Common Tern

Voice

Piercing and sharp. The contact call is a downslurred kreee-arr, accelerating when agitated into a rattling kik-kik-kik over the colony. Heard from late April into August; largely silent at sea outside the breeding season.

Identification

Slender, with long narrow wings and a deeply forked tail whose streamers just reach the wingtip at rest. Summer adult: black cap, orange-red bill with a black tip, short red legs, pale grey body. In flight a dark wedge shows on the outer primaries above, and from below only the inner primaries are translucent.

Confusion species

Arctic Tern: blood-red bill without a black tip, strikingly short legs, longer streamers, and an evenly translucent hand below with a neat narrow dark trailing edge. Sandwich Tern is bigger and paler with a yellow-tipped black bill and shaggy crest. Little Tern is far smaller with a white forehead and yellow bill.

Habitat

Shallow clear water beside a safe, bare nesting site: shell banks, saltmarsh edges and islets in coastal lagoons, but equally rafts and gravel islands in flooded pits and industrial waters.

Range and movements

Breeds across Europe from the Baltic coast to Iberia. The Netherlands is a stronghold, with colonies in the Delta, the Wadden Sea and around the IJsselmeer, often on purpose-built islands. In Spain mainly the Ebro Delta and the Guadalquivir marshes; all birds move to West Africa.

• Breeding (summer)
• Winter
• Passage
• Migration direction
• dark = core range, pale = thinly spread

Where and when to look

May and June at a colony, watched from a dyke or hide at a respectful distance. Concentrate on birds arriving with a fish: bill colour, leg length and tail streamers all show in one view. Coastal passage peaks in August.

Conservation status

Numerous but fragile, because the species depends entirely on managed nesting islands. Storm flooding, predation by foxes and gulls, disturbance on beaches, and the availability of small fish close to the colony decide breeding success from year to year.