Loons
Gavia immer
The Common Loon (Gavia immer) is a large, iconic waterbird of northern lakes, known for its striking breeding plumage and haunting calls. These powerful, agile divers are well-adapted to aquatic life, spending most of their time on water and coming ashore primarily for nesting. They are considered indicators of aquatic ecosystem health.
Typical adult measurements.
Individuals and populations vary.
01 / The telltale details
Start with shape and behavior. Then look for the smaller details.
Black head and bill, white-and-black striped collar, and a boldly checkered black-and-white back. Red eyes are also characteristic.
Plain gray on the back and head with a white throat and underparts. The bill fades from black to gray.
Similar to non-breeding adults, with a pale scaly pattern on the back.
Thick, pointed, and typically held horizontally.
02 / A place in the world
During the breeding season, Common Loons prefer clear freshwater lakes with rocky shorelines, deep bays, and islands in forested landscapes. In winter, they inhabit coastal marine waters, large rivers, and ice-free inland lakes and reservoirs.
Common Loons breed across Alaska, most of Canada, and parts of the northern United States, as well as southern Greenland and Iceland. They winter along both coasts of North America, extending south to Florida, the Gulf Coast, and Mexico, and on the Atlantic coast of Europe.
Common Loons are migratory, moving from northern freshwater breeding grounds to coastal marine waters or large ice-free inland lakes for the winter. They migrate singly or in small flocks, often flying low over water along coastlines.
03 / Listen a little closer
Known for four main calls: yodels (territorial, by males), hoots (contact calls, especially with young), tremolos (alarm calls, often in flight), and wails (long-distance communication between mates).
04 / The life behind the feathers
Their primary diet consists of fish, which they catch by diving. They also opportunistically consume shellfish, aquatic insect larvae, crustaceans, leeches, and snails, especially when fish are scarce.
Common Loons are expert underwater swimmers and divers, propelling themselves with their feet to catch fish. They often swallow smaller prey underwater, bringing larger items to the surface to eat.
The female builds a nest of mud and aquatic vegetation, typically up to 60 cm in diameter, very close to the water's edge. They usually lay two to three olive-brown, lightly spotted eggs, and both parents tend to the young.
Highly territorial during the breeding season, males defend their territory with vocalizations. While generally solitary when feeding in winter, they may gather in loose flocks at night. Chicks can dive and swim within days of hatching and sometimes ride on their parents' backs.
One more reason to pay attention
Common Loons have dense, nearly solid bones, which makes them less buoyant and aids in diving.
They can concentrate oxygen in their leg muscles, allowing them to sustain strenuous underwater paddling and dive to depths of up to 60 meters.
Common Loons require a long 'runway' on water to take off due to their heavy bodies and the rearward placement of their legs.
05 / An eye for the difference
The Yellow-billed Loon has a pale, often yellowish, upturned bill, unlike the Common Loon's typically dark, straight bill.
The Red-throated Loon is smaller, has a thinner, often upturned bill, and in breeding plumage, displays a distinctive reddish throat patch.
Common Mergansers have a reddish bill and lack the white neck bands and checkered back pattern of breeding Common Loons.
AI-assisted species research. Prepared September 2026. Details can vary across regions and populations.