A large (28-36 inches) loon, the Common Loon in summer is most easily identified by its black head and bill, black-and-white “crosshatched” back, and conspicuous white breast patch visible immediately above the waterline. Winter Common Loons are dark above and pale on the breast, throat, and head, appearing slightly darker than the related Red-throated Loon (Gavia stellata). Male and female Common Loons are similar to one another in all seasons. The Common Loon inhabits parts of Eurasia (where it is known as the Great Northern Diver) and North America. In the New World, this species breeds across Alaska, Canada, Greenland, and the northern tier of the United States. Red-throated Loons breeding in North America spend the winter along the Pacific coast from southern Alaska south to central Mexico, along the Atlantic Coast from Nova Scotia to Florida, along the Gulf coast from Florida to eastern Mexico, and at a few locations in the interior southeast. In the Old World, this species breeds in Iceland, wintering along the coasts of Northern Europe. In summer, Common Loons breed in large lakes either on the tundra or in evergreen forests. During the winter, Common Loons are found along the coast in near-shore waters and on large bays and reservoirs. On migration, this species may be found on large bodies of freshwater in the interior. Common Loons primarily eat small fish, which they catch by diving. In appropriate habitats in summer, Common Loons may be seen nesting on small islands in lakes or directly on the lake shore. At this time of the year, birdwatchers may hear this species’ haunting “yodeling” calls on calm nights. During the winter, Common Loons are most easily observed out at sea through binoculars or spotting scopes, and may be seen floating low in the water, diving below the surface in pursuit of prey, or flying awkwardly close to the tops of the waves. This species is primarily active during the day, but calls at night during the breeding season.
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Bibliographic Citation: Rumelt, Reid B. Gavia immer. June-July 2012. Brief natural history summary of Gavia immer. Smithsonian National Museum of Natural History, Washington, D.C.
