The Scaly-sided or Chinese Merganser breeds in the Russian Far East, northern China and North Korea and spends winter in southern China, South Korea, Taiwan and Japan.
It is highly endangered by deforestation, pollution, hunting, being out-competed by its relative the Goosander and predated by introduced species such as mink.
Above is a male in transition to eclipse plumage. He has a black back rather than the female's grey but his head has already turned to the brown of the female rather than
his breeding plumage of iridescent green-black. The scientific name "squamatus" refers to the pattern of reptilian scales on its sides. The female has soft grey scale patterns.
Like other mergansers, it mainly dives underwater to feed.