Terns are small, gull-like birds, usually with a forked tail. Adult Roseate Terns are white or very pale grey with a darker, pearly grey mantle (back and upper side of the wings). A black cap extends down to the nape of the neck. The bill is also black, the forked tail is white, and the feet are a bright red-orange. Young Roseate Terns resemble the adults, but the feathers of the upperparts are tipped with black and buff, and the legs are black.
The Roseate Tern breeds locally on coasts and islands on both sides of the Atlantic Ocean, and winters along the northern coast of South America, from northeastern Guyana to Brazil. In Canada, the Roseate Tern is at the northern limit of its range. It breeds along the Atlantic coast in Nova Scotia and in Quebec, and has been seen in New Brunswick and in Newfoundland.
Roseate Terns usually begin breeding at three years of age. They nest in colonies, often with other species. They nest on the ground, sometimes lining the site with vegetal matter prior to egg-laying. Clutches usually contain two or three eggs.
During breeding, the male Roseate Tern flies in high circles, carrying a fish, followed closely by one or more females. The male and lead female descend together in a zig-zag glide as part of an elaborate courtship ritual.
The parents take turns incubating the eggs for 23-24 days. At hatching, the young are downy, have open eyes, and are able to walk but stay in the nest. Because of limited food availability, having two chicks survive to fledging is not typical. Chicks generally fledge when 25-28 days old, leave the colony, but stay with their parents for at least six more weeks while learning to fish on their own.
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The Roseate Tern eats small fish and some invertebrates. In salt water, they eat sand lance, white hake, juvenile herring, mackerel, gadid, cod, pollock, and haddock.
The Roseate Tern plunges into water from flight and can even “fly” short distances under water. They prefer to fish in rips, where currents meet, and other turbulent waters. They will steal fish from other terns, but gulls, crows and ravens may also steal fish from them.
A century ago, Roseate Terns were a favourite target of both hunters selling feathers to the millinery industry and egg collectors. Currently, human exploitation (trapping for market) of the Roseate Tern on its wintering grounds is the main limiting factor for the species. Predation at breeding colonies by gulls, crows, Northern Harriers, Short-eared Owls and other wildlife poses a constant threat, and seems to be the main reason for the selection of islands and islets as nesting sites. Competition from other species, such as larger gulls, for nest sites is another important limiting factor. Toxic chemicals passed through the food chain and their effects on reproduction (thinning of eggshells, premature breakage of eggs, and reduced reproductive success) are also a concern. A shortage of males may limit the productivity of Roseates at some colonies in northeastern North America, where 20% of breeding females do not obtain male mates.
The Roseate Tern is listed as “threatened” by the Canadian Wildlife Service. The northeastern population in the United States is “endangered,” the Caribbean population is also “threatened,” and the global status is “near threatened.”
Only 3% of the population breeds in Canada (the northern limit of the breeding range) and is estimated at fewer than 140 pairs, concentrated on a few islands off the Atlantic Coast of Nova Scotia.
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The largest Roseate Tern colonies in Canada are on Country Island (40 pairs in 2004) and the Brothers Islands (76 pairs in 2004). With so few nesting colonies, and with their vulnerability to predators such as mink, Roseate Terns require continued conservation management. In order to help recover Roseate Terns in Canada, efforts are underway to establish a third major nesting colony.
Nature Canada has identified three IBAs – two in Nova Scotia and one in New Brunswick – with the intention of securing protected nesting sites for the Roseate Tern. Since predation is the biggest concern, intervention is likely the only option. This process will require funding and ongoing local volunteer support.
Thank you to Colleen Sutton for contributing to this species profile.