Sunday, March 28, 2010

Non-Stop Flight

If you've ever jumped out of an airplane, you'll appreciate this.  The little swift takes off from its nest and spends months in the air ... without landing anywhere.  Months!  Some spend nine or ten months continuously airborne in their migration, living off bugs in the air.  At night, they'll rise up to perhaps ten thousand feet on terrain-provoked air currents.  They probably nap while gliding, scientists suspect.

Swifts arrive in South Africa from Europe in October and November.  They'll head for home between January and March, all without having landed anywhere.

Nesting, when it happens, is always tucked away above the ground; chimneys are popular.  Swifts rarely land at ground level, although they will occasionally skim along the surface of water for a drink or a bath on-the-fly.

The common swift is beautifully designed with a torpedo-shaped body around six inches long, or about sparrow-size.  Its wingspan is wide in proportion at around sixteen inches, about twice that of a sparrow.  An impressively efficient metabolism and refined physiology make being continuously airborne possible.  They can top 100 mph in level flight.

So just for fun, imagine launching out your front door and into the air on a beautiful morning.  You notice the days are getting shorter, so you head south.  You cruise comfortably down to the Mediterranean and far beyond into southern Africa.  Meals are available along the way.  After a warm few months, lazing along in the warm southern air, you turn for home.  You'll spend a couple of months there relaxing and maybe raising some little swifts.  And next year, you'll bring the kids along to enjoy the view.  And the bugs.

Breeding grounds for the common swift (apus apus) include Europe, Asia, China, and Northern Africa. Their migration habitat includes all of sub-Saharan Africa. They have a stable population of perhaps 25 million which is enough, I guess.
Sometimes the world seems filled with interesting things I hadn't known.

Thanks and a hat-tip to Science Friday on NPR.