Rough-legged buzzard | |
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Buteo lagopus lagopus, Sweden | |
Buteo lagopus sanctijohannis, Washington State | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Accipitriformes |
Family: | Accipitridae |
Genus: | Buteo |
Species: | B. lagopus |
Binomial name | |
Buteo lagopus (Pontoppidan, 1763) | |
Subspecies [2] | |
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Range of B. lagopus Summer Winter |
The rough-legged buzzard (Europe) or rough-legged hawk (North America) (Buteo lagopus) is a medium-large bird of prey. It is found in arctic and subarctic regions of North America, Europe, and Asia during the breeding season, and migrates south for the winter. [3] Historically, it was also known as "rough-legged falcon" [4] in such works as John James Audubon's The Birds of America .
Nests are typically located on cliffs, bluffs or in trees. The clutch sizes are variable with food availability, but usually three to five eggs are laid. [5] They hunt over open land, feeding primarily on small mammals, mainly lemmings and voles. [3] Along with the kestrels, kites, and osprey, this is one of the few birds of prey to hover regularly. [6]
This fairly large raptorial species is 46–68 cm (18–27 in) with wingspan ranging from 120 to 153 cm (47 to 60 in). [3] [7] Individuals can weigh from 600 to 1,660 g (1.32 to 3.66 lb) with females typically being larger and heavier than males. [8] [9] Weights appear to increase from summer to winter in adults, going from an average of 822 to 1,027 g (1.812 to 2.264 lb) in males and from 1,080 to 1,278 g (2.381 to 2.818 lb) in females. [10] [11] Among the members of the genus Buteo, it is sixth heaviest, the fifth longest, and the fourth longest winged. [12] Among standard measurements in adults, the wing chord is 37.2–48.3 cm (14.6–19.0 in), the tail is 18.6–25.5 cm (7.3–10.0 in), culmen is 3.2–4.5 cm (1.3–1.8 in) and the tarsus is 5.8–7.8 cm (2.3–3.1 in). [12] [13] [14] The plumage is predominantly brown and white, and often shows a high degree of speckling. [3] A broad brown chest-band is present in most plumages and a square dark carpal patch contrasting with the white under-wing is an easily identifiable characteristic in light morph individuals. [3] A wide variety of plumage patterns are exhibited in light vs. dark morphs, males vs. females, and adults vs. juveniles. Extensive field experience is required to distinguish between certain plumage variations. [10] Compared to its more common Palearctic and Nearctic cousins, the common buzzard (Buteo buteo) and the red-tailed hawk (Buteo jamaicensis), it is slightly larger, though may be outweighed by the latter.
Its legs are feathered, though not the toes, as an adaptation to cold in its Arctic home range. Its scientific name reflects this feature; the genus name Buteo is the Latin name of the common buzzard, and lagopus, is derived from Ancient Greek lago (λαγως), meaning "hare", and pous (πους), "foot". [15] [16] Its talons are relatively small, reflecting their preferred choice of prey.
Distinguishing characteristics in all plumages include long white tail feathers with one or more dark subterminal bands. The wing tips are long enough to reach or extend past the tail when it is perched. [3] The common buzzard can be similar-looking, with a similar long-tailed shape and can be notoriously variable in plumage; rough-legged is longer-winged and more eagle-like in appearance. The red-tailed hawk is chunkier-looking and differs in its darker head, broader, shorter wings, barring on the wings and the tail, dark leading edge to the wings (rather than black wrist patch) and has no white base to the tail. The ferruginous hawk is larger, with a bigger, more prominent bill and has a whitish comma at the wrist and all-pale tail. [17]
It is the only raptor of its size (other than the very different-looking osprey) to regularly hover over one spot, by beating its wings quickly.
The rough-legged buzzard is a member of the genus Buteo , a group of moderately large raptors exhibiting broad wings, short tails and wide robust bodies. [3] [18] This genus is known as buzzards in Europe but referred to as hawks in North America. [3]
Four subspecies of Buteo lagopus are accepted: [2]
The rough-legged buzzard breeds in tundra and taiga habitats of North America and Eurasia between the latitudes of 61° (locally south to 48° in Newfoundland and 58° N in southern Norway) and 76° N. Those occurring in North America migrate to southern Canada and into the central United States for the winter, while Eurasian birds migrate to central Europe and Asia, with small numbers west to eastern parts of Great Britain; most winter between latitudes of 43° and 58° N. It is the only member of its diverse genus found in all three of the northern continents, having a complete circumpolar distribution. During the winter months, from October to April, preferred habitats include marshes, moorland, prairies and agricultural regions where rodent prey is most abundant. [3] [19]
Breeding sites are usually located in areas with plenty of unforested, open ground. [5] Depending on snow conditions, migrants arrive at breeding grounds during April and May. [3] [19] . Home ranges vary with food supply but are commonly reported to be 10–15 km2 (3.9–5.8 sq mi) during the winter, but little is known about home ranges during the breeding season. [5] Although frequently attacked in skirmishes by other highly territorial birds such as gyrfalcons and skuas, the rough-legged buzzard is not strongly territorial. [3] However, wintering rough-legged buzzards may behave aggressively towards common buzzards in Sweden, and both species will try to keep the other off a fixed hunting range. [20]
This species is carnivorous, typically feeding on small mammals, which make up 62–98% of its diet. Lemmings and voles are the major prey items of this species, seasonally comprising up to 80–90% of their prey but this varies with seasonal availability. [3] [12] [21] Some evidence suggests that they may be able to see vole scent marks which are only visible in the ultraviolet range, allowing them to cue in on prey. [22] Despite generally preying on rodents, a 2015 paper reported the species breeding on rodent-free Kolguev Island in Arctic Russia with goslings as a main prey. [23] In northwest Russia, rough-legged buzzards may feed on small rodents in the years when rodent density is high, and shift to alternative prey (ptarmigans and hares) in the years when small rodents are scarce. [24] The rough-legged buzzard will also supplement its diet with mice, rats, gerbils, pikas, shrews, squirrels of the genera Spermophilus and Tamias , [25] and insects. [3] [21] Besides mammals, birds are the second-most favoured type of prey for rough-legged buzzards. Most avian prey species are small passerines such as snow bunting (Plectrophenax nivalis), Lapland longspur (Calcarius lapponicus), American tree sparrow (Spizelloides arborea) and thrushes (Turdus spp.). However, they will also prey on birds slightly larger than the passerines typically targeted, especially ptarmigan (Lagopus spp.) as well as waterfowl, waders such as dunlin (Calidris alpina) and ruff (Calidris pugnax) and even short-eared owl (Asio flammeus). They usually target young and inexperienced individuals, with relatively large avian prey often being fledglings. [12] [19] When small mammals are scarce, the rough-legged buzzard will also feed on larger, medium-sized mammals, including prairie dogs (Cynomys spp.), ground squirrels, muskrats (Ondatra zibethicus), weasels (Mustela spp.), and up to the size of black-tailed jackrabbits (Lepus californicus). [26] [27] During winter, shrub-steppe habitats seem to encourage a strong dependence on rabbit prey. [3] In developed areas of England, wintering rough-legged buzzards have been recorded preying most regularly on relatively large prey such as common woodpigeon (Columba palumbus) and invasive European rabbits (Oryctolagus cuniculus). [12]
This avian predator hunts opportunistically, occasionally supplementing its diet with carrion but focusing primarily on the most locally abundant small vertebrates. Rough-legged hawks will steal prey from other individuals of the same species as well as other species such as the red-tailed hawk, hen harrier (Circus cyaenus), American kestrel (Falco sparverius) and common raven (Corvus corax). [28] Prey sizes typically range from 6.5–2,587 g (0.23–91.25 oz) and adults require 80–120 g (2.8–4.2 oz) of food daily, around the body mass of the largest species of vole or lemming although most species weigh a bit less. [12] These raptors hunt during the daytime. [12] Like most Buteo species, rough-legged buzzards have been reported both still-hunting (watching for prey from a perch and then stooping) and watching for prey while in flight. Unlike most other large raptors, they may engage in hovering flight above the ground while searching for prey. [3]
Sexual maturity is reached at about two years old. Breeding generally occurs during May but is variable depending upon dates of arrival at breeding grounds. The rough-legged buzzard is thought to be monogamous, mating with a single individual for multiple years. [3] No evidence currently suggest otherwise.
Rough-legged buzzards look for suitable nesting territory not in spring, like most migratory birds, but in advance - in autumn. After the breeding season, they make long-distance prospecting flights, look for a suitable habitat with high rodent numbers, and return to that place the following year. [29]
Nests are built soon after arrival to breeding grounds and require 3–4 weeks to complete. Twigs, sedges, and old feathers are used as building materials. Nests are 60–90 cm (24–35 in) in diameter and 25–60 cm (9.8–23.6 in) in height. [3] Cliff ledges and rocky outcroppings are preferred nesting sites. Females can lay 1–7 eggs but will typically lay 3–5. [3] [5] Average egg size is 56.4 mm (2.22 in) in length by 44.7 mm (1.76 in) in width. Minimum incubation period is 31 days, provided almost exclusively by the female. The male feeds the female during this incubation period. After hatching, young require 4–6 weeks before fledging the nest. Fledglings depend on parents to provide food for 2–4 weeks after leaving the nest. [3]
Rough-legged buzzards may nest in association with peregrine falcons (Falco peregrinus). Peregrines chase away small rodent predators from their nesting territory and rough-legged buzzards could use these hot spots as a nesting territory. [30]
Rough-legged buzzards that survive to adulthood can live to an age of 19 years in the wild; however, perhaps a majority of individuals in the wild do not survive past their first two years of life. The threats faced by young rough-legs can include starvation when prey is not numerous, freezing when Northern conditions are particularly harsh during brooding, destruction by humans, and predation by various animals. The chances of survival increase incrementally both when they reach the fledging stage and when they can start hunting for themselves. Death of flying immatures and adults are often the result of human activity, including collisions with power lines, buildings, and vehicles, incidental ingestion of poison or lead from prey, or illegal hunting and trapping. [31]
Most predation recorded on this species is on the young at the nest. Arctic foxes (Vulpes lagopus), brown bears (Ursus arctos), and wolverines (Gulo gulo) will all eat eggs and young of this species if they are capable of accessing nests on foot. [32] Avian scavengers, especially groups of common ravens, will also readily prey on eggs and nestlings, as will skuas (Stercorarius spp.). Snowy owls (Bubo scandiacus) are a potential predator at the nest as well. [33] Adults, being a large raptorial bird, have fewer natural predators but may die in conflicts, especially if they are defending their own nests, and are occasionally preyed on by other large raptorial birds. Raptors which prey on rough-legged buzzards of most ages at varied times of year may include numerous eagles (especially the golden eagle (Aquila chrysaetos), though also sometimes other Aquila in Eurasia, but only rarely Haliaeetus eagles) as well as large falcons. While wintering, rough-legged buzzards or hawks may be vulnerable to predation by night to Eurasian eagle-owls (Bubo bubo) or great horned owls (Bubo virginianus) and rarely, during day, other large buzzards, including those of their own species. [3] [31] [34]
Besides predation, it could be other reasons for nestling mortality among rough-legged buzzards. Nestlings in their first two weeks have a lousy temperature regulation. In the tundra landscape, they nest on the ground and during hot weather, they could go out of the nest seeking shelter from the sun. If weather then rapidly changes to the thunderstorm (which is common in the Arctic) nestlings could die without parent protection in a short time in 3–5 m from the nest. [35] Other reasons for nestling mortality are earth-slides of the river-banks, where rough-legged buzzards often build their nests, and chilling. [36]
Adult rough-legged buzzards will give alarm calls when intruders approach a nesting site. It is described as a downward slurring whistle, sounding like kiu wiyuk or a lengthy descending kee-eer similar to that of the red-tailed hawk. This cry is given in flight or from a perch every 15–30 seconds. During courtship, both sexes have been recorded to give a whistling sound that changes to a hiss. Following copulation, females will give a cluck-like sound and males give a whistling noise. Fledglings will give begging calls while waiting for parents to provide food. [3]
The common buzzard is a medium-to-large bird of prey which has a large range. It is a member of the genus Buteo in the family Accipitridae. The species lives in most of Europe and extends its breeding range across much of the Palearctic as far as northwestern China, far western Siberia 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 journeying as far as South Africa.
The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds of prey with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a few feeding on fruit. The Accipitridae have a cosmopolitan distribution, being found on all the world's continents and a number of oceanic island groups. Some species are migratory. The family contains 256 species which are divided into 12 subfamilies and 75 genera.
Buteo is a genus of medium to fairly large, wide-ranging raptors with a robust body and broad wings. In the Old World, members of this genus are called "buzzards", but "hawk" is used in the New World. As both terms are ambiguous, buteo is sometimes used instead, for example, by the Peregrine Fund.
The eastern screech owl or eastern screech-owl, is a small owl that is relatively common in Eastern North America, from Mexico to Canada. This species resides in most types of woodland habitats across its range, and is relatively adaptable to urban and developed areas compared to other owls. Although it often lives in close proximity to humans, the eastern screech owl frequently avoids detection due to its strictly nocturnal habits.
The red-tailed hawk is a bird of prey that breeds throughout most of North America, from the interior of Alaska and northern Canada to as far south as Panama and the West Indies. It is one of the most common members within the genus of Buteo in North America or worldwide. The red-tailed hawk is one of three species colloquially known in the United States as the "chickenhawk", though it rarely preys on standard-sized chickens. The bird is sometimes also referred to as the red-tail for short, when the meaning is clear in context.
The ferruginous hawk is a large bird of prey and belongs to the broad-winged buteo hawks. An old colloquial name is ferrugineous rough-leg, due to its similarity to the closely related rough-legged hawk.
Harris's hawk, formerly known as the bay-winged hawk or dusky hawk, and known in Latin America as the peuco, is a medium-large bird of prey that breeds from the southwestern United States south to Chile, central Argentina, and Brazil. This bird is sometimes reported to be at large in Western Europe, especially Britain, but it is a popular species in falconry and these records almost invariably all refer to escapes from captivity.
The long-legged buzzard 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.
The zone-tailed hawk is a medium-sized hawk of warm, dry parts of the Americas. It is somewhat similar in plumage and flight style to a common scavenger, the turkey vulture, and may benefit from being able to blend into groups of vultures. It feeds on small terrestrial tetrapods of all kinds.
The Galápagos hawk is a large hawk endemic to most of the Galápagos Islands.
The black-chested buzzard-eagle is a bird of prey of the hawk and eagle family (Accipitridae). It lives in open regions of South America. This species is also known as the black buzzard-eagle, the gray buzzard-eagle, or analogously with "eagle" or "eagle-buzzard" replacing "buzzard-eagle", or as the Chilean blue eagle. It is sometimes placed in the genus Buteo.
The black-breasted buzzard is a large raptor endemic to mainland Australia. First described by John Gould in 1841, it forms part of the family Accipitridae and is most closely related to the square-tailed kite. It is a versatile hunter known for its special skill in cracking eggs. The species is common throughout most of its range.
The jackal buzzard is a fairly large African bird of prey. The taxonomy of this species has caused some confusion in the past and it almost certainly belongs in a species complex with other African Buteo species. Some taxonomists have considered this species, the Archer's buzzard, and the augur buzzard to be the same superspecies. Many taxonomists consider them all to be distinct, having different calls, different home ranges and variations in plumage. This is a species that lives among mountains, and on adjacent savanna and grassland. It is resident and non-migratory throughout its range.
The augur buzzard is a fairly large African bird of prey. This species is distinct in typical adult plumage for its blackish back, whitish underside and orange-red tail, while juvenile augur buzzards are generally rather brown in colour; however a dark morph is known, which causes the bird's entire body to become darker. This member of the Buteo genus is distributed in several parts of the central and southern Africa, normally being found from Ethiopia to southern Angola and central Namibia. It is resident and non-migratory throughout its range. This is a species of mountains, and adjacent savannah and grassland. This is a typical buteonine raptor, being a generalist predator which tends to prefer small mammals supplemented by reptiles and birds among various prey items.
The upland buzzard is a species of bird of prey in the family Accipitridae. The largest species of the Buteo genus, this buzzard lives in mountainous grassy and rocky areas in areas of Central Asia, northern South Asia and East Asia from Kazakhstan to Korea. The upland buzzard is migratory but typically covers a short distance apparently to avoid snow cover that may hamper prey capture. This species primarily subsists on small mammals but does not shun alternate prey from small to large birds and insects. This little known raptor has a large range, and though generally uncommon, it is not thought to be rare or declining as a species. As a result it is classified as least concern by the IUCN.
The variable hawk is a polymorphic species of bird of prey in the family Accipitridae.
The gyrfalcon, the largest of the falcon genus, is a bird of prey. The abbreviation gyr is also used. It breeds on Arctic coasts and tundra, and the islands of northern North America and the Eurosiberian region. It is mainly a resident there also, but some gyrfalcons disperse more widely after the breeding season, or in winter. Individual vagrancy can take birds for long distances. Its plumage varies with location, with birds being coloured from all-white to dark brown. These colour variations are called morphs. Like other falcons, it shows sexual dimorphism, with the female much larger than the male. For centuries, the gyrfalcon has been valued as a hunting bird. Typical prey includes the ptarmigan and waterfowl, which it may take in flight; it also takes fish and mammals.
The Eurasian goshawk is a species of medium-large bird of prey in the family Accipitridae, a family which also includes other extant diurnal raptors, such as eagles, buzzards and harriers. It was formerly placed in the genus Accipiter. It is a widespread species that inhabits many of the temperate parts of the Eurasia. Except in a small portion of southern Asia, it is the only species of "goshawk" in its range and it is thus often referred to, both officially and unofficially, as simply goshawk. It is mainly resident, but birds from colder regions migrate south for the winter. In 2023, the goshawks found in North America are no longer considered be conspecific, but are now designated as the American goshawk.
The red-shouldered hawk is a medium-sized buteo. Its breeding range spans eastern North America and along the coast of California and northern to northeastern-central Mexico. It is a permanent resident throughout most of its range, though northern birds do migrate, mostly to central Mexico. The main conservation threat to the widespread species is deforestation.
Swainson's hawk is a large bird species in the Accipitriformes order. This species was named after William Swainson, a British naturalist. It is colloquially known as the grasshopper hawk or locust hawk, as it is very fond of Acrididae and will voraciously eat these insects whenever they are available.