ID tips & tricks

Long, black-tipped bill Longer neck, wings look set back Long wings, short tail Dark wing wedges Many birdwatchers are ‘brought up’ with the idea that Common and Arctic Terns are pretty much inseparable in the field. This state of affairs was propagated by earlier fieldguides, which often appeared to use a copy and paste approach to illustrating the two species. Some birdwatchers still confuse the two species, especially early in the spring, when there are plenty of Common Terns about and there is a sense of anticipation of the first Arctics. When a ‘real’ Arctic does arrive, the myth reveals itself. There enough distinguishing features of these two red-billed terns to make separating them reasonably straightforward, even at long range. Starting with structure, Common Terns are bigger, more robust looking birds. The bill and neck are substantially longer and the wings seemingly set further back on the body, and the tail is shorter. Relatively delicate Arctic Terns have short darker red bills, shorter necks and longer tails, making the wings look set further forward. The flight of Common Terns is more powerful on more flexible, flicky wing beats, while Arctics look light and graceful, often with the outer tail streamers appearing separate from the rest of the tail as they swoop in flight. In terms of pattern, Arctics are subtly paler birds, lacking dark smudging in the wings, with a translucent look to the flight feathers and very neat dark edges on the trailing edge of the primary feathers.