Nuthatches are diminutive, mainly arboreal birds, most of which dwell in the Northern Hemisphere. The species is thought to have originated in southern Asia, and 15 species are known to exist in the mountainous regions of central and southern Asia. 12 of these species are ecologically isolated from one another.
Nuthatches are plump, short-tailed birds with robust bills. These are generally elongated, but can be curved as well. They are known for their short legs, long toes and strong claws which are adapted for climbing. Most species possess great agility in climbing on tree trunks, moving upwards, sideways, or downwards, head-first, hoping to find stored seeds missed by other birds but easily see from a face-down perspective.
Nuthatches are solidly build; their heads are large, their legs short, their wings tight and their beaks and feet strong. Twelve square, short tail feathers fan out from their bodies.
In plumage, the Nuthatches display variations on the normal blue-gray upperparts and black eye stripes. Their head patterns are also variations on the black, white and blue-grey. Their underparts vary from white or buff to rufous. Some species have rufous on their whole underside surface; others have rufous markings only in small areas, such as on the breast band. Some of the Asian species’ upperparts are violet-blue instead, and some have red or yellow bills. Often their white underparts are brushed with various shades of buff, orange, rufous or lilac. Head markings are similar between the species: All have some form of black eye stripe, white supercilium, and black crown.
Males and females appear similar, although there may be some differences in the colors of their rear underparts. Immature birds show nearly identical markings to the adults.
Nuthatches vary in size. They vary in size from 3.75 inches up to 7.75 inches (195 mm) in length.