Nuthatch Bird is a stocky, short-tailed and 'spear-headed' bird, usually seen climbing on tree trunks and branches and often coming downwards, headfirst. The bill is long and deep like a small chisel, and the upperparts are plain blue-grey with a strong black line through the eye from bill to nape. The throat of Nuthatch Bird is whitish and the remainder of the underparts are rufous-buff, darker and more intensely coloured on the flanks, with a rich red-brown vent that is boldly spotted with white. Females are less intensely coloured below. Birds of the nominate Scandinavian race are white on the belly.
Nuthatch Bird is a woodland bird found in deciduous and mixed forest, favouring mature trees and particularly very old gnarled and decaying ones offering nooks and crannies for feeding and cavities for nesting. Nuthatch Bird is also found in parks and large gardens, mature hedgerows and smaller wooded areas, as long as the trees are not too widely spaced. In the far north of its range it will nest in pure coniferous forest. It uses an existing hole for nesting, often plastering the entrance with mud to customize the diameter of the hole.
Nuthatch Bird is very vocal, with a wide variety of rather loud and far-carrying vocalizations that function as territorial, advertising and contact calls. Commonly heard is an excited single or slightly disyllabic "tyupp", "tu'iip" or "twehp", frequently repeated and often in rapid couplets such as "twehp'twehp, twehp'twehp, twehp'twehp". Nuthatch Bird also gives a flatter, quick "chud'ud'ud" and a longer "chtd'chtd'chtd'chtd'chtd'chtd" or "thk'thk'thk'thk'thk". It gives a conversational "sit" contact note when feeding generally, and a shivering, silvery "fsr'r'r'r'r'r'r". The song is variable, usually a loud clear piping whistle, repeated either slowly as "viou' viou' viou' viou' viou'..." or "pwee' pwee' pwee' pwee' pwee...", or rapidly as a liquid trilling "pi'pi'pi'pi'pi'..." or "pr'r'r'r'r'r'r...", as well as a nasal "ve've've've've've've".