The long-legged buzzard (Buteo rufinus) is a bird of prey found widely in several parts of Eurasia and in North Africa. This species ranges from Southeastern Europe down to East Africa to the northern part of the Indian subcontinent. The long-legged buzzard is a member of the genus Buteo, being one of the larger species therein. This species is simultaneously considered relatively powerful and aggressive for its taxonomic group as well as a relatively sluggish raptor overall. Like most buzzards, it prefers small mammals such as rodents, including gerbils, ground squirrels, voles and rats, also taking reptiles, birds and insects as well as carrion. Adaptable to a variety of habitats, long-legged buzzards may nest on a variety of surfaces, including rocks, cliffs and trees. It is a typical buzzard in its reproductive biology. The long-legged buzzard is widely distributed and appears to be quite stable in population. Therefore, it is considered as Least Concern by the IUCN.

This is a large and fairly sturdy Buteo. The long-legged buzzard possesses a relatively large bill on a smallish head, long wings and a rather long tail and relatively long legs with powerful feet. The species tends to be considered sluggish, perching openly and prominently and in rather upright positions on a rock, crag or similar vantage point with a good commanding view; they will also perch regularly on artificial raised points such as pylons or utility poles. The long-legged buzzard also often takes to standing on the ground where it walks slowly, often waddling somewhat. This species is highly variable in plumage, with three to four main morphs. The adult pale morph long-legged buzzard has a rather plain pale head, coloured creamy rufous to light sandy with at most a few darker streaks on the crown and a dark line through an eye, usually with a more solidly dark nape. The pale morph possess dark brown upper parts with sandy buff streaks against a more conspicuous sandy-brown mantle and wing coverts with dark feather-eters causing a contrasting effect. The pale morph adult's tail is light rufous-orange. The paleness of the head in light morphs continues down to breast, the lower part of which having pencil thin streaks, while the belly down to flanks and trousers is a darker rufous-brown. Meanwhile, the intermediate adult are similar to pale adult but with somewhat richer colour, darker and more rufous upperparts and having a slightly darker and more patterned breast. The rufous morph, arguably separate from the intermediate, is more ochracecous overall and a darker rufous on the dark parts of the plumage against the more contrasting pale head. Some rufous adult long-legged buzzards can show a greyish tail with some banding and at times a darker subterminal band. Dark morph adults are all blackish-brown to black with some whitish streaks on nape. The tail of dark morphs are grey to brown-grey with a broad subterminal band and 7 rather narrow and faint bars although many completely lack the latter bars. Juveniles of the pale, intermediate and rufous morphs are similar to the respective adults of their morphs but tend to possess neater, paler edging above, especially on the tips of the greater and median coverts. Also the juveniles are more streaky about the head and breast with tail going from pale whitish darkening outwards to grey-brown with irregular faint brown bars. Dark morph juveniles are less dark than the adult of that morph, sometimes evidencing a small paler patch on breast. The juvenile dark morph long-legged buzzard's tail pattern differs from the dark adult, generally browner than adult with 3 very broad bands and a slightly broader subterminal band but dark morph juvenile tails apparently very variable. Juvenile plumage lasts up to 2–3 years when first breeding occurs. Adults have very dark brown eyes, while the eyes of juveniles are pale grey to greyish yellow turning light brown before darking. The cere and legs are both dull yellow.

In flight, the long-legged buzzards appears as a mid-sized rather broad-bodied raptor. Possessing an almost eagle-like silhouette, it tends to appear with a protruding head with a somewhat heavy bill, long broad wings with fairly straight edges and only slightly tapering hands with rounded five-fingered end. It is relatively long-tailed with the tail having a fairly rounded shape. Juveniles tend to be slimmer looking with narrower wings and more S-shaped trailing edges as well as a somewhat longer tail. Long-legged buzzards tend to fly with comparatively slow, deep beats and to have a relatively slow flight. The species glides with their arms raised and hands more level, wings noticeably kinked at carpals and soars in wide circles with the wings in shallow dihedral. The upward bent tips can enhance their eagle-like appearance. Long-legged buzzards often hover frequently and for extended periods. In the flight, the whitish based orangey tail often looks all white at a distance and to stand out in its paleness against the dark rear body and the rear wings. The primary coverts and many greater coverts are blackish in adult long-legged buzzards with the greater coverts pale tipped. Adults are dark grey on the flight feathers with blackish bars radiating outwards on wingtips and on the trailing edges. The underwing coverts are usually lightly streaked with rufous in pale adults, while intermediate adult has a stronger contrast from pale head and breast to darker, browner upperbody and wing coverts, breast and wing linings. The flying rufous adult tends to look more uniform above with colours varying from ochre to tawny to darker rufous brown and to possess richer coloured darker parts, with the tail very variable in rufous morph. Dark adult in flight may appear with or without a pale nape patch. Dark morph long-legged buzzards above evidence pale bases to primaries, some less dark individuals showing slight contrast of brown-tinged wing coverts against blacker carpal areas with greyish cast to secondaries but tail more obviously pale and greyer and variable. Below dark morph adult striking contrasting from dark body and underwing coverts against pale flight feathers. Juvenile long-legged buzzards are evidently more streaky in pale, intermediate and rufous morphs with differing wing shape. Juveniles of the 3 morphs have comparatively uniform secondaries above with a paler based hand, the inner four primaries being thinly barred, the whitish tail becoming greyer brown and appear indistinctly barred distally. The trailing wing edges are more diffuse, greyer and narrower than on adults with a dark line often evidence along greater coverts. Dark morph juveniles in flight even more uniform above without darker trailing edges above and below greyish secondaries are much duskier-looking with broader but diffuse barring and often markedly wide trailing edges, this increasing the contrast against the dark tipped whitish hand.

This is one of the largest species of the genus Buteo. Only two species, the upland buzzard (Buteo hemilasius) and the ferruginous hawk (Buteo regalis), notably exceed the average and maximum weight of nominate long-legged buzzards or attain similar wingspans, but several other species of the genus broadly overlap in body size with the long-legged buzzard (for instance the Galapagos, rufous-tailed and red-tailed hawks and the Augur, rough-legged and jackal buzzards). Length can range from 50 to 66 cm (20 to 26 in) and wingspan from 112 to 163 cm (3 ft 8 in to 5 ft 4 in). Mean wingspan may be about 145 cm (4 ft 9 in), with wingspans surely rivaling the upland buzzard as the greatest of all Buteo. The long-legged buzzard displays the typical size sexual dimorphism in favour of females, as they may be to 15% larger and can average up to 30% heavier. The mean body weight of males is 1,035 g (2.282 lb), amongst a sample of 8 with weights ranging from 590 to 1,281 g (1.301 to 2.824 lb), while the mean was 1,315 g (2.899 lb) in females, in a sample of 11 ranging from 945 to 1,760 g (2.083 to 3.880 lb). Meanwhile, the weights of migrating long-legged buzzards migrating in Eilat were 1,182 g (2.606 lb) in mature buzzards and 1,047 g (2.308 lb) in second-year juveniles. The measurements of live Indian long-legged buzzards were 1,000 to 1,300 g (2.2 to 2.9 lb) with slighter lengths of 46 to 55 cm (18 to 22 in) and wingspans of 129 to 150 cm (4 ft 3 in to 4 ft 11 in). Among standard measurements, nominate subspecies males attain a wing chord of 405 to 459 mm (15.9 to 18.1 in) while the female attains a wing chord of 428 to 496 mm (16.9 to 19.5 in). In males the tail may measure 204 to 244 mm (8.0 to 9.6 in) while the female may measure 223 to 262 mm (8.8 to 10.3 in). In tarsal length, males may measure 83 to 93 mm (3.3 to 3.7 in) while females attain 87 to 96 mm (3.4 to 3.8 in). In the nominate race, the culmen from the cere is 23.4 to 30 mm (0.92 to 1.18 in) in both sexes, with an average of 27.9 mm (1.10 in) in migrants at Eilat. Mature migrants in Eilat measured from 24.8 to 32.1 mm (0.98 to 1.26 in), averaging 27.8 mm (1.09 in), on the enlarged hallux-claw.

Paler individuals of the long-legged buzzard are typically reasonably distinctive but their highly variable plumage leads to mistaken identity. The main confusion is with the even more variable common buzzard (Buteo buteo), principally of the steppe subspecies, which breeds and migrates in often similar areas. Steppe buzzards are told apart by various features of plumage, i.e. darker head and chest with a contrasting paler breast band, fully barred and darker uppertails, less distinct carpal patch both above and below, more contrasting wing lining with median coverts paler, with the greater covert darkest. Due to much variation in plumage, steppe buzzards often not reliably distinguished and in distant sightings best told apart by their smaller size and differing proportions. The steppe buzzard is distinctly smaller, of more compact build and possess a distinctly shorter wings and tail than nominate long-legged buzzards. Furthermore, the steppe buzzard has a more pronounced head but less protruding bill and flies with faster but stiffer and less flexible beats. Furthermore, steppe buzzards tend to fly with flatter wings in a glide and less pronounced dihederal without tips pointed up. Dark morphs of the respective species are so similar that they must be told by size, proportions and flight actions. Especially hard to tell apart from the steppe buzzard is the smaller North African subspecies. In Asia the long-legged buzzard is similar to the upland buzzard, which averages slightly bigger in size but is somewhat narrower winged. Typically the upland species has a large white patch on the hand above, with a uniform looking greyish white tail (with at most 2-3 dark bars only visible at close range), darker, more earthen brown on the breast and thighs and lacks the long-legged's typical warm, rufous tones. In dark morph upland buzzards, though they may manifest some darker ground colour on under secondaries and sometimes show pale U on breast but otherwise almost identical in appearance to dark morph long-legged buzzards. The only other Buteo that can be potentially confused with the long-legged buzzard is the migrant rough-legged buzzard (Buteo lagopus) which is similar in size, proportions and flight behaviour, extending to hovering (however the rough-legged is marginally smaller in size with shorter legs and a shorter bill). The rough-legged buzzard should be told apart from the long-legged by having a distinctive white based tail with a broad dark subterminal band as well as fully feathered legs, Juvenile rough-legged buzzards lack the dark underwing diagonals of many juvenile long-legged buzzards. The long-legged buzzard is potentially confusable with other medium or large unrelated species of raptor from outside of the Buteo, including multiple species of small to mid-sized eagle and two species of honey buzzard. However, all of these usually tend to have a number of distinctive morphological, especially the proportion and shapes of their wings, head and tail and flight actions, as well as plumage features that tend to easily separate them from even the most similarly hued and sized of long-legged buzzards.

The long-legged buzzard's voice is not well studied nor is it believed to be particularly vocal. The species is known to sometimes calls on display but it is less vocal than common buzzard. The call is similar to the latter species but the notes are shorter and slightly higher. The long-legged buzzard's commonest call is a short mew. It is also sometimes transcribed as a kyaaah and drops in pitch at the end of the brief 0.5-0.8 second call. It is said that compared to the common buzzard, the calls of the long-legged buzzard are "less squealing" and more "gull-like". A long-legged buzzard leaving its nest in Morocco just after sunrise was said to have uttered a repeated ar note, shorter fuller and apparently lower than the comparable call of a common buzzard.

The long-legged buzzard inhabits arid areas of northern Africa, southeastern Europe, west and central Asia east to China, and down to as far as central India. The farthermost western part of their breeding range is in west Africa, in Western Sahara, extreme northern Mauritania, much of Morocco west to northern Algeria (spottily elsewhere in the nation), Tunisia and northern Libya (mainly northwestern parts). Long-legged buzzards occur accidentally in several other parts of Africa. In mainland Europe, they mainly nest in the southeastern region. Nesting long-legged buzzards have been known in eastern Hungary, central and eastern Ukraine, southern Moldova, southern and far eastern Romania, southern Serbia and more broadly in Bulgaria and somewhat so in northern Greece. Recent sightings indicate that there is a small population in the Apulian region of south-eastern Italy. Similarly, increasing records of long-legged buzzards are known in far southern Spain with the first nesting occurring in Gibraltar in 2009. The recent colonisation Europe due to the climate in southern Europe becoming more suitable for this species. Vagrant long-legged buzzards have been documented in many parts of Europe, including Finland, Denmark, the Netherlands, France, Poland, Czech Republic, Slovakia, and one record in Shetland in Great Britain on 1 September 2019. Out of Europe in the eastern Mediterranean or Asia Minor, the long-legged buzzard is one of the most continuously found and abundant breeding resident raptors, being distributed throughout all of Turkey, Cyprus, Armenia, Georgia and Azerbaijan. The range continues into southwestern Russia up to about Saratov and Orenburg.

It is also widely and regularly distributed through much of the Middle East, residing almost throughout Syria, Lebanon, Israel, as well as the northern central parts of both Iraq and Iran. More uncommonly the breeding ranges extends into Oman, the United Arab Emirates, Yemen and Saudi Arabia. The range continues almost throughout Central Asia, residing in essentially all of Turkmenistan (including broadly along the Caspian Sea coast), Uzbekistan, all but the northern stretches of Kazakhstan, Tajikistan, Kyrgyzstan and northern and central Afghanistan. The breeding range discontinues in Northwestern China but isolated breeding was documented in the Kashmir region, perhaps straddling both Pakistan and India. During times of passage, long-legged buzzards have been seen more broadly in areas such as the Arabian Peninsula, southern Iraq, western China and northeast Africa, with those that breed in Europe, Russia and Central Asia often departing their breeding grounds for the winter. The wintering areas of migrating long-legged buzzards extend through much of lower Central Asia and the Indian subcontinent including southern Afghanistan, much of Pakistan and northern India through to Nepal, Bhutan and Bangladesh. Vagrants have been recorded to as south as Sri Lanka, northern Burma and the Andaman Islands. Less consistent wintering populations may live from central Sudan and Eritrea, northern South Sudan, much of Ethiopia, into far northeastern Uganda and central Kenya, seldom into far northern Tanzania.