0:00:44 > 0:00:49The Islands of Svalbard in Arctic Norway.
0:00:49 > 0:00:53They might be remote, but they're under surveillance.
0:00:55 > 0:00:57WHIRRING
0:01:02 > 0:01:04Spy cameras are capturing
0:01:04 > 0:01:08the most intimate images ever taken of polar bears.
0:01:08 > 0:01:13They're revealing some remarkable behaviour, and discovering an animal
0:01:13 > 0:01:17of surprising curiosity and intelligence.
0:01:25 > 0:01:28Snowcam doesn't operate alone.
0:01:33 > 0:01:36Blizzardcam can travel at 40 mph,
0:01:36 > 0:01:40powered by propellers and gliding on skis.
0:01:43 > 0:01:46Snowballcam can operate at temperatures of 40 below.
0:01:46 > 0:01:50Its spherical design makes it almost indestructible.
0:01:55 > 0:02:00Together they explore the islands, looking for bears.
0:02:02 > 0:02:05Their first mission is to film a mother with cubs
0:02:05 > 0:02:08emerging from maternity dens hidden in these hills.
0:02:08 > 0:02:14The only clue to the den's presence is a snowy mound.
0:02:14 > 0:02:18Driftcam and other spycams can lay in wait for days.
0:02:24 > 0:02:28They're left unattended, primed to film the moment they sense movement.
0:02:31 > 0:02:35A whiteout soon makes their task seem like mission impossible.
0:02:41 > 0:02:44But help is a paw swipe away.
0:03:08 > 0:03:11The cub's first steps outside the den...
0:03:11 > 0:03:13filmed by his mother.
0:03:38 > 0:03:42She pushes the camera down the slope.
0:03:42 > 0:03:43A tracking shot!
0:03:50 > 0:03:54As she films, there is no human presence of any kind.
0:04:08 > 0:04:11She even adjusts the camera to record her own exit.
0:04:32 > 0:04:36She must get her cub to the sea-ice before it breaks up and thaws,
0:04:36 > 0:04:39otherwise they'll be trapped on the island for the summer,
0:04:39 > 0:04:41with little to eat.
0:04:45 > 0:04:48She needs to be careful.
0:04:49 > 0:04:52Males roam the ice-fields below,
0:04:52 > 0:04:54and they kill cubs.
0:04:59 > 0:05:05They will try to mate with the mother so she has their cubs instead.
0:05:08 > 0:05:12But the larger males find deep snow and steep slopes heavy-going.
0:05:12 > 0:05:15She wisely keeps her cub to the higher ground.
0:05:25 > 0:05:28Back at the den-sites, other cubs are yet to emerge.
0:05:32 > 0:05:36They appear over a five-week period from March to April.
0:05:36 > 0:05:40After ten days of waiting, something stirs.
0:05:50 > 0:05:54The mother has waited six whole months for this moment.
0:06:00 > 0:06:02She blinks in the sunlight.
0:06:02 > 0:06:04She spent her confinement in semi-darkness.
0:06:11 > 0:06:16She checks that the coast is clear, and then reveals her secrets.
0:06:31 > 0:06:32Time for a stretch.
0:06:32 > 0:06:37She's been cooped up with her cubs since she gave birth three months ago.
0:06:52 > 0:06:53They learn by example,
0:06:53 > 0:06:56but their first lesson seems to be about snowballs.
0:07:14 > 0:07:18When she leaves, she expects them to follow.
0:07:24 > 0:07:28But the first steps are always the most difficult to take.
0:07:32 > 0:07:36He will soon learn that to survive they must stick together.
0:07:50 > 0:07:52A frozen sea now surrounds the islands.
0:07:52 > 0:07:55It stretches all the way to the North Pole.
0:07:55 > 0:07:59It is out on this ice that most polar bears spend their lives.
0:08:07 > 0:08:11But in spring males return to land to search for females.
0:08:19 > 0:08:23Males may be a risk to cubs, but this one is otherwise engaged.
0:08:23 > 0:08:26He's found a lone female.
0:08:34 > 0:08:38But polar bear courtship is never straightforward.
0:08:38 > 0:08:40She likes to play hard to get.
0:08:42 > 0:08:45It's also a challenge for blizzardcam.
0:09:02 > 0:09:05She's testing his fitness, making sure he's a good catch.
0:09:13 > 0:09:16His skills on the slopes show room for improvement.
0:09:30 > 0:09:35And now the female invents a new challenge - a climbing contest.
0:09:38 > 0:09:41Her huge claws act like crampons.
0:09:41 > 0:09:45Being lighter and nimbler, she has the advantage.
0:09:47 > 0:09:51Males can be twice as heavy, reaching three quarters of a ton.
0:09:55 > 0:09:58HE GROANS
0:09:58 > 0:10:05She's after a mate that's playful and energetic,
0:10:05 > 0:10:08one with strong genes.
0:10:10 > 0:10:14But his chances are slipping away.
0:10:15 > 0:10:19She tested his performance and pushed him too far.
0:10:28 > 0:10:32Meanwhile, the mother with one cub is still sticking to higher ground.
0:10:37 > 0:10:40But deep snow is a real struggle for her little cub.
0:10:52 > 0:10:55SHE CALLS
0:10:59 > 0:11:02She encourages him with reassuring calls.
0:11:21 > 0:11:24She's aware of his difficulties and uses her body as a shield.
0:11:29 > 0:11:30She must stay attentive
0:11:30 > 0:11:34if her cub is to survive in this harsh Arctic world.
0:11:41 > 0:11:45Realising he's exhausted, she digs a hollow to rest in.
0:11:45 > 0:11:49In day-dens like this she suckles him six times a day.
0:12:02 > 0:12:07Meanwhile, the courting male is yet to prove he's up for the job.
0:12:09 > 0:12:12But the female doesn't like being ignored.
0:12:15 > 0:12:18She tries to reignite his passion.
0:12:31 > 0:12:33Time to turn up the heat.
0:12:59 > 0:13:01He's certainly interested now.
0:13:06 > 0:13:08She's falling head over heels for him.
0:13:22 > 0:13:24He's now totally captivated.
0:13:27 > 0:13:30But still she gives him the runaround.
0:13:36 > 0:13:40But in courtship there are always casualties.
0:13:45 > 0:13:48Blizzardcam is at the bear's mercy.
0:13:56 > 0:14:00But again a bear helps with the filming.
0:14:05 > 0:14:06Sealed with a kiss,
0:14:06 > 0:14:10the couple's whirlwind romance will last three weeks.
0:14:20 > 0:14:24Out on the frozen sea, a young male has killed a seal.
0:14:29 > 0:14:34He caught it when it surfaced through a breathing hole in the ice.
0:14:34 > 0:14:39To film from a different angle, blizzardcam deploys snowballcam.
0:14:44 > 0:14:49This technical miracle rolls with no visible moving parts.
0:14:49 > 0:14:52Its lens even boasts a self-righting mechanism.
0:14:59 > 0:15:02A close-up reveals that he's eating the blubber.
0:15:02 > 0:15:06This provides the most nutrition and is always eaten first.
0:15:11 > 0:15:14Seals make up 95% of a polar bear's diet
0:15:14 > 0:15:17and are only found near the sea-ice.
0:15:21 > 0:15:27The two-cub family are attracted to the frozen sea to hunt seals as well.
0:15:29 > 0:15:34She hunts the pups of ringed seals that hide in snowy dens on the ice.
0:15:36 > 0:15:40She finds them by smell, even a metre down.
0:15:41 > 0:15:46She pile-drives the snow with a force of two tons,
0:15:46 > 0:15:48but the roof of the den holds.
0:15:58 > 0:16:00Back at the carcass,
0:16:00 > 0:16:04the spycams stay on to film bears attracted to the leftovers.
0:16:09 > 0:16:11The mother and single cub.
0:16:11 > 0:16:14She could smell the remains from 20 miles away.
0:16:18 > 0:16:21In the den, she spent six months without eating
0:16:21 > 0:16:23while the males fattened up on seals.
0:16:31 > 0:16:33She leaves little behind.
0:16:39 > 0:16:42Males are still on the lookout for females.
0:16:47 > 0:16:51For her cub's safety, she heads back to the hills.
0:16:56 > 0:16:59But, as spring continues,
0:16:59 > 0:17:02lengthening days bring sudden and dramatic change.
0:17:03 > 0:17:07The highest tides of the year combine with rising temperatures
0:17:07 > 0:17:11to trigger a vast breakup of the ice that surrounds the islands.
0:17:16 > 0:17:21In just one night it can crack apart and drift 20 miles or more.
0:17:45 > 0:17:48Svalbard is a series of islands once more.
0:17:56 > 0:18:00The mother and single cub are still on the snowy hills,
0:18:00 > 0:18:03but signs of change are all around.
0:18:17 > 0:18:20At the shoreline, things are not as expected.
0:18:28 > 0:18:30The sea-ice has drifted northwards
0:18:30 > 0:18:34and, with it, the bears' food supply.
0:18:34 > 0:18:37It's a huge swim for an adult bear.
0:18:37 > 0:18:41For the cub, it's out of the question.
0:18:43 > 0:18:47Their ship has sailed and left them behind.
0:18:47 > 0:18:50They are marooned on the island for the summer.
0:18:56 > 0:18:59The two-cub family managed to board the sea ice
0:18:59 > 0:19:01before it drifted too far.
0:19:01 > 0:19:07This new and ever-changing world requires a different spy camera.
0:19:07 > 0:19:09Icebergcam.
0:19:11 > 0:19:14It effortlessly steers between ice sheets
0:19:14 > 0:19:17and its turret rotates to follows the bears.
0:19:40 > 0:19:43The bears' lives are now governed by the state of the drifting ice
0:19:43 > 0:19:46and the movement of the seals.
0:19:55 > 0:19:59The cubs are expected to keep up but their mother knows their limits,
0:19:59 > 0:20:02avoiding long, hazardous swims.
0:20:40 > 0:20:43But all the while she keeps them on the move,
0:20:43 > 0:20:46tracking the seals that gather around the leading edge of ice.
0:20:52 > 0:20:56Back on land, icebergcam follows the one-cub family.
0:21:00 > 0:21:04With the seals gone, beachcombing is her best option to find food.
0:21:07 > 0:21:09He practises his climbing skills...
0:21:10 > 0:21:12..but it's early days.
0:21:14 > 0:21:17She has found something just below the surface.
0:21:29 > 0:21:32She checks how deep she has to dive,
0:21:32 > 0:21:35then takes the plunge.
0:21:42 > 0:21:45It's seaweed.
0:21:46 > 0:21:48Kelp is not wildly exciting,
0:21:48 > 0:21:52but it does contain carbohydrates and some protein too.
0:22:00 > 0:22:04The cub must find her acrobatics rather strange.
0:22:25 > 0:22:28Hungry bears eat virtually anything.
0:22:28 > 0:22:31It's a question of making the most of what's around.
0:22:31 > 0:22:35And it's never too soon to start hunting.
0:22:55 > 0:23:00Polar bears investigate every unfamiliar sight and smell.
0:23:00 > 0:23:04They are the most curious subjects ever filmed by spycams.
0:23:13 > 0:23:17This fascination suggests a surprising intelligence,
0:23:17 > 0:23:21one that evolved for the extraordinary challenges
0:23:21 > 0:23:22of hunting on ice.
0:23:29 > 0:23:32Ice floes present real difficulties for a predator,
0:23:32 > 0:23:35continually changing their shape and form.
0:23:40 > 0:23:42Seals are also tricky prey.
0:23:42 > 0:23:46In open water they are just too agile to catch.
0:23:53 > 0:23:57It becomes a little easier when they haul out on ice.
0:24:00 > 0:24:04But they hug the water's edge for a quick escape.
0:24:13 > 0:24:15The bear immediately has a problem.
0:24:15 > 0:24:18There is no cover between him and his prey.
0:24:21 > 0:24:26He wrong-foots the seal by seemingly walking away.
0:24:26 > 0:24:30Every hunt presents a different challenge,
0:24:30 > 0:24:33so he plans a new strategy each time.
0:24:33 > 0:24:34He slinks into the water,
0:24:34 > 0:24:38using a channel between the ice floes to act as cover.
0:24:52 > 0:24:55He swims, hardly making a sound,
0:24:55 > 0:24:59reaching six miles per hour at times.
0:25:00 > 0:25:04His front legs provide propulsion, while his back legs steer.
0:25:13 > 0:25:18His low profile makes him seem like a floating sliver of ice.
0:25:26 > 0:25:32He checks the seal's position and takes wind direction into account to work out his final approach.
0:25:37 > 0:25:39As he closes in he makes a clever move,
0:25:39 > 0:25:42diving deep beneath the ice floe.
0:25:50 > 0:25:53He emerges on the blind side of the seal.
0:26:07 > 0:26:10So far, so good.
0:26:19 > 0:26:22He can hold his breath for minutes,
0:26:22 > 0:26:25and calculate the seal's exact position.
0:26:35 > 0:26:38Slo-mo reveals just how close he got.
0:26:47 > 0:26:50His skills show a remarkable intelligence at work.
0:26:52 > 0:26:55He hunted in all three dimensions,
0:26:55 > 0:26:59making full use of the opportunities offered by water and ice.
0:27:04 > 0:27:06Back on Svalbard, it's high summer.
0:27:06 > 0:27:11Barnacle geese that had overwintered in Scotland have started to breed.
0:27:11 > 0:27:15Their calls bring hope to hungry bears.
0:27:23 > 0:27:28The cub stays back as his mother explores the possibilities.
0:27:32 > 0:27:35Bears have only recently discovered this new source of food,
0:27:35 > 0:27:40seeking out colonies that nest on the ground rather than on cliffs.
0:27:40 > 0:27:44The eggs are a rich source of protein.
0:27:44 > 0:27:48Just 250 are as nutritious as one ringed seal.
0:27:49 > 0:27:54She carefully picks up an egg in her jaws before swallowing its contents.
0:27:56 > 0:28:00The geese launch an attack.
0:28:04 > 0:28:08Some have goslings, a bite-size snack for a bear.
0:28:13 > 0:28:18In just one day, one bear can devour over 1,000 eggs and hatchlings,
0:28:18 > 0:28:21destroying a whole colony.
0:28:22 > 0:28:25But, as the threat escalates, so does the defence.
0:28:33 > 0:28:35Arctic skuas join the attack.
0:28:40 > 0:28:43A skua lands a direct hit.
0:28:43 > 0:28:44She's had enough.
0:28:47 > 0:28:50In future, the birds will have to start nesting on cliffs
0:28:50 > 0:28:51to avoid polar bear attacks.
0:28:54 > 0:28:57Skuas may have saved the colony this time
0:28:57 > 0:29:00but they've made the bears' lives a lot more difficult.
0:29:04 > 0:29:06Further north on Svalbard,
0:29:06 > 0:29:10other landlocked bears have found a more reliable meal,
0:29:10 > 0:29:14a carcass of a stranded fin whale.
0:29:15 > 0:29:19Icebergcam investigates the happy gathering.
0:29:20 > 0:29:24The whale is 24 metres long and weighs 60 tons,
0:29:24 > 0:29:28a once-in-a-lifetime feeding opportunity.
0:29:34 > 0:29:38An adolescent eats confidently alongside four adult bears.
0:29:44 > 0:29:46They continually chatter away to each other.
0:29:46 > 0:29:49It's all about keeping aggression under control.
0:29:49 > 0:29:51ROARING
0:30:01 > 0:30:06Their massive claws rake the skin like knives, cutting it into strips.
0:30:08 > 0:30:12At two years old, this bear is testing his status,
0:30:12 > 0:30:14standing up to other bears.
0:30:20 > 0:30:22Sharing food helps everyone survive
0:30:22 > 0:30:25in an environment where prey is usually hard to come by.
0:30:29 > 0:30:33As summer progresses, the temperature creeps above freezing
0:30:33 > 0:30:38and the larger ice sheets fragment into ever smaller plates.
0:30:39 > 0:30:43To avoid being trapped on shrinking ice floes,
0:30:43 > 0:30:47the cubs must get used to an endless polar assault course.
0:31:20 > 0:31:24Rolling is clearly fun, but it also has a purpose.
0:31:24 > 0:31:27It squeezes out water trapped in the fur.
0:31:37 > 0:31:41Her cubs are growing fast and are full of energy.
0:31:41 > 0:31:44But to keep them fit she must keep them fed.
0:31:46 > 0:31:49A male has killed a bearded seal.
0:32:03 > 0:32:07For the sake of her cubs, she needs to be cautious.
0:32:12 > 0:32:15Burying the carcass will help reduce its odour,
0:32:15 > 0:32:18concealing it from other bears.
0:32:25 > 0:32:28If it hasn't already been seen, that is.
0:32:36 > 0:32:39The bears at the whale carcass are in food heaven,
0:32:39 > 0:32:42but their peace is about to be shattered.
0:32:46 > 0:32:50This male heavyweight prefers to eat alone.
0:32:51 > 0:32:54He is bigger than the other bears
0:32:54 > 0:32:57and likes to throw his weight around.
0:32:58 > 0:33:00This is no time for heroics.
0:33:14 > 0:33:17The mother tries to guide her offspring away.
0:33:20 > 0:33:23But the young bear is an easy target.
0:33:43 > 0:33:46The male could kill with just one bite.
0:33:53 > 0:33:56The youngster daren't turn his back.
0:34:21 > 0:34:24But, despite the male's persistence,
0:34:24 > 0:34:27he seems to be just teaching the young upstart a lesson.
0:34:28 > 0:34:32Reunited with his mother, she appears to scold him.
0:34:32 > 0:34:34SHE BARKS
0:34:37 > 0:34:42Authority established, the male is now king of the carcass.
0:34:45 > 0:34:49Back at the kill site, the family finally steal a meal.
0:34:59 > 0:35:02This is a high-risk strategy.
0:35:07 > 0:35:12Like the male at the whale carcass, some bears don't do sharing.
0:35:18 > 0:35:21She stands up to make herself look bigger.
0:35:21 > 0:35:23The cub copies.
0:35:33 > 0:35:38Luckily this bear has no appetite for a fight.
0:35:59 > 0:36:02There is a feeding etiquette around a seal carcass.
0:36:02 > 0:36:06Bears that approach correctly are often allowed to share,
0:36:06 > 0:36:08particularly if they are known.
0:36:11 > 0:36:12They greet.
0:36:12 > 0:36:14Away from the carcass,
0:36:14 > 0:36:19young males often become friends, hanging out together.
0:36:23 > 0:36:28As ever, our spycams prove a huge hit with the curious bears.
0:36:40 > 0:36:42With the driftcams out of action,
0:36:42 > 0:36:44blizzardcam returns to frontline duties.
0:36:51 > 0:36:53And deploys back-up.
0:36:58 > 0:37:02Snowballcam's arrival fascinates the curious bears,
0:37:02 > 0:37:06particularly as the steep slope gives it momentum.
0:37:21 > 0:37:24He tries some fancy footwork.
0:37:25 > 0:37:27More bears join the team.
0:37:36 > 0:37:37Time for kick-off.
0:37:45 > 0:37:48It's polar bear football.
0:37:58 > 0:38:01Their ball control needs practice
0:38:01 > 0:38:03but they are experts at dribbling.
0:38:06 > 0:38:09The game descends into argument.
0:38:18 > 0:38:20The spycams return to the benches.
0:38:20 > 0:38:23The bears might be play-fighting, but things still get out of hand.
0:38:26 > 0:38:30Meanwhile, on Svalbard, a kittiwake colony brings hope
0:38:30 > 0:38:32to the hungry mother and cub.
0:38:37 > 0:38:41They can't reach the nests but there is still food to be had.
0:38:47 > 0:38:50Grass is the bears' emergency rations
0:38:50 > 0:38:54and it flourishes wherever bird droppings provide fertiliser.
0:39:04 > 0:39:09It provides little real nourishment but it helps stop hunger pangs.
0:39:09 > 0:39:12But, to survive, the bears will need protein.
0:39:16 > 0:39:19In comparison, the ice bears have it easy,
0:39:19 > 0:39:23but the rising summer temperatures can cramp a hunter's style.
0:39:31 > 0:39:34He's tracking bearded seals,
0:39:34 > 0:39:36an ambitious quarry.
0:39:39 > 0:39:43She has battle scars from a previous bear encounter.
0:39:43 > 0:39:45It won't be easy.
0:39:45 > 0:39:50The bear has two to choose from. The odds are good.
0:39:52 > 0:39:55But he's treading on thin ice.
0:40:00 > 0:40:05He spreads his legs to distribute his weight and progresses carefully.
0:40:14 > 0:40:17But it's not enough.
0:40:21 > 0:40:25For a hunting bear it doesn't get much worse than this.
0:40:28 > 0:40:31The seal could hardly fail to notice.
0:40:34 > 0:40:37But this battle-hardened seal is in no rush.
0:40:50 > 0:40:54Finally he gains some purchase. He's back in the game.
0:41:01 > 0:41:04He still believes he's in with a chance.
0:41:10 > 0:41:13He can charge at 25 miles per hour.
0:41:17 > 0:41:21But bears usually wait until they're 30 metres away.
0:41:21 > 0:41:23This one started at 300.
0:41:29 > 0:41:31She has all the time in the world to escape.
0:41:34 > 0:41:37Only the bears unexpected dunking in the ice
0:41:37 > 0:41:40could explain such an amateur performance.
0:41:47 > 0:41:52The ice is now so thin, it only supports the weight of the lighter cubs,
0:41:52 > 0:41:54leaving the mother struggling.
0:42:08 > 0:42:11This is a sign that the mother must head north
0:42:11 > 0:42:14to the more permanent icecap as quickly as possible.
0:42:17 > 0:42:23But a combination of wind and current destroys her best-laid plan.
0:42:25 > 0:42:29A sudden swell turns ice into open ocean.
0:42:43 > 0:42:46The cubs are too young to swim long distances safely.
0:42:56 > 0:42:59But going back is not an option.
0:43:04 > 0:43:07The cubs' only hope is to keep up.
0:43:07 > 0:43:11They paddle for their lives, staying as close to Mum as possible.
0:43:15 > 0:43:20She can swim 50 miles or more, but the cubs will soon be struggling.
0:43:26 > 0:43:30On the island, months of having to make do are taking their toll.
0:43:30 > 0:43:33The cub is half the size of those on the ice.
0:43:38 > 0:43:42A colony of walrus blocks their path.
0:43:42 > 0:43:44Just one would make a substantial meal.
0:43:48 > 0:43:52But walrus can weigh a ton and a half
0:43:52 > 0:43:55and their tusks can reach a metre in length,
0:43:55 > 0:43:56hardly a pushover.
0:44:02 > 0:44:05Her only hope is to find one that is weak or injured.
0:44:14 > 0:44:16She assesses the colony.
0:44:18 > 0:44:21With a cub to provide for, she can't take risks.
0:44:26 > 0:44:29She provokes the walrus to test their reactions.
0:44:29 > 0:44:30SHE GROWLS
0:44:30 > 0:44:32GRUMBLING
0:44:37 > 0:44:41All are healthy. She won't take the gamble.
0:44:49 > 0:44:52But all is not lost.
0:44:52 > 0:44:54She has caught a new scent.
0:45:07 > 0:45:09The cubs are in trouble.
0:45:13 > 0:45:15They are exhausted.
0:45:15 > 0:45:19The male cub rests his head on his sister.
0:45:24 > 0:45:28They crowd into the mother's slipstream, trying to gain any advantage.
0:45:43 > 0:45:47At last there is hope.
0:46:07 > 0:46:12They have finally reached the pack ice that forms the polar icecap.
0:46:12 > 0:46:16It's the ultimate hunting habitat for polar bears.
0:46:16 > 0:46:19The icecap stretches all the way to the North Pole.
0:46:19 > 0:46:22Seals are found wherever it meets the sea.
0:46:33 > 0:46:35It's been a long journey.
0:46:35 > 0:46:38They are 100 miles from Svalbard
0:46:38 > 0:46:41and 150 miles from the den-sites where they were born.
0:46:49 > 0:46:53For now she can relax, having fulfilled her mission.
0:46:53 > 0:46:56It's the perfect spot to spend the few months left of summer.
0:47:03 > 0:47:07It is four months since Svalbard was surrounded by sea-ice.
0:47:07 > 0:47:11It could be another two before it freezes again.
0:47:11 > 0:47:13Guided by her sense of smell,
0:47:13 > 0:47:17the mother discovers what's left of the stranded whale.
0:47:18 > 0:47:21But it looks like the remains have been stripped clean by bears.
0:47:24 > 0:47:26The massive backbone says it all.
0:47:26 > 0:47:29There's not a scrap to be found.
0:47:42 > 0:47:44This was their last hope.
0:47:51 > 0:47:56With the carcass gone, the bears search the shore for scraps.
0:47:56 > 0:47:59All that remains are sun-bleached bones.
0:48:03 > 0:48:05There is little nutrition here,
0:48:05 > 0:48:08but at least the cub has found something to chew on.
0:48:12 > 0:48:17Calcium from the bones will help the mother's milk supply
0:48:17 > 0:48:19but the cub needs meat to survive.
0:48:25 > 0:48:28Now they have another problem.
0:48:32 > 0:48:36Other bears can't be trusted with small cubs.
0:48:43 > 0:48:48But fortunately they seem more interested in what lies beneath the surface.
0:48:59 > 0:49:02It looks like there is still meat to be found here,
0:49:02 > 0:49:05partially preserved by the cold water.
0:49:17 > 0:49:21Despite her hunger, the mother can't risk joining in.
0:49:25 > 0:49:28But the other bears don't stay long.
0:49:32 > 0:49:35The mother grasps her opportunity.
0:49:35 > 0:49:38Her cub's survival depends on her success.
0:49:50 > 0:49:53The remains lie four metres down.
0:49:58 > 0:50:02And, at the deepest point, flesh still clings to the backbone.
0:50:07 > 0:50:10She emerges triumphant.
0:50:19 > 0:50:23The meat must be rancid, but it's still a lifesaver.
0:50:37 > 0:50:39She brings some back to the shore.
0:50:46 > 0:50:51This is the moment the cub has been waiting for, but still he has to wait.
0:50:51 > 0:50:52However unfair it seems,
0:50:52 > 0:50:56she must regain her strength or her cub won't survive anyway.
0:51:05 > 0:51:08Finally, she leaves him some scraps to chew on.
0:51:15 > 0:51:19A young male arrives, a dangerous situation for the cub.
0:51:28 > 0:51:32She growls a warning, but it's not enough.
0:51:41 > 0:51:43The cub slips.
0:52:00 > 0:52:04The mother must get her cub away from danger as quickly as possible.
0:52:08 > 0:52:10They head north.
0:52:10 > 0:52:15She knows that this is where the ice, and with it the seals, will first return.
0:52:20 > 0:52:26It's now September, but the sea might not freeze again for another two months.
0:52:26 > 0:52:30Her cub is unlikely to survive that long.
0:52:35 > 0:52:38But there is hope on the horizon.
0:52:45 > 0:52:48An ice-rainbow heralds change.
0:52:56 > 0:52:59In the far north, temperatures drop at last
0:52:59 > 0:53:02and ice sheets start to grow rather than disappear.
0:53:10 > 0:53:12Then a miracle happens.
0:53:12 > 0:53:16Building pressure combines with powerful southerly currents
0:53:16 > 0:53:19to push the drift-ice southwards.
0:53:37 > 0:53:40The mother and cub are thrown a lifeline
0:53:40 > 0:53:43by a change in the weather and ocean currents.
0:53:47 > 0:53:51It's a huge swim out to the ice floes for the little cub.
0:54:09 > 0:54:12He finally makes it to the ice,
0:54:12 > 0:54:14nine months after he was born.
0:54:16 > 0:54:21His mother has triumphed against the odds to reach this land of plenty.
0:54:23 > 0:54:27On the way, she taught her cub the survival skills
0:54:27 > 0:54:30for what could be an increasingly ice-free future.
0:54:40 > 0:54:42More than anything,
0:54:42 > 0:54:45the cub learnt that curiosity is the key to survival.
0:54:46 > 0:54:48But there is one more challenge ahead.
0:54:52 > 0:54:54A young male has caught a seal.
0:55:04 > 0:55:08They can't walk away from the chance of fresh meat.
0:55:08 > 0:55:12He charges, but she refuses to be intimidated.
0:55:12 > 0:55:15She needs a meal far more than he does.
0:55:17 > 0:55:19She drives home her determination.
0:55:28 > 0:55:32Well-fed bears eat only the blubber, leaving the rest for others.
0:55:35 > 0:55:37They waited the whole summer for this moment.
0:55:37 > 0:55:41Their first taste of fresh meat for four months.
0:55:41 > 0:55:44They are safe from starvation.
0:55:59 > 0:56:02Of all the subjects ever filmed by spycams,
0:56:02 > 0:56:06the polar bear has shown the greatest curiosity and intelligence.
0:56:06 > 0:56:09And none more so than this mother.
0:56:10 > 0:56:12Against the odds, she brought her cub up
0:56:12 > 0:56:17in one of the longest periods without ice in Svalbard's history.
0:56:17 > 0:56:22The cub faced many challenges over the summer, but to reveal his story
0:56:22 > 0:56:25the spy cameras faced challenges of their own.
0:56:27 > 0:56:32Snowcam met its demise under the paws of a bored young male.
0:56:44 > 0:56:46Blizzardcam nearly met its match
0:56:46 > 0:56:49with the most playful bear it ever encountered.
0:56:52 > 0:56:55The bear wanted to know how it worked.
0:57:00 > 0:57:04Blizzardcam deployed snowballcam as a decoy.
0:57:06 > 0:57:10This was the polar bears' favourite spy camera
0:57:10 > 0:57:13and this young male was no exception.
0:57:13 > 0:57:17Never before had it come under so much pressure.
0:57:29 > 0:57:33Valiantly, snowballcam kept filming until the very end.
0:57:37 > 0:57:40Fortunately, for most of the time,
0:57:40 > 0:57:45the spycams were ignored, capturing intimate moments like this.
0:57:45 > 0:57:49But icebergcam finally found itself trapped between ice floes.
0:57:57 > 0:58:01As ever, the mother's curiosity is piqued.
0:58:05 > 0:58:10The curiosity that helped the mother and cub survive
0:58:10 > 0:58:13is now testing icebergcam to destruction.
0:58:14 > 0:58:21This same curiosity is this cub's, and all polar bears', best hope for the future.
0:58:52 > 0:58:54Subtitles by Red Bee Media Ltd
0:58:54 > 0:58:56E-mail subtitling@bbc.co.uk