The Best Of Polar Bears | BBC Earth

The Arctic. Millions of square kilometres of empty ice. Polar bears are normally solitary. You might think that just finding a partner in this desolate landscape would be the challenge. But they have an excellent sense of smell and can detect another bear from over the horizon. Male bears can spend weeks tracking the scent of a female who's ready to mate. They sniff closely to size each other up. She'll raise her cubs alone, devoting herself to them for two, even three years. It's a huge commitment of time and effort. So it's vital to pick a male who will provide strong and healthy genes for her offspring. It looks as though she's going to put this potential suitor through his paces. She leads him up and down the slopes. It's as if she's testing his fitness. They start to play. Courtship is one of the few times that adult animals play together. This slope is rather steep for the heavier male. It's no good. He can't quite manage it. But she seems to have decided that he might be the one. Whilst he seems to have lost interest. It's her turn to do the chasing. And she's got a few tricks up her sleeve. That was enough to entice him up again. They're all safely ashore. But they could still face months of hunger. Finding food is not so easy on this cold and barren coast. The search may be a long one. Polar bears have an extraordinarily sensitive sense of smell. And she has caught a faint whiff of something promising. It's the immense carcass of a bowhead whale. A whale carcass could provide more than any one family could eat. But they're not the first here to find it. By any means. The smell has brought in bears from miles away. Bear families seldom get on with one another. She's taking a risk bringing her cubs here. Male bears can and do kill and eat small cubs. Another family challenges her. She must decide whether to compete for food or run away and go hungry. She keeps her cubs close to her and stands her ground. Their mother's courage has won the cubs a meal. Exhausted from his swim, the bear must regain his strength. The next day, a sea fog shrouds the island. The walruses sense that they're in danger. Using the fog as cover, the bear approaches the herd. The adults close ranks around their young, presenting a wall of blubber and hide. He tests the barrier, but it stands firm. It appears that the world's largest land carnivore has met his match. There must be a chink in the armour somewhere. Not here. This female walrus is shielding her pup if he can just prise her off. The bear's claws and teeth can't penetrate her thick hide. With the herd retreating to water, the bear must move quickly. Having failed with one, he heads straight for another. The chance of his first meal in months is slipping away. He seems increasingly desperate. It's now or never. He must avoid the stabbing tusks if he's to win. The flailing walrus is immensely powerful and drags the bear away from the shallows towards the safety of the herd. It slips from his grasp. It's March, and light returns to the high Arctic, sweeping away four months of darkness. A polar bear stirs. She has been in her den the whole winter. Her emergence marks the beginning of spring. After months of confinement underground, she toboggans down the slope, perhaps to clean her fur, perhaps for sheer joy. Her cubs gaze out at their bright new world for the very first time. The female calls them, but this steep slope is not the easiest place to take your first steps. But they are hungry and eager to reach their mother, who's delayed feeding them on this special day. Now she lures them with the promise of milk, the only food the cubs have known since they were born, deaf and blind beneath the snow some two months ago. Their mother has not eaten for five months and has lost half her body weight. Now she converts the last of her fat reserves into milk for her cubs. The spring sun brings warmth, but also a problem for the mother. It starts to melt the sea ice. That is where she hunts for the seal she needs to feed her cubs, and she must get there before the ice breaks up. For now, though, it's still minus 30 degrees and the cubs must have the shelter of the den. At this time of year, polar bears, on average, succeed only once in 20 hunts. If the hunter is skinny, like this one, that may not be often enough. All she can do is keep trying. To prevent her scent betraying her, she makes a wide sweep to get downwind of the seal. Getting close. She's now right behind the seal. Incredibly, she caught the seal underwater. It's only small, but even so, its blubber alone will contain 100,000 calories, enough to sustain this bear for a week. And in that time, she might even catch another. But this can't go on forever. As summer continues, temperatures are rising. Each hunt requires more energy, draining the bears of their reserves. I'm really hoping Lyra and Mickey will have returned. And we're in luck. Our family is back, but Lyra's behaviour is different. It's interesting. She's coming towards us. There she goes. OK, Lyra is closer. This is when I start getting nervous. Just a bit. OK, Lyra, I can see that you're smelling the air. And I'm just a little bit worried that it's the smell that's coming from me that's holding your attention. This is not a bear that is at all scared. It's a bear that's figuring out what's going on, whether there is an opportunity to feed here. We're completely downwind, so Mickey's getting quite a good scent of us here. Lyra's always actually moved away from us and kept a personal distance. And right at the moment, it's the first time in the last year of being with her that she's actually turned around and come towards us. Her body movement and her stance worries me a little bit when she's tense. She basically puts her front paws forward and builds up a stance. It's like a spring ready to take off. When they come at you, their initial speed is incredibly fast. This is the first time I've felt threatened by Lyra. If she comes, you drop everything. You drop the monitor, you drop the camera. Jason? Is he safe there? I'll just grab one more shot of Lyra. I don't like it. OK, shall we move back, then? If you don't like it, I'd rather move back now. Please. Gordon? OK. Right, Lyra, that's close enough for now. Despite the fact that she hasn't been aggressive towards us at all, there may well come a point where she views me differently, that she sees me and thinks, possibly, this is something that I can eat. Maybe this is my next meal. We may be safe, but I'm so worried about Lyra and Mickey.