Unlike other loons/divers, this bird may migrate in flocks. It winters at sea, mainly on the Pacific coast, or on large lakes over a much wider range, including China, Japan, North Korea, South Korea, USA and Mexico. It has occurred as a vagrant to Greenland, Hong Kong, Great Britain, Spain, and Finland.[[|]]
Breeding adults are like a smaller sleeker version of Great Northern Diver/Common Loon. They measure 58–74 cm (23–29 in) in length, 110–128 cm (43–50 in) in wingspan and weigh 1–2.5 kg (2.2–5.5 lb).[[|]] They have a grey head, black throat, white underparts and chequered black-and-white mantle. Non-breeding plumage is drabber with the chin and foreneck white. Its bill is grey or whitish and dagger-shaped. In all plumages, lack of a white flank patch distinguishes this species from the otherwise very similar Black-throated Diver/Arctic Loon.This species, like all divers/loons, is a specialist fish-eater, catching its prey underwater. It flies with neck outstretched.The call is a yodelling high-pitched wailing, as well as harsh growls and bark.