Colours of Wildlife: Bateleur
Created | Updated Dec 1, 2013
Bateleur
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
This is one of Africa's most striking birds, a Bateleur, Terathopius ecaudatus. Though it might be hard to tell, it is actually a kind of eagle! It has the boldest colours of any African eagle. Males and females look similar, but the female has a patch of light feathers visible in her folded wing. In flight, the underside of the female's wing is almost completely white with just a thin black margin, while the male has a much broader black band along the wing's trailing edge. Juvenile bateleurs are often not recognized since they look very different, being plain brown all over. They can be identified by their shape though, having the typical long wings, short body and shaggy crest. Bateleurs achieve a head-to-tail length of 70 cm/28", a wingspan of 186 cm/6'1", and a weight of 3 kg/6.6 lbs.
The name 'Bateleur' comes from French and means street performer: tumbler, acrobat, juggler or tightrope walker. The latter perhaps comes closest to explaining the name. Bateleurs have a very unique flight profile, with long wings and a very short tail, the feet extending beyond the tail. They are fast and maneuverable in flight, and while in level flight they rock their bodies from side to side while their wings stay even. This might suggest a tightrope walker with a long balancing pole, swaying slightly from side to side.
The scientific name 'Terathopius' isn't quite proper Greek but might mean 'marvelous face', while 'ecaudatus' means 'without a tail'. This refers to the short tail … whether flying or perching, this eagle always seems very compact-bodied and almost tailless.
Against its black body and head plumage, the bateleur's red face is very vivid. Actually the colour can change, almost like a mood ring! When they are aggressive or excited, bateleurs' faces turn deep red; when they are perched or taking a bath, and relaxed, their faces can lighten to pale pink or yellowish. After death a bateleur's face and legs also fade to yellow.
Bateleurs are also poseurs! They like to sunbathe, lifting their short bodies high on their legs and spreading their wings sideways, so the sun can hit their chests, bellies and the undersides of their wings. Another pose they often adopt is a threatening one: they will puff up their crests and the loose feathers of their bodies and backs, lift their wings and spread them partially. They may do this as part of a mating dance on the ground also; this dance also involves poses where the male bateleur drops his head low to show the chestnut patch of feathers on his upper back.
Probably the closest relatives of bateleurs are the snake eagles. Those are all rather drably coloured, though, and have fairly normal-length tails. The bateleur's short tail is an adaptation that makes it more maneuverable in flight. Bateleurs are opportunists, their 'shtick' being to spot and get to prey items before anything else. They fly fast and low, covering great distances – as much as 500 km/310 miles – on each daily hunt. They spend as much as 80% of the day on the wing, but make use of updrafts and air currents, flapping their wings but rarely. Often they will scavenge; getting to a carcass quickly will allow them to grab a few bites before the vultures arrive and drive them off. But bateleurs do hunt their own prey as well. Because of their speed, they use the element of surprise a lot. They have very sharp vision, spotting their quarry from afar, then gaining speed to swoop in for the strike. They often take birds that have been momentarily distracted; a roller that has just spotted prey and swoops down to catch it, might find itself in the claws of a bateleur a fraction of a second later! Bateleurs will catch small mammals as well, and, like their relatives, snakes. Although most prey is taken on the ground, they sometimes catch birds on the wing. They also sometimes act as pirates to other eagles, swooping and diving at them to make them drop their prey, which they will then snatch up. They have also been recorded eating eggs of other birds. Strangely enough, they've even been seen catching fish! They are not able to snatch them out of the water like fish eagles but take them when they get stranded in rapidly drying, shallow pools. Lastly, they are not averse to catching tiny prey items like swarming winged termites.
Courting bateleurs perform spectacular aerial displays! The male dives down towards the female, who rolls onto her back (while still in the air, mind you) and holds her claws up to him, which he might then grab so the two can 'hurtle' through the air. Otherwise the male may not grab her, but let his legs dangle towards her while he continues to fly. He gives a far-carrying barking call, also claps his wings with an audible noise, and executes rapid sideways rolls. Sometimes two male bateleurs will join in this flight in pursuit of the female, but she will accept only one. The two will then remain together for life.
For their nests bateleurs need tall trees. They build their nests about 10-15 m/30'-50' above the ground, but not at the top of the tree, instead seeking a spot inside the canopy where higher leafy branches can provide some shade. They can use baobab trees but seem to prefer the shade and protection of thorn trees. They usually build their own nests but sometimes take over old nests of other eagles. The eggs can be laid anytime during summer and autumn. The babies are mostly reared during the cool, dry winter. The female usually lays just a single, large egg. The male and female both perform incubation duty. The male is more aggressive in defense of the nest, performing threat displays or dive-bombing predators. Sometimes older children will help the parents at the nest and with feeding the chicks. Bateleurs are very sensitive to disturbances at the nest, and acts such as setting up a hide or installing photographic equipment near the nest often cause them to abandon their nests. This has made it a bit difficult to study their breeding behavior, and photographs of chicks are very rare.
The big egg needs a long incubation period, up to 59 days – the longest for any African eagle. The nestling also develops slowly, the primary feathers of the wing, especially, taking long to attain full length. It starts flapping its wings at five weeks, eats by itself at six weeks, and at nine weeks is capable of performing a threat display. The nestling period ranges from 95 to 115 days. But even after starting to fly, the juvenile eagle might remain close to the nest, and the parents continue to help it by bringing it food for another three months. Nestling and juvenile bateleurs sometimes fall prey to large eagles and owls. It takes the juvenile seven to eight years, passing through several moult stages, to acquire the typical adult colours. The juvenile at first also has a tail much longer than that of the adults; the tail feathers shorten at every moult stage until finally the tail has reached its minimal adult dimensions. After leaving the nest the juveniles may travel great distances to find suitable territories. They sometimes come together in large flocks, but these are temporary. At adulthood they'll have come to possess fixed territories.
An interesting feature of bateleurs is that they dribble fluid from their nostrils! This is seen especially with the youngsters, and usually happens while they're feeding, or sometimes when on a hot day they're panting. We're not quite sure what this is, but it might be a mechanism for excreting excess salts, beyond what the kidneys can handle. A nestling bateleur gets no water other than what is in the tissues of the prey items its parents bring it. Because of the heat, the youngster can lose a lot of water by evaporation; salts can therefore become concentrated in its blood. Glands in its nose are apparently able to concentrate the salts even more and then excrete this highly salty fluid, so removing the excess salt from the blood. This mechanism is well known with oceanic birds like albatrosses, petrels, penguins and others but apparently also occurs in many kinds of raptors.
Sadly, these unique eagles are also threatened. They used to occur all over South Africa (and also the rest of sub-Saharan Africa apart from the rainforest belt, and also Arabia) but today only remain in the far north. Their habits make them extremely vulnerable to poisoned carcases that farmers leave out to combat predators. They are often shot as well because they might catch chickens. They do receive protection in large game reserves like the Kruger National Park, but outside such areas their numbers continue to dwindle.
The 'Zimbabwe bird' – depicted in carved stone figures that were found in the Zimbabwe ruins and adopted as the country's emblem, also appearing on the national flag – might be a bateleur. There is also an organization in South Africa called 'Bateleurs' whose members are pilots providing their services in environmental causes – flying over areas to assess and examine the environment from above.
