The American goldfinch (Spinus tristis) is a migratory bird that lives from Canada to the mid-South in the summer and from the northern U.S. to Mexico in the winter. One of 140 species of the finch subfamily, the goldfinch is a tiny creature, only four to five inches (11-13 cm) in length and 0.4 to 0.7 ounces (11-20 grams) in weight.
The goldfinch is unique in that it molts or loses its feathers twice a year. In the late summer, males molt from a vibrant yellow and shiny black to olive. In late winter, the males signal the coming of spring by molting back to yellow. The female goldfinch is a drabber color and only brightens slightly in the summer. These social creatures―they are only territorial while building their nests―gather in large groups to feed and migrate.
Unlike many other species, goldfinches have benefited from the clearing of forests. They are vegetarians that mostly eat seeds, so opening up large areas of land has made it easier for them to find food.