Pacific Diver vs Great Northern Diver

In short

The Pacific Diver (Gavia pacifica) and Great Northern Diver (Gavia immer) can be distinguished by size and bill shape. The Great Northern Diver is larger with a more robust bill, while the Pacific Diver is more slender and smaller. Both species are similar in plumage but differ in habitat preferences during breeding and wintering seasons.

Identification tips

• Size and bill shape: The Great Northern Diver is larger with a more robust bill.
• Breeding plumage: Look for the black head and white necklace of the Great Northern Diver versus the gray head of the Pacific Diver.
• Habitat: Note the breeding habitat; Pacific Divers prefer smaller Arctic ponds, while Great Northern Divers choose larger lakes.
• Vocalizations: Listen for the more complex calls of the Great Northern Diver.

Size

The Great Northern Diver is significantly larger than the Pacific Diver, with a more robust and heavier build.

Plumage

Both species have similar plumage with dark upperparts and white underparts. However, the Pacific Diver has a more uniform gray head and neck during the breeding season, while the Great Northern Diver has a black head with a distinctive white necklace pattern.

Behaviour

Both species are diving birds primarily feeding on fish, but the Great Northern Diver is known for its territorial behavior during the breeding season.

Habitat

The Pacific Diver breeds on freshwater ponds in the Arctic and Subarctic tundra, while the Great Northern Diver breeds on larger oligotrophic and mesotrophic lakes. In winter, the Pacific Diver is mostly marine, whereas the Great Northern Diver can be found along coasts and on freshwater reservoirs.

Voice

The Great Northern Diver is known for its haunting calls, which are more varied and complex compared to the Pacific Diver's simpler vocalizations.