 Polar bear sex. It's surprisingly lovely - gentle, cosy, fluffy, touching even. Until this other fella polar bear turns up, sniffing around, wanting a piece of the action. after a little scuffle, he's sent packing.  another male arrives, a bigger one, enormous when standing. There's a proper heavyweight fight this time. Terrifying, it's hard not to think of that poor boy a few weeks back. This second one is defeated too, but now our original hero, Mr Lover Lover Polar Bear, is bloodied and torn. Heroic though, surely Mrs Polar Bear will reward him most generously . . . No, she's not interested. Bored waiting, she's gone off the whole idea. Women! They're a mystery. and that seems to include lady polar bears. Still, I imagine that in a later episode of Frozen Planet (BBC1) we'll see adorable little polar bear cubs tumbling out of a hole in the snow.  Winter is ending, the pack ice is melting, shearwaters are arriving by the million, the sea is boiling with birds and whales and krill. Boiling with life. Over in Greenland, a sapphire-blue melt lake forms, spill water runs off, carving its way along channels, until suddenly it reaches a big hole and plunges vertically down into the ice. How am I supposed to feel about this? I wouldn't know if it wasn't for the music, which after crescendoing along the channels, now reaches a big swirling orchestral climax. This is obviously something profound, so I am moved.  Somewhere else a beautiful Harry Potter owl hunts in the snow. and in the tundra a gang of asbo wolves harasses some bison, hoping to separate one off for tea. They give chase, accompanied by chase music. The bison don't come out of this well; they are stupid and cowardly, one even helps the wolves by taking out one of its own young, runs it over. The wolves tuck in. Mmmm, bison. It's both thrilling and sad - though not as thrilling, or as sad, as the Weddell seal later on in the antarctic. arrr, did you see his poor sad whiskered face, exhausted and resigned, as he was finally pulled backwards by the tail off his tiny ice floe and into the jaws of the killer whales that had hunted him down?  To be honest, I'm not sure I'm learning much. It's dark in the winter, for a long time. Cold, obviously, flipping freezing. Harsh as hell. But rich in life, and important, to everything. I think I knew most of that. That you get polar bears at the top and penguins at the bottom. and that, though it's mainly white around these parts, it's red in tooth and 