0:00:02 > 0:00:04This is Deadly 360.
0:00:05 > 0:00:07The show that pits three of the world's deadliest predators
0:00:07 > 0:00:09against their prey.
0:00:10 > 0:00:15Examining both their hunting strategies and their escape tactics
0:00:15 > 0:00:16from every angle.
0:00:18 > 0:00:20By delving beneath the fur and the feathers,
0:00:20 > 0:00:22we'll find out why a hunt succeeds.
0:00:23 > 0:00:26And why they sometimes fail.
0:00:26 > 0:00:31One thing's certain, prey animals are anything but sitting ducks.
0:00:31 > 0:00:34Their defensive strategies keep them alive.
0:00:36 > 0:00:40And push predators to the limits.
0:00:40 > 0:00:42Prepare for Deadly 360.
0:00:44 > 0:00:47This is Deadly 360 mission control,
0:00:47 > 0:00:51where all of today's action and analysis takes place.
0:00:51 > 0:00:57From here, we have access to some of the most enthralling hunts
0:00:57 > 0:00:59that have ever been caught on camera.
0:00:59 > 0:01:02I've recreated three of the most exciting and analysed them
0:01:02 > 0:01:05from different angles and perspectives
0:01:05 > 0:01:08in true 360-degree style.
0:01:08 > 0:01:11The predators we're looking at have to catch food
0:01:11 > 0:01:12or they just won't make it.
0:01:12 > 0:01:14In the wild world,
0:01:14 > 0:01:17simply managing to survive is the greatest challenge of all.
0:01:17 > 0:01:19I present to you, the bears.
0:01:19 > 0:01:23The bear family contains the largest land carnivores in the world,
0:01:23 > 0:01:26so these three all pack a mighty punch.
0:01:26 > 0:01:30We'll head to Alaska, home of the most famous brown bear of all,
0:01:30 > 0:01:32the grizzly.
0:01:32 > 0:01:35And in the Indian forests, we'll see a stealthy sloth bear
0:01:35 > 0:01:38use the cover of night to try a smash-and-grab raid.
0:01:38 > 0:01:42And this bear is the world's largest terrestrial carnivore.
0:01:42 > 0:01:45A master predator from a frozen world. The polar bear.
0:01:45 > 0:01:50Three bears, three very different hunting strategies, all deadly.
0:01:51 > 0:01:53They look invincible.
0:01:53 > 0:01:56But there's a continual arms race going on in nature
0:01:56 > 0:01:58which ensures that prey animals are always evolving
0:01:58 > 0:02:01spectacular ways of taking care of themselves.
0:02:03 > 0:02:06In this show, the three animals fighting for their lives
0:02:06 > 0:02:09are the Pacific salmon, speedsters of the seas and rivers.
0:02:09 > 0:02:13The ringed seal, a fast and agile underwater acrobat.
0:02:15 > 0:02:16And finally, the termite.
0:02:16 > 0:02:21A colony of hundreds of thousands of individuals with an army for defence.
0:02:21 > 0:02:24Three prey with very different survival skills
0:02:24 > 0:02:27to outsmart even the most accomplished killers.
0:02:28 > 0:02:31So I've introduced you to all of our contenders.
0:02:31 > 0:02:34Now it's time to meet our first deadly duo going head to head.
0:02:36 > 0:02:40This bear is the world's largest terrestrial carnivore.
0:02:40 > 0:02:43A master predator from a frozen world.
0:02:43 > 0:02:44The polar bear.
0:02:45 > 0:02:47Up against it is this.
0:02:49 > 0:02:50The ringed seal.
0:02:50 > 0:02:54But which animal has the edge in the race for life?
0:02:54 > 0:02:57It's time to go Deadly 360.
0:03:00 > 0:03:04We join the action at this knife-edge moment.
0:03:04 > 0:03:06Just half a metre of snow and ice separates them.
0:03:06 > 0:03:09The seal's been underwater for over 20 minutes.
0:03:09 > 0:03:10It has to come up for breath soon,
0:03:10 > 0:03:13but the polar bear is waiting to strike.
0:03:15 > 0:03:18Even in a hunt like this, there are still a lot of factors in play,
0:03:18 > 0:03:21and to find out whether the hunter succeeds or fails,
0:03:21 > 0:03:27we need to wind back and build up the entire hunt right from the beginning.
0:03:28 > 0:03:33So first, let's check out where this epic battle is taking place.
0:03:33 > 0:03:35We're here, in the Arctic Circle.
0:03:35 > 0:03:38This vast, barren land is where the polar bear has made its home.
0:03:38 > 0:03:42Temperatures here can drop to minus 40 degrees,
0:03:42 > 0:03:44making this one of the toughest places in the world to live.
0:03:44 > 0:03:47And it might seem like there's nothing around
0:03:47 > 0:03:51in these frozen ice fields, but take a closer look and you'll see
0:03:51 > 0:03:53that scattered in amongst the snow,
0:03:53 > 0:03:56various animals are eking out a tough existence.
0:03:57 > 0:04:00This ringed seal can provide enough energy
0:04:00 > 0:04:03to keep a polar bear going for five days.
0:04:04 > 0:04:08I think it's fair to say this is a challenging environment for a hunt.
0:04:08 > 0:04:11But what do our two animals have that's going to give them an edge
0:04:11 > 0:04:13in such extreme conditions?
0:04:14 > 0:04:18The polar bear is armed with some of the best paws in the animal world.
0:04:18 > 0:04:22It's also built for endurance, with fantastic stamina.
0:04:22 > 0:04:25And it possesses a superb sense of smell,
0:04:25 > 0:04:27making it the top predator in the Arctic Circle.
0:04:29 > 0:04:33All of that makes our predator a pretty scary prospect.
0:04:33 > 0:04:35What does our prey have to counter?
0:04:37 > 0:04:39In the water, seals are speedy swimmers.
0:04:39 > 0:04:42Add to the mix some super senses
0:04:42 > 0:04:45and the fact it can hold its breath for half an hour,
0:04:45 > 0:04:48and the seal stands a fantastic chance of survival.
0:04:48 > 0:04:50Right. Back to the hunt.
0:04:52 > 0:04:55The seal's out of sight about a mile away, but despite this,
0:04:55 > 0:04:58the polar bear is currently working out its precise location.
0:04:58 > 0:05:01So how does it do it?
0:05:01 > 0:05:03Well, that nose is perhaps the most highly-tuned weapon
0:05:03 > 0:05:05in the polar bear's armoury.
0:05:07 > 0:05:12It's so sensitive, it can detect a seal carcass from over 20 miles away.
0:05:13 > 0:05:16So why does it need such an incredible sense of smell?
0:05:16 > 0:05:20Well, this place is an icy, barren wilderness.
0:05:20 > 0:05:25Life here is hard for any animal and prey is very few and far between.
0:05:25 > 0:05:29But actually, anything like a seal is going to leave behind a scent trail
0:05:29 > 0:05:32that can be detectable from far further away
0:05:32 > 0:05:34than the polar bear could possible see.
0:05:34 > 0:05:37All it has to do is move in towards the smell
0:05:37 > 0:05:39and find itself a seal meal.
0:05:40 > 0:05:44It's travelling the whole way over slippery ice and snow
0:05:44 > 0:05:46and you know how dangerous that can be.
0:05:46 > 0:05:51The polar bear is certainly very capable of taking care of itself.
0:05:52 > 0:05:55I mean, just look at the size of it standing up on its hind legs.
0:05:55 > 0:05:58They can be over three metres tall.
0:05:58 > 0:06:02In fact, the record was 3.7 metres tall.
0:06:02 > 0:06:04An animal this size is also very heavy.
0:06:04 > 0:06:07They can weigh as much as 800 kilograms,
0:06:07 > 0:06:10which is ten times the weight of an adult human being.
0:06:10 > 0:06:14But something that weighs this much and that lives on soft snow
0:06:14 > 0:06:16and potentially brittle ice
0:06:16 > 0:06:19is going to have tremendous problems in getting around.
0:06:20 > 0:06:23So how does it manage that?
0:06:23 > 0:06:26Let's have a look at the feet in more detail.
0:06:26 > 0:06:29First off, this is life-size.
0:06:29 > 0:06:32They can be as much as 30 centimetres across
0:06:32 > 0:06:36and that massive size spreads out the weight of the polar bear.
0:06:36 > 0:06:39It almost functions like a snow shoe.
0:06:39 > 0:06:43If we flip the foot over, you can see that it has soft pads
0:06:43 > 0:06:46that are covered with tiny bumps called papillae.
0:06:46 > 0:06:49These increase the surface area of the foot
0:06:49 > 0:06:51and function like the grips on a pair of trainers.
0:06:51 > 0:06:55And then these long, hooked claws work almost like crampons.
0:06:55 > 0:06:59They're the final way of keeping this animal sturdy on slippery ice.
0:07:02 > 0:07:05And the combination of those incredible paws
0:07:05 > 0:07:06and that superb sense of smell
0:07:06 > 0:07:09has brought the polar bear close to the seal.
0:07:09 > 0:07:12But it has hit a potential problem.
0:07:12 > 0:07:13The ice has run out.
0:07:13 > 0:07:17Those specially-adapted paws are perfect at all terrain navigation.
0:07:17 > 0:07:19It's straight into the water.
0:07:19 > 0:07:22The feet are webbed, meaning that when the ice runs out
0:07:22 > 0:07:25and the water begins, the polar bear can carry on its hunt for food.
0:07:25 > 0:07:29When it's in the water, the polar bear uses its front legs as paddles
0:07:29 > 0:07:32and the back legs act like rudders.
0:07:32 > 0:07:35They can swim for a very long way.
0:07:35 > 0:07:38Believe it or not, recently a polar bear was spotted swimming
0:07:38 > 0:07:42for nine days without coming to land and covered about 400 miles.
0:07:42 > 0:07:45And the endurance doesn't end with swimming.
0:07:45 > 0:07:48This is an animal that can cover as much as 100,000 square miles
0:07:48 > 0:07:50in its lifetime.
0:07:51 > 0:07:55But back in the hunt, it has broken cover at just the wrong moment.
0:07:55 > 0:07:58The seal escapes, diving back underwater. A big problem.
0:07:58 > 0:08:02While both can swim, the seal can hit speeds of 20 miles per hour,
0:08:02 > 0:08:04five times faster than the polar bear.
0:08:04 > 0:08:08The bear can only hunt on the surface so its chances are looking slim.
0:08:08 > 0:08:10But the hunt isn't over.
0:08:11 > 0:08:14Seals are sublime swimmers but they're mammals,
0:08:14 > 0:08:17which means they have to come back up to the surface to breathe.
0:08:17 > 0:08:21And when they do that, they leave themselves vulnerable to attack.
0:08:21 > 0:08:25How does a seal know which breathing hole is safe and which isn't?
0:08:25 > 0:08:29Well, this is when the seal's defensive tactics come into play.
0:08:29 > 0:08:31The seal has incredible underwater hearing
0:08:31 > 0:08:34and it's listening out for this.
0:08:34 > 0:08:36THUDDING
0:08:38 > 0:08:40As the polar bear walks across the ice,
0:08:40 > 0:08:42it's travelling very quietly.
0:08:42 > 0:08:45But an animal of that size creates vibrations
0:08:45 > 0:08:48that travel down through the ice and into the water below.
0:08:48 > 0:08:52Once the soundwaves are in the water, they travel four times faster
0:08:52 > 0:08:55than they would do in air, which means the seal can detect them,
0:08:55 > 0:08:58pick them up and move away from the source of the sounds.
0:08:58 > 0:09:01But it doesn't pick them up using its ears.
0:09:01 > 0:09:04Instead, it uses these whiskers.
0:09:04 > 0:09:07Many mammals have whiskers in their faces.
0:09:07 > 0:09:11They're connected to nerves which run straight into the brain
0:09:11 > 0:09:14and are incredibly sensitive, but particularly so in seals.
0:09:14 > 0:09:18They're said to be ten times more sensitive than a cat's whiskers.
0:09:18 > 0:09:21Now that obviously can be a real advantage if it helps them
0:09:21 > 0:09:24to locate the position of a polar bear.
0:09:24 > 0:09:26They can simply hear where it is
0:09:26 > 0:09:28and move away to a different breathing hole.
0:09:28 > 0:09:29Let's see how this plays out.
0:09:33 > 0:09:36The seal's busy moving away from the polar bear
0:09:36 > 0:09:39as it walks around on the surface looking for a meal.
0:09:39 > 0:09:42But the problems start when the bear stops.
0:09:42 > 0:09:45With no movement, there's no sound
0:09:45 > 0:09:48and the seal has no way of knowing where the polar bear is.
0:09:48 > 0:09:51It's essentially now blind in its underwater world.
0:09:52 > 0:09:54The bear has stopped beside a breathing hole.
0:09:54 > 0:09:56Seals usually breathe once every ten minutes
0:09:56 > 0:10:01but can hold off for 45 minutes in an emergency such as this.
0:10:01 > 0:10:05Polar bears are one of the most patient predators
0:10:05 > 0:10:07in the animal kingdom, able to lie in wait
0:10:07 > 0:10:11by a seal's breathing hole in temperatures down to -40 for hours.
0:10:11 > 0:10:14Sooner or later, the seal must come up for air.
0:10:16 > 0:10:18Essentially, this is now just a deadly waiting game.
0:10:18 > 0:10:22With no way of knowing where the bear is,
0:10:22 > 0:10:25and running out of air, the seal is going to have to surface.
0:10:25 > 0:10:28Once it starts surfacing, it's so buoyant it can't change direction.
0:10:28 > 0:10:30This is now just a question of luck.
0:10:38 > 0:10:40No! Don't do it! Oh!
0:10:40 > 0:10:43On this occasion, the bear's chosen the wrong breathing hole
0:10:43 > 0:10:46and the seal escapes with its life.
0:10:51 > 0:10:54The polar bear had to cover a vast area of wild,
0:10:54 > 0:10:57Arctic landscape just to narrow down its search.
0:10:57 > 0:11:00Even when it had all those holes to choose from,
0:11:00 > 0:11:02the odds were still in the seal's favour.
0:11:02 > 0:11:06The polar bear followed its sense of smell, showed great stamina
0:11:06 > 0:11:09and patience, and used its multi-purpose paws,
0:11:09 > 0:11:13but the seal's eyesight, incredibly sensitive whiskers
0:11:13 > 0:11:16and swimming skills meant it survived to see another day.
0:11:19 > 0:11:24Now onto our next pair of hunters locked in a battle for survival.
0:11:24 > 0:11:28This is the sloth bear, a secretive but nonetheless deadly hunter.
0:11:28 > 0:11:35And up against it is this, a teeming colony of termites.
0:11:35 > 0:11:40Which has the edge in the race for life? It's time to go Deadly 360.
0:11:44 > 0:11:47The sloth bear has arrived at the termite mound,
0:11:47 > 0:11:51home to up to a million individuals all ruled by a single queen.
0:11:51 > 0:11:54If she dies, the whole colony will die,
0:11:54 > 0:11:57so her loyal subjects will fight to the death to defend her.
0:11:57 > 0:12:01At only a fraction of the bear's size, how can they possibly win?
0:12:01 > 0:12:02Well, based on size alone,
0:12:02 > 0:12:06you'd have to say it looks like the prey is done for.
0:12:06 > 0:12:10Don't give up hope just yet. It's rarely as simple as that.
0:12:10 > 0:12:13Let's rewind to the start of the hunt and begin our investigation.
0:12:15 > 0:12:18We're heading over to India for this one,
0:12:18 > 0:12:23to a forest in the south-west of the country.
0:12:23 > 0:12:27This wooded world is vastly different to the ice fields
0:12:27 > 0:12:28where the polar bear lives.
0:12:28 > 0:12:31It's hot, humid and bursting with life.
0:12:31 > 0:12:35These trees provide all the food the vegetarian termites could want,
0:12:35 > 0:12:39but it's so warm during the day that the furry sloth bear has to rest up
0:12:39 > 0:12:43in these trees and wait for the cool of the night to carry out its hunt.
0:12:43 > 0:12:46Only once it's dark can it start searching for food
0:12:46 > 0:12:48using its impressive weapons.
0:12:48 > 0:12:51Smell is vitally important for the sloth bear,
0:12:51 > 0:12:54and check out its incredibly powerful front legs,
0:12:54 > 0:12:57with large claws designed for a smash-and-grab lifestyle.
0:12:57 > 0:13:02So I think it's clear we're dealing with another well-equipped predator.
0:13:02 > 0:13:06But how's our prey going to try to neutralise the threat?
0:13:09 > 0:13:12One-on-one, they don't stand a chance, but they have numbers.
0:13:12 > 0:13:16There can be almost a million of them in just one colony.
0:13:16 > 0:13:20They are also able to build a clay castle to protect themselves.
0:13:20 > 0:13:22Add to that an army of powerful biting jaws
0:13:22 > 0:13:27to deter an attacker, and you've got a valiant and worthy opponent.
0:13:27 > 0:13:29We have two very different animals,
0:13:29 > 0:13:32but which one's going to come out on top in this hunt?
0:13:32 > 0:13:37Let's find out. The Indian nights may be cool enough for the sloth bear to hunt in,
0:13:37 > 0:13:41but there are disadvantages to finding food in the dark.
0:13:41 > 0:13:45Let's look at how the bear has adapted its senses to hunt at night.
0:13:45 > 0:13:48First up, its eyesight.
0:13:48 > 0:13:51Its eyes are quite small and the eyesight isn't that well-developed,
0:13:51 > 0:13:54but it's a nocturnal species, it's out at night.
0:13:54 > 0:13:59It could either have night vision or it could rely on other senses.
0:13:59 > 0:14:01That's exactly what the sloth bear does.
0:14:01 > 0:14:05Actually, its main weapon is that incredible nose.
0:14:05 > 0:14:08But while the sloth bear is sniffing out its supper,
0:14:08 > 0:14:10let's have a look at the termite colony.
0:14:12 > 0:14:16This vast structure is the termites' home, and has been constructed
0:14:16 > 0:14:20by millions upon millions of termites over many generations.
0:14:20 > 0:14:23In the depths lies the royal chamber, the queen's home.
0:14:24 > 0:14:26She's ten times bigger than the other termites
0:14:26 > 0:14:29but is so large that she can't move and is totally defenceless.
0:14:29 > 0:14:32She therefore gives birth to hundreds of thousands
0:14:32 > 0:14:36of workers, whose job it is to build this fortress around her.
0:14:36 > 0:14:39These solid walls provide a real,
0:14:39 > 0:14:42physical barrier to the outside world, and it's a great way
0:14:42 > 0:14:46of making sure that predators can't get to the inside of the mound.
0:14:46 > 0:14:49The termites look as though they're really safe
0:14:49 > 0:14:51inside their hard-baked clay home.
0:14:51 > 0:14:54Let's find out what our sloth bear is up to.
0:14:55 > 0:14:57The sloth bear has sniffed out the termite mound,
0:14:57 > 0:15:01but is faced with a seemingly impenetrable fortress.
0:15:01 > 0:15:04Undeterred, it starts sniffing around the mound whilst testing
0:15:04 > 0:15:07different areas, checking to see if there are any weaker points.
0:15:07 > 0:15:09Once it has found one,
0:15:09 > 0:15:13it starts tearing into it with those incredibly powerful front legs.
0:15:13 > 0:15:16To help it, each paw is armed with monstrous claws.
0:15:16 > 0:15:18Each one is seven centimetres long
0:15:18 > 0:15:24and curved, a perfect shape for dismantling a termite mound.
0:15:24 > 0:15:26The termites' first line of defence has been breached,
0:15:26 > 0:15:28leaving them exposed to a predator
0:15:28 > 0:15:30around 4m times their weight.
0:15:30 > 0:15:33If the bear gets deeper inside the mound and eats the queen,
0:15:33 > 0:15:35the whole colony will die.
0:15:35 > 0:15:37Look at the way the bear's eating them.
0:15:37 > 0:15:39The trick to becoming
0:15:39 > 0:15:42an expert termite muncher is all down to the design of its mouth.
0:15:45 > 0:15:49Let's tell the tale of the bones beneath those rubbery lips.
0:15:49 > 0:15:51This is a sloth bear skull.
0:15:51 > 0:15:55The interesting thing about it, really, is that it has a long snout,
0:15:55 > 0:15:59perfect for getting inside the nooks and crannies of termite mounds.
0:15:59 > 0:16:02This normally, as a young bear,
0:16:02 > 0:16:05would be completely filled in with teeth. It has 42 in total.
0:16:05 > 0:16:08But when it loses its milk teeth and gains its adult set,
0:16:08 > 0:16:12the top two in the middle never grow back.
0:16:12 > 0:16:15Essentially what it's done is turned its whole head
0:16:15 > 0:16:18into a straw for sucking up termites.
0:16:18 > 0:16:20The amount of suction it can get,
0:16:20 > 0:16:23just hoovering up those insects, is incredible.
0:16:23 > 0:16:26Let's see all of this in action.
0:16:29 > 0:16:32The sloth bear is hoovering up the termites with that
0:16:32 > 0:16:35incredible mouth, and can eat hundreds per minute.
0:16:35 > 0:16:39The fortress built by the worker termites has been breached,
0:16:39 > 0:16:41leaving the colony open to attack.
0:16:41 > 0:16:45The worker termites are construction workers, with no weapons.
0:16:45 > 0:16:48The queen isn't done for yet.
0:16:48 > 0:16:49As well as the workers,
0:16:49 > 0:16:53she lays another type of termite crucial in termite society.
0:16:53 > 0:16:56Soldiers.
0:16:56 > 0:17:01The function of soldier termites is given away by their name.
0:17:01 > 0:17:04Their only function is to defend the termite mound.
0:17:04 > 0:17:08Looking at the body shape of the termite,
0:17:08 > 0:17:11the first thing you notice is that the head takes up an enormous
0:17:11 > 0:17:13percentage of the whole animal.
0:17:13 > 0:17:15There's a reason for that,
0:17:15 > 0:17:18and it's not because it has a large brain or big eyes or anything.
0:17:18 > 0:17:23It's all about powerful muscles driving those fearsome weapons.
0:17:23 > 0:17:27These jaws close with the fastest strike of any
0:17:27 > 0:17:28in the whole animal kingdom.
0:17:28 > 0:17:31When it comes to taking the role of defending its home,
0:17:31 > 0:17:33they are second-to-none.
0:17:33 > 0:17:35Let's see how all of this functions
0:17:35 > 0:17:38against a large predator like a bear.
0:17:39 > 0:17:42The holes in the termite mound walls cause a sudden change
0:17:42 > 0:17:45in the constant internal atmosphere.
0:17:45 > 0:17:48This is a sign the soldier termites had been waiting for.
0:17:48 > 0:17:50The soldiers drum their heads against the walls,
0:17:50 > 0:17:53a battle cry to the rest of the soldier termites.
0:17:53 > 0:17:55Alert to the danger, the other soldiers rush
0:17:55 > 0:17:58to where their castle walls have been breached.
0:17:58 > 0:18:00Their jaws are primed and ready to nip
0:18:00 > 0:18:02and cut at anything in their way.
0:18:02 > 0:18:04Termite bites may be small in comparison,
0:18:04 > 0:18:10but nonetheless irritating. The bear is doing its best to avoid being bitten
0:18:10 > 0:18:12with that incredible hoovering mouth.
0:18:12 > 0:18:16But the termites' strength in numbers and defence is beginning to take effect.
0:18:16 > 0:18:19Many lost their lives, but with so many soldiers in the colony,
0:18:19 > 0:18:22the sloth bear is finding the bites too uncomfortable
0:18:22 > 0:18:25and it leaves the termite mound with the queen still alive.
0:18:25 > 0:18:28The soldier termites have done their job.
0:18:30 > 0:18:34The sloth bear appeared to have all the weaponry on its side,
0:18:34 > 0:18:37but actually, even though it managed to get itself a meal,
0:18:37 > 0:18:41it was really such a tiny fraction of the termite colony that was eaten
0:18:41 > 0:18:44that I think I'm going to call this one a victory for the insects.
0:18:44 > 0:18:48The sloth bear's sensitive nose, destructive front legs
0:18:48 > 0:18:53and specially adapted mouth meant it launched a full-on attack.
0:18:53 > 0:18:59The termites' strength in numbers, home and aggressive soldiers eventually subdued the bear.
0:19:03 > 0:19:09This is our last deadly duo, locked in a battle for life or death.
0:19:09 > 0:19:13This is the grizzly bear, an expert fisherman.
0:19:13 > 0:19:18Up against it is this. The Pacific salmon.
0:19:18 > 0:19:25Which has the edge in the race for life? This is Deadly 360.
0:19:27 > 0:19:30We join the action before the moment of impact.
0:19:30 > 0:19:34And this has to be every salmon's nightmare.
0:19:34 > 0:19:37It has to run the gauntlet against an army of hungry
0:19:37 > 0:19:38grizzly bear mouths.
0:19:38 > 0:19:42To add to the problem, a raging waterfall is forcing it back.
0:19:42 > 0:19:45It has strength in numbers but with a fast river and the expert
0:19:45 > 0:19:49fishing skills of the grizzlies, has it got the skills to survive?
0:19:50 > 0:19:53If we freeze the action at this crucial moment,
0:19:53 > 0:19:56who do you think the odds favour, the predator or the prey?
0:19:56 > 0:19:59To find out, let's take it back to the start
0:19:59 > 0:20:02and build up the entire hunt right from the beginning.
0:20:04 > 0:20:06This hunt takes place here, in Alaska,
0:20:06 > 0:20:10and more specifically the Yukon river,
0:20:10 > 0:20:13which leads from the salmon's home in the ocean
0:20:13 > 0:20:16to their breeding-grounds at the top of the river.
0:20:16 > 0:20:20This is the epic last trip in the salmon's lifetime.
0:20:20 > 0:20:23It, along with all the others, is making its way back
0:20:23 > 0:20:26to breed in the same river that it hatched in several years ago,
0:20:26 > 0:20:31where it will then die, if it makes it past the bears.
0:20:31 > 0:20:34The grizzly is trying to catch it before it gets too far upstream,
0:20:34 > 0:20:38with a nose capable of smelling fish that are underwater,
0:20:38 > 0:20:39lightening-fast reactions
0:20:39 > 0:20:44and claws that can stop a fish dead in its tracks.
0:20:44 > 0:20:47So with all that to help it hunt,
0:20:47 > 0:20:51you'd think that our predator would have no trouble making a kill.
0:20:51 > 0:20:55But our prey also has some pretty nifty means of defence.
0:20:56 > 0:21:01Salmon are hugely impressive fish, capable of out-manoeuvring their foe.
0:21:03 > 0:21:06With a burst of speed that can launch it through the air,
0:21:06 > 0:21:11together with sheer numbers, and some super senses,
0:21:11 > 0:21:14the salmon has all the necessary skills to survive.
0:21:16 > 0:21:19Let's join the action at the start of the day as the grizzly bear
0:21:19 > 0:21:22begins its search for some fishy food.
0:21:22 > 0:21:24The glut of salmon is known as the salmon run
0:21:24 > 0:21:27and is vitally important for the grizzly as it needs to feast
0:21:27 > 0:21:31on these energy-packed fish in order to fatten up for winter.
0:21:31 > 0:21:34If it doesn't put on another 50% of its bodyweight over the next
0:21:34 > 0:21:37few months, it won't have enough fat reserves
0:21:37 > 0:21:40to survive the harsh winter.
0:21:40 > 0:21:43So the bear starts the hunt when the salmon starts the run.
0:21:43 > 0:21:46The bear's using a combination of sight and smell to pick up its meal.
0:21:46 > 0:21:48Look at the way it's dropping its nose down
0:21:48 > 0:21:50to the surface of the water.
0:21:50 > 0:21:55Believe it or not, it can scent the oils left by the fish as they swim.
0:21:55 > 0:21:59With this many salmon around, it looks sure to pick up a meal.
0:21:59 > 0:22:01The salmon's tactic of shoaling together
0:22:01 > 0:22:04is its first line of defence.
0:22:04 > 0:22:06By congregating in such a large group,
0:22:06 > 0:22:09it means the odds of individual survival are far greater
0:22:09 > 0:22:11than if it tried to go it alone.
0:22:11 > 0:22:13You'd think with this much salmon around,
0:22:13 > 0:22:15it would be time for an easy meal.
0:22:15 > 0:22:18That couldn't be further from the truth.
0:22:18 > 0:22:21In fact, if anything, there's just too much salmon here.
0:22:21 > 0:22:24Every time the bear gets fixed on one salmon, she goes for it,
0:22:24 > 0:22:27sees another and goes for that one instead.
0:22:27 > 0:22:30Actually, it's just being overwhelmed.
0:22:30 > 0:22:33It's like a computer going through information overload.
0:22:33 > 0:22:37Because the water's deep, there's plenty ways for the salmon to escape.
0:22:37 > 0:22:40If the bear stays here for much longer,
0:22:40 > 0:22:43she's simply going to get tired and then hungry.
0:22:43 > 0:22:47The only way this bear's going to get a meal is by heading further inland.
0:22:57 > 0:22:59The bears move further upstream and find a pool packed
0:22:59 > 0:23:02with resting salmon after a tiring first leg of their journey.
0:23:05 > 0:23:08The bear can see the salmon from the surface
0:23:08 > 0:23:11but can also stick its head underwater to take a better look.
0:23:11 > 0:23:14It's as if it's got built-in swimming goggles.
0:23:14 > 0:23:18The salmon haven't decided to rest in any old part of the river,
0:23:18 > 0:23:20this pool is like the river mouth,
0:23:20 > 0:23:23sufficiently deep enough to allow them to get away.
0:23:24 > 0:23:28As the bear closes in, look at the way the fish peel apart,
0:23:28 > 0:23:30swimming away from it easily in shoals.
0:23:30 > 0:23:33They have special sensors running down their bodies,
0:23:33 > 0:23:35they can sense the bear
0:23:35 > 0:23:38long before it can get anywhere close to them.
0:23:38 > 0:23:43Bears are massive, heavy, powerful animals.
0:23:43 > 0:23:45The shape of their paws reflects that.
0:23:45 > 0:23:48You might think, looking at the size of it,
0:23:48 > 0:23:51that it's clumsy, but that couldn't be further from the truth.
0:23:51 > 0:23:55Those long claws can be used to tear off bark to find insects,
0:23:55 > 0:23:57even to open up shellfish
0:23:57 > 0:24:01and definitely as a tool for tearing apart fish.
0:24:01 > 0:24:05Our bear is heading upstream to see if it can find itself a decent meal.
0:24:09 > 0:24:12Back in the hunt, the bear is further upstream,
0:24:12 > 0:24:14looking for fresh fish.
0:24:14 > 0:24:16The salmon's way is blocked
0:24:16 > 0:24:18by grizzly bears and a two-metre waterfall.
0:24:18 > 0:24:20They appear to be trapped in a dead end.
0:24:20 > 0:24:23The odds now appear to be in the grizzly's favour.
0:24:23 > 0:24:28She joins the others for a chance to feast on the cornered fish.
0:24:28 > 0:24:31The salmon wouldn't get very far if they gave up every time
0:24:31 > 0:24:34they got near a waterfall.
0:24:34 > 0:24:39They do have one particular twist in the tale. Look at this.
0:24:39 > 0:24:45That is an incredible leap. How on Earth do the salmon manage it?
0:24:45 > 0:24:50A salmon is essentially one big swimming muscle.
0:24:50 > 0:24:54It's shaped kind of like a torpedo, narrowing towards the back,
0:24:54 > 0:24:55where the tail is.
0:24:55 > 0:25:01Then this extended tail is fantastic at driving it along at great speeds.
0:25:01 > 0:25:04The way they achieve that is by having a body shape
0:25:04 > 0:25:06which is extremely hydro-dynamic.
0:25:06 > 0:25:08That means it has very little drag in water.
0:25:08 > 0:25:13When it leaps, it is also extraordinarily capable.
0:25:13 > 0:25:17They can travel at eight metres per second through the air
0:25:17 > 0:25:20and leap up to three-and-a-half metres in height.
0:25:20 > 0:25:25This is an animal that's almost like a high-velocity underwater bullet.
0:25:26 > 0:25:29Right, let's see it in action against our bear.
0:25:32 > 0:25:37Armed with those impressive muscles, the salmon joins up with the others
0:25:37 > 0:25:41as it works out the best line of attack to safely get up the river.
0:25:41 > 0:25:46The grizzly is looking to outsmart it with lightning-fast reactions.
0:25:46 > 0:25:49The first salmon tries to get past the bear
0:25:49 > 0:25:51and launches forward using those muscles.
0:25:51 > 0:25:54Just look at the way it spears through the air.
0:25:54 > 0:25:57The bear is too far and the salmon makes it.
0:25:57 > 0:26:00Sometimes you have to be persistent to successfully catch a meal.
0:26:00 > 0:26:04There are so many fish that the bear just has to be patient
0:26:04 > 0:26:07and hope that one of them makes the mistake of jumping close to danger.
0:26:07 > 0:26:09The next salmon tries its luck,
0:26:09 > 0:26:12but it's on a collision-course with the bear.
0:26:12 > 0:26:14This should be game over.
0:26:14 > 0:26:16But it catches the bear out
0:26:16 > 0:26:19and safely falls back into the water, lucky to still be alive.
0:26:19 > 0:26:26Another salmon decides it's now or never. Oh! That was extraordinary!
0:26:26 > 0:26:27Let's see that again.
0:26:27 > 0:26:31OK, the fish is powering its way through heavily aerated water.
0:26:31 > 0:26:33It makes its leap but the bear has clocked it.
0:26:33 > 0:26:35You can see she's zeroing in on the fish.
0:26:35 > 0:26:40Opens its mouth and swings in for about the most perfect catch
0:26:40 > 0:26:42you will ever see.
0:26:42 > 0:26:45She's going to take the fish to a safer place,
0:26:45 > 0:26:49away from the waterfall, to enjoy her well-earned meal.
0:26:49 > 0:26:51For such a large animal,
0:26:51 > 0:26:53this is a challenging way of hunting.
0:26:53 > 0:26:56She's standing in a waterfall, trying to catch a leaping,
0:26:56 > 0:26:58slippery fish in her mouth.
0:26:58 > 0:27:00At this time of year,
0:27:00 > 0:27:02the salmon protein is absolutely essential
0:27:02 > 0:27:06for her survival, so it's just as well that she succeeded.
0:27:06 > 0:27:10The salmon has strength in numbers, a torpedo-shaped body
0:27:10 > 0:27:12and powerful leaping muscles.
0:27:13 > 0:27:16But the grizzly's sensitive nose, nifty paws
0:27:16 > 0:27:22and biting jaws were simply too good for the salmon on this occasion.
0:27:26 > 0:27:31The bear family contains the largest land carnivores found on Earth.
0:27:31 > 0:27:34They have a sense of smell that can challenge any animal,
0:27:34 > 0:27:36size, strength, incredible teeth.
0:27:36 > 0:27:39But their diet varies from almost 100% meat in some species
0:27:39 > 0:27:42to plant matter and termites in others.
0:27:42 > 0:27:44They are adaptable and resourceful.
0:27:46 > 0:27:47That's all we've got time for.
0:27:47 > 0:27:50Join us next time as three more pairs of animals
0:27:50 > 0:27:53go head-to-head and we analyse the action, Deadly 360 style.
0:27:58 > 0:28:01Subtitles by Red Bee Media Ltd
0:28:01 > 0:28:04E-mail subtitling@bbc.co.uk