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The roseate tern (''Sterna dougallii'') is a species of tern in the family Laridae. The genus name ''Sterna'' is derived from
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th ...
"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.


Taxonomy

English naturalist George Montagu described the roseate tern in 1813. Genetically, it is most closely related to the white-fronted tern (''S. striata''), with their common ancestor a sister lineage to the black-naped tern (''S. sumatrana''). This species 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 The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both 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, most notably at
Rockabill Island Rockabill () is a group of two islands, "The Rock" and "The Bill", lying in the western Irish Sea about 6 kilometres east-north-east of Skerries, County Dublin, Ireland. An alternative Irish name, ''Carraig Dhá Bheola'', meaning ''Two Li ...
off the coast of Dublin, Ireland, which now holds most of the European population (about 1200 pairs). The tropical forms ''S. d. korustes'' and ''S. d. bangsi'' are resident breeders from east Africa across the Indian Ocean to
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
. They have more red on the bill. The long-billed and short-winged ''S. d. gracilis'' breeds in
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
and
New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...
. The north-western Indian Ocean holds populations of ''S. d. arideensis''. Some authors suggest that only three races ''arideensis'', ''gracilis'' and nominate ''dougallii'' should be retained.


Description

This is a small-medium tern, long with a wingspan, which can be confused with the common tern, Arctic tern, and the larger, but similarly plumaged,
Sandwich tern The Sandwich tern (''Thalasseus sandvicensis'') is a tern in the family Laridae. It is very closely related to the lesser crested tern (''T. bengalensis''), Chinese crested tern (''T. bernsteini''), Cabot's tern (''T. acuflavidus''), and ele ...
. The 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.


Behaviour and ecology


Food and feeding

As with other ''Sterna'' terns, roseate tern feeds by plunge-diving for
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
, 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 Arctic tern (''Sterna paradisaea'') is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe (as far south as Brittany), Asia, and North America (as far south ...
. The offering of fish by the male to the female is part of the courtship display. Unusual for a tern, the roseate tern shows some kleptoparasitic behaviour, stealing
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
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. 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.


Breeding

This species breeds in colonies on coasts and islands, at times with other seabirds. In Australian territory, it has been recorded nesting alongside the black-naped tern (''S. sumatrana''),
lesser crested tern The lesser crested tern (''Thalasseus bengalensis'')Bridge, E. S.; Jones, A. W. & Baker, A. J. (2005)A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution. ''Molecular Ph ...
(''Thalasseus bengalensis''), crested tern (''T. bergii''), fairy tern (''Sternula nereis''),
bridled tern The bridled tern (''Onychoprion anaethetus'') is a seabird of the family Laridae. It is a bird of the tropical oceans. The scientific name is from Ancient Greek. The genus comes from ' meaning "claw" or "nail", and , meaning "saw". The specific ...
(''Onychoprion anaethetus'') and silver gull (''Chroicocephalus novaehollandiae''). 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 The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...
and common terns in the surrounding colony to defend them. In smaller colonies, they may rarely mate with these other tern species. The white-bellied sea-eagle (''Haliaeetus leucogaster'') and silver gull are known to prey on eggs and chicks, while the
turnstone Turnstones are two bird species that comprise the genus ''Arenaria'' in the family Scolopacidae. They are closely related to calidrid sandpipers and might be considered members of the tribe Calidriini. The genus ''Arenaria'' was introduced by ...
(''Arenaria interpres''), black rat (''Rattus rattus'') and King's skink (''Egernia kingii'') are suspected predators.


Vocalisations

The call of the roseate tern is a very characteristic ''chuwit'', similar to that of the spotted redshank, quite distinct from other terns.


Conservation status

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 Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century ...
s, whose numbers have increased in recent times. This species, as of 2019, is the UK's rarest breeding seabird. The largest European colony, accounting for more than 75% of the European population, is in Ireland, at
Rockabill Island Rockabill () is a group of two islands, "The Rock" and "The Bill", lying in the western Irish Sea about 6 kilometres east-north-east of Skerries, County Dublin, Ireland. An alternative Irish name, ''Carraig Dhá Bheola'', meaning ''Two Li ...
,
County Dublin "Action to match our speech" , image_map = Island_of_Ireland_location_map_Dublin.svg , map_alt = map showing County Dublin as a small area of darker green on the east coast within the lighter green background of ...
. In 2013, 1213 pairs nested at Rockabill. The colony at
Lady's Island Lake Lady's Island Lake () is a brackish lake in the south of County Wexford, Ireland. The lake is technically a back-barrier seepage lagoon, one of only two in Ireland. The other is nearby Tacumshin Lake. The lake has no natural outlet, but is sepa ...
,
County Wexford County Wexford ( ga, Contae Loch Garman) is a county in Ireland. It is in the province of Leinster and is part of the Southern Region. Named after the town of Wexford, it was based on the historic Gaelic territory of Hy Kinsella (''Uí C ...
, is also of crucial importance, with 155 pairs nesting there in 2013. 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 Herring gull is a common name for several birds in the genus ''Larus'', all formerly treated as a single species. Three species are still combined in some taxonomies: * American herring gull (''Larus smithsonianus'') - North America * European he ...
. At one colony on Coquet Island,
Northumberland Northumberland () is a county in Northern England, one of two counties in England which border with Scotland. Notable landmarks in the county include Alnwick Castle, Bamburgh Castle, Hadrian's Wall and Hexham Abbey. It is bordered by land ...
, 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 ''Malva'' is a genus of herbaceous annual, biennial, and perennial plants in the family Malvaceae. It is one of several closely related genera in the family to bear the common English name mallow. The genus is widespread throughout the temper ...
. In 2018, for the first time in more than a decade, a pair fledged two chicks on the Skerries, off Anglesey after a RSPB project over previous years involving wardening, newly designed nest boxes being placed strategically around the islands along with lures playing roseate tern calls and hand-made decoys. In the UK the roseate tern has been designated for protection under the official government's national Biodiversity Action Plan. One of the main reasons given in the UK plan for threat to the species is
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
, 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.


References


External links

* Roseate tern
Species text in The Atlas of Southern African Birds

Roseate tern: Madeira Birds
{{Taxonbar, from=Q321293 roseate tern Birds of Europe Birds of Macaronesia Birds of the Indian Ocean Birds of Southeast Asia Birds of Australia Birds of Melanesia roseate tern Birds of the Dominican Republic Taxa named by George Montagu (naturalist) Articles containing video clips