Sandwich Tern bird is larger and bulkier than the other terns in our region, with long narrow wings and a whiter overall appearance. Sandwich Tern bird has a rather long and large head, and the bill is long and black with a pale yellow tip. It has a black cap and shaggy crest, black legs, and the upperparts are pale grey - often looking very pale at range - with a weakly defined dusky wedge on the wingtip. It has a front-heavy appearance, exaggerated by the large head and shorter tail, and when fishing dives from a reasonable height to catch its prey.
Sandwich tern bird is a summer visitor favouring coastal regions, where it nests on inshore sandy islands, rocky islets, sand spits, dunes, undisturbed shingle beaches, shallow bays, deltas and other dry, sandy sites in saline and brackish environments, with adjacent feeding areas in shallow, sandy-bottomed waters rich in surface-level fish. Sandwich tern bird migrates along the Atlantic coasts and is very rare inland, although some nest locally on islands in freshwater lakes close to the coast. Migrates to warmer waters off Africa for the winter.
Sandwich Tern bird is noisy and vocal, especially in the breeding season and around nest colonies, but also when out fishing and foraging or travelling with dependent juveniles in tow. The typical familiar call is a loud grating, almost disyllabic "ear'rink!" or "ar'rrenkl", delivered on a true level tone, or with the second half descending and lower in pitch. Sandwich Tern bird is often described as "kerrick" or "kirrink" and is audible from some distance. The species has a limited variety of other calls, all of them harsh, such as a dry chattering "ih'ih'ih'ih", a short sharp "ik'ik", and some short growling "aekh! aekh!" notes, as well as a vowel-less growling "krr'rrrgh". They also give a higher-pitched trilling "srrreee" or "rrrrr'i'i'i'i", and juveniles are vocal when following adults, giving a high plaintive "psee-psee".