Steppenadler

Bestimmung

The steppe eagle is a large, bulky and robust-looking eagle. It is mainly dark brown in colour with a longish but very thick neck and a relatively small head that nonetheless features a strong bill and long gape-line. It appears long-winged and has a longish and rather rounded tail and markedly well-feathered (almost with disheveled looking feathers) legs. Steppe eagles tend to perch somewhat upright and usually do so in the open, often utilizing isolated trees, posts, rocks or other suitable low lookouts such as mounds or straw-piles. The species often is seen on the ground where may stand for long periods of the day and walk with horizontal posture and with wingtips just exceed the tail-tip. Steppe eagles, like tawny eagles, can be relatively tame and approachable, at least compared to many of the other Aquila eagles. The adult is a somewhat variable brown with darker centers to the greater coverts. More pronouncedly in the eastern part of the range, adults have normally prominent pale rufous to dull orange-yellow to yellow-brown patches on the nape and hindcrown. Any other paler areas (such as the feather tips of the back and uppertail coverts) are obscured on perched adults. The massive gape-line runs to level with the rear of eye (further emphasized by dark border against paler chin) and is longer than in any other Aquila eagles including tawny eagles. Combined with their deep-set eyes, it lends steppe eagles an altogether rather fierce facial expression. Steppe eagle juveniles are almost invariably paler than adults, with some ranging overall from umber-brown to tawny-buff but then some are darker and more deeply brown. Juveniles tend to be brown to grey-brown on the upperparts but for generally rufous-buff nape patch (more so on eastern population). The juveniles bear conspicuously and broadly white-tipped black about the greater coverts, wings and tail and a bold but narrow cream band on the brown medians. The juvenile steppe eagle's white uppertail coverts is generally concealed when perched; the underparts are usually the same as the upperparts but may be somewhat paler tawny-buff hue. Upon their 2nd year, the plumage is still much as the 1st year appearance but show the pale tips to secondaries, median coverts and tail as often well-worn and narrower; by the start of 2nd winter the, tips of retained juvenile flight-feathers and coverts are heavily abraded and very thin. By the end of 2nd winter, often the immatures look very worn and have nearly lost pale tips altogether and from 3rd year onward manifest a variable mix of old and new feathers. Generally, immatures are often rather scruffy in appearance until adult-like plumage attained at year five, after which the feathers generally appear more compact. Adults have brown to hazel eyes, while juveniles have distinctly dark brown eyes; the cere and feet are yellow at all ages.<p>In flight, the steppe eagle appears as a large, impressive and visibly heavy raptor with a well-projecting large head and bill and rather broad neck and long, broad wings. They evidence proportionately long arms, especially in the larger eastern birds. The wings tend to be held almost parallel-edged and square-ended with 7 very elongated emarginations. Often juveniles can tend to appear somewhat narrower winged. The broad body of the species often looks suspended underneath and the tail appears rounded or even wedge-shaped, measuring about 3/4 of the length of wing-base. The wingspan is about 2.6 times greater than the total body length. On the upperwings, steppe eagles show a pale greyish primary patch that is often quite large and obvious (especially on non-adults), often being pale at the base on the greater primary coverts but on adults (especially dark birds) much less marked. On the underwing, a very small carpal crescent may be present but can vary from invisible to slightly more marked. The flight feathers are greyish and all have 7–8 well-spaced blackish bars (albeit less conspicuously than on spotted eagles), while the fingers are plain blackish. Adults are basically all fairly uniform dark brown (wings can be negligibly greyer or rarely yellowish brown). Adults may evidence in flight some whitish patches on back and tail coverts that are varying from insignificant to fairly prominent. Adult eagles that do show a dark-barred greyish primary patch usually have that confined to a wedge-shape on inner primaries though can sometimes be rather more prominent. Below adults show dark-barred grey flight feathers and tail with the broad blackish trail edges and wing ends being rather distinctive; the wing linings are often slightly paler to darker than remiges and often with an obscure remnant of broken paler central band. Juveniles are quite distinctive in flight if seen in reasonable view. Above, juveniles are pale greyish-brown to yellow-brown about the body and forewing-coverts, have a broad whitish U above the tail. They possess broad white tips to the blackish greater coverts, flights feathers and tail creating obvious whitish bars on the wings and trailing edges as well as a large and prominent whitish patch covering much of the inner primaries (causing barring to stand out more so and offsetting plain black wing end). On its underside, the juvenile is mid-brown to brownish-yellow with a paler throat and creamy crissum. Below, the creamy central wing band is even broader than above, while the greater coverts all white with some dark centres on primaries (rare extreme pale individuals appear to have almost uniform paler colour on the entire wing lining and lesser and medians buffish-white to pale sandy, often whitish pale primary-wedges). Despite reports that some juvenile 1st years have subtle or no central wing bands, these are believed to be cases where these feathers exist but are obscured by long median coverts. At the end of the first year, the young steppe eagle tends to have pale tips to wings, tail and upperwing coverts become rather abraded; thereafter the development young evidence much variation due to individual differences. Usually, by the end of 2nd winter, the wing looks even more worn and uneven in pattern, with any newly acquired narrowly white-tipped quills clearly longer than old worn juvenile ones that have lost their pale tips. From the 3rd winter on, the pale parts clearly reduced, flight feathers and tail often appear quite ragged and by the 4th year start to more resemble adults. From the end of the 3rd year to when they obtain adult plumage, the eagles tend to have adult-like broad blackish trailing edges and tail often coupled with dark-barred grey base to black fingers and traces of the pale band along greater underwing-coverts. Maturity is obtained between the 4th and 5th years, not at 6–7 years as previously reported despite some presumed five-year-old eagles still have flecks of pale on the wing coverts and the throat and more subtle nape patches than they will ultimately manifest.<p>The steppe eagle is large and impressive raptor and quite a large eagle. However, as a member of the genus Aquila, it is fairly medium-sized. Females can range to 15% larger with greater dimorphism by weight, which is more pronouncedly dimorphic than by linear dimensions. Total length can range from 60 to 89 cm (24 to 35 in) in fully-grown steppe eagles. Wingspan in full grown eagles of this species is very variable, with the smallest steppe eagles spanning as little as 165 to 174 cm (5 ft 5 in to 5 ft 9 in) while the largest ones can reportedly span up to 250 to 262 cm (8 ft 2 in to 8 ft 7 in). Although some sources list the maximum wingspan as only 214 or 216 cm (7 ft 0 in or 7 ft 1 in), the maximum wing dimensions were apparently confirmed for the most massive steppe eagles (i.e. from Altai). Body mass, like wingspan, as reported is also fairly variable. Steppe eagles weighed for a Russia handbook were found to scale from 2.5 to 3.5 kg (5.5 to 7.7 lb) in males while in females weights reported to range from 2.3 to 4.9 kg (5.1 to 10.8 lb). Elsewhere, the minimum full-grown weights for smaller western eagles (formerly subspecies A. n. orientalis) were 2 kg (4.4 lb) for the smallest males while the heaviest females were found to have attained a weight around 3.9 kg (8.6 lb), while weights in the eastern part of the breeding range are around 20% heavier. In one sample of steppe eagles of possibly varied origins, males weighed a mean of 2.48 kg (5.5 lb) and females a mean of 3.56 kg (7.8 lb). Wintering eagles of the species in southern Africa weighed a mean of 3.02 kg (6.7 lb) in a sample of four. In Saudi Arabia, 21 steppe eagles at one study site weighed a mean of 3.28 kg (7.2 lb) while 27 eagles at another study site there weighed a mean of 3.45 kg (7.6 lb). Unpublished weights from Israel were much lower at a reported mean of 2.11 kg (4.7 lb), as in other raptors during passage migration in Israel, weight loss may be significant relative to the other seasons. Steppe eagles diagnosed as from the smaller-bodied, western part of the breeding range weighed a mean of 2.46 kg (5.4 lb) in 13 males and a mean of just under 3 kg (6.6 lb) in a sample of 18 females while the mean weight of larger, eastern breeding bird was listed as 3.01 kg (6.6 lb) in 2 males and 3.57 kg (7.9 lb) in 2 females. The maximum cited weight for steppe eagle males in the wild is 4.6 kg (10 lb) while that for females is 5.5 kg (12 lb). Among standard measurements, the wing chord can measure from 510 to 610 mm (20 to 24 in) in males and from 536 to 640 mm (21.1 to 25.2 in) in females. The tail may measure from 238 to 295 mm (9.4 to 11.6 in) in both sexes and the tarsus may be from 85 to 96 mm (3.3 to 3.8 in) in males and from 92 to 98 mm (3.6 to 3.9 in) in females, both fairly short for the size of the eagle (although its cousin fossil speciea, A. nipaloides, was apparently even shorter legged). Wing chord length averaged 536 mm (21.1 in) and 566 mm (22.3 in) in males and females in a study, respectively. The huge gape of a steppe eagle is from 49 to 60.8 mm (1.93 to 2.39 in) wide, with an average of 53.1 and 55.3 mm (2.09 and 2.18 in) in males and females, respectively, while the gape length is 40 to 49.7 mm (1.57 to 1.96 in), averaging 44.3 and 45.8 mm (1.74 and 1.80 in) in the two sexes. The hallux claw, the enlarged killing talon on the rear foot of essentially all accipitrids measures from 28.3 to 36.8 mm (1.11 to 1.45 in), averaging 33.8 mm (1.33 in), in males from 31.8 to 40.5 mm (1.25 to 1.59 in), averaging 36 mm (1.4 in), in females. As in the tawny eagle and imperial eagles, the talon size is modest, whereas most species in the golden eagle clade are markedly larger clawed relative to their size.<p>In many circumstances, the steppe eagle can be very difficult to distinguish from other similar eagles, often especially during passage and winter. Adults are often confused with spotted eagles but are best separated by their much more broad build, far greater wing areas with longer, more rectangular or squarish wing tips and longer, more conspicuous fingers, larger head (rather than small and bull-headed) and larger overall size. Compared to the spotted eagles, the flight of the steppe eagle is more aquiline, i.e. more powerful, labored and deep while spotted eagles tend to fly more like buzzards. The lesser spotted eagle (Clanga pomarina), the most similarly marked of spotted eagles, is particularly less powerful looking with a shorter neck, much smaller wing areas, shorter fingers and tail and less extensive, baggy leg-feathering. The greater spotted eagle (Clanga clanga) is also smaller and slighter but to a reduced extent. When plumage is clear to see, steppe eagles have more clearly and more extensively barred quills and lack the clear carpal arcs of the two widespread spotted eagles but these differences are obscured at greater distances. Some subadult steppe eagles, with their paler brown wing-coverts above and below and only traces of white underwing bands and clearly pale primary patch above in particular quite resemble the plumage of older lesser spotted eagles. The white wing bars of steppe eagles are usually more conspicuous than those of the lesser spotted eagle. At close range, the steppe eagle has a deeper gape than lesser and greater spotted eagles and has rounded rather than oval nostrils. When seen perched, either on a perch or on the ground, spotted eagles of all three species tend to stand quite tall and upright, emphasizing their more slender and lightly feathered legs, while the steppe eagle sits more horizontally and is always far bulkier than even the biggest greater spotted eagles. Some particularly dark adult and subadult steppe eagles with obscured paler wing feathers can greatly resemble adult greater spotted eagles (the latter species can appear almost blackish in certain lights) and would need to be identified by the differences in size and form. The Indian spotted eagle (Clanga hastata) has a deep gape reminiscent of the steppe eagle but is much slighter in overall size, being similar in size or even smaller than a lesser spotted eagle, and has even less conspicuous whitish wing markings than the lesser spotted. As a result of their rough similarities, many young steppe eagles are misidentified, particularly from a distance, with spotted eagles although generally, identification is possible via a combination of structure and plumage features. Juvenile steppe eagles are normally readily identified by distinctive plumage features but can recall juvenile eastern imperial eagles, the latter has a longer and less rounded tail, a more prominent (rather than deeply set) bill, has a much paler and more buff overall colour while the chest is overlaid with brown streaking and the quills are unbarred. Imperial and steppe eagles are often similar in size, with more western breeding birds usually being somewhat smaller when seen side by side with an imperial eagle and the eastern steppe eagles being of similar average size (but even larger maximum size) compared to full-grown imperial eagles. Steppe eagles are told from tawny eagles by that species being smaller and less bulky with shorter wings, a smaller gape, a more slender neck and a relatively longer tail. Both the tawny and steppe eagle tend to have a distinct S-shape curvature to the trailing edge of the wings. When perched on the ground, the tawny eagle tends to stand more upright, while the steppe eagle often appears to assume a more elongated, horizontal posture. Plumage variations of tawny eagles can render them a surprisingly close colour to the usually darker, duller and browner steppe eagle (especially so in south Asia), but they never obtain the distinct whitish wing band of the young steppe eagle nor the nape patch of most adult steppes. Despite slight individual and clinal variations, the steppe eagle, unlike the tawny eagle, is not polymorphic. These aforementioned eagles present the main possibilities for confusion, less likely mistakes can potentially range from relatively dainty and much smaller Wahlberg's eagles (Hieraeetus wahlbergi) (generally quite different in features but somewhat similarly hued) in Africa to the somewhat bigger but differently structured golden eagles (much longer tail, relatively smaller bill and much smaller gape, different wing shape, more aquiline build and bigger feet and talons) in much of the range.

Taxonomie

British naturalist Brian Houghton Hodgson described the steppe eagle in 1833. Aquila is Latin for "eagle" while nipalensis means "from Nepal" based on the location where the type specimen was collected presumably while migrating. Samuel G. Gmelin however described a species of eagle from Tanais where they were found sitting on ancient mounds or graves of nomads. He called it Aquila mogilnik, the species name "mogilnik" meaning burial in Russian. This was included in the 13th edition of Systema Naturae by his cousin J.F. Gmelin in 1788. The identity of this bird was however confused with A. heliaca but research in 2019 suggests that A. mogilnik can reliably be identified and that it would have been a valid senior name for A. nipalensis had it not been declared as a nomen dubium, a doubtful name by Ernst Hartert in 1914. The lack of usage of the name in literature now makes the name nomen oblitum, a valid senior name lost by disuse. The steppe eagle is a member of the booted eagle subfamily within the Accipitridae family. The booted eagle clan are monophyletic and study of karyotypes has indicated that they likely have few to no close external relations within the overall extant accipitrid family. The booted eagle subfamily all have feathers covering their legs and may be found to some extent on every continent that contains accipitrids. The genus Aquila has been thought to traditionally composed of by large and fairly dark eagles that generally habituate to various open habitats. However, a significant division was determined to exist between superficially similar eagles such as the golden eagle (Aquila chrysaetos) and its three extant and similar-looking close cousins, as well as three very different smaller and pale-bellied eagles (the Bonelli's, African hawk- and Cassin's hawk-eagles) and the species complex which contains the steppe eagle. There is a similar genetic disparity with the golden eagle for the steppe eagle as with the spotted eagles which have been deemed distinct enough to form a separate genus, Clanga. The steppe eagle genetically clusters closely to the tawny eagle as well as, albeit more distantly, with the eastern (Aquila heliaca) and Spanish imperial eagles (Aquila adalberti). However, the loci evidenced in the Aquila genera have been found to be relatively homogenous, with general studies of isoenzymes showing their genes as about ten times less distanced than certain owl genera.<p>The steppe eagle has historically been considered conspecific with the tawny eagle, even until as recently as 1991. The latter species resides year-round in the African and Asian areas often used seasonally as wintering grounds by steppe eagle. The species were ultimately separated on the grounds of the differences in morphology, disparate coloring, distinct life histories and behaviours. Testing of genetic materials has reinforced the species distinction of the steppe and tawny eagles. Genetically, the steppe eagle is thought to be basal to related species such as the tawny and imperial eagles. A fossil species, Aquila nipaloides, has been found in Italy, Corsica, Sardinia and France and was hypothesized to most closely related to the steppe eagle based on osteology of the ramus (although did evidence some differences in leg morphology). Despite being even more strongly distinctive from the steppe eagle than the tawny eagle, the eastern imperial eagle has been seen to hybridize with the steppe eagles in the wild, once in Turkey and at least three times in Kazakhstan. Each hybrid with imperial eagles has been known to involve pairs of subadult or juvenile eagles and all known hybrid pairings were between male steppe eagles (or apparent steppe-imperial hybrids themselves) mated to female imperial eagles. Some of these hybrid pairs also produced seemingly healthy young with roughly intermediate characteristics.<p>The steppe eagle has been generally considered to contain two subspecies. One was the nominate subspecies, A. n. nipalensis, which breeds in the eastern portions of the range (perhaps from the East Kazakhstan Region to all points east) while the western breeding population, found in most of Kazakhstan and European Russia, was considered as the subspecies, A. n. orientalis. The separation of two subspecies was largely based on size, with the eastern population being larger and much heavier than the western eagles. The more eastern birds tend to be a shade darker and a have a more extensive nape patch, as well as having a more conspicuously deep gape-line. However, both western and Russian researchers have since made a convincing advocacy that the steppe eagle is actually a monotypical species. It was found that both previously claimed subspecies appear to broadly overlap in the breeding range and become indistinguishable at the Kazakh-Russian meeting point. The primary differences, i.e. in size and mildly in colour, can be explained as clinal variations due to the environment. The breeding populations of the eastern and western eagles are insufficiently allopatric and too extensively engage in introgression to be properly regarded as full subspecies. Erroneously, a checklist once included the former subspecies of A. n. orientalis as being part of the subspecies of tawny eagle from Asia, A. r. vindhiana, an error that was later corrected.

Wissenschaftlicher Name

Aquila nipalensis

Autorität

Hodgson, 1833

Ordnung

Accipitriformes

Familie

Accipitridae

Gattung

Aquila

Verbreitung und Lebensraum

Although the breeding range is rather extensive, the steppe eagle is essentially confined to nesting in only four large nations: Russia, Kazakhstan, Mongolia and China. However, the steppe eagle once bred in Europe. Here, they bred into the 20th century in at least southeasternmost Ukraine and perhaps elsewhere in eastern Europe. These eagles still rarely occur as breeders in southwest Russia from Stavropol to Astrakhan. The steppe eagle is still mapped to breed down to Makhachkala and Maykop to as far west as Leningradskaya, up north as far as the lower Volga and down to the Caspian Sea nearly as far as Makhachkala and south of Fort-Shevchenko. The breeding range extends through appropriate habitat in much of Kazakhstan, from north of Nur-Sultan south to (albeit spottily) to Kyzylorda as well as around the former Aral Sea. From their main breeding areas to the north, steppe eagles breed also marginally in northeastern Kyrgyzstan and perhaps northern Uzbekistan. The breeding distribution is essentially continuous as sweep far to the east in Russia as Transbaikal and Altai. The steppe eagle also breeds in large stretches of western and northern China such as Tian Shan, Xinjiang, the Gobi area, Gansu, Ningxia, northern Tibet (by far their southernmost breeding area), Inner Mongolia and reach their eastern breeding limits in Manchuria and elsewhere in northeastern China. The species breeding range is also quite broad into Mongolia excluding the northern portion. <p>The steppe eagle is entirely migratory, wintering in east and, to a lesser extent, southern Africa. Their African range can extend western to southern Sudan, almost throughout east Africa, to the easternmost part of Democratic Republic of the Congo. The southern African wintering range extends to central Angola, northern and eastern Namibia south to Botswana, Zambia, Zimbabwe, Eswatini and northern South Africa, including former Transvaal and northern Natal as well as rarely south of the Orange River In South Africa, steppe eagles are reportedly often frequent only in the lowveld of Kruger National Park area. The steppe eagle's wintering range also extends into the Middle East. They occur broadly in the season in several central and southern parts of the Arabian Peninsula as well as regularly in eastern Iraq and western Iran with odd ones north to Turkey and Georgia. Although sometimes recorded as occurring "somewhat" in Arabia, more extensive surveying has revealed that many, if not more, steppe eagles wind up winter in the peninsula rather than Africa, and that the largest ever winter numbers were recorded in Saudi Arabia, where around 7200 individuals (or perhaps up to 9% of the current world population) were recorded near Riyadh. As many as 3000 have also been similarly recorded in the nation of Oman. Other nations to host wintering steppe eagles include Yemen, Azerbaijan and Syria as well as, albeit rarely doing so, in the United Arab Emirates, Lebanon and Kuwait.<p>Unusually, a few overwintering steppe eagles have been now recorded in Kazakhstan, apparently near Shymkent, in the Aksu-Zhabagly Nature Reserve, the valley of the Syr Darya, the Shardara Dam and towns of the East Kazakhstan Region. In south Asia, the species in winter may occur from Afghanistan (rarely wintering still in the Nuristan Province) and in much of the Indian subcontinent. Pakistan's Poonch and Jhelum valleys of Azad Kashmir are known to host a mean of 154 steppe eagles per study area. In India, they may occur mainly south to Madhya Pradesh, the Indo-Gangetic Plain, the Deccan Peninsula and Himalayan zone, Mizoram, Assam and southern Orissa. Vagrants have been recorded in India to Periyar National Park, Mahendragiri, Kanyakumari Wildlife Sanctuary and Mudumalai National Park. The wintering range extends east to Tibet (although the species is said to be gone from Lhasa in recent years), Nepal, Burma and broadly in east China from southeastern Guizhou to Hainan and southwestern Guangdong. Recent wintering records reflect the species as lingering seasonally at different points of the non-breeding season, albeit very seldom, in central and southern Myanmar, western Thailand, peninsular Malaysia and northern Vietnam. The species may have been aided in expanding their eastward wintering range by deforestation practice. <p>The steppe eagle appears broadly in many nations between their central Eurasian breeding areas and their generally tropical Indo and African wintering grounds. As a matter of fact, the largest concentrations of the species tend to occur at times of passage. The steppe eagle can also vagrate not infrequently far away from traditional migration sites, and has turned up in many areas from western Europe to as far east as Japan. Vagrant steppe eagles have been recorded in at least the following nations or regions: at least 6 nations in west Africa Morocco, Tunisia, the Netherlands, Finland (at least 50 times) as well as Spain and France, the Czech Republic, Bulgaria and Romania (in both of which they once bred but were extirpated), Greece Mordovia, Yakutia, the Korean Peninsula and probably down to Borneo in Asia. Migration sites include both mountainous ridges and the larger seas along their routes. Steppe eagles predominantly use two main migration routes: one radiates across the Middle East and Arabia, with many birds stopping to winter, but many too migrate around the Red Sea to winter in Africa while the other main migration path frequently involves farther eastern breeding eagles moving along many ridges and prominent flyways before radiated across a broad path through the Himalayas, in order to reach the south Asian and other Asian wintering sites. Less known or less frequently migration paths before these well-known routes of passage may lead steppe eagles around the Black Sea in the west and, much more frequently, around the Caspian Sea farther east. Nations known to be visited by steppe eagles almost exclusively in migratory passage include Egypt, most but not all of Syria, Turkmenistan and Afghanistan and much of east China from Tuquan County to about Xiamen. Points of migration bottleneck, where large numbers of steppe eagles are frequently recorded, are known in areas including Israel, especially around Eilat, Suez (in Egypt), Bab-el-Mandeb (in Yemen), some parts of the nation of Georgia and, in the Himalayan region, especially within Nepal but also sometimes en masse in Pakistan and northern India. Migration sites of minor significance are less known but include Alborz. The steppe eagle tends to breed in open dry country, within the characteristic habitat it is named after: the steppe both in both upland and lowland areas. In Kazakhstan, it is known to generally occur in drier parts of the steppe than some other raptors like harriers. This species generally avoids utilizing agricultural land such as arables and most other human-fragmented areas, however, they can be somewhat tolerant of nesting near roads. Associated habitats are frequented when breeding such as flat plains, arid grassland, semi-desert and even desert edge. Most members of the species breed at lower levels but largely in eastern part of the range also will nest in poorly vegetated dry rocky hillsides such as granite massifs and upland valleys, though generally avoid truly mountainous areas. <p>Wintering steppe eagles often occur much more frequently in human-modified areas in order to access easy foods. These include landfills and livestock carcass dumps, these being used frequently everywhere from Arabia to India. More natural habitats used most often by wintering steppe eagles tend to be various wetlands or other waterways where they are available. In winter, mostly savanna and grasslands are the predominant habitat used in Africa, also sometimes dry woodland. Study in Botswana indicated that wintering steppe eagles there appeared to be indifferent to land use changes by humans. In Zambia and Malawi, it was found that the steppe eagle was only frequent in high-elevation plateau areas from 370 to 2,400 m (1,210 to 7,870 ft) metres above sea level. Use of plateaus was also frequent in Zimbabwe, often where open savanna woods of Acacia stand as well as the use of cultivated areas such as wheat stubble fields by eagles. Iraqi wintering steppe eagles often used dump sites as well as deserts and semi-arid areas, with more steppe, other grassland and mountain slopes used in northern Iraq in winter. In Armenia steppe eagles are apparently frequent in old fields and orchards. In south Asia they usually use open country and often frequents large lakes and other wetlands near arid areas but may accept, or even prefer, more heavily wooded areas (however the first records from peninsular Malaysia seem to be from open areas created by deforestation). Although usually a breeder of lowlands, it has been known to live at elevations of up to 2,300 m (7,500 ft) and locally to 3,000 m (9,800 ft) in mountains, on passage can occur to over 4,500 m (14,800 ft) sometimes even to 7,925 m (26,001 ft), as was recorded on Mount Everest. Compared to other Palearctic migrating eagles, the steppe eagle seems to perhaps be slightly more tolerant of a wider range of climatic conditions, including rather humid conditions in India provided subsistence is available as well as up to 50 cm (20 in) of snow cover in Kazakhstan (living off of urban pests).

Brutgebiet

PAL : c

Überwinterungsgebiet

OR, Arabian Pen. and AF

Zugverhalten

Complete migrants

Verhalten

The steppe eagle is sometimes regarded as solitary but is frequently seen in the company of conspecifics throughout the year. Besides the obvious breeding pair, they often flock during migration and aggregate in occasionally ample numbers during non-breeding times, usually at fruitful feeding sites, sometimes briefly cooperating with one another especially to klepoparasitize other birds of prey. Steppe eagles fly with slow, deep and stiff-looking wing beats, holding wings fully extend on upstrokes, rendering a heavier flight pattern than spotted eagles. The flight of the steppe eagle is well-analyzed such as experiments with a captive male and observations of migrants in Israel. It appears that the underwing coverts operate as a high-lift device and probably provide stability through unsteady maneuvers, otherwise positive loading on the wings can be maintained. Whilst soaring, generally the wings are held flattish or slightly flexed but sometimes with the hands lowered. About 90% of flight by these eagles in Israel was gliding or soaring. They often fly with the head dropped with hands arched in a glide or often arms straight out and hands drooped. The drooping wing flight method, peculiar to the steppe eagle as well as to the greater spotted eagle, is sometimes also called the "tuck", and is thought to be a gust response precipitated by a transient drop in aerodynamic loading. Steppes adapt their flight to wind and thermal conditions as was studied in Israel, increasing their gliding airspeed under strong thermal convections or opposing winds. This study determined that a combination of circling in thermals and inter-thermal gliding was interspersed with soaring in straight-line glide. Israeli migrants flew up to 1,600 m (5,200 ft) above the ground but 90% were under 1,000 m (3,300 ft) and half were below 400 m (1,300 ft). The Israeli steppe eagles were able to maintain a mean climbing rate of 1.9 m (6.2 ft) per second, a mean cross-country air speed of 12.4 m (41 ft) per second and a mean of 15.6 m (51 ft) per second in glides; the flight was similar as in other common raptors here but the steppe eagle attained the highest mean cross-country speeds. Steppe eagles tend not to be very vocal especially when not breeding. Their main call is a raspy bark which is similar to that a tawny eagle, despite being mildly deeper. In aerial displays, a loud whistle has been recorded, quite unlike any vocalization of a tawny eagle. Other call recorded have included mainly low and croaking notes aside from a high shriek when startled.<p>Steppe eagles appeared to have evolved the strategy of migrating from their breeding grounds, due in large part to the temporary seasonal availability of their main prey, ground squirrels. They probably migrate in greater numbers than any other eagle in the world and can appear to be frequent enough at migration sites that they may mask less numerous migrating eagles that are mistakenly missed in their ranks. The migratory behaviour of this species is arguably amongst the best-studied aspect of its entire biology. Autumn migration often begins around October on fairly broad fronts, and may peak around late October. It usually ends in late November to December but steppe eagles frequently travel somewhat nomadically while not breeding and so individuals may not reach their winter terminus point until about January. Spring migration usually commences in February, peaking early from late February to March, with likely all gone from Africa by the end of the latter month, then continuing in a diminishing trickle into April and May. In passage at Suez, the steppe eagle is one of the earlier migrating raptors on average alongside the long-legged buzzard (Buteo rufinus), averaging about a month sooner in passage than the common buzzard (Buteo buteo) (the most common migrant there) and slightly sooner than the lesser spotted eagle, as well as much sooner than some other raptors there. On average, the wintering period in Africa is relatively brief, at a mean of about up to about 4 months (down to about 2), while adult steppe eagles spend up to 7 months (max of around 5 months for a young eagle) on their breeding grounds. In autumn records from Africa, younger eagles migrate the earliest and adults the latest. Radio-tagging studies confirmed, much as in the lesser spotted eagle, that in spring juveniles migrated later, wandering about more so and came back to the summering grounds much later. One young steppe eagle that was banded in passage in the United Arab Emirates wintered initially in Yemen before returning for the summer to Kazakhstan, then migrating to eastern Africa the following winter, showing that they can change their migratory habits over time. Many studies corroborate that steppe eagles generally migrate lesser distances as they age.<p>Peak movements around the Red Sea show as many as 76,000 steppe eagles moving over Bab-el-Mandeb in the fall of 1987, with up to 65,000 (in 1981) in Suez and up to 75,000 in Eilat, Israel in the year 1985. Once migrating steppe eagles enter Africa in autumn, no mass migrations have been recorded anywhere for the species in the continent. Although not large, some semi-significant spring movements were detected in Egypt, despite none being recorded in the fall. In autumn, steppe eagles usually pass over Bab-el-Mandeb in the north of Red Sea while in spring they predominantly cross to the south of the Red Sea around Suez. The mean number of steppe eagles that annually pass over Eilat in spring are estimated at 28,032 with a mean peak day of 10 March, making them roughly the fourth most common migrating raptor in spring there (and they often pass in intermingled flocks with other soaring raptors, but not those with powered flight). In Eilat, steppe eagles constitute 6.4% of all raptors seen, nearly all of the Aquila eagles seen and, among those that could be aged, an estimated 60–70% of the steppes seen were thought to be adults. More unusually, the steppe eagle may be the only raptor to also use Israel as a common migratory flight path in autumn as well as spring, with even commoner migrating raptors such as common buzzards and European honey buzzards (Pernis apivorus) being rare there in the fall. In Nepal over 2.5 weeks starting on 20 October, nearly 7852 steppe eagles were tallied, making up more than 80% of the recorded migrating raptors, with peak times of movement being between 10:00 AM and 4:00 PM, especially between noon and 2:00 PM. Over 3 years of study in Nepal, 21,447 steppe eagles were recorded (as many as 1102 within a day and a mean of about 15.2 an hour) at the counting sites. Strong evidence of east-to-west migratory movements, rather than south or northbound, has been made in the Kathmandu Valley. It was indicated based on the directional studies that especially juveniles from the eastern part of the breeding may be more frequently migrate westbound to reach wintering areas such as the Middle East and Africa. On the contrary, juveniles and subadults during the wintering season seem to considerably outnumber adults in the Indian subcontinent so many do head due south. Of 3381 ageable steppe eagles in passage in Nepal, 56% were juveniles or immature, 44% were adults; of 7852 eagles, 58% migrated in groups of 1–5, 30% in 5–20 groups and 12% in larger flocks. In Himachal Pradesh of India, about 11,000 steppe eagles were recorded in autumn migration in 2001 and about 40% less were counted the next spring. This study indicated different migratory paths being used in the seasons, presumably following the winds predominant direction around the terrain, with the westerly autumn migration mostly in the western Himalayas and the easterly spring migration more so in the east of Nepal. Staging areas are not well-delineated in India but appear to concentrate around feeding sites such as landfills. A single female that was radio-tagged in Mongolia was recorded to travel southwest and stop in southeastern Tibet, which is also the southernmost part of the species breeding range. The data from this female indicated that not all steppe eagles move to warmer climates and, based on that she remained stationary until her return to Mongolia, that she was not nomadic as many eagles of the species are. During return spring migration, the steppe eagles in passage in Nepal will reportedly amass into groups of approximately 5 to 20 eagles at only about 20 to 70 m (66 to 230 ft) above the terrain before rising up to cross between the snow-covered peaks. <p>16 radio-tagged eagles that returned in their first spring migration to their Kazakh summering grounds were recorded to winter as first-year juveniles either, in roughly equal measure, in the Arabian Peninsula or southern Africa, and covered straight-line distances, ranging from 3,489 to 9,738 km (2,168 to 6,051 mi), although individually could meander up to 20,644 km (12,828 mi) for one eagle migrating from wintering grounds Botswana. Of the 16 returning Kazakhstan eagles, spring migration lasted an average of 40 days, ranging individually from 38 to 54 days and covered a mean of 355 km (221 mi) each day. The migration path generally led the eagles around almost every direction of the Red Sea, many also passing over Israel and some wrapping around the Caspian Sea. A different radio-tagging study of 19 juveniles (about 57% of which survived) from Russian or Kazakh sites found that autumn movements in the 1st year migration averaged 4,222 km (2,623 mi) and confirmed not only that they freely changed wintering sites anywhere from India to southern Africa but they never returned, surviving or not, to their natal site in the 1st year, instead return to wandering widely across the northern steppe. The 1st migration averaged 52 days and were much briefer for females than for males, with the discrepancies more pronounced for eagles originating from the Altai Mountains. 15 birds tracked in this study were found to have migrated most frequently to winter in south Pakistan (right along the borderlands to India) or in eastern Turkmenistan. Spring migration began on a mean date of 25 March for the 15 young eagles and lasted about 26 days on average, covering a mean of 3,925 km (2,439 mi), with females initiating migration on average 18 days later than males and migrating more briefly, more quickly and more often with fewer stops than males. 9 eagles which were tracked successfully in their first spring passage in this study wandering widely mostly in natural steppe hunting for squirrels and 8 of these tracked to their 2nd autumn migration took about 1.5 times shorter on their 2nd autumn passage and migrated about 17% less far on average.

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