Great Tit

Appearance

The Great Tit is large for a tit at 12.5–14.0 cm 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.

Naming

There are currently 14 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. 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.

Distribution

The Great Tit has a wide distribution across much of Eurasia. It is found across all of Europe except for Iceland and northern Scandinavia, including numerous Mediterranean islands. In North Africa it is found 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.

Habitat

The Great Tit occupies a range of habitats. It is most commonly found in open deciduous woodland, mixed forests and forest edges. In dense forests, including conifer forests it is usually found in forest clearings.

In northern Siberia it is found in boreal taiga. In North Africa it prefers 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 group in central Asia, 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.

Reproduction

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 to 15 days.

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 similarly to their parents. 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 6–7 g 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 to 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.

Food

Great Tits are primarily insectivorous in the summer, feeding on insects and spiders which they capture by foliage gleaning. Invertebrate prey that are taken include cockroaches, grasshoppers and crickets, lacewings, earwigs, bugs, ants, flies, caddis flies, beetles, scorpion flies, woodlice, 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, and include 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 pipistrelle bats. This is the first time a songbird has been seen to hunt 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.