Great Northern Diver vs Cory's Shearwater

The Great Northern Diver (Common Loon) and Cory's Shearwater are distinct in appearance and habitat. The diver is a freshwater bird with a striking black-and-white plumage, while the shearwater is a pelagic bird with a more muted, brownish coloration. Both species are large, but their differing environments and behaviors make them unlikely to be confused in the field.

1. Habitat: Check the habitat first; divers are on lakes, shearwaters are at sea. 2. Plumage: Look for the diver's black-and-white pattern versus the shearwater's brownish tones. 3. Behavior: Note the diving behavior of the diver versus the gliding flight of the shearwater. 4. Vocalization: Listen for the diver's wails compared to the shearwater's cackles. 5. Season: Consider the season; divers are more likely inland during breeding, shearwaters are always at sea.

Both species are large birds, but the Great Northern Diver is typically more robust and heavier, whereas Cory's Shearwater is more streamlined.

The Great Northern Diver has a distinctive black-and-white checkered back and a black head in breeding plumage, while Cory's Shearwater has a more uniform brownish-gray back and a paler underside.

The diver is often seen alone or in pairs on freshwater lakes, diving for fish, while the shearwater is typically seen gliding over the ocean in flocks, using dynamic soaring.

Great Northern Divers are found on freshwater lakes during breeding and along coasts in winter, whereas Cory's Shearwaters are strictly pelagic, rarely coming to land except for breeding on islands.

The Great Northern Diver is known for its haunting wails and yodels, especially during the breeding season. Cory's Shearwater has a more guttural, cackling call, usually heard at night near breeding colonies.