Camping on a lake in late summer, we hear a loon calling. A loon calling at night is often answered by its mate, but this one is calling solo. Loons are water birds, only going ashore to mate and incubate eggs. Their legs are placed far back on their bodies, excellent for swimming but awkward for walking.
Loons are well equipped for their submarine maneuvers to catch fish. Unlike most birds, loons have solid bones that make them less buoyant and better at diving. They can quickly blow air out of their lungs and flatten their feathers to expel air within their plumage, so they can dive quickly and swim fast underwater. A loon shoots through the water like a torpedo, propelled by powerful thrusts of those strategically placed feet. When their quarry changes direction, loons can execute an abrupt flip-turn: they extend one foot laterally as a pivot brake and kick with the opposite foot to turn 180 degrees in a fraction of a second. Loons sometimes work together to chase schools of fish.
Loons are agile swimmers, and they move pretty fast in the air, too. Migrating loons have been clocked flying at speeds more than 70 mph. But because they're heavy, they need a lot of water to take off, and will run across the top of the water for sometimes hundreds of yards, flapping hard, to get enough speed to get airborne.