While staying with friends at a rented house in Southern Vermont a few weeks ago, we were visited a few times a day by a feeding "gallup" or flock, of Common Redpolls.
These hardy little finches thrive in colder weather, and they mostly live in the Northern parts of North America. Every other year, depending on the food sources in Winter, they will move south (irruption) to Northern New England and New York to find food.
From the Wikipedia page on Bird Migration:
"Sometimes circumstances such as a good breeding season followed by a food source failure the following year lead to irruptions in which large numbers of a species move far beyond the normal range. Bohemian Waxwing and Common Crossbills show this unpredictable variation in annual numbers."
This image is now included in my Getty Images stock library.