Common blackbird
The common blackbird is a species of true thrush. It is also known as the Eurasian blackbird, or simply the blackbird. It breeds in Europe, western Asia, and North Africa, and has been introduced to Australia and New Zealand. It has a number of subspecies across its large range; a few former Asian subspecies are now widely treated as separate species. Depending on latitude, the common blackbird may be resident, partially migratory, or fully migratory.
The adult male of the common blackbird, which is found throughout most of Europe, is all black except for a yellow eye-ring and bill and has a rich, melodious song. The adult female and juvenile have mainly dark brown plumage. This species breeds in woods and gardens, constructing neat, cup-shaped nests bound together with mud. It is omnivorous, eating a wide range of insects, earthworms, berries, and fruits.
Both sexes are territorial on the breeding grounds and have distinctive threat displays. However, they are more gregarious during migration and in wintering areas. Pairs remain in their territory throughout the year if the climate is sufficiently temperate. This common and conspicuous species has given rise to a number of literary and cultural references, often related to its song.
Taxonomy and systematics
The common blackbird was described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae as Turdus merula. The binomial name derives from two Latin words, turdus, "thrush", and merula, "blackbird", the latter giving rise to its French name, merle, and its Scots name, merl.The genus Turdus comprises around 65 species of medium to large thrushes, characterised by rounded heads, longish, pointed wings, and usually melodious songs. Two European thrushes, the song thrush and mistle thrush, diverged early from the Eurasian lineage of Turdus thrushes after spreading north from Africa. However, the blackbird is descended from ancestors that had colonised the Canary Islands from Africa and subsequently reached Europe from there. It is close in evolutionary terms to the island thrush of Southeast Asia and islands in the southwest Pacific, which probably diverged from T. merula stock fairly recently.
It may not immediately be clear why the name "blackbird", first recorded in 1486, was applied to this species and not to any of the various other common black birds found in England, such as the carrion crow, raven, rook, or jackdaw. In Old English, and in modern English up to about the 18th century, the word "bird" was used only for smaller or young birds, while larger ones such as crows were known as "fowl". At that time, the blackbird was therefore the only widespread and conspicuous "black bird" in the British Isles. Until about the 17th century, another name for the species was ouzel, ousel or wosel. Another variant occurs in Act 3 of William Shakespeare's A Midsummer Night's Dream, where Bottom refers to "The Woosell cocke, so blacke of hew, With Orenge-tawny bill". The ouzel usage survived later in poetry, and still occurs as the name of the closely related ring ouzel, and in water ouzel, an alternative name for the unrelated but superficially similar white-throated dipper.
Five related Asian Turdus thrushes—the white-collared blackbird, the grey-winged blackbird, the Indian blackbird, the Tibetan blackbird, and the Chinese blackbird —are also named blackbirds; the latter three species were formerly treated as conspecific with the common blackbird. In addition, the Somali thrush is alternatively known as the Somali blackbird.
The icterid family of the New World is sometimes called the blackbird family because some species superficially resemble to the common blackbird and other Old World thrushes. However, they are not evolutionarily close; they are actually related to the New World warblers and tanagers. The term is often limited to smaller species with mostly or entirely black plumage, at least in the breeding male, notably the cowbirds, the grackles, and for around 20 species with "blackbird" in the name, such as the red-winged blackbird and the melodious blackbird.
Subspecies
As expected for a widespread passerine bird species, several geographical subspecies are recognised. The treatment of subspecies in this article follows Clement et al..- T. m. merula, the nominate subspecies, breeds commonly throughout much of Europe from Iceland, the Faroes and the British Isles east to the Ural Mountains and north to about 70 N, where it is fairly scarce. A small population breeds in the Nile Valley. Birds from the north of the range winter throughout Europe and around the Mediterranean, including Cyprus and North Africa. The introduced birds in Australia and New Zealand are of the nominate race.
- T. m. azorensis is a small race which breeds in the Azores. The male is darker and glossier than merula.
- T. m. cabrerae, named for Ángel Cabrera, the Spanish zoologist, resembles azorensis and breeds in Madeira and the western Canary Islands.
- T. m. mauritanicus, another small dark subspecies with a glossy black male plumage, breeds in central and northern Morocco, coastal Algeria and northern Tunisia.
- T m. aterrimus breeds in Hungary, south and east to southern Greece, Crete, northern Turkey and northern Iran. It winters in southern Turkey, northern Egypt, Iraq and southern Iran. It is smaller than merula with a duller male and paler female plumage.
- T. m. syriacus breeds on the Mediterranean coast of southern Turkey south to Jordan, Israel and the northern Sinai. It is mostly resident, but part of the population moves southwest or west to winter in the Jordan Valley and in the Nile Delta of northern Egypt south to about Cairo. Both sexes of this subspecies are darker and greyer than the equivalent merula plumages.
- T. m. intermedius is an Asian race breeding from Central Russia to Tajikistan, western and northeastern Afghanistan, and eastern China. Many birds are resident, but some are altitudinal migrants and occur in southern Afghanistan and southern Iraq in winter. This is a large subspecies, with a sooty-black male and a blackish-brown female.
Similar species
In Europe, the common blackbird can be confused with the paler-winged first-winter ring ouzel or the superficially similar common starling. A number of similar Turdus thrushes exist far outside the range of the common blackbird, for example the South American Chiguanco thrush. The Indian blackbird, the Tibetan blackbird, and the Chinese blackbird were formerly treated as subspecies of the common blackbird.Description
The common blackbird of the nominate subspecies T. m. merula is in length, has a long tail, and weighs. The adult male has glossy black plumage, blackish-brown legs, a yellow eye-ring and an orange-yellow bill. Its bill darkens somewhat in winter. The adult female is sooty-brown with a dull yellowish-brownish bill, a brownish-white throat and some weak mottling on the breast. The juvenile is similar to the female, but has pale spots on its upperparts, and the very young juvenile also has a speckled breast. Young birds vary in shade of brown, darker birds are presumably male. The first year male resembles the adult male, but has a dark bill and weaker eye ring. Its folded wing is brown, rather than black like the body plumage.Distribution and habitat
The common blackbird breeds in temperate Eurasia, North Africa, the Canary Islands, and South Asia. It has also been introduced to Australia and New Zealand. Populations in the south and west of its range are sedentary, although northern birds migrate south as far as northern Africa and tropical Asia in winter. Urban males are more likely to overwinter in cooler climes than rural males, an adaptation made feasible by the warmer microclimate and relatively abundant food that allow the birds to establish territories and start reproducing earlier in the year. Recoveries of blackbirds ringed on the Isle of May show that these birds commonly migrate from southern Norway to Scotland, and some onwards to Ireland. Scottish-ringed birds have also been recovered in England, Belgium, the Netherlands, Denmark, and Sweden. Female blackbirds in Scotland and the north of England migrate more in winter than do the males.This species is common over most of its range in woodland and has a preference for deciduous trees with dense undergrowth. However, gardens provide the best breeding habitat, supporting up to 7.3 pairs per hectare, with woodland typically holding about a tenth of that density, and open and very built-up habitats even less. They are often replaced by the related ring ouzel in areas of higher altitude. The common blackbird also lives in parks, gardens and hedgerows.
The common blackbird occurs at elevations of up to in Europe, in North Africa, and at in peninsular India and Sri Lanka, but the large Himalayan subspecies range much higher, with T. m. maximus breeding at and remaining above even in winter.
This widespread species has been recorded as a vagrant in many locations outside of its normal range in Eurasia, but records from North America are usually thought to be of escaped birds, such as the bird recorded in Quebec in 1971. However, a 1994 record from Bonavista, Newfoundland, has been accepted as a genuine wild bird, and the species is therefore on the North American list.
Behaviour and ecology
The male common blackbird defends its breeding territory by chasing away other males or performing a "bow and run" threat display. This consists of a short run followed by the bird raising its and bowing it with its tail dipped simultaneously. If male blackbirds do fight, it is usually brief and the intruder is quickly chased away. The female blackbird is also aggressive in the spring when competing with other females for a good nesting territory. Although fights are less frequent, they tend to be more violent.The appearance of the bill is important in the interactions of the common blackbird. The male defending his territory responds more aggressively to models with orange bills than to those with yellow ones, and least of all to the brown bill colour typical of first-year males. However, the female is relatively indifferent to bill colour and instead responds to shinier bills.
As long as there is food available in winter, both male and females will remain in the territory throughout the year, although they will occupy different areas. Migrants are more sociable, travelling in small flocks and feeding in loose groups in their wintering grounds. The flight of migrating birds comprises bursts of rapid wing beats interspersed with level or diving movement. This differs from both the normal, fast, agile flight of this species, as well as the dipping action of larger thrushes.