Pascal Pittorino / Corsican pig (Sus scrofa domestica) sow, suckling the piglets, Parc Naturel Regional de Corse / Natural Regional Park of Corsica, Corsica Island, France. September.

Steven Kazlowski / Polar bear (Ursus maritimus) sow with two juveniles walk along the ice edge during autumn freeze up, Beaufort Sea, off Arctic coast, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) sow walking on a barrier island during autumn freeze up, Bernard Spit, North Slope, Arctic coast of Alaska, September

Steven Kazlowski / Polar bear (Ursus maritimus) sow with a pair of cubs walk on a barrier island during autumn freeze up, Bernard Spit, North Slope, Arctic coast of Alaska, September

Steven Kazlowski / Polar bear (Ursus maritimus) sow with a pair of cubs walk on a barrier island during autumn freeze up, Bernard Spit, North Slope, Arctic coast of Alaska, September

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) portrait, female. Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska.

Steven Kazlowski / Spirit bear (Ursus americanus) sow with dark cub walking on a log at high tide, along the coastal rainforest of the central British Columbia coast, Canada

Steven Kazlowski / Polar bear (Ursus maritimus) sow and cub sliding on their backs over the pack ice, much like ice skating, 1002 coastal plain of the Arctic National Wildlife Refuge, Alaska, USA

Nick Turner / Gloucester old spot piglets (Sus scrofa domestica) suckling at the Cotswold Farm Show, Cirencester, UK, July 2008.

Steven Kazlowski / Polar bear (Ursus maritimus) curious cub stands along Bernard Spit as its mother and other cub rest in the background, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Florian Möllers / Wild boar (Sus scrofa) sow and piglets foraging in a city garden, Argentinischen Allee, Berlin, Germany, March 2007

Ernie Janes / Domestic pig, free range sow and piglet sniffing noses, UK, August 2010