0:00:09 > 0:00:13Beneath some of the most demanding ski-runs in the world,
0:00:13 > 0:00:17Whistler, in Canada, is hiding a secret.
0:00:26 > 0:00:28Winter and summer,
0:00:28 > 0:00:31Whistler is a magnet for thrill-seekers.
0:00:32 > 0:00:36But it's not just people who crowd the black runs.
0:00:39 > 0:00:43The slopes are also home to black bears -
0:00:43 > 0:00:45the highest concentration in the world.
0:00:47 > 0:00:52So what is it about Whistler that makes it so appealing to bears?
0:01:03 > 0:01:05For the entire winter,
0:01:05 > 0:01:07the slopes are bear-free,
0:01:07 > 0:01:09but the bears ARE here,
0:01:09 > 0:01:11hidden in dens beneath the snow.
0:01:11 > 0:01:14They're waiting for spring.
0:01:15 > 0:01:20By the end of April, even artificial snow can't prolong the ski season for ever.
0:01:28 > 0:01:31As temperatures continue to rise,
0:01:31 > 0:01:34it's time for black bears and their new-born cubs
0:01:34 > 0:01:36to emerge from their dens.
0:01:40 > 0:01:43Many of the bears here are monitored by researchers,
0:01:43 > 0:01:45including this female, Jess,
0:01:45 > 0:01:49who brings two male cubs into the world for the first time.
0:01:56 > 0:01:59All the bears here are now intent on one thing -
0:01:59 > 0:02:01finding food,
0:02:01 > 0:02:04and that's the main thing which attracts them to Whistler.
0:02:07 > 0:02:09Exposed to the sun,
0:02:09 > 0:02:12the now snow-free ski-runs are covered in rich grasses
0:02:12 > 0:02:14and high-protein clover.
0:02:21 > 0:02:22BIRD SQUAWKS
0:02:22 > 0:02:24But for Jess and her cubs,
0:02:24 > 0:02:27this is not the start of a carefree summer.
0:02:28 > 0:02:31There are hostile males about.
0:02:38 > 0:02:41This male will kill Jess's cubs if it can,
0:02:41 > 0:02:44it's the only way for him to bring her back into season
0:02:44 > 0:02:46and have HIS cubs.
0:02:47 > 0:02:51The cubs' only safety is in the spindly upper branches.
0:03:03 > 0:03:06And Jess just has to brave it out.
0:03:16 > 0:03:19He backs off...this time.
0:03:31 > 0:03:33When the coast is clear,
0:03:33 > 0:03:35Jess and the cubs head further down the mountain
0:03:35 > 0:03:37to avoid another encounter.
0:03:37 > 0:03:41At the bottom of the valley lies the town of Whistler,
0:03:41 > 0:03:44and in the summer months many bears head for town
0:03:44 > 0:03:46to seek protection and food.
0:03:48 > 0:03:52Jess and her cubs are about to join life in the fast lane.
0:04:05 > 0:04:08The bears can detect even the faintest whiff of fast food
0:04:08 > 0:04:10with their fantastic sense of smell.
0:04:21 > 0:04:23Undeterred by all the attention,
0:04:23 > 0:04:26the bears stay focused on their mission.
0:04:29 > 0:04:33Fast-food leftovers give the bears a boost in the race to fatten up
0:04:33 > 0:04:36before their next hibernation.
0:04:39 > 0:04:42Jess and her cubs' constant search for food
0:04:42 > 0:04:44could lead them into trouble.
0:04:48 > 0:04:51Wiser bears wait for sunset.
0:05:07 > 0:05:09Most bins are bear-proofed,
0:05:09 > 0:05:12but if one is mistakenly left open,
0:05:12 > 0:05:15it's an opportunity that can't be missed.
0:05:18 > 0:05:20DOGS BARK
0:05:38 > 0:05:42Come early autumn, it's berry season for bears.
0:05:44 > 0:05:47With only two months to go before hibernation,
0:05:47 > 0:05:49this time of the year triggers a change
0:05:49 > 0:05:52in the bears' bodies and behaviour.
0:05:52 > 0:05:56They can eat for 18 hours a day without feeling full,
0:05:56 > 0:05:58and gain up to 30lbs a week.
0:06:01 > 0:06:04Berries are not just in the mountains.
0:06:04 > 0:06:06They also grow in Whistler town,
0:06:06 > 0:06:08which means Jess and her cubs
0:06:08 > 0:06:11don't have to budge from their summer home.
0:06:18 > 0:06:21They're so focused on feeding at this time
0:06:21 > 0:06:25that people have to be extra vigilant to avoid bumping into them.
0:06:30 > 0:06:33Bears becoming too familiar with humans
0:06:33 > 0:06:35puts the bears AND humans at risk.
0:06:39 > 0:06:41And down at the driving range
0:06:41 > 0:06:44there are more than water hazards to contend with.
0:06:45 > 0:06:50Jess and her cubs are breakfasting on the lush grass of the fairway...
0:06:50 > 0:06:52with the odd sandwich on the side.
0:07:02 > 0:07:04As the summer progresses,
0:07:04 > 0:07:07Jess is getting more and more belligerent,
0:07:07 > 0:07:09and her cubs are watching her every move.
0:07:13 > 0:07:16Smash-and-grab is now their preferred strategy.
0:07:24 > 0:07:28And at this time of year, it's each cub for himself.
0:07:34 > 0:07:38Reinforcements simply push them into another feeding patch.
0:07:40 > 0:07:42But as long as everyone sticks to the rules,
0:07:42 > 0:07:46town-dwellers can live amicably together.
0:07:52 > 0:07:54Jess and her cubs' summer in the city
0:07:54 > 0:07:57has got them fat enough to survive the winter.
0:07:59 > 0:08:02But it leaves them with a difficult legacy -
0:08:02 > 0:08:05the cubs now have little fear of humans.
0:08:07 > 0:08:10The habits they've learned from their mother
0:08:10 > 0:08:11are now deeply ingrained,
0:08:11 > 0:08:14and might get them into big trouble in future.
0:08:15 > 0:08:17As winter approaches,
0:08:17 > 0:08:21it's time for Jess, her cubs and all the other city bears
0:08:21 > 0:08:23to head out of town and back up the slopes.
0:08:25 > 0:08:28Jess will hibernate with her cubs for six months,
0:08:28 > 0:08:31but next summer they'll have to fend for themselves.
0:08:31 > 0:08:33The question is,
0:08:33 > 0:08:37when they're on their own, will the bears be back in town?
0:08:45 > 0:08:48Subtitles by Palma McKeown, Red Bee Media Ltd 2007
0:08:48 > 0:08:51E-mail subtitling@bbc.co.uk