In the Summer, the male Goldfinch is a bright yellow and black bird. In the Winter, the yellow is replaced by an olive green color. The female and juveniles are similar in coloring to the male's Winter coloring. They are 4.5 to 6 inches long and can be found throughout most of the United States. They are particularly fond of thistle seeds. Several years ago, I purchased a "small bird" feeder and filled it with thistle seeds. Although I hadn't seen any Goldfinches near our home, they found the feeder about 20 minutes after I put it up.