The genus name Sterna is derived from Old English "stearn", "tern",[2] and forsteri commemorates the naturalist Johann Reinhold Forster.

It is also a rare but annual vagrant in western Europe, and has wintered in Ireland and Great Britain on a number of occasions.

The Forster's tern feeds by plunge-diving for fish, but will also hawk for insects in its breeding marshes.

This species is unlikely to be confused with the common tern in winter because of the black eye mask, but is much more similar in breeding plumage.

Forster's has a gray center to its white tail, and the upperwings are whiter, without the darker primary wedge of the common tern.

[5][6] In its non-breeding plumage, the crown is white and a black comma-shaped patch covers the eye and the ear-covert.

[5] Its closest relative is the snowy-crowned tern (S. trudeaui) of South America; the two are sister species and basal to the rest of the genus Sterna.

[6] It nests in marshes during the summer, on both the Atlantic and Pacific coast, and also in the Prairies and on the Great Lakes in Canada and the US.

[5][6][9] Due to the instability of its nesting habitat, Forster's tern exhibits a high annual turnover rate.

[9] Forster's tern also winters in marshes along the southern coast of the US and Mexico but can sometimes reach the northern extremity of Central America.

[12] Both parents are involved in brood care and Forster's tern does not exhibit sex-specific differences in space use.

[11][17] On the West Coast of the United States and Canada, Forster's tern is also known to prey on Pacific lamprey juveniles.

[5][10] The attack usually starts in a hovering position before initiating a headfirst dive with wings partially folded backward.

[20] The breeding season for Forster's tern can start as early as April on the Gulf Coast of the United States and extend from May to mid-June depending on latitude.

[22] The chicks usually leave the nest with the parents four days post hatching and move into areas of denser vegetation.

[21] After a few weeks of fledging, young terns leave the natal colony but join the group for roosting, while migrating towards the wintering ground.

[12] Western grebes recognize the tern's alarm call; this can be interpreted as information parasitism.

[11] The nests will consist of a hollow in the substrates, either lined with grass or not and driftwood, shells, dried fish, bones and feathers are also often used.

[21] Floating nests are usually tolerant to a slight increase or decrease of water levels but re-nesting is common.

[11] Strong wave action, wind or flooding, usually induced by storms, can often damage the nest and eggs.

[11][12] Forster's Terns have been recorded using man-made platforms, most notably in Wisconsin, where they were built to substitute for the Cat Island Chain.

[11] When their ranges overlap, marsh rice rats are possibly the most efficient Forster's tern egg predator.

[12] Predator success usually remains low during breeding season due to the aggressive mobbing response of adults.

Increasing populations of carp in drainage systems, causing damage to marsh vegetation, may limit habitat availability for Forster's tern.

There have also been anecdotal reports of intense spawning activity of carp damaging tern's floating nests.