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Facts & Profile
Great tit Parus major

The great tit (Parus major) is a passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central and east across the Palearctic to the Amur River, south to parts of North Africa where it is generally resident in any sort of woodland; most great tits do not migrate except in extremely harsh winters. Until 2005 this species was lumped with numerous other subspecies. DNA studies have shown these other subspecies to be distinctive from the great tit and these have now been separated as two distinct species, the cinereous tit of southern Asia, and the Japanese tit of East Asia. The great tit remains the most widespread species in the genus Parus.

The great tit is a distinctive bird with a black head and neck, prominent white cheeks, olive upperparts and yellow underparts, with some variation amongst the numerous subspecies. It is predominantly insectivorous in the summer, but will consume a wider range of food items in the winter months, including small hibernating bats. Like all tits it is a cavity nester, usually nesting in a hole in a tree. The female lays around 12 eggs and incubates them alone, although both parents raise the chicks. In most years the pair will raise two broods. The nests may be raided by woodpeckers, squirrels and weasels and infested with fleas, and adults may be hunted by sparrowhawks. The great tit has adapted well to human changes in the environment and is a common and familiar bird in urban parks and gardens. The great tit is also an important study species in ornithology.

Description & appearance

The great tit is large for a tit at 12.5 to 14.0 cm (4.9–5.5 in) in length, and has a distinctive appearance that makes it easy to recognise. The nominate race P. major major has a bluish-black crown, black neck, throat, bib and head, and white cheeks and ear coverts. The breast is bright lemon-yellow and there is a broad black mid-line stripe running from the bib to vent. There is a dull white spot on the neck turning to greenish yellow on the upper nape. The rest of the nape and back are green tinged with olive. The wing-coverts are green, the rest of the wing is bluish-grey with a white wing-bar. The tail is bluish grey with white outer tips. The plumage of the female is similar to that of the male except that the colours are overall duller; the bib is less intensely black, as is the line running down the belly, which is also narrower and sometimes broken. Young birds are like the female, except that they have dull olive-brown napes and necks, greyish rumps, and greyer tails, with less defined white tips.
There is some variation in the subspecies. P. m. newtoni is like the nominate race but has a slightly longer bill, the mantle is slightly deeper green, there is less white on the tail tips, and the ventral mid-line stripe is broader on the belly. P. m. corsus also resembles the nominate form but has duller upperparts, less white in the tail and less yellow in the nape. P. m. mallorcae is like the nominate subspecies, but has a larger bill, greyer-blue upperparts and slightly paler underparts. P. m. ecki is like P. m. mallorcae except with bluer upperparts and paler underparts. P. m. excelsus is similar to the nominate race but has much brighter green upperparts, bright yellow underparts and no (or very little) white on the tail. P. m. aphrodite has darker, more olive-grey upperparts, and the underparts are more yellow to pale cream. P. m. niethammeri is similar to P. m. aphrodite but the upperparts are duller and less green, and the underparts are pale yellow. P. m. terrasanctae resembles the previous two subspecies but has slightly paler upperparts.

P. m. blandfordi is like the nominate but with a greyer mantle and scapulars and pale yellow underparts, and P. m. karelini is intermediate between the nominate and P. m. blandfordi, and lacks white on the tail. The plumage of P. m. bokharensis is much greyer, pale creamy white to washed out grey underparts, a larger white cheep patch, a grey tail, wings, back and nape. It is also slightly smaller, with a smaller bill but longer tail. The situation is similar for the two related subspecies in the Turkestan tit group. P. m. turkestanicus is like P. m. bokharensis but with a larger bill and darker upperparts. P. m. ferghanensis is like P. m. bokharensis but with a smaller bill, darker grey on the flanks and a more yellow wash on the juvenile birds.

The colour of the male bird's breast has been shown to correlate with stronger sperm, and is one way that the male demonstrates his reproductive superiority to females. Higher levels of carotenoid increase the intensity of the yellow of the breast its colour, and also enable the sperm to better withstand the onslaught of free radicals. Carotenoids cannot be synthesized by the bird and have to be obtained from food, so a bright colour in a male demonstrates his ability to obtain good nutrition. The width of the male's ventral stripe, which varies with individual, is selected for by females, with higher quality females apparently selecting males with wider stripes.

Voice, singing & call

The great tit is, like other tits, a vocal bird, and has up to 40 types of calls and songs. The calls are generally the same between the sexes, but the male is much more vocal and the female rarely calls. Soft single notes such as "pit", "spick", or "chit" are used as contact calls. A loud "tink" is used by adult males as an alarm or in territorial disputes. One of the most familiar is a "teacher, teacher", often likened to a squeaky wheelbarrow wheel, which is used in proclaiming ownership of a territory. In former times, English folk considered the "saw-sharpening" call to be a foretelling of rain. There is little geographic variation in calls, but tits from the two south Asian groups recently split from the great tit do not recognise or react to the calls of the temperate great tits.

One explanation for the great tit's wide repertoire is the Beau Geste hypothesis. The eponymous hero of the novel propped dead soldiers against the battlements to give the impression that his fort was better defended than was really the case. Similarly, the multiplicity of calls gives the impression that the tit's territory is more densely occupied than it actually is. Whether the theory is correct or not, those birds with large vocabularies are socially dominant and breed more successfully.

Distribution & habitat

The great tit has a wide distribution across much of Eurasia. It can be found across all of Europe except for Iceland and northern Scandinavia, including numerous Mediterranean islands. In North Africa it lives in Morocco, Algeria and Tunisia. It also occurs across the Middle East, and parts of Central Asia from northern Iran and Afghanistan to Mongolia, as well as across northern Asia from the Urals as far east as northern China and the Amur Valley.

The great tit occupies a range of habitats. It is most commonly found in open deciduous woodland, mixed forests, forest edges and gardens. In dense forests, including conifer forests it prefers forest clearings. In northern Siberia it lives in boreal taiga. In North Africa it rather resides in oak forests as well as stands of Atlas cedar and even palm groves. In the east of its range in Siberia, Mongolia and China it favours riverine willow and birch forest. Riverine woodlands of willows, poplars are among the habitats of the Turkestan subspecies, as well as low scrubland, oases; at higher altitudes it occupies habitats ranging from dense deciduous and coniferous forests to open areas with scattered trees.

The great tit is generally not migratory. Pairs will usually remain near or in their territory year round, even in the northern parts of their range. Young birds will disperse from their parents' territory, but usually not far. Populations may become irruptive in poor or harsh winters, meaning that groups of up to a thousand birds may unpredictably move from northern Europe to the Baltic and also to Netherlands, Britain, even as far as the southern Balkans.

The great tit was unsuccessfully introduced into the United States; birds were set free near Cincinnati, Ohio between 1872 and 1874 but failed to become established. Suggestions that they were an excellent control measure for codling moths nearly led to their introduction to some new areas particularly in the United States of America, however this plan was not implemented. Birds were later introduced to the Almaty Province in what is now Kazakhstan in 1960–61 and became established, although their present status is unclear.

Hunting & food

Great tits are primarily insectivorous in the summer, feeding on insects and spiders which they capture by foliage gleaning. Their larger invertebrate prey include cockroaches, grasshoppers and crickets, lacewings, earwigs, bugs (Hemiptera), ants, flies (Diptera), caddis flies, beetles, scorpion flies, harvestmen, bees and wasps, snails and woodlice. During the breeding season, the tits prefer to feed protein-rich caterpillars to their young. A study published in 2007 found that great tits helped to reduce caterpillar damage in apple orchards by as much as 50%. Nestlings also undergo a period in their early development where they are fed a number of spiders, possibly for nutritional reasons. In autumn and winter, when insect prey becomes scarcer, great tits add berries and seeds to their diet. Seeds and fruit usually come from deciduous trees and shrubs, like for instance the seeds of beech and hazel. Where it is available they will readily take table scraps, peanuts and sunflower seeds from bird tables. In particularly severe winters they may consume 44% of their body weight in sunflower seeds. They often forage on the ground, particularly in years with high beech mast production. Great tits, along with other tits, will join winter mixed-species foraging flocks.

Large food items, such as large seeds or prey, are dealt with by "hold-hammering", where the item is held with one or both feet and then struck with the bill until it is ready to eat. Using this method, a great tit can get into a hazelnut in about twenty minutes. When feeding young, adults will hammer off the heads off large insects to make them easier to consume, and remove the gut from caterpillars so that the tannins in the gut will not retard the chick's growth.

Great tits combine dietary versatility with a considerable amount of intelligence and the ability to solve problems with insight learning, that is to solve a problem through insight rather than trial and error. In England, great tits learned to break the foil caps of milk bottles delivered at the doorstep of homes to obtain the cream at the top. This behaviour, first noted in 1921, spread rapidly in the next two decades. In 2009, great tits were reported killing, and eating the brains of roosting pipistrelle bats. This is the first time a songbird has been recorded preying on bats. The tits only do this during winter when the bats are hibernating and other food is scarce. They have also been recorded using tools, using a conifer needle in the bill to extract larvae from a hole in a tree.

Breeding & mating

Great tits are monogamous breeders and establish breeding territories. These territories are established in late January and defence begins in late winter or early spring. Territories are usually reoccupied in successive years, even if one of the pair dies, so long as the brood is raised successfully. Females are likely to disperse to new territories if their nest is predated the previous year. If the pair divorces for some reason then the birds will disperse, with females travelling further than males to establish new territories. Although the great tit is socially monogamous, extra-pair copulations are frequent. One study in Germany found that 40% of nests contained some offspring fathered by parents other than the breeding male and that 8.5% of all chicks were the result of cuckoldry.

Great tits are seasonal breeders. The exact timing of breeding varies by a number of factors, most importantly location. Most breeding occurs between January and September; in Europe the breeding season usually begins after March. In Israel there are exceptional records of breeding during the months of October to December. The amount of sunlight and daytime temperatures will also affect breeding timing. One study found a strong correlation between the timing of laying and the peak abundance of caterpillar prey, which is in turn correlated to temperature. On an individual level, younger females tend to start laying later than older females.

Great tits are cavity nesters, breeding in a hole that is usually inside a tree, although occasionally in a wall or rock face, and they will readily take to nest boxes. The nest inside the cavity is built by the female, and is made of plant fibres, grasses, moss, hair, wool and feathers. The number in the clutch is often very large, as many as 18, but five to twelve is more common. Clutch size is smaller when birds start laying later, and is also lower when the density of competitors is higher. Second broods tend to have smaller clutches. Insularity also affects clutch size, with great tits on offshore islands laying smaller clutches with larger eggs than mainland birds. The eggs are white with red spots. The female undertakes all incubation duties, and is fed by the male during incubation. The bird is a close sitter, hissing when disturbed. The timing of hatching, which is best synchronised with peak availability of prey, can be manipulated when environmental conditions change after the laying of the first egg by delaying the beginning of incubation, laying more eggs or pausing during incubation. The incubation period is between 12 and 15 days.

Chicks, juveniles & raise

The chicks, like those of all tits, are hatched unfeathered and blind. Once feathers begin to erupt, the nestlings are unusual for altricial birds in having plumage coloured with carotenoids similar to their parents (in most species it is dun-coloured to avoid predation). The nape is yellow and attracts the attention of the parents by its ultraviolet reflectance. This may be to make them easier to find in low light, or be a signal of fitness to win the parents' attention. This patch turns white after the first moult at age two months, and diminishes in size as the bird grows.

Chicks are fed by both parents, usually receiving 6 to 7 g (0.21–0.25 oz) of food a day. Both parents provision the chicks with food and aid in nest sanitation by removing faecal packets, with no difference in the feeding effort between the sexes. The nestling period is between 16 and 22 days, with chicks being independent of the parents eight days after fledging. Feeding of the fledgeling may continue after independence, lasting up to 25 days in chicks from the first brood, but as long as 50 days in the second brood. Nestlings from second broods have weaker immune systems and body condition than those from first broods, and hence have a lower juvenile survival rate.

Inbreeding depression occurs when the offspring produced as a result of a mating between close relatives show reduced fitness. The reduced fitness is generally considered to be a consequence of the increased expression of deleterious recessive alleles in these offspring. In natural populations of P. major, inbreeding is avoided by dispersal of individuals from their birthplace, which reduces the chance of mating with a close relative.

Important Note:

This text is based on the article Great tit from the free encyclopedia Wikipedia and is licensed under the Creative Commons CC-BY-SA 3.0 Unported (short version). A list of the authors is available on Wikipedia.