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Facts & Profile
Common buzzard Buteo buteo

The common buzzard (Buteo buteo) is a medium-to-large bird of prey which has a large range. A member of the genus Buteo, it is a member of the family Accipitridae. The species lives in most of Europe and extends its breeding range across the Palearctic as far as the Russian Far East , northwestern China (Tien Shan) and northwestern Mongolia Over much of its range, it is a year-round resident. However, buzzards from the colder parts of the Northern Hemisphere as well as those that breed in the eastern part of their range typically migrate south for the northern winter, many culminating their journey as far as South Africa. The common buzzard is an opportunistic predator that can take a wide variety of prey, but it feeds mostly on small mammals, especially rodents such as voles. It typically hunts from a perch. Like most accipitrid birds of prey, it builds a nest, typically in trees in this species, and is a devoted parent to a relatively small brood of young. The common buzzard appears to be the most common diurnal raptor in Europe, as estimates of its total global population run well into the millions.

Description & appearance

The common buzzard is a medium-sized raptor that is highly variable in plumage. Most buzzards are distinctly round headed with a somewhat slender bill, relatively long wings that either reach or fall slightly short of the tail tip when perched, a fairly short tail, and somewhat short and mainly bare tarsi. They can appear fairly compact in overall appearance but may also appear large relative to other commoner raptorial birds such as kestrels and sparrowhawks. The common buzzard measures between 40 and 58 cm (16 and 23 in) in length with a 109–140 cm (43–55 in) wingspan. Females average about 2–7% larger than males linearly and weigh about 15% more. Body mass can show considerable variation. Buzzards from Great Britain alone can vary from 427 to 1,183 g (0.941 to 2.608 lb) in males, while females there can range from 486 to 1,370 g (1.071 to 3.020 lb).
In Europe, most typical buzzards are dark brown above and on the upperside of the head and mantle, but can become paler and warmer brown with worn plumage. The flight feathers on perched European buzzards are always brown in the nominate subspecies (B. b. buteo). Usually the tail will usually be narrowly barred grey-brown and dark brown with a pale tip and a broad dark subterminal band but the tail in palest birds can show a varying amount a white and reduced subterminal band or even appear almost all white. In European buzzards, the underside coloring can be variable but most typically show a brown-streaked white throat with a somewhat darker chest. A pale U across breast is often present; followed by a pale line running down the belly which separates the dark areas on breast-side and flanks. These pale areas tend to have highly variable markings that tend to form irregular bars. Juvenile buzzards are quite similar to adult in the nominate race, being best told apart by having a paler eye, a narrower subterminal band on the tail and underside markings that appear as streaks rather than bars. Furthermore, juveniles may show variable creamy to rufous fringes to upperwing coverts but these also may not be present. Seen from below in flight, buzzards in Europe typically have a dark trailing edge to the wings.

If seen from above, one of the best marks is their broad dark subterminal tail band. Flight feathers of typical European buzzards are largely greyish, the aforementioned dark wing linings at front with contrasting paler band along the median coverts. In flight, paler individuals tend to show dark carpal patches that can appears as blackish arches or commas but these may be indistinct in darker individuals or can appear light brownish or faded in paler individuals. Juvenile nominate buzzards are best told apart from adults in flight by the lack of a distinct subterminal band (instead showing fairly even barring throughout) and below by having less sharp and brownish rather than blackish trailing wing edge. Juvenile buzzards show streaking paler parts of under wing and body showing rather than barring as do adults. Beyond the typical mid-range brownish buzzard, birds in Europe can range from almost uniform black-brown above to mainly white. Extreme dark individuals may range from chocolate brown to blackish with almost no pale showing but a variable, faded U on the breast and with or without faint lighter brown throat streaks. Extreme pale birds are largely whitish with variable widely spaced streaks or arrowheads of light brown about the mid-chest and flanks and may or may not show dark feather-centres on the head, wing-coverts and sometimes all but part of mantle. Individuals can show nearly endless variation of colours and hues in between these extremes and the common buzzard is counted among the most variably plumage diurnal raptors for this reason. One study showed that this variation may actually be the result of diminished single-locus genetic diversity.

Voice, singing & call

Resident populations of common buzzards tend to vocalize all year around, whereas migrants tend to vocalize only during the breeding season. Both nominate buzzards and steppe buzzards (and their numerous related subspecies within their types) tend to have similar voices. The main call of the species is a plaintive, far-carrying pee-yow or peee-oo, used as both contact call and more excitedly in aerial displays. Their call is sharper, more ringing when used in aggression, tends to be more drawn-out and wavering when chasing intruders, sharper, more yelping when as warning when approaching the nest or shorter and more explosive when called in alarm. Other variations of their vocal performances include a cat-like mew, uttered repeatedly on the wing or when perched, especially in display; a repeated mah has been recorded as uttered by pairs answering each other, further chuckles and croaks have also been recorded at nests. Juveniles can usually be distinguished by the discordant nature of their calls compared to those of adults.

Habitat

The common buzzard generally inhabits the interface of woodlands and open grounds; most typically the species lives in forest edge, small woods or shelterbelts with adjacent grassland, arables or other farmland. It acquits to open moorland as long as there is some trees. The woods they inhabit may be coniferous, temperate broad-leafed or mixed forests with occasional preferences for the local dominant tree. It is absent from treeless tundra and sporadic or rare in treeless steppe but can migrate through these, and may be found to some extent in both in mountainous or flat country. Buzzards in well-wooded areas of eastern Poland largely used large, mature stands of trees that were more humid, richer and denser than prevalent in surrounding area, but showed preference for those within 30 to 90 m (98 to 295 ft) of openings. Mostly resident buzzards live in lowlands and foothills, but they can live in timbered ridges and uplands as well as rocky coasts, sometimes nesting on cliff ledges rather than trees.

Buzzards may live from sea level to elevations of 2,000 m (6,600 ft), breeding mostly below 1,000 m (3,300 ft) but they can winter to an elevation of 2,500 m (8,200 ft) and migrates easily to 4,500 m (14,800 ft).[2] In the mountainous Italian Apennines, buzzard nests were at a mean elevation of 1,399 m (4,590 ft) and were, relative to the surrounding area, further from human developed areas (i.e. roads) and nearer to valley bottoms in rugged, irregularly topographed places, especially ones that faced northeast. Common buzzards are fairly adaptable to agricultural lands but will show can show regional declines in apparent response to agriculture. Changes to more extensive agricultural practices were shown to reduce buzzard populations in western France where reduction of “hedgerows, woodlots and grasslands areas" caused a decline of buzzards and in Hampshire, England where more extensive grazing by free-range cattle and horses led to declines of buzzards, probably largely due to the seeming reduction of small mammal populations there. Similarly, urbanization seems to negatively affect buzzards, this species being generally less adaptable to urban areas than their New World counterparts, the red-tailed hawk. Although peri-urban areas can actually increase potential prey populations in a location, individual buzzard mortality, nest disturbances and nest habitat degradation rises significantly in such areas.

Hunting & food

The common buzzard is a generalist predator which hunts a wide variety of prey given the opportunity. Their prey spectrum extents to a wide variety of vertebrates including mammals, birds (from any age from eggs to adult birds), reptiles, amphibians and, rarely, fish, as well as to various invertebrates, mostly insects. Young animals are often attacked, largely the nidifugous young of various vertebrates. In total well over 300 prey species are known to be taken by common buzzards. Furthermore, prey size can vary from tiny beetles, caterpillars and ants to large adult grouse and rabbits up to nearly twice their body mass. Mean body mass of vertebrate prey was estimated at 179.6 g (6.34 oz) in Belarus. At times, they will also subsist partially on carrion, usually of dead mammals or fish. However, dietary studies have shown that they mostly prey upon small mammals, largely small rodents. Like many temperate zone raptorial birds of varied lineages, voles are an essential part of the common buzzard's diet.

This bird's preference for the interface between woods and open areas frequently puts them in ideal vole habitat. Hunting in relatively open areas has been found to increase hunting success whereas more complete shrub cover lowered success. A majority of prey is taken by dropping from perch, and is normally taken on ground. Alternately, prey may be hunted in a low flight. This species tends not to hunt in a spectacular stoop but generally drops gently then gradually accelerate at bottom with wings held above the back. Sometimes, the buzzard also forages by random glides or soars over open country, wood edges or clearings. Perch hunting may be done preferentially but buzzards fairly regularly also hunt from a ground position when the habitat demands it. Outside the breeding season, as many 15–30 buzzards have been recorded foraging on ground in a single large field, especially juveniles. Normally the rarest foraging type is hovering. A study from Great Britain indicated that hovering does not seem to increase hunting success.

Breeding & mating

Common buzzards maintain their territories through flight displays. In Europe, territorial behaviour generally starts in February. However, displays are not uncommon throughout year in resident pairs, especially by males, and can elicit similar displays by neighbors. In them, common buzzards generally engage in high circling, spiraling upward on slightly raised wings. Mutual high circling by pairs sometimes go on at length, especially during the period prior to or during breeding season. In mutual displays, a pair may follow each other at 10–50 m (33–164 ft) in level flight. During the mutual displays, the male may engage in exaggerated deep flapping or zig-zag tumbling, apparently in response to the female being too distant. Two or three pairs may circle together at times and as many as 14 individual adults have been recorded over established display sites. Sky-dancing by common buzzards have been recorded in spring and autumn, typically by male but sometimes by female, nearly always with much calling. Their sky-dances are of the rollercoaster type, with upward sweep until they start to stall, but sometimes embellished with loops or rolls at the top.

Next in the sky-dance, they dive on more or less closed wings before spreading them and shooting up again, upward sweeps of up to 30 m (98 ft), with dive drops of up to at least 60 m (200 ft). These dances may be repeated in series of 10 to 20. In the climax of the sky dance, the undulations become progressive shallower, often slowing and terminating directly onto a perch. Various other aerial displays include low contour flight or weaving among trees, frequently with deep beats and exaggerated upstrokes which show underwing pattern to rivals perched below. Talon grappling and occasionally cartwheeling downward with feet interlocked has been recorded in buzzards and, as in many raptors, is likely the physical culmination of the aggressive territorial display, especially between males. Despite the highly territorial nature of buzzards and their devotion to a single mate and breeding ground each summer, there is one case of a polyandrous trio of buzzards nesting in the Canary Islands. In North-Estonian Neeruti landscape reserve (area 1272 ha) found in years 1989 and 1990 Marek Vahula 9 populated nest. This is sovereign public density of population. One nest founded in 12.06.1982 and this is apparently oldest nest of Common Buzzard, what is populated until today.

Common buzzards tend to build a bulky nest of sticks, twigs and often heather. Commonly, nests are up to 1 to 1.2 m (3 ft 3 in to 3 ft 11 in) across and 60 cm (24 in) deep. With reuse over years, the diameter can reach or exceed 1.5 m (4 ft 11 in) and weight of nests can reach over 200 kg (440 lb). Active nests tend to be lined with greenery, most often this consists of broad-leafed foliage but sometimes also includes rush or seaweed locally. Nest height in trees is commonly 3 to 25 m (9.8 to 82.0 ft), usually by main trunk or main crutch of the tree. In Germany, trees used for nesting consisted mostly of red beeches (Fagus sylvatica) (in 337 cases), whereas a further 84 were in assorted oaks. Buzzards were recorded to nest almost exclusively in pines in Spain at a mean height of 14.5 m (48 ft). Trees are generally used for a nesting location but they will also utilize crags or bluffs if trees are unavailable. Buzzards in one English study were surprisingly partial to nesting on well-vegetated banks and due to the rich surrounding environment habitat and prey population, were actually more productive than nests located in other locations here. Furthermore, a few ground nests were recorded in high prey-level agricultural areas in the Netherlands. In the Italian Alps, 81% of 108 nests were on cliffs. The common buzzard generally lacks the propensity of its Nearctic counterpart, the red-tailed hawk, to occasionally nest on or near manmade structures (often in heavily urbanized areas) but in Spain some pairs recorded nesting along the perimeter of abandoned buildings. Pairs often have several nests but some pairs may use one over several consecutive years. Two to four alternate nests in a territory is typical for common buzzards, especially those breeding further north in their range.

Chicks, juveniles & raise

The breeding season commences at differing times based on latitude. Common buzzard breeding seasons may fall as early as January to April but typically the breeding season is March to July in much of Palearctic. In the northern stretches of the range the breeding season may last into May–August. Mating usually occurs on or near the nest and lasts about 15 seconds, typically occurring several times a day. Eggs are usually laid in 2 to 3-day intervals. The clutch size can range from to 2 to 6, a relatively large clutch for an accipitrid. More northerly and westerly buzzard usually bear larger clutches, which average nearer 3, than those further east and south. In Spain, the average clutch size is about 2 to 2.3. From 4 locations in different parts of Europe, 43% had clutch size of 2, 41% had size of 3, clutches of 1 and 4 each constituted about 8%. Laying dates are remarkably constant throughout Great Britain.

There are, however, highly significant differences in clutch size between British study areas. These do not follow any latitudinal gradient and it is likely that local factors such as habitat and prey availability are more important determinants of clutch size. The eggs are white in ground colour, rather round in shape with sporadic red to brown markings sometimes lightly showing. In the nominate race, egg size is 49.8–63.8 mm (1.96–2.51 in) in height by 39.1–48.2 mm (1.54–1.90 in) in diameter with an average of 55 mm × 44 mm (2.2 in × 1.7 in) in 600 eggs. In the race of vulpinus, egg height is 48–63 mm (1.9–2.5 in) by 39.2–47.5 mm (1.54–1.87 in) with an average of 54.2 mm × 42.8 mm (2.13 in × 1.69 in) in 303 eggs. Eggs are generally laid in late March to early April in extreme south, sometime in April in most of Europe, into May and possibly even early June in the extreme north. If eggs are lost to a predator (including humans) or fail in some other way, common buzzards do not usually lay replacement clutches but they have been recorded, even with 3 attempts of clutches by a single female.The females does most but not all of the incubating, doing so for a total of 33–35 days.The female remains at the nest brooding the young in the early stages with the male bringing all prey. At about 8–12 days, both the male and female will bring prey but female continues to do all feeding until the young can tear up their own prey.

Once hatching commences, it may take 48 hours for the chick to chip out. Hatching may take place over 3–7 days, with new hatchlings averaging about 45 g (1.6 oz) in body mass.[2][16][4] Often the youngest nestling dies from starvation, especially in broods of three or more. In nestlings, the first down replaces by longer, coarser down at about 7 days of age with the first proper feathers appearing at 12 to 15 days. The young are nearly fully feathered rather than downy at about a month of age and can start to feed themselves as well. The first attempts to leave the nest are often at about 40–50 days, averaging usually 40–45 in nominate buzzards in Europe, but more quickly on average at 40–42 in vulpinus. Fledging occurs typically at 43–54 days but in extreme cases at as late 62 days. Sexual dimorphism is apparent in European fledglings, as females often scale about 1,000 g (2.2 lb) against 780 g (1.72 lb) in males.

After leaving the nest, buzzards generally stay close by, but with migratory ones there is more definitive movement generally southbound. Full independence is generally sought 6 to 8 weeks after fledging. 1st year birds generally remain in wintering area for following summer but then return to near area of origin but then migrate south again without breeding. Radio-tracking suggests that most dispersal, even relatively early dispersals, by juvenile buzzards is undertaken independently rather than via exile by parents, as has been recorded in some other birds of prey. In common buzzards, generally speaking, siblings stay quite close to each other after dispersal from their parents and form something of a social group, although parents usually tolerate their presence on their territory until they are laying another clutch. However, the social group of siblings disbands at about a year of age. Juvenile buzzards are subordinate to adults during most encounters and tend to avoid direct confrontations and actively defended territories until they are of appropriate age (usually at least 2 years of age).This was the case as well for steppe buzzard juveniles wintering in southern Africa, although in some cases juveniles were able to successfully steal prey from adults there.

Important Note:

This text is based on the article Common buzzard from the free encyclopedia Wikipedia and is licensed under the Creative Commons CC-BY-SA 3.0 Unported (short version). A list of the authors is available on Wikipedia.