22. Gaviiformes (Loons)

The five living loon species of the order of Gaviiformes constitute the genus Gavia. Loons inhabit only in the Northern Hemisphere, where they breed on inland lakes and ponds and in winter along seacoast. The fish-eating divers have webbed toes and bear a superficial resemblance to grebes. Like grebes, the loon's muscular legs are set far back on the body, an adaptation for foot-propelled diving. All loons are decent fliers, though the larger species have some difficulty taking off and thus must swim into the wind to pick up enough velocity to become airborne. Only the red-throated diver (G. stellata) can take off from land. Once airborne, their considerable stamina allows them to migrate long distances southwards in winter, where they reside in coastal waters.