Dan's Feathursday Feature: Caspian Tern

You most likely know the swallow called the Purple Martin. Or even if you don't know the name of the bird, you have probably seen Martin houses—those white bird hotels perched on tall flagpoles erected in golf courses, school gardens and other open public areas. My favorite uncle helped me build one when I was a kid. The graceful Purple Martin enlivens our summer cityscape, thanks in large part to our help in providing them comfortable housing.

Take the Martin, expand it 3x, paint it white, dip its head and wing tips in black, stick on a massive orange-red bill, teach it to hunt fish instead of mosquitoes, and what do you have? A Water Martin, of course. We know it as the Caspian Tern, but its scientific name is Hydroprogne caspia--Water Martin of the Caspians.

Well named. Graceful in flight as any swallow, but disguised as a gull, you've surely seen this amazing bird along any Lake Michigan beach from late spring through early fall. It will cruise around, fifty to a hundred feet above the water, bright orange beak cocked downward, looking for small fish that are careless enough to loiter too long near the surface. With a meal in its sights, the Caspian Tern will often hover for a few seconds, then suddenly fold its wings and dive head-first toward its prey, adjusting course on the fly as the fish moves. It strikes the water like a javelin, and emerges with—one time in three, in my experience—a shiny, squirming fish, often impaled on its beak. On the fly, the tern will flip the fish in the air so it can be swallowed head-first, gulp down its meal, and then—I kid you not—wipe its mouth by dipping its beak in the water as it skims full-speed along the surface of the lake. I never tire of watching the acrobatics.

But there is one Caspian Tern habit I am a bit tired of. It has what I consider an obnoxious call. It's a cross between a cat in heat and fingernails on the chalkboard. And the Caspian Tern seems to know how to time its squawks for maximum effect. I'll be walking in Jackson Park lost in thought, or maybe completely engrossed in watching another bird. The tern closes in quietly, and then from fifty feet directly overhead it lets out a shriek that makes me duck and turn, expecting to find a witch on a broomstick. The tern's success rate on the scare-meter—one hundred percent, in my experience.

Frozen lakes give the Caspian Tern concussions, so it heads south for the winter before the waters start to freeze over. You'll have to wait until spring to see one again. I can walk in peace for about six months.

Dan's Feathursday Feature is a regular contribution to the COS blog featuring the thoughts, insights and pictures of Chicago birder, Dan Lory on birds of the Chicago region.