Maybe they were driven here by the northwest wind. Or more likely the suet — a high-calorie treat to fuel their winter rambles. I hope they checked out the real estate while they were here: there are a couple of dandy bluebird houses in the neighborhood, and this time of year they're open for takers.
Mostly I wondered where they had come from and where they were going. I'd like to think they were the proverbial bluebirds of happiness, come to pay us a visit on this cold midwinter day.