Common loons are distinctive waterbirds, recognized by their striking black and white plumage during breeding season and their haunting, yodeling calls that echo across northern lakes. Each year, as seasons change, loons undertake extensive journeys, leaving their summer breeding grounds for warmer climates.
Why Loons Migrate
Loons migrate primarily because their northern freshwater breeding grounds become inhospitable during winter. These birds depend on open water for hunting fish and for gaining the necessary momentum to take flight. As autumn progresses, lakes in their breeding range begin to freeze, covering the surface and limiting their ability to forage and take off. The onset of ice formation effectively eliminates their access to food and restricts their mobility. This environmental pressure compels loons to seek out unfrozen waters where they can continue to dive and hunt throughout the colder months.
Timing of Southern Migration
The southern migration of common loons typically begins in late fall and extends into early winter, with adults usually initiating their departure from breeding lakes in late August or early September, though some may linger until late October or early November. Juvenile loons, however, often depart later, sometimes as late as November, after their parents have already left. Environmental cues, including decreasing daylight hours, dropping water temperatures, and initial ice formation on northern lakes, play a significant role in triggering this migratory movement and prompt loons to begin their journey south. Loons require a substantial open water “runway” to become airborne due to their dense bones and body structure, making ice formation a direct impediment to their survival. The exact timing of migration can vary slightly depending on the geographical region and the specific weather patterns of a given year, with some individuals delaying departure if an unseasonably warm fall extends the availability of open water.
Where Loons Spend Winter
Common loons spend winter in areas with open, unfrozen water, predominantly along coastal marine environments or large southern lakes and reservoirs. Their primary wintering grounds are along the Atlantic and Pacific coasts of North America, as well as the Gulf of Mexico. For example, loons from the Great Lakes region migrate to the Gulf of Mexico or the Florida coasts. Those from western Canada and Alaska head to the Pacific Coast, from the Aleutian Islands to Baja California. Loons breeding in eastern Canada and the northeastern United States overwinter along the Atlantic seaboard, from Massachusetts to Florida. While coastal waters are preferred, some loons also find suitable winter habitats on large inland lakes and reservoirs in southern states like Tennessee and South Carolina. These wintering areas provide the necessary open water and abundant fish for loons to survive until their northward migration in spring.