Elegant Tern
Thalasseus elegans
This is a medium-large tern, with a long, slender, slightly downcurved orange bill, pale gray upperparts and white underparts. It is 39–42 cm (15–17 in) long with an 76–81 cm (30–32 in) wingspan, and a weight of 190–325 g (6.7–11.5 oz). Its legs are black. From late summer to winter, the forehead becomes white. The black of the crest that comes down from the crown extends through the eye, creating a small black "smudge" in front of the eye even in winter plumage. On royal terns, the black crest stops at the eye, while lesser crested tern has a less shaggy crest.
ID text from Wikipedia, CC BY-SA 4.0
Royal Tern
Thalasseus maximus
This is a large tern, second only to the Caspian tern among terns in the Americas, but is unlikely to be confused with this "carrot-billed" giant, which has extensive dark underwing patches. Adults have an average wingspan of 130 cm (51 in) for both sexes, with a range from 125–135 cm (49–53 in). Its bill-to-tail length ranges from 45–50 cm (18–20 in) and the weight is anywhere from 350–500 g (12–18 oz). The Old World West African crested tern T. albididorsalis and greater crested tern T.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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