About Thalasseus maximus (Boddaert, 1783)
This species is the royal tern, with the scientific name Thalasseus maximus (Boddaert, 1783). It is a large tern; among terns in the Americas, it is second only in size to the Caspian tern. It is unlikely to be confused with the Caspian tern, often called the "carrot-billed" giant, which has extensive dark underwing patches. For adult royal terns of both sexes, average wingspan is 130 cm (51 in), with a range of 125–135 cm (49–53 in). Total length from bill to tail ranges from 45–50 cm (18–20 in), and body weight ranges from 350–500 g (12–18 oz). Two related species, the Old World West African crested tern (T. albididorsalis) and the greater crested tern (T. bergii), are the same size as the royal tern. Vagrant royal terns in Europe require careful documentation to distinguish them from the West African crested tern, which has also been recorded in Europe. The royal tern may also be confused with the smaller elegant tern (T. elegans); the elegant tern has a longer but more slender, slightly downcurved bill, and a longer crest. The royal tern has a stout orange-red bill, pale silvery-gray upperparts, and white underparts. Its legs are black. During spring, at the time of courtship and the start of the breeding season, the entire crown of the royal tern is black, with a shaggy, erectable crest on the nape. From early summer into late winter, the black coloration first becomes patchy, then the forehead and upper crown turn fully white, with black retained only on the nape. For northern populations, the royal tern's molt out of breeding plumage happens about two months earlier than the elegant tern's — in June, compared to August for the elegant tern — and results in more extensive white plumage on the head. Juvenile royal terns are similar to non-breeding adults, but differ in having darker gray to blackish markings on the wings, and a yellower bill. The calls of the royal tern are usually short, clear shrills. Some of these shrills sound like kree or tsirr; the species also produces a longer, rolling, more melodious plover-like whistle. The royal tern is found on both coasts of the Americas. In the northeastern part of its range, during the breeding season (April to July), it occurs primarily from Texas to Virginia, with scattered breeding records as far north as Long Island, New York, and as far south as French Guiana, on several Caribbean islands. It also breeds in the southeastern part of its range, from southeastern Brazil south to Chubut Province in Argentina. In the eastern part of the Americas, the royal tern's wintering range extends from North Carolina south to Panama, the Guianas, and throughout the Caribbean. The western population of royal terns nests from California to Mexico and winters from California south to Peru. Royal terns that breed in Argentina are resident or disperse into Brazil.
