The chestnut-backed chickadee is curious about humans, and spends the postbreeding and winter seasons foraging noisily in mixed-species flocks. Unlike other parids (except for the mountain chickadee), it forages high in the canopies of tall conifers. This species is the smallest chickadee in North America. One of the 3 “brown-backed” species (along with boreal and gray-headed), its nominate subspecies is the most richly colored parid. Polytypic. Length 4.8".

The chestnut color of the back is unique, but it varies in intensity. The cap is dark brown, shading to black at its lower edge from the bill through the eye; the cheek is white; the bib is black; the back and rump are rufous; the greater wing coverts are edged white;