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Mammals are endotherms, meaning they generate their own body heat internally through metabolism....
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AnimalsTranscript
00:29Transcribed by —
00:31Namibia, Southern Africa, a vast dried-up lake bed,
00:56where temperatures can reach almost 50 degrees Celsius.
01:13Overheating is dangerous for all.
01:24Nonetheless, in this cauldron of heat,
01:30mammals have found a way to survive.
01:44Across the planet, mammals have learned how to deal with heat
01:50in the most remarkable ways.
02:10The Serra da Capivara in Brazil.
02:15A world of harsh dry forest.
02:22And scorched cliff faces.
02:29Here, the dry season lasts for up to seven months.
02:37And what little rain that falls, quickly disappears.
02:43Despite this, one mammal has made it home.
02:49A family of bearded capuchins.
03:02They have spent the night high up on the cliff faces,
03:07safe from any predators below.
03:12It may be early, but already temperatures are beginning to soar.
03:19The troop needs to find water.
03:25And none need it more than a mother.
03:30Without it, she won't be able to produce the milk essential for her young baby.
03:37But first, they must make the treacherous journey down to the forest floor.
03:57The new bomb must hold on tight.
04:06Others forge ahead.
04:09Others forge ahead.
04:18The new bomb must be made.
04:23The new bomb must be done by what's removed from the forest.
04:28For the first to reach the forest floor,
04:34the last few cashew fruit provide some welcome space.
04:45But there's not enough to go around.
04:50Mother and baby must go without.
04:56At nearly 40 degrees, the heat is relentless.
05:10Desperate, the troop look for anything that might contain water.
05:31Could the trees provide the solution?
05:43Hidden in some trunks, there is a little water left over from the last rains.
05:56But reaching it is a real monkey puzzle.
06:06Mammals, however, are experts at solving problems.
06:13An older male tries a different approach.
06:22Perhaps a bit more brains and a little less brawn.
06:38A stick produces a dribble of success.
06:46Having watched all the others try, the mother finally gets her turn.
06:53I hope, don't I play a lot of fun.
06:54Please please take care of yourself.
07:09I can't take care of them.
07:13Please take care of your family.
07:14Please take care of yourself.
07:14I'm taking care of your family.
07:15I'm taking care of my family and I'm taking care of my family.
07:30Her tail acts like a sponge, soaking up any water that has collected in the trunk.
07:42Being able to tap these hidden wells is more than just a clever trick.
07:49It's a life-saving lesson.
07:53And one the rest of her family quickly learn.
08:02Their ability to solve such problems will help the troop survive these long, hot, dry months.
08:15And finally, the newborn can get a much-needed drink of its own.
08:31But there are places that are even hotter and even drier.
08:41Australia, the driest inhabited continent on Earth with almost a million square miles of desert.
08:53A furnace where water is almost impossible to find.
09:09An Arabian camel.
09:13Introduced in the 1800s by early explorers,
09:17it's estimated that as many as one million now roam the outback.
09:30For this lone male in search of a mate, desert plants provide a few slim pickings.
09:40Any surplus nutrients can be stored in his most famous feature.
09:48His hump.
09:50Full of fat.
09:52It's a built-in energy store that can be tapped when needed.
10:01And as long as he can find food, he can go without drinking for months.
10:29First place.
10:31At last.
10:32What he has been looking for.
10:38A herd of females.
10:56It's important that he makes a good first impression.
11:07And he has a special way of doing so.
11:12With a doula.
11:24This inflatable sack is unique to camels.
11:29And accompanied by loud gurgling.
11:33Is his way of attracting females.
11:52Has he done enough to impress?
12:01Apparently not.
12:02The raised tail is a polite way of saying no thank you.
12:12Not so easy after all.
12:18Could she be the one?
12:29Looking good.
12:39Bad luck Romeo.
12:45Despite his best efforts.
12:47It's not been his day.
12:56Camels have overcome the desert's greatest test.
13:01Its lack of water.
13:05But this is not the only challenge faced by mammals.
13:09In hot and arid conditions.
13:13Just as dangerous.
13:15Is the risk of overheating.
13:34Shifaka lemurs.
13:36In one of the hottest and driest places in Madagascar.
13:43The trees provide some shade.
13:46And a little relief from the burning sun.
13:59But with midday temperatures that can exceed 45 degrees.
14:05The heat up here soon becomes unbearable.
14:17Especially for the babies.
14:20The most vulnerable members of the group.
14:32But Shifaka have an unusual and clever way to cool down.
14:42If only they can find the right tree.
15:17And once they have.
15:18And once they have.
15:23They hug it.
15:31The salvadora tree.
15:33Is one of their favorites.
15:41These trees draw up cool water from deep below ground.
15:45So their trunks are a few degrees cooler.
15:49Than everything else around.
15:54At the hottest time of day.
15:57Some embraces can last for over four hours.
16:05And some trees are so popular.
16:08There isn't an inch to spare.
16:16This remarkable behavior.
16:19Was first recorded by scientists.
16:21In 2017.
16:22In 2017.
16:39As the world becomes hotter.
16:41We may see cooling behaviors like this.
16:44Become more and more common.
16:55But some Sifakas have gone one stage further.
17:06They know the best place is within the trunk of the salvadora tree.
17:19Here the temperature can be even cooler.
17:28And that can give real respite from the oven outside.
17:43Shifakas have learned that tree hugging is an effective way to keep cool.
17:52But some mammals face a far more dangerous source of heat than the sun.
18:02The dry eucalyptus forests of Australia.
18:08Home to one of the most bizarre of all mammals.
18:16An echidna.
18:21It's one of the most ancient of mammals.
18:24And it reproduces by laying eggs.
18:35She's out foraging.
18:37Using her highly sensitive nose to look for ants and termites.
18:55To work at its best, her nose has to be kept moist.
18:59And this has led her to developing an unusual skill.
19:05She blows snot bubbles.
19:09As the moisture evaporates, it helps to cool her down.
19:20But this female is not alone.
19:36She can be followed by up to ten or more males.
19:44All vying for her attention.
19:50It's what is known as a love train.
19:54It's what is known as a love train.
20:04And it can run for weeks.
20:14One male has managed to get close.
20:19With such a prickly partner, a gentle touch is needed.
20:27But some romantic liaisons don't last long.
20:30With their sensitive noses, echidnas can detect the early signs of danger.
20:44A bush fire.
20:50Their best chance of safety is to get underground.
21:03Echidnas often go underground to avoid the severe heat of the day.
21:11But they also have to do so to escape the heat of a bush fire.
21:25Between 2019 and 2020, Australia experienced its most catastrophic bush fire season on record.
21:43Over 100,000 square miles, an area larger than the United Kingdom, was devastated.
21:54But in such dangerous conditions, echidna have a remarkable survival skill.
22:04They go into a deep sleep known as a torpor.
22:11It's a form of hibernation, during which their heart rate may slow to only four beats a minute.
22:20Their core body temperature drops.
22:24And they may only take a breath once every three minutes.
22:31By doing this, they can live for days without food or water.
22:54After the fire has passed,
23:00the echidnas begin to emerge.
23:13Not all are unscathed.
23:19Melted spines show that this one has had a close call.
23:32But others show no ill effects.
23:38Their unique adaptations have kept them safe.
23:44But as global temperatures rise, forest fires are becoming more intense and more frequent.
23:56The survival skills of echidnas will become even more crucial.
24:10Going underground to avoid the heat makes obvious sense.
24:15But one mammal does the exact opposite.
24:22Harris's antelope squirrel.
24:30Even during the height of summer, when ground temperatures can exceed 80 degrees Celsius,
24:38he will be out foraging amongst the cactus of the Arizona desert.
24:48By being out now, he avoids competition from other mammals.
24:52But the squirrels don't have it all their own way.
25:02A rattlesnake, which is looking for a rodent-sized meal.
25:17It's a standoff.
25:20To see who can withstand the most heat.
25:28As the ground temperature continues to rise, the squirrel's core temperature reaches 43 degrees Celsius.
25:39That would be fatal for humans and most other animals.
25:47But the squirrels have a clever trick that can quickly reduce their body temperature.
25:56He heat dumps.
26:01By spreading its hot body against the cooler sand in the shade,
26:05A squirrel can rapidly reduce its body temperature down by up to 1 degree a minute.
26:17The rattlesnake simply can't compete.
26:23It has to find shelter to avoid overheating.
26:33With the coast now clear, the squirrel can continue his search for the fruit of the spiny cholla cactus.
26:48But this one has already lost all of its low hanging fruit.
26:54There's only one thing for it.
27:00He will have to clamber up these spine-covered branches.
27:09He must be very cautious.
27:23But this fruit is a stretch too far.
27:32Try again.
27:59But the price of success can be painful.
28:05He has to remove some very sharp spines.
28:13He has to remove some very sharp spines.
28:18A final heat dump before enjoying the fruit of his labor.
28:30This tiny squirrel has found a clever way to deal with the heat.
28:39But when you're nearly six meters tall and weigh almost two tons, it's altogether a much bigger problem.
28:57The Wani Valley on Namibia's skeleton coast.
29:07Home to some of nature's real giants.
29:16Giraffes.
29:25This herd is guarded by a dominant bull.
29:35This herd is guarded by a dominant bull.
29:46They spend much of their day out in the open searching for food.
29:53Their tongues are black with a pigment that acts as a sunblock.
30:08But this is only one of the ways by which a giraffe beats the heat.
30:23It's now about to use another of its heat beating adaptations.
30:33A rival male.
30:42He approaches the females.
30:48The dominant bull moves to intercept.
31:01The bulls square up.
31:16These blows are violent enough to tear skin and break bone.
31:30They're now pushing themselves to the limit.
31:34Their core temperatures are rising to near lethal levels.
31:40The reason they don't overheat is connected to their distinctive skin pattern.
31:47A thermal camera reveals that below each brown spot, there is a dense network of blood vessels.
31:59As the giraffe's body temperatures rise, these blood vessels expand.
32:07Releasing body heat, so enabling them to fight on.
32:17The force of each blow is visible as a white hot slash.
32:41The dominant bull wins, and his rival retreats.
32:59In Trinidad lives a mammal that detects the heat that animals produce, and uses it to guide them to a
33:09drink of their victim's blood.
33:27The white-winged vampire bat.
33:34On the prow for its next victim.
33:58This cockerel is fast asleep.
34:11But the bat must be careful.
34:15Cockerels are light sleepers.
34:23The bite must be delivered with precision.
34:33Heat sensitive receptors enable vampire bats to detect subtle differences in temperature.
34:43So it can pinpoint exactly where the warm blood flows close to the skin.
34:58She bites.
35:06Her saliva contains a powerful anticoagulant known as draculin.
35:12It ensures that the blood continues to flow freely.
35:19This helps her feed quickly and avoids her being noticed.
35:32But blood isn't in fact very nutritious.
35:36So the bats have to drink over half their own body weight in one sitting.
35:42As a result, flight becomes nearly impossible.
35:49But her kidneys are remarkable.
35:53And quickly extract the water from her meal.
35:59So within minutes, she vanishes into the darkness.
36:05Leaving the cockerel none the wiser.
36:16While vampire bats use heat from the blood of their victims to find their meals.
36:21One mammal uses the heat from the sun.
36:27Uganda, in Africa, on the banks of the river Nile.
36:33A troop of baboons has gathered at the end of the long hot dry season.
36:41They're waiting for a very special seasonal opportunity.
36:47It begins with the annual emergence of flying termites.
36:57They provide the baboons with a small but much needed treat.
37:11But the older members of the troop know there is another delicacy to be found here.
37:22One that provides them with a far more nourishing meal.
37:32The Nile crocodile.
37:40She laid her eggs in the warm sand.
37:46The baboons would steal them if they could.
37:54But the crocodile, weighing nearly a quarter of a tonne,
38:00is one of Africa's most formidable predators.
38:03And well able to kill a baboon.
38:10So the utmost caution is required.
38:16Their plan is simple.
38:23They wait.
38:29Whilst the crocodile must stay in the sun, guarding its nest.
38:35The baboons keep their cool in the shade.
38:40Waiting for just the right moment.
38:50The crocodile begins to gape.
38:58It's a way of losing heat.
39:05The sun gets stronger.
39:11But the crocodile stays on guard and risks overheating.
39:29Eventually, it gets so hot that it takes the water to cool down.
39:47But the baboons still do... nothing.
39:54Their waiting game has not yet finished.
40:02There's no sense in over-exerting yourself in the heat.
40:07When you can let hungry monitor lizards do the hard work.
40:34Finally, the moment they have been waiting for.
40:42Now they need to move fast.
40:45The crocodile won't be away for long.
41:10The oppressive heat has allowed the baboons to get the food they want.
41:23But there are few places in Africa where the battle to find food is more demanding than the Etosha salt
41:30plan in Namibia.
41:40As temperatures rise across this vast wilderness, mammals of many kinds are gathering around a shrinking water hole.
41:59For a female jackal, this is a good place to hunt.
42:08But it's almost too crowded.
42:15For a jackal to be successful, it needs to be clever.
42:21Just a ghost in the background.
42:31Some of the largest mammals on Earth dominate the water's edge.
42:43The jackal must bide her time.
43:01She spots possible prey.
43:10She happens bobby!
43:13She spots a man of peoples'
43:19Magic, and moves back toacks himself from the map.
43:21They only have two balls left to dwell on the map.
43:21In the wild, the local, the hunters!
43:48Thirst, however, dominates everything else.
43:53And hunters and hunted drink alongside one another.
44:04Temperatures are still rising.
44:10The drinkers start to quarrel.
44:19And she retreats.
44:26But then, things get even more difficult.
44:36A hyena.
44:44More than capable of killing a jackal.
44:56But driven by hunger and thirst...
45:03...this female holds her ground.
45:18And now can get back to hunting.
45:25This time, she sets her sights on a flock of doves.
45:36And tries a more subtle approach.
45:43Hiding in plain sight.
45:50Lulling the birds into a false sense of security.
46:14She waits for the perfect moment.
46:17She waits for the perfect moment.
46:26But they aren't so easily caught.
46:33Nonetheless...
46:34...she's determined.
47:08Success at last.
47:16Her mate arrives.
47:19And he has brought their hungry pups with him.
47:30With so many mouths to feed...
47:34...she will have to be hunting again soon.
47:43Mammals have an extraordinary ability to find water.
47:50Stay cool.
47:52And use heat to their advantage.
47:57That has enabled them to flourish in some of the harshest...
48:01...and hottest environments on the planet.
48:09But if the world is indeed to become even hotter...
48:13...as is predicted...
48:16...then the challenges facing mammals...
48:19...will become greater...
48:20...than they have ever been.
48:38In Madagascar, the Mammals team hope to be the first...
48:41...to film some recently discovered behavior.
48:46Shifak lemur's tree-hugging.
48:50But to get there...
48:51...it's a three-day drive over rough terrain.
48:56A little too much for producer Rob Pilly.
49:11Happy to be back on terra firma...
49:13...the team set off on foot...
49:15...through the spiny forest.
49:18They've joined forces with local scientists...
49:21...from the ESSA research group.
49:24And thanks to their expertise...
49:27...it doesn't take long to find the Shifakha.
49:35They're a little weary of humans...
49:37...so we have to go really slowly...
49:39...approach them slowly.
49:40They're quite skittish.
49:44The Shifakha are much more nimble...
49:46...moving through the forest...
49:48...than the crew carrying bulky kit.
49:52Keeping up with the troop...
49:53...is not without its snacks.
49:56Everything is out to get you.
49:57It's just this giant...
49:58...cactus forest.
50:00They are everywhere.
50:01The spines.
50:03And the dense scrub...
50:05...makes getting any shots a challenge.
50:08Yeah, it kind of makes you...
50:10...almost forced to shoot...
50:12...such high-angle shots...
50:14...when it's so dense...
50:14...because you can't get further back.
50:16I mean, also just maneuvering around the forest...
50:18...it's pretty hectic.
50:20Trying to go quiet...
50:21...even though it's snagging your camera...
50:22...or your lens or a cable or...
50:24...is not easy.
50:28Over the following days...
50:30...the team struggle through the heat...
50:33...with the lemurs...
50:34...giving them the run-around.
50:36We just found a crew...
50:37...and they just disappeared up.
50:39This is going to be a marathon...
50:41...not a sprint.
50:42Lemurs behaving badly.
50:51As temperatures rise...
50:53...the lemurs finally seem to settle.
51:02This could be a breakthrough for the team.
51:05Stewie's up front.
51:07It's just possible...
51:09...that we have found...
51:11...a perfect...
51:12...tree-hugging group.
51:17Fingers crossed.
51:23Not this time.
51:26He's been given the run-around all morning...
51:28...by these lemurs.
51:29Starburst every direction...
51:31...couldn't get a single shot.
51:32It's like the worst ever.
51:39Back at camp...
51:41...it's 45 degrees in the shade...
51:45...but Stuart...
51:47...finds a way to cool himself off.
51:49It's good.
51:51Giandre is more worried about the equipment.
51:54We've raised the laptop...
51:55...up on these hard drives...
51:57...getting some cooling.
51:58It's just too hot.
51:59The cameras are melting.
52:00The little metal pins in the camera...
52:02...have literally melted.
52:03It's...
52:04I've never had that on.
52:08Despite the heat...
52:09...the team are forced to work...
52:11...during the hottest part of the day...
52:13...if they want to film this unique...
52:15...tree-hugging behaviour.
52:20But as the lemurs lead them...
52:23...deeper into the forest...
52:24...they notice something is amiss.
52:27In the heart of this protected area...
52:30...there are signs...
52:31...that trees have been felled.
52:36We see for the last two, three years...
52:39...increase in cutting it in the forest...
52:41...and we believe that it's because...
52:44...these people are so desperate...
52:46...and cut these trees for the forage...
52:48...for their animals...
52:49...and then for their daily needs.
52:52With ongoing drought...
52:54...crops are failing...
52:56...and local people are forced...
52:58...to turn to the forest...
52:59...to make ends meet.
53:03Across Madagascar...
53:04...deforestation...
53:06...and the effects of climate change...
53:07...are only making life harder...
53:09...for both wildlife and people.
53:13It's a sobering reminder to the team...
53:16...of the problems faced by these lemurs...
53:18...who are having to adapt...
53:20...to a rapidly changing world.
53:24Back on the trail...
53:26...the team split up...
53:28...to cover more ground.
53:32Now separated...
53:34...the researchers have a special way...
53:35...to keep in touch.
53:44Using calls similar to the animals...
53:47...lets them maintain a low profile.
53:51...but...
53:51...as they push forward...
53:53...the heat of the day...
53:54...is taking its toll...
53:56...on J. Andre and Rob.
53:58We all just have to stop for a bit...
54:00...have a breather.
54:05And when they start moving again...
54:08...they quickly realise...
54:09...they're lost.
54:10It all looks the same.
54:15I think it's up here.
54:18...but we're not really quite sure...
54:22...where we are.
54:30Woo!
54:46In these conditions...
54:48...it only takes a few hours...
54:49...for heat stroke to set in.
54:51Woo!
54:55Woo!
55:02Yeah, okay, they're ahead.
55:03They're ahead, that's good.
55:05There's a friendly face.
55:09So nice to see you.
55:13Quickly, things can go really pear-shaped...
55:15...unless you're on your game, so...
55:17...a lesson learnt, definitely.
55:21Despite this close call...
55:23...the team are determined to continue.
55:28It's the hottest day so far...
55:31...which should work in their favour.
55:43At last, they find a group...
55:45...that is settling.
55:47Yeah.
55:56Lemur's only tree hug...
55:58...in the hottest conditions.
56:01All the crew can do now...
56:04...is wait.
56:26...and, we're gonna do...
56:34...watch the bridge.
56:34I'm pretty surprised.
56:44Finally, what they came for.
57:00Thanks to the work of this research team,
57:04the efforts to protect the Shifaka's home will continue.
57:09With the education and working together at different levels,
57:15from locals to national to international levels,
57:18for common goals,
57:20then I'll be very optimistic about the future of Madagascar.
57:29Next time, forests,
57:33where we discover how nearly three-quarters of all mammal species
57:38have made their home in this,
57:42the richest and most diverse habitat on Earth.
57:58Cast off and take a grand tour of Scotland's rivers.
58:01From source to sea, press red to set sail on iPlayer.
58:04And over on BBC2, wanderlust sufferers beware.
58:08Simon Reeves sends a postcard from Greece.
58:10Join him there right now.
58:12Or stay with us on one for Antiques Roadshow
58:14at the Ulster Folk Museum.
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