- 1 week ago
Mammals are endotherms, meaning they generate their own body heat internally through metabolism....
温血动物（也称为内温动物）是一类种类繁多的动物——其中包括哺乳动物——它们具有调节自身体温的能力。
温血动物（也称为内温动物）是一类种类繁多的动物——其中包括哺乳动物——它们具有调节自身体温的能力。
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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.
04:09One, two, three.
04:18Theatas
04:19One, three!
04:28For the first to reach the forest floor,
04:34one, three!
04:38One, three!
04:38sustenance but there's not enough to go around mother 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
06:49The mother finally gets her turn
06:57The secondary crunches
06:57The only one who doesn't know
07:02It is going to be the same
07:05So cute
07:09Theordu desire
07:09I would never wish you
07:09I would never wish you
07:09To fix this
07:12I would never wish you
07:12The first week
07:12I was going to do
07:13I don't want to die
07:17I am still not sure
07:30Her tail acts like a sponge, soaking up any water that has collected in the trunk.
07:41Being 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, it'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.
10:31At last.
10:33What he has been looking for.
10:35What he has been looking for.
10:36At last.
10:37No.
10:38A herd of females.
10:55It's important that he makes a good first impression.
10:59But yet.
11:07and he has a special way of doing so with a doula this inflatable sack is
11:27unique to camels, and accompanied by loud gurgling, is his way of attracting females has he done enough to impress
12:01apparently not, the raised tail is a polite way of saying no thank you
12:12not so easy after all
12:18could she be the one
12:28looking good
12:39bad luck romeo
12:45despite his best efforts, it's not been his day
12:56camels have overcome the desert's greatest test
13:00its lack of water
13:05but this is not the only challenge faced by mammals in hot and arid conditions
13:13just as dangerous is the risk of overheating
13:34shifaka lemurs in one of the hottest and driest places in madagascar
13:43the trees provide some shade and a little relief from the burning sun
13:58but with midday temperatures that can exceed 45 degrees the heat up here soon becomes unbearable
14:17especially for the babies
14:19the 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
14:46the right tree
14:46the right tree
14:47the right tree
15:16And once they have, they hug it.
15:30The salvadora tree is one of their favorites.
15:40These trees draw up cool water from deep below ground.
15:45So their trunks are a few degrees cooler than everything else around.
15:54At the hottest time of day, some embraces can last for over four hours.
16:05And some trees are so popular, there isn't an inch to spare.
16:16This remarkable behavior was first recorded by scientists in 2017.
16:38As the world becomes hotter, we may see cooling behaviors like this become 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.
17:43Sifakas 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.
18:07Home to one of the most bizarre of all mammals.
18:16An echidna.
18:21It's one of the most ancient of mammals and reproduces by laying eggs.
18:35She's out foraging, using 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.
20:04And it can run for weeks.
20:14One male has managed to get close.
20:17One male has managed to get close.
20:19With such a prickly partner, a gentle touch is needed.
20:26But some romantic liaisons don't last long.
20:31With their sensitive noses, echidnas can detect the early signs of danger.
20:44A bushfire.
20:51Their 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 bushfire.
21:24Between 2019 and 2020, Australia experienced its most catastrophic bushfire 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.
22:03They 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 4 beats a minute.
22:20Their core body temperature drops.
22:24And they may only take a breath once every 3 minutes.
22:31By doing this, they can live for days without food or water.
22:54After the fire has passed, the echidnas begin to emerge.
23:13Not all are unscathed.
23:18Melted 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 one 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.
26:55There's only one thing for it.
27:01He will have to clamber up these spine-covered branches.
27:08He must be very cautious.
27:11He must be very cautious.
27:23But this fruit is a stretch too far.
27:32Try again.
27:34Try again.
27:59But the price of success can be painful.
28:05Try again.
28:06He 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 Hwanib Valley on Namibia's skeleton coast.
29:02The Hwanib Valley on Namibia's skeleton coast.
29:15The Hwanib land.
29:17The Hwanib Valley on Mon nationally.
29:24The Hgot of acordo with sharks—
29:46They spend much of their day out in the open searching for food.
29:54Their 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, a rival male.
30:41He approaches the females.
30:48The dominant bull moves to intercept.
31:00The 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, releasing 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 on the prowl 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.
35:07Her 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 extracts 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, one mammal
36:22uses 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.
37:47The baboons would steal them if they could.
37:54But the crocodile, weighing nearly a quarter of a tonne, is one of Africa's most formidable predators.
38:03And well able to kill a baboon.
38:09So 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.
39:04The 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.
39:55Their 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...
41:27...is more demanding than the Etosha salt plan in Namibia.
41:40As temperatures rise across this vast wilderness...
41:44...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.
42:44The jackal must bide her time.
43:01The jackal must bide her time.
43:10The jackal must bide her time back after the shackle with etiquette's net forward.
43:17But it has so many towers whichrols come with怎麼了 life loaded.
43:18The night can drag and gaffes it out as it's been��.
43:21The birds may not bide her time as it'll do timing...
43:21But you can't go there.
43:24The scendiands as they are kill.
43:27It's w��� as it's been sauves.
43:29The distance was never to miss her.
43:48Thirst, however, dominates everything else,
43:53and hunters and hunted drink alongside one another.
44:04Temperatures are still rising, the drinkers start to quarrel and she retreats.
44:27But then, things get even more difficult.
44:36A hyena, more than capable of killing a jackal.
44:56But driven by hunger and thirst, 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, and 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.
46:26But they aren't so easily caught.
46:33Nonetheless, she's determined.
47:05Lulling the birds into a false sense of security.
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,
47:33he will have to be hunting again soon.
47:43Mammals have an extraordinary ability to find water,
47:49stay cool,
47:52and use heat to their advantage.
47:57That has enabled them to flourish
47:59in some of the harshest and hottest environments on the planet.
48:09But if the world is indeed to become even hotter,
48:13as is predicted,
48:15then the challenges facing mammals
48:18will become greater than they have ever been.
48:38In Madagascar, the Mammals team hoped to be the first to film some recently discovered behavior.
48:46Shifak Lemur's tree-hugging.
48:50But to get there,
48:51it'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,
49:13the team set off on foot through the spiny forest.
49:18They've joined forces with local scientists from the ESSA research group.
49:25And thanks to their expertise,
49:27it doesn't take long to find the Shifakha.
49:35They're a little weary of humans,
49:37so we have to go really slowly, approach them slowly.
49:39They're quiet skittish.
49:44The Shifakha are much more nimble moving through the forest
49:48than the crew carrying bulky kit.
49:52Keeping up with the troop is not without its snacks.
49:55Ah, everything is out to get you.
49:57It's just this giant cactus forest.
50:00They are everywhere, the spines.
50:03And the dense scrub makes getting any shots a challenge.
50:08Yeah, it kind of makes you almost forced to shoot
50:12such high-angle shots when it's so dense
50:14because you can't get further back.
50:16I mean, also just maneuvering around the forest,
50:18it's pretty hectic.
50:20Trying to go quiet even though it's snagging your camera
50:22or your lens or a cable is, er, not easy.
50:28Over the following days,
50:30the team struggle through the heat,
50:33with the lemurs giving them the runaround.
50:35We just found a group and it just disappeared up.
50:39This is going to be a marathon, not a sprint.
50:42Lemurs behaving badly.
50:52As temperatures rise, 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 that we have found
51:10a perfect tree-hugging group.
51:17Fingers crossed.
51:23Not this time.
51:26It's been given the runaround all morning by these lemurs.
51:29Starburst every direction, couldn't get a single shot.
51:32It was like the worst day ever.
51:39Back at camp, it's 45 degrees in the shade.
51:45But Stuart finds a way to cool himself off.
51:49Whew!
51:51Deandre is more worried about the equipment.
51:54We've raised the laptop up on these hard drives,
51:56getting some cooling.
51:58It's just too hot.
51:59The cameras are melting.
52:00The little metal pins in the camera have literally melted.
52:03I've never had that on.
52:08Despite the heat,
52:09the team are forced to work during the hottest part of the day
52:13if they want to film this unique tree-hugging behaviour.
52:20But as the lemurs lead them deeper into the forest,
52:24they notice something is amiss.
52:27In the heart of this protected area,
52:30there are signs that trees have been felled.
52:36We see for the last two, three years,
52:39increasing continuity in the forest,
52:41and we believe that it's because these people are so desperate
52:46and cut these trees for the forest, for their animals,
52:49and then for their daily needs.
52:52With ongoing drought, crops are failing
52:56and local people are forced to turn to the forest to make ends meet.
53:03Across Madagascar,
53:05deforestation and the effects of climate change
53:07are only making life harder for both wildlife and people.
53:13It's a sobering reminder to the team
53:15of the problems faced by these lemurs
53:18who are having to adapt to a rapidly changing world.
53:24Back on the trail,
53:26the team split up to cover more ground.
53:32Now separated,
53:34the researchers have a special way to keep in touch.
53:44Using calls similar to the animals lets them maintain a low profile.
53:51But as they push forward,
53:53the heat of the day is taking its toll on J. Andre and Rob.
53:58We all just have to stop for a bit.
54:01Have a breather.
54:05And when they start moving again,
54:08they quickly realise they're lost.
54:10It all looks the same.
54:15I think it's up here.
54:19We're not really quite sure
54:20that's where we are.
54:30Woo!
54:39Ow.
54:46In these conditions,
54:47it only takes a few hours for heat stroke to set in.
54:51Woo!
54:56Woo!
55:02Yeah, okay, they're ahead. They're ahead. That's good.
55:05That is a friendly face.
55:06Hey, Nafa.
55:08So nice to see you.
55:13Quickly, things can go really pear-shaped
55:15unless you're on your game, so...
55:17a lesson learned, definitely.
55:21Despite this close call,
55:23the team are determined to continue.
55:28It's the hottest day so far,
55:31which should work in their favour.
55:43at last, they find a group that is settling.
55:48Yeah.
55:56Lemus only tree hug in the hottest conditions.
56:01All the crew can do now is wait.
56:07It's the current.
56:20It's the huge energy.
56:22It's the same thing.
56:23It's almost all the students...
56:24as they drive.
56:24They're not going to be back.
56:25It's a huge!
56:25They're gonna be honest.
56:25They're gonna be careful.
56:25A lot of people make an animal.
56:26They're gonna be brown.
56:26You know, they're not going to be brown.
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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