The Common Tern, Sterna hirundo, is a slender seabird with a circumpolar distribution, breeding in temperate and subarctic regions of Europe, Asia, and North America. It is a migratory species, wintering in coastal tropical and subtropical regions. Adults display light grey upperparts, white to very light grey underparts, and a black cap. Their legs are orange-red, and they possess a narrow pointed bill, which varies in color between subspecies.
To identify the Common Tern, look for its pale grey upper wings, which develop a dark feather shaft as the season progresses, creating a grey wedge. The rump and tail are white, and the tail extends no further than the folded wingtips when the bird is standing. The bill is mostly red with a black tip or entirely black, depending on the subspecies. In non-breeding adults, the forehead and underparts become white, and the bill turns black.
Common Terns are found nesting on flat, poorly vegetated surfaces close to water, such as beaches, islands, and artificial substrates like floating rafts. They adapt to a variety of habitats, from the taiga to tropical shores, and avoid excessively rainy, windy, or icy areas.
This species has a wide breeding range, encompassing Europe, North Africa, Asia, and North America. It migrates to winter along the coasts of Central and South America, Africa, and southern Asia, with some populations remaining partially migratory in the Caribbean.