Great Northern Diver vs White-billed Diver

The Great Northern Diver (Common Loon) and the White-billed Diver (Yellow-billed Loon) are both large, aquatic birds with striking breeding plumages. The most reliable field mark is the bill: the Great Northern Diver has a black bill, while the White-billed Diver has a pale yellow or ivory bill. Both species have similar body shapes and plumage patterns, but their bills are the key distinguishing feature.

1. Bill Color: Great Northern Diver has a black bill; White-billed Diver has a pale yellow or ivory bill. 2. Breeding Plumage Pattern: Look for the more checkerboard pattern on the back of the Great Northern Diver. 3. Habitat: Consider the breeding habitat—Great Northern Diver on lakes, White-billed Diver in tundra regions. 4. Vocalizations: Listen for the distinctive calls of the Great Northern Diver.

Both species are similar in size, being large and robust loons.

In breeding plumage, both species have a black head and neck with white spots on the back. The Great Northern Diver has a more checkerboard pattern on the back, whereas the White-billed Diver has a slightly more uniform pattern. In non-breeding plumage, both species appear more muted, with grayish tones.

Both species are strong divers and piscivorous, often seen diving for fish. They are territorial during the breeding season.

The Great Northern Diver breeds on oligotrophic and mesotrophic lakes across Canada and Alaska, while the White-billed Diver breeds in low-lying tundra regions north of the tree-line. During winter, the Great Northern Diver is found along coasts and freshwater reservoirs, whereas the White-billed Diver is less commonly observed due to its remote breeding range.

The Great Northern Diver is known for its haunting yodels and wails, while the White-billed Diver's vocalizations are less well-documented but include similar calls.