The common loon is a duck-like sea bird with a thick, pointed bill and a distinctive black-and-white checkered pattern during breeding season. It visits the Chesapeake Bay in autumn and late winter to feed on open waters.
The appearance of the common loon varies depending on the time of year. During breeding season, loons have a distinctive black-and-white checkered back and “necklace” around the throat. The head and bill are black. In winter, loons have a mostly blackish black and a pale gray bill. The white throat has an irregular black indentation. Loons have a thick, dagger-like bill that it holds straight ahead and large, webbed feet. Their long body grows 28 to 36 inches long, and their wingspan reaches an average of 58 inches.
Loons live on the Chesapeake Bay’s open waters.
Loons begin arriving on the Chesapeake Bay in late September after migrating from its northern breeding grounds. By October and November, there are thousands of loons on the Bay. As winter draws near, large flocks of loons leave the Bay and continue flying southward to the Outer Banks of North Carolina. In February and early March, loons return to the Bay. At this time, they are in their distinctive breeding plumage. Soon after their arrival, loons begin their migration back to their northern breeding grounds.
The common loon feeds heavily on menhaden and other small fish. It constantly hunts throughout the day. To find prey, it peers below the water’s surface, then dives below the water to chase it down. Loons feast throughout autumn to hold themselves over during their winter molt, when they cannot swim or fly. When they return to the Bay in late winter, loons once again eat large amounts of fish in preparation for their return flight to the north.
Adults have few predators, but may be vulnerable to bald eagles and other large raptors. The loon may use its spear-like bill to defend itself against predators.
In flight, loons have a hunchbacked appearance. They hold their bill straight ahead and their large feet trail behind.
In winter, loons are mostly silent. During other parts of the year, they make several distinct calls, including a quivering wail. Common loons are famous for their calls, including the "tremolo," which is a wavering call given when a loon is alarmed or to announce its presence. Each male also has a signature yodel, which is its territorial claim; if the male moves to a different territory, his yodel will change.
Breeds in Canada and the Great Lakes region of the United States. Males and females will build their nest together in May or early June out of dead plant material, such as sedges and marsh grasses.