From Opus

Alternative names: White-billed Diver; Yellow-billed Diver

Photo by Cancoot
Photo taken: Deep Bay, British Columbia, Canada

Gavia adamsii

[edit] Identification

The largest diver
L. 75-91cm
W. 147cm

• Large pale bill
• Straight culmen with angled lower mandible gives a characteristic appearance enhanced by habit of holding bill at an upward angle as in much smaller Red-throated Diver.

[edit] Adult Breeding

• White-chequered black back
• Glossy black head with white "necklaces"
• Differs in large, yellowish-white bill

[edit] Adult Non-breeding

• Generally paler, particularly around the head and hindneck
• Face much whiter with dark eye isolated in white face
• Head and neck paler than back
• At all seasons bill is the best distinguishing feature

[edit] Similar Species

Great Northern Diver differs among other is a different shape to the bill, more symmetrical in the both upper and lower mandible tapers to the tip.

[edit] Distribution

[edit] Breeding

In North America breeds in northern Alaska and north-central Canada including many of the Arctic islands. In Eurasia breeds on the Arctic coast but range little-known. Has bred on Novaya Zemlya but main range lies to the east. May have bred further west in the Varanger area of Norway, on the Kola Peninsula and on Ostrov Kolguyev.

[edit] Non-breeding

Winters in Pacific in small numbers off Kamchatka and northern Japan and in varying numbers on the coast of North America from southern Alaska to California, vagrant to Baja California. Accidental vagrant in interior and eastern North America.

Rare in Europe but small numbers occur from southern Norway to the White Sea, off northern Scotland and on passage in the Baltic.

Vagrants recorded south to Spain and Italy.

[edit] Taxonomy

This is a monotypic species.

[edit] Habitat

Breeds on tundra lakes but coastal on passage and in winter.

[edit] Behaviour

[edit] Breeding

Begins late June-July and nests beside water often on an island or spit. Nest is a shallow scrape beside water or rarely a more substantial mound of vegetation.

Eggs: 2 (1 in replacement clutch), olive-brown, paler than Great Northern, with sparse black blotches (89 x 56mm). Incubated by both sexes for 29-30 days. Young tended by both sexes, feed themselves at 40 days and fly at about 72 days

[edit] Diet

Fish, also molluscs and crustaceans caught during 60-120 second dives.

[edit] Vocalisation

Resembles Great Northern Diver but louder and harsher.

[edit] External Links