11 cm (4-5") Common. Southwestern United States. Desert mesquite, thorny shrubs.
Small active bird with a small bill. Gray body. A chestnut shoulder patch but may not always be seen. Yellow head and throat.
Immature: lack yellow head and throat and shoulder chestnut patch; they are grayish-brown overall and have a shorter tail than similar Bushtit.
Song: whistled "tsee, seesee", call is a rapid series of chips.