Roseate Tern
Encyclopedia
The Roseate Tern is a seabird
of the tern
family Sternidae. This bird
has a number of geographical races, differing mainly in bill colour and minor plumage details.
S. d. dougallii breeds on the Atlantic coasts of Europe
and North America
, and winters
south to the Caribbean
and west Africa
. Both the European and North American populations have been in long term decline, though active conservation measures have reversed the decline in the last few years at some colonies.
The tropical forms S. d. korustes and S. d. bangsi are resident breeders from east Africa across the Indian Ocean to Japan
. They have more red on the bill. The long-billed and short-winged S. d. gracilis breeds in Australia
and New Caledonia
. The northwestern Indian Ocean holds populations of S. d. arideensis. Some authors suggest that only three races arideensis, gracilis and nominate dougallii should be retained.
This species breeds in colonies on coasts and islands. It nests in a ground scrape, often in a hollow or under dense vegetation, and lays one or two (rarely three) eggs. It is less defensive of its nest and young than other white terns, often relying on Arctic
and Common Tern
s in the surrounding colony to defend them. In smaller colonies, they may rarely mate with these other tern species.
As with other Sterna terns, Roseate Tern feeds by plunge-diving for fish
, almost invariably from the sea; it is much more marine than allied terns, only rarely visiting freshwater lagoons on the coast to bathe and not fishing in fresh water. It usually dives directly, and not from the "stepped-hover" favoured by Arctic Tern
. The offering of fish by the male to the female is part of the courtship display.
Unusually for a tern, the Roseate Tern shows some kleptoparasitic behaviour, stealing fish
from other seabirds, at British colonies most often from Puffins
. This habit greatly increases their food collecting ability during bad weather when fish swim deeper, out of reach of plunge-diving terns, but still within reach of the deeper-diving Puffins.
This is a small-medium tern, 33–36 cm long with a 67–76 cm wingspan, which can be confused with the Common Tern
, Arctic Tern, and the larger, but similarly plumaged, Sandwich Tern.
Roseate Tern's thin sharp bill is black, with a red base which develops through the breeding season, and is more extensive in the tropical and southern hemisphere races. It is shorter-winged and has faster wing beats than Common or Arctic Tern. The upper wings are pale grey and its under parts white, and this tern looks very pale in flight, like a small Sandwich Tern, although the outermost primary flight feathers darken during the summer. The adults have very long, flexible tail streamers and orange-red legs. In summer, the underparts of adults take on the pinkish tinge which gives this bird its name.
The call of the Roseate Tern is a very characteristic chuwit, similar to that of the Spotted Redshank
, quite distinct from other terns. In winter, the forehead becomes white and the bill black. Juvenile Roseate Terns have a scaly appearance like juvenile Sandwich Terns, but a fuller black cap than that species.
In the late 19th century, these birds were hunted for their plumes which were used to decorate hats. More recently, their numbers have decreased in some regions due to increased competition and predation by large gull
s, whose numbers have increased in recent times.
With their favouring partly hidden nest sites, the provision of nestboxes has proven a dramatic conservation success, with the birds taking to them very readily. This results in greatly increased breeding productivity with the protection given to the young from predatory birds like Herring Gulls. At one colony on Coquet Island
, Northumberland
, the population rose from 25 pairs (1997) to 92 pairs (2005) after nestboxes were provided. Similar measures have been undertaken at the Anglesey tern colonies
along with clearance of vegetation, in particular Tree Mallow.
. One of the main reasons given in the UK plan for threat to the species is global warming
, creating an alteration of vertical profile distribution for its food source fishes. The Roseate Tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
) applies.
The Canadian Wildlife Service lists the Roseate Tern as Threatened. The U.S. Department of Interior lists the northeastern population as Endangered and the Caribbean population as Threatened.
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
of the tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...
family Sternidae. This bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
has a number of geographical races, differing mainly in bill colour and minor plumage details.
S. d. dougallii breeds on the Atlantic coasts of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and winters
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
south to the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
and west Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. Both the European and North American populations have been in long term decline, though active conservation measures have reversed the decline in the last few years at some colonies.
The tropical forms S. d. korustes and S. d. bangsi are resident breeders from east Africa across the Indian Ocean to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. They have more red on the bill. The long-billed and short-winged S. d. gracilis breeds in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
. The northwestern Indian Ocean holds populations of S. d. arideensis. Some authors suggest that only three races arideensis, gracilis and nominate dougallii should be retained.
This species breeds in colonies on coasts and islands. It nests in a ground scrape, often in a hollow or under dense vegetation, and lays one or two (rarely three) eggs. It is less defensive of its nest and young than other white terns, often relying on Arctic
Arctic Tern
The Arctic Tern is a seabird of the tern family Sternidae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe, Asia, and North America...
and Common Tern
Common Tern
The Common Tern is a seabird of the tern family Sternidae. This bird has a circumpolar distribution, breeding in temperate and sub-Arctic regions of Europe, Asia and east and central North America. It is strongly migratory, wintering in coastal tropical and subtropical regions. It is sometimes...
s in the surrounding colony to defend them. In smaller colonies, they may rarely mate with these other tern species.
As with other Sterna terns, Roseate Tern feeds by plunge-diving for fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, almost invariably from the sea; it is much more marine than allied terns, only rarely visiting freshwater lagoons on the coast to bathe and not fishing in fresh water. It usually dives directly, and not from the "stepped-hover" favoured by Arctic Tern
Arctic Tern
The Arctic Tern is a seabird of the tern family Sternidae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe, Asia, and North America...
. The offering of fish by the male to the female is part of the courtship display.
Unusually for a tern, the Roseate Tern shows some kleptoparasitic behaviour, stealing fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
from other seabirds, at British colonies most often from Puffins
Atlantic Puffin
The Atlantic Puffin is a seabird species in the auk family. It is a pelagic bird that feeds primarily by diving for fish, but also eats other sea creatures, such as squid and crustaceans. Its most obvious characteristic during the breeding season is its brightly coloured bill...
. This habit greatly increases their food collecting ability during bad weather when fish swim deeper, out of reach of plunge-diving terns, but still within reach of the deeper-diving Puffins.
This is a small-medium tern, 33–36 cm long with a 67–76 cm wingspan, which can be confused with the Common Tern
Common Tern
The Common Tern is a seabird of the tern family Sternidae. This bird has a circumpolar distribution, breeding in temperate and sub-Arctic regions of Europe, Asia and east and central North America. It is strongly migratory, wintering in coastal tropical and subtropical regions. It is sometimes...
, Arctic Tern, and the larger, but similarly plumaged, Sandwich Tern.
Roseate Tern's thin sharp bill is black, with a red base which develops through the breeding season, and is more extensive in the tropical and southern hemisphere races. It is shorter-winged and has faster wing beats than Common or Arctic Tern. The upper wings are pale grey and its under parts white, and this tern looks very pale in flight, like a small Sandwich Tern, although the outermost primary flight feathers darken during the summer. The adults have very long, flexible tail streamers and orange-red legs. In summer, the underparts of adults take on the pinkish tinge which gives this bird its name.
The call of the Roseate Tern is a very characteristic chuwit, similar to that of the Spotted Redshank
Spotted Redshank
The Spotted Redshank, Tringa erythropus, is a wader in the large bird family Scolopacidae. It breeds across northern Scandinavia and northern Asia and migrates south to the Mediterranean, the southern British Isles, France, tropical Africa, and tropical Asia for the winter...
, quite distinct from other terns. In winter, the forehead becomes white and the bill black. Juvenile Roseate Terns have a scaly appearance like juvenile Sandwich Terns, but a fuller black cap than that species.
In the late 19th century, these birds were hunted for their plumes which were used to decorate hats. More recently, their numbers have decreased in some regions due to increased competition and predation by large gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s, whose numbers have increased in recent times.
With their favouring partly hidden nest sites, the provision of nestboxes has proven a dramatic conservation success, with the birds taking to them very readily. This results in greatly increased breeding productivity with the protection given to the young from predatory birds like Herring Gulls. At one colony on Coquet Island
Coquet Island, England
Coquet Island is a small island of about , situated off Amble on the Northumberland coast, northeast England.The Island is owned by the Duke of Northumberland...
, Northumberland
Northumberland
Northumberland is the northernmost ceremonial county and a unitary district in North East England. For Eurostat purposes Northumberland is a NUTS 3 region and is one of three boroughs or unitary districts that comprise the "Northumberland and Tyne and Wear" NUTS 2 region...
, the population rose from 25 pairs (1997) to 92 pairs (2005) after nestboxes were provided. Similar measures have been undertaken at the Anglesey tern colonies
Anglesey tern colonies
Ynys Feurig, Cemlyn Bay and The Skerries Special Protection Area, also known as the Anglesey tern colonies, is a Special Protection Area covering three sites in Anglesey, North Wales which support breeding terns:* Ynys Feurig...
along with clearance of vegetation, in particular Tree Mallow.
Conservation status
In the UK the Roseate tern has been designated for protection under the official government's national Biodiversity Action PlanBiodiversity Action Plan
A Biodiversity Action Plan is an internationally recognized program addressing threatened species and habitats and is designed to protect and restore biological systems. The original impetus for these plans derives from the 1992 Convention on Biological Diversity...
. One of the main reasons given in the UK plan for threat to the species is global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
, creating an alteration of vertical profile distribution for its food source fishes. The Roseate Tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
AEWA
The Agreement on the Conservation of African-Eurasian Migratory Waterbirds is the largest of its kind developed so far under the Bonn Convention. It was concluded on 16 June 1995 at The Hague, the Netherlands and entered into force on 1 November 1999 after the required number of at least fourteen...
) applies.
The Canadian Wildlife Service lists the Roseate Tern as Threatened. The U.S. Department of Interior lists the northeastern population as Endangered and the Caribbean population as Threatened.