The Great Sailing Bird

Years ago, a friend of mine took a snapshot of a flying bird. The photograph isn't great, but the bird is: it looks sculptured, artificial, a composition in colors of fog and cloud. It's also huge.

"That bird looked like a cross between a seagull and a Cessna," my friend reported. He wasn't far wrong, at least about size. With a wingspan that can exceed 11 feet, the wandering albatross is the largest seabird in the world.

But it doesn't wander every sea. My friend took his photograph from the deck of a ship nearing Antarctica, in the most likely waters to find these rare birds. They live only in the Southern Hemisphere, usually very far south.

That limitation has given me occasional regrets, since I'd like to see one of these giants someday. Other kinds of albatross visit Alaska waters; why not wandering ones? Why are they so stubbornly southern?

The answer has been found. French scientists Pierre Jouventin and Henri Weimerskirch, who reported their work in the February 22 issue of Nature, deduced the reason in the course of a study to investigate feeding zones and ranges of wandering albatrosses.

Finding out anything about the feeding habits of a pelagic bird (that is, one found far offshore) is a tricky business. A little bit has been learned by serendipity at sea, because an observer happened to be in the right place at the right time to see a bird catching its dinner. A lot more has been learned by what amounts to banditry on shore, when researchers captured birds returning from feeding trips and--one way or another--appropriated the contents of their stomachs. Jouventin and Weimerskirch added new technology to these possibilities, and came up with the first successful tracking of a bird by satellite telemetry.

They worked with six wandering albatrosses nesting on tiny Possession Island in the southwestern Indian Ocean. The scientists captured male birds sitting on eggs, fitted them with tiny battery-powered radio transmitters, and released them back onto their nests. Within a few days, each of the birds had been relieved of incubating duties by its mate, and each had set off across the ocean in search of food.

Far above, satellites noted where the broadcasting birds went, and retransmitted location and time information to a data analysis facility in France. As each radio-bearing albatross returned to the island, it was again captured, relieved of its transmitter, and allowed to take its turn at nest-sitting duties. The albatross colony returned to normal while the scientists turned to working up the satellite-gathered information.

What they found made some truly impressive statistics. The longest single trip by a monitored bird covered 15,200 kilometers (9400 miles), about as long as the distance between Pt. Barrow and Capetown, South Africa. (Such long trips, with birds absent over the ocean for a month or so, are possible for wandering albatrosses during the breeding season only when their partners are sitting on eggs. With chicks to feed, each adult can be away from home only for a few days.) The birds flew at speeds of up to 80 kilometers (50 miles) an hour.

Those long, fast flights take very little flapping. Observers long knew that wandering albatrosses can operate like sailplanes, tilting their long wings to catch the wind. The satellite data showed that they also operate a bit like sailing ships, gliding downwind as they leave their home island, and tacking back and forth against lateral winds on the return leg of their long journeys. The wind is actually their primary power source.

Like the giant sailing ships of the last century, these giant sailing birds need a lot of wind. The oceanic areas where wandering albatrosses seek out their food are where the winds are most strong and most regular of any place on Earth. In the great circumpolar belt of the southern ocean, low-pressure systems come spinning through one after another, particularly during the austral autumn and winter when the birds are rearing chicks.

So, though it may be hard for Alaskans to believe, particularly for those who live in the Aleutians, wandering albatrosses don't live here because our weather's too good. We just don't have enough wind.