Distribution

Figure 1. Distribution of the Common Loon in North America.

Figure 2. Common Loon migration.

The Americas

Breeding Range

Restricted to freshwater habitats of North America (including Greenland) and Iceland (Figure 1). In Canada and Alaska, generally found nesting north to edge of the taiga shield. Breeding pairs rarely occur in tundra and coastal plain areas of Beaufort Sea (Johnson and Herter 1989), including Alaska (Meehan and Jennings in Johnson and Herter 1989) and are generally restricted to mainland North America except for tundra of Baffin Island. Similar coastal plain breeding populations occur in western Greenland and Iceland. Southern extent of breeding range has retracted from historical occurrences. However, recent recolonization of some southern peripheral areas has occurred, particularly in New England.

In the United States, currently breeds in isolated areas of w. and e. Washington, n. Idaho (breeding attempts are intermittent), nw. Montana, a disjunct population in nw. Wyoming (Yellowstone National Park and Shoshone National Forest), n.-central North Dakota (Turtle Mountains), the upper Great Lakes (south through northern Minnesota, Wisconsin and Michigan’s Lower Peninsula), New York’s Adirondack Mountains, parts of the St. Lawrence River and nearby area, and much of n. New England, except for a disjunct population breeding in central Massachusetts. In Canada, southern extent of breeding range extends to the U.S. border except in southeastern Alberta, southern Saskatchewan, southern extreme of Manitoba, and far s.-central Ontario.

For details on numbers and distribution, see Demography and Populations: range/status.

Summer Nonbreeding Range

In summer, nonbreeders found throughout much of North America. One- and two-year olds generally remain on the ocean, but there is evidence from banded individuals that young are mobile. Several immature loons banded in the Great Lakes have been re-observed or recovered from the mid-Atlantic Coast, particularly along the North Carolina barrier islands (BRI, unpubl. data), and from as far north as the Canadian Maritimes (McIntyre 1988). A small percentage of one- and two-year old loons migrate to interior lakes. At Whitefish Point, Michigan, migrants in basic plumage (i.e., one-year-olds) are regularly observed in late May and early June (Ewert 1982). In New England and the western U.S. small numbers in basic plumage regularly over-summer on interior lakes.

Winter Range

Over-winter on Pacific and Atlantic coasts, including the Gulfs of California and Mexico (Figs. 1, 2). Typically occupy inshore waters but may range up to 100 km offshore across the continental shelf (Lee 1987a, Haney 1990, Kenow et al. 2002). Southern limit stretches to the Florida Keys (Evers and Jodice 1995). In Mexico, regularly over-winters along the entire Baja California peninsula, rarely ranging further south into central Mexico (Howell and Webb 1995, Edwards 1998). Northern limits on the western Atlantic Coast span the Newfoundland shoreline; this may be the northern limit as Merkel et al. (2002) did not record Common Loons during intensive March surveys along sw. Greenland.

On the Pacific Coast, wintering loons range north into the Aleutian Islands of Alaska. Interior over-wintering loons are a minor component of the population. Some over-wintering areas are weather dependent, while others are used consistently, including reservoirs in central Tennessee and n. Alabama. Records known from Cuba (Garido and Kirkconnell 1993) and Bermuda (Amos 1991).

Outside The Americas

Breeding Range

Common breeder in Iceland, rare on Bear I. (Barents Sea shelf, 74°20'N, 18°45'–19°15'E; Williams 1971); one report of breeding in Scotland (hybrid pair, 1970), but unreported since then (R. Dennis, pers comm.).

Winter Range

Eastern Atlantic Coast wintering areas encircle Iceland and the western European shores of the North Sea. Also reported in Azores and accidental in nw. Africa along Algeria (Etchécopar and Hüe 1964); casual to Black Sea. Icelandic coast birds may be North American breeders (Gudmundsson 1972). Rarely over-winter in Russia on Komandorskiye (Commander) Is.; Gerasimov and Kalyagina (1997) did not observe Common Loons in the spring migration of 3,200 loons of mixed species in 1993 or 6,300 in 1994. Common Loons could be sparingly distributed further south as suggested by recent evidence from satellite transmissions of n. Alaska breeding populations of Red-throated (Gavia stellata) and Yellow-billed loons that shows these species over-wintering along the w. Pacific Ocean, south and west to coastal China (J. Schmutz, pers. com.).

Historical Changes

Has retreated from former southern range limits in ne. California, n. Iowa, s. Minnesota, n. Illinois, s. Wisconsin, n. Indiana, s. Michigan, n. Ohio, ne. Pennsylvania, s. Ontario, and in part New England, where southern extent of past breeding as far as Connecticut remains questionable (Newberry 1857, Ridgway 1895, Harlow 1908, Dinsmore et al. 1984, Cadman et al. 1987, Janssen 1987, McIntyre 1988, Peterjohn 1989, Bevier 1994). Breeding in 1980s in Pennsylvania (Street and Wiltraut 1985) and from 1970s to present in Massachusetts (Blodget and Lyons 1988) suggest incipient recolonization

Fossil History

The paleontological record of loons is incomplete (Emslie 1998, Olson and Rasmussen 2001). A loon-like fossil, Neagaeornis wetzeli, was found from the Cretaceous, but it remains unclear whether this is a direct ancestor of Gavia (Olson 1992). Gavia ancestry is likely linked to Colymboides, an extinct genus. The oldest Colymboides, C. anglicus, unearthed in England was named from a single coracoid bone in the Eocene 40mya (Storer 1956). The split between Gavia and Colymboides likely occurred around then (Olson and Rasmussen 2001).

Another Colymboides , C. minutus, was prevalent during the Oligocene (18 mya), but did not give rise to Gavia. Several species of Gavia have been identified from the Miocene: G. egeriana, G. schulzi, G. moldavica, G. brodkorbi, and G. panadoxa (Olson and Rasmussen 2001), but the relationship among these species is unclear and all represent extinct lineages. The only fossil species present from the Pliocene (4.8 mya) likely to have given rise to G. immer is G. fortis. The sister clade of G. immer and G. adamsii (Yellow-billed) split recently (< 1 mya) (Storer 1988).