© Copyright: Images: Jari Peltomäki, Jouko Lehmuskallio, M. & W. von Wright (Kansalliskirjasto, The National Library of Finland). Recording: Jan-Erik Bruun. All rights reserved.
- Family: Terns – Sternidae
- Appearance: A smallish tern, similar to Common Tern, but has slightly shorter beak, legs head and neck, and narrower wings. Mature birds have bright read beaks, only seldom with black colouring on the tip. Flight similar to Common Tern, but a little more graceful.
- Size: Length 33–39 cm, wingspan 66–77 cm, weight 95–125 g.
- Nest: A small hollow scarped out in sand or gravel.
- Breeding: 1–3 eggs laid in May, incubated by both parents for 22 days. Fledglings learn to fly within 24–30 days.
- Distribution: Breeds on outer islands of coastal archipelagoes and by lakes and marshy pools in Finnish Lapland. Finnish breeding population estimated at 60,000–90,000 pairs.
- Migration: Probably the world record holder for long distance migration. Some birds use westerly winds to fly as far south as Antarctica during the northern winter. Migrates by night and day. Flies south July–August (some birds later), mainly returning in May.
- Diet: Chiefly small fish, caught by hovering and then plunging into water to spear them.
- Calls: “Kyik, kyik” ja “tee-ree” cries.
Adult Arctic Terns have white underparts, pale grey upper parts and black caps. Adults appear very similar to Common Terns, but may be distinguished by their totally red beaks, their shorter legs, their narrower and largely transparent wings, and their more graceful flight. Their white tails are very deeply forked, and extend well behind their wingtips when birds are sitting.
Juveniles have grey backs (with white edges to their feathers) and the elbows of their wings have less extensive dark colouring than on young Common Terns. Their foreheads are mainly white and their black caps only begin above and behind their eyes. Arctic Terns’ legs are red (mature birds) or orange (juveniles). Adults’ beaks are red (only very seldom with some black colouring on the tip). Juveniles’ beaks are black with a reddish base. Their irises are dark.