Forster's Tern immature

A different nearly one-year-old bird showing the dark mask but with more dark on the nape. Some Forster's are darker than others on the nape and this alone does not indicate a Common. The blackish nape in Common is more contiguous with the auriculars, not separated into two patches as on this bird. The primaries and tertials are very dark similar to the previous individual, again a normal feature in a Forster's at this age. Note the large bill and lack of a covert bar.