The American goldfinch is the smallest bird that comes to our feeders. Sunflower seeds are too big for them. They like thistle seeds which they eat upside down from a special feeder designed to prevent raids by sparrows and larger birds.
Goldfinches are found throughout the U.S. and southern Canada. The Canadian goldfinches head south in winter. They are found year round in the central United States.
They inhabit weedy fields, woodland edges and open habitats with scattered shrubs. In the winter goldfinches roam in noisy flocks, seeding food in fields, gardens and feeding stations.
Goldfinches are seedeaters in all seasons, consuming a variety of weed, grass and plant seeds and tree buds.
See: "Michigan Bird Watching, A Year-Round Guide" by Bill Thompson III and the staff of Bird Watchers Digest.