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00:30Antarctica, the Earth's coldest continent, the one that is most hostile to life.
00:44Here, 1,300 kilometres from the South Pole, it's 40 degrees below zero.
00:54Of all the millions of species of animals on Earth, only one can live here permanently.
01:10A Weddell seal.
01:16She can survive because she can dive below the ice.
01:25Here she is protected from the storms above, and here too, she can find food.
01:50But she is a mammal, and she has to breathe air.
01:55So she has to keep a lifeline open to the world above the ice.
02:01Not only for her, but now for her newborn pup.
02:10She is less than a week old and still very vulnerable.
02:25A blizzard blows in, and with it, storm-force winds.
02:29It could last for a week.
02:42Being mammals, seals can generate heat within their bodies, and their fur, with a thick
02:48layer of fat beneath it, prevents most of that heat from escaping, even in cold conditions
02:53like this.
03:01What is more, she is able to feed her youngster with that mammalian speciality, milk.
03:09And while she does so, she shields him from the worst of the blizzard.
03:38She has worked hard throughout the winter to prevent her breathing hole in the ice from
03:43freezing over.
03:55That requires constant attention, filing back the edges of the hole with her teeth.
04:08Her pup needs to join her under the ice as soon as he can swim properly.
04:17She encourages him to take his first plunge, but, hardly surprisingly, he's not keen.
04:37Now, guided by his mother, he has to learn how to hunt underwater, and to find his way
04:50back through the maze to his hole in the ice.
05:10A warm body, fur, milk, and maternal care are essential for the Weddell seal's survival
05:17in this freezing environment.
05:22And those qualities have helped the mammals to colonize the entire globe.
05:38Equatorial East Africa.
05:42It's hard to imagine a place more different from Antarctica.
05:48To survive here, mammals need additional talents.
05:55This tree shelters the territory of a tiny mammal that spends its whole life in frenzied
06:01activity.
06:05It used to be called an elephant shrew, but now it's called by its African name of sengi.
06:17This is a female rufous sengi.
06:23And like all sengis, she's so active she's permanently hungry.
06:30To get all the food she needs, she has to be both industrious and ingenious.
06:42She has made an intricate network of trails that enable her to hunt her insect prey very
06:48efficiently.
06:51These pathways have another important function when she meets her enemies.
07:21Having a map of these trails in her head can mean the difference between life and death.
07:44Like most mammals, and unlike reptiles, her legs are directly beneath her body.
07:51That makes her less stable, but much faster and more agile.
08:13Not only has she outrun this reptile, she's outwitted him.
08:20And just as well, for she is a mother and has a youngster to care for.
08:38The sengi relies on speed and cunning for its success.
08:43Other mammals have very different techniques.
08:54Here in Madagascar, one of the most bizarre of all mammals is on the prowl.
09:08The aye-aye, like the sengi, lives on insects.
09:13But the ones that she seeks, she can't see, for they're buried deep inside branches.
09:18They're beetle grubs.
09:25To find them, she has a special talent.
09:28She taps her fingers on the wood up to eight times a second and listens for the tiny change
09:33in resonance that indicates a hollow spot within.
09:38Her hearing is so acute, she can identify the precise position in which to gnaw a hole
09:44in order to reach the grub.
09:49And she has a grotesquely long middle finger with which to skewer it.
10:06It takes a young aye-aye four years to perfect this technique, but once it has done so, it
10:13can collect prey that no other mammal can reach.
10:36The Arctic tundra.
10:38Food is hard to find here too.
10:40Indeed, this land is so barren that few large animals can live here.
10:48Yet one mammal has found a way to do so.
11:03It's late spring, and as the mounting strength of the sun warms the land, eight million reindeer
11:10move north.
11:23But the vegetation is so meagre that the only way the herds can get enough is to keep constantly
11:29on the move.
11:37Newborn calves soon discover that they will have to spend every day walking in search
11:43of food.
11:46They have extraordinary endurance.
11:49Some of these animals, before they die, will have trekked for a distance equivalent to
11:54three times around the earth.
12:01Grazing is now at its best, but this is also the time when the reindeer's worst enemy appears.
12:09Biting flies.
12:13The flies not only drive them to distraction, but they can drain a pint of blood each day.
12:31But the reindeer have a defensive strategy.
12:39Each individual tries to push its way into the centre of a group where there are fewer
12:45flies.
13:02With all this pushing and jostling, mothers need to keep their calves close.
13:15Sometimes the flies become so bad that the reindeer can stand them no longer, and they
13:20boat to higher ground where the flies can't follow.
14:19But the price of escape can be high.
14:25In the rush, one mother has lost her calf.
14:49Others have already found it.
15:10The herd has long since moved on, but her maternal instinct is so strong she'll stay
15:16to search for her missing calf for days.
15:23The reindeer are free from flies for now, but with no food on these high slopes, they
15:29will eventually be forced to descend to find new pastures and face the biting swarms once
15:36more.
15:41No animal makes a longer migration across the lands of the earth than these mammals.
15:54Other mammals have found a more economic way of travelling huge distances, and at greater
16:01speed.
16:02They go by air.
16:32Giant, straw-coloured fruit bats inhabit the great forests of the Congo.
16:43Their wings are nearly a metre across.
16:52In late October every year, they set off on a long journey across the forest canopy.
17:02The flocks of hundreds become thousands.
17:13And tens of thousands become hundreds of thousands.
17:20They're fast and powerful flyers, and can travel more than a thousand kilometres in
17:26just a few nights.
17:36How they know where and when to travel is a mystery, but they all end up in one place.
17:42Kasanka, a remote swamp in Zambia.
17:54There are 10 million of them here.
18:10They crowd together in just one small patch of forest, no bigger than two or three football
18:15pitches.
18:16And here they take up residence for a few weeks.
18:20It's the largest fruit bat roost on earth.
18:37After their long journey, they need to rest and relax.
18:50The roost is so crowded that complete strangers rub shoulders and even snuggle up together.
19:01As evening approaches, they prepare to reap the reward for their long journey.
19:20They've come from all over Central Africa to this one place because here, at this time
19:25of year, there is an extraordinary glut of mangoes and other fruit.
19:32Streaming out from the roost, they set off to collect it.
19:50Each bat guzzles at least two kilos worth of fruit every night.
20:08In just a few weeks, this mega-roost will devour more than a billion separate fruits.
20:18It's only the power of flight that allows these mammals to travel so far and so fast
20:24that they can reap such a brief harvest.
20:28After six weeks, the group is ready to go.
20:32After six weeks, the trees have been stripped of their fruit.
20:36Then, once again, the immense aerial armada takes to the air, each bat returning to its
20:43own particular patch of the vast Congo forests.
21:32The land mammals of Africa also travel together in stupendous numbers.
21:40The herds that graze the East African plains are not nearly the size they were a century
21:45ago, but they are still immense.
21:52Grazing together is a good defence. There's safety in numbers.
21:57But hunting together also brings advantages.
22:02This hyena, however, is searching for food on her own.
22:14She needs to be careful.
22:23But she smells food, and she takes risks.
22:32She takes risks.
22:36She takes risks.
22:40She takes risks.
22:44She takes risks.
22:48She takes risks.
22:52She takes risks.
22:56She takes risks.
23:00She takes risks.
23:04She takes risks.
23:08She takes risks.
23:12She takes risks.
23:16She takes risks.
23:20She takes risks.
23:24She takes risks.
23:27She takes risks.
23:33Bruised and bloodied, she is lucky to have survived her mistake.
23:43But she's not totally defeated. She belongs to a clan.
23:48A call to arms rings out through the night.
23:57Reinforcements assemble.
24:07Every adult in the clan responds.
24:18If a clan attack together, they have a chance of challenging the lions.
24:27It's a clan against the pride, each at full strength.
24:35And the clan outnumbers the pride.
24:40It's a clan against the pride, each at full strength.
24:47And the clan outnumbers the pride.
25:10And the clan outnumbers the pride.
25:26The combined power of the hyenas eventually forces the lions to retreat.
25:34Attacking as a coherent team requires a high degree of social cooperation.
25:40And that is another of the mammal's specialities.
25:55Social bonds between mammals begin when mothers feed their young on milk.
26:02And few look after their young with greater care than the mammal which dominates this landscape.
26:10A female polar bear is trying to find food for her cubs.
26:18But this is a particularly difficult time of the year.
26:23The sea ice on which she hunts is melting beneath her feet.
26:29She must look for food on land.
26:40She must look for food on land.
27:06They're all safely ashore.
27:09But they would still face months of hunger.
27:13Finding food is not so easy on this cold and barren coast.
27:18The search may be a long one.
27:27Polar bears have an extraordinarily sensitive sense of smell.
27:33And she has caught a faint whiff of something promising.
27:39A whale.
27:48It's the immense carcass of a bowhead whale.
27:55A whale carcass could provide more than any one family could eat.
28:03But they're not the first here to find it, by any means.
28:09The smell has brought in bears from miles away.
28:18Bear families seldom get on with one another.
28:32She's taking a risk bringing her cubs here.
28:37Male bears can and do kill and eat small cubs.
28:49Another family challenges her.
29:01She must decide whether to compete for food or not.
29:05Whether to compete for food or run away and go hungry.
29:17She keeps her cubs close to her and stands her ground.
29:22Their mother's courage has won the cubs a meal.
29:27Their mother's courage has won the cubs a meal.
29:31Their mother's courage has won the cubs a meal.
30:01Living as a family may bring rewards, but it can also create problems,
30:06for siblings can also become rivals.
30:13A coati, a South American relative of the raccoon.
30:23These babies were born in a nest high in a tree
30:26and are about to come down to the ground.
30:30They're about to come down to the ground for the first time.
30:38Some more reluctantly than others.
31:00Once on the ground, the mother coati rounds her babies up
31:04and takes them away to join a single large group.
31:12Together these families form a gang up to 40 strong.
31:23Once again, numbers bring safety.
31:26The first to spot danger will warn everyone.
31:42But keeping order isn't easy and when they find food, it's a free for all.
31:56Meerkats in the Kalahari Desert also live in large groups,
32:00but they're rather more organised.
32:05Meerkats in the Kalahari Desert also live in large groups,
32:09but they're rather more organised.
32:35Each family band is controlled by a queen,
32:38who is nearly always the only female to breed.
32:45She has been kept very busy suckling her five pups
32:49and it's high time they became more independent.
32:55Today is the new brood's first trip to get breakfast for themselves.
33:05It takes weeks for youngsters to learn how to find food.
33:17This one is trying to catch ants,
33:21but hasn't quite grasped the necessary technique.
33:29But this youngster has persuaded other youngsters
33:34to show him what to do.
33:38The tutor is not his parent, just an enthusiastic instructor
33:42and one who will adapt his lessons to the ability of his student.
33:50This new one is a beginner, so he starts with something easy,
33:54how to dig for insect larvae.
34:04Other meals, like this one, are much trickier.
34:08So the tutor disables the scorpion's sting
34:12before he lets the youngster tackle it.
34:16The family also co-operates in defence.
34:20Every member does a tour of guard duty,
34:24keeping an eye out for danger.
34:28The youngster is the only one who can be seen
34:32and the tutor is the only one who can be seen.
34:38The youngster is the only one who can be seen
34:43Every member does a tour of guard duty, keeping an eye out for danger.
34:47So while one watches, everyone else can rest.
34:59And on warm days, one can easily nod off.
35:13The secret of Meerkat's success
35:17is that everyone takes a turn in communal duties.
35:21The secret of Meerkat's success
35:25is that everyone takes a turn in communal duties.
35:30The secret of Meerkat's success
35:34is that everyone takes a turn in communal duties.
35:39The secret of Meerkat's success
35:43is that everyone takes a turn in communal duties.
35:56But many mammals do more than just share their workload.
36:00Some can share their knowledge
36:04and do so across several generations.
36:09Elephant survival depends on profiting
36:13from the experience of many lifetimes.
36:19This baby elephant was born last night
36:23and the whole herd seems to welcome this new addition.
36:29But the mother is young and inexperienced.
36:33This is her first baby.
36:39This is her first baby.
36:54If she is to produce milk, a mother must drink
36:58and the newborn calf must keep up with her
37:02as the herd continues on their long journey to find water.
37:06After eight kilometers, the calf is flagging.
37:14Enough is enough.
37:24The young mother encourages her calf to continue
37:28but there is still a long way to go
37:33and the calf is already getting dehydrated.
37:37The calf is tired.
38:01The elephants are now so close to water
38:06that they can smell it.
38:11Water at last.
38:15Water at last.
38:39Water at last.
38:45Water at last.
38:55This is the calf's first encounter with a waterhole.
39:01She's not sure what to make of it or, indeed, how to get out of it.
39:06Her mother tries to help her
39:10but she has no experience of dealing with babies.
39:24As the herd moves deeper into the swamp,
39:28the calf follows but now she is in real trouble.
39:36Elephant babies can and do
39:40get permanently stuck in deep mud.
39:44Her mother's attempt to save the calf
39:48has been a failure.
39:56The calf is now trapped in the mud
40:00and she can't get out of it.
40:05Her mother's attempts to help her baby
40:09are only making matters worse.
40:13It's stuck beneath her
40:17and she's pushing it deeper still.
40:21But now the baby's grandmother spots the problem
40:25and steps in.
40:30Drastic action.
40:34She pushes mother out of the way
40:38with an unceremonious poke in the rump
40:42and enables her granddaughter to scramble free.
40:52Mother and calf have learned a valuable lesson
40:56from grandma.
41:00Such passing of wisdom across generations
41:04has been an important element in the survival of elephants.
41:09The largest animal on land, the elephant,
41:13is a mammal.
41:17And so are the largest animals in the sea.
41:25The elephant is the largest animal
41:29in the world.
41:33And so are the largest animals in the sea.
41:49A female humpback whale
41:53and her calf.
41:57Every few years she will travel nearly 5,000 kilometres
42:01from the rich waters of the Antarctic
42:05to these warm but comparatively sterile waters of the Pacific
42:09to give birth to a single calf.
42:32The seas around Tonka
42:36are not only a nursery for humpbacks
42:40but also their mating ground.
42:54This 50-year-old female
42:59has come here to seek the best partner
43:03and she starts by announcing her arrival to potential suitors.
43:29One by one, the males arrive.
43:45But as they do, she swims away
43:49compelling her half a dozen or so suitors to follow her.
43:59She leads
44:03while the males jockey for position behind her.
44:09The males bellow threats to one another
44:13creating huge plumes of bubbles.
44:18So far, it has been a relatively gentle affair.
44:22Now, the competition becomes serious.
44:28Hour after hour, the males battle for position right behind her.
44:33And now, the competition becomes serious.
44:39Hour after hour, the males battle for position right behind her.
45:02And now, the 40-ton males begin to smash into one another.
45:33This is the most massive battle in all of nature.
45:37Rival males can kill one another.
45:49As the conflict reaches its climax
45:53they try to force each other downwards.
46:03At last, a victor
46:07takes his place alongside the female
46:11and remains unchallenged.
46:15By inciting the males to fight
46:19the female has secured the best mate for herself.
46:23The one who will be her best mate.
46:27The female has secured the best mate for herself.
46:31The one who is most likely to father the strongest offspring.
46:48Together, the couple dive to the depths.
46:52But still, no one knows where they will mate.
46:57They are left to fend for themselves.
47:01All mammals, including ourselves,
47:05share a set of winning characteristics.
47:09The male is the strongest.
47:13The female is the weakest.
47:17The male is the strongest.
47:21The female is the weakest.
47:25The male is the strongest.
47:29They all share winning characteristics.
47:37Warm bodies, extraordinary senses
47:41and highly developed intelligence.
47:45And those qualities have contributed to their and our success.
47:54But perhaps the most important characteristic of all
47:58is the birth of our family ties.
48:04It is the mammal family that has conquered the earth.
48:29Tonga is famous for humpback whales,
48:33but even here, finding and filming whales in the open ocean
48:37would prove challenging.
48:41For the life team, capturing the humpback whales' unique mating contest,
48:45known as a heat run, would need local knowledge,
48:49hours of experience and a keen eye.
48:53We've heard that one of the boats further inland by submarine rock
48:57has seen a female with a calf and an escort,
49:01which is something which might build to hopefully a heat run.
49:05So we're going to head over there and take a look.
49:09Any adult female with a calf could be coming into season
49:13and so might be a target for amorous males.
49:17When we got there I was pretty excited, a little bit nervous.
49:21Didn't know what to expect.
49:25Once I got in the water and dived down, it was surprisingly quiet and mellow.
49:33Certainly didn't expect what happened next.
49:37The calf just came straight up towards me.
49:41The calf just came straight up towards me.
50:12She seemed really relaxed and definitely interested in me.
50:23It's literally just swimming around within metres of flicking its tail,
50:27just being inquisitive I think and having a bit of fun.
50:36It's obviously quite young so it's staying on the surface quite a long time.
50:40It's not diving down for very long, maybe a couple of minutes.
50:44The mother will be about five or ten metres below, just keeping an eye on it.
50:57But even a calf has great power in its fins and tail.
51:01Roger will need to be careful.
51:10Got it?
51:14Got it?
51:18That was the most silly thing I've ever seen in my life.
51:22It's just gambling around like a little newborn lamb.
51:26It weighs two tonnes.
51:30A couple of bumps just come around and flash fluke at me or whatever.
51:34I've got a great shot of it chasing Jason around.
51:38It's just backpedalling like this.
51:42It's just a baby, like a little puppy.
51:46You're playing with a little puppy but it's four metres long.
51:50It's just ludicrous.
51:54She is just totally chilling out underneath Peck's back,
51:58just hanging like this at about 15 metres.
52:03It's one thing to be close to a playful baby.
52:07It will be another to be in the path of a testosterone-charged group of males,
52:12each ten times her size.
52:20There are enough males here for a heat run,
52:24but are they in the mood?
52:29Yes!
52:33That was pretty good.
52:51These whales can weigh up to 40 tonnes and they move surprisingly quickly.
52:55So as well as getting the cameraman in position to get the shots,
52:59which they have to be fairly close, we have to be really careful that they don't get bumped or hit.
53:03If they get a knock from one of these guys, it can do some serious damage.
53:15To avoid disturbing the whales' behaviour,
53:19the team need to free dive without scuba tanks,
53:23and hold their breath as long as they can.
53:27On a good dive I can hold my breath for maybe two minutes.
53:31These guys, they can go for 20 minutes or more before they have to come up for a breath.
53:35There's no contest.
53:39More and more whales are gathering, but it's not turning into a heat run yet.
53:43I'd have to say what's going on for this.
53:47Was there a fire that time?
53:51They're kind of moving around, coming up and under and over.
53:55Hopefully something's starting to happen.
53:59Maybe love's in the air?
54:07Love may be in the air, but it isn't in the water.
54:11Despite keeping tabs on the whales over the next 10 days,
54:15there was still no sign of a heat run starting.
54:19You'd think it'd be quite easy to keep track of a 40-tonne animal.
54:23We've got six of them out here, and we keep losing them.
54:27One minute they're there, we get up reasonably close,
54:31within 30 seconds they've dived and they're gone again.
54:35Then it takes another maybe five minutes, ten minutes, and then they'll come up again
54:39and they'll be 300 yards away, and it just takes ages to get close to them.
54:43So we're just playing a continuous game of cat and mouse.
54:47Cat and mouse? It's whales.
54:55The mating season is coming to an end, and the crew haven't completed their mission.
54:59But then, at last, the whales' behaviour seems to have changed.
55:03So this is it.
55:07We've just spotted about six or seven humpbacks on the horizon.
55:11We think it's a heat run.
55:13The last 16, 17 days on the water are probably going to come down for the next two hours,
55:17as to whether we get our shots or not.
55:21The chase is on.
55:37There's at least three or four males going past,
55:41and they're all competing and knocking into each other and crossing,
55:45as they try to get the pole position behind the female.
55:49Right at you, right at you.
55:53The whales are moving so fast that to stand any chance of filming them,
55:57the crew needs to be dropped right in front of them.
56:01Just as Roger gets alongside the males,
56:05the tempo of the chase suddenly shifts to full bore with a flick of a tail.
56:09The males are all over the place,
56:13and they're all over the place.
56:17They're all over the place.
56:21They're all over the place.
56:25They're all over the place.
56:29With a flick of a tail.
56:45Facing the charging males deep underwater,
56:49Roger keeps shooting, holding his breath until the group pass over.
56:59A quick gasp of air,
57:03and Roger's back down again.
57:15The whales continue to rush by.
57:19In the end, Roger just can't keep up any longer.
57:23Exhausted,
57:27it's time to return to the boat for the last time.
57:31Amazing. That was the most amazing experience I've ever had.
57:35We had about seven or eight.
57:39We both dived down about 20 metres in front,
57:43and then the female came through first, quite close,
57:47and then they all just started diving towards me,
57:51and I was just standing in a stream of traffic.
57:55One side, one the next side, one the next side,
57:59and then after about 40, 45 seconds I was getting a little bit out of breath,
58:03and then I sort of looked up and there's one sitting right on top of me.
58:07Did you get her? I think so. I hope so.
58:11If not, we're both divided.
58:15It's taken 18 days and hundreds of dives,
58:19but at last the team have been able to reveal a secret of these whales' lives
58:23that few people have ever seen.
58:49NASA Jet Propulsion Laboratory, California Institute of Technology