The Common Blackbird (Turdus merula) is a species of true thrush. It is also called Eurasian Blackbird (especially in North America, to distinguish it from the unrelated New World blackbirds), or simply Blackbird, where this does not lead to confusion with a similar-looking local species. It breeds in Europe, 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 of the Asian subspecies are sometimes considered to be full species. Depending on latitude, the Common Blackbird may be resident, partially migratory or fully migratory.
The male of the nominate subspecies, 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, building a neat, mud-lined, cup-shaped nest. It is omnivorous, eating a wide range of insects, earthworms, berries, and fruits.
Both sexes are territorial on the breeding grounds, with distinctive threat displays, but are more gregarious during migration and in wintering areas. Pairs will stay in their territory throughout the year where the climate is sufficiently temperate. This common and conspicuous species has given rise to a number of literary and cultural references, frequently related to its song.
The Common Blackbird was described by Linnaeus in the 10th edition of his Systema Naturae in 1758 as Turdus merula (characterised as T. ater, rostro palpebrisque fulvis). 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. There are about 65 species of medium to large thrushes in the genus Turdus, characterised by rounded heads, longish pointed wings, and usually melodious songs. The Common Blackbird seems to be closest in evolutionary terms to the Island Thrush (T. poliocephalus) of Southeast Asia and islands in the southwest Pacific, which probably diverged from merula stock fairly recently.
It may not immediately be clear why the name "Blackbird", first recorded in 1486, was applied to this species, but not to one of the various other common black English birds, such as the Carrion Crow, Raven, Rook or Jackdaw. However, in Old English, and in modern English up to about the 18th century, "bird" was used only for smaller or young birds, and larger ones such as crows were called "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 (from Old English osle). Another variant occurs in Act 3 of 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 (Turdus torquatus), and in Water Ouzel, an alternative name for the unrelated but superficially similar White-throated Dipper (Cinclus cinclus).