Common Loon is an impressive, Holarctic-breeding waterbird that reaches the Neotropical region in winter. Wintering birds along both coasts of northern Mexico arrive in late fall, departing March-April to return to breeding grounds across the boreal forest of Canada and northern United States. Basic plumaged Common Loons are largely gray-brown above with pale faces and underparts, typically showing a large bill, angular head shape, and jagged border between the dark hindneck and white foreneck. By early spring, many adults have started molting into breeding (alternate) plumage, the striking glossy black plumage highlighted by red irides, a white checkerboard on the back, white collar on the neck, and white underparts. Common Loons are frequently heard yodeling at wintering sites as well as during migratory flight and on the breeding grounds. They dive underwater and hunt fish and crustaceans with foot-propelled swimming.