The family Sittidae includes 4 species found in North America.

Nuthatches forage on the trunks and branches of trees or the faces of rocks and cliffs. The nuthatches and Wallcreeper do not brace the tail against the substrate when climbing about on trees or rocks. They often descend down tree trunks headfirst. They have long, curved, sharp toenails, short tails and sharp, straight beaks.

They are 13-20 cm. in size. Plumage is usually gray or bluish-gray above, white below, some with rufous underparts, some with a black or brown crown. 

Food is insects and seeds. Some open nuts with their sharp bill. They nest in a crevice or tree hole, lined with grass, moss, hair. Old World species reduce the size of the entrance hole with mud. They lay 4-10 eggs, white with reddish spots. The female incubates 12-14 days. Young are fed by the male.