The Eurasian blue tit (Cyanistes caeruleus) is a small passerine bird in the tit family, Paridae. It is easily recognised by its blue and yellow plumage and small size. Eurasian blue tits, usually resident and non-migratory birds, are widespread and a common resident breeder throughout temperate and subarctic Europe and parts of western Asia in deciduous or mixed woodlands, often with a high proportion of oak. They usually nest in tree holes, although they easily adapt to nest boxes where necessary. Their main rival for nests and in the search for food is the larger and sometimes more common great tit (Parus major). The Eurasian blue tit prefers insects and spiders for its diet. Outside the breeding season, they also eat seeds and other vegetable-based foods. The birds are noted for their acrobatic skills, as they can hold on to the outermost branches of trees and shrubs and hang upside down when looking for food.