FREEZE! You’re on camera

They might look like Muppet babies, but these gorgeous grey-headed albatross chicks on the island of South Georgia in the South Atlantic are gravely endangered – and their fate is an unexpected result of climate change. To keep their eggs off the freezing ground, the adults build these chimney-pot nests, but the worsening storms in the South Atlantic, with winds now frequently gusting at hurricane force, are blowing the chicks off them. When this happens, the adults are unable to recognise their own babies – it seems evolution has programmed them to know their chicks only when the bundles of feathery fluff are in their right place.

‘This must be a new problem,’ says Fredi Devas, who produced the Antarctic episode of Seven Worlds. ‘The birds haven’t had time to evolve an effective response, so a lot of the chicks freeze to death in the icy mud. It’s tragic – and it’s reduced albatross numbers on South Georgia by more than half in 15 years.’

Also on South Georgia the team filmed bull elephant seals, the largest seal in the world which can be almost 7m long and weigh up to five tonnes – five times the weight of a small car – fighting to settle mating rights. They rear up and slam their bodies together, but these epic battles don’t interest the 500,000 king pengu ns, colony stretches from the beach to the mountain peak around St Andrews Bay. The penguins are more concerned with feeding their chicks, so they must trot back and forth to the sea to get fish dinners.

But the biggest fish dinner around here is gobbled up by hundreds of immense fin whales, the most ever filmed at one time. Once on the verge of extinction, heir numbers – along with hose of other whales – ave surged back thanks to lobal conservation efforts. in whales are twice the ize of humpbacks, yet hey feed on some of the cean’s smallest creatures: rill, a tiny shrimp.

Robot drones capture ing pictures of the whales feasting for the show, but technology was little use to the brave divers who had to drop down 9ft wide holes in the ice shelf to film the seabed below the frozen surface. Their GPS trackers didn’t work under such thick ice, so they had to find their way back to the holes by memory before their air supply – with enough oxygen for just 20 minutes – ran out.

lbatross chicks in their ests, and (left) bull lephant seals fighting

Some populations of the southern right whale – so called because its inquisitive nature made it easy to harpoon and when it died it floated, making it the ‘right’ whale to catch – have doubled in the past decade