Someone sent me a photo today of a Sharp-shinned Hawk and asked the age of it. This prompted me to post the photo comparison above (click to enlarge). I show this in my hawk guides, but thought it would be easy to post here. It is interesting how some adult (left) and juvenile (right) birds can appear similar in plumage. Sometimes heavily marked juveniles with blobby, rufous streaking on the underbody can look adult-like. But you can see the real difference between the adult barring compared to the markings of adult-like juveniles. The underwing pattern is basically identical on both ages, but the cheeks and head differ. Note the dark under the eye of the adult and if the head was turned a bit, you would see the dark cap.

Anyway, the difference in plumage is obvious from this composite, but sometimes difficult to tell in the field. Also, the juvenile pictured is in complete juvenile plumage, it has not molted one feather yet. Most people assume a juvenile bird (especially after April when some do start to molt into adult plumage) that looks adult-like must be in a transition stage of molt, but that is not the case here, and not the case most times when people have sent me photos to assess.