Will This Caribou Herd Survive? | Nature's Great Migrations | BBC Earth

With just 10 days left to calving, time is against them. Taking the mountain route will add miles to the journey, causing a potentially disastrous delay. It would also bring them into contact with more predators. Just ahead, a bear is on the prowl. Despite the strong currents, the herd is forced to cross the river. The lead female enters the water and the others follow. This could be a catastrophic mistake. The force of the meltwater has created a powerful set of rapids. But the caribou forge ahead regardless. The lead animals are struggling to make progress and are regularly sucked under by the powerful eddies. The rapids are overwhelming. Before long, the rest of the caribou have beaten a retreat. With nowhere left to turn, they opt for the mountain route. But that means heading directly towards a bear. And he isn't alone. A wolf slips through the trees below the caribou. Perhaps sensing the danger, they change course again, returning to the river further upstream. And from here, there's only one option. At this point, the river is slightly shallower than the first spot they tried, but the current is still strong. The older females in the group lead the way again. Suddenly, a yearling drifts away from its mother. Even some of the adults are struggling. The yearling is out of its depth, on its own and heading towards the rapids. But she has one thing on her side. Caribou fur is hollow to help insulate against the cold, which means she can float. It's been a close call, but the break-off group have successfully rejoined the herd.