© Copyright: Images: Jari Peltomäki, Mervi Wahlroos, M. & W. von Wright: Svenska fåglar (Kansalliskirjasto, The National Library of Finland). Recording: Jan-Erik Bruun. All rights reserved.
- Latin synonym: Sterna caspia
- Family: Terns – Sternidae
- Appearance: Finland’s largest tern. Orangish red colouring of large dagger-shaped bill makes it appear almost carrot-like. Extensive dark colouring on wingtips. Black or dark cap prominent on birds in all plumages.
- Size: Length 48–55 cm, wingspan 125–140 cm, weight 570–780 g.
- Nest: Made in a shallow depression on the highest part of a small island in a hollow in the rock or on sand or gravel. Nest material usually limited, mainly grass stalks and fish bones from regurgitated pellets.
- Breeding: 2–3 eggs laid in May, incubated by both parents for 25 days. Young able to fly within approximately 36 days.
- Occurrence: Breeds on outer islands in Finland’s Baltic archipelagoes, individually or in colonies. Can be seen along coasts and by lakes during migration. Finnish breeding population estimated at 800–900 pairs. Species classified as vulnerable in Finland.
- Migration: Flies south towards tropical Africa in July–August (occasionally as late as September), returning between mid April and late May.
- Diet: Dives into the water to catch medium-sized or small fish.
- Calls: Most commonly a harsh squawk.
- Endangerment: Least concern, protected throughout Finland including the Åland Islands.
Caspian Terns are large terns, about as large as Black-headed Gulls, with long narrow wings that are pale bluish grey above and white below, with extensive black colouring on the wingtips. Their tails are slightly forked. They have black caps and large, bright red dagger-like bills. Juveniles mainly resemble adults but their caps are dark brown with white flecks, and they also have brown flecks on their backs and tails. Caspian Terns’ legs are black (adults) or greyish yellow (juveniles), and their irises are dark brown. Adults’ bills are orangish red with a black tip, but juveniles’ bills are a duller reddish colour with a yellow tip.
Caspian Terns fly evenly and strongly, with their wings angled back. When fishing, they fly at an altitude of about ten metres with their bills pointing downwards, before hovering briefly on seeing a fish, and then plummeting down into the water with an audible splash. After first catching a fish and starting to fly off they may drop it and catch it again in mid-air aligned in the optimal position for carrying.