Chestnut-backed Chickadees are very active and acrobatic, clinging to small limbs and twigs or hanging upside-down from cones. In winter, they flock with kinglets and nuthatches. Flight is generally short and undulating, with flock members setting out to cross openings one at a time.
They are found in dense coniferous and mixed coniferous forests of the Pacific Coast and prefer not to feed on the ground. You can also find them in shrubs, trees, and parks of cities, towns, and suburbs.
I never have seen one, a nice colorful version of our black capped out east here. The heads are almost identical, but the brown back certainly separates them with those warm tones, our black capped are black and white only.