Tit′mouse, the common name of a number of small birds related to the warblers. There are about 75 species, found chiefly in the Old World. Four species inhabit the eastern United States. The commonest of these is the well-known black-capped chickadee, which is a winter as well as a summer resi-ident in the southern part of its range. This bird is about five inches long, gray above and white below washed with brown. The crown and throat are black and the cheeks white. Its familiar call is chickadee, and besides this it has a high, sweet whistle of two or more notes. It ranges from Labrador to Indiana and Virginia. In the south it is replaced by a smaller southern chickadee. The tufted titmouse is the largest of the American species, being about six and one fourth inches long. All these birds of America are dull-colored, but some of the true Tits of the Old World are among the brightest birds of the northern hemisphere. For example, the azure tit of Siberia is white and sky-blue; the blue tit of Europe blue, white and yellow.
