Common buzzard
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 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.
Taxonomy
The first formal description of the common buzzard was by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Falco buteo. The genus Buteo was introduced by the French naturalist Bernard Germain de Lacépède in 1799 by tautonymy with the specific name of this species. The word buteo is Latin for a buzzard. It should not be confused with the Turkey vulture, which is sometimes called a buzzard in American English.The Buteoninae subfamily originated from and is most diversified in the Americas, with occasional broader radiations that led to common buzzards and other Eurasian and African buzzards. The common buzzard is a member of the genus Buteo, a group of medium-sized raptors with robust bodies and broad wings. The Buteo species of Eurasia and Africa are usually commonly referred to as "buzzards" while those in the Americas are called hawks. Under current classification, the genus includes approximately 28 species, the second most diverse of all extant accipitrid genera behind only Accipiter. DNA testing shows that the common buzzard is fairly closely related to the red-tailed hawk of North America, which occupies a similar ecological niche to the buzzard in that continent. The two species may belong to the same species complex. Three buzzards in Africa are likely closely related to the common buzzard based on genetic materials, the Mountain buzzard, Forest buzzards and the Madagascar buzzard, to the point where it has been questioned whether they are sufficiently distinct to qualify as full species. However, the distinctiveness of these African buzzards has generally been supported. Genetic studies have further indicated that the modern buzzards of Eurasia and Africa are a relatively young group, showing that they diverged at about 300,000 years ago. Nonetheless, fossils dating earlier than 5 million year old showed Buteo species were present in Europe much earlier than that would imply, although it cannot be stated to a certainty that these would have been related to the extant buzzards.
Subspecies and species splits
Some 16 subspecies have been described in the past and up to 11 are often considered valid, although some authorities accept as few as seven. Common buzzard subspecies fall into two groups.The western buteo group is mainly resident or short-distance migrants and includes:
- B. b. buteo: Ranges in Europe from the Atlantic islands, the British Isles and the Iberian Peninsula more or less continuously throughout Europe to Finland, Romania and Asia Minor. This highly individually variable race is described below. This is a relatively large and bulky race of buzzard. In males, the wing chord ranges from and the tail from. In comparison, the larger female has a wing chord measuring and tail length of. In both sexes, the tarsus measures in length. As illustrated by average body mass, sizes in the nominate race of common buzzard seem to confirm to Bergmann's rule, increasing to the north and decreasing closer to the Equator. In southern Norway, the mean weight of males was reportedly, while that of females was. British buzzards were of intermediate size, 214 males averaging and 261 females averaging. Birds to the south in Spain were smaller, averaging in 22 males and in 30 females. Cramp and Simmons listed the mean body mass overall of nominate buzzards in Europe overall as in males and in females.
- B. b. rothschildi: This proposed race is native to the Azores islands. It is generally considered a valid subspecies. This race differs from a typical intermediate of the nominate in being a darker, colder brown both above and below, closer to the darker individuals of the nominate. It averages smaller than most nominate buzzards. The wing chord of males ranges from while that of females ranges from.
- B. b. insularum: This race lives in the Canary Islands. Not all authorities consider this race suitably distinct, but others advocate it be retained as a full subspecies. It is typically of richer brown above and more heavily streaked below compared to nominate birds. It is similar in size to B. b. rothschildi and averages slightly smaller than the nominate race. Males have a reported wing chord of and females have a wing chord of.
- B. b. arrigonii: This race inhabits the islands of Corsica and Sardinia. It is generally considered a valid subspecies. The upper-side of these buzzards is an intermediate brown with very heavy streaking below, often covering the belly whereas most nominate buzzards show a whitish area the middle of the belly. Like most other insular races, this one is relatively small. Males possess a wing chord of while females have a wing chord of.
- B. b. vulpinus: The steppe buzzard breeds as far west as eastern Sweden, in the southern two-thirds of Finland, eastern Estonia, much of Belarus and Ukraine, eastward to the northern Caucacus, northern Kazakhstan, Kyrgyzstan, much of Russia to Altai and south-central Siberia, Tien Shan in China and western Mongolia. B. b. vulpinus is a long-distance migrant. It winters largely in much of eastern and southern Africa. Less frequently and often very discontinuously, steppe buzzards winter in the southern peninsulas of Europe, Arabia and southwestern India in addition to some parts of southeastern Kazakhstan, Uzbekistan and Kyrgyzstan. In the open country favoured on the wintering grounds, steppe buzzards are often seen perched on roadside telephone poles. It at one time was considered a separate species due to differences in size, form, colouring and behaviour but is genetically indistinct from nominate buzzards. Furthermore, the steppe buzzard engages in extensive interbreeding with the nominate race, causing typical characteristics of the two races to mix. The zone of integration runs from Scandinavia through the European continent to the Black Sea, including any part of the overlapping ranges in Sweden, Finland, Estonia, Latvia, Lithuania, western Ukraine and eastern Romania. At times, the fertile hybrids of these two races have been erroneously proposed as races such as B. b. intermedius or B. b. zimmermannae. Intergrade buzzards are commonest where the grey-brown type of pale morphs of vulpinus are predominant. Steppe buzzards are usually distinctly smaller, with relatively longer wings and tail for their size, and thus often appear swifter and more agile in flight than nominate buzzards, whose wing beats can look slower and clumsier. Typically, their length is around, while wingspan of males average and females average. The wing chord is in males and in females. Tail length is in males and in females. Weights of birds from Russia can reportedly range from in males and in females. Weights of migrant birds appear to be lower than at other times of year for steppe buzzards. Two surveys of migrant buzzards during their huge spring movement in Eilat, Israel showed 420 birds averaged and 882 birds averaged. In comparison, weights of wintering steppe buzzards was higher, averaging in 35 birds in the former Transvaal and in 160 birds in the Cape Province. Weights of birds from Zambia were similar.
- B. b. menetriesi: This race is found in southern Crimea through the Caucasus to northern Iran and possibly into Turkey. This race has traditionally been listed as a resident race, but some sources consider it a migrant to eastern and southern Africa. Compared to the overlapping steppe buzzard subspecies, it is larger and is duller in overall colour, being sandy below rather than rufous and lacking the bright rufous on the tail. Wing chord is in males and in females.