Great Tern Cheat Sheet: How to Identify Four Common Species
Terns are fascinating. The sight of a tern soaring effortlessly above the waves and diving elegantly after fish is undoubtedly a highlight of any beach visit. But in North America, they’re not the easiest birds to tell apart: most terns appear to have black caps, white and gray bodies, and long, pointed beaks, and behave similarly.
Use this tip sheet to distinguish between the four great terns of the United States: Caspian, Royal, Elegant, and Sandwich. To learn about all of our tern species, see the Audubon Guide to North American Birds. And to identify birds on the move, download Audubon’s free bird guide app.
This large, 19-inch-long tern is common along the southern Atlantic and Gulf and Caribbean Sea coasts, and in California in lesser numbers. The underside of its wings is white. It has an exceptional shaggy crest which is sometimes pointed in the back. The Royal Tern’s black crown recedes in early summer, leaving a patchy white head and forehead, as if bald. Pumpkin-orange beak. Moderately forked tail.
The Sandwich Tern is often seen with the Royal Tern, but is smaller at 17 inches long. It is found year-round around the Gulf of Mexico, southern Atlantic, and Caribbean Sea, where it nests on coastal beaches and barrier islands. Underwing white trailing to gray at tips. Like the Royal, its neat black crown with a slightly ruffled crest recedes shortly after the birds lay eggs in June; in late July, when individuals leave their nesting colonies, the forehead is almost entirely white. Distinguished especially by its black beak with a yellow tip. Slightly forked tail.
At 21 inches in length, the Caspian tern is the largest in the world – almost like a seagull in its bulk. In the United States, it is commonly found along the Atlantic, Pacific, and Gulf coasts, and it can also be seen inland along rivers, lakes, and marshes. The underside of the species’ wings is dark, as if immersed in blackish watercolours, unlike the other species listed here. Its spiky crest is not prominent, looking more like a long buzzcut. The large blood-red bill is edged in black. Slightly forked tail.
The elegant tern is 16 inches long and noticeably slender. It has a much more restricted range than the other species, as it is seen only on the west coast; it began breeding in California in 1959 and has since spread north. The underside of the wings is white. Its fabulous black crest is longer than that of the Royal Tern, sometimes long enough to strike the bird’s back. Its yellow-orange to orange beak is long and thin. Deeply forked tail.
This story was originally published in the Summer 2022 issue. To receive our print magazine, become a member by donate today.
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