Pacific Loons are long-distance migrant waterbirds of the Nearctic which winter almost exclusively in coastal waters in North America. A significant number of Pacific Loons winter along the fringe of the Neotropical zone, along the northwestern Mexican coast. Large numbers are thought to winter in the Gulf of California, with other significant concentrations noted along the Pacific Coast of Baja California. In winter, when the species is encountered in Neotropical waters, it is dark grayish-black above with a paler gray hindneck, white throat and foreneck, and white underparts. Shape is important in helping to separate Pacific Loon from the similar Common Loon; Pacifics have smaller, less angular bills and smooth head contours, as well as an even, straight border between the dark hindneck and white foreneck. They dive underwater to hunt fish and crustaceans in the winter, typically in productive nearshore waters.