The common loon, scientifically known as Gavia immer, is native to much of North America. Its geographical distribution includes Canada, the northern United States, and parts of Greenland during the breeding season. During the non-breeding season, common loons can be found along the Atlantic and Pacific coasts of North America, extending from Alaska to Mexico and the Gulf Coast.

Common loons typically inhabit freshwater lakes and large ponds during the breeding season. They prefer clear, undisturbed bodies of water with abundant fish populations and enough space for takeoff and landing. During the winter, they migrate to coastal marine environments, where they favor sheltered bays and estuaries.

As skilled divers, common loons have adapted to a primarily piscivorous diet, feeding on a variety of fish and invertebrates. Their ecological niche involves hunting underwater using their sharp eyesight. Loons require aquatic environments with ample prey availability and isolation from significant human disturbance, which is crucial for their nesting and raising young. Habitat variations do occur, particularly in response to regional availability of suitable water bodies.