Bushtits are tiny, kinglet-sized birds. They are plump and large-headed, with long tails and short, stubby bills. Bushtits are fairly plain brown-and-gray birds. Slightly darker above than below, they have brown-gray heads, gray wings, and tan-gray underparts. Males in parts of the range have contrasting blackish face masks.

https://www.allaboutbirds.org/guide/Bushtit/id