Forster's Tern alternate

This individual is almost fully in alternate plumage, with only a few flecks of white on the forecrown and a bit darker bill than seen later in the season. The size of the bill and leg length are helpful separating from Common, but best used in direct comparison. Much more helpful in this view is the appearance of the wingtip, showing the extensive pale coloration typical of Forster's. Note the pale outer tail feathers, too. Common Tern in alternate plumage often is grayer below as well. The primaries on this bird extend beyond the tail, which can be seen with both species.