BBC Life in Cold Blood E02 Land Invaders
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00:30Amphibians were the first backbone animals to leave the water and colonize the land.
00:53Today there are some 6,000 species of them and new ones are constantly being discovered.
00:59We may not often see them, but during the breeding season we certainly hear them.
01:15Choruses like this ensure that we are well aware of frogs and toads.
01:28And there are other kinds of amphibians that don't make themselves so obvious.
01:33Newts and their close relatives, the salamanders.
01:39And even ones that have completely lost their legs.
01:44But all amphibians have one thing in common, a moist skin.
01:49If that dries, they die.
01:52And dealing with that danger dominates their lives.
01:55How are they to survive away from water?
02:08Four hundred million years ago, the only backbone animals on the earth were fish.
02:13The land was empty except for insects and other invertebrates.
02:17But then one of those fish managed to haul itself out of the water and up onto the land.
02:24You can see what sort of creature that might have been if you go to northeast Australia.
02:29There the rivers only too often dry up.
02:35But one remarkable, ancient and extraordinary fish managed to survive because it has a rare
02:43talent for a fish.
02:46It has lungs and can breathe air.
02:49And there's one at my feet right here.
02:54Animals just like it date from precisely the time when the great invasion of the land
02:59took place.
03:00On occasion, it rises to the surface and gulps air.
03:06The air goes into a pouch that opens from its throat, where the oxygen from it is absorbed.
03:14This is a lungfish.
03:19It punts itself along the river bottom using two pairs of fleshy, muscular fins placed
03:25low on its body, just like simple legs.
03:32Sometime around 360 million years ago, one of its remote ancestors used such limb-like
03:39fins to push itself up onto the land.
03:48That pioneer may have looked much like this strange monster that haunts the waterways
03:55of Japan.
03:59It's the giant salamander, the biggest of all living amphibians, that grows to a metre
04:05or more in length.
04:12It too has lungs and breathes air, but even so, it almost never leaves the water.
04:22Males make their dens in both natural and man-made retreats in the riverbanks and defend
04:27them against all other males.
04:31A newcomer arrives, looking for a breeding den of his own.
05:01It won't be here.
05:20The resident male has good reason to be so defensive.
05:26He's guarding a batch of eggs left by a female who visited him a few days earlier.
05:33Like fish eggs, amphibian eggs have no protective shell.
05:37They can only develop in moisture of some kind, and amphibians, no matter where they
05:41live, must find ways to provide that.
05:48The alpine newt lives on land for about half the year, hunting for slugs and worms.
05:55In winter, they lie dormant beneath the snow, but come the spring, they get the urge to
06:00breed.
06:06A female is swollen with eggs and needs to lay, so she has to go back to water.
06:20And there, a male is awaiting her.
06:25He has already developed his breeding colours and knows how to flaunt them to impress her.
06:35He wafts a pheromone, a sexual stimulant, towards her with beats of his tail.
06:54She senses it through her nostrils.
07:07She tastes it in her mouth.
07:15Having caught her interest, he turns and moves away from her.
07:22His genital opening is greatly swollen, and from it comes a small white capsule.
07:28It's a packet of sperm.
07:34The female, led by the male, walks directly over it.
07:40He stops, and so does she, with her genital opening exactly above the sperm packet.
07:47And she picks it up.
07:55So as in many fish, mating occurs with little or no physical contact between the two partners.
08:04Two or three days later, she begins to lay.
08:13Each of her eggs is deposited individually.
08:29As an egg emerges, she wraps the leaf around it with her hind legs and then holds it there
08:35while the edges bond.
08:38She will lay several eggs a day, for week after week, until eventually she may have
08:43produced several hundred.
08:51But all this has to be done in water.
08:54She has still not broken her link with her fishy ancestry.
09:01In North America, in the eastern half of the country, there are many kinds of small salamanders,
09:07only a few inches long, that have taken one further step away from the aquatic life.
09:15In spring, the woodlands are drenched in rain, and suddenly, in response, an amphibian army
09:22appears among the leaf litter.
09:27Marbled salamanders.
09:33To emerge are the males.
09:35They're in search of females.
09:39They have spent the winter deep in the damp leaf litter, breathing by absorbing oxygen
09:44from the air through their moist skins.
09:46For them, the land is truly home.
09:49If they were submerged in water for any length of time, they might well drown.
09:56Nonetheless, their courtship techniques are much the same as those used in water by newts.
10:07The males produce pheromones that excite the females.
10:19They deposit capsules of sperm on the damp ground.
10:24And the females crawl over them and take them in.
10:29In due course, each female lays her soft-skinned eggs on the ground and stays beside them on guard.
10:38Here, it's damp enough to prevent her eggs from drying, and they're already developing rapidly.
10:51Eventually, the continuing rains flood the woodland floor.
10:58But now, the females' needs and those of her eggs are exactly opposite.
11:03They will need water in order to breathe, but she could drown in it, so she has to leave.
11:15The young inside their capsules are developing into creatures fundamentally different from
11:20their parents, a form that is characteristic of amphibians.
11:24They are becoming tadpoles.
11:28They swim free, equipped with feathery gills that enable them to extract oxygen from the water.
11:34They are truly aquatic creatures.
11:39But they have front legs as well as gills.
11:49And within days, they develop back legs as well.
11:57As time passes, they grow stronger.
12:00Their gills wither and disappear, and at last, they are miniature versions of their parents
12:05and are ready to leave the water forever and to start on their land-living lives.
12:12But what tempted those ancient fish to leave the water in the first place?
12:19Food.
12:21When the first amphibians moved out of water, the land was already swarming with insects.
12:27And the amphibians have evolved a special weapon with which to catch them.
12:40Salamanders, however, have not yet developed the athleticism needed for a high-speed chase
12:47on a lightning pounce.
12:49Their hunts are rather solemn, sedate affairs.
13:14A simple contraction of the muscles surrounding the tongue is all that's needed to shoot it forward.
13:25Some salamanders have a tongue that is about three-quarters the length of the body,
13:30but most species have to get pretty close to their prey if they are to catch it.
13:42Although the adult marble salamander lives entirely on land,
13:46it nonetheless needed water at the very beginning of its life.
13:50But there are other species of salamander in North America
13:53that have managed to break even that link with their distant aquatic past.
14:05This is a gold mine.
14:07The people who dug it found nothing.
14:10Biologists, who came later, found gold of their own special kind.
14:24They discovered a colony of a species called the slimy salamander
14:28that could be properly observed throughout the summer
14:31when normally they're hidden in the leaf litter.
14:34They were all females, and their behaviour proved to be very surprising indeed.
14:45These salamanders come down in early summer, in about June,
14:51and will travel several hundred metres down along this mine shaft
14:56to exactly the same ledge, within an inch or so, that they used the previous year.
15:03And they have been seen doing that for at least five or six years.
15:08And they don't eat.
15:10They will stay down here for six or seven months,
15:14sustained only by the food reserves that they've accumulated in their fat tails.
15:23Down here, there is permanent moisture, however hot and dry it gets outside.
15:28The salamanders clearly prefer to cluster together, close to one another,
15:33for the rock walls of the mine shaft elsewhere are totally uninhabited.
15:39However, this open-plan way of life, while it's clearly very successful,
15:45numbness comes at a price.
15:49Some of the females here are up to no good.
15:53They failed to fatten up enough during the spring,
15:56and they're hungry and in search of a good meal.
16:00And the eggs and young of their other salamanders will do very well.
16:09To see exactly what these creatures are doing,
16:12we need to turn off our torches and turn on the infrared camera.
16:17Here comes one of those marauding females.
16:33She must have located this mother guarding her eggs by smell,
16:37for all this is going on behind closed doors.
16:41She must have located this mother guarding her eggs by smell,
16:45for all this is going on in total darkness.
16:49So, some amphibians, when needs be, are neither sluggish, insensitive,
16:55nor lacking in maternal concern.
17:01The salamanders, however, are not afraid of the dark.
17:05They're not afraid of the light.
17:09They're not afraid of the dark.
17:13They're not afraid of the dark.
17:18And mother wins the day.
17:24The salamanders' need to keep moist
17:27means that they seldom come out into the open,
17:30but find their prey by pushing through the leaf litter.
17:34And to do that, it helps to be slim.
17:38Very slim.
17:40Legs are less in the way if they're small.
17:44And one great group of burrowing amphibians
17:47has lost its legs altogether.
17:56You might think that this was a giant earthworm,
18:00but if you picked it up, you would immediately realise
18:03it's got a strong, firm backbone.
18:06It's a caecilian.
18:09Caecilians are found in all the world's oceans.
18:13Caecilians are found in almost all rainforests.
18:16But they are seldom seen,
18:18for they spend nearly all their lives underground.
18:23The female, having produced her young,
18:26stays in her nest chamber to protect them.
18:35Caecilian eyes are rudimentary.
18:37They're covered in skin and scarcely function.
18:40In the darkness underground, however,
18:42the animals have no need for them.
18:47The young enthusiastically lick a secretion
18:50from a gland at the end of their mother's tail,
18:53and their constant hunger seems to be the factor
18:56that keeps this little blind family together.
19:08In a single week, the young incredibly increase
19:11their weight by ten times,
19:13apparently just from drinking her secretion.
19:16But could that be their only food?
19:20As we filmed, one of the youngsters
19:23revealed a clue to their rapid growth.
19:25It yawned.
19:29It already had hooked teeth like a baby shark.
19:33It surely doesn't need these
19:35if it's going to do nothing but drinking.
19:37Could it be feeding on something else?
19:41A few hours later,
19:44our cameras, for the first time, revealed the answer.
19:49There was a sudden frenzy of activity.
19:52The babies started swarming all over their mother.
19:56MUSIC
20:10They were tearing at her flanks,
20:12ripping off segments of her skin,
20:14skin that proved to be full of fat.
20:26It turned out that she re-grew her skin every three days
20:30to provide her young with another nourishing meal.
20:45Blind, elongated and legless caecilians may be,
20:49but simple, inoffensive earthworms they are not.
20:53The most numerous and successful of all amphibians, however,
20:58have kept their legs and developed them spectacularly.
21:04MUSIC
21:23Some are walkers.
21:34Others are climbers.
21:46There are hoppers.
21:49There are even gliders
21:51who use the membranes on their feet like parachutes.
21:55If their skin is very moist,
21:58we call these creatures frogs.
22:01If it's less so, we call them frogs.
22:06They are also known to be very sensitive to water.
22:11They are also known to be very sensitive to water.
22:16They are also known to be very sensitive to water.
22:20If their skin is very moist, we call these creatures frogs.
22:24If it's less so, we call them toads.
22:27But they all belong to the same group.
22:38There are some 5,500 different kinds of frogs and toads
22:44in the world today.
22:46And here, in the leaf litter in this Madagascan forest,
22:50is the tiniest of them all.
22:53This is fully adult.
22:56And in its tiny body, which is only a centimetre long,
23:01is packed a beating heart, a skeleton, a gut, a brain.
23:07It's a miracle of miniaturisation.
23:12And this basic body plan not only comes in all sizes,
23:17but many different shapes,
23:19which has enabled frogs and toads
23:22to colonise all kinds of different environments.
23:28Out of water, frogs found a new way to communicate with one another.
23:42AMPHIBIAN LUNGS
23:47Amphibian lungs are comparatively feeble,
23:50so frogs amplify their calls with cheek or throat pouches,
23:54which act as resonators.
23:59The call of a frog in this South African pool
24:02can be heard over a mile away.
24:07It's the painted reed frog,
24:10the loudest caller of all for his size.
24:26But a female is not only impressed by the loudness of a male's call.
24:34She also judges him by how frequently he manages to make that call.
24:40CLICKING
24:50Calling is a very demanding activity,
24:53requiring a male to increase his energy consumption by about 20 times.
24:58So in picking the loudest and fastest caller,
25:01the female is also selecting the fittest and most vigorous male
25:05as the father of her offspring.
25:10CLICKING
25:17He's the one.
25:25Success.
25:27And silence for a few minutes.
25:31BIRDS CHIRP
25:37In some circumstances, however, calls need reinforcing with gestures.
25:46The sound of rushing water could drown out the calls of a frog.
25:52However, here in this stream in Panama,
25:55there's a species living alongside
25:58that has developed a novel way of dealing with that problem.
26:04The rare and wonderful golden frog.
26:07It does have a voice, but it's not loud.
26:18Individual males set up their territories beside the river
26:22and then wait for females to turn up.
26:25And since good positions for the territory are not common,
26:29they may have to hold them against intruders.
26:34And here one comes.
26:38Just in case his call is inaudible, he makes his message clear with a wave.
26:49And his rival waves back.
26:52He repeats his message so there's no misunderstanding.
27:08But rival is not deterred.
27:12Well, that makes things perfectly clear.
27:15BIRDS CHIRP
27:19Another arrives. Perhaps at last this is a female.
27:38No, it's another male, so there will have to be a wrestling match.
27:45BIRDS CHIRP
27:48That should teach him.
27:51And his rival signals submission by keeping his head down.
28:01WHISTLE
28:15BIRDS CHIRP
28:23Now, where are those females?
28:29And here she is.
28:32She is pure, unblemished gold and much bigger than he is.
28:45While he is fully occupied, another challenger arrives.
28:54Since he's already in position,
28:56there's no point in breaking away for another wrestling match,
29:00so he hangs on.
29:07The golden frog has a powerful poison in its skin,
29:11so it can afford to be conspicuous.
29:14But most frogs find safety in camouflage.
29:22This is a South American red-eyed tree frog,
29:26a close match for the leaves on which it habitually sits.
29:33The eggs are not very conspicuous either,
29:36just little blobs in transparent jelly.
29:40And they're always laid over water.
29:44MUSIC
29:47They develop very rapidly.
29:49MUSIC
30:10In less than a week, they become recognisable tadpoles,
30:14almost ready for freedom.
30:16Then the jelly liquefies
30:18and they simply drop into the water beneath.
30:23But some don't survive long enough to do so.
30:31Wasps raid the cluster
30:33and carry off the unhatched tadpoles to feed their young.
30:46MUSIC
31:08But the tadpoles are not entirely helpless.
31:11By the time they're five days old,
31:14they know when they're under attack
31:16and, what's more, they can do something about it.
31:22There.
31:24Quick wriggle and the tadpole drops to safety.
31:36The alarm spreads quickly through the whole cluster
31:39and they all take a dive.
31:53Their tails are not yet fully developed,
31:55but they can swim well enough
31:57to take refuge beneath the leaves of the water plants.
32:00MUSIC
32:22So, if there's a choice between being carried off by a wasp
32:26and taking an early bath,
32:28there's no competition.
32:32But not all frogs abandon their young.
32:35If you're big enough, you can stay and defend them
32:38and the male giant African bullfrog is as big as a football.
32:44His pool, which formed during the rainy season,
32:47lies near the margin of a much bigger pond.
32:53The nursery pool was a good place to live
32:57The nursery pool was a good place to lay
32:59for it had none of the predators
33:01that abound in the bigger permanent pond.
33:05But as the dry season warms up,
33:08that smaller pool begins to evaporate.
33:13Tadpoles are now in real danger.
33:17Father takes action.
33:22He starts to dig a canal
33:25to enable his endangered tadpoles
33:27to reach the deeper pond nearby.
33:38It will be touch and go.
33:40But if they can only get to the bigger pond,
33:42they're now vigorous enough to have a reasonable chance of survival.
33:52Breakthrough.
33:55Breakthrough.
34:02And father leads the way.
34:18In the rainforests of South America,
34:21the daily rains create a multitude of tiny pools
34:24in the centre of many plants.
34:28This tiny poison arrow frog
34:31is carrying his tadpole picker back.
34:33It hatched on a leaf
34:35and now he's taking it to a pool in a bromeliad
34:38high up in the branches.
34:40The tadpole wiggles off.
34:44He may have half a dozen babies,
34:46each of which he puts into its own tiny pool.
34:54He makes regular tours of all his nurseries
34:57checking on his tadpole's welfare.
35:09This youngster is hungry
35:11and tells him so by nibbling his legs
35:14and vibrating against his body.
35:17But the male can't feed the tadpole himself.
35:20He needs help.
35:32He has to find a female.
35:35There she is.
35:42He calls.
35:54He calls again.
36:01He calls again.
36:05And she follows.
36:14He has to lead
36:16for only he knows exactly where he deposited each tadpole.
36:22This one is now very hungry indeed.
36:30He calls to the female encouragingly.
36:35She jumps in
36:37perhaps to assess the situation.
36:44Out she comes
36:46without having done what's required
36:48so he keeps calling.
36:51In she goes a second time.
36:53This time she produces food for the hungry tadpole
36:57an infertile egg.
36:59There.
37:06Out she comes
37:08and mother and father embrace.
37:11Baby has its dinner.
37:14Australia is home to many of the most beautiful places in the world.
37:20It's a place where you can be yourself
37:24and you can be happy.
37:26You can be in the moment
37:29and you can be in the moment.
37:32You can be in the moment
37:34and you can be in the moment.
37:37You can be in the moment
37:39and you can be in the moment.
37:41Australia in the southeast
37:44has temperate rainforests.
37:48A cluster of frogs' eggs on the damp ground.
37:52When these hatch, the tadpoles will also need a moist nursery.
37:57Father, a marsupial frog, is on guard.
38:01The eggs are developing fast.
38:04The male has to keep a careful eye on them
38:07for he must be close beside them at the very moment when they hatch.
38:20It's going to be a long wait.
38:23At least 11 days.
38:25He seems to have decided that the crucial moment has arrived
38:29and lowers himself onto the eggs.
38:37As he does so, the tough egg membrane
38:40begins to break apart.
38:43The tadpoles have to be careful
38:46because the eggs can break apart.
38:49As he does so, the tough egg membranes liquefy
38:53and the young wriggle free.
38:56He has two pouches in his skin, one on each hip,
39:00and the tadpoles start to squirm into them.
39:13Competition between the tadpoles is intense
39:16for there are more of them than he can accommodate in his pouches.
39:47At last, he's taken on board as many as he can manage.
39:53He will now look after them for up to six weeks.
40:01The young remain in his pouches, continuing their development,
40:05fuelled by the remains of the yolk in their infant stomachs.
40:10And then, one night, his behaviour changes.
40:16His flanks are rippling.
40:28The first of his young is emerging.
40:40He is now in his pouches.
40:45He is now in his pouches.
40:50He is now in his pouches.
40:54He is now in his pouches.
40:58He is now in his pouches.
41:02He is now in his pouches.
41:05He is now in his pouches.
41:10The profound transformation that converted a tadpole into this young frog
41:15took place entirely within its father's moist pouch.
41:29The parched bush country of southern Africa.
41:32Here, it rains only twice a year, and then only briefly.
41:40But when it does, the ground in places erupts.
41:53Rain frogs, as they're aptly called,
41:56have been waiting for months below ground for this moment.
42:02After starving for so long, they're keen to feed.
42:33As darkness falls, the males begin to call.
42:52Females are fat with eggs.
42:56The males are so much smaller that they can't embrace a female,
43:01so they produce glue from glands on their underside
43:05and stick themselves to their partner's back.
43:10But sometimes, that only results in a change in behaviour.
43:16The males are so much smaller that they can't embrace a female,
43:20so they produce glue from glands on their underside
43:24and that only results in a chain of enthusiastic but undiscriminating males
43:29stuck to one another.
43:38Their brief time above ground has come to an end.
43:41The female starts to dig.
43:45The diminutive male being stuck on goes with her.
43:49He will fertilise the eggs later below ground.
43:55Her stay on the surface is over.
44:03The female has excavated a little chamber for herself
44:07and below that, she's made a second one,
44:10which she's filled with a frothy foam.
44:16This is the nursery for her tadpoles.
44:25Tadpoles.
44:44The female stays underground, away from the lethal heat,
44:48for several more weeks.
44:55By now, her offspring have almost completed their time as tadpoles.
45:11The rains return.
45:24Below ground, the youngsters await their release.
45:47The female leads the way.
45:51And her brood are with her.
45:55MUSIC
45:59MUSIC
46:22Rain is even rarer in Australia.
46:25There, in the central deserts, it may not fall for years on end.
46:32But there are amphibians even here.
46:35Little toads that remain underground
46:38in a state of suspended animation for years,
46:41just to take advantage of a few rainy days.
46:47After the rains have fallen, spadefoot toads all emerge together.
46:52They must feed and breed, if possible, before the sun rises.
47:04But the desert dries only too quickly, even after the heaviest of storms.
47:09Temperatures rise to 50 degrees centigrade.
47:13Now, water will evaporate instantly.
47:16This is one of the hottest places on Earth.
47:20So the toads have to retreat, once again, below ground.
47:25The miracle is that they're here at all.
47:31A toad that can live in as parts of the desert as this
47:36is impressive evidence of the versatility of the amphibians,
47:40the way they can adapt their behaviour and their anatomy
47:44to live so far away from water.
47:46But there's one group of animals that can really call the desert their own.
47:51The lizards.
47:53And we'll look at them in the next episode of Life in Cold Blood.
48:07Amphibians are the most threatened group of vertebrates on the planet.
48:12In recent years, a strange and lethal fungal disease
48:16has started to spread among them.
48:20The golden frog, which lives only in one small area in Panama,
48:24was in particular danger as the disease is already on the frontier of its territory.
48:29If we were to film it at all, we would have to move quickly.
48:36For series producer Miles Barton, that meant cutting short Christmas.
48:42MUSIC
48:54We had been told that in Panama, the frog's few remaining breeding streams
48:59were being rapidly destroyed by the building of a new road,
49:03making the last tiny population even more at risk from the disease.
49:09The fungus clogs the animal's moist skin.
49:13Since all frogs breathe through their skin, infected animals die from suffocation.
49:21Frog biologist Eric Lindquist,
49:23who first described the golden frog's signalling behaviour,
49:27helped the film team to thoroughly disinfect their kit
49:30before travelling into the frog's territory.
49:34Freshly scrubbed up, Eric took the team
49:37to one of the golden frog's last known breeding sites.
49:46But would they still be there?
49:50Yeah, you hear that? That's a male calling.
49:57OK, we have another male crawling up over here.
50:03Crawling up the rock face.
50:06But with the fungus approaching at a rate of up to 25 miles a year,
50:10the frogs were rapidly disappearing from all their known breeding sites.
50:14The advance crew immediately set about
50:17filming as much of the behaviour as they could.
50:28By the time I arrived, there was only one remaining location
50:32where the frogs survived.
50:40Where exactly are we going?
50:43I would prefer not saying precisely.
50:46You see, this is really the last population
50:49of the golden frog left in the wild.
50:51And historically, the locals have been collecting out these animals
50:56as good luck talismans,
50:59and so now, left with just one population,
51:02I'm concerned that if this secret locality gets given out,
51:07there will be international collectors that would come.
51:11Really?
51:13Sure. They're rare enough now
51:16where many people would pay top dollar for these animals.
51:20Were they ever what you might call common?
51:23When I talk to people who have been here in the past,
51:26they say that the populations were so abundant
51:29that one would have to watch where they're stepping to keep from killing one.
51:33Really? Yes.
51:36Eric has his own low-tech method of finding them,
51:40which he assures me normally works.
51:51See, when you call, sometimes they'll call back
51:54and they'll reveal their location.
51:56Sometimes they're tucked away behind leaves
51:58and they're really difficult to find.
52:00Hopefully we can elicit a response.
52:08It's the fastest way to get them to shut up.
52:15Was that him? Yeah, that's him.
52:20So they're here.
52:22They're here.
52:24There's one over here.
52:30See him right there? Yeah, yeah, yeah.
52:32Looks like a male.
52:34I can do it again.
52:45You have to hum and whistle at the same time.
52:47Come on, do it.
52:53WHISTLING
53:00Now we knew the frogs were still here, we could complete the filming.
53:07The local people have always treasured their remarkable little frog,
53:11but Eric was the first to document its signalling behaviour.
53:15It was an animal that was just walking.
53:17I wasn't sure if the animal was trying to flush out prey
53:20or if it was using it in a communication role.
53:24And so a group of us set out to look at whether or not this was communication.
53:29We tried mirror presentations to the animals
53:32and when you presented them with a mirror, they would hand wave at the mirror,
53:36as opposed to, say, maybe the backside of a mirror that didn't have a reflective surface.
53:41Some of us have looked specifically at an LCD screen,
53:45a little television, with a hand-waving, semaphore-ing frog
53:50and it has elicited a number of responses, specifically from males.
53:55Well, you show a television picture to a male and he waves back.
53:58He waves back and he'll even call to the male on the television screen.
54:03It's really fascinating. Yeah, absolutely.
54:07They then experimented with a life-size plastic model complete with waving arm,
54:12the sort of high-tech gear I thought I might manage to operate myself.
54:32It's not as easy as you might think.
54:36Eric showed me how it should be done.
54:39You've got to get that slow-motion wave just right.
54:47The frogs waved.
54:58They called.
55:01They called.
55:06They even attacked.
55:09So that wave really is a form of communication.
55:13So they're just saying, keep off, keep off. Huh? Is that right?
55:17We're not sure. Sometimes there seem to be certain hand waves that may indicate appeasement,
55:23showing that I'm just walking through, perhaps, your territory, don't bother me.
55:28Really? Ah, please.
55:32But how endangered is the golden frog?
55:36This is it. What you see, you're going to be the last crew to film these in the wild.
55:45And indeed, we were.
55:47Soon after finishing filming, the local scientists decided the time had come
55:52to take all the surviving golden frogs into captivity.
55:56Before the fungus arrives here and kills them all.
56:00They, and other rare species of frog, also threatened,
56:03were being brought back to a special frog hospital,
56:06where I was introduced to some of the other patients.
56:09So, what are these? They're nocturnal, so they...
56:12Here, they're being treated daily with a fungicide.
56:15But without a vaccine to protect them, and with the fungus still at large in the forest,
56:20they can't be reintroduced into their proper home.
56:27Frogs, so common in these humid forests, are crucial links in the ecology.
56:32If they disappear, all kinds of food chains will be broken,
56:36and the effect could be little short of catastrophic to wildlife in general.
56:42And sadly, for now at least,
56:44it seems that the golden frog has waved its last in the wild.