Editor's Note: Study of the mitochondrial DNA of terns, along with their plumage characteristics, have suggested that the heretofore broadly defined genus Sterna is paraphyletic. Reclassification of this genus now places Bridled Tern in the genus Onychoprion. See the 47th Supplement to the AOU Check-list of North American Birds for details. Future revisions of this account will account for this change.
The Bridled Tern is a strictly marine species with a large, nearly worldwide range across tropical and subtropical latitudes. Prior to the 1970s, it was considered a rare vagrant to North America, associated primarily with tropical storms. Pelagic bird study has shown it to be a relatively common seabird off the southeastern United States. Bridled Terns are uncommon but regular in the Gulf of Mexico and seasonally common in waters from Florida northward to Virginia. The Bridled Tern is a recently documented and very local breeder in the Florida keys where it first bred in 1987 near Boca Chica Key (Monroe County) in a colony of Roseate Terns (S. dougalli).
Although often compared to the Sooty Tern (Onychoprion fuscatus), the Bridled Tern's habits actually differ markedly from that species. It breeds in sheltered crevices in more dispersed nesting colonies and is more likely to be seen near land. At sea, the Bridled Tern seldom feeds in large flocks like its congener, instead exploiting a marine niche defined by a close association with marine flotsam, particularly pelagic Sargassum . Bridled Terns are highly unusual among terns (indeed most seabirds) in that some populations have synchronous, subannual breeding cycles that coincide with molt.
The specific name of Bridled Tern, anaethetus, is derived from a Greek root meaning senseless or stupid, a reference to its tameness and ease of capture by hungry sailors. In the West Indies, it shares the names Egg Bird and Booby with Sooty Tern. Other common names from outside the Western Hemisphere include Brown-winged Tern, Panayan Tern, Dog Tern, and Smaller Sooty Tern.
Most individuals seen off the southeastern United States presumably disperse from the closest major breeding sites in the Bahama Islands and Greater Antilles. Other breeding colonies near the United States occur in the Lesser Antilles, very locally along the east coast of Central America, and off the coast of northern South America. Diet, breeding, and population status of Bridled Terns remain poorly studied in the Western Hemisphere, where breeding populations are apparently small and remain vulnerable to coastal development.