Common resident. Inhabits the deciduous, mixed and coniferous forests, groves and shelterbelts on plains and in mountains at altitudes up to 1300-1400 m. Pairs are formed in February-March. Breeds in separate pairs far one from another. Nest is located in tree hole (natural or bored by Woodpecker; in poplar, elm, willow, birch), in cavities of human construction, or in nest-boxes at height up to 5 m above the ground; nest is built from dry grass, rootlets and moss and is lined with plenty of hair and feathers. Clutch of 7-15 eggs is laid in mid-April to early July. Female builds nest for 4-10 days and incubates clutch for 11-14 days. Both parents feed juveniles which fledges in end of May to end of August. Female begins to lay the second clutch before 1-2 days or after 1-2 days of fledging of first offspring. Rears two broods per season, re-nesting after loss of first clutch is common. Most of the year lives in small groups of 3-10 birds.