Audubon Magazine / Summer 2022

The Big Tern Cheat Sheet: How to ID Four Common Species

In summer, North America’s four largest terns are near look-alikes. With a keen eye for detail you can tell them apart.
Royal Terns nest in a closely-packed crowd. About midway through the summer, their black crests recede at the crown, leaving a patchy white forehead. Photo: Walker Golder
A seemingly endless flock of Royal Terns, mostly white and gray birds with spiky black crests and bright orange beaks, nest in a closely-packed crowd. A single bird in the center and its tiny, fuzzy, light-colored chick look towards the camera.
Royal Terns nest in a closely-packed crowd. About midway through the summer, their black crests recede at the crown, leaving a patchy white forehead. Photo: Walker Golder
Words by Hannah Waters
Senior Editor, Audubon magazine
Published Summer 2022

Terns are mesmerizing. The sight of a tern effortlessly hovering over the waves and diving elegantly after fish is without fail a highlight of any beach visit. But in North America they aren’t the easiest birds to tell apart: Most terns seem to have a black cap, white and gray body, and long pointy bill, and to behave in similar ways.

Use this tipsheet to distinguish between the United States’ four big terns: Caspian, Royal, Elegant, and Sandwich. To check out all our tern species, see Audubon's Guide to North American Birds. And for IDing birds on the go, download Audubon's free bird guide app. 

Royal Tern

A group of Royal Terns, white and gray birds with a spiky black crest and bright orange bill.
Photo: Jenna Asperslag/Audubon Photography Awards

This large, 19-inch-long tern is common along the southern Atlantic and Gulf Coasts and the Caribbean Sea, and in California in fewer numbers. The underside of its wings is white. It has an outstanding shaggy crest that is sometimes spiked up in the back. The Royal Tern’s black crown recedes in early summer, leaving a patchy white head and forehead, as if it’s balding. Pumpkin-orange bill. Moderately forked tail.

Sandwich Tern

Two Sandwich Terns, white and gray birds with a spiky black crest and black bill with a yellow tip stand on the beach, one holding a fish in its beak.
Photo: Lorraine Minns/Audubon Photography Awards

The Sandwich Tern is seen often with Royal Terns, but it’s smaller, clocking in at 17 inches long. It’s found year-round around the Gulf of Mexico, southern Atlantic, and Caribbean Sea, where it nests on coastal beaches and barrier islands. White underwings trail to gray at the tips. Like the Royal, its crisp black crown with slightly spiky crest recedes soon after the birds lay eggs in June; by the end of July, when individuals leave their nesting colonies, the forehead is almost entirely white. Most distinguishable by its black bill with a yellow tip. Tail slightly forked.

Caspian Tern

A Caspian Tern, a mostly white and gray bird with a black crest, red-orange bill, and black undersides of wings, stands in shallow water swallowing a large fish.
Photo: Tim Timmis/Audubon Photography Awards

At 21 inches in length, the Caspian Tern is the largest in the world—almost gull-like in its bulk. In the United States, it’s commonly found along the Atlantic, Pacific, and Gulf Coasts, and can also be seen inland along rivers, lakes, and marshes. The underside of the species’ wings is dark, as if dipped in blackish watercolors, unlike the other species listed here. Its bristly crest is not prominent, looking more like a long buzzcut. Chunky, blood-red bill is tipped with black. Slightly forked tail. 

Elegant Tern

Two Elegant Terns, white and gray birds with a spiky black crest and orange bills, stand facing each other on a beach.
Photo: Sandrine Biziaux-Scherson/Audubon Photography Awards

The Elegant Tern is 16 inches long and noticeably slim. It has a far more restricted range than the other species, as it’s seen only on the West Coast; it began nesting in California in 1959 and has spread northward since. Underwings are white. Its fabulous black crest is longer than that of the Royal Tern, sometimes long enough to hit the bird’s back. Its yellow-orange to orange bill is long and slender. Deeply forked tail.

This story originally ran in the Summer 2022 issue. To receive our print magazine, become a member by making a donation today.