It is only the adult males that show color. So, in a flock of red finches only a few of the birds will show a red head. There are more than one kind of red headed finch. In fact, in the United States ...

Adults have characteristic red cap or “poll.” Polytypic. Length 5.3". The common is generally a relatively small, streaked finch with a small, pointed bill; short, deeply notched tail ...