One of the European terns, colloquailly as 'marsh terns', that have a marked preference for freshwater habitats. This species is probably the most handsome of them even if its name is rather prosaically descriptive. It has an easterly bias in its European distribution and this one was photographed in Viira, Estonia last year.
Vagrants of this species occur most years in Ireland but they are usually juveniles with much drabber plumage. Any I have seen in Ireland have also been by the sea!
Africa (entire continent rather than south of Sahara)
AN
Antarctica
AO
Atlantic Ocean
AU
Australasia (Wallacea (Indonesian islands east of Wallace's line), New Guinea and its islands, Australia, New Zealand and its subantarctic islands, the Solomons, New Caledonia, and Vanuatu)
PAL
Eurasia (Europe, Asia from the Middle East through central Asia north of the Himalayas, Siberia and northern China to Japan)
IO
Indian Ocean
LA
Latin America (Middle and South America)
MA
Middle America (Mexico through Panama)
NA
North America (includes the Caribbean)
NO
Northern oceans
OR
Oriental Region (South Asia from Pakistan to Taiwan, plus Southeast Asia, the Philippines, and Greater Sundas)