Edwin Giesbers / Five Mallard (Anas platyrhynchos) walking in a line across snow. Three males and two females. The Netherlands, January.

Charlie Summers / Burchell's Zebra (Equus quagga burchellii) herd walking towards waterhole in the late afternoon, kicking up dust as they come. Etosha National Park, Namibia, Southern Africa

Ernie Janes / Aylesbury ducks following in a line on village green, Weedon, Buckinghamshire, UK, October

Jerry Monkman / Rows of organic Cabbage plants (Brassica oleracea capitata) growing at the Harlow Farm in Westminster, Connecticut River Valley, Vermont, USA. August 2007

Steven Kazlowski / Polar bears (Ursus maritimus) female with cubs aged two years travelling along a barrier island during autumn freeze up, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, Alaska

Christian Ziegler / Red-eyed Tree Frog (Agalychnis callidryas) three males sitting on a stem, Soberania National Park, Panama

Konrad Wothe / Barn Swallow (Hirundo rustica) chicks lined up in nest with their mouths open waiting for food, Germany

Mitsuhiko Imamori / Honeypot Ant (Camponotus inflatus) repletes hanging from ceiling of larder, engorged with nectar they will regurgitate on demand to other workers, central Australia

Mitsuhiko Imamori / Honeypot Ant (Camponotus inflatus) repletes hanging from ceiling of larder, engorged with nectar they will regurgitate on demand to other workers, central Australia

Bence Mate / Silhouette of an African leopard (Panthera pardus pardus) snarling, Mkuze, South Africa. September. 'White Fang' - this leopard bared its fangs to the hyenas threatening his prey. Eventually the leopa...

Heike Odermatt / Walrus (Odobenus rosmarus) wet skin, Svalbard, Norway

Oliver Wright / Four-spotted chaser (Libellula quadrimaculata), close up of thorax, abdomen and wings, covered in early morning dew. Skipwith Common National Nature Reserve, North Yorkshire, England, UK. May. Focus s...