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Otters are playful, adaptable and champion swimmers,
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00:00.
00:09Rarely seen, they have a near-mythical reputation.
00:14They have boundless energy and are able to dive deep
00:22and catch the fastest of prey.
00:27Otters.
00:31My name is Charlie Hamilton James,
00:35wildlife cameraman and otter fanatic.
00:40I've been observing and filming these shy but relentless animals
00:45for the last 25 years.
00:48For me, otters are the ultimate predator,
00:51perfectly bridging the gap between two worlds, one dry, one wet.
01:01Yet across the planet, their populations have hung in the balance.
01:06I've done what I can for their conservation.
01:09However, many remain in danger.
01:13But otters are fighters.
01:16Supercharged with a huge amount of spirit and determination.
01:22And now, with the help of three orphaned cubs,
01:27some groundbreaking experiments.
01:30It's done it.
01:31It's done it.
01:32That was it.
01:33And some incredible wild encounters.
01:38I'm going to reveal their survival secrets and just why I think otters are such a special group of animals.
01:59I've spent my life searching for glimpses of these rare and elusive creatures.
02:05They're nervous and fearful of humans.
02:10But there's one place where they're bolder than most.
02:14Florida.
02:20Here, clear spring-fed rivers provide the ideal opportunity to film otters moving and hunting underwater.
02:31Something few have ever done.
02:35If I succeed, it'll be the perfect way to begin a journey into their seldom seen world.
03:08They know I'm here.
03:10They're far too inquisitive not to have noticed.
03:13But they don't seem to mind.
03:23There are more otters here than anywhere I've ever been.
03:30But typically, they don't keep still for long.
03:41North American river otters can cover over 40 kilometres a day.
03:46And swim for 400 metres without coming up for air.
03:53If you're going to observe otters in the wild, you need patience and a bit of love.
04:02I spot a telltale sign.
04:05A trail of bubbles.
04:17Absorbed by foraging, this is my chance to get close.
04:25I want to see how it's hunting.
04:29Something I've never achieved before.
04:34But I know, with just a flick of its tail, he could be off in a flash.
04:41He's so focused.
04:44I just need to hold my nerve.
04:57In 25 years of watching otters, I've just got these little glimpses occasionally of them underwater.
05:02And here, in a single morning, I've seen more otters underwater than in that whole 25 years.
05:14But what's been really interesting is actually looking at how they're hunting.
05:22It made me watch him and understand and look at the way he was doing stuff.
05:26Look at the way he was swimming and fishing in a completely different way.
05:33In this one incredible experience, a completely wild otter allowed me to come here, hang out and watch him fish
05:41underwater.
05:53There's an otter right now.
05:58This place is so amazing.
06:01There's just otters everywhere.
06:03It is otter heaven.
06:04I need to go get back in the water with him.
06:07It's all very well sitting here talking to a camera.
06:10But I'd rather be swimming with an otter.
06:14The experience has reminded me why otters have captivated me for so long.
06:21They are incredible predators.
06:26Energetic, inquisitive and versatile.
06:31Traits they share with their extended family.
06:34The musterlids.
06:36An ancient and diverse group of carnivores that includes weasels, stoats, badgers and martins.
06:45Otters can be found on nearly every continent.
06:48From the Arctic Circle to the swamps of Africa.
06:53And from desert oases to the tempestuous seas of Patagonia.
07:03But there are some things that unite all otter species.
07:08They have long, highly flexible bodies.
07:14A powerful tail and webbed feet.
07:21Some can dive to a hundred meters.
07:26And hold their breath for over four minutes.
07:36But despite their amazing physical abilities.
07:40All over the world, otter numbers have been in decline.
07:48They've been hunted for sport.
07:52And for their fur.
08:01They've lost their food to human greed.
08:06And have seen their habitat poisoned and ruined.
08:13But given the chance, otters are survivors.
08:19Enduring against all odds.
08:22It's one of the reasons I've always done what I can.
08:27Caring for otters in need.
08:30I've even welcomed them into my family.
08:40Honey, a Eurasian otter too dependent on humans to be released.
08:45Held a special place in my heart.
08:50And the time I spent with her only made my love for otters stronger.
09:01To help me reveal what I believe sets otters apart.
09:05I'm going to follow three male orphan river otters.
09:09On their own story of survival.
09:12As they grow.
09:14They'll be taught the vital skills they'll need.
09:17For a life back in the wild.
09:21After being abandoned by their mothers.
09:23The orphans were brought to Wild Instincts Wildlife Rehab Centre.
09:28On arrival, they were weak.
09:31Defenseless.
09:32And would not have survived the night.
09:36Attempting to mirror their wild diet.
09:39Centre manager Mark is giving them chopped fish.
09:42And milk formula.
09:47But he has concerns about the weakest orphan.
09:52He came to us with kind of a bad leg.
09:54He injured the joint on his right rear leg.
09:56So we're not quite sure whether it's going to heal enough for him to be released or not.
10:00And he also did a slight injury to the joint right in here on this leg also.
10:05And even the good leg is not necessarily a good leg.
10:08So what we're going to do is try to find a zoo for him.
10:11If he's not able to be released back into the wild.
10:13And if we're unable to find a zoo, then he may have to be euthanized if we can't find a
10:18place for him to go.
10:21To keep any attachment to a minimum, it's Mark's policy not to name any of the animals in his care.
10:31Now eight weeks old, the cubs need to tackle an essential survival skill.
10:38Learning to swim.
10:46Curiously, baby otters don't really like water.
10:58So Mark needs to teach them their most important life lesson.
11:03that water isn't something to be afraid of.
11:11Just like their mother would in the wild, Mark makes soothing calls to reassure them.
11:20Each time they try to get out, Mark plops them back in.
11:27But their swimming lessons don't last too long.
11:34That's because of another surprising quirk of otter biology.
11:39Their coat doesn't become waterproof until they're 12 weeks old.
11:44Until then, being wet could lead to hypothermia.
11:50So surrogate mom, Mark, does what he can to help out.
11:55Normally in the wild, what they would be doing is rolling around in the grass and the dirt
11:59to kind of get some of the water off themselves.
12:01And so we can use the towels to kind of help us out a little bit.
12:14Wild otter cubs face exactly the same issue.
12:17So the adults only take them for short dips to stop them getting cold and waterlogged.
12:37It's exactly what I saw with a family of giant river otters in the Amazon.
12:50Wow, look at that. Tiny.
12:55That is really young. That can't be more than six weeks old.
13:01He's got another one.
13:08Giant river otters are highly social.
13:11And with such young pups in the water, the whole family helps out.
13:21But they're too small to start swimming properly.
13:25It's just a taster session under the watchful eyes of their parents and siblings.
13:31Eventually, they'll become accomplished enough in the water to catch fast wild prey.
13:46Back in Wisconsin, otter foster parent Mark is about to start teaching the orphans how to fish.
13:54But first, the orphan with the bad leg needs a little extra help.
14:01So Mark has designed a swimming aid and is giving him a course of aquatherapy.
14:11So it looks like the little apparatus we put on there seems to be accomplishing what we wanted it to
14:15do.
14:15It keeps him afloat and he's using his rear legs much better than he was before without it.
14:20So hopefully this will be some good therapy and get him on the path to being what it needs to
14:25be.
14:30He's obviously a little fighter.
14:33As I arrive, Mark's just about to give them live fish for the first time.
14:55Mark adds some minnows to the paddling pool and hopes that hunting is more instinctive than swimming.
15:05Go on then.
15:10Yesterday we were doing a little bit of diving and swimming around and now there will be something to swim
15:14and dive around for.
15:15So we'll see if they have any luck chasing him around.
15:20This one's completely at home, let's just chase the fish.
15:23Exactly, exactly.
15:24Straight away.
15:25And that's just in a few days, it's gone from nothing to chasing fish underwater.
15:29Right.
15:30He's got a fish.
15:31Did he?
15:32He's got one.
15:33Oh no, he's got it go.
15:34He's got it.
15:35He's got it.
15:35Yeah.
15:36That's his first fish.
15:37Look at that.
15:38That's his first fish.
15:38Isn't that amazing?
15:40Yesterday he wasn't even putting his head underwater and today he's got his first little fish.
15:45He's playing with it.
15:45That is amazing, isn't it?
15:46Look, he's just rolling around playing with it.
15:48That's a great moment for them.
15:49Wow.
15:52Fishing for the orphans appears to be innate.
15:55It's a good sign, but it's something they'll need to hone.
16:01Do you know what?
16:04To me, there is nothing in the world that compares to otters.
16:09I could sit here all day every day and do nothing else the rest of my life.
16:13Just hang with otters.
16:16That's when I'm at my happiest.
16:19As the orphans get bigger, their swimming abilities will develop too.
16:25Until they're as agile in the water as the fish they hunt.
16:35But otters aren't just masters of the water.
16:38They spend up to 80% of their lives on land.
16:44Their ability to lead this semi-aquatic double life is what allows them to cope with diverse habitats and prey.
16:54The key to this lies in their physiology.
16:58And back in the UK, I've got a furry friend to help reveal the secrets of their success.
17:06This is Rudy.
17:08He's an Asian small clawed otter.
17:12Or short clawed otter, because he's got tiny little claws.
17:16And the aim is to get a really decent look at Rudy and how his body works, how his physiology
17:22works.
17:23How he turns from an animal that can run around on the land to an animal that's as fast as
17:28a fish in water.
17:29And it gives me an excuse to just hang out with an otter.
17:35I think you need to go and see the dentist, Rudy.
17:39So this camera is going to do some nice slow motion shots.
17:44And I can track along with the otter.
17:48And then we can get a good look at how it's running.
17:52And Rod here is going to film Rudy's swimming in close-up and particularly in slow motion.
17:58The thing I've always wondered watching them and filming them is how do they go from land to water and
18:03be so brilliant at both.
18:05And I think the reason I like what we're doing now is because we're going to get a really detailed
18:09look at that.
18:10And try and get some understanding of how they manage to do that.
18:14Because very few animals can just flip between two worlds like that.
18:19Otters do it brilliantly.
18:23When we slow the action right down,
18:28we can see exactly what's going on.
18:34Otter spines are highly flexible,
18:38allowing Rudy to rotate his hips,
18:42swing his leg forward,
18:45and plant his feet securely on the floor.
18:50And use his powerful tail for balance.
18:57And unlike most land-based carnivores,
19:00his front feet are well developed,
19:03with long, dexterous fingers for foraging and handling prey.
19:13By bending their highly flexible spines,
19:17otters are able to decrease the distance between shoulder and hip by over 20%,
19:22allowing them to bound,
19:25running up to 18 miles an hour.
19:29But the adaptations that allow them to live a semi-aquatic life become clear as Rudy enters the water.
19:37A substance 800 times denser than air.
19:42As he puts his head into the water, his vision becomes blurry, just like it does for us.
19:50But an almost magical adaptation allows him to correct this, like an inbuilt pair of swimming goggles.
19:59At first, the density of the water stops light rays being brought into sharp focus on his retina.
20:07But Rudy has highly specialized muscles in his iris that squeeze the lens so that its face bulges forward.
20:16This refocuses the light rays onto the back of his eye, giving him sharp, underwater vision.
20:25Now that he can see clearly, he enters the water fully and his next trick is revealed.
20:32Pushing his broad head forward and rotating his hips, he's able to straighten his body like a torpedo.
20:39Tucking his legs in, he reduces the water's drag.
20:47Only untucking them when he wants a burst of speed.
20:53Next, he uses his flexible spine in combination with his tail and webbed rear feet to turn and twist in
21:01the water.
21:04The agility of otters blows me away.
21:15Rudy has mastered the skills for a semi-aquatic life.
21:19But our orphans in Wisconsin are just learning how to make the most of their two worlds.
21:26They're now 12 weeks of age, old enough to move outside into an enclosure with permanent water.
21:36Where Mark is going to introduce them to some different prey.
21:41So today we're going to do some freshwater clams, we're going to do some crayfish, then we're also going to
21:45do some frogs.
21:47We're going to start out by introducing the clams first.
21:50And since they really don't know what these things are, what I'm going to do is actually have to cut
21:53them open for them.
21:54So I'm going to give each one a clam, then what we'll do is we'll throw some in the pond,
21:57let them kind of figure it out because they'll get the taste for it and realize that, hey, this is
22:01something I can eat.
22:04A wild otter's diet is broad.
22:07They catch and eat everything from snails to octopus.
22:12And their inquisitive nature has led to one species evolving an incredible talent.
22:18The use of tools.
22:25Sea otters feed on crustaceans and mollusks.
22:29But their hard exoskeleton makes it notoriously tricky to get into.
22:39So each otter has preferred tools for accessing its favourite foods.
22:47Be it a rock for opening clams.
22:52The bow of an expensive boat for oysters.
23:02Or an empty beer bottle for barnacles.
23:10By focusing on particular prey, sea otters have a balancing effect on the ecosystem.
23:17Helping to keep it healthy.
23:23Otters seem to have a relentless curiosity.
23:26To me, it's an indicator of just how intelligent they are.
23:32An endearing trait.
23:34And one that often results in play.
23:41Essential for all otters as they grow and develop.
23:49Teaching them crucial life lessons.
24:15And it's exactly what I had to do with honey.
24:18The otter I reared at home.
24:24But play for her wasn't always much fun for me.
24:29Ow! Where's my skull?
24:31Ah! Ah, come on!
24:33This whole biting my skull thing, honey.
24:36I'm not a fan.
24:37I'm not a fan.
24:42In social species, the bonds that play solidifies make otter families a formidable force.
24:52Especially important for giant river otters, who regularly face deadly predators.
24:59With vulnerable young cubs, this family discovered a large black caiman in their territory.
25:12Identifying it as a threat, they worked together.
25:15Systematically attacking it.
25:31For three hours, the otters pinned it down, taking it in turns to attack its underside and head.
25:41As a result of the caiman.
25:43As a result of the caiman.
25:56Eventually, the enormous size and power of the caiman.
26:00The caiman was no match for the family, whose bonds are so strong that they would risk dying for each
26:06other.
26:28For the orphans in Wisconsin, their best chance of the future in the wild will come from staying together.
26:35For the orphans in Wisconsin, their best chance of the future in the wild will come from staying together.
26:36They can get a lot more exercise, start doing what they need to do and start being a lot less
26:41dependent on us.
26:42And we can start cutting off our human contact with them.
26:44And so they can learn to be otters and not rely on humans too much anymore.
26:51They now have their most important piece of survival equipment.
26:57A warm, completely waterproof coat.
27:03Fur is an otter's secret weapon.
27:08They all rely on it to keep warm.
27:14But to understand its special qualities, we need to look at sea otters once again.
27:20They have the densest and most luxurious fur of any animal.
27:26It's such high quality that trappers historically measured all other fur against it.
27:32It's the main reason sea otters have been persecuted throughout their range.
27:39Their fur has nearly one million hairs per square inch.
27:47To properly appreciate the world's furriest animal, I've come to Monterey Bay Aquarium in California,
27:54whose sea otter reintroduction program has been instrumental in the recovery of the population.
28:03The aquarium's head vet, Dr. Mike Murray, has anaesthetized a female otter for a check-up,
28:09giving me a chance to take a close look.
28:13Look at the size of that.
28:15That's enormous.
28:17She actually feels really warm.
28:19That really, really thick fur they have is designed to conserve heat.
28:24And she really doesn't, without the cold water, have an opportunity to dump heat.
28:29Her coat is so effective that Dr. Mike has to put bags of ice on her flippers to stop her
28:35overheating.
28:39This is the most beautiful, silky, soft fur you can imagine.
28:44On the outside, it's much thicker.
28:46When you get down deep inside, it's just silk smooth.
28:52You can just make out the sort of pale white skin underneath.
28:58What's amazing is how wet it is on the outside and then you peel it back and it's completely dry
29:03on the inside.
29:05That's beautiful.
29:07It's so soft you can barely feel it and it's weird.
29:11And if you look at the undercoat, they've got these long guard hairs but down deep, you look at those
29:17microscopically and they've got all these little scales that stick off the shaft of the fur.
29:22And what the otter does when it grooms is it just conditions the fur and get those things to lock
29:27together.
29:28So that it becomes impenetrable to water essentially and they can get air in those spaces very similar to a
29:34down jacket or a down vest that we might be wearing.
29:39Looking at the undercoat in microscopic detail shows these scales lining the shaft of each hair.
29:46Grooming increases the volume of air trapped in this layer, maximising its insulation potential.
30:00And in the freezing waters of Alaska, survival relies on good insulation.
30:08This mother is fluffing up her baby's coat.
30:12By blowing into its fur, she's filling it with air to keep him warm.
30:20The more trapped air, the warmer it is.
30:28But for it to be effective, it needs to be kept in top condition.
30:34Which means otters spend hours each day grooming.
30:43Using their flexible spine to reach those hard to get spots.
30:54We can see just how effective their coat is with the help of some technology.
31:01This is a thermal camera.
31:03So what it does is it looks, instead of looking at a straight image of something as we'd normally look
31:07at through a camera,
31:08this looks at the heat signature of everything.
31:11So it can tell the difference between hot and cold.
31:13And it shines up here, you know, the yellow bits are warmer and the purple bits are colder.
31:19So it's going to be really interesting looking at the sea otter with this camera,
31:22because it will show me which parts of the sea otter are retaining heat
31:25and which parts of the sea otter are giving off heat.
31:28Okay, so she's right underneath me now.
31:30This is going to be a really nice shot.
31:33There she is.
31:38So you just see, looking at that, the bits that are really shining up yellow are her eyes and her
31:43mouth and her nose,
31:44just a few bits on the side of her head.
31:46So those are the main bits that are losing heat.
31:49That's amazing.
31:52What's interesting is that the water temperature here is around 7 degrees Celsius
31:57and her body temperature is around 37 degrees Celsius.
32:01So we're actually looking at a 30 degree difference between the water temperature and her body,
32:06but we're not seeing it on the picture.
32:08Her body is almost the same colour as the water.
32:13So what that means is that thick fur that the otter's got is so good at insulating the otter
32:19that very little heat is coming off it.
32:22Almost no difference between the water temperature and the temperature of the otter on the outside of the otter,
32:27because all the heat at 37 degrees is being kept inside.
32:36This highly specialised coat is one of the reasons otters are more capable on land than other semi-aquatic mammals.
32:46Like sea lions.
32:53One of the differences between these California sea lions and otters is not just the fact that they've given up
33:01their legs for flippers,
33:04but they're fat. They're great big fat lummuxing things. They're useless on land.
33:09This is pretty much the extent of what they can do on land, which is climb ashore and go to
33:14sleep.
33:15And otters, otters can be really successful predators on land.
33:18And the reason is, is they don't have any blubber.
33:21These guys use blubber to keep themselves warm in the sea.
33:24Otters use fur.
33:26And one inch of fur is the equivalent, in insulating terms, of four inches of blubber.
33:40The otters fur coat not only provides them with superb insulation in the water,
33:45it also allows them to have incredible agility on land.
33:52Something the orphans in Wisconsin will need to take advantage of.
33:58At five months old, their confidence is growing.
34:02And their curious and intelligent nature is starting to shine through.
34:07Perfect.
34:07So now what we can do is...
34:09So they know you're going to feed them, don't they?
34:10We can toss in a fish or two.
34:15And normally, as soon as you get a couple in there...
34:19Oh, look at that. Straight on it.
34:21Wow.
34:23That was, that was so far.
34:28You know what, it's so lovely to come back here and see how they've developed.
34:32I mean, they're just huge now.
34:34Compared to what they were, I mean, they were just tiny little helpless, useless otters.
34:39And back then, we were, you know, we gave them their first fish,
34:41and we thought, wow, they can catch a fish.
34:43Isn't that wonderful?
34:44Now you watch them, they're just, I mean, they're pros now.
34:47Exactly.
34:48You know, and if you look, now you have a hard time telling who the guy with the bum leg
34:52was.
34:53He doesn't show any sign of any problems anymore.
34:56He's just as good as the other ones at catching fish, and just as fast and just as agile as
35:01everybody else.
35:03I'm relieved that the injury to his back leg has recovered so well.
35:07It's testament to Mark's skills as a substitute mother.
35:11He's taking the camera in there.
35:13Look at that. There's the cameras going in.
35:16How can we get this in?
35:18They will figure it out.
35:20Oh look, he's reframed it for us.
35:24They're just into everything, aren't they?
35:25Yep. Yep.
35:26And that's otters for you, isn't it?
35:28Exactly.
35:28Crazy into everything.
35:30Everything.
35:31You know, just like this with a block there.
35:34You worry about them tipping the block over on themselves.
35:36Ooh, yeah.
35:36And, uh...
35:38Oh!
35:43There we go. We sunk the camera.
35:47They're now swimming around, looking at themselves under water in it.
35:52They're doing otter selfies.
36:00I just love their energy and determination.
36:05These guys are clearly well on the way to having the skills they'll need to survive in the wild.
36:10And that time is fast approaching.
36:13Their release into Wisconsin's northern woods is only a month away.
36:18They've got each other.
36:19They do.
36:20I mean, one otter, you know, that's tricky.
36:23Three otters together.
36:24Right.
36:25They can learn from each other.
36:26They're safer in numbers.
36:28Exactly.
36:28So, they should do pretty well.
36:31Well, they can certainly fish.
36:34Okay.
36:35So, I think we'll bug on out of here.
36:36They're starting to get a little bit too used to us.
36:38We've been trying to keep our, you know, contact to a minimum.
36:41So, let's get on out of here.
36:44Cheers, guys.
36:47Mark's intentionally keeping contact with the orphans to a minimum.
36:52They need to be as independent as possible ahead of their release.
37:03They need to be as independent as possible.
37:04Although they're doing well,
37:05catching fast, wild fish in a big open lake or flowing river
37:09will present them with an enormous challenge.
37:19They'll need to bring all their knowledge and skills together.
37:34To reveal how otters do this, I'm heading to Oakland Zoo in California,
37:39where I hope to film a hunt in super slow motion.
37:43Here, they enrich the lives of their otters by feeding them live prey.
37:49Goldfish.
37:51Helping me dissect the action is Professor of Biology, Leilani Stel.
37:56Look, check this out, Leilani.
37:58What this is going to allow us to do is actually,
38:00while the otter's swimming, I can track along with it.
38:03And it shoots in really decent slow motion.
38:06We can basically slow things down ten times.
38:08Wow.
38:09Yeah.
38:09That'll give us amazing detail on what they're doing right at the moment
38:13when they see their food and are able to catch it.
38:18Oh, he's going for it.
38:19Oh!
38:20That is nice, isn't it?
38:24Look at them chasing it together.
38:28Oh, he's having trouble getting that one.
38:30Oh, look at that!
38:33Got it.
38:35Awesome.
38:37Okay, let's have a look, see what we've got.
38:40There's the play button.
38:47Oh, that's so cool to see it in the slow motion,
38:50so you can see all the details of the moving.
38:54Because when we were watching it, it was so fast, it was hard to see.
39:01It's incredibly agile, isn't it?
39:05Yeah, you can see him do a really quick turn,
39:09and you can definitely see how flexible his spine is.
39:13So it really is, I guess, the spine's doing a load of work,
39:16and then when he needs to get the fish, the back legs seem to come out.
39:22And that's, I guess, how they get in that turn of speed.
39:28The flexible spine, combined with its tail and webbed hind feet,
39:33allow the otter's supreme agility and speed in the water.
39:40In the final approach, it uses its underwater eyesight
39:44to place the fish right in front of its head.
39:58Oh, wow.
39:58That's right on the tail of the fish, isn't it?
40:01Yeah, he kind of nudged it with his nose first.
40:03Yeah.
40:03It definitely seems like we're noticing that they're feeling the fish more than anything,
40:09and so it may be that they're detecting it with their whiskers first,
40:13and since that has a hard wire from the whiskers right to the jaw,
40:19they can just bite with instinct without having to take that time for the brain to process the signal.
40:25So they're not, you know, they're not feeling it and thinking,
40:27is that to my left, is that to my right?
40:29They're just, it's an instant.
40:30It's like us seeing or hearing.
40:32Yeah, exactly. There's no delay.
40:34Right.
40:34And that would explain how they're able to pick up on the fish so quickly,
40:38because I would have trouble seeing the fish and they would already grab it.
40:41Right. And it is incredibly fast, isn't it?
40:49As soon as the prey touches the whiskers, an incredible nervous reaction is triggered.
40:55The signal, fired to the brain, is immediately turned into a command,
41:00stimulating the jaw to grab, cutting out any decision-making delay.
41:09And it all happens in a fraction of a second.
41:18But I've spotted something else intriguing in the footage.
41:24That otter's nosing that fish and sniffing the fish, right?
41:29And if you look, when it first comes up to it, it puts bubbles out.
41:32And it's got whole loads of bubbles around its mouth.
41:35Right.
41:36Because I'm convinced otters could smell underwater.
41:38So do you think the bubbles are going back into the nose or into the mouth?
41:41I think they're going into both.
41:42Interesting.
41:43It's not improbable because a lot of animals can smell underwater, right?
41:47And it's just a chemical cue and as long as it's concentrated so it's like really right close to them,
41:53it makes sense that they would still be able to smell it underwater.
41:59So other animals that can smell underwater, do they just sniff in water or do they use bubbles in this
42:05way?
42:06You know, to be honest, I don't think anyone knows.
42:11It's thrilling to think that otters' ability to smell underwater could in fact be an undiscovered survival skill.
42:20I've long thought otters must have this secret ability and seeing this has inspired me to put my theory to
42:27the test.
42:36I'm hoping Rudy might be able to help me once again.
42:42So really the only definitive way of proving that otters can smell underwater is to do an experiment.
42:48So what we're going to do is we're going to get some fake fish and some real fish.
42:52And we're going to try and film Rudy telling the difference between the fake fish and the real fish.
42:58So what we've got here is a fake piece of plastic trout nut.
43:04So we're going to put that on here.
43:08And we present Rudy with two identical looking pieces of fish.
43:15And to see if you can tell the difference.
43:18So we're going to put this experimental block here underwater.
43:27This relies on Rudy investigating each piece underwater.
43:33Deciding which one is food and then eating it.
43:36And Rod and I capturing the whole thing on camera in slow motion.
43:46No interest in the fake one.
43:51Absolutely none.
43:58Wow. Come on Rudy. Do it.
44:03It's so fast and it's so subtle that it's very difficult to work out exactly what's going on.
44:09My camera simply isn't capable of slowing it down enough to see the finer details.
44:15But Rod's camera captures the action 40 times slower than real life.
44:22Alright Rod.
44:23Possibly. Possibly.
44:25It's so quick and obviously we're slowing it down 40 times.
44:29I think until we actually see it.
44:32Oh wow. So that's a, my God. That is a close shot. There's his head.
44:39Isn't it a bubble?
44:40That's a bubble coming out of his mouth isn't it?
44:45Oh he's sucked it back in.
44:47It's done it. It's done it. That was it.
44:49Fantastic.
44:50That's amazing.
44:52A bubble came out of his mouth and just as he was lifting his head he sucked it right back
44:57in again.
44:59It wasn't his nose but it was his mouth.
45:01He draws it back in. Hopefully tasting the fish.
45:05Which is amazing because you can actually see it happening perfectly.
45:11Rudy actively pushes a bubble onto the surface of the fish.
45:16Picking up scent molecules before he sucks it back in.
45:22Obtaining enough information to determine whether it's something he wants to eat.
45:28This footage helps me understand how otters might find food in dark murky waters where they can't rely on their
45:36underwater eyesight.
45:38They sniff it out.
45:41It's amazing to think that an animal we're so familiar with may still hold secrets from us.
45:53And good to think that the orphans may have this ability too.
45:59The cubs are six months old now and autumn's coming.
46:03It's time for their release.
46:07With his parenting nearly over, Mark has built a pen.
46:11Which he'll leave on the shores of an isolated lake.
46:16This will give the orphans somewhat familiar to come back to until they're able to fend for themselves.
46:22Off it.
46:23Wow.
46:24Here's the moment guys.
46:30Look at that.
46:36How amazing.
46:38You can't imagine what it's like.
46:40It's like having never been outside in your life really, isn't it?
46:44Exactly.
46:45All these new fun and things to explore.
46:52It's so funny.
46:53They're just into everything.
46:54They run for about ten feet and then they stop.
46:56And they look around.
46:57And then they run.
46:59They're just crazy.
47:01They're checking everything out.
47:03And checking my tripod out.
47:14You know what's lovely is the point where they get to the water.
47:18Because they're suddenly going to be otters finally.
47:22It's all very well looking like an otter.
47:24But to actually be free and be swimming and catching fish.
47:28That's the special bit.
47:52So this is the accumulation of all of our efforts coming to the end.
47:57And this is kind of the moment we've been waiting for since we started.
48:04And it gives you a lot of satisfaction to be able to see them out there swimming and doing what
48:08they're doing.
48:09And knowing that you kind of had a chance to set it right.
48:12You know for what went wrong in the first place.
48:16They'll still continue to put food out for them.
48:18But they need to find their independence now.
48:22And they're smart enough to do it.
48:24I mean you're still kind of mum, aren't you?
48:26But you're a hands off mum.
48:28Exactly.
48:29Today we cut the apron strings a little bit.
48:31Yeah.
48:33And it's obvious that the orphans are relishing their first real taste of freedom.
48:38They'll just keep expanding their range little by little and start checking things out and getting more adventurous.
48:44And eventually they'll go probably around the whole lake and not too much longer.
48:49They'll probably start heading up and down the creeks that are coming in and out and seeing what's there.
48:58In the same way a mother otter would keep catching fish for her young at this age in the wild.
49:04Until Mark is sure that they're using all their learned and innate skills, he'll keep putting out food for them.
49:11And what happens, do you stop feeding them first and then they go or do they generally just move off?
49:17They generally just move off.
49:18Yeah, so we'll offer food for a while until, you know, we notice the food's not disappearing anymore and we
49:23don't see them anymore.
49:26So it's their first night alone then?
49:28Yeah, it'll be their first night alone but I think they'll do just fine.
49:31They've had a lot of fun today and I think they're just going to find a place to go to
49:34sleep.
49:40I think they're going to sleep well.
49:42I think so too.
49:42Have they got a good supper?
49:43They should be good.
49:46As night falls, I can't help but worry for them.
49:50Although Mark's provided them with food, for the first time in their lives they will have no one looking out
49:57for them.
50:11As soon as it's light, I'm keen to check up on the orphans.
50:20But first there doesn't seem to be any sign of them.
50:32Then I hear some familiar chirps.
50:44I'm delighted.
50:45All three are foraging together.
50:57There's something about when you see a group of otters like this.
51:01You know, three otters, almost like there's one animal and three bodies.
51:05They move so perfectly, so in sync with each other.
51:10They know where each other is the whole time.
51:12They know what each other's doing.
51:14Even though sometimes they can't see each other.
51:16You know, this is really murky, peaty water.
51:20So they can't see in it, but they always know where each other is.
51:30For Mark to have gotten them from, you know, three tiny cubs to this state and put them into this
51:35place and release them so quickly and so effectively is brilliant.
51:40I think he's done a great job.
51:45Just looking at these guys from this canoe, it's just like watching a group of wild otters.
51:52And they're doing everything wild otters do.
51:53They're behaving like wild otters.
51:55They're hunting along in the reeds and the lilies along the edge of the lake.
52:01And they're foraging.
52:02That's what otters do.
52:03They're not always out in the middle of the lake speeding after a fish.
52:07Most of the time is spent nosing around in the weeds trying to find some food.
52:11And that's exactly what these guys are doing.
52:13So it makes me very hopeful.
52:15You know, you look at them behaving like real wild otters and you think, well, if you can do that
52:20within 24 hours of being released,
52:22I think the chances of survival for these guys are pretty high.
52:31Mark has given the orphans a real second chance at life.
52:36And as long as they stick together, harness everything their surrogate mum has taught them,
52:43alongside their own natural instincts, they should be able to cope with most things.
52:58I'm reassured otters have what it takes to survive.
53:02History has shown this.
53:06Where otter populations were at record lows, some are now coming back.
53:1440 years ago, the Eurasian otter was extinct across most of the UK.
53:21Now it's found in every county.
53:27And the sea otter numbered just 2,000 individuals a century ago.
53:34But with the help of protection and reintroduction programmes, it has made a population increase to 125,000.
53:48We can't get complacent.
53:50Across the globe, otters are threatened.
53:54But where they're given the chance, they can adapt to a changing world.
53:58And there's one place where they've made a very surprising comeback.
54:11Downtown Singapore.
54:19Singapore.
54:24Singapore is one of the busiest countries in the world.
54:30Attracting over 15 million visitors a year, it might not seem like a haven for wildlife.
54:38But despite the hustle and bustle, and having been thought extinct here just a few decades ago,
54:44in 2014, smooth-coated otters moved into the city centre.
54:53There are now thought to be well over 60 otters living inside the city-state.
55:01The reason?
55:03While fresh water in Singapore's Marina Bay has for the last nine years been highly protected.
55:10There's next to no fishing or pollution.
55:15The result is a vast reservoir absolutely full of fish.
55:23Perfect for otters.
55:27And now, on a daily basis, they demonstrate one of the characteristics I love most.
55:35Their close family bond.
55:43What's really freaking me out is that the last time I filmed a group of otters this big and this
55:48social and exciting
55:50was in one of the remotest parts of the Amazon.
55:53And that was a group of giant otters, or 15 of them.
55:56And now I've got 13 completely wild otters,
56:00right in the middle of, I guess, one of the most densely populated cities on Earth.
56:06And this family has just expanded Singapore's population even further.
56:13They have four 11-week-old pups.
56:22And just like the orphans in Wisconsin, they too are on a journey of survival.
56:47Pottters are very sensitive animals and they've been in trouble across the world for a long time now.
56:52But if Singapore proves anything to me, it's that they are adaptable.
56:57I've no doubt otters are survivors.
57:04For me, it's all about their supercharged nature.
57:09And I think it's this that makes me smile every time I see one.
57:15And here in Singapore, there are plenty of other smiling faces.
57:20That's because otters are special.
57:23And given the chance, we'll always make the most of what's available to them.
57:28They need nice clean water, decent supply of food, and they need to be free from persecution.
57:37And clearly, Singapore has provided them the perfect home.
57:47And that basically proves to me that these shy, nocturnal, secretive animals that we kind of all think otters are,
57:55give them the right ingredients for life, protect them, and they'll thrive.
58:19And in the weeks and months following their release, through autumn and winter, the orphans in Wisconsin are also thriving.
58:33From the secrets of seabirds to shark science, take a dip into Blue Planet UK.
58:39Later today at 4.45 here on BBC Two.
58:58Go to azathi Stars!
58:59You
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