Pete Oxford / Close up of Snow Goose (Chen caerulescens) with head tucked into wing, Slimbridge Wildfowl and Wetlands Trust, SW England, UK captive

Ann & Steve Toon / Common / Eurasian cranes (Grus grus) immature bird standing by water in enclosure, Great Crane captive breeding and reintroduction project, Wildfowl and Wetlands Trust, Slimbridge, Gloucestershire, UK...

Ann & Steve Toon / Common / Eurasian cranes (Grus grus) immature birds being taught to fed by researchers performing the role of 'crane mother', Great Crane captive breeding and reintroduction project, Wildfowl and Wetl...

Ann & Steve Toon / close up of feeder designed to look like adult Common / Eurasian crane (Grus grus), Great Crane captive breeding and reintroduction project, Wildfowl and Wetlands Trust, Slimbridge, Gloucestershire, U...

Ann & Steve Toon / Common / Eurasian crane (Grus grus) two chicks with 'crane mother', Great Crane captive breeding and reintroduction project, Wildfowl and Wetlands Trust, Slimbridge, Gloucestershire, UK, May 2011. Mod...

Ann & Steve Toon / Common / Eurasian crane chick (Grus grus) being exercised by 'crane mother' in crane costume, Great Crane captive breeding and reintroduction project, Wildfowl and Wetlands Trust, Slimbridge, Gloucest...

Ann & Steve Toon / Common / Eurasian crane chick (Grus grus) at Wildfowl and Wetlands Trust, Great Crane captive breeding and reintroduction project, Slimbridge, Gloucestershire, UK, May 2011.

Ann & Steve Toon / Common / Eurasian crane chick (Grus grus) being fed with artifical feeder, Great Crane captive breeding and reintroduction project, Wildfowl and Wetlands Trust, Slimbridge, Gloucestershire, UK, May 20...

David Woodfall / Greater flamingos (Phoenicopterus roseus) at Slimbridge Wildfowl and Wetlands Trust.

David Woodfall / Greater flamingos (Phoenicopterus roseus) at Slimbridge Wildfowl and Wetlands Trust, Gloucestershire, UK

David Woodfall / Mute swans (cygnus olor) in front of Slimbridge Wildfowl and Wetlands Trust, Gloucestershire, England, November

David Woodfall / Greylag geese (anser anser) feeding at Slimbridge Wildfowl and Wetlands Trust, Gloucestershire, England, UK