do yellow finches change color in the winter
Yes, the male is a vibrant yellow in the summer and an olive color during the winter.
American goldfinch
 the male is a vibrant yellow in the summer and an olive color during the winter
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American goldfinch [SEP] Introduction
The American goldfinch ("Spinus tristis") is a small North American bird in the finch family. It is migratory, ranging from mid-Alberta to North Carolina during the breeding season, and from just south of the Canada–United States border to Mexico during the winter. The only finch in its subfamily to undergo a complete molt, the American goldfinch displays sexual dichromatism: the male is a vibrant yellow in the summer and an olive color during the winter, while the female is a dull yellow-brown shade which brightens only slightly during the summer. The male displays brightly colored plumage during the breeding season to attract a mate.