Editing Common blackbird (section)

==Behaviour and ecology==
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.<ref name= Snow/>

The [[beak|bill]]'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.<ref name = AB64 >{{cite journal |last= Bright |first= Ashleigh |author2= Waas, Joseph R. |date= August 2002 |title= Effects of bill pigmentation and UV reflectance during territory establishment in blackbirds |journal= Animal Behaviour |volume= 64 |issue= 2 |pages= 207–213 |doi= 10.1006/anbe.2002.3042 |s2cid= 51833485 |url= http://cber.bio.waikato.ac.nz/images/bbposter2.pdf |access-date= 2007-12-16 |archive-url= https://web.archive.org/web/20110929203122/http://cber.bio.waikato.ac.nz/images/bbposter2.pdf |archive-date= 2011-09-29 |url-status= dead }}</ref>

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.<ref name= BWP/>

===Breeding===
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.<ref name = Snow/> This species is monogamous, and the established pair will usually stay together as long as they both survive.<ref name = BWP/> Pair separation rates of up to 20% have been noted following poor breeding.<ref>{{cite journal |journal=Ibis |volume=143 |issue=4 |pages=554–560 |last=Streif |first=Michael |author2=Rasa O. Anne E.|year=2001|title=Divorce and its consequences in the Common blackbird ''Turdus merula''|doi=10.1111/j.1474-919X.2001.tb04882.x}}</ref> Although the species is socially monogamous, there have been studies showing as much as 17% extra-pair paternity.<ref>{{cite journal|journal=Behavioral Ecology|volume=15|issue=3|pages=508–519|year=2004|title=Extrapair paternity and the evolution of bird song|first=László Zsolt|last=Garamszegia|author2=Anders Pape Møller|doi=10.1093/beheco/arh041|doi-access=free}}</ref>

The nominate ''T. 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).<ref name=Clement/><ref name= Observerbirdseggs/> The breeding pair prospect for a suitable nest site in a creeper or bush, favouring evergreen or thorny species such as [[ivy]], [[holly]], [[crataegus|hawthorn]], [[honeysuckle]] or [[pyracantha]].<ref name = NatEngland/> Sometimes the birds will nest in sheds or outbuildings where a ledge or cavity is used. The cup-shaped [[bird nest|nest]] 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-green [[Bird egg|eggs]] marked with reddish-brown blotches,<ref name = Snow/> heaviest at the larger end;<ref name=Observerbirdseggs/> the eggs of nominate ''T. merula'' are {{cvt|2.9|×|2.1|cm|in}} in size and weigh {{cvt|7.2|g|oz}}, of which 6% is shell.<ref name = BTO>{{cite web|title= Blackbird ''Turdus merula'' [Linnaeus, 1758] |work= BTOWeb BirdFacts|url= http://blx1.bto.org/birdfacts/results/bob11870.htm |publisher=British Trust for Ornithology |access-date=30 December 2007}}</ref> Eggs of birds of the southern Indian races are paler than those from the northern subcontinent and Europe.<ref name = Clement/>

The female incubates for 12–14 days before the [[altricial]] 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.<ref name = BWP/> The nest is often ill-concealed compared with those of other species, and many breeding attempts fail due to predation.<ref name="Game and Wildfowl Conservation Trust">{{cite web|title= 89% of Blackbird nest failures are attributed to predators | url= http://www.gwct.org.uk/about_us/news/1212.asp| publisher= Game and Wildfowl Conservation Trust |access-date=23 January 2012}}</ref> 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.<ref name = Snow/> 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.<ref name = Clement/>

A common blackbird has an average [[life expectancy]] of 2.4 years,<ref>{{cite web |url=http://www.garden-birds.co.uk/information/lifespan.htm |title=British garden birds – lifespan |access-date=7 April 2007 |publisher=garden-birds.co.uk |archive-url=https://web.archive.org/web/20070424192443/http://www.garden-birds.co.uk/information/lifespan.htm |archive-date=2007-04-24 |url-status=dead }}</ref> and, based on data from [[bird ringing]], the oldest recorded age is 21 years and 10 months.<ref>{{cite web |url=http://www.euring.org/data_and_codes/longevity-voous.htm |title= European Longevity Records |access-date=15 December 2007 |publisher=euring.org}}</ref>

<gallery widths="200" heights="160">
File:Eurasian blackbird (Turdus merula) female with nesting material South Bruny.jpg|Female with nesting material
File:Blackbird nest with 3 eggs.jpg|Eggs in a nest
File:Turdus merula -England -chicks in nest-8 (2).jpg|Two chicks in a nest
File:Blackbird Fledgelings 2020 a 60 fps.webm|Blackbird fledgelings being fed
File:Male Turdus merula feeding chicks.ogv|Male feeding chicks
File:02-Common Blackbird 1-Jan-2023 nX.webm|Common blackbird foraging in Norfolk, England
File:Turdus merula (AU)-full.webm|A common blackbird eating figs near Toulouse, France
File:Blackbird feeding.mpg|Feeding chick and removing faecal sac
</gallery>

===Songs and calls===
{| class="wikitable" align="right"
|[[File:Turdus merula 2.ogg|90px|noicon|left]] [[:File:Turdus merula 2.ogg|Song 1]]
|-
|[[File:Turdus merula (06 02 16).ogg|90px|noicon|left]] [[:File:Turdus merula (06 02 16).ogg|Song 2]]
|-
|[[File:Turdus merula.ogg|90px|noicon|left]] [[:File:Turdus merula.ogg|Song 3]]
|-
|[[File:Common Blackbird (Turdus merula) (W1CDR0001425 BD22).ogg|90px|noicon|left]] [[:File:Common Blackbird (Turdus merula) (W1CDR0001425 BD22).ogg|Song 4]]
|-
|[[File:Common Blackbird (Turdus merula) (W1CDR0001525 BD22).ogg|90px|noicon|left]] [[:File:Common Blackbird (Turdus merula) (W1CDR0001525 BD22).ogg|Alarm calls]]
|}

In its native [[Northern 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<ref>{{Cite web |title=Blackbird - learn its song and calls |url=https://www.birdsong.academy/species-guide/blackbird |access-date=2024-05-20 |website=Birdsong Academy |language=en-US}}</ref> mainly in the period from March to June, sometimes into the beginning of July. It has a number of other calls, including an aggressive ''seee'', a ''pook-pook-pook'' alarm for terrestrial predators like cats, and various ''chink'' and ''chook, chook'' vocalisations. The territorial male invariably gives ''chink-chink'' calls in the evening in an attempt (usually unsuccessful) to deter other blackbirds from roosting in its territory overnight.<ref name=Snow/> 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.<ref name=gbirds>{{cite web | title=Blackbird | url=http://www.garden-birds.co.uk/birds/blackbird.htm | publisher=British Garden Birds | access-date=4 January 2016 | archive-url=https://web.archive.org/web/20160109153322/http://www.garden-birds.co.uk/birds/blackbird.htm | archive-date=2016-01-09 | url-status=dead }}</ref> Like other passerine birds, it has a thin high ''seee'' alarm call for threats from [[bird of prey|birds of prey]] since the sound is rapidly attenuated in vegetation, making the source difficult to locate.<ref name= burton>{{cite book| last = Burton| first = Robert| title = Bird behaviour| year = 1985| location = London| publisher = Granada| page = [https://archive.org/details/birdbehaviour0000burt/page/125 125]| isbn = 0-246-12440-7| url = https://archive.org/details/birdbehaviour0000burt/page/125}}</ref>

The nominate subspecies ''T. 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.<ref>{{Cite web |title=Blackbird: bird song and calls {{!}} Sussex Wildlife Trust |url=https://sussexwildlifetrust.org.uk/news/blackbird-bird-song-and-calls |access-date=2025-02-25 |website=sussexwildlifetrust.org.uk}}</ref>

===Feeding===
[[File:Male common blackbird with feed in Lausanne.jpg|thumb|Adult male feeding on cherries in [[Lausanne]], Switzerland]]
The common blackbird is [[omnivorous]], eating a wide range of insects, [[earthworm]]s, 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 through [[leaf litter]] for other [[invertebrate]]s. Small [[amphibian]]s, lizards and (on rare occasions) small [[mammal]]s are occasionally hunted.<ref>{{Cite web|title=We watched a blackbird kill and then fly away with a shrew. Is this unusual?|url=https://www.rspb.org.uk/birds-and-wildlife/bird-and-wildlife-guides/ask-an-expert/previous/blackbirdandshrew.aspx|access-date=2021-04-16|website=The RSPB|language=en}}</ref><ref>{{Cite news|last=Elliott|first=Valerie|title=Birds get taste for tadpoles as summer heat keeps worms under ground|newspaper=[[The Times]]|language=en|url=https://www.thetimes.com/travel/destinations/uk-travel/england/london-travel/birds-get-taste-for-tadpoles-as-summer-heat-keeps-worms-under-ground-jcf99p8q68p|access-date=2021-04-16|issn=0140-0460}}</ref> This species will also perch in bushes to take berries and collect [[caterpillar]]s and other active insects.<ref name= Snow/> 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.

===Natural threats===
[[File:Blackbird and Kestrel.jpg|upright|thumb|A male blackbird attempting to distract a male [[Common kestrel|kestrel]] 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 the [[Eurasian sparrowhawk|sparrowhawk]] and other [[accipiter]]s, also take this species when the opportunity arises.<ref name=RSPB/><ref name=Lambeth>{{cite web |title= Blackbird Action Plan |url= http://www.lambeth.gov.uk/NR/rdonlyres/A862EBE6-4CD7-4317-9B64-D0FB565AAF1C/0/BAPSummaryBlackbird.pdf |publisher= Lambeth Council's Parks and Greenspaces Business Unit |access-date= 11 December 2007 |url-status= dead |archive-url= https://web.archive.org/web/20071005010251/http://www.lambeth.gov.uk/NR/rdonlyres/A862EBE6-4CD7-4317-9B64-D0FB565AAF1C/0/BAPSummaryBlackbird.pdf |archive-date= 5 October 2007 }}</ref> However, there is little direct evidence to show that either predation of the adult blackbirds or loss of the eggs and chicks to [[Corvidae|corvids]], such as the [[European magpie]] or [[Eurasian jay]], decrease population numbers.<ref name=NatEngland>{{cite web |title = Blackbird – ''Turdus merula'' |url = http://www.joyofplants.com/wildlife/search.php?o=30 |publisher = The Royal Horticultural Society/The Wildlife Trusts |access-date = 9 April 2012 |url-status = dead |archive-url = https://web.archive.org/web/20131029203048/http://www.joyofplants.com/wildlife/search.php?o=30 |archive-date = 29 October 2013 }}</ref>

This species is occasionally a host of [[brood parasite|parasitic]] [[cuckoo]]s, such as the [[common cuckoo]] (''Cuculus canorus''), but this is minimal because the common blackbird recognizes the adult of the parasitic species and its [[mimicry|non-mimetic]] eggs.<ref name = daviesnb>{{cite journal | last1=Davies | first1=N. B. | last2=Brooke | first2= M. de L. | year=1989 | title= An experimental study of co-evolution between the Cuckoo, ''Cuculus canorus'', and its hosts. I. Host egg discrimination | journal= Journal of Animal Ecology | volume=58 | issue=1 | pages=207–224 | jstor=4995 | doi=10.2307/4995| bibcode=1989JAnEc..58..207D }}</ref> In the UK, only three nests of 59,770 examined (0.005%) contained cuckoo eggs.<ref name= glue>{{cite journal |last= Glue |first=David |author2=Morgan, Robert |year=1972 |title= Cuckoo hosts in British habitats | journal= Bird Study | volume= 19| pages=187–192 |doi=10.1080/00063657209476342|issue=4|bibcode=1972BirdS..19..187G }}</ref> The introduced ''merula'' 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.<ref name=JAB>{{cite journal|last=Hale|first=Katrina|author2=Briskie, James V.|date=March 2007|title=Response of introduced European birds in New Zealand to experimental brood parasitism|journal=Journal of Avian Biology|volume=38|issue=2|pages=198–204|issn=0908-8857|doi=10.1111/j.2007.0908-8857.03734.x|url=http://www.biology.ualberta.ca/courses.hp/biol506.hp/pdfs/Hale07_JAvBi_BroodParasitism.pdf|access-date=2012-01-16|archive-url=https://web.archive.org/web/20120113014727/http://www.biology.ualberta.ca/courses.hp/biol506.hp/pdfs/Hale07_JAvBi_BroodParasitism.pdf|archive-date=2012-01-13|url-status=dead}}</ref>

As with other passerine birds, parasites are common. [[Intestinal parasite]]s were found in 88% of common blackbirds, most frequently ''[[Isospora]]'' and ''[[Capillaria (nematode)|Capillaria]]'' species.<ref>{{cite book|last=Misof|first=Katharina|url=http://hss.ulb.uni-bonn.de:90/2005/0661/0661.pdf|title=Eurasian Blackbirds (''Turdus merula'') and their gastrointestinal parasites: A role for parasites in life-history decisions?|publisher=Doctoral dissertation, Bonn|year=2005|url-status=dead|archive-url=https://web.archive.org/web/20110719101955/http://hss.ulb.uni-bonn.de:90/2005/0661/0661.pdf|archive-date=2011-07-19}}</ref> and more than 80% had haematozoan parasites (''[[Leucocytozoon]]'', ''[[Plasmodium]]'', ''[[Haemoproteus]]'' and ''[[Trypanosoma]]'' species).<ref>{{cite journal |author1=Hatchwell, B. J. |author2=Wood |author3=Anwar, M. J. M. |author4=Perrins C. M. |url=http://www.nrcresearchpress.com/doi/abs/10.1139/z99-228?journalCode=cjz |title=The prevalence and ecology of the haematozoan parasites of European blackbirds, ''Turdus merula'' |journal=Canadian Journal of Zoology |volume=78 |issue=4 |pages=684–687 |year=2000 |doi=10.1139/cjz-78-4-684|url-access=subscription }}</ref>

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.<ref name= Gregoire/> In France, 74% of rural blackbirds were found to be infested with ''[[Ixodes]]'' ticks, whereas, only 2% of blackbirds living in urban habitats were infested.<ref name= Gregoire/> 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.<ref name= Gregoire/> Although ixodid ticks can transmit [[pathogen]]ic viruses and bacteria, and are known to transmit ''[[Borrelia]]'' bacteria to birds,<ref name= Kipp>{{cite journal|last= Kipp|first= Susanne |author2=Goedecke, Andreas|author3=Dorn, Wolfram|author4=Wilske, Bettina|author5=Fingerle, Volke |date=May 2006|title=Role of birds in Thuringia, Germany, in the natural cycle of ''Borrelia burgdorferi'' sensu lato, the Lyme disease spirochaete |journal= [[International Journal of Medical Microbiology]]|pmid= 16530003|volume= 296|pages= 125–128 |doi=10.1016/j.ijmm.2006.01.001 }}</ref> there is no evidence that this affects the fitness of blackbirds except when they are exhausted and run down after migration.<ref name=Gregoire>{{cite journal |last=Gregoire |first=Arnaud |author2=Faivre, Bruno |author3=Heeb, Philipp |author4=Cezilly, Frank |year=2002 |title=A comparison of infestation patterns by ''Ixodes ''ticks in urban and rural populations of the Common Blackbird ''Turdus merula'' |url=http://www.cefe.cnrs.fr/esp/publis/AG/AGGregoire%20et%20al%202002%20Ibis.pdf |journal=Ibis |volume=144 |issue=4 |pages=640–645 |doi=10.1046/j.1474-919X.2002.00102.x |url-status=dead |archive-url=https://web.archive.org/web/20081217155251/http://www.cefe.cnrs.fr/esp/publis/AG/AGGregoire%20et%20al%202002%20Ibis.pdf |archive-date=2008-12-17 }}</ref>

The common blackbird is one of a number of species which has [[unihemispheric slow-wave sleep]]. One hemisphere of the brain is effectively asleep, while a low-voltage [[Electroencephalography|EEG]], 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.<ref name="Perspectives">{{cite journal |last1=Rattenbourg |first1=Neils C. |last2=Amlaner |first2=C. J. |last3=Lima |first3=S.L. |title=Behavioral, neurophysiological and evolutionary perspectives on unihemispheric sleep |journal=Neuroscience and Biobehavioral Reviews |volume=24 |pages=817–842 |year=2000 |pmid=11118608 |doi=10.1016/S0149-7634(00)00039-7 |issue=8|s2cid=7592942 }}</ref>