I'm so glad I got to observe American Goldfinches in winter or non-breeding plumage since I had no idea that they changed this much. While the other species in its family molt once in the fall, American Goldfinches through a second molt in the spring.
I've been observing their daily change in color. At this point, they're almost all yellow.
And how ironic that these pictures are of my black oil sunflower seed feeder...But I stand by my argument that the thistle feeder is what drew them to my yard!
I just found some older pictures (taken February 1st) that I never posted. This picture shows the drab winter plumage of the goldfinch.