is known as cainism . The nestling period is 90–125 days, males fly out about 10 days earlier than the heavier females. The young bird stays in the parents' territory for up to a year, so that they often only breed every other year. Crowned eagles are sexually mature when they are three to five years old. The life expectancy is about 15 years. No hikes are known.
Use of space and settlement density
Crowned eagles mate for life and often hunt in pairs. In optimal areas in the rainforest of West and Central Africa, the territories are 4–10 km² in size, so surprisingly small for a bird of this size. In the Taï National Park in Ivory Coast , 11 areas were found on 65 km², two nests that were occupied at the same time were only 1.1 km apart. In landscapes with little forest cover, the settlement density is considerably lower. In the Embu district in Kenya only 1 area was found on 378 km² in 1949–1953, in the Rhodes Matopos National Park in Zimbabwe 5 areas on 620 km², ie about 1 area on 125 km².
Danger
Due to its large distribution area of around 6.5 million km² and its relative abundance in many areas of this area, the crowned eagle is not considered threatened.
Others
A research group led by Scott McGraw from Ohio State University collected a total of 669 bones from prey on the Ivory Coast and examined them for typical prey marks of the crown eagle. These often leave deep holes in the bones and skulls of the captured animals. Such marks were often found on monkey skulls. Comparisons with the paleanthropological find of the so-called child of Taung , a 2.5 million year old skull of an Australopithecus africanus from Taung , South Africa , showed that it had injuries similar to those of the monkey skulls. Thus, the assumption made earlier that the approximately three-year-old Australopithecus child was killed by a large bird of prey is very likely.
swell
Individual evidence
- ↑ HRL Lerner and DP Mindell: Phylogeny of eagles, Old Word vultures and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics and Evolution 37, 2005, pp. 327-346.
- ^ A b c S. Shultz: Population density, breeding chronology and diet of Crowned Eagles "Stephanoaetus coronatus" in Taï National Park, Ivory Coast. Ibis 144, 2002, ISSN 0019-1019 , pp. 135-138.
- ^ JC Mitani, WJ Sanders, JS Lwanga, TL Windfelder: Predatory behavior of crowned hawk eagles ("Stephanoaetus coronatus") in Kibale National Park, Uganda. Behavioral ecology and sociobiology 49, 2001, ISSN 0340-5443 , pp. 187-195.
- ^ S. Shultz, R. Noe, W. Scott McGraw and RIM Dunbar: A community-level evaluation of the impact of prey behavioral and ecological characteristics on predator diet composition. Proc. R. Soc. Lond. B. 2003, doi : 10.1098 / rspb.2003.2626 .
- ^ LH Brown: Supplementary notes on the biology of the large birds of prey of the Embu District, Kenya. Ibis 97, 1955, pp. 38-64.
- ↑ V. Gargett: The Black Eagle. Acorn Books, Johannesburg 1990, ISBN 0-620-11915-2 , p. 264.
- ↑ Birds of prey hunted pre-humans. In: Adventure archeology. Cultures, people, monuments. Spectrum of Science Verl.-Ges., Heidelberg 2006,4, ISSN 1612-9954 , p. 8.
literature
- J. Ferguson-Lees, DA Christie: Raptors of the World. Christopher Helm, London 2001, ISBN 0-7136-8026-1 .
- V. Gargett: The Black Eagle. Acorn Books, Johannesburg 1990, ISBN 0-620-11915-2 .
- JC Mitani, WJ Sanders, JS Lwanga, TL Wind fields: Predatory behavior of crowned hawk eagles (“Stephanoaetus coronatus”) in Kibale National Park, Uganda. Behavioral ecology and sociobiology 49, 2001, ISSN 0340-5443 , pp. 187-195.
- S. Shultz: Population density, breeding chronology and diet of Crowned Eagles "Stephanoaetus coronatus" in Taï National Park, Ivory Coast. Ibis 144, 2002, ISSN 0019-1019 , pp. 135-138.
Web links
- Stephanoaetus coronatus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed October 13 of 2008.
- Videos, photos and sound recordings about Stephanoaetus coronatus in the Internet Bird Collection
