Anyone who has paddled a quiet lake in northern Canada may have heard the eerie, wavering call of the common loon. Five species of loon exist worldwide, and the common loon breeds across much of Canada's boreal forest, from the Yukon to Newfoundland. The bird's haunting cry carries for great distances across still water and is often the first sound campers notice at dusk. Today the loon is celebrated as a national symbol and even appears on the one-dollar coin, the "loonie." Yet beneath this familiar image lies a creature whose body is shaped almost entirely for life underwater.
Like few other birds, loons are built for diving rather than for walking. Their legs sit far back on the body, which makes them clumsy on land but powerful in the water. Unlike most birds, loons have nearly solid bones rather than hollow ones, which reduces their buoyancy and lets them sink and chase fish to depths of sixty metres. A loon can stay submerged for several minutes on a single breath. These same adaptations, however, leave it almost unable to take off without a long stretch of open water for a running start.
