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Thecommon blackbird (Turdus merula) is a species oftrue thrush. It is also called theEurasian blackbird (especially in North America, to distinguish it from the unrelatedNew World blackbirds),[3] or simply theblackbird. It breeds in Europe, western Asia, and North Africa, and has beenintroduced to Australia and New Zealand.[4] It has a number ofsubspecies across its large range; a few former Asian subspecies are now widely treated as separate species. Depending onlatitude, the common blackbird may beresident, partiallymigratory, or fully migratory.
The adult male of the common blackbird (Turdus merula merula, thenominate subspecies), which is found throughout most of Europe, is all black except for a yellow eye-ring andbill and has a rich, melodioussong; the adult female and juvenile have mainly dark brownplumage. This species breeds in woods and gardens, building a neat, cup-shaped nest, bound together with mud. It isomnivorous, eating a wide range of insects,earthworms,berries, and fruits.
Both sexes areterritorial on the breeding grounds, with distinctive threat displays, but are more gregarious during migration and in wintering areas. Pairs stay in their territory throughout the year where the climate is sufficientlytemperate. 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 byCarl Linnaeus in his landmark 175810th edition ofSystema Naturae asTurdus merula (characterised asT. ater, rostro palpebrisque fulvis).[5] The binomial name derives from twoLatin words,turdus, "thrush", andmerula, "blackbird", the latter giving rise to its French name,merle,[6] and itsScots name,merl.[7]
About 65 species of medium to large thrushes are in the genusTurdus, characterised by rounded heads, longish, pointed wings, and usually melodious songs. Although two European thrushes, thesong thrush andmistle thrush, are early offshoots from the Eurasian lineage ofTurdus thrushes after they spread north from Africa, the blackbird is descended from ancestors that had colonised theCanary Islands from Africa and subsequently reached Europe from there.[8] It is close in evolutionary terms to theisland thrush (T. poliocephalus) of Southeast Asia and islands in the southwest Pacific, which probably diverged fromT. merula stock fairly recently.[9]
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 thecarrion crow,raven,rook, orjackdaw. However, inOld English, and inmodern 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.[10] Until about the 17th century, another name for the species wasouzel,ousel orwosel (from Old Englishosle, cf. GermanAmsel). Another variant occurs in Act 3 ofWilliam Shakespeare'sA Midsummer Night's Dream, whereBottom 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 relatedring ouzel (Turdus torquatus), and in water ouzel, an alternative name for the unrelated but superficially similarwhite-throated dipper (Cinclus cinclus).[11]
Theicterid family of the New World is sometimes called the blackbird family because of some species' superficial resemblance to the common blackbird and other Old World thrushes, but they are not evolutionarily close, being related to theNew World warblers andtanagers.[14] The term is often limited to smaller species with mostly or entirely black plumage, at least in the breeding male, notably thecowbirds,[15] thegrackles,[16] and for around 20 species with "blackbird" in the name, such as thered-winged blackbird and themelodious blackbird.[14]
As would be expected for a widespread passerine bird species, several geographical subspecies are recognised. The treatment of subspecies in this article follows Clement et al. (2000).[9]
T. m. merula, the nominate subspecies, breeds commonly throughout much of Europe fromIceland, theFaroes and the British Isles east to theUral Mountains and north to about 70 N, where it is fairly scarce. A small population breeds in theNile Valley. Birds from the north of the range winter throughout Europe and around the Mediterranean, includingCyprus and North Africa. The introduced birds in Australia and New Zealand are of the nominate race.[9]
T. m. azorensis is a small race which breeds in theAzores. The male is darker and glossier thanmerula.[17]
T. m. mauritanicus, another small dark subspecies with a glossy black male plumage, breeds in central and northernMorocco, coastalAlgeria and northernTunisia.[17]First-summer male, probably subspeciesaterrimus
T m. aterrimus breeds in Hungary, south and east to southern Greece,Crete, northernTurkey and northernIran. It winters in southern Turkey, northernEgypt,Iraq and southern Iran. It is smaller thanmerula with a duller male and paler female plumage.[17]
T. m. syriacus breeds on the Mediterranean coast of southern Turkey south toJordan, Israel and the northernSinai. It is mostly resident, but part of the population moves southwest or west to winter in theJordan Valley and in theNile Delta of northern Egypt south to aboutCairo. Both sexes of this subspecies are darker and greyer than the equivalentmerula plumages.[9]
T. m. intermedius is an Asian race breeding from Central Russia toTajikistan, 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.[9] This is a large subspecies, with a sooty-black male and a blackish-brown female.[18]
The Central Asian subspecies, the relatively largeintermedius, also differs in structure and voice, and may represent a distinct species.[18] Alternatively, it has been suggested that it should be considered a subspecies ofT. maximus,[9] but it differs in structure, voice and the appearance of the eye-ring.[18][19]
In Europe, the common blackbird can be confused with the paler-winged first-winterring ouzel (Turdus torquatus) or the superficially similarcommon starling (Sturnus vulgaris).[20] A number of similarTurdus thrushes exist far outside the range of the common blackbird, for example the South AmericanChiguanco thrush (Turdus chiguanco).[21] TheIndian blackbird (Turdus simillimus), theTibetan blackbird (Turdus maximus), and theChinese blackbird (Turdus mandarinus) were formerly treated as subspecies of the common blackbird.[12]
The common blackbird of thenominate subspeciesT. m. merula is 23.5–29 cm (9.3–11.4 in) in length, has a long tail, and weighs 80–125 g (2.8–4.4 oz). The adult male has glossy blackplumage, blackish-brown legs, a yellow eye-ring and an orange-yellowbill. The bill darkens somewhat in winter.[20] The adult female is sooty-brown with a dull yellowish-brownish bill, a brownish-white throat and some weak mottling on the breast. Thejuvenile is similar to the female, but has pale spots on the upperparts, and the very young juvenile also has a speckled breast. Young birds vary in the shade of brown, with darker birds presumably males.[20] The first year male resembles the adult male, but has a dark bill and weaker eye ring, and its folded wing is brown, rather than black like the body plumage.[9]
The common blackbird breeds in temperate Eurasia, North Africa, theCanary Islands, and South Asia. It has been introduced to Australia and New Zealand.[9] Populations aresedentary in the south and west of the range, although northern birdsmigrate south as far as northern Africa and tropical Asia in winter.[9] Urban males are more likely tooverwinter 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.[22] Recoveries of blackbirds ringed on theIsle of May show that these birds commonly migrate from southern Norway (or from as far north asTrondheim) to Scotland, and some onwards to Ireland. Scottish-ringed birds have also been recovered in England, Belgium, the Netherlands, Denmark, and Sweden.[23] Female blackbirds in Scotland and the north of England migrate more (to Ireland) in winter than do the males.[24]
Common over most of its range in woodland, the common blackbird has a preference for deciduous trees with dense undergrowth. However, gardens provide the best breeding habitat with up to 7.3 pairs per hectare (nearly three pairs per acre), with woodland typically holding about a tenth of that density, and open and very built-up habitats even less.[25] They are often replaced by the relatedring ouzel in areas of higher altitude.[26] The common blackbird also lives in parks, gardens and hedgerows.[27]
The common blackbird occurs at elevations of up to 1,000 m (3,300 ft) in Europe, 2,300 m (7,500 ft) in North Africa, and at 900–1,820 m (2,950–5,970 ft) in peninsular India and Sri Lanka, but the large Himalayan subspecies range much higher, withT. m. maximus breeding at 3,200–4,800 m (10,500–15,700 ft) and remaining above 2,100 m (6,900 ft) even in winter.[9]
This widespread species has occurred as a vagrant in many locations in Eurasia outside its normal range, but records from North America are normally considered to involve escapees, including, for example, the 1971 bird inQuebec.[28] However, a 1994 record fromBonavista, Newfoundland, has been accepted as a genuine wild bird,[9] and the species is therefore on theNorth American list.[29]
The male common blackbird defends its breeding territory, chasing away other males or utilising a "bow and run" threat display. This consists of a short run, the head first being raised and then bowed with the tail dipped simultaneously. If a fight between male blackbirds does occur, it is usually short and the intruder is soon chased away. The female blackbird is also aggressive in the spring when it competes with other females for a good nesting territory, and although fights are less frequent, they tend to be more violent.[25]
Thebill's appearance is important in the interactions of the common blackbird. The territory-holding male responds more aggressively towards models with orange bills than to those with yellow bills, and reacts least to the brown bill colour typical of the first-year male. The female is, however, relatively indifferent to bill colour, but responds instead to shinier bills.[30]
As long as winter food is available, both the male and female will remain in the territory throughout the year, although occupying different areas. Migrants are more gregarious, travelling in small flocks and feeding in loose groups in the wintering grounds. The flight of migrating birds comprises bursts of rapid wing beats interspersed with level or diving movement, and differs from both the normal fast agile flight of this species and the more dipping action of larger thrushes.[17]
The male common blackbird attracts the female with a courtship display which consists of oblique runs combined with head-bowing movements, an open beak, and a "strangled" low song. The female remains motionless until she raises her head and tail to permit copulation.[25] This species is monogamous, and the established pair will usually stay together as long as they both survive.[17] Pair separation rates of up to 20% have been noted following poor breeding.[31] Although the species is socially monogamous, there have been studies showing as much as 17% extra-pair paternity.[32]
The nominateT. merula may commence breeding in March, but eastern and Indian races are a month or more later, and the introduced New Zealand birds start nesting in August (late winter).[9][26] The breeding pair prospect for a suitable nest site in a creeper or bush, favouring evergreen or thorny species such asivy,holly,hawthorn,honeysuckle orpyracantha.[33] Sometimes the birds will nest in sheds or outbuildings where a ledge or cavity is used. The cup-shapednest is made with grasses, leaves and other vegetation, bound together with mud. It is built by the female alone. She lays three to five (usually four) bluish-greeneggs marked with reddish-brown blotches,[25] heaviest at the larger end;[26] the eggs of nominateT. merula are 2.9 cm × 2.1 cm (1.14 in × 0.83 in) in size and weigh 7.2 g (0.25 oz), of which 6% is shell.[34] Eggs of birds of the southern Indian races are paler than those from the northern subcontinent and Europe.[9]
The female incubates for 12–14 days before thealtricial chicks are hatched naked and blind. Fledging takes another 10–19 (average 13.6) days, with both parents feeding the young and removing faecal sacs.[17] The nest is often ill-concealed compared with those of other species, and many breeding attempts fail due to predation.[35] The young are fed by the parents for up to three weeks after leaving the nest, and will follow the adults begging for food. If the female starts another nest, the male alone will feed the fledged young.[25] Second broods are common, with the female reusing the same nest if the brood was successful, and three broods may be raised in the south of the common blackbird's range.[9]
A common blackbird has an averagelife expectancy of 2.4 years,[36] and, based on data frombird ringing, the oldest recorded age is 21 years and 10 months.[37]
Female with nesting material
Eggs in a nest
Two chicks in a nest
Blackbird fledgelings being fed
Male feeding chicks
Common blackbird foraging in Norfolk, England
A common blackbird eating figs near Toulouse, France
In its nativeNorthern Hemisphere range, the first-year male common blackbird of the nominate race may start singing as early as late January in fine weather in order to establish a territory, followed in late March by the adult male. The male's song is a varied and melodious low-pitched fluted warble, given from trees, rooftops or other elevated perches[38] mainly in the period from March to June, sometimes into the beginning of July. It has a number of other calls, including an aggressiveseee, apook-pook-pook alarm for terrestrial predators like cats, and variouschink andchook, chook vocalisations. The territorial male invariably giveschink-chink calls in the evening in an attempt (usually unsuccessful) to deter other blackbirds from roosting in its territory overnight.[25] During the northern winter, blackbirds can be heard quietly singing to themselves, so much so that September and October are the only months in which the song cannot be heard.[39] Like other passerine birds, it has a thin highseee alarm call for threats frombirds of prey since the sound is rapidly attenuated in vegetation, making the source difficult to locate.[40]
The nominate subspeciesT. m. merula is known to mimic sounds in the local environment, including the songs of other birds, as well as human sounds and technology such as whistling and car alarms.[41]
Adult male feeding on cherries inLausanne, Switzerland
The common blackbird isomnivorous, eating a wide range of insects,earthworms, seeds and berries. It feeds mainly on the ground, running and hopping with a start-stop-start progress. It pulls earthworms from the soil, usually finding them by sight, but sometimes by hearing, and roots throughleaf litter for otherinvertebrates. Smallamphibians, lizards and (on rare occasions) smallmammals are occasionally hunted.[42][43] This species will also perch in bushes to take berries and collectcaterpillars and other active insects.[25] Animal prey predominates, and is particularly important during the breeding season, with windfall apples and berries taken more in the autumn and winter. The nature of the fruit taken depends on what is locally available, and frequently includes exotics in gardens.
A male blackbird attempting to distract a malekestrel close to its nest
Near human habitation the main predator of the common blackbird is the domestic cat, with newly fledged young especially vulnerable. Foxes and predatory birds, such as thesparrowhawk and otheraccipiters, also take this species when the opportunity arises.[44][45] However, there is little direct evidence to show that either predation of the adult blackbirds or loss of the eggs and chicks tocorvids, such as theEuropean magpie orEurasian jay, decrease population numbers.[33]
This species is occasionally a host ofparasiticcuckoos, such as thecommon cuckoo (Cuculus canorus), but this is minimal because the common blackbird recognizes the adult of the parasitic species and itsnon-mimetic eggs.[46] In the UK, only three nests of 59,770 examined (0.005%) contained cuckoo eggs.[47] The introducedmerula blackbird in New Zealand, where the cuckoo does not occur, has, over the past 130 years, lost the ability to recognize the adult common cuckoo but still rejects non-mimetic eggs.[48]
Common blackbirds spend much of their time looking for food on the ground where they can become infested with ticks, which are external parasites that most commonly attach to the head of a blackbird.[51] In France, 74% of rural blackbirds were found to be infested withIxodes ticks, whereas, only 2% of blackbirds living in urban habitats were infested.[51] This is partly because it is more difficult for ticks to find another host on lawns and gardens in urban areas than in uncultivated rural areas, and partly because ticks are likely to be commoner in rural areas, where a variety of tick hosts, such as foxes, deer and boar, are more numerous.[51] Although ixodid ticks can transmitpathogenic viruses and bacteria, and are known to transmitBorrelia bacteria to birds,[52] there is no evidence that this affects the fitness of blackbirds except when they are exhausted and run down after migration.[51]
The common blackbird is one of a number of species which hasunihemispheric slow-wave sleep. One hemisphere of the brain is effectively asleep, while a low-voltageEEG, characteristic of wakefulness, is present in the other. The benefit of this is that the bird can rest in areas of high predation or during long migratory flights, but still retain a degree of alertness.[53]
The common blackbird has an extensive range, estimated at 32.4 million square kilometres (12.5 million square miles), and a large population, including an estimated 79 to 160 million individuals in Europe alone. The species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations), and is therefore evaluated asleast concern.[54] In the westernPalearctic, populations are generally stable or increasing,[17] but there have been local declines, especially on farmland, which may be due to agricultural policies that encouraged farmers to remove hedgerows (which provide nesting places), and to drain damp grassland and increase the use ofpesticides, both of which could have reduced the availability of invertebrate food.[44]
The common blackbird was introduced to Australia by a bird dealer visitingMelbourne in early 1857,[55] and its range has expanded from its initial foothold in Melbourne andAdelaide to include all of southeastern Australia, includingTasmania and theBass Strait islands.[56] The introduced population in Australia is considered a pest because it damages a variety of soft fruits in orchards, parks and gardens, including berries, cherries, stone fruit and grapes.[55] It is thought to spread weeds, such asblackberry, and may compete with native birds for food and nesting sites.[55][57]
The introduced common blackbird is, together with the nativesilvereye (Zosterops lateralis), the most widely distributed avian seed disperser in New Zealand. Introduced there along with thesong thrush (Turdus philomelos) in 1862, it has spread throughout the country up to an elevation of 1,500 metres (4,921 ft), as well as outlying islands such as theCampbell andKermadecs.[58] It eats a wide range of native and exotic fruit, and makes a major contribution to the development of communities of naturalised woody weeds. These communities provide fruit more suited to non-endemic native birds and naturalised birds than toendemic birds.[59]
The numbers of blackbirds in Europe have been significantly reduced by theUsutu virus which is spread by mosquitoes. This was detected in Italy in 1996 and has since spread to other countries including Germany and the UK.[60][61]
The common blackbird was seen as a sacred though destructive bird in Classical Greek folklore, and was said to die if it consumedpomegranates.[62] Like many other small birds, it has in the past been trapped in rural areas at its night roosts as an easily available addition to the diet,[63] and in medieval times the practice of placing live birds under a pie crust just before serving may have been the origin of the familiarnursery rhyme:[63]
Sing a song of sixpence, A pocket full of rye; Four and twenty blackbirds baked in a pie! When the pie was opened the birds began to sing,
Oh, wasn't that a dainty dish to set before the king?[64]
The common blackbird's melodious, distinctive song is mentioned in the poemAdlestrop byEdward Thomas;
And for that minute a blackbird sang
Close by, and round him, mistier, Farther and farther, all the birds
In the EnglishChristmas carol "The Twelve Days of Christmas", the line commonly sung today as "four calling birds" is believed to have originally been written in the 18th century as "four colly birds", anarchaism meaning "black as coal" that was a popular English nickname for the common blackbird.[66]
The common blackbird, unlike many black creatures, is not normally seen as a symbol of bad luck,[63] butR. S. Thomas wrote that there is "a suggestion of dark Places about it",[67] and it symbolised resignation in the 17th centurytragic playThe Duchess of Malfi;[68] an alternate connotation is vigilance, the bird's clear cry warning of danger.[68]
The common blackbird is thenational bird of Sweden,[69] which has a breeding population of 1–2 million pairs,[17] and was featured on a 30 öre Christmas postage stamp in 1970;[70] it has also featured on a number of other stamps issued by European and Asian countries, including a 1966 4d British stamp and a 1998 Irish 30p stamp.[71] This bird—arguably—also gives rise to theSerbian name forKosovo (and Metohija), which is the possessive adjectival form of Serbiankos ("blackbird") as inKosovo Polje ("Blackbird Field").[72]
French composerOlivier Messiaen transcribed the songs of male blackbirds; these melodies have commonly appeared throughout his œuvre. The most notable instance of this is the 1952 chamber miniatureLe merle noir, a piece for flute and piano.
^abcdefghiSnow, David; Perrins, Christopher M., eds. (1998).The Birds of the Western Palearctic concise edition (2 volumes). Oxford: Oxford University Press.ISBN0-19-854099-X. p1215–1218
^abcCollar, N. J. (2005). Common Blackbird (Turdus merula). p. 645 in: del Hoyo, J., Elliott, A., & Christie, D. A. eds. (2005)Handbook of the Birds of the World. Vol. 10. Cuckoo-shrikes to Thrushes. Lynx Edicions, Barcelona.ISBN84-87334-72-5
^Collar, N. J. (2005). Tibetan Blackbird (Turdus maximus). p. 646 in: del Hoyo, J., Elliott, A., & Christie, D. A., eds. (2005).Handbook of the Birds of the World. Vol. 10:Cuckoo-shrikes to Thrushes. Lynx Edicions, Barcelona.ISBN84-87334-72-5
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^Streif, Michael; Rasa O. Anne E. (2001). "Divorce and its consequences in the Common blackbirdTurdus merula".Ibis.143 (4):554–560.doi:10.1111/j.1474-919X.2001.tb04882.x.
^ab"Threats".Blackbird. Royal Society for the Protection of Birds. Retrieved19 December 2007.
^"Blackbird Action Plan"(PDF). Lambeth Council's Parks and Greenspaces Business Unit. Archived fromthe original(PDF) on 5 October 2007. Retrieved11 December 2007.
^Davies, N. B.; Brooke, M. de L. (1989). "An experimental study of co-evolution between the Cuckoo,Cuculus canorus, and its hosts. I. Host egg discrimination".Journal of Animal Ecology.58 (1):207–224.Bibcode:1989JAnEc..58..207D.doi:10.2307/4995.JSTOR4995.
^abcClarke, G. M.; Gross, S., Matthews, M.; Catling, P. C.; Baker, B.; Hewitt, C. L.; Crowther, D.; Saddler, S. R. (2000),Environmental Pest Species in Australia, Australia: State of the Environment, Second Technical Paper Series (Biodiversity), Department of the Environment and Heritage, Canberra.hdl:102.100.100/203987
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^"Blackbird". Department of Agriculture, Western Australia. 16 December 2014. Retrieved17 August 2017.
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