A darker cousin of MALL. Scarce in most areas, though locally common in saltwater marshes where can form sizeable flocks in winter. Declining, largely due to encroachment from MALL with which it frequently hybridizes. Working out which are ‘pure’ birds is difficult. Very wary and easily flushed. Usually doesn’t mix with other species, other than MALL! ID: Size and shape as MALL. In flight bold whitish underwing contrasts strongly with rest of bird. Purple/dark blue speculum bordered by black with narrow or no trailing white edge to secondaries (compare MALL). Male darkest with strong head and neck contrast. Dark cap shows green iridescence when seen well but extent of Mallard influence is unknown. Bill yellow with black nail. Female paler with duller green bill. Hybrids: true status unknown because of similarity of backcrosses to purebreds. Many hybrids have intermediate characters, notably half a green head and obvious white borders to speculum; others show far more subtle differences.