Bird Identification: CLOSED: Bushtits (?) In December, 4 by wingwoman

wingwoman wrote:
I often see Bushtits in the summer, and have spent many hours searching among our lilacs looking for their unusual nest. Yesterday, I spied motion through our dining room window, and saw these guys (crappy focus). Seriously? Bushtits in Denver at 8 degrees above zero? Which begs the question regarding migration, like were they just passing through and taking a break in some kind of Bushtit pilgrimage to someplace. They clustered, and then were gone. Very curious about this one, and thanks for any help.