Winter

The fifth instalment is set in the polar winter: the polar regions are scourged by extreme cold and strong winds. The snow spreads into the subarctic regions such as the taiga forests of the Northern Hemisphere. Animals highlighted in this episode include the polar bear, the spectacled eider (Somateria fischeri), the common eider, the gray wolf hunting for American bison, the wolverine (Gulo gulo), the common raven (Corvus corax), an unspecified vole (subfamily Arvicolinae) hunted by both the great grey owl and the least weasel (Mustela nivalis), the emperor penguin, the Weddell seal, the bald notothen (Pagothenia borchgrevinki, called "Borchgrevinki fish" by David Attenborough), and the Adélie penguin.