© Copyright: Images: Jari Peltomäki, Jouko Lehmuskallio, M. & W. von Wright: Svenska fåglar (Kansalliskirjasto, The National Library of Finland). Recording: Jan-Erik Bruun. All rights reserved.
- Family: Terns – Sternidae
- Appearance: A smallish tern, very similar to Arctic Tern, but bill fairly long, legs, head and neck longer, and wings slightly wider. Adults have black tips on their otherwise red beaks. Flight more stable than Arctic Tern.
- Size: Length 34–37 cm, wingspan 70–80 cm, weight 100–145 g.
- Nest: Shallow nest built on bare ground, on a seaweed bank or in low grass. Nest material varies between individuals, but may include straw, twigs, seaweed, pine and spruce needles etc.
- Breeding: 1–3 eggs laid in May, incubated by both parents for 20–23 days. Fledglings learn to fly within 24–30 days.
- Distribution: Breeds on islands and shores of inland lakes and the inner archipelago zone around the coast. Finnish population estimated at 50,000–70,000 pairs.
- Migration: May migrate by day or night. Flies south in July–August (a few birds only migrate later), returning mainly in May. Winters in Southern Africa, but birds ringed in Finland have also been found as far away as Australia.
- Diet: Mainly small fish. Dives into water from hovering flight to catch prey.
- Calls: “Kit, kit” and a “tii-raa” cry.
Adult Common Terns have white underparts and pale grey back and wings. They have conspicuous black caps, and some darker colouring on the trailing edge of the tips of their primary wing feathers. They closely resemble Arctic Terns, but can be distinguished by the black tip to their beak, their longer legs, broader and only slightly transparent wings, and more stable flight. Their white tails are deeply forked.
Juvenile Common Terns have slightly darker grey backs (with some brown and white edges to their feathers) and darker colouring visible on the leading edge of their secondary wing feathers. Their foreheads are mainly white and their black caps only begin behind their eyes. Common Terns’ legs are red (adults) or orange (juveniles), their beaks are red with a black tip (adults) or dark brown with a yellowish base (juveniles), and their irises are dark.