This species lives in shallow inlets, at coasts and in lakes. It is capable of exploiting a variety of connected habitats, e.g. shifting from salt water to fresh water when fishing. It feeds on small fish, shrimps and large freshwater insects. Breeding sites are mostly placed on predator-free islands or islets with no or sparse, short vegetation. Breeding colonies are mostly 20 pairs or less, but breeding in solitary pairs also occurs.
The common tern is listed on Annex I of the Birds Directive (Directive 2009/147/EC).