The Sandwich tern (Thalasseus sandvicensis)
This bird has no subspecies. Two former subspecies are now treated as a separate species, Cabot's tern (T. acuflavidus); this breeds on the Atlantic coasts of North America, northern and eastern South America, and has wandered to Western Europe. Cabot's tern was separated from Sandwich tern as it is genetically closer to elegant tern than to Sandwich tern.
Description
left|thumb|Juvenile plumage, Northumberland, UK
thumb|Calls of adults and young, Norfolk, England
thumb|Eggs, Collection [[Museum Wiesbaden]]
This is a medium-large tern, long with an wingspan, which is unlikely to be confused within most of its range. The weight ranges from 200–300 g; males average slightly heavier than females, but with much overlap.
The thin, sharp bill is black with a yellow tip. Its short legs are black. Its upper wings are pale grey and its underparts white, and this tern looks very pale in flight, although the primary flight feathers darken during the summer. The primary feathers also differ, with Sandwich tern having a broad white margin on the inner web, grey on Cabot's; this white fringe wears off through the summer, giving Sandwich tern primaries a distinctive 'hook tip' in late summer, while Cabot's primaries remain symmestrical as the grey web is more resistant to wear. while those breeding on the Caspian Sea coasts migrate to the Indian Subcontinent, south to Sri Lanka.
Status
The Sandwich tern has an extensive global range estimated at . It has a population estimated at 460,000–500,000 individuals. Population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons the species is evaluated as least concern.
Gallery
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File:Sandwich tern (Thalasseus sandvicensis) in flight 4.jpg|Sandwich tern in flight, Dorset, UK
File:Thalasseus sandvicensis - Sterne Caugek - Saint Brevin les Pins 2022 11.jpg|Plunge-diving Sandwich tern
File:Thalasseus sandvicensis - Sterne Caugek - Saint Brevin les Pins 2022 12.jpg|Plunge-diving Sandwich tern
File:Sterna sandvicensis Brandseeschwalbe.jpg|Sandwich tern approaching its waiting offspring with a fish
File:3-point tern (Sandwich, Common & Roseate Terns, St Mary's Island, Northumberland).jpg|Sandwich tern (left) with a common tern (centre) and a roseate tern (right)
File:Колонії крячків на міщаній косі.jpg|Breeding colony in Tuzly Lagoons National Nature Park, Ukraine
File:Thalasseus sandvicensis, Heligoland.jpg|Sandwich terns on Düne, Heligoland
File:Kentsk tärna (Thalasseus sandvicensis)-Ystad-2017.jpg|Sandwich terns resting in Sweden.
</gallery>