Royal Tern (Thalasseus maximus) [XC621076]
by Paul Driver from Albufera Mar Chiquita, Buenos Aires, Argentina (flight call)
Royal Tern (Thalasseus maximus) [XC797960]
by id from Fort Rosecrans National Cemetery, San Diego, California, United States (flight call)
Subspecies
Sometimes considered to form superspecies with Greater Crested Tern (Thalasseus bergii). Racial variation questionable.
The following 2 subspecies are recognised:
albididorsalis (Hartert, 1921) - Mauritania to Guinea, occasionally further S. Winters south to Namibia.
maximus (Boddaert, 1783) - Southern California to Sinaloa, and Maryland (rarely New Jersey) to Texas, and through West Indies to the Guianas and possibly Brazil, with disjunct breeding populations on Yucatán, and in southern Brazil, Uruguay and northern Patagonia. Winters south to Peru and to Uruguay and Argentina.