Forster's Tern

Forster's Tern exhibit notable courtship rituals, such as synchronous high flights, slow wingbeats, and coordinated descending maneuvers, often with the male presenting a fish. These displays also occur with aerial hoverings and ground parades within their colonies. Their courtship includes a unique 'courtship feeding' where males offer fish to females. Forster's Tern share both incubation responsibilities and territorial defense of their small nests. They engage in a range of defensive behaviors, from vocalizations to physical confrontations. Post-fledging, forster's Tern families may migrate together. In nonbreeding seasons, they're gregarious, foraging and roosting in groups on coastal substrates.

Forster's tern is a marsh dwelling species. It can be found either in freshwater, brackish or saltwater. It is often found over shallow open water deep in the marsh. Main habitats are marshes, estuaries, islands, salt marshes and marshy areas surrounding lakes and streams. Forster's tern is usually restricted to North America. It nests in marshes during the summer, either on the Atlantic or Pacific coast, but also in the Prairies or along the Great Lakes in Canada and the US. Due to the instability of its nesting habitat, Forster's tern exhibits a high annual turnover rate. 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. It is also common for the tern to winter in the Caribbean. It can annually visit Western Europe and has occasionally wintered in Great Britain and Ireland.

According to the IUCN, the status of the Forster's tern is of little concern, however, degradation of marsh habitat may be threatening. Boating activity may also affect nest vegetation and increase erosion, which may lead to further degradation of tern nesting grounds. Excessive noise may also have caused nest desertion and chick mortality. This species is listed under the Migratory Birds Treaty act in the U.S. It is endangered in Illinois and Wisconsin while being of special concern in Michigan and Minnesota. Preservation of wetlands and introduction of artificial nesting sites may help preserve the species in high-risk areas (). Increasing populations of carp in drainage systems, causing damages 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. As with many species of piscivorous birds, Forster's tern is susceptible to bioaccumulation of pollutants. High mercury concentration may induce biochemical stress, reducing the overall health of terns. Biomethylation of mercury is increased in marshes and salt ponds, hence increasing the susceptibility of the Forster's tern. High levels of Selenium may also have deleterious effects on their health. Organochlorine contaminants such as PCB may also diminish their breeding success.