Bateleur
Bateleur | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Accipitriformes |
Family: | Accipitridae |
Subfamily: | Circaetinae |
Genus: | Terathopius Lesson , 1830
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Species: | T. ecaudatus
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Binomial name | |
Terathopius ecaudatus (Daudin, 1800)
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approximate breeding range |
The bateleur (
This species is native to broad areas of
Taxonomy and etymology
The bateleur has been found to be a proper member of the subfamily
The common name of "Bateleur" is French for "street performer".[18] Meanwhile, the scientific name is from name teras (Greek) for "marvelous"; ops (Greek) for "face"; e (Latin) for "without"; caudatus (Latin) "tail".[7] The bird was given its common name by François Levaillant, a French naturalist and explorer.[7] The original scientific name was Falco ecaudatus, given by François Marie Daudin, as the concept of disparate genera between birds of prey was devised later on (nor were falcons then known to be unrelated to many other variety of diurnal birds of prey).[19]
Description
The bateleur is of note for its unique morphology and plumage, with some anatomical similarities to both snake eagles and
The juvenile is very distinct from the adults of the species. Juveniles of the bateleur have a longer tail than mature birds. They furthermore have essentially all brown coloring, with dull rufous to creamy edging apparent on some areas. The head of the juvenile bateleur is paler and tawnier than elsewhere on its body while the eyes are brown, the cere a rather unique greenish-blue and the feet whitish in colour.[5][22][23] At as late as 2–3 years of age, the immature bateleur is still much the same in appearance as the juvenile but by the fourth year becomes more sooty-brown, with sexual dimorphism already evidenced by the more extensive dark wing markings of males. In the 5th year, the plumage may show the first signs of chestnut and the grey colour about back and shoulders tend to manifest. Also from 3–5 years old, the cere and feet turn yellow then to dull-pink. By the sixth and seventh years of life, the plumage of subadult bateleurs blackens and the chestnut portions of the plumage increase. The shoulders become fully grey by the 8th year, the likely age of maturity.[5][24] As for the bare parts in juvenile bateleurs, the cere and facial skin are a distinct pale grey-blue to green-blue. The juvenile's feet are greenish-white to greyish-white, at 4-5 the cere, facial skin and feet turn yellow, then pink before finally reddening. The eyes are similar in hue to those of adult bateleurs but are a slightly lighter, being more honey-brown, while the bill of juveniles are mainly pale grey-blue in colour.[5][7]
In flight, the bateleur appears as a rather large raptor with disproportionately elongated, rather narrow and slightly bow-shaped wings, which appear pinched in at the bases, broad across the secondaries and regularly narrow, pointed and upturned at the tips. Upon sighting, the wings often catch the eye before the large head, which is proportionately slightly bigger even than their cousins, the snake eagles.[5][25] The tail is so short in adult bateleurs that the feet extend below the tail tip, almost giving the impression that the raptor nearly has no tail.[5][20] This is as opposed to juveniles, where the feet come up about 5 cm (2.0 in) short of the tail tip, with the feet coming to exceed the tail, which is shrinking via moults, in length around the 5th year of maturation.[5][7] The adult bateleur's wingspan is an extraordinary 2.9 times greater than its total length.[5] The adult male bateleur is mostly black above with a chestnut back and tail and grey forewings, below he is black on the body, contrasting with a chestnut tail, as well as with the white wing linings and black flight feathers except for the greyish based primaries. The adult female bateleur is similar in plumage to the male overall but differs in her black-tipped grey secondaries above and more extensively white underwings with the black on the female confined to the wingtips and trailing edges.[5][20] The juvenile bateleur on the wing appears broader winged and especially longer tailed with a largely uniform brown coloration, including the greater coverts, with paler feather mainly about the head as well as on the flight feathers.[5]
Size
The bateleur is a mid-sized eagle and large raptor. It is likely the second heaviest of the
The bateleur evidences some sexual dimorphism in favour of the female as is expected in raptorial birds but this size difference is fairly minimal relative to many other accipitrids, averaging up to about 6%.[5] Among standard measurements, males have a wing chord length of 476 to 553 mm (18.7 to 21.8 in) while that of the female is 530 to 559 mm (20.9 to 22.0 in). In tail length, adult males measure 98 to 124 mm (3.9 to 4.9 in) and can be even shorter in adult females at 105 to 113 mm (4.1 to 4.4 in), in some cases the adult's tail may reportedly measure as short as 72 mm (2.8 in). This contrasts with the tail of juvenile bateleurs which measures 142 to 172 mm (5.6 to 6.8 in). The tarsus can measure from 67 to 75 mm (2.6 to 3.0 in) in males and 72 to 75 mm (2.8 to 3.0 in) in females. Unsexed adult bateleurs in Tsavo East National Park were found to average 513 mm (20.2 in) in wing chord length, 34.5 mm (1.36 in) with a range of 28.6 to 38 mm (1.13 to 1.50 in) in culmen length and a relatively small hind claw length of 30.6 mm (1.20 in). While the hind or hallux claw is usually the most enlarged in most species of accipitrid, on the other hand in the Tsavo East bateleurs, unusually the middle claw on the front of the foot was slightly larger at 32 mm (1.3 in). Notably the proportions of bateleurs are similar to snake eagles with robust feet with rough, thick skin and short talons, the bateleur in particular having very thick, large toes structurally almost like those of a big owl and very sharp talons reminiscent in sharpness of highly predaceous larger African raptors. Further like snake eagles, bateleurs have a rather large headed but with a smallish beak coupled with a large gape. These adaptations generally equip the subfamily to better handle and ingest snakes relative to other accipitrids.[5][33][34][35]
Identification
The bateleur, particularly in its adult plumage, is often considered one of the most distinctive raptors in the world.[36] When perched or flying adults or older immatures are quite unmistakable.[5] The bateleur can be readily be distinguished even by inexperienced observers from the very differently-shaped and usually rather smaller-bodied and winged augur buzzards (Buteo augur) and jackal buzzards (Buteo rufofuscus). These do not overlap with bateleurs in nearly all respects of morphology, proportions nor flight actions. Nonetheless, both of these buzzards are sometimes mistaken for bateleurs due to their own combinations of black, white and chestnut, which are completely differently composed than those of the bateleur.[5][20][25] Despite how distinctive the buzzards are from the bateleur, some reports of bateleurs from areas where they are currently gone are almost certain to have been misidentified jackal buzzards.[7] Juveniles and immatures of up to 2–3 years old are hardly less distinctive in shape but could be confused, largely due to similar proportions of their large head, brown plumage and whitish legs with certain snake eagles. The brown snake eagle is perhaps the most similar to the juvenile bateleur but it has yellow eyes, longer legs, much broader, shorter and differently shaped wings with the tips of wings reaching its banded tail.[5][7] Even the black-chested and the rather slight Beaudouin's snake eagle (Circaetus beaudouinii) are sometimes considered potentially confusable with juvenile bateleurs, but both of these respective species are rather uniform and darker brown ventrally and about the head and much paler dorsally, with a highly different contrasting whitish cream colour below.[5]
Vocalizations
Bateleurs are usually silent for much of the year.[5] The main call, uttered whether perched or in aerial display, or when pirating from other raptors, is a far-carrying, loud raucous schaaaa-aw. They may too vocalize in a similar manner during courtship. Alternatively, bateleur calls may consist of resonant barking calls, kow-aw. The barking call can be accompanied by half-spread wings and jerking of the body up and down or may too be uttered in flight, the latter in a similar manner to that of a fish eagle.[5][10] Distraction display are sometimes accompanied by subdued barking chatter, ka-ka-ka-ka....[5][34] A not dissimilar call of kau-kau-kau-koaagh-koaggh has been described as given by perched birds.[10] Other softer calls are uttered when perched near the nest.[5] The young of the bateleur tend to engage harsh squealing call is kyup-kyup keeaw keeaw, usually as a hunger call at approach of parent with food. Also the species' young may make a melodious twip call.[10][34]
Distribution and habitat
The bateleur occupies a very large range through mainly sub-Saharan Africa.[5][37] The species resides in West Africa from southern Mauritania to Senegal, The Gambia, Guinea-Bissau, Guinea, the northern portions of Sierra Leone, Ivory Coast and much of Ghana through western Burkina Faso, much of Togo and Benin and northern and central Nigeria.[1][38][39][40] It is possibly extinct in Mauritania, range restricted in Guinea (mainly to Kiang West) and Liberia but is still locally common where good habitat remains elsewhere in this region.[41][42] Similarly far north, a rare population is believed to persist out of Africa in extreme southwestern Saudi Arabia and western Yemen.[43][44] In central and east Africa, the bateleur may be found in northern Cameroon, southern Niger, southern Chad, southern Sudan, South Sudan, northern Central African Republic, Eritrea, Ethiopia, Djibouti, western Somalia, northern, eastern and southern Democratic Republic of the Congo and a majority of Uganda, Kenya and Tanzania.[45][46][47][48][49] In Southern Africa, the bateleur is found quite widely, being found almost throughout, where habitat is favorable, Angola, Zambia, Zimbabwe, Malawi and Mozambique. Additionally, they may range Botswana in all but southernmost portion also being found still in northern and eastern Namibia and northwestern South Africa, where its range has contracted considerably from as far south once as the Cape Province to almost entirely to being found exclusively within protected areas north of the Orange River excepting a portion of Kruger National Park.[13][50][51][52][53][54][55] The species is possibly extirpated from Eswatini in southern Africa.[56] The bateleur is regarded as a vagrant in the countries of Tunisia, Cyprus and rarely Egypt, Israel and Iraq.[5][57][58] In April 2012 a juvenile bateleur was seen in Algeciras in southern Spain.[59] In 2015 and 2022, juveniles spotted as far north as Black Sea coast of Turkey in the cities of Istanbul and Sinop respectively. [60]
Habitat
The bateleur is a common to fairly common resident or nomadic
Behaviour
This bateleur is unusually conspicuous due to its propensity for gliding flights over favorable habitats in much of Africa.[7] The bird spends a considerable amount of time on the wing, particularly in low-altitude flights.[64] Due to the conspicuous behaviour and colorful plumage, the bateleur is frequently described in superlatives such as "one of the most beautiful and spectacular things that flies".[10] This species tends to take off with unusually fast, shallow beats for a bird of this relative large size.[5] After take-off, the bateleur sails at a mean speed of about 50 to 60 km/h (31 to 37 mph). They often rock from side-to-side with the wings held in a strong dihedral with very limiting flapping, vaguely recalling the flight of the American turkey vulture (Cathares aura) although the flight is generally more forceful, fast and acrobatic than that species and at times can be evocative of a huge falcon.[65][66] Although the species tends to fly fairly low, bateleurs can soar and circle quite high as well.[5][10][20] Engaged in its aforementioned dihedral flight it is often cants continuously from side-to-side, likely the origin of which it was given its common name (loosely "tumbler", "balancer" or "tightrope walker") of French derivation.[10] Various flying embellishments may be undertaken nearly aseasonally.[5][34] Although not typically given to forward somersault nor to loop-the-loop, bateleurs may with some regularity perform a rapid 360 degrees sideways roll.[10] They are often given to flying with more embellishments when in the presence of another bateleur, even with juveniles provoking one another entirely uncoupled seemingly from breeding courtship or territorial displays.[5] Typical home ranges of around 40 km2 (15 sq mi) were reported per pair in Kruger National Park and these were considered unusually small by overall species standards.[5] Intruders to whom this behaviour is displayed always submit and submission is shown by retreating to a safe upper boundary (elevation). Males and females both display this behaviour in all stages of the breeding cycle. This behaviour is mainly shown to members of the same sex and particularly to non-adults, as it is thought that they may have a greater ability to take over another bird's territory (having greater competitive ability for limited food resources).[8]
The bateleur is generally a solitary bird. However, juveniles may accompany one or both parents for about three months and loose congregations of as many as 40-50 or more have been record of mainly immatures. These tend to be
Nomadism and dispersals
Generally, as in most raptors found as breeding residents in Africa, the bateleur is considered sedentary and territorial but it is a species that requires very large home ranges.
Thermoregulation
Bateleurs seem to devote an exceptional amount of time to thermoregulation frequently spending much of its day variously sunning, to warm up, and bathing, to cool off.[34] These eagles are frequently seen to enter water-bodies for a bath and then open their wings to often sunbathe. Standing upright and holding their wings straight out to the sides and tipped vertically, a classic 'phoenix' pose as they turn to follow the sun.[74] Bateleurs will stand on the ground with their wings spread, exposing the feathers to direct sunlight, warming the oils in the feathers. The bird will then spread the oils with its beak to improve its aerodynamics. In some countries, local nicknames of the species may include as the "Conifer eagle" or "Pine eagle" due to its feathers resembling a conifer cone when fluffed up and engaging in thermoregulatory behaviour.[75][76][77] At times, this is described as a "striking heraldic posture".[7] Bateleurs may also be seen "praying" allowing ants to crawl over the wings and feathers, collecting bits of food, dead feather and skin material. When covered in ants, the bateleur then ruffles its feathers, startling the ants, which react by secreting formic acid as self-defence. This in turn kills the ticks and fleas, possibly ridding the host of its parasites.[78]
Dietary biology
The bateleur is a dietary generalist. This species generally forages from the flight, flying mostly low and straight whilst scanning the ground, periodically banking and retracing sections of the track when possible foods are spotted. Their hunting range can be truly enormous ranging in some cases up to 55 to 200 km2 (21 to 77 sq mi).[5][23] Bateleurs may spend up to 8–9 hours or up to 80% of daylight on the wing, perhaps largely for hunting and foraging purposes, and have reported having even covered as much as 300 to 500 km (190 to 310 mi) in a single day.[5] When potential prey or food is spotted, they then descend in tight spirals to check it out.[5] The bateleur is a very effective discoverer of carrion at all times and often is the first to come to large carcasses or roadkills.[5][13] Juveniles appear to attend large carrion much more than adults and dietary studies appear to support that carrion is rather more significant to the foods of juvenile and immature bateleurs compared to adults.[5][7][33] Despite an aptitude for scavenging, descriptions of this eagle as "not a very rapacious species" are erroneous as it has been found to a highly powerful predator for its size and one that is often rather active at pursuing living prey, with seemingly most food consumed during the breeding season being prey that the bateleur has itself killed.[10][7][33] Bateleurs kill most prey on the ground with a steep stoop on partially closed wings. On the evidence, they may alter their stoop onto prey with a slow drop with raised wings, rather in a gentle descent like a parachute, largely when taking slower moving prey such as some reptiles.[5][7][79][80] Additionally, they can also take birds on the wing.[79] As occasional kleptoparasites, they sometimes aerially pirate foods from other raptors. Alternately, they may try to intercept other raptors' kills while the raptor is feeding on them, whether it be on the ground, in a tree or on a rock, or even immediately after the kill is made.[5][7] These piratical attacks are sometimes carried out against large carrion eaters like vultures and even against larger eagles, and in them, they may drive their target to the ground, with interlocking talons or trading shallow blows with their feet.[7][79] Bateleurs also hunt insects by walking on the ground, particularly after grassfires, and will patrol for small carcasses alongside roads.[5]
Bateleurs forage almost entirely based on opportunity and have no particular specialization on any particular prey type.[7] As a result, a wide prey spectrum has been reported, with around 160 prey species known, they thus rival martial eagles (Polemaetus bellicosus) and perhaps just slightly behind tawny eagles (Aquila rapax) as the most diversified feeder known among African eagles.[7][6][33][79] Among their prey, mammals, birds and reptiles, roughly in that order, seem to be considerably preferred over other prey taxa.[7][79] Based on morphology, their long middle toes have been cited as an indication that they originally diversified to become a bird-eater but a rather small degree of sexual dimorphism between males and females indicates a preference for mammal eating.[5][81][82] By the most complete picture of the bateleurs diet was a compilation study that compiled 1879 prey items from differing parts of the range.[79] In it was found that bateleurs derived 54.6% of the diet from mammals, with perhaps two-thirds to about half of the diet being mammalian carrion, along with 23.7% of the diet being from birds, 17.8% from reptiles, 1.9% from fish, 1.8% from invertebrates and an extremely small amount (about 0.2%) of amphibian food.[79] Predominantly, within the compilation study, preys were unidentified to species, with 58.4% of the carrion sources, 26.9% of live mammals, genera, or families, and 22.2% of birds unidentified to species.[79]
Differing study areas show differing prey results for bateleurs.
In general, a picture emerges that the primary food sources of bateleurs are live-taken medium-sized mammals, carrion of generally larger mammal species, rather smallish bird prey, and a small diversity of reptiles.
Outside of galagos, among primate foods most monkeys observed in the diet such as baboons and vervet monkeys (Chlorocebus pygerythrus) are thought to be largely scavenged as carrion.[79][80] However, studies of king colobus (Colobus polykomos) and Angola colobus (Colobus angolensis) in Central and southeastern Africa (both where few details are known of bateleurs' diets), it was mentioned bateleurs may be a potential predator of troops based on the anti-predator activity and vocalizations of these species provoked by bateleurs.[90][91] The bateleur, using its large, powerful feet, does not shy away from very large prey and has been known to regularly kill mammals heavier than itself including scrub hare estimated to weigh 2,600 g (5.7 lb), springhares estimated to weigh 3,000 g (6.6 lb), Cape hyrax estimated to weigh 3,800 g (8.4 lb), Kirk's dik diks estimated to weigh 4,000 g (8.8 lb) and greater cane rats estimated to weigh 4,500 g (9.9 lb).[33][79] Even more impressive mammalian kills have been suspected, with instances where reportedly adults black-backed jackals (Canis mesomelas), honey badgers (Mellivora capensis), and aardwolf (Protelas cristatus), any of which may weigh around twice the aforementioned large mammal prey for bateleurs, may have been unexpectedly killed by bateleurs.[13][33][80] Furthermore, an instance of attempted predation in Tanzania on an adult honey badger was witnessed, ending with both the bateleur and badger dying from the ensuing fight.[92]
In all, a considerable diversity of birds may be taken by bateleurs, perhaps around 80 species being known in their prey spectrum.
The bateleur was once reported to be a very common predator of reptiles like their cousins the snake eagles.
Interspecific predatory relationships
The bateleur seems to adapt to living in the highly competitive continent of Africa by foraging with a lack of specialization, with a seeming lack of discrimination regarding the prey item/food source nor its origin although its highly aerial and free-ranging foraging mode is quite unique.[10][7] The bateleur, nonetheless, must face considerable and intense competition from other birds of prey especially.[7] The range of other raptors, especially other eagles and vultures, may appear to be daunting.[7][6] One of the most similar eagles to regularly encounter the bateleur is the tawny eagle. These two species overlap in many significant ways, being similar in body mass and predatory prowess as well as in nesting habitat, tendency to attack a wide size range of prey (including large prey) and general disposition. Furthermore, both of these eagles show ability to freely change feeding methods between live predation, scavenging on carrion and piracy.[7][9] In Tsavo East National Park, bateleurs were studied along with tawny eagles, significantly larger martial eagles and slightly smaller African hawk-eagles (Aquila spilogaster).[33] Here all four largish eagles relied primarily upon Kirk's dik dik for food but were mostly slightly staggered in breeding season, with the bateleur nesting on average earlier than the other eagles.[33] The diet was by far most similar with that tawny eagle in Tsavo East, overlapping 66% in prey species and 72% in prey weight. Meanwhile, the diet overlapped 32% in species and 50% in weight with martial eagles and 37% in species and 57% in weight with African hawk-eagles. The one discrepancy, which is noted in other studies as well, is that the bateleur tends to focus on smaller birds than tawny eagles when selecting avian prey.[7][33][99] Bateleurs also bear an advantage over tawny eagles in their ability forage in open habitats, with the absence of perches, due to their aerial foraging methods.[33] However, data indicates that the tawny eagles is dominant over bateleurs typically at disputed kills or carrion.[7][100] One study accrued 26 instances of tawny eagles displacing bateleurs against only 5 where bateleurs displaced tawny eagles, giving illustration to the tawny eagles dominance. Frequently, the bateleur waits until the tawny eagle is done eating before it does so itself if both are at a carcass site.[101]
Bateleurs may encounter a huge range of other scavengers when coming to carrion. Most clearly vultures are often present at carrion. However, due to their smaller size, the tawny eagle and especially the bateleur can begin foraging for carrion earlier in the morning, while the vultures must wait for updrafts to undertake flight.[102][103] Bateleurs in particular are considered most likely to find a carcass first before other scavengers.[103][104] This was verified in a study in Maasai Mara where it was additionally found that scavengers kept to body size in terms of hierarchy. The descending order of scavenger dominance was stated to rank starting with the spotted hyenas (Crocuta croctua) at the top and black-backed jackals and feral dogs (Canis lupus familiaris), then the lappet-faced vulture (Torgos tracheliotos), the Rüppell's vulture (Gyps rueppellii), followed by all other vultures with the tawny eagle and the bateleur in the second most and the most subordinate scavenger positions.[105] Therefore, the bateleur is considered a scavenger with high search efficiency but low competitive ability.[103][104][105][106] However, the bateleur does benefit from the larger scavengers, being less able to access a large carcass, at best feeding on the eyes of said carcass unless it is already otherwise torn asunder such as large carnivore prey or roadkills.[13][104] With the epidemic-level reduction of vultures in Africa, it was found in Maasai Mara that both bateleurs and tawny eagles have been found to actually increase in sighting frequency in sync with the vanishing numbers of remaining vultures, with the number of bateleur sightings increasing by 52%.[107] To the contrary of the expected hierarchy, cases are known where bateleurs have attacked and dominated much larger scavenging birds including white-backed vultures (Gyps africanus) and bearded vulures (Gypaetus barbatus), with these having been successfully displaced or lost carrion to a bateleur.[10][6] Even more impressively, cases where bateleurs interacting with much larger, more powerful martial eagles have involved instances where the bateleurs have attacked, pirated and even brought to ground in clashes that appear to end in a drawl. However, the martial eagle occupies a notably higher trophic level than the bateleurs and is not considered subservient to bateleurs due its even greater predatory prowess.[7][34][79] Similarly, instances of considerable competition have been reported between bateleurs and African fish eagles (Haliaeetus vocifer), which are similarly prone to opportunistic piracy and aggressive interspecific relations. However, the two species are partitioned by habitat and primary prey.[108]
It is uncommon-to-rare but not unprecedented that bateleurs may prey on other raptors.
Breeding
Bateleurs are long-lived species, slow-maturing, slow-breeding species,[61] Bateleurs court each other or re-establish existing pair bonds what is considered, a "spectacular" courtship display.[10][7] During the courtship display, an exaggerated flight is undertaken, in which the male dives down at the female who rolls to present him her claws. Additionally, he sometimes flies with legs dangling loosely, during which the wings may be flapped to create a conspicuous whup-whup-whup noise like a loose sail in the breeze. Very infrequently, a male bateleur may make a 360 degree lateral roll, accompanied by loud whup-whup noises, at times display may involve 2 males with a single female, but during breeding only one male is usually actively courtship. A further chasing flight reported is not necessarily nuptial and may be performed by birds of the same size and by an adult or an immature and in some cases is linked to the sociality of the species.[5][10][7][34][79] The bateleur is usually rather monogamous and likely, with the survivorship of each mate, mates for life.[7] However, rare instances of possible polygyny have been reported.[117] The bateleur breeding season tends to fall from September to May in West Africa, however juveniles have also been recorded in Mauritania in September.[5][41][118] Reportedly, the nesting season can be virtually any month in East Africa but chiefly is some time around December–August, which also is the corresponding peak breeding time in Southern Africa, with nesting as late as August to October in the southern stretches of the continent considered unusual.[5][7][51][52][54][119][120] In Somalia, the breeding season however fell from July to December while in Ethiopia there was no detectable peak whatsoever.[46][47]
Nests
Nests are located in fairly large trees, sometimes near a watercourse, either in
Eggs and development of young
In this species, only one egg is ever laid.[5][7][51][52] Their eggs are quite large for the size of the bird, being broadly oval and usually an unspotted chalky white but sometimes with a few red stains or indistinct reddish markings, which may be cosmetic from feeding and defecating of the parents. The bateleur's egg is quite similar in size and coloration to most snake eagles, which also generally lay a single egg.[5][10][7][122] A bateleur egg may measure from 74.2 to 87 mm (2.92 to 3.43 in) in height, with an average of 77.4 mm (3.05 in) in a sample of 24 and 79.1 mm (3.11 in) in a sample of 50, by 57 to 68.1 mm (2.24 to 2.68 in) in diameter, with an average of 62.3 mm (2.45 in) in 24 and 62.7 mm (2.47 in) in 50. The eggs are comparable in size to those of martial and crowned eagles (Stephanoaetus cornatus), eagles of easily up to twice the body size of a bateleur.[10][7][34][120] The female bateleur normally incubates alone, though rarely males are seen to do so as well.[7][79] The female is fed by the male but takes spells off in which she probably feeds on her own kills and the male may take over incubation, although reports of instances where he may do the majority of incubation are probably inaccurate.[10][7] While the elastic breeding season suggests an indifference to climatic concerns relative to the wet season and dry season, the bateleur is usually considered an eagle that lays earlier in the year than overlapping eagles.[33][123][124] The incubation stage lasts for 52 to 59 days, averaging about 55 days, and may the longest of any African raptor. Reports of incubation lasting for only 42–43 days are probably erroneous.[5][10][7][120]
The hatchling is highly
Parental behaviour
When the nest is approached, at times bateleurs will react forcibly, engaging in aggressive barks, sometimes diving down from flight at the intruder with loud flapping wings. When disturbed in this way, however bateleurs very often depart and they will often not return to the nest for up to several hours. Generally, it seem to be more likely than almost any other African eagle to desert their young.[10][7][79] During the incubation and nestling period, the male is more demonstrative than the female at the nest, sometimes doing the distraction display and regular dive-bomb attacks if the nest tree is climbed, the female more commonly flies away in the distance. Once a lone male baboon climbed a nest tree, the female bateleur sat and incubated while the male dive bombed it. When this failed to drive it off, the male settled on a branch between the baboon and the nest and threatened the monkey with raised wings, the baboon was never dislodged but did not harass the eagles at the nest.[10][7] Bateleur parents are highly sensitive to breeding from human disturbance, oddly they may permit and adapt to regular inspections of the nest but resent an attempts to hide or conceal photographic equipment nearby and regular desert the nest even with a small nestling, thus nest photography should be avoided.[10][7][79] The ease with which bateleurs are flushed away from their nest appears to lead to uncommonly high nest predation rates, while many other eagle, including from other parts of the world, either sit tightly on their nest until the danger level becomes too high or attack ferociously at the potential threat.[7][101][126] The nestling is careful tended to by female, as she is at the nest 82% of the time up to the time the eaglet is 10 days in one Kenya study, her attendance thence drops to 47% from 10–20 days, then after 30 days, dropped to about 5% and from 60 days about 1%.[10][7] When the young is at later stages of maturity, the female tends to only engage in very brief prey deliveries.[10][7] Both sexes bring prey and feed the young though the male takes a bigger share of this than in many eagles.[10][7] After 30 days, the eaglet is often left by itself on the nest throughout the night.[10] The eaglet is fed nearly every day early on but only every 2–3 days later on, especially after leaving the nest.[10]
Breeding success and failures
It is estimated that the bateleur produces a mean of 0.47 chicks per nest per year.
Conservation
Bateleurs are a wide ranging species but have shown rather strong declines.
Decline of the species and the reduction in range is suspected to have been moderately rapid over the past three generations. Generally, throughout the range, the bateleur is considered much more common in protected areas.[13][129] However even in several protected areas, numbers of bateleurs seem to decreasing.[135][136] The declines of the species are almost entirely due to anthropogenic causes.[5][13] These include but are not limited to habitat destruction, the poisoning of carcasses, persecution through shooting and possibly pesticide use.[5][137] Poisoning of carcasses is a major issue for scavenging animals, especially birds like vultures, in Africa.[138][139] Zambian bateleurs may suffer from deliberate poisonings as well as those in Eswatini, Botswana, Zimbabwe and Mozambique. The bateleur's wide foraging areas and their ability to locate very small pieces of carrion, makes them highly susceptible to poison-laced carcasses even from a small proportion of farmers who use poisons. Bateleurs and other eagles are not usually the direct target of these poisoning operations, which in some cases may be directed to unfavored mammals like jackals or in other cases directed towards vultures by poachers to hide their illegal wildlife killings.[13][51][54][63][139] The decline of South African bateleurs is primarily linked with poisonings, primarily from large-scale farming operations.[79][140][141] It is possible that bateleurs may suffer from the effects of DDT though it is found in a small sample of 3 eggs from South Africa that they evidenced low subcritical levels of DDT metabolites, probably not enough to effect overall populations.[5][129] However, it is projected that pesticide use may be harming populations in Zambia as well as in Botswana.[53][51] Ongoing persecution is both serious and unsustainable, beyond poisoning, such killings are known to extent to ongoing shooting and trapping.[1][13][129] Some trapping occurs of the species for its feathers which are used in medicine by traditional healers for predicting future events[61] Less well known but probably occurring declines may be due to flying into manmade objects including wire collisions, reservoir drownings and road-killings.[142] Additionally, shrinking habitat has been found to be a prevalent threat to bateleurs due largely to expanding human settlements and intensifying livestock agriculture.[13][63] A further effect from humans is regular disturbance at bateleur nests, although not typically as deliberate as many other threats, this is causing the breeding success rates to plummet farther.[7][13][129] No large scale actions are underway but they are possibly protected in Yemen as an endangered species.[23] It is proposed to implement education and awareness campaigns across its range to reduce the use of poisoned baits. Regular population monitoring is being carried out.[143]
Heraldic and mythological status
The bateleur plays a prominent role in African heraldic and mythological cultures probably due to its spectacular colours and conspicuous and bold behaviour.[10][34] As a result it is likely that the bateleur is the basis for the "Zimbabwe Bird" which has been prominent since ancient times in Zimbabwean culture and continuously used in heraldic forms including most prominently being featured on the Zimbabwe flag.[144][145] A South African myth was that when bateleurs "cries in flight, the rain will fall".[146] The admiration and mythologizing of bateleurs is also known in other areas beyond Zimbabwe, including among those in Southern Africa who speak Tswana language as well as elsewhere dating back to the Iron Age with various with the bateleur variously known as kgwadira and petleke, and may often in mythology may fulfill the role intelligent servant to their masters, which were considered vultures.[147][148] In East and Central Africa, the bateleur has been referred to variously as gawarakko and nkona and in the Lake Tanganyika was considered an essential possession of sultans whether the birds were dead or alive.[149][150]
Media
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A Bateleur blinking showing off the nictitating membrane
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Adult
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A female sunwarming in a zoo
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Immature
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A female perched on a gloved hand in Disney's Animal Kingdom
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Female in Texas
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Two juveniles in Botswana
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Skeleton of a bateleur eagle (Museum of Osteology)
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