-  It’s National Walk to Work Day  (© David Tipling Photo Library/Alamy)

Every year approximately 4,000 pairs of emperor penguins trudge across the frozen landscape to reach Snow Hill Island, turning this snow-capped island off the east coast of the Antarctic Peninsula into a crowded breeding colony. While there, the male penguin’s job is to carefully guard the egg his mate has laid, and make sure it stays sufficiently warm enough for the chick inside to hatch.