Great tit


The great tit is a small passerine bird in the tit family Paridae. It is widespread and common throughout Europe, the Middle East, Central Asia and as far east as the Amur River. It also occurs in 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. However, DNA studies have revealed that these subspecies are distinct from the great tit, and they have now been classified 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-coloured upperparts and yellow underparts. There is some variation amongst the numerous subspecies. Predominantly insectivorous in the summer, the species consumes 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 tree hole. 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. However, the nests may be raided by woodpeckers, squirrels and weasels and may become infested with fleas, and adults may be hunted by sparrowhawks. The great tit has adapted well to human-induced environmental changes and is a common and familiar bird in urban parks and gardens. The great tit is also an important study species in ornithology.

Taxonomy

The great tit was first described under its current binomial name by Carl Linnaeus in his 1758 10th edition of Systema Naturae. Its scientific name is derived from the Latin parus "tit" and maior "larger". Francis Willughby had used the name in the 17th century.
The great tit was formerly considered to range from Britain to Japan and south to the islands of Indonesia, with 36 described subspecies ascribed to four main species groups. The major group comprised 13 subspecies across Europe, temperate Asia and north Africa; the minor group's nine subspecies occurred from southeast Russia and Japan into northern southeast Asia and the 11 subspecies in the cinereus group were found from Iran across south Asia to Indonesia. The three bokharensis subspecies were often treated as a separate species, Parus bokharensis, the Turkestan tit. This form was once thought to form a ring species around the Tibetan Plateau, with gene flow throughout the subspecies, but this theory was abandoned when sequences of mitochondrial DNA were examined, finding that the four groups were distinct and that the hybridisation zones between the groups were the result of secondary contact after a temporary period of isolation.
A study published in 2005 confirmed that the major group was distinct from the cinereus and minor groups and that along with P. m. bokharensis it diverged from these two groups around 1.5 million years ago. The divergence between the bokharensis and major groups was estimated to have been about half a million years ago. The study also examined hybrids between representatives of the major and minor groups in the Amur Valley where the two meet. Hybrids were rare, suggesting that there were some reproductive barriers between the two groups. The study recommended that the two eastern groups be split out as new species, the cinereous tit, and the Japanese tit, but that the Turkestan tit be lumped in with the great tit. This taxonomy has been followed by some authorities, for example the IOC World Bird List. The Handbook of the Birds of the World volume treating the Parus species went for the more traditional classification, treating the Turkestan tit as a separate species but retaining the Japanese and cinereous tits with the great tit, a move that has not been without criticism.
The nominate subspecies of the great tit is the most widespread, its range stretching from the Iberian Peninsula to the Amur Valley and from Scandinavia to the Middle East. The other subspecies have much more restricted distributions; four are confined to islands, while the rest of the P. m. major subspecies represent former glacial refuge populations. The dominance of a single, morphologically uniform subspecies over such a large area suggests that the nominate race rapidly recolonised a large area after the last glacial epoch. This hypothesis is supported by genetic studies which suggest a geologically recent genetic bottleneck followed by a rapid population expansion.
The genus Parus once held most of the species of tit in the family Paridae, but morphological and genetic studies led to the splitting of that large genus in 1998. The great tit was retained in Parus, which along with Cyanistes comprises a lineage of tits known as the "non-hoarders", with reference to the hoarding behaviour of members of the other clade. The genus Parus is still the largest in the family, but may be split again. Other than those species formerly considered to be subspecies, the great tit's closest relatives are the white-naped and green-backed tits of southern Asia. Hybrids with tits outside the genus Parus are very rare, but have been recorded with blue tit, coal tit, and probably marsh tit.

Subspecies

There are currently 15 recognised subspecies of great tit:
  • P. m. newtoni, described by Pražák in 1894, is found across the British Isles.
  • P. m. major, described by Linnaeus in 1758, is found throughout much of Europe, Asia Minor, northern and eastern Kazakhstan, southern Siberia and northern Mongolia, as far as the mid-Amur Valley.
  • P. m. excelsus, described by Buvry in 1857, is found in northwestern Africa.
  • P. m. corsus, described by Kleinschmidt in 1903, is found in Portugal, southern Spain, and Corsica.
  • P. m. mallorcae, described by von Jordans in 1913, is found in the Balearic Islands.
  • P. m. ecki, described by von Jordans in 1970, is found on Sardinia.
  • P. m. niethammeri, described by von Jordans in 1970, is found on Crete.
  • P. m. aphrodite, described by Madarász in 1901, is found in southern Italy, southern Greece, Cyprus and the Aegean Islands.
  • P. m. terrasanctae was described by Hartert in 1910. It is found in Lebanon, Israel, Jordan and Syria.
  • P. m. karelini, described by Zarudny in 1910, is found in southeastern Azerbaijan and northwestern Iran.
  • P. m. blandfordi was described by Pražák in 1894. It is found in north central and southwestern Iran.
  • P. m. bokharensis was described by Lichtenstein in 1823. It is found in southern Kazakhstan, Uzbekistan, Turkmenistan and far north of Iran and Afghanistan. It was, along with following two subspecies, once treated as separate species.
  • P. m. turkestanicus, was described by Zarudny & Loudon in 1905, and ranges from east Kazakhstan to extreme north west China and west Mongolia.
  • P. m. ferghanensis, was described by Buturlin in 1912, and is found in Tajikistan and Kyrgyzstan.
  • P. m. kapustini, was described by Portenko in 1954, and is found in north west China to Mongolia and Siberia.

    Description

The great tit is large for a tit at 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 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. However, the saturation of the yellow colour is also influenced by environmental factors, such as weather conditions. 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.