This species is most abundant in Canada and the Northern United States. Common Loons breed on lakes and other waterways from western Greenland and west across Canada and the northernmost United States, including Alaska. Loons
nest on lakes and large ponds. Weather restricts habitat selection, because loons cannot nest on frozen water. They prefer to nest offshore, on islands, islets, or floating mounds of vegetation in shallow water. In winter, loons migrate to shallow coastal marine habitat.
The plumage of loons is black, white and gray. During the breeding season, Ccommon Loons have a black head with a white and black barred necklace, and a checkered pattern on their back. Male and female Common Loons look alike, though males are usually larger than the females.
Common loons breed once per year in the summer. They are thought to be monogamous, remaining with the same partner for life. The male and female build a nest approximately two feet in diameter of soil, grasses, moss or other vegetation. The nest is usually in a sheltered location near deep water,
allowing the male and female to swim to and from the nest undetected by predators. Often nests are built on islands or peninsulas projecting into the water. When the nest is completed, the female lays 1 to 3 (usually 2) brown eggs, one to two days apart. The male and female both incubate the
eggs, beginning after the first egg has been laid. Incubation lasts for 29 days. The chicks hatch asynchronously, up to a day apart. They stay in the nest for a day or two after hatching, after which time they leave the nest with the parents and return to shore only rarely.