The bird above is an immature female. She still carries rows of spots on her throat that fade to invisibility as the bird matures. The bird pictured below is a mature female. She lacks the red throat or "gorget" of the mature male and no longer has her juvenile spots on the throat either. The difference between females and young males is only apparent when you compare the tails of the two. Sometimes it is difficult to do so in the field. If you have not already seen them, pictures clearly showing this difference can be found by comparing the images at this link.