Often seen clambering up or headfirst down trees, this small active bird is usually found in the middle levels of the forest, though it will descend down toward the ground on occasion. Gray above and warmly-colored below throughout its range; eastern birds are paler below than western birds, the males of which have dark rusty bellies. Western birds also sport a bright contrasting white moustache. Lack of bright white patch on the tail distinguishes this species from White-tailed Nuthatch. A species of hill and submontane forests, where it favors lightly wooded areas of both broadleaf deciduous and pine forests. Often detected by its quick, echoing trill.