The species breeds along northern coastlines (Gochfeld et al. 2014) and on inshore islands, as well as inland on tundra and forest-tundra (Flint et al. 1984). It shows a preference for habitats with a vegetation cover of less than 40%, nesting on sand or shingle beaches, ridges (Gochfeld et al. 2014) and spits, rocky ground and small islands (Flint et al. 1984) in lakes and coastal lagoons (Gochfeld et al. 2014). It may also nest on islets or banks along rivers (Snow and Perrins 1998), on swampy tundra and peatlands with bog hummocks (Gochfeld et al. 2014) and reed-covered flats (Flint et al. 1984), or on inland heaths, rough pastures, meadows (Gochfeld et al. 2014) and sedge grassland (Snow and Perrins 1998) not far from water (Flint et al. 1984). The species also forages offshore, in ice-filled coastal bays or over wet tundra (Gochfeld et al. 2014). On passage, it largely flies over open ocean (Snow and Perrins 1998) resting at sea on kelp, logs or flotsam, but may occur inland or along coastlines on beaches, reefs and spits (Higgins and Davies 1996).

The species breeds between May and July (although the exact timing varies with temperature and food availability) in solitary pairs or colonies of a few to several hundred pairs (usually 2–25). The nest is a shallow scrape (Gochfeld et al. 2014) in sand, shingle or turf (Richards 1990) on beaches, ridges and spits, rocky ground, small islands in lakes, coastal lagoons (Gochfeld et al. 2014) and rivers (Snow and Perrins 1998), swampy tundra and peatlands with bog hummocks (Gochfeld et al. 2014) and reed-covered flats (Flint et al. 1984), or on inland heaths, rough pastures, meadows (Gochfeld et al. 2014) and sedge grassland (Snow and Perrins 1998) not far from water (Flint et al. 1984). It will also nest on artificial structures. Clutches are two to three eggs.

Its diet consists predominantly of fish as well as crustaceans (especially planktonic species), molluscs, insects (e.g. caterpillars, Chironomidae) and earthworms. It will also take berries in the early spring on arrival on its breeding grounds but does not readily switch to other prey items when preferred prey supplies fail.

This species is a very strong migrant and makes exceptional long-distance movements offshore or along western continental coastlines (Melville and Shortridge 2006, Gochfeld et al. 2014) between its high Arctic breeding grounds and Antarctic wintering grounds (Gochfeld et al. 2014).

Although the generation length for both EU and Europe regional assessments were calculated using the same methodology, new information arriving after the EU assessments were undertaken gave rise to an update in the generation lengths. This new information was then used for the Europe level assessments giving rise to a difference between the generation lengths used for the EU and Europe regions.

In Europe, the species breeds primarily in Iceland, with significant numbers occurring also in Greenland, Finland, Romania, the United Kingdom, Sweden and Norway.

Conservation Actions Underway
CMS Appendix II. EU Birds Directive Annex I. Bern Convention Appendix II. In the Baltic Sea, removing feral American Mink (Neovison vison) from a large archipelago with many small islands resulted in an increase in the breeding density of this species in the area (Nordstrom et al. 2003).

Conservation Actions Proposed
Gull control measures may also be practised successfully at some sites to reduce predation and displacement, especially when carried out in conjunction with the use of recordings and models to induce recolonisation of nesting terns (Buckley and Buckley 1984). This species also benefits from the removal of American Mink (Nordstrom et al. 2003).