The Blue Tit (Cyanistes caeruleus) is a 10.5 to 12 cm (4.2 to 4.8 inches,) 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.