Keilschwanzadler

Bestimmung

Wedge-tailed eagles are very large and quite lanky birds. They are characteristically black but can appear tar to charcoal brown, depending on lighting and individual variation. They have a massive bill but possess a relatively small and rather flat head, with a long, almost vulturine neck. Furthermore, they are distinctive for their prominent carpals and baggy feathered trousers. The species tends to perch conspicuously on dead trees, telegraph poles, rocks or, at times, the open ground. Between the bill size, elongated shape and prominent shoulders, the species is highly distinctive. While perched, their long wings extend down to a long and markedly wedge-tipped tail.<p>They have a large proportion of bare facial skin, which is thought to be an adaptation to the warm climate rather than carrion eating, because the non-carrion-eating Verreaux's eagle has similar facial feathering and the golden eagle eats carrion too. Against the blackish plumage, the tawny-rufous hackles on the neck, forming a lanceolated shape, as well as the pale brown to rufous crissum, and narrow mottled grey-brown band across the greater wing coverts, all stand out well. The sexes are indistinguishable by plumage.<p>The juvenile is mainly darkish brown, with extensive rufous feather edging, and a paler, fairly streaky head. Furthermore, the juvenile has a lighter-brown crissum, and a light reddish-brown to golden nape, with similar colouring extending sometimes to the back and wing band. The wing band is considerably more prominent than those of adults, extending to the median and sometimes the lesser coverts. Rarely, a juvenile may be all dull black, lacking rufous edges or a wing band. Young eagles are much the same by the second through to the fourth years though they may be almost invariably visibly in moult and with a narrowing wing band. They become darker around the fifth year, with a red-brown nape and a still narrowing wing band. Full mature plumage is not attained until the seventh or eighth year, although sexual maturity can be considered as early as five.<p>Adults have dark brown eyes, while juveniles usually have similar but slightly darker eyes. Wedge-tailed eagles are typically creamy white on the cere and feet, although those can be dull yellow, more so in juveniles than adults. The wedge-tailed eagle has a unique moult process in that they moult almost continuously and very slowly, and it might take three or more years for an eagle of the species to complete a moult. Moults are arrested only at times of famine, and happen gradually, so that they do not impede the bird's flight or hunting capacities.<p>In flight, wedge-tailed eagles appear as a very large, dark raptor, with a protruding head, long and relatively narrow-looking wings, more or less parallel edged when soaring and, most distinctly, a long diamond-shaped tail. The shape is dissimilar to any other raptor in the world. Juveniles tend to be broader winged by comparison. The wingspan is around 2.2 times greater than the bird's total length. They tend to fly with rather loose but deep and powerful beats. Wedge-tailed eagles spend much time sailing along, looking quite stable and controlled even in strong winds. The species glides and soars on upswept wings with long splayed primaries. The ample tail may be upcurved, or "dished", at the edges. The eagle often spreads its deep wing emarginations to reduce drag in high winds. Contrary to their superlative and controlled appearance once on the wing, flight for wedge-tailed eagles can be a struggle even in normal circumstances, unless from it is from a pinnacle or it is somewhat windy and, within the forest, they may clamber about, with a "lack of grace", to reach the canopy. Gorged birds on the ground can be vulnerable, being practically grounded, which was an advantage historically to Aboriginal hunters. Human gliders have encountered wedge-tailed eagles at more than 3,000 m (9,800 ft).<p>The adult is all blackish on the wing but for the tawny-rufous nape and greyish wing band (running less than a quarter of the way down the wing's width). Little relieves the dark coloration below but the pale brown to rufous crissum and the pale greyish bases to their flight feathers. Juvenile wedge-tailed eagles appear much browner although in general are not dissimilar in pattern below though the body and wings relative to adult. However, juveniles may show some paler mottling, of an off-rufous colour. Meanwhile, the juvenile's tail and most flight feathers are barred greyish which in turn contrast against the pale based primaries with black tips. Above, the juvenile bears much paler and more sandy rufous colour from the head to at least upper mantle and along broad wing band (as well as more than half the wing width). The lighter dorsal colour sometimes extends to much of the back and scapulars. Rare individual juvenile eagles are dull black, without a wing band or paler edges. With much variation in individuals, generally as the young eagles age, the signature wing band shrinks incrementally and, after the fifth year, the plumage darkens.<p>The female wedge-tailed eagle is one of the world's largest eagles. Its nearest rival in Australia for size is some 15 per cent smaller linearly and 25 per cent lighter in weight. As is typical in birds of prey, the female is larger than the male. Although a few individual females are larger by only a small amount, they average up to 33 per cent larger. A full-grown female weighs between 3.0 and 5.8 kg (6.6 and 12.8 lb), while the smaller males weigh 2 to 4 kg (4.4 to 8.8 lb). Total length varies between 81 and 106 cm (32 and 42 in) and the wingspan typically is between 182 and 232 cm (6 ft 0 in and 7 ft 7 in). In 1930, the average weight and wingspans of 43 birds were 3.4 kg (7.5 lb) and 204.3 cm (6 ft 8 in). The same average figures for a survey of 126 eagles in 1932 were 3.63 kg (8.0 lb) and 226 cm (7 ft 5 in), respectively. <p>According to one guide, the mean body mass of male wedge-tailed eagles is 2.5 kg (5.5 lb) while that of females is listed as 4.7 kg (10 lb), which, if accurate, is one of the most extreme examples of size sexual dimorphism known in any bird of prey. However, another sample showed far less stark size differences, with 29 males weighing an average of 3.13 kg (6.9 lb) and 29 females an average of 3.8 kg (8.4 lb). In the same sample, from the Nullarbor Plain, males averaged wingspan of 193 cm (6 ft 4 in) (sample of 26) and body length of 85.2 cm (33.5 in) (sample 5) while females had an average wingspan of 209 cm (6 ft 10 in) (sample 23) and body length of 92.1 cm (36.3 in). However, the Nullarbor Plain eagles appear slightly smaller than wedge-tailed eagle sizes from other surveys, based on body mass and wing chord sizes. An average length for males of 91 cm (36 in) and 100 cm (39 in) was described for wedge-tailed eagles in Queensland. Another source claimed an average male weight of 3.2 kg (7.1 lb) and average female body mass of 4.3 kg (9.5 lb). Yet another book lists males as averaging 2.95 kg (6.5 lb) and females as averaging 3.97 kg (8.8 lb). A sample of 10 males averaged 3.14 kg (6.9 lb) while 19 females weighed 4.18 kg (9.2 lb). The mean body mass of males in Tasmania was 3.5 kg (7.7 lb) while that for females was 4.1 kg (9.0 lb).<p>The largest wingspan ever verified for an eagle was for this species. A female killed in Tasmania in 1931 had a wingspan of 284 cm (9 ft 4 in), and another female measured barely smaller at 279 cm (9 ft 2 in). Similar claims, however, have been made for the Steller's sea eagle (Haliaeetus pelagicus), which has been said to reach or exceed 274 cm (9 ft 0 in) in wingspan. Reported claims of wedge-tailed eagles spanning 312 cm (10 ft 3 in) and 340 cm (11 ft 2 in) were unverified and deemed to be unreliable per Guinness World Records. This eagle's great length and wingspan place it among the largest eagles in the world, but its wings, at more than 65 cm (26 in), and tail, at up to 45 cm (18 in), are unusually elongated for its body weight, and nine or ten other eagle species regularly outweigh it. It is around the third heaviest Aquila species, outsized only somewhat by the golden eagle and slightly by the Verreaux's eagle, although it only slightly exceeds the weight of the Spanish imperial eagle (Aquila adalberti). Among the entire booted eagle subfamily, in addition to the two heavier Aquila, it is outsized in bulk by the martial eagle (Polemaetus bellicosus), while the also long-tailed crowned eagle (Stephanoaetus coronatus) can average of a roughly similar body mass to the wedge-tailed eagle, although the latter is marginally the heavier bird. <p>The wedge-tailed is exceeded in body mass by only a few eagles, especially the Steller's sea eagle and harpy eagle (Harpia harpyja) and somewhat by the Philippine eagle (Pithecophaga jefferyi), the white-tailed eagle (Haliaeetus albicilla) and the bald eagle (Haliaeetus leucocephalus). However, it rivals the Steller's and harpy eagles and is known to be exceeded only by the Philippine eagle in total length. The wedge-tailed eagle's wingspan is the largest of any Aquila, and is exceeded amongst all eagles probably only by the white-tailed and Steller's sea eagles in average spread though its average (not maximum) wingspan is rivaled by that of the martial eagle. Among standard measurements, within the nominate subspecies, the wing chord of males may range from 553 to 667 mm (21.8 to 26.3 in) while that of the female is from 600 to 703 mm (23.6 to 27.7 in).<p>In Tasmania, the wing chord measured from 594 to 664 mm (23.4 to 26.1 in) in males and 620 to 711 mm (24.4 to 28.0 in) in females. In Nullarbor Plain, males averaged 587 mm (23.1 in) in wing chord while females averaged 638 mm (25.1 in). Other Australian wedge-tailed eagles averaged 611 mm (24.1 in) in wing chord among males and 650 mm (26 in) among females. In Tasmania, the wing chord averaged 618.8 mm (24.36 in) in males and 661.3 mm (26.04 in) in females. The extreme tail length, slightly to greatly exceeding that of other Aquila, is in males from 352 to 479 mm (13.9 to 18.9 in), averaging 370 mm (15 in) in the Nullarbor eagles and 421.2 mm (16.58 in) in Tasmania, and from 376 to 536 mm (14.8 to 21.1 in), averaging 410 mm (16 in) in Nullarbor and 448.9 mm (17.67 in) in Tasmania. Although they only slightly exceed in tail length the heavier two Aquila and crowned eagles and they can rival the tail lengths of the Philippine and the Harpiinae eagles, Tasmanian wedge-tailed eagles are quite likely to be the longest-tailed of all modern eagles. <p>The length of the tarsus may be from 99 to 139.9 mm (3.90 to 5.51 in). The tarsus of 7 males averaged 104.3 mm (4.11 in) while that of 7 females averaged 111.1 mm (4.37 in). In terms of bill measurements, the exposed culmen may range from 37.5 to 61.6 mm (1.48 to 2.43 in) in males and 46.3 to 65.1 mm (1.82 to 2.56 in) in females while total bill length (from the gape) is from 55 to 67 mm (2.2 to 2.6 in) and 58.2 to 73 mm (2.29 to 2.87 in), in the sexes respectively. It is likely to be the largest billed Aquila, a bit ahead of the imperial eagles and the Verreaux's eagle, behind only the larger Haliaeetus and Philippine eagles amongst all eagles. In Tasmania, culmen lengths averaged 48.4 mm (1.91 in) in males and 51.4 mm (2.02 in) in females while the total length of the bill averaged 59.4 mm (2.34 in) and 63.2 mm (2.49 in). <p>The hallux claw, the enlarged rear talon on the hind toe, is slightly smaller than that of a golden or Verreaux's eagle, even proportionately, but is extremely sharp. According to one study, wedge-tailed eagles had a hallux claw of 38.9 mm (1.53 in), ranging from 38.1 to 41 mm (1.50 to 1.61 in), in males 44.7 mm (1.76 in), ranging from 40.6 to 48.1 mm (1.60 to 1.89 in) in a sample of 10, in females. Another source listed the hallux claw of mainland Australian eagles as averaging 41 mm (1.6 in) in males and 46 mm (1.8 in) in females. Meanwhile, in Tasmanian eagles, the hallux claw averaged 45.2 mm (1.78 in), ranging from 38.6 to 48.8 mm (1.52 to 1.92 in) in males while in females, the hallux claw averaged 49.9 mm (1.96 in), ranging from 45.5 to 55.6 mm (1.79 to 2.19 in). In terms of osteological structure and size, the wedge-tailed eagle is said to be proportional to other eagles, being notably smaller and less robust than the heaviest eagles, such as Steller's and harpies, but fairly similar in osteology, in both structure and proportions, to the golden eagle.<p>Their unique combination of large size, lanky build, long, diamond-shaped tail (though can be round-ended when both central feathers are moulted together), mainly black or rather dark plumage, and long wings seen when soaring or gliding make all ages of the wedge-tailed eagle fairly unmistakable in the majority of their range. The only main confusion species is often the black-breasted kite (Hamirostra melanosternon), which is surprisingly similar in colouring but is much smaller with a relatively short, squared tail and extensive clear white windows covering a good part of their wings. Juveniles of the white-bellied sea eagle (Haliaeetus leucogaster), at times mentioned as potentially confusable with a young wedge-tailed eagle, are much paler below with a rather different flight pattern: a short pale tail, bare legs, shorter, broader wings held in stiff dihedral.<p>In New Guinea, the Gurney's eagle is more similar than those species in form and build but the Gurney's is somewhat smaller and more compact than the wedge-tailed eagle with rich yellow feet, a rather shorter rounded or faintly wedge-tipped tail, shorter and relatively broader wings (in adaptation to more forest-living). Furthermore, the Gurney's eagle has a much paler immature plumage. Although usually considered an island endemic, the Gurney's eagle is possibly capable of marine dispersals, as is the wedge-tailed eagle, that may lead to them to turn up in the forests of northern Australia and historical reports show that a rare vagrant of the species may indeed appear there. The Papuan eagle (Harpyopsis novaeguineae), the only other island raptor in New Guinea that approaches the wedge-tailed in size, is a highly distinct and forest-restricted species, being much paler, particularly below, with long, bare legs and different proportions, more like a giant Accipiter with short rounded wings, a long, somewhat rounded tipped tail, and a large, rounded head.<p>Wedge-tailed eagles are not well known for its vocalization nor are they often heard. They may be silent for long stretches of time, possibly months, at least outside of breeding season. When vocalizations have been documented, it usually only near the nest and in aerial display, and can be hard to hear unless at close range. The commonest calls for wedge-tailed eagles are high, rather thin whistles, sometimes transcribed as I-see, I-see followed by a short descending see-tya. Also documented during the breeding season are various other whistles, yelps and squeals and an often rolling series. Characteristically, all their calls are surprisingly weak, though the main call is sometimes considered to have a "melancholy" quality. The opinion on their call is not dissimilar to the golden eagle, whose voice is similarly considered unimpressive. Female calls in wedge-tailed eagles are similar but are generally lower and harsher than males.

Taxonomie

The species was first described in 1801 by the English ornithologist John Latham, under the binomial name Vultur audax. At one time, the wedge-tailed eagle was classified in it is own monotypical genus Uroaetus, perhaps due to its unique form.<p>Today, the genus Vultur is used only for a completely unrelated bird of the New World vulture family, the Andean condor (Vultur gryphus). The specific scientific name for the species, audax, is derived from the Latin audax, meaning "bold", indicative of their perceived disposition, perhaps when hunting, although the species is, in general, highly wary, and even timid, around humans.<p>However, the species is quite similar in many aspects of its morphology, appearance, behaviour and life history, to other species in the Aquila genus. The eagles of the Aquila genus are part of the subfamily Aquilinae, within the larger Accipitridae family. The subfamily is commonly referred to as booted eagles or sometimes as true eagles. Those species may be distinguished from most other accipitrids by the feathering covering their legs, regardless of distribution. With some 39 or so species, the Aquilinae is present on every continent except Antarctica.<p>By a variety of phylogenetic testing, largely via Mitochondrial DNA and Nuclear DNA genes, it has been determined that the wedge-tailed eagle clusters with certain other Aquila eagles. The species found to share the most genetic similarities is the Verreaux's eagle (Aquila verreauxii) of Africa. However, the Gurney's eagle (Aquila gurneyi), a mostly allopatric but outwardly fairly similar eagle, is clearly a very close relation of the wedge-tailed eagle and the two are likely sister species, most probably originating from the same radiation across the Indo-Pacific region.<p>The wedge-tailed, Gurney's and Verreaux's eagles form a clade or a species complex with the well-known golden eagle (Aquila chrysaetos), the most widely distributed species in the entire accipitrid family, as well as outwardly dissimilar (smaller and paler-bellied yet also powerful) eagles like the Bonelli's eagle (Aquila fasciata), the African hawk-eagle (Aquila spilogaster) and the Cassin's hawk-eagle (Aquila africanus), the latter three having once been considered members of a different genus.<p>Beyond the aforementioned species, based on genetic testing, the four other Aquila species, although outwardly similar to golden and wedge-tailed eagles, being large, dark and brownish, with long wings, are thought to form a separate clade, and are paraphyletic from the members of what can be called the golden eagle clade. Other related outliers from outside the Aquila genus, are the small-to-mid-sized Clanga or spotted eagle species, and the widely found and quite small Hieraeetus eagles. One member of the latter genus contains the only other widely found Aquilinae eagle in Australia, the little eagle (Hieraaetus morphnoides).<p>Two subspecies of wedge-tailed eagle are recognised. However, the separation of the two subspecies has been called into question, largely because the reported differences in both size and coloration can be attributed to clinal variation and some of the insular populations may still be at an intermediate stage of subspecific formation.

Wissenschaftlicher Name

Aquila audax

Autorität

(Latham, 1801)

Ordnung

Accipitriformes

Familie

Accipitridae

Gattung

Aquila

Verbreitung und Lebensraum

Wedge-tailed eagles are found throughout Australia (including Tasmania), as well as southern New Guinea, in almost all habitats, though they tend to be more common in favourable habitat in southern and eastern Australia. In Australia, they may be found almost all the way from the Cape York Peninsula in the north down to Wilsons Promontory National Park and Great Otway National Parks in the southern tips of the continent, and from Shark Bay in the western side of the continent to Great Sandy National Park and Byron Bay in the east. They are widespread throughout the desert interior of Australia, but are rare in low densities in the most arid parts of the continent, such as the Lake Eyre Basin. Offshore, the wedge-tailed eagle may be distributed in several of the larger Australian islands and some of the smaller ones. Those include a majority of the Torres Strait Islands, Albany Island, Pipon Island, the isles of Bathurst Bay, many small isles in Queensland, from Night Island down to the South Cumberland Islands, Fraser Island, Moreton Island, North Stradbroke Island, Montague Island, Kangaroo Island, the Nuyts Archipelago, Groote Eylandt and the Tiwi Islands. In Tasmania, they may be found essentially throughout as well as some isles of the Kent Group, Bass Strait, Flinders Island and Cape Barren Island. In New Guinea, the wedge-tailed eagle is highly range restricted and can be found predominantly in the Trans-Fly savanna and grasslands and the general area around the Western Province, as well as in Indonesia Merauke Regency, with some isolated reports in Western New Guinea, the Bensbach River and the Oriomo River.<p>The wedge-tailed eagle lives in an extremely wide range of habitats. Although range is restricted relative to the golden eagle, it likely occupies a wider range of habitat types than likely any other Aquila eagle, and may outrival any booted eagle species in their use of diverse habitats, being somewhat more akin to habitat generalist raptors such as Buteo buzzards. Assorted habitats known to host wedge-tailed eagles includes open woodland, savanna, heathland, grasslands, desert edge and semi-desert, subalpine forests, montane grasslands and mountain peaks, not-too-dense tropical rainforests, monsoon forests, dwarf conifer forests, some wetlands as well as regularly forays to coastal areas, though normally along the coasts they occur around plains somewhat away from the water. Favored habitat tends to be remote or rough country, at least partially wooded and not uncommonly varied with some rocky spots as well as in shrubland. Wedge-tailed eagles seem to prefer some dead trees to be present. They may occur around Eucalyptus woodland quite regularly, as well as Acacia woodland and mixed woodlands of Casuarina cristata-Flindersia maculosa-Callitris cypresses and also stands of Casuarina cunninghamiana. A strong preference was detected for C. cunninghamiana alternatively with several Eucalyptus species was detected in the Australian Capital Territory, sloping ground allowing good access and access to tall, mature trees being paramount to the eagles in the study. Quite often they will be seen soaring over hills, mountains or escarpments as well as over flat plains, especially spinex grassland. Dense forest is typically avoided with glades and edge often sought out in forested areas. While they do occur in rich riparian woodlands, it is with relative scarcity despite this being where many other raptors of the nation concentrate. In the deserts of the Lake Eyre basin, they are often seen in gibber plains along treed watercourses and drainage basins, here often concentrated around Eucalyptus in stony creek beds. In the sandy desert areas of Western Australia, wedge-tailed eagles were once reasonably common but have largely vacated the region after the macropod prey they live off of there were all but hunted to extinction. Wedge-tailed eagles commonly occur from sea level up to about 2,000 m (6,600 ft) with seemingly no preference based on altitudinal level. A fairly pronounced liking for mountainous localities such as plateaus has been detected in a few studies of wedge-tailed eagle. One of the few habitat types considered to be strongly avoided by wedge-tailed eagles are areas intensively settled or cultivated areas. A slightly fading tendency to avoid human areas has been detected, perhaps as persecution rates have gone far down, and the wedge-tailed eagle may be seen near towns and villages in exurban and even suburban areas largely within bushland. However, the species is seldom seen other than as a flyover in more developed towns and cities. Additionally, it is not uncommon to see these eagles in man-made spots such as pasture areas, forestry clearings, and rolling farmland areas.

Zugverhalten

Resident species

Verhalten

This impressive bird of prey spends much of the day perching in trees, on rocks as well as similar exposed lookout sites such as cliffs from which it has a good view of its surroundings. Alternatively, they may sit on the ground for long periods of time or watch from a lower point, such as or termite mounds or anthills. Now and then, it takes off from its perch to fly low over its territory. Especially whilst not breeding, wedge-tailed eagles spends a considerable amount of the day on the wing. Wedge-tailed eagles are highly aerial, soaring for hours on end without wingbeat and seemingly without effort, regularly reaching 1,800 m (5,900 ft) and sometimes considerably higher. The purpose of soaring has received little specific study in wedge-tailed eagles, but it is likely, as in other accipitrids, in large part for surveying the territory and advertising their presence to other eagles. During the intense heat of the middle part of the day, it often soars high in the air, circling up on the thermal currents that rise from the ground below. Often when on the wing, it is scarcely visible to the human's naked eye. Their keen eyesight extends into ultraviolet bands. With a visual perception some three times more acute than those of humans, one of the largest pecten oculi of any bird and an eye roughly as big as a small human's, they may be one of the most sharp-eyed birds in the world. <p>The wedge-tailed eagle is largely sedentary as expected of a raptor dwelling in the subtropics, although they also dwell in the tropics (far northern Australia and New Guinea) as well as in the temperate zone (Tasmania). However, juveniles of the species can be quite dispersive. In some cases, they have moved to a recorded distance of some 836 to 868 km (519 to 539 mi). These extreme movements have been completed within 7 to 8 months after dispersal. More typically they move no farther than 200 km (120 mi) or so. The adult eagles can also be nomadic, though only in circumstances such as drought conditions. In turn this explains the species presence in places they don't breed, even adults. In addition to moving for drought in arid zone, also moves in highest part of New South Wales, e.g. the Snowy Mountains, the species often apparently vacates snow-covered alpine zone in winter. The small New Guinea population is apparently indistinguishable from the mainland race and so possibly result of recent colonization, although no records exist of migrating wedge-tailed eagles islands past the Torres Straits. However, it can be projected from its presence in various offshore islands its capacity for crossing straits ranging up to as far as 50 to 100 km (31 to 62 mi) apart. One post dispersal young eagle was observed to distribute from Kangaroo Island to the mainland, possibly a regular occurrence. Due to their tendency for wandering, some authors class the wedge-tailed eagles as a “partial or irruptive migrant”. However, while they are arguably irruptive, it does not fit the mould of a true migrant well since under normal circumstances adults are rather sedentary unless environmental changes force them to move.<p>The wedge-tailed eagle is the only bird that has a reputation for not infrequently attacking hang gliders and paragliders, although other eagles including the golden eagle have also been recorded to behave thusly. Based on the response the eagles show to the gliders, they presumably are defending their territory and treating the perceived intruder like another eagle. Cases are recorded of the birds damaging the fabric of these gliders with their talons as well as some other parts of the gliding apparatus, but not the humans themselves, has been reported. They have also been reported to attack and destroy unmanned aerial vehicles used for mining survey operations in Australia. <p>The presence of a wedge-tailed eagle often causes panic among smaller birds and, as a result, aggressive species such as magpies (one of the most vulnerable types of passerine to eagle attacks), butcherbirds, wagtails, monarch flycatchers, lapwings, and miners as well as smaller birds of prey, including both accipitrids and falcons, any of which may aggressively mob eagles (see video). Multiple species may join the kerfuffle and mob them, especially while the eagles perched, often engaging in noisy calling, presumably meant to disorient the predator, and occasionally in physical attacks against the eagle, typically focused where the big, relatively lumbering eagles could not grasp the attacking birds. The wedge-tailed eagle usually does not engage its tormentors but sometimes rolls in the air to present talons whether perched or not. Sometimes wedge-tailed eagles appear to fight but this and other behaviours, especially between young eagles, may be interpreted as playful. Some such behaviours have included fetching sticks tossed by others, athletic flipping between juvenile eagles and even playing games with dogs, via floating above them until the dogs bark or leap then floating up until the dog settles and then repeating the “game”.<p>Flocking behaviour has been noted, similar to that of vultures (Cathartidae and Accipitridae) in other countries, when carrion is available.

Schutzstatus

In the 1990s, it was estimated broadly that the global population was somewhere between 10,001 and 1,000,000 individuals. As of 2009, Birdlife International listed the total population as only 100,000 mature individuals, possibly conservative and from admittedly poor supporting data. As of that analysis, Birdlife considers the overall population of wedge-tailed eagles to be “possibly increasing”. Generally, the wedge-tailed eagle appears to be quite stable in population. Although wedge-tailed eagles are often scarcer than those large distribution suggests, their total distribution covers more than 10.5 million square kilometres and the population is quite likely within hundreds of thousands. Thinning of forest cover, mostly inadvertent provisioning of carrion food sources and, particularly, rabbit introductions may have aided the species, and it may actually be commoner now than before European colonization. Though protected, sometimes wedge-tailed eagles are shot or trapped or killed by poison carcasses set out by farmers many of whom consider it a serious sheep killer. Historically, the wedge-tailed eagle was subject to persecution levels to rival any other eagle in the world. The heavy persecution began in the closing decades of the 19th century, due largely to the establishment of large-scale sheep farming in Australia. One Queensland station claimed to have poisoned 1060 eagles over 8 months in 1903. <p>Laws passed from 1909 to 1925 made it mandatory for landowners and farmers to kill eagles as vermin with enforcement determined by a given region's minister or vermin board, resulting in even more sweeping efforts to destroy the species. Steel-jawed rabbit traps were set around carcasses and Heligoland traps could sometimes trap several eagles at once, beyond sustained shooting and poisoning efforts. Between the years 1958 and 1967, 120,000 bounties were paid in merely the states of Queensland and Western Australia on wedge-tailed eagles killed, meaning an average 13,000 were killed each year. Even by 1967 to 1976, likely intentional human killings accounted for 54% of wedge-tailed eagle mortalities in Western Australia, with an estimated 30,000 killed in the year of 1969 throughout Australia. Strong legal protections started in Western Australia in the 1950s increasingly so to the 1970s or later elsewhere, now it is protected and subject to limited persecution throughout. Despite reduced persecution, as of the 1980s, 54% of recovered eagles by the 1980s were killed by human persecution. Despite such stunningly high rates of persecution, the wedge-tailed eagle was remarkably resilient to the haphazard persecution inflicted by humans in a way many other Australian wildlife, especially the regionally endemic mammals, and even other eagles elsewhere often are not.<p>Often the species is less intentionally harmed via human disturbance via land development particularly intensifying agricultural and modern settlements, which can in turn lead to clearing of mature trees, disturbances at the nest and decline of native prey species, all of which have a net negative effect on the wedge-tailed eagles. Eggshell thickness was not significantly decreased by the use of DDT likely due likely to the largely mammal-based diet of the species, whereas raptors which consume birds or fish are disproportionately effected by DDT. On occasion, the species is still subject to illegal shootings and poisonings, however persecution of the species is significantly less prevalent in recent decades. Occasionally but not commonly, they are killed by sodium fluoroacetate poisons long used to “control” Australian wildlife, but now generally directed at invasive species such as rabbits, feral pigs and foxes. A list of the main persistent threats in the 21st century to wedge-tailed eagles consists of: destruction of habitat, including logging, developments including urbanization, wind farm collisions and the disturbance and destruction associated with their construction, increasing density rural human populations, illegal persecution in sheep farm areas, drowning in open tanks in dry pastoral zones, roadkills (especially while foraging for roadkill carrion), collisions with fences, powerlines and airplanes, regular electrocutions, poisoning from rabbit baits and other baits and exposure to lead and other bullet fragments which may be responsible for some eagle debilitations and deaths. Within the Fleurieu Peninsula, some 1.74 eagles on average are claimed by wind farm turbine collisions. <p>Conservation needs may differ in different habitats, i.e. in more coastal temperate areas, the eagle is reported to have difficulty nesting when hillsides have been cleared of trees, meanwhile inland, they have lesser need of trees in elevated locations because they are more often assisted by thermals. However, they cannot generally persist where leafy trees are clearcut. Surprising resilience even to drought was found recently in the wedge-tailed eagles in the Australian Capital Territory where pair occupancy remained consistent through drought for wedge-tailed eagles but not for little eagles, but this is may have more to do with the wedge-tails more successful uncoupling from a dependence on declining rabbits as prey than the little eagle. Of 84 eagle deaths or debilitating injuries, 52% were attributable to collisions or electrocutions, 15.5% due to persecution, 11% due to natural causes and 15% were due to unknown causes. <p>The Tasmanian race of wedge-tailed eagle, A. a. fleayi, is quite restricted in range and habitat, with estimated numbers having gone from 140 pairs in the 1980s down to only 60–80 by the mid-1990s. With the island's population numbering quite low and likely continuing its declining, as evidenced by slow replacement of lost pair members, the subspecies is listed as state-endangered. Furthermore, surveys contrasting 1977–1981 with 1998–2001 data found a decline of around 28% in the island's reported number of eagles. Generally Tasmanian wedge-tailed eagles are even less tolerant of human alterations and disturbances near the nest site than mainland wedge-tailed eagles and have more specific habitat requirements. Historically, the same hunting organization in Tasmania that played a large role in the extinction of the thylacine (Thylacinus cynocephalus) also intentionally tried to hunt the Tasmanian wedge-tailed eagle into extinction, publicly having erroneously claimed that eagles were non-native in Tasmania; however, hunting is unlikely to further continue on a large scale in the state. Where habitat clearance and degradation is extensive in Tasmania, the native prey populations are insufficient to support eagles. Furthermore, the clearing or logging of trees is especially critical in Tasmania, where the eagle is by and large a forest-dependent breeder. <p>Studies indicate that Tasmanian eagles mostly nest in emergent trees in old-growth native forest exposed to early morning sun and sheltered from prevailing strong winds and cold spring winds, given the more temperate climate there relative to most points in mainland Australia. The subspecies requires forest areas greater than 10 ha (25 acres) in which to breed and is very prone to desert its nest when disturbed. A predicted change was calculated to the carrying capacity of the Tasmanian forest given current operations is modeled, likely driving the population down. Wind farms in Tasmania are also an occasional threat; although not thought to be a significant source of mortality, wedge-tailed eagles, especially young ones, are less success at avoiding invariably fatal collisions with them than Tasmanian white-bellied sea eagles. Furthermore, of 109 eagle carcasses recovered in Tasmania, all of them had trace levels of lead in their livers or femurs with at least part of the exposure likely from lead ammunition. In addition, like all eagles, Tasmanian wedge-tailed eagles are vulnerable to electrocutions, and collisions with vehicles, overhead wires, and fences and poisonings, largely via illegal killings by poachers of Tasmanian devils and forest ravens (Corvus tasmanicus). Efforts are underway to ameliorate the harm being done to Tasmanian wedge-tailed eagles, especially via forestry operations. <p>In protected areas, protocols are in place to protect Tasmanian eagle nests and protect them by creating an obligatory nest reserve of at least 10 ha and forestry operation have been restricted during the breeding season to outside a buffer zone of 500 m (1,600 ft), extending further to 1 km (0.62 mi) if the proposed work is in the line-of-sight of the nesting eagles. About 20% of known pairs are outside protected areas and on private land, so are largely outside the strict legal protection the subspecies has on governmental forest land. Furthermore, researchers are instituting rules to minimize disturbance, limiting breeding surveys to distant observations of whitewash and flattened treetops as proof of nesting and all detailed observations to be obtained after the cessation of breeding activities.

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