# UKBirds

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## Blue Tit

### Cyanistes caeruleus

The Blue Tit (Cyanistes caeruleus or Parus caeruleus) is a small passerine bird in the tit family Paridae. The bird is easily recognisable by its blue and yellow plumage.
Blue tits, usually resident and non-migratory birds, are widespread and a common resident breeder throughout temperate and subarctic Europe and western Asia in deciduous or mixed woodlands with a high proportion of oak. They usually nest in tree holes, although they easily adapt to nest boxes where necessary. The main rival for nests and search for food is the much larger Great Tit.
The blue tit prefers insects and spiders for their diet. Outside the breeding season, they also eat seeds and other vegetable-based foods. Blue tits are famed for their skill, as they can cling to the outermost branches and hang upside down when looking for food.
The Blue Tit is usually 12 centimetres (4.7 in) long with a wingspan of 18 centimetres (7.1 in) for all genders, and weighs about 11 grams (0.39 oz).
A typical Blue Tit has an azure blue crown and dark blue line passing through the eye, and encircling the white cheeks to the chin, giving the bird a very distinctive appearance. The forehead and a bar on the wing are white. The nape, wings and tail are blue and the back is yellowish green. The underparts is mostly sulphur-yellow with a dark line down the abdomen - the yellowness is indicative of the number of yellowy-green caterpillars eaten, due to high levels of carotene pigments in the diet. The bill is black, the legs bluish grey, and the irides dark brown. The sexes are similar, but under ultraviolet light, males have a brighter blue crown. Young Blue Tits are noticeably more yellow.