The roseate tern (Sterna dougallii ) is a tern in the family Laridae. The genus name Sterna is derived from Old English "stearn", "tern", and the specific dougallii refers to Scottish physician and collector Dr Peter McDougall (1777–1814). "Roseate" refers to the bird's pink breast in breeding plumage.
The Roseate tern has a similar size to the common tern but it is very white-looking, and has long tail-streamers, and its head is black with a black beak on a reddish base. During summer the underparts of adults have a pinkish tinge, which gives this bird its name. Roseate terns have a very buoyant and light and flight, with relatively shallow and fast wingbeats. They often make a musical call when flying. It is primarily a tropical species and breeds around the globe in tropical seas. Its lifespan is 8 years on average and the oldest individual on record was 25.8 years old.
Roseate terns are found mainly in the northern hemisphere on North America’s northeastern coast, from Nova Scotia to Florida’s southernmost tip, as well as a number of islands in the Caribbean Sea, also northwestern Europe, west and south Africa, and Western Australia. These birds nest on rocky or sandy islands that offer some low plant cover, near to shallow waters where they can feed, especially in protected estuaries and bays. They tend to forage in coastal waters but also sometimes well offshore, seeming to prefer warmer waters.
After hovering, Roseate terns will plunge-dive to take fish from the surface of the water, often fully submerging. These birds are diurnal. They feed either alone or in a small flock, and tend to dive from greater heights than do other terns, as far as 20 m from the surface of the sea. They like to forage over substrates that are sandy, making use of shallow waters and areas where there is upwelling, including shoals and tidal rips. The range of foraging varies between colonies and according to the season, with a maximum of 30 km foraging distance recorded. This species is a long-distance migrant. In winter in late August until early September, it migrates south, from the U.S. in the northeast to waters off Trinidad and the north of South America, and from Columbia’s Pacific Coast to eastern Brazil. Populations of European roseates usually migrate to southern and western Africa. A somewhat vocal species when on the breeding grounds, the calls of the Roseate tern include a 'chew-ik' sound and a 'kraak' when it is alarmed.
Roseate terns are carnivores (piscivores), they mainly eat small fish, including many herring and sand lance; also some crustaceans, and mollusks, but rarely insects.
The Roseate tern is a monogamous, colonially nesting seabird, which forms a long-lasting pair bond. These birds nest together on small barrier islands, frequently at ends or breaks. The nest is in a hollow or under thick vegetation, rocks or debris, hidden from predators. These terns in the northeast of North America almost invariably nest in colonies alongside common terns. Towards the end of April Roseate terns start arriving at breeding areas, and begin to lay eggs in the third or fourth week in May. Early in the breeding season, groups fly high and glide down together. On the ground, the birds display with their tail raised and neck arched, and the male may feed the female. One to two eggs are laid, rarely three. They rely on the Arctic and Common terns in the colony around them to defend them, as these birds are more aggressive. Incubation is done by both parents (though the female may do more) for 21-26 days. The young are fed by both their parents and they may move away from the nest for better shelter several days after hatching. Their first flight is usually at the age of 27-30 days, but they remain with their parents for at least 2 months more. Roseate terns usually don’t breed until they are 3 years old.
These birds were hunted in the late 19th century for their feathers which were used in hat decoration. More recently, in some regions their numbers have decreased due to more competition and predation by big gulls, whose numbers have grown in recent times. This species is also threatened by predation by foxes, peregrines and brown rats. Human egg collecting and disturbance may have also affected them, though this has largely been stopped in the UK by warden schemes. Threats to the Roseate tern in its wintering range or while it is migrating, are trapping and reduction in roost sites.
The IUCN Red List puts the total Roseate tern population at around 70,000-82,000 individuals. National population estimates are: in China: 100-10,000 breeding pairs, with 50-1,000 individuals on migration; in Taiwan: 100-100,000 breeding pairs and 50-10,000 birds on migration, and in Japan: 100-10,000 breeding pairs and 50-1,000 birds on migration. Currently Roseate terns are classified as Least Concern (LC).