In the foreground of the illustration are the male and female, and in the background two males are in courtship display. Gould described the males as depicted in one of their 'outre positions... when the head is thrown back on the lower part of the back, with the bill at a right-angle to the body, an attitude which is repeatedly assumed as the males approach each other, or slowly pirouette...in circles round the female.'

Gould enjoyed watching 'the stately-swimming old Drakes, with their large green heads and full golden-coloured eye through an opera glass.'. Prism binoculars were patented in 1859 but this (1869) is the first reference to Gould using them.

DISTRIBUTION: Breeds throughout Holarctic between about 66°N and 46°N. Winters south to Mediterranean sea, Iran, southeast China, Japan and in North America south to southern United States. In Britain a breeding population established in 1970 in Invernesshire had at least 95 occupied nests in 1990