Mike Potts / New Zealand scaup (Aythya novaeseelandiae) on Lake Wanaka, South Island, New Zealand.

Andy Trowbridge / New Zealand Scaup (Aythya novaeseelandiae) in flight. Lake Forsyth, Banks Peninsula, Christchurch, New Zealand. July.

Andy Trowbridge / New Zealand Scaup (Aythya novaeseelandiae) in water, late evening light. Christchurch, New Zealand. July.

Andy Trowbridge / New Zealand scaup (Aythya novaeseelandiae) bathing. Christchurch, South Island, New Zealand. July.

Graham Eaton / Lesser Scaup (Aythya affinis) captive, Martin Mere Wildfowl and Wetlands Trust. Lancashire, UK. December.

Markus Varesvuo / Scaup (Aythya marila) males, Iceland June

Brent Stephenson / Adult female New Zealand scaup (Aythya novaeseelandiae) swimming across the surface of a pond. Waikanae Estuary, Wellington, New Zealand, August.

Brent Stephenson / Adult male New Zealand scaup (Aythya novaeseelandiae) flapping its wings. Lake Rotorua, Bay of Plenty, New Zealand, July.

Steve Gettle / Greater Scaup (Aythya marila) male in breeding plumage, Saginaw Bay, Michigan

Andrew Walmsley / New Zealand scaup duck (Aythya novaeseelandiae) on water, Travis Wetland Reserve, Christchurch, South Island, New Zealand, July

Roger Powell / Greater scaup (Aythya marila) two pairs, males on left, on lake against emerging reedbed, Kongsfjordfjellet, Finnmark, Norway. June.

Roger Powell / Greater scaup (Aythya marila) pair, male on right, on icy lake, Kongsfjordfjellet, Finnmark, Norway. June.