Here is a male American Goldfinch. They are brilliant in their yellow plumage and they look like this all summer. However, at the end of summer they lose their black cap and the bright yellow feathers and they look very much like the females. This happens before they leave in the fall. Goldfinches don’t start nesting until about July. Many birds feed their babies insects, but the Goldfinches feed their babies seeds. By delaying their nesting, they time it so there are lots of thistle seeds (one of their favorites) available.