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Bird of the Month

April: Terns

Learn about a different species of bird each month and find out how you can support birds along their migratory paths.

Bird of the Month - Terns

You can learn about a different species of bird each month! Join Dave Mehlman, director of The Nature Conservancy's Migratory Bird Program, as he answers questions about these fascinating creatures.

How are these birds chosen? Each month, we will feature a bird species from a photo taken by a member of our online Flickr™ community.

April's bird of the month — the tern — was taken by Flickr User: steffro1. See this photo on Flickr™ and in the header above.

Learn more about Terns

Q: Dave, this month we’ve got what look like some squabbling terns on a beach. Is the one on the right complaining, or is there something else going on?

Dave Mehlman: Yes, at first glance this appears to be two terns squabbling. However, if you closely at the right-hand bird, you can see that its feathers, particularly on the back and wings, are much whiter than the left-hand bird. There is also a black bar on the folded wing of the right-hand bird and the wing feathers themselves appear to be edged in white. These features tell me that the right-hand bird is a well-grown chick which is begging from its parent (the left-hand bird).

Q: The two in the back have black beaks — does that make them special?

Dave Mehlman: Good spot — there’s hope for you yet! The orange beaks of the front birds are a dead give-away that these two are royal terns. The black-beaked terns in the background, however, are sandwich terns, most likely, since these two species frequently nest together.

Q: I’ve read that royal and sandwich terns nest in these really dense colonies on the ground, with no more than a bill’s length apart between nests (speaking of a lot of squabbling). What’s the point of everybody raising their kids together like that?

Dave Mehlman: Yes, these two species characteristically nest in very large, dense colonies on low-lying islands just offshore. They need islands with little or no vegetation that are close to feeding areas — in fact, dredged spoil islands can make excellent nesting habitat, at least until they are colonized by plants. The point of such dense colonies, besides making it easy to gossip with the neighbors, is most likely to provide defense against predators. If a predator should happen to try to steal an egg or chick, there are literally thousands of reinforcements instantly available to chase the predator away.

Q: Speaking of nesting, don’t young royal terns do something interesting after they hatch?

Dave Mehlman: I have been on several tern nesting islands and the most fascinating thing to me is that the young, after they are old enough to walk, will leave their nests and form large aggregations or crèches on the islands, presumably also for protection against predators. But, the amazing thing is that they are still being fed by their parents. How a parent finds its individual chick among thousands of similar appearing and literally screaming chicks, is an amazing thing to think about. Somehow, amidst the din, the chick and parent recognize each other’s call and plumage and they find each other. Interestingly, there is great variation in plumage, leg and beak color between individual chicks, even though they eventually turn into almost identical-looking adults. This seems clearly related to helping adults identify their own chick.

Q: Caspian, least, elegant, great crested, lesser crested, sandwich, royal, Arctic— there are so many tern species and subspecies! Why is that? And don’t say “one good tern deserves another”!

Dave Mehlman: You always steal my best lines! It’s true, there are many, many species of terns in the world. It is a group found on all continents (yes, there’s even an Antarctic tern) and all species have very similar body forms, plumages and behaviors, with very few exceptions. I honestly don’t have a good explanation for this, other than apparently this combination of traits has proven very successful over time. The intriguing thing to me is that so many different tern species are “built” basically on the same body type and plumage: a long, narrow beak well adapted for plunge diving after fish; white or pale gray bodies; frequently a black cap (which may partially or fully disappear in the non-breeding season); frequently brightly colored legs and/or beaks in the breeding season, if not year-round; and very pointed wings. I guess those tern plumage features just never go out of style!

Q: What’s the range of these birds?

Dave Mehlman: Back to the birds in the photo…royal terns have a very wide range, though it is restricted to coastal areas. In North America, it breeds along the Atlantic, Pacific, and Gulf of Mexico coasts from Maryland and Virginia in the east and southern California in the west, south through Mexico into Central America. It is also found in the Caribbean and in scattered places in South America, including Argentina and Brazil. A completely different population of the species breeds in a small range off West Africa. The sandwich tern has a very similar range in North America, except that they do not breed on the Pacific Coast. In the Old World, they breed along the coast of Europe and in the Mediterranean, Black, and Caspian Seas.

Check back next month to learn about another species of bird. Your bird photo could be featured as the Bird of the Month! Submit your photo to our online Flickr community for consideration. Find out how »

How You Can Help Migratory Birds

You can help support our migratory birds conservation work and make a difference for birds like the sandwich and royal tern and for the environment when you use our safe and secure online donation form.

Photo: Sandwich and Royal Terns. Photo © Flickr User: steffro1.

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