A polar bear mother keeps watch over her cub as they wait for the coming winter and the plentiful feeding opportunities it brings. But there are threats abound: from cannibalistic male bears, to the devastating impact of climate change, which has delayed the seasonal freeze and put them at risk of starvation.

Every year, thousands of salmon make their way upstream along the nearly 2000-mile-long mighty Yukon River, desperate to reach spawning beds. Eagerly checking their progress is a host of hungry predators, from grizzly bears to bald eagles--all desperate to stock up on protein before the long winter months ahead.

Every summer, the frozen waters of Hudson Bay partially thaw for a few short months. For migrating beluga whales, it's a seasonal window of feeding and breeding opportunities, but for polar bears, it's a famine-filled test of their survival. Explore the shifting fortunes of a vibrant Arctic world.