American Goldfinches are the only finch that molts its body feathers twice a year, once in late winter and again in late summer. The brightening yellow of male goldfinches each spring is one welcome mark of approaching warm months.
American Goldfinches breed later than most North American birds. They wait to nest until June or July when milkweed, thistle, and other plants have produced their fibrous seeds, which goldfinches incorporate into their nests and also feed their young.
Goldfinches are among the strictest vegetarians in the bird world, selecting an entirely vegetable diet and only inadvertently swallowing an occasional insect.