The American goldfinches that we see at our feeders right now (August) are in their breeding plumage. However, as we all know, the American goldfinches that visit our backyards in the winter appear to be totally different birds. This is because after the close of the breeding season the birds undergo a feather molt. As a result, a dull and somber winter plumage replaces their bright and beautiful breeding plumage. However, it is not commonly known that the color of the goldfinches bill, feet and legs change along with the feather molt.
At this time of the year, they are pale yellow. However, outside of the breeding season they are grayish brown. This change can best be appreciated if you compare the color of the feet, legs and bills of the American goldfinches you are currently seeing, with those of the bird in the photo (taken in winter) that accompanies this blog. The difference is truly remarkable.