- 5/10/2025
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TVTranscript
00:30For millions of years, before birds evolved and long before the rise of the mammals, cold-blooded animals ruled the world.
00:51In some places, they still do.
01:00Some of these reptiles witnessed the dinosaurs come and go.
01:10Yet, in all that time, they themselves remained virtually unchanged.
01:16Among them were some of the most impressive reptiles alive today.
01:26They took that most characteristic of reptilian features, the scale, to extremes.
01:32They turned it into armor.
01:34That increased their weight.
01:38But nevertheless, some can still move with extraordinary speed.
01:47And although they may appear cold and impassive, they can nonetheless be passionate.
01:53And even affectionate.
02:04Among them are the biggest of all reptiles alive today.
02:08They're the crocodiles, the turtles, and the tortoises.
02:12This is a giant Galapagos tortoise.
02:23And it's climbed all the way up the flank of this great volcano.
02:28And it's here, wandering around the rim of the crater.
02:32But why should it come to such a bleak and inhospitable place?
02:40Tortoises, being reptiles, can't generate their own body heat internally, as we do.
02:46Instead, they must get it from their surroundings.
02:50And these particular ones have come up here to warm themselves on the hot volcanic rocks
02:55among the jets of steam and sulfurous gas.
02:58They live longer than any other animal on Earth, well over 150 years.
03:09They weigh up to a quarter of a tonne and have shells over a metre across.
03:14They really are giants.
03:16Having a body encased in shell obviously brings problems.
03:30And one of them is how do you mate.
03:33Making love in a suit of armour is not easy.
03:37But the males have a very ingenious solution.
03:40The underside of their shell is concave, so it fits neatly over the domed top of the shell
03:52of the female, who is somewhat smaller.
03:56That doesn't make clambering on top of her any easier, initially.
04:01But once the male is up there, it will reduce his chance of slipping off.
04:05The two shells fit together as neatly as two spoons.
04:24A tortoise's shell is so familiar to us, it's easy to forget what an extraordinary construction
04:47it is, but how did it originate?
04:52Nearly all reptiles are covered in scales, and so were the tortoise's ancestors.
04:58But then, as they evolved, a radical change took place.
05:03The ribs expanded outwards, so that they enclosed the hip and the shoulder joints.
05:14They enlarged and fused with other bones beneath the skin.
05:19They widened, and eventually they joined together to form a bony box.
05:24Above, the scales in the skin enlarged to form a continuous shield of horn on the surface
05:33of the box.
05:35And the basic armour was complete.
05:41By developing a shell, tortoises inevitably sacrifice speed, so they can't sprint off and
05:48take shelter in a crack when danger threatens.
05:51But with a shell like that, they seldom need to.
05:59Some have added deluxe features to the basic model.
06:04This is an eastern box turtle.
06:16In North America, where it lives, there are plenty of would-be predators.
06:21Raccoons among them.
06:24And they have very nimble paws.
06:34But these turtles don't have to worry, because their shell has a special safety feature.
06:41It has a drawbridge.
06:43And when danger threatens, the box turtle just retreats into its shell and pulls it up.
06:59The drawbridge fits so tightly, there is no crack for the raccoon to get its teeth into.
07:04After a while, most raccoons give up.
07:23Of course, when your head is inside your shell, you can't see whether your attacker has gone
07:34or not.
07:35So it's best to check before you emerge fully.
07:38A shell is an excellent defence against predators, but there are other dangers against which it provides
07:50no protection whatever.
07:51It's mid-summer, it's nearly midday, and it's very, very hot.
08:00And as a consequence, I'm sweating.
08:03Sweating is a direct response to heat that only mammals can do.
08:09No reptile like this gopher tortoise has got sweat glands, but instead, it's got another
08:16way of keeping itself cool.
08:20Most reptiles head for the shade when it gets too hot.
08:24To see where this gopher tortoise is heading here in Florida, I'm going to use this.
08:31A remotely controlled mini-camera on wheels with its own lights.
08:36It can go pretty well anywhere.
08:41The gopher tortoise is heading for home.
08:49And with luck, I'll be able to follow it, the tortoise, as it goes down into its burrow.
08:59And that camera has also got a thermometer mounted on it.
09:03Already, I can see the temperature is beginning to drop.
09:10The further down the burrow we go, the cooler it gets.
09:15Now, where's the tortoise?
09:20There it is.
09:21We're now a couple of metres in, but the burrow could go on for some 50 feet, 17 metres.
09:34And it's all been built by this tortoise.
09:37Well, that is not a tortoise.
09:47That's a rattlesnake.
09:51Obviously, taking shelter from the heat, just as the tortoise is.
09:55The tortoise is so well-armoured, it's in no danger from the snake.
10:03And gopher tortoises don't seem to mind sharing their burrows.
10:10Ah!
10:13Changed its mind, and there's its rattle.
10:15Over 100 different species of animal have been recorded taking shelter inside tortoises' tunnels.
10:26In fact, some can live nowhere else.
10:29But there's another reason why tortoises' homes are so popular.
10:34Tortoises are one of the few animals here that can actually dig.
10:43Each may have more than one burrow within its territory,
10:47and that's very valuable,
10:48because they have to deal with an even greater danger than sunstroke.
10:57Bush fires.
11:04These are a major and recurrent threat to all the animals that live here.
11:23Tortoise tunnels are invaluable places in which to take refuge.
11:28Gopher tortoises may seem to be unassuming creatures,
11:44but their engineering skills are essential for the survival of the whole ecosystem.
11:49The ground is still smoking,
11:59but the flames have passed,
12:00and the emergency is over.
12:07So, by digging tunnels,
12:09tortoises save not only their lives,
12:12but the lives of hundreds of other animals.
12:15But tunnels aren't the only place
12:18where you can escape extremes of temperature.
12:21There's another environment that's cooler and even more stable.
12:25Water.
12:31Some of the ancestral tortoises started to spend all their time there
12:36and became turtles.
12:39Some still walk slowly along the bottom
12:49in much the same way as their ancestors walked on land.
12:55Water is a good place for a cold-blooded animal to live.
12:59It retains its warmth through the night
13:01and stays comfortably cool during the heat of the day.
13:04So, turtles are able to keep their body temperature
13:07relatively constant without much difficulty.
13:24Many have developed webs between their toes
13:27and have become very efficient swimmers.
13:36The most aquatic of all freshwater turtles
13:40is found in New Guinea
13:41and a few rivers like this one in northern Australia.
13:47The pig-nosed turtle.
13:49It's feet have become completely transformed into flippers
13:56and are of little use on land.
14:00And indeed, the pig-nosed turtle rarely comes ashore.
14:08But turtles are descended from land-living ancestors
14:12and so they still need to breathe air.
14:14Females also have to return to land
14:27in order to lay their eggs.
14:31Pig-notes nest during the dry season
14:34high up on the riverbank.
14:39If turtle eggs get wet,
14:41the babies inside them will drown.
14:43At least, that is the case with most turtles.
14:48An egg for a turtle
14:50represents a huge investment
14:53as it does for any reptile.
14:55So, turtles go through a great deal of trouble
14:58to make sure that they lay their eggs
15:00in safe, dry places.
15:04So, you would think that dropping one into water
15:06would be a disaster.
15:09But watch.
15:13A fully developed baby turtle.
15:39And it's come from an egg
15:43which, as far as we know,
15:45is unique in the reptile world.
15:47It can not only survive being flooded,
15:50it actually requires to be submerged in water
15:53in order to hatch.
15:54This enables the pig-nose
15:58to make the hatching of its eggs
16:00coincide with the onset of the rainy season.
16:05A view inside the egg
16:07would show the babies
16:08to be fully developed.
16:14They can remain there
16:16in a kind of suspended animation,
16:18if necessary, for weeks.
16:20When the rains finally arrive,
16:33they are torrential.
16:35The river rises swiftly
16:38and soon the nests are flooded.
16:40This would be a disaster
16:54for most turtles,
16:56but the unhatched pig noses
16:58are ready for it.
17:00Indeed, it's the moment
17:02they've been waiting for.
17:03Their unique waiting strategy
17:25ensures that no matter
17:27how late the rains are,
17:28the young turtles only emerge
17:30when the rivers are full
17:31and there's plenty to eat.
17:39They're able to swim immediately.
17:48In due course,
17:49the females among them
17:50will return here
17:51to lay eggs themselves.
17:55The males, however,
17:56will never set foot
17:57on dry land again.
18:01No turtles are better suited
18:04to life in fresh water
18:05than the pig nose.
18:07But the most extreme adaptations
18:09for swimming
18:10are found in those turtles
18:12that went to sea.
18:21Marine turtles
18:22have altered their front legs
18:24really radically
18:25and turned them
18:26into oar-like flippers.
18:28They're so at home
18:33in the sea
18:34they even mate
18:35while swimming.
18:41The male turtle
18:42has special hooks
18:44on his front flippers
18:45that enable him
18:46to cling on
18:46to the female's shell.
18:48And he has to have
18:49a firm grip
18:50for she makes
18:51no allowance for him
18:52as she swims.
18:53But hanging on
18:59to his female
18:59is going to get
19:00much harder
19:01for this male.
19:04A rival
19:05has appeared.
19:09The male's armour
19:11protects most
19:12of his body
19:12but his rear flippers
19:14are exposed
19:15and they
19:16are relatively
19:17soft
19:17and vulnerable.
19:18there can be
19:35little doubt
19:35that this hurts
19:37but there's not much
19:38that the first male
19:39can do about it.
19:41If he lets go
19:42with even a single
19:43flipper
19:43he will lose
19:44his grip
19:45and his female.
19:48The rival tries again
19:55and attacks
19:57the front flipper.
20:11And now
20:13the male's troubles
20:14are about to double.
20:18a second rival
20:19arrives.
20:28The two challengers
20:30join forces
20:31and attack the male
20:33from both sides.
20:44His only option
20:45is to grin
20:46and bear it.
20:52Now
20:52a third hopeful male
20:54joins in.
20:57The female
20:59tries to shake
21:00them off
21:00but there's no
21:01shifting them.
21:02it's going
21:13from bad
21:14to worse
21:15even more males
21:16gang up
21:17on the hapless couple.
21:21Some of the gang
21:22try to force themselves
21:24between the mating pair.
21:25The pair have now
21:36been submerged
21:37for a long time
21:38and both of them
21:39are in desperate need
21:41of a breath.
21:43If the rivals
21:44can prevent the male
21:45from reaching the surface
21:46he will have no choice
21:48but to let go.
21:49He's in real danger
21:50of drowning.
21:51At last
22:06the determined couple
22:08break free
22:08and make a dash
22:10for the surface.
22:11With a welcome
22:20gasp of air
22:21the pair escape.
22:36One by one
22:37the gang
22:38give up.
22:41It was over
22:51200 million years ago
22:53that the first turtles
22:54took to the water
22:55but they were not alone.
22:57Another group of reptiles
22:59were also making
23:00the same move
23:01and they too
23:02were armoured giants.
23:11Crocodilians
23:14like turtles
23:15and tortoises
23:16have barely changed
23:17since the time
23:18of the dinosaurs.
23:27Today
23:28crocodiles
23:29caiman
23:30and alligators
23:31live in tropical waters
23:33throughout the world.
23:34crocodiles
23:38and tortoises
23:39are obviously
23:40very different
23:41but they do have
23:43one thing in common
23:44armour.
23:46Their bodies
23:47are encased
23:48by tough
23:49thick scales
23:50particularly
23:52along the back.
23:54In tortoises
23:55that armour
23:56is clearly
23:57defensive
23:57but for crocodiles
24:00it has
24:01an extra
24:01function.
24:03Just below
24:04each of these scales
24:05lies a network
24:07of blood vessels.
24:09A crocodile
24:10can control
24:11the flow of the blood
24:12within them.
24:13When basking
24:14it allows it
24:15to circulate freely
24:16so transferring
24:18the sun's warmth
24:19from these
24:20ridged scales
24:21to the rest
24:22of its body.
24:22The crocodile
24:24in short
24:25has rows
24:26of very effective
24:27solar panels
24:28all down
24:29its back.
24:33And a
24:34sophisticated
24:35solar heating
24:36system like that
24:37is a very
24:38valuable facility
24:39for a
24:40cold-blooded
24:40creature.
24:48Being
24:49cold-blooded
24:50brings
24:50considerable
24:51advantages
24:52to a crocodile.
24:53Whereas
24:54a warm-blooded
24:55predator
24:55like a lion
24:56would die
24:57if it didn't
24:58feed every few
24:58days
24:59a crocodile
25:00if necessary
25:01can go without
25:01food
25:02for months
25:03on end.
25:04And that
25:05means that
25:05crocodiles
25:06can live
25:06in places
25:07where no
25:08warm-blooded
25:09predator
25:09could survive
25:10and wait
25:12for events
25:13that only
25:13happen
25:14two or three
25:15times
25:15each year.
25:17And one
25:17of those
25:18events will
25:18occur
25:19tonight
25:20right here.
25:22this road
25:25in northern
25:25Australia
25:26is close
25:27to the coast
25:27and it floods
25:28at the highest
25:29tides.
25:37Night
25:38falls
25:38and the scene
25:39changes dramatically.
25:45The road
25:46is now covered
25:47in water
25:48and crocodiles.
25:56But this
25:57is no
25:58random gathering.
26:00The crocodiles
26:00are all here
26:01for a reason.
26:08We know
26:09that some
26:09of them
26:10have traveled
26:10over 60 miles,
26:12a hundred
26:12kilometers
26:13to get here.
26:24But how
26:25they know
26:25when to come
26:26here,
26:27we have
26:27little idea.
26:28there must
26:42be some
26:4340 crocodiles
26:45assembled
26:46in the river
26:47behind me.
26:49And what
26:50makes that
26:50sight all
26:51the more
26:52remarkable
26:52is that
26:53these are
26:54saltwater
26:54crocodiles,
26:56which are
26:56normally
26:56very territorial
26:58and intolerant
26:59of one
27:00another.
27:01So there
27:02must be
27:02something pretty
27:03special happening
27:04in the river
27:05tonight.
27:06And indeed,
27:07there is.
27:08This river
27:09is tidal,
27:11but it's
27:12been crossed
27:12by a barrage.
27:15However,
27:16at particularly
27:17high tides,
27:19the water
27:20flows over
27:21the barrage.
27:23And that
27:23is the moment
27:24that all
27:25these crocodiles
27:26are waiting
27:27for.
27:30With the
27:31saltwater
27:31come fish.
27:34Mullet
27:34have been
27:35waiting for
27:35weeks to
27:36migrate up
27:36the river
27:37to breed.
27:37This high tide
27:38is their
27:39first chance
27:40to cross
27:41the barrage.
27:47And the
27:48crocodiles
27:48are waiting
27:49for them.
27:55remember,
27:59it's now
27:59pitch dark.
28:01Our
28:01infrared cameras
28:02give us
28:03a clear view,
28:04but the
28:04crocodiles can
28:05see virtually
28:06nothing.
28:07So they
28:07wait with
28:08open jaws,
28:09ready to
28:10snap them
28:10shut at the
28:11first touch
28:12of a fish.
28:12normally,
28:31saltwater
28:31crocodiles would
28:32not tolerate
28:33being so close
28:34to each
28:34other.
28:35They do
28:50compete for
28:51the best
28:52fishing spots,
28:53but their
28:53disputes are
28:54settled with
28:55the minimum
28:55of fuss.
28:56The fish
29:12keep coming
29:13for over
29:14an hour,
29:15but as the
29:16tide starts
29:17to fall,
29:18so their
29:19numbers dwindle.
29:26With so
29:27many crocodiles
29:28competing,
29:29some inevitably
29:31go hungry.
29:33But for
29:34those that
29:35stay around,
29:36there will
29:36be a second
29:37bite to
29:38this particular
29:39cherry.
29:44The next
29:45high tide
29:46comes during
29:46the day
29:47and brings
29:48yet more
29:49fish.
29:56The
29:57crocodiles
29:58can now
29:58see the
29:59fish,
29:59but that
30:00doesn't seem
30:00to make
30:01them any
30:01easier to
30:02catch.
30:21These
30:22skillful
30:22hunters
30:23are surely
30:23dramatic proof
30:24that reptiles
30:25are certainly
30:26not
30:27simple-minded
30:27creatures.
30:29They've
30:29predicted the
30:30time of the
30:31arrival of the
30:31fish with
30:32astonishing
30:32accuracy,
30:33and they
30:34have worked
30:34out just
30:35what they
30:35have to
30:36do to
30:36catch them.
30:56up.
30:57They have
30:58managed to
30:59suppress their
31:00normal
31:00antagonism to
31:02one another
31:02so that they
31:03could all
31:04take advantage
31:04of this
31:05bonanza.
31:06the more
31:15the more we
31:16learn about
31:16crocodiles,
31:18the more we
31:18realise what
31:19complex creatures
31:20they are.
31:21the more we
31:32know.
31:33Despite what you
31:34might think,
31:36crocodilians are
31:37among the most
31:37talkative of
31:39reptiles and
31:40amphibians.
31:41Indeed, they're
31:42second only to the
31:43frogs in the
31:44variety of noises
31:45that they make.
31:46the most
31:48impressive sounds
31:49of all come
31:50from the
31:51American
31:51alligator.
31:53When the
31:53breeding season
31:54starts, the
31:55males begin to
31:57proclaim their
31:58ownership of
31:58territories.
32:16the vibrations
32:19in his body
32:19are so powerful
32:20they make the
32:21water dance
32:22along his
32:23back.
32:23sound travels
32:46through water
32:47even better than
32:48it does through
32:48air and he can
32:49be heard by other
32:50alligators hundreds
32:52of metres away.
32:53This is a clear
32:55statement of
32:56ownership of
32:57territory.
33:01That's fine when
33:02he does it lying
33:03in his own patch
33:04but watch what
33:05happens when he
33:06bellows close to
33:08another male.
33:23but the rivals don't
33:43come to blows.
33:44they sort out their
33:46differences with
33:47gestures.
33:50Head slaps and
33:52gaping jaws are
33:53very obvious signals
33:54but alligators also
33:55send messages in
33:57less conspicuous
33:58ways.
33:59Raising their
34:00backs slightly above
34:01the surface of the
34:02water is a
34:03significant move.
34:04It's a claim to
34:05dominance.
34:10Using signals that are
34:12almost imperceptible to
34:13us all these
34:14individuals are sending
34:16messages to each
34:16other making claim
34:18and counterclaim.
34:24Communication between
34:26alligators can be very
34:27subtle and quiet but
34:30there are some occasions
34:31moments when they
34:32really want to make
34:33their meaning very
34:34unambiguously clear.
34:37And one of those is
34:38when they're guarding
34:39their nests as this
34:42one is.
34:55I think that was
34:56pretty clear.
34:59Anyway, I won't
35:01press the point.
35:09Communication between
35:10crocodiles starts even
35:12before they've hatched.
35:20A tranquil pool in
35:21Argentina and in it a
35:24female broad-snouted
35:25caiman.
35:29She laid her eggs in a
35:30pile of vegetation
35:31close to the water
35:32almost three months
35:33ago.
35:34Now, sounds are
35:36coming from it.
35:38The eggs are
35:39beginning to hatch.
35:44Even while the eggs are
35:46still within the nest,
35:47their mother can hear
35:48them from some way
35:49away.
35:50back on the nest, she
36:12listens intently.
36:14Then, very gently, she
36:28starts to take it apart.
36:35She can't know exactly
36:36where each of her babies is
36:38and stops every few seconds
36:40and stops every few seconds
36:40to listen.
36:57At last, the young are free.
36:59babies are free, but she
37:01doesn't abandon them.
37:10She is going to take them down
37:12to the pool that she's selected
37:14as their nursery.
37:15Some babies start to make the
37:22journey for themselves, but they
37:24continue to call, and that helps
37:26their mother locate them.
37:27caiman jaws are among the strongest in the
37:42animal kingdom, but now she uses hers
37:45with the greatest delicacy and gentleness.
37:48So, at last, her babies are brought
38:16together in the nursery pool.
38:18her mother's job is still not finished.
38:32Several of the eggs have failed to
38:34hatch.
38:41One by one, she takes these in her
38:44mouth.
38:48The shell around the egg is quite
38:53strong.
38:54The babies must make a considerable
38:56effort to free themselves, and for
38:58some, it's more than they can manage.
39:00manage.
39:01So, she starts to crack the unhatched egg with
39:06her teeth.
39:07her teeth.
39:21Once the hard shell has been broken away, she has
39:23to pierce the leathery inner membrane.
39:26she gets the middle of the egg.
39:27when she loses her teeth.
39:28she gets the middle of the egg.
39:29she gets the middle of the egg.
39:30she gets the middle of the egg.
39:31Without her help, this baby might not have hatched at all.
40:01But the female caiman's maternal duties are not over even now.
40:10She will stand guard over her babies for the next few months.
40:16All crocodilians take good care of their young, but one of them takes parental responsibilities
40:22to a really astonishing level.
40:29The Janos of Venezuela, a lush wetland teeming with wildlife of all kinds.
40:43As well as birds, there are amphibious rodents, capybara, and a spectacle caiman.
40:57This female is looking after an extraordinarily large number of babies.
41:05But most of these are not in fact hers.
41:15This nursery pool is being used by several caiman families.
41:20But instead of all the mothers staying nearby, one of them has taken charge of the whole creche.
41:31Keeping an eye on all these energetic babies is not easy.
41:37There are lots of enemies around.
41:52When danger threatens, the babies all run for protection to the female, even though she
41:57may not be their mother.
41:59There are so many of them that there's not enough room for them all on her back.
42:14Soon, these babies will face another hazard, and one that's not quite so easy to escape from.
42:26The water that has kept them safe until now is beginning to dry up.
42:32Each year, in the space of a few short months, the Janos is transformed from a flooded paradise to a baking oven.
42:43For some babies, the unrelenting heat and the lack of water has already been too much.
42:59Any babies that are left alive will certainly die if they stay here.
43:08So the mother decides to leave.
43:11Oh.
43:12Oh.
43:13Oh.
43:14Oh.
43:15Oh.
43:16Oh.
43:17Oh.
43:18Oh.
43:19Oh.
43:20Oh.
43:22Oh.
43:23Oh.
43:24Oh.
43:25Oh.
43:26Oh.
43:27Oh.
43:28Oh.
43:29Oh.
43:30Oh.
43:31Oh.
43:32Oh.
43:33Oh.
43:34Oh.
43:35Oh.
43:36Oh.
43:37Oh.
43:38Oh.
43:39Oh.
43:40Oh.
43:41Oh.
43:42Oh.
43:43Oh.
43:44Oh.
43:45Oh.
43:46Oh.
43:47Oh.
43:48Oh.
43:49Oh.
43:50Oh.
43:51Oh.
43:52Oh.
43:53Oh.
43:54Oh.
43:55Oh.
43:56Oh.
43:57Oh.
43:59For the mother, this is certainly exhausting.
44:03For her babies, with their tiny legs, it must be a real marathon.
44:17Some start to fall behind.
44:21But she stops.
44:22The babies call constantly.
44:29She knows exactly where they all are
44:31and waits until every single one of them has caught up.
44:52Only when all are with her will she set off again.
45:01At last, safety.
45:25The babies are close to exhaustion.
45:38Without such devotion from the female,
45:54few, if any, of these baby caiman would have survived.
45:58And remarkably, most of them aren't even her own.
46:03When parental care was first described in crocodiles,
46:16the reports were dismissed as too extraordinary to be true.
46:25We may call reptiles cold-blooded, but they can show great tenderness.
46:33Reptiles and amphibians are full of surprises.
46:57They can look after their young with as much care as many a mammal.
47:03their displays can be as colourful as that of any bird.
47:17And they can astonish and enthrall us.
47:33Reptiles and amphibians are sometimes seen as simple, primitive creatures.
47:39That's a long way from the truth.
47:42The fact that they are solar-powered means that their bodies require only 10% of the energy
47:49that mammals of a similar size require.
47:52As a time when we ourselves are becoming increasingly concerned about the way in which we get our energy
48:00from the environment and the wasteful way in which we use it,
48:04maybe there are things that we can learn from life in cold blood.
48:09We filmed a lot of different reptiles and amphibians during the making of this series.
48:23We filmed a lot of different reptiles and amphibians during the making of this series.
48:37We were looking for extraordinary behaviour, preferably for things that had never been filmed before.
48:51To see such wonders, we needed the help of scientists who were working in the field.
49:06They're actually quite thin.
49:07They passed on to us their insights and their discoveries,
49:15and then they helped us to interpret the footage that we'd shot.
49:19I learnt a lot and had a lot of fun.
49:22But I was also alarmed to discover just how rare some of the subjects of our series have now become.
49:33One of our key locations was the Galapagos Islands.
49:36Here, giant tortoises were going to be among our stars.
49:39The scientists working for the Galapagos National Parks care for the wild animal populations,
49:46but they also look after one extraordinary, unique individual with whom I had a special appointment.
49:53This is the rarest living animal in all the world.
49:58There is none rarer.
50:01This is lonesome George.
50:03He's about the same age as I am, but his story starts a very long time ago.
50:11In the 17th century, when human beings first came to the Galapagos,
50:15there were about 15 different kinds of giant tortoises,
50:22each living on its own island or its own great volcano isolated by unpassable lava flows.
50:30There are 13 large islands in the Galapagos and many smaller ones,
50:37and they differ in both age and their vegetation.
50:41The tortoises differ too because their shells have evolved into the different shapes
50:45best suited for eating the food available on their own particular island.
50:50On islands where there's abundant food on the ground,
50:53the tortoises have dome-shaped shells and short necks that only need reach downwards.
51:00But on islands where the tortoises browse on higher bushes,
51:03their necks are longer and the shells are saddle-shaped at the front,
51:07so they can stretch their necks upwards.
51:11When the first ships arrived here, there were thousands of each kind of tortoise.
51:15But then people began to slaughter the tortoises for meat.
51:23They discovered the remarkable fact that these creatures could live
51:28for a year without water or food.
51:33So they took them on board their ships and slaughtered them at sea.
51:38The tortoises on Pinta Island were apparently exterminated.
51:42But then, in 1971, it was discovered that there was one lonely single survivor.
51:55That was lonesome George.
51:59This film was taken over 30 years ago by the team that brought George back to the Charles
52:04Darwin Research Station. The scientists hoped that another Pinta tortoise might be discovered
52:09in some corner of his island or even in a zoo somewhere in the world, but none has ever been found.
52:20So now George lives in his own enclosure, completely safe but entirely by himself.
52:26He's the last of his kind.
52:29It's better news for the other Galapagos tortoises.
52:32Felipe Cruz from the Research Station showed me some of the work being done there.
52:37They take eggs laid by wild tortoises and put them in incubators.
52:43The hatchlings are about the size of apples and have soft shells, so are vulnerable to predators,
52:48especially rats, that were accidentally introduced to the Galapagos.
52:56The young ones I saw were only a few months old.
52:58They're kept in special enclosures and given all the foods they need to enable them to develop hard, protective shells.
53:09It takes a few months for their shells to harden, and it's five years before they're totally predator-proof.
53:15So far, in total, we have repatriated over 3,000 tortoises.
53:273,000?
53:27Two different islands.
53:30Scientists are also helping to solve another man-made problem.
53:33Domestic goats that have run wild are eating the tortoises' food and destroying the precious
53:41plant cover that they need for shade.
53:44So, a systematic program of eradication has started.
53:47I was able to see the effects of this program for myself.
53:59We visited one island where, two years earlier, the goats had been eliminated,
54:03and the difference was dramatic.
54:05The lush vegetation had returned.
54:07Now, the tortoises can find the shade that is so important for them, and there's plenty of grass for them to eat.
54:24Reptiles are not alone in being under threat.
54:28The amphibians, if anything, are in even greater danger.
54:32Not since the disappearance of the dinosaurs has a whole group of the animal kingdom
54:36been under such threat.
54:39In Japan, one of the most dramatic of amphibians, the giant salamander,
54:44has fewer and fewer places to live.
54:52In Panama, we filmed the golden frog.
54:55Since we took this shot, the species has become so rare that the few survivors
54:59have been caught to be protected in zoos, so it's now extinct in the wild.
55:07The gharials that we filmed with their babies were nearly exterminated in the 1970s when they
55:12lost most of their natural habitat, and they're not safe yet.
55:18To try and halt their decline, their eggs are being collected, hatched in incubators,
55:23and the babies reared in captivity until they can be released in the wild.
55:27So there may be hope for them yet.
55:31The gopher tortoise we filmed in Florida is also in trouble.
55:35The areas where it digs its burrows have become prime real estate, and are now much sought after for
55:40building and farming.
55:44By explaining their problems to landowners and developers, they may yet have a future.
55:55In the great island of Madagascar, there are more species of chameleon than in all the rest of the
56:00world put together. But the destruction of the island's forests began centuries ago,
56:08and only a few patches are left. They too are still being felled, and chameleon species may be
56:13lost even before they've been identified.
56:21We will need to act now if we're not to lose what remains to us of the reptiles and amphibians
56:27that have survived for 200 million years.
56:32Lonesome George, it seems, is doomed to be the last of his kind. But at least he can be a living
56:40inspiration for us all to protect the remainder of the reptiles and amphibians of the world.
56:57The
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