As winter finally passes, ice sheets rapidly begin to melt. For polar bears, this is a moment of jeopardy, but for others like the arctic fox, beluga whales, and lemmings, this brief summer transforms the Arctic into the richest place on Earth.

The temperate rainforest of British Columbia is home to the last big carnivores of North America- the great grizzly bear and forest wolf, drawn together into deadly conflict once a year as the rivers teem with spawning salmon.

Following the annual rains, the parched grassland of the Serengeti plain flushes green and draws in the greatest concentration of large animals on the planet. Over two million wildebeest, zebra, and gazelle have undergone an epic journey to graze.

Winter in South Africa's east coast, draws billions of sardines northwards from the Cape to feed on the plankton-rich soup. The Sardine Run is the greatest marine spectacle on the planet, attracting an awe inspiring cast of ocean predators.

In the intense heat of the northern Kalahari, the dramatic annual flooding of Botswana's Okavango Delta turns 6,000 square miles of desert into a maze of lagoons, islands and swamps. Millions of animals are drawn to the oasis.

The arrival of spring triggers an explosion of life in Alaska's coastal waters so great that it eclipses even the Amazon rainforest. The feast draws in an amazing cast of characters, including humpback whales from Hawaii and resident sea lions.