25 June 2009

For me the common nighthawk is an iconic species.  Its diving courtship display so fascinated me as a ten-year-old that I developed a lifelong interest in birds.

Nighthawks used to be easy to find in my Pittsburgh neighborhood in summertime. I live across the street from a floodlit ballpark where I could watch them hawking insects at dusk in the bright ballpark lights.

But not anymore.  Common nighthawks have declined precipitously in Pittsburgh and the eastern United States, so much so that some states list them as an endangered species.

Common nighthawks are not hawks but nightjars, relatives of the whip-poor-will, whose diet consists solely of flying insects including mosquitoes, moths and flying ants.  They’re incapable of torpor and must eat hundreds of insects per night so they require warm weather and plentiful bugs. 

Nighthawks range widely in the Western Hemisphere migrating from Argentina to Canada.  They used to arrive in Pittsburgh around May 5 and leave by September 5.  During fall migration hundreds of birds would pass through at dusk for two weeks starting at the end of August. 

Surprisingly, common nighthawks have not been well studied, though new efforts are underway.  What is known is that in the northeastern U.S. they used to nest in natural areas.  Then in the 1890s they began to nest almost exclusively on gravel rooftops in cities and towns.  In the 1990s people replaced gravel roofs with rubber roofs and nesting opportunities disappeared.  Meanwhile something must have gone wrong in their breeding range or at their wintering grounds or on migration. Probably pesticides. Year after year fewer migrants leave in the fall and even fewer return in the spring.

Ten years ago there were several nesting pairs in my neighborhood but last summer there was only a lone individual calling for a mate who never came.  This year he called for two weeks and was gone.  I don’t think I’ll ever again see them nest in my neighborhood.

Considering their rapid decline, I may live to see common nighthawks go extinct east of the Mississippi just as peregrine falcons did when I was young.

With human help peregrines came back.  Can we save the nighthawk?

(photo from WikiMedia taken by Daniel Berganza near Miami, Florida.  Click the photo to see the original.)

When Chuck Tague sent me this picture of a scarlet tanager I was struck by something I had never noticed before.  The underside of this black and scarlet bird’s wings is neither black nor red, it’s white!

This got me thinking of other birds whose underwings are an unexpected color.

My favorite are those of the rose-breasted grosbeak.  The rose color from the male’s breast is repeated under his wing.  It’s a real trick to see this because he just won’t hold his wings open.  I discovered the color one day when I was sitting below a male grosbeak and he glided over my head to a nearby branch.  His color took my breath away.

Not colorful, but equally surprising are the black “armpits” of the black-bellied plover.  This bird is named for his breeding plumage but you won’t see a black belly on him in the winter when he visits the Atlantic coast from New Jersey to South America.

I remember the first time I tried to identify a non-breeding black-bellied plover.  It was February in Virginia Beach.  Slowly and carefully I examined a flock of three drab birds and tried very hard not to scare them so I could carefully note all their features.  I was a “newbie” to shorebirds and I could not figure them out.  For 15 minutes I watched those birds, had no idea what they were and was careful, careful not to startle them.  Then someone walked by with a dog, the birds flew, and I saw their black armpits.  Black-bellied plovers!  I certainly felt like a fool.

Do you have a bird whose underwing color surprised you?  Leave a comment and tell us about it.

(photo by Chuck Tague)