Bateleur

The bateleur has been found to be a proper member of the subfamily Circaetinae, commonly called snake or serpent eagles, via a variety of genetic studies. Given the outward similarities of the bateleur to snake eagles, the relationship has long been inferred by authors. This relationship was well borne-out by a genetic study that found that this species and the short-toed snake eagle (Circaetus gallicus) form a monophyletic clade, based on nucleotide sequences in the cytochrome b gene. Even though, when contrasted with snake eagles, bateleurs appear to differ greatly in plumage patterns, the two genera show certain similarities in food, feeding behavior, and breeding biology. Chromosome banding studies have also found a relatively recent genetic relationship of the bateleurs with the Old World vultures. Etymology The common name of "Bateleur" is French for "street performer". Meanwhile, the scientific name is from name teras (Greek) for "marvelous"; ops (Greek) for "face"; e (Latin) for "without"; caudatus (Latin) "tail". ==Description==

The bateleur is of note for its unique morphology and plumage, with some anatomical similarities to both snake eagles and vultures. The species has a thick neck and a very large, rather conspicuously cowled head with a proportionately short bill, albeit one covered with a very large cere. The cowl is also present on snake eagles but in those it is less dramatically apparent. Its posture while perched is extremely upright, making them look like quite a tall raptor on the ground despite its rather short legs. Even while perched, the body tends to be dominated by their exceptionally large wings, which possess some 25 secondary feathers, perhaps more than any other raptor. The bare parts of adult bateleurs are exceptionally conspicuous, with the adult cere, bare facial skin and feet all being rather bright red, however in some they can also temporarily fade to pink, pale pink or yellowish at times, such as when they are perching in the shade or bathing. The bare parts flush the most red during times of excitement. The bill itself is black with a yellow centre and red base. The eyes are dark brown. 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. 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. 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. The total length of the bateleur is . Typical length of a full-grown bird is around . The wingspan of bateleurs can vary from . One sample of 10 unsexed bateleurs weighed an average of while a smaller sample of three weighed an average of . Additionally, a median body mass of was cited in one study. 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%. Identification The bateleur, particularly in its adult plumage, is often considered one of the most distinctive raptors in the world. When perched or flying adults or older immatures are quite unmistakable. 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. 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. 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. 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. Vocalizations Bateleurs are usually silent for much of the year. 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. Distraction display are sometimes accompanied by subdued barking chatter, ka-ka-ka-ka.... A not dissimilar call of kau-kau-kau-koaagh-koaggh has been described as given by perched birds. Other softer calls are uttered when perched near the nest. 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. ==Distribution==

The bateleur occupies a very large range through mainly sub-Saharan Africa. 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. 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. Similarly far north, a rare population is believed to persist out of Africa in extreme southwestern Saudi Arabia and western Yemen. 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. 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. The species is possibly extirpated from Eswatini in southern Africa. Vagrancy The bateleur is regarded as a vagrant in the countries of Tunisia, Cyprus and rarely Egypt, Israel and Iraq. In April 2012 a juvenile bateleur was seen in Algeciras in southern Spain. In 2015 and 2022, juveniles spotted as far north as Black Sea coast of Turkey in the cities of Istanbul and Sinop respectively. == Habitat ==

habitat in Botswana. The bateleur is a common to fairly common resident or nomadic Bateleurs are seldom to be found around extensive wetlands but may regularly be found near watering holes. In Ethiopia, it tends to be associated with well-wooded areas. The species can occur from sea level up to , but not normally a mountain-dwelling species and mainly occurs below . This is supported in Zimbabwe, where the bateleur is relatively common but appears to largely avoid the extensive amount of hilly and rugged areas present in that country. ==Behaviour==

This bateleur is unusually conspicuous due to its propensity for gliding flights over favorable habitats in much of Africa. 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". Although the species tends to fly fairly low, bateleurs can soar and circle quite high as well. In captivity, however, they become unusually tame. Bateleur eagles are among a group of raptors that secrete a clear, salty fluid from their nares whilst eating. According to Schmidt-Nielson's 1964 hypothesis, this is due to the general necessity for birds to use an extrarenal mechanism of salt secretion to aid water reabsorption. 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. Both immature and sometimes adult bateleurs are considered clearly nomadic. At times, the bateleur is even regarded as an "irruptive or local migrant". Some regular north-to-south movements may occur in West Africa and may occur transequatorially in East Africa to avoid heavy rains. 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. 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. At times, this is described as a "striking heraldic posture". ==Dietary biology==

carcass, in South Africa 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 . Additionally, they can also take birds on the wing. By the most complete picture of the bateleurs diet was a compilation study that compiled 1879 prey items from differing parts of the range. In the more hilly, rocky country of Zimbabwe, seemingly live prey was also preferred but a stronger prevalence of birds was detected among the 249 prey items. In this study, the main prey were scrub hares (22.8%), unidentified doves (10%), glossy starlings (6.72%), other small birds of around (6.69%), crested guineafowls (Guttera pucherani) (5.43%) and unidentified mammals (5.02%). In Kruger National Park, a much stronger preference for likely or verified carrion was detected in the bateleur's breeding season diet. Here, 731 food items in thornveld type habitat and 341 prey items in savanna type habitat were reviewed. It was estimated 31.6% of the diet was carrion was from medium-sized antelopes of around in weight, followed by small carrion sources of around to somewhat larger carrion from impala (Aepyceros melampus). Beyond carrion, the Kruger food study found that 16.4% of the total diet consisted of unidentified live mammals, 3.73% each by assorted dove species and lilac-breasted rollers (Coracias caudatus), 3% by glossy starlings and 1.6% by skinks. 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. Additionally, most African species of hare as well as, more secondarily, hedgehogs and elephant shrews and a variety of smallish carnivorous mammals. The latter may include live prey species including several species of mongoose, from dwarf to banded mongoose (Mungos mungo) and Selous's mongoose (Paracynictis selousi), both about the same body mass as a bateleur, and at least four species of genets as well as striped polecats (Ictonyx striatus). Over 30 mammal species have been identified as foods for bateleurs exclusive from carrion, including various larger food species, with carrion of ungulates ranging in size from that of Sharpe's grysbok (Raphicerus sharpei) to African buffalo (Syncerus caffer) and the carrion of carnivorans from the size of jackals to that of lions (Panthera leo). 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 , springhares estimated to weigh , Cape hyrax estimated to weigh , Kirk's dik diks estimated to weigh and greater cane rats estimated to weigh . with a coqui francolin kill. In all, a considerable diversity of birds and their eggs may be taken by bateleurs, perhaps around 80 species being known in their prey spectrum. They often focus on rather small, if normally live caught, birds compared to other eagles of a similar size. Much other similar avian prey, commonly those weighing around , including a surprising diversity of nightjars (perhaps since they are prone to end up as roadkill due to their predilection for resting on roads by night) and shorebirds like lapwings, other plovers, sandpipers and terns in addition to kingfishers (up to the size of the giant kingfisher (Megaceryle maxima)), rollers, hoopoes, small hornbills, parakeets and some passerines, usually those with a conspicuous presence on the savanna such as shrikes, weavers and starlings., Unlike many other eagles of similar or larger size, there are few instances of waterfowl or large waders (i.e. heron, storks, flamingoes, etc.) falling prey to bateleurs although at least one African spoonbill (Platalea alba) was recorded as bateleur prey. Mostly swarming social insects seem to attract bateleurs, including locusts. Other prey can include a rare amphibian, none of which are known to be identified to species or family. 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. 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. Bateleurs in particular are considered most likely to find a carcass first before other scavengers. 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. Therefore, the bateleur is considered a scavenger with high search efficiency but low competitive ability. 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. 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. It is uncommon-to-rare but not unprecedented that bateleurs may prey on other raptors. Bateleurs have been documented preying on black-winged kites (Elanus caeruleus), wintering lesser spotted eagles (Clanga pomarina), gabar goshawks (Micronisus gabar), barn owls (Tyto alba), spotted eagle-owls (Bubo africanus) and peregrine falcons (Falco peregrinus). Additionally, they were considered a likely potential predator upon nestlings of the white-backed vulture. Certainly the most impressive instance of intraguild predation documented as committed by bateleurs is when one was seen killing an adult Verreaux's eagle owl (Bubo lacteus), a formidable top predator among owls and possibly the largest avian prey ever reported for a bateleur. The predators of mature bateleurs themselves are not well-documented and in fact, Verreaux's eagle owls may the only species verified to repeatedly prey upon bateleurs, but this is probably due to rare predator identification at bateleur nests. Bateleurs are usually considered apex predators. By contrast, bateleur nestlings are vulnerable to predation compared to other raptors. Though adult bateleurs can simply leave the nest or crouch below the nest rim to reduce nest detectability to many predators, they can be very aggressive toward conspecifics as well as other raptors, and occasionally human intruders. However, due to their unique foraging mode which takes them far from the nest for long periods of the day, the physical defense is largely unable. Thus, chicks are presumed to be vulnerable to a huge range of predators although very few are properly identified. Based on other eagles in Africa, these are likely to include various sizes of mammalian carnivores, snakes, monitors and various birds of prey, including even perhaps much smaller species and vultures due to the long periods bateleur eaglets are left unprotected. An unprecedented instance of a leopard catching an adult Bateleur was filmed in Botswana. ==Breeding==

Bateleurs are long-lived species, slow-maturing, slow-breeding species, The bateleur breeding season tends to fall from September to May in West Africa, however juveniles have also been recorded in Mauritania in September. 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. In Somalia, the breeding season however fell from July to December while in Ethiopia there was no detectable peak whatsoever. Eggs and development of young In this species, only one egg is ever laid. A bateleur egg may measure from in height, with an average of in a sample of 24 and in a sample of 50, by in diameter, with an average of in 24 and 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. The incubation stage lasts for 52 to 59 days, averaging about 55 days, and may be the longest of any African raptor. Reports of incubation lasting for only 42–43 days are probably erroneous. 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 seems to be more likely than almost any other African eagle to desert their young. 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%. In East Africa, the bateleur tends not to breed every year and the replacement rate is about 0.5 per annum. In southern Africa, the bateleur typically breeds every year whether or not they are successful in raising their eaglet. At 4 nests in Zimbabwe, a replacement rate of 0.81 young per pair per annum, with local figures often being higher where they live more free from human disturbance. It was found that Zimbabwe failures were only known to be from infertile or lost eggs. In Kruger National Park, the predation of Verreaux's eagle-owls may considerably lower nesting success. Furthermore in Kruger, it was found that 33% of the population of bateleurs were young birds while the remaining 67% were adults, meaning that younger birds are presumably underpopulated. Elsewhere, even lower numbers, around 25-30%, of the population is young bateleurs. The population, or at least in southern Africa, seems to be roughly even in terms of sex ratio, with an even number of males and females. In the Kalahari Gemsbok National Park, 13 pairs of bateleurs were recorded to produce only 0.33 young per pair. There was evidence of a 13% decline in active nesting territories of bateleurs in the Kalahari Gemsbok area during the seven year study, and at least a 40% decline over the previous 10 years. Vacated nesting territories were not reoccupied by the species. There was found to be seemingly no safe buffer zone around the park, due perhaps to persecution in the adjacent farmlands, when potential mortality of foraging bateleur from the protected park enter these areas, as well as nesting site disturbance, could have been part of the reason for this decline. Poisoned and suspected poisoned bateleurs have been found in the Park during the study period. The few that survive their early years may expect a mean estimated lifespan of around 12–14 years and in some cases may manage to live as long as 27 years. The annual adult survival rate is estimated at 95%, while the annual juvenile survival rate is estimated at 75%. ==Conservation==

Bateleurs are a wide ranging species but have shown rather strong declines. In all the bateleur has declined by an estimated 75% in Southern Africa. The species is considered threatened in Zimbabwe, Namibia, Eswatini and South Africa and still considered not uncommon but probably declining in Malawi, Zambia, Mozambique and Botswana. Declines are not endemic to Southern Africa for bateleurs, with declines strongly detected as well in Ivory Coast and Sudan. Where bateleurs were once common in road surveys in Central-West Africa, none were detected in newer road surveys from the 2000s in the same areas. Claims of an increase in potential numbers of bateleur in Uganda are not verified. The declines of the species are almost entirely due to anthropogenic causes. Poisoning of carcasses is a major issue for scavenging animals, especially birds like vultures in Africa. 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. 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. Additionally, shrinking habitat has been found to be a prevalent threat to bateleurs due largely to expanding human settlements and intensifying livestock agriculture. ==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. A South African myth was that when bateleurs "cries in flight, the rain will fall". 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 the bateleur variously known as kgwadira and petleke, and may often in mythology fulfill the role of intelligent servant to their masters, which were considered vultures. In East and Central Africa, the bateleur has been referred to variously as gawarakko and nkona and in the Lake Tanganyika region was considered an essential possession of sultans whether the birds were dead or alive. ==Media==

File:A Bateleur Eagle mid blink.jpg|A bateleur blinking showing off the nictitating membrane File:Bukázó sas 1.jpg|Female sunwarming in a zoo File:Bateleur Eagle.jpg|Immature File:Bateleur.jpg|Female in Texas File:Terathopius ecaudatus.ogv|A female perched on a gloved hand in Disney's Animal Kingdom File:Bateleur Eagle skeleton.jpg|Skeleton of a bateleur eagle (Museum of Osteology) File:Bateleur, KNP, South Africa imported from iNaturalist photo 13753270.jpg|In South Africa ==References==