Blue Tit
The Blue Tit, Cyanistes caeruleus, is a 10.5 to 12 cm long passerine bird in the tit family Paridae. It is a widespread and common resident breeder throughout temperate and subarctic Europe and western Asia in deciduous or mixed woodlands. It is a resident bird; i.e., most birds do not migrate. It will nest in any suitable hole in a tree, wall, or stump, or an artificial nest box, often competing with House Sparrows or Great Tits for the site. Few birds more readily accept the shelter of a nesting box; the same hole is returned to year after year, and when one pair dies another takes possession.
The Blue Tit is a close sitter, hissing and biting at an intruding finger. In the South West of England such behaviour has earned the Blue Tit the colloquial nickname "Little Billy Biter". When protecting its eggs it raises its crest, but this is a sign of excitement rather than anger, for it is also elevated during nuptial display. The nesting material is usually moss, wool, hair and feathers, and the eggs are laid in April or May. The number in the clutch is often very large, but seven or eight are normal, and bigger clutches are usually laid by two or even more hens.
Source:http://en.wikipedia.org/wiki/Blue_Tit - 02.10.2010