Brown creepers are cute little bits of camouflage with white bellies. This one moved upward in staccato motions, a bit to the side, around to the back, back to the front, and up some more. Pausing, the bird used their thin, downward-curving bill to explore a bark furrow. Perhaps they had spotted an overwintering insect larvae or antifreeze-protected spider for their lunch. Near the limit of my view out the window, the creeper suddenly launched off the tree and fluttered downward toward another tree trunk, out of sight.