"I have a question for you," wrote Deborah Stalker in an e-mail to the newsroom.

"I see many birds lined up on wires in town every day. Why do they all sit facing the same way?"

Instantly, I pictured the scene she was describing -- anywhere from a dozen to 100 pigeons or starlings or even mourning doves, perched together on a hydro line. In my imagination, they were facing the wintry sun, soaking in the slanting rays, trying to get warm. They'd have their breast feathers puffed out and might be blinking sleepily, like sunbathers lined up on a beach.

But then I thought of the wind and had to alter my mental scenario. If there was any sort of a chilling breeze, they'd be facing into it. A bird's feathers are contoured around its body, designed for flight, for sailing forward through the air. Brilliantly adapted for smooth navigation, they keep a bird warm at the same time by channeling moving air around its curved body, even when perched. The streamlined back and pointy tail ensure a bit of a vacuum to create lift in flight but not so much to act as a brake.

Barbs of the outer feathers have tiny interlocking hooks that lock them together to keep out drafts. When birds preen, they run those barbs through their beaks, combing them out and fastening them in place over the fluffy insulating feathers underneath, thereby trapping warm air against their skin. It's wonderful engineering.

Add rain to the picture and the flock of birds would definitely be facing into it, since those interlocking feathers run water off, too. If birds turn their backs to the wind, their feathers get ruffled and moisture might seep in -- not a good idea in a gale.

Of course, in a storm, they wouldn't be up on a wire at all but would find a sheltered roost out of the wind.

What birds gather together on wires? Mostly European starlings and rock pigeons, species that have adapted to living in cities around the planet, wherever European settlers started clearing and building.

Our native mourning doves often gather on wires near a cornfield in winter or in a neighbourhood with bird feeders. They spend a good deal of time together sitting and digesting, on the ground if it's bitterly cold and windy, in trees or on wires on milder days.

With the arrival of spring, we'll soon be seeing migrating swallows lined up on wires, too, resting after long flights from as far away as South America. These graceful, agile birds spend most of their lives in the air, zooming after insects. On wet, windy days, flocks gather on the leeward side of woodlots, where gnats and midges swarm.

Nature queries: 905-725-2116 or mcarney@interlinks.net.