0:00:02 > 0:00:05From the loudest roar...
0:00:05 > 0:00:09to the smallest squeak,
0:00:09 > 0:00:13all across the world, animals are talking to each other
0:00:13 > 0:00:16in extraordinary ways.
0:00:16 > 0:00:20Ever since I was little, I've wanted to become a real-life Dr Dolittle
0:00:20 > 0:00:22and talk to the animals.
0:00:22 > 0:00:24I think it's something we'd all secretly love.
0:00:26 > 0:00:31I'm Lucy Cooke, a zoologist on a quest to crack the animal code.
0:00:35 > 0:00:38New discoveries are being made all the time
0:00:38 > 0:00:43and I'm going on a worldwide journey to unravel animal conversations
0:00:43 > 0:00:46and hopefully unlock some of the secrets of their lives.
0:00:47 > 0:00:50'Using the latest scientific findings,
0:00:50 > 0:00:53'I'm going to listen in on a hidden world...'
0:00:55 > 0:00:57(My heart is going like the clappers.)
0:00:57 > 0:00:59'..from seismic chatter...'
0:00:59 > 0:01:01LOW BUZZING
0:01:01 > 0:01:03He's making that noise to attract her, is he?
0:01:03 > 0:01:05'..to flirting in the language of light.'
0:01:05 > 0:01:07I'm not just having a conversation,
0:01:07 > 0:01:08I'm chatting it up!
0:01:10 > 0:01:13I'll discover how animals communicate...
0:01:13 > 0:01:17This is the first example we know of of infrared communication.
0:01:17 > 0:01:19..and reveal exactly what they're saying.
0:01:21 > 0:01:23This is amazing! So this is a dolphin greeting.
0:01:25 > 0:01:28It's a totally secret world that I'm just listening in to.
0:01:38 > 0:01:43'Last time, I travelled across three continents
0:01:43 > 0:01:45'to find out how animals communicate
0:01:45 > 0:01:48'with their families and social groups...'
0:01:48 > 0:01:51The sounds they make, it's extraordinary.
0:01:51 > 0:01:55'..and make contact with potential partners.'
0:01:55 > 0:01:58That's unrequited love like I have never seen before.
0:02:00 > 0:02:04'So what I want to learn next is how animals communicate with
0:02:04 > 0:02:06'and about their enemies.'
0:02:11 > 0:02:14My first stop is Kenya, East Africa.
0:02:17 > 0:02:20I've come to meet an animal who has perfected the art of raising
0:02:20 > 0:02:24the alarm and calling in reinforcements...
0:02:24 > 0:02:26the spotted hyena.
0:02:27 > 0:02:31Often depicted as a cowardly scavenger,
0:02:31 > 0:02:34the laughing hyena is in fact
0:02:34 > 0:02:37one of the most successful predators in Africa.
0:02:40 > 0:02:42I love hyenas.
0:02:42 > 0:02:46They're unfairly maligned because they are really, really smart,
0:02:46 > 0:02:48intelligent animals.
0:02:50 > 0:02:53'Dr Sarah Benson-Amram works with a team who have been studying
0:02:53 > 0:02:57'the hyenas here for 25 years.'
0:02:57 > 0:02:58Tell me how their society works.
0:02:58 > 0:03:03They live in large clans and they all defend a communal territory,
0:03:03 > 0:03:07but you don't always find them all together at the same time.
0:03:07 > 0:03:10Hyenas stick together closely at night,
0:03:10 > 0:03:13but during the day, they tend to be more spread out.
0:03:13 > 0:03:17So how do they rally the troops if their territory comes under attack?
0:03:17 > 0:03:20You might hear some whoop vocalisations
0:03:20 > 0:03:23that can travel up to 5km.
0:03:23 > 0:03:26Hyenas can also distinguish individuals based on their whoop.
0:03:26 > 0:03:31So from, like, 5km away, a hyena can hear the sound
0:03:31 > 0:03:36of another hyena's whoop and recognise who that individual is?
0:03:36 > 0:03:39- Exactly.- That's amazing! Gosh.
0:03:40 > 0:03:44The whoop is one of the most common sounds hyenas make
0:03:44 > 0:03:48and can mean different things depending on the situation.
0:03:48 > 0:03:51To see what role it has in recruitment, we're going to play
0:03:51 > 0:03:58the sounds of their two main enemies, lions and rival hyenas.
0:03:58 > 0:04:02So we've located a lone female hyena and we're now going to play her
0:04:02 > 0:04:06the sound of some stranger hyenas fighting a lion
0:04:06 > 0:04:08and see what her response is.
0:04:08 > 0:04:12What we hope is going to happen is that she will start whooping
0:04:12 > 0:04:16in order to recruit her fellow clan to try and see them off.
0:04:20 > 0:04:25RECORDING OF ANIMAL CALLS
0:04:26 > 0:04:29The sounds quickly get her attention...
0:04:31 > 0:04:37RECORDING OF ANIMAL CALLS
0:04:37 > 0:04:40..and before long...
0:04:40 > 0:04:43she calls for reinforcements.
0:04:43 > 0:04:49HYENA WHOOPS
0:04:52 > 0:04:55- That's fantastic! She did it - she started whooping!- She did.
0:04:55 > 0:04:57So what she's doing is now she's shouting,
0:04:57 > 0:05:00"Come join me, everyone, come join me."
0:05:00 > 0:05:04Other clan members have heard the whoop and come straight to her aid.
0:05:04 > 0:05:06Oh, now we have a third.
0:05:06 > 0:05:08So basically, she's now trying to rally the troops
0:05:08 > 0:05:11- to go and see off the lions. - And the other hyenas.
0:05:11 > 0:05:13That was a really fascinating response.
0:05:13 > 0:05:15Once the troops have been gathered,
0:05:15 > 0:05:18the next step is to assess the threat.
0:05:19 > 0:05:23Sarah's found a way to demonstrate just how much information hyenas
0:05:23 > 0:05:27can deduce from the sound of each other's whoops.
0:05:27 > 0:05:30What we're going to do is we're going to play the sound
0:05:30 > 0:05:34of three hyenas doing their whoop call,
0:05:34 > 0:05:38but these are three hyenas that this clan doesn't know.
0:05:38 > 0:05:40What do we hope will be the reaction?
0:05:40 > 0:05:44We've seen at least six adult hyenas here, so what we hope will happen
0:05:44 > 0:05:48is that they'll pay attention to the calls, recognise that there are
0:05:48 > 0:05:51three different individuals calling, know they have the bigger group
0:05:51 > 0:05:53and then act aggressively,
0:05:53 > 0:05:56knowing that they could take on this smaller group of intruders.
0:05:56 > 0:05:59- What you're implying is that hyenas can count.- Yes.
0:05:59 > 0:06:01They have to know that, "We've heard three voices
0:06:01 > 0:06:05"and now that we are six, so we should be able to take these three."
0:06:05 > 0:06:08Wow! Well, that's hopefully what's going to happen
0:06:08 > 0:06:09if they've read the manual.
0:06:09 > 0:06:13- So we're now going to sort of launch an enemy attack.- Yes.
0:06:13 > 0:06:15Right, OK.
0:06:15 > 0:06:18RECORDING OF HYENAS WHOOPING
0:06:18 > 0:06:20Her head came up.
0:06:20 > 0:06:25RECORDING OF HYENAS WHOOPING
0:06:27 > 0:06:30Definitely got some interest now. Different hyena call.
0:06:33 > 0:06:35They're all looking up now.
0:06:37 > 0:06:39Every single hyena is looking at us.
0:06:39 > 0:06:42Oh, my word, they're coming towards us.
0:06:42 > 0:06:46They're all coming over. Wow.
0:06:46 > 0:06:48'This time, there's no attempt to call for help.
0:06:48 > 0:06:52'This group have worked out that they outnumber their rivals
0:06:52 > 0:06:56'and are keen to press home their advantage.'
0:06:56 > 0:07:01And now they're searching the area looking for the intruders.
0:07:01 > 0:07:05So that clearly demonstrates that these hyenas recognise that the
0:07:05 > 0:07:10calls that we played were strangers, they weren't from their clan.
0:07:10 > 0:07:14And they also worked out that there were few enough calling
0:07:14 > 0:07:16that they could take them on.
0:07:16 > 0:07:21The hyenas have evolved the ability to work as a team to fight off threats
0:07:21 > 0:07:25and they're not the only ones.
0:07:25 > 0:07:28It's a trait that's seen across the animal kingdom,
0:07:28 > 0:07:33but the most striking examples of this behaviour are found in birds.
0:07:37 > 0:07:40Known as mobbing, flocks have been known to take on animals
0:07:40 > 0:07:43hundreds of times their size...
0:07:46 > 0:07:50..allowing them to see off predators they could never defeat alone.
0:07:54 > 0:07:59I want to find out more about these winged armies so I've left Africa behind
0:07:59 > 0:08:03and have come to the Tahoe National Forest in California.
0:08:03 > 0:08:07I'm here to meet a bird who cannot only call for backup,
0:08:07 > 0:08:10but can articulate precise levels of danger...
0:08:10 > 0:08:13the mountain chickadee.
0:08:13 > 0:08:16Carrie Branch is going to help me listen in on them.
0:08:16 > 0:08:18BIRDS CHIRP
0:08:18 > 0:08:20- Hey, Carrie.- Oh, hi!
0:08:20 > 0:08:21- Nice to meet you.- Nice to meet you.
0:08:21 > 0:08:24- I've seen a few chickadees about. - Yes.
0:08:24 > 0:08:27- They're quite unassuming little birds, aren't they?- Yes, they are.
0:08:27 > 0:08:31I mostly love them because I love small, angry animals
0:08:31 > 0:08:34and I think of them as, like, almost the real Angry Birds.
0:08:34 > 0:08:38They're quite feisty and they have quite a bit of personality.
0:08:38 > 0:08:41They're always aware of predators that are lurking around,
0:08:41 > 0:08:43so if you come close to them, they want to check you out
0:08:43 > 0:08:46and see what you're about, as we do.
0:08:46 > 0:08:49So what's the call that we're going to listen to today?
0:08:49 > 0:08:52The call we're looking at today is what is known as a mobbing call.
0:08:52 > 0:08:56That's because when predators are present and they're perched nearby,
0:08:56 > 0:09:00what the birds do is they call a lot, just over and over again
0:09:00 > 0:09:03and the notion is that they're trying to recruit other individuals
0:09:03 > 0:09:05to help scare this predator away.
0:09:05 > 0:09:09Carrie believes that the chickadees can adapt their mobbing calls
0:09:09 > 0:09:12depending on the level of threat.
0:09:12 > 0:09:16But to see this in action, we need to find some test subjects.
0:09:16 > 0:09:21If you look through your binoculars, you can see the entrance.
0:09:21 > 0:09:22Oh!
0:09:22 > 0:09:25- So their babies are inside there? - Yes.- How old are they?
0:09:25 > 0:09:28These guys are about 18 days after hatch.
0:09:28 > 0:09:30Does that make the parents especially protective?
0:09:30 > 0:09:32For sure.
0:09:32 > 0:09:35We're going to present this family with two different levels of threat
0:09:35 > 0:09:38and record their responses to see how they compare.
0:09:40 > 0:09:42The first danger they'll face...is me.
0:09:42 > 0:09:44- BIRDS CALL LOUDLY - Oh!
0:09:47 > 0:09:50Both Mum and Dad are both calling.
0:09:51 > 0:09:54They're really plucky little birds, these.
0:09:55 > 0:09:58Definitely, definitely telling me to leave.
0:10:00 > 0:10:03Well, I've got my recording so I'm going to leave them in peace now
0:10:03 > 0:10:05so they can feed the young.
0:10:07 > 0:10:10While the chickadees have a well-earned lunch break,
0:10:10 > 0:10:13I prepare for phase two of the experiment.
0:10:13 > 0:10:15It's time to up the ante.
0:10:15 > 0:10:18OK, Carrie, so this is the bigger threat.
0:10:18 > 0:10:20- Right.- What is it? Show me what you've got.
0:10:20 > 0:10:22All right, so the bigger threat than you is...
0:10:24 > 0:10:27- Oh!- ..Harry the Cooper's hawk.
0:10:27 > 0:10:31- OK, that's a bigger threat than I am?- Oh, yeah, definitely.
0:10:31 > 0:10:33See, these birds are small, so actually smaller predators
0:10:33 > 0:10:37are more threatening to them than larger predators are.
0:10:37 > 0:10:40To a chickadee, small equals agile,
0:10:40 > 0:10:43so these birds pose the biggest threat to them and their chicks.
0:10:47 > 0:10:51But will a greater threat produce a different call?
0:10:51 > 0:10:56BIRDS CALL LOUDLY
0:11:00 > 0:11:04Wow, that's quick, there's two of them already.
0:11:04 > 0:11:08- And what do you think they're saying?- They're probably saying,
0:11:08 > 0:11:11"Holy crap! There's a big hawk right there in front of our nest."
0:11:11 > 0:11:13BIRDS CALL LOUDLY
0:11:13 > 0:11:17You can hear that this is more of a response than when I came along.
0:11:17 > 0:11:21This is a more aggressive mobbing call. This is a loud call.
0:11:23 > 0:11:24Responses recorded,
0:11:24 > 0:11:28Carrie wants to show me exactly how the two reactions differ.
0:11:28 > 0:11:30Tell me, what are we looking at here?
0:11:30 > 0:11:33So here we're looking at two different chickadee calls.
0:11:33 > 0:11:35We have the response from the hawk presentation
0:11:35 > 0:11:40and then we also have the response from the Lucy presentation,
0:11:40 > 0:11:43where you were present in front of the nest box.
0:11:43 > 0:11:46'The chickadee is named after its distinctive call,
0:11:46 > 0:11:49'which is made up of four parts.'
0:11:49 > 0:11:51Are these the different individual notes here?
0:11:51 > 0:11:53Right, so these are the different note types.
0:11:53 > 0:11:57Note A, note B, note C and then note D.
0:11:57 > 0:12:02And as you see, we have four D notes from the hawk presentation
0:12:02 > 0:12:05and then we have the same structure here
0:12:05 > 0:12:07from the response from your presence.
0:12:07 > 0:12:11We're got the A, B and C, but then you see we only have one D note.
0:12:11 > 0:12:14Let me listen to that hawk call first, then.
0:12:14 > 0:12:17CHICKADEE ALARM CALL PLAYS
0:12:17 > 0:12:21So that's the hawk call. Then here we have the Lucy call.
0:12:21 > 0:12:23SHORTER ALARM CALL PLAYS
0:12:23 > 0:12:24It's actually really clear,
0:12:24 > 0:12:27you can hear with the hawk, it's "chicka-dee-dee-dee-dee."
0:12:27 > 0:12:30Basically, they're saying, "We really need some help right now,"
0:12:30 > 0:12:34instead of, "Well, somebody's here, maybe some other birds
0:12:34 > 0:12:36"should come and help us out."
0:12:36 > 0:12:38More Ds means more danger,
0:12:38 > 0:12:40it's like a kind of exclamation mark, basically?
0:12:40 > 0:12:42Right, this is, like, extreme.
0:12:42 > 0:12:46So this tiny creature can not only warn others of danger
0:12:46 > 0:12:50but by changing the number of D notes, it can articulate exactly
0:12:50 > 0:12:53the level of threat that's faced.
0:12:53 > 0:12:56Carrie's research has found that
0:12:56 > 0:12:58the great grey owl gets two D notes,
0:12:58 > 0:13:02while the pygmy owl, despite being a quarter of the size,
0:13:02 > 0:13:05is worth an enormous 23 Ds.
0:13:07 > 0:13:10But the chickadees' chatter doesn't end there.
0:13:10 > 0:13:15Whilst only the D notes have been decoded so far,
0:13:15 > 0:13:19they can vary the number of any of the four parts that make up their call.
0:13:20 > 0:13:25This system allows the chickadees to encode a huge amount of information
0:13:25 > 0:13:28and the resulting sequences
0:13:28 > 0:13:32have even been compared to human sentences.
0:13:32 > 0:13:35I've learnt that animals have warning systems more sophisticated
0:13:35 > 0:13:37than I ever thought possible.
0:13:42 > 0:13:45Back in Africa, at Kenya's Diani Beach,
0:13:45 > 0:13:49I'm about to meet a creature who takes things one step further.
0:13:50 > 0:13:54This is a vervet monkey and it's a relatively common species
0:13:54 > 0:13:57found throughout Southern and Eastern Africa,
0:13:57 > 0:14:01but what's special about it is its place in scientific history.
0:14:01 > 0:14:04Back in the 1980s, a couple of pioneering field scientists
0:14:04 > 0:14:09started an investigation into the vervet's sophisticated alarm calls.
0:14:09 > 0:14:12As I've seen, when threatened by a predator,
0:14:12 > 0:14:14animals often sound the alarm.
0:14:16 > 0:14:19But scientists have found that vervets are able to articulate
0:14:19 > 0:14:25not only the type of threat but, incredibly, how best to avoid it.
0:14:25 > 0:14:27I want to see this in action.
0:14:27 > 0:14:30First of all, I need some predators.
0:14:36 > 0:14:39Traditionally, the vervet has three main predators...
0:14:39 > 0:14:42snakes, who hunt by stealth,
0:14:42 > 0:14:47birds of prey, which can spot a vervet from over 5km away
0:14:47 > 0:14:50and leopards, who can climb trees
0:14:50 > 0:14:53and could devour an adult vervet whole.
0:14:54 > 0:14:58Getting their real predators to play ball might be problematic,
0:14:58 > 0:15:01so I'm going to try and trick the vervets with some fakes.
0:15:02 > 0:15:05One of the vervet's major predators is the leopard
0:15:05 > 0:15:07but there haven't been any leopards around here for decades,
0:15:07 > 0:15:10so I'm going to have to improvise.
0:15:10 > 0:15:12- How much is your leopard? - 30,000.
0:15:12 > 0:15:1430,000? Ooh...
0:15:15 > 0:15:19Don't have that much. I'm wondering, can I rent it?
0:15:19 > 0:15:22- 2,000 for half a day?- Yes.- Yeah?
0:15:22 > 0:15:24- It's a deal?- It's a deal.
0:15:24 > 0:15:26Thanks, Martin.
0:15:35 > 0:15:36The question is,
0:15:36 > 0:15:40will the vervets have any reaction at all to my garden ornament?
0:15:45 > 0:15:49VERVETS JABBER
0:15:52 > 0:15:55I've just arrived and I think it's working.
0:15:55 > 0:15:59Already, I've got vervets alarm-calling at my leopard.
0:15:59 > 0:16:02VERVETS JABBER
0:16:02 > 0:16:04Well, this is fantastic.
0:16:04 > 0:16:06I didn't actually think this was going to work
0:16:06 > 0:16:09because the vervets here have never seen a leopard
0:16:09 > 0:16:14and that means to me that they must be pre-programmed to do this call.
0:16:14 > 0:16:19But alongside the distinctive calls, I notice something else.
0:16:19 > 0:16:20They're all doing the same thing.
0:16:20 > 0:16:23They're running towards the end of the branches and that's because
0:16:23 > 0:16:26they know that leopards can't chase them to the end of the branches
0:16:26 > 0:16:30and catch them, so that's the place they're safest.
0:16:30 > 0:16:33Whether this call is the monkeys shouting "Leopard!"
0:16:33 > 0:16:36or issuing the instruction to race to the end of the branches
0:16:36 > 0:16:38is unclear.
0:16:38 > 0:16:40But what is certain is that,
0:16:40 > 0:16:43despite never having seen a leopard in their lives,
0:16:43 > 0:16:47the vervets are alerting each other and have hatched an escape plan
0:16:47 > 0:16:50specifically to evade this type of predator.
0:16:52 > 0:16:55So what will happen if I change my mode of attack?
0:16:58 > 0:17:00It's time for fake foe number two.
0:17:05 > 0:17:10This time, the vervets make a completely different call...
0:17:10 > 0:17:13VERVETS CHATTER
0:17:15 > 0:17:19..and in response, the group stand up and scan the ground.
0:17:21 > 0:17:25They clearly know they need to watch their step.
0:17:25 > 0:17:28VERVETS CHATTER
0:17:28 > 0:17:31That was exactly the response that I was hoping for.
0:17:31 > 0:17:34The vervet in the tree gave off the alarm call which is,
0:17:34 > 0:17:37"Danger, stand up, look about."
0:17:37 > 0:17:41Which is exactly what the vervets did and that's because snakes
0:17:41 > 0:17:44basically hunt by stealth, so if you're a vervet and you don't
0:17:44 > 0:17:47want to get eaten, your best tactic is to spot the snake,
0:17:47 > 0:17:50because once they've spotted it, the snakes move pretty slowly,
0:17:50 > 0:17:54they don't hunt fast and so they're likely to survive an attack.
0:17:56 > 0:18:00I've had two good results today. There's just one enemy left.
0:18:00 > 0:18:05It was all going swimmingly until the rain started.
0:18:05 > 0:18:08This rain came out of nowhere.
0:18:08 > 0:18:11I don't know where the monkeys are, but if they're like me,
0:18:11 > 0:18:13then they're also seeking shelter somewhere.
0:18:14 > 0:18:16Rain stops play.
0:18:16 > 0:18:18THUNDER RUMBLES
0:18:22 > 0:18:26Eventually, there's a break in the downpour.
0:18:26 > 0:18:29Given the fact that we've been waiting for the last four hours
0:18:29 > 0:18:33for the rain to stop, this might be the best situation that I have
0:18:33 > 0:18:35to see if I can at least get a call out of them.
0:18:37 > 0:18:42I want to see how the vervets respond to an aerial attack...
0:18:42 > 0:18:45and I'm hoping my hawk kite might do the trick.
0:18:50 > 0:18:52Well, that's quite frustrating, actually.
0:18:52 > 0:18:58What one would expect when a vervet sees a hawk, the textbook response
0:18:58 > 0:19:03is to make a call and then to run into the centre of the tree.
0:19:03 > 0:19:06Instead, these ones are just running into the centre of the tree
0:19:06 > 0:19:08and not making any kind of calls.
0:19:09 > 0:19:13Maybe I've been too subtle in my approach.
0:19:29 > 0:19:32VERVET CHIRPS
0:19:32 > 0:19:36I think... It was hard to tell, but I think I heard
0:19:36 > 0:19:41a little couple of solitary chirp noises coming from them.
0:19:41 > 0:19:46That is vervet code for, "Danger, take cover."
0:19:46 > 0:19:49It means run into the centre of the trees because that's where
0:19:49 > 0:19:54you're most likely to be able to avoid being attacked by the hawk.
0:19:54 > 0:19:58So what's interesting is that each of those responses and the calls
0:19:58 > 0:20:00have been quite different.
0:20:00 > 0:20:04What science has shown is that vervets have specific calls
0:20:04 > 0:20:07which relate to different predators
0:20:07 > 0:20:11and seem to have a strategy for dealing with each one.
0:20:11 > 0:20:13VERVET CHIRPS
0:20:13 > 0:20:17"Danger, hawk! Run for cover to the centre of the tree."
0:20:19 > 0:20:22VERVET CHATTERS
0:20:22 > 0:20:25"Danger, snake! Stand up and scan."
0:20:27 > 0:20:29VERVET JABBERS
0:20:29 > 0:20:34"Danger, leopard! Head for the end of the branches."
0:20:34 > 0:20:37Well, my equipment may have been a bit basic,
0:20:37 > 0:20:41but I've still clearly seen that vervet alarm-calls are much more
0:20:41 > 0:20:44than a one-size-fits-all kneejerk reaction to fear
0:20:44 > 0:20:46like a human scream.
0:20:46 > 0:20:49And they're actually a bit more like words,
0:20:49 > 0:20:53symbolic signals that contain specific information.
0:20:53 > 0:20:56A bit like when we shout, "fire!" or "shark!"
0:20:56 > 0:20:58but with a more detailed escape plan.
0:21:00 > 0:21:03Vervets were the first animals in the world whose alarms calls
0:21:03 > 0:21:06were shown to mean different things.
0:21:06 > 0:21:10This discovery opened the floodgates.
0:21:10 > 0:21:13For years, biologists had assumed that these calls
0:21:13 > 0:21:15were simple screams of terror.
0:21:17 > 0:21:20Today, we know that a huge variety of animals
0:21:20 > 0:21:23encode different information in their alarms.
0:21:23 > 0:21:29Chickens have different warnings for aerial and ground attacks.
0:21:31 > 0:21:36The ring-tailed lemur has eight different types of alarm call
0:21:36 > 0:21:39and the prairie dog even describes the colour
0:21:39 > 0:21:41and size of its predators.
0:21:43 > 0:21:48Calls which have all evolved to try and help outwit their adversaries.
0:21:53 > 0:21:57I've seen first-hand that animals have extremely complex methods
0:21:57 > 0:22:01of communicating with their own kind.
0:22:01 > 0:22:05But 8,000 miles away in Central America lives a creature
0:22:05 > 0:22:07who's learnt to tune in to the language
0:22:07 > 0:22:10of another species altogether.
0:22:10 > 0:22:13This is the fringe-lipped bat.
0:22:13 > 0:22:17The skies here in Panama are filled with flying spies,
0:22:17 > 0:22:21eavesdropping on other animal conversations with deadly results.
0:22:23 > 0:22:25Bats are extremely social animals
0:22:25 > 0:22:29and are constantly in contact with the other members of their colony.
0:22:29 > 0:22:32But because they communicate at ultrasonic frequencies,
0:22:32 > 0:22:35normally they're completely inaudible to humans.
0:22:37 > 0:22:41So I've met up with Dr Rachel Page, a leading expert in bat-chat,
0:22:41 > 0:22:43who's going to help me listen in.
0:22:45 > 0:22:50So this gadget here, this enables us to snoop on the bats?
0:22:50 > 0:22:51How does it work, then?
0:22:51 > 0:22:52So this is a bat detector.
0:22:52 > 0:22:56It takes a high frequency and it'll translate it into a lower frequency.
0:22:56 > 0:22:59So a frequency we can't hear cos it's in the ultrasound
0:22:59 > 0:23:01and turn it into one that's audible to our own ears.
0:23:01 > 0:23:06So this way we get to hear what we would never normally hear.
0:23:06 > 0:23:07LOW FREQUENCY CRACKLE
0:23:07 > 0:23:11'This bat has been making these noises the whole time.
0:23:11 > 0:23:15'Only by converting them into a lower frequency
0:23:15 > 0:23:17'are we able to hear him speak.'
0:23:17 > 0:23:21It's a totally secret world that I'm just listening in to.
0:23:22 > 0:23:26Animals have developed sensitivity to different frequencies
0:23:26 > 0:23:28depending on their requirements.
0:23:28 > 0:23:31Elephants can use low frequency rumbles
0:23:31 > 0:23:33to communicate over vast distances...
0:23:33 > 0:23:36ELEPHANT EMITS LOW GRUMBLE
0:23:36 > 0:23:38..whereas bats communicate over a smaller area,
0:23:38 > 0:23:42but need more detail, so use high frequencies.
0:23:44 > 0:23:47What we can't tell from the bat detector just from listening
0:23:47 > 0:23:49is how loud they are. They're actually...
0:23:49 > 0:23:51In the frequency that the bat is transmitting,
0:23:51 > 0:23:53they're very, very loud.
0:23:53 > 0:23:56So if that equivalent loudness was at a frequency we could hear,
0:23:56 > 0:23:57it would be deafening.
0:23:57 > 0:23:59No, really?
0:23:59 > 0:24:02So they're basically flying along, screaming their heads off.
0:24:02 > 0:24:04The loudest species of bats recorded
0:24:04 > 0:24:08have been up to 140 decibels, which is extremely loud.
0:24:08 > 0:24:13As in humans, sounds are detected by the bat's ear as vibrations
0:24:13 > 0:24:17and transmitted by the nervous system straight to the brain.
0:24:17 > 0:24:21Almost all animals receive sound in the same frequency range
0:24:21 > 0:24:23that they broadcast on.
0:24:24 > 0:24:28Because they transmit at a higher end of the sound spectrum,
0:24:28 > 0:24:33it was assumed that bats couldn't detect noises made at a lower range.
0:24:33 > 0:24:38But it seems that the fringe-lipped bat has learned to eavesdrop.
0:24:38 > 0:24:41Scientists noticed that they seemed to be able to find
0:24:41 > 0:24:46and identify frogs with huge accuracy,
0:24:46 > 0:24:50even in the dense, dark surroundings of the rainforest they live in.
0:24:51 > 0:24:55The only explanation is that the bats have developed sensitivity
0:24:55 > 0:24:57to a second frequency band.
0:24:57 > 0:25:03They may be pre-set to Radio Bat but they're tuning in to Frog FM.
0:25:03 > 0:25:09So do all bats eavesdrop on frogs or is it just this particular one?
0:25:09 > 0:25:12- This is the only bat in the world that does this.- Really? Wow.
0:25:12 > 0:25:17So it seems like it's specially adapted to eavesdrop on frog calls.
0:25:17 > 0:25:19To show this eavesdropping in action,
0:25:19 > 0:25:22Rachel has devised an experiment.
0:25:22 > 0:25:25Obviously, we don't want to put a real frog in harm's way,
0:25:25 > 0:25:29so we're going to use Robofrog, a made-to-measure model.
0:25:29 > 0:25:32ROBOFROG CHIRPS
0:25:34 > 0:25:36Above him is the bat.
0:25:36 > 0:25:40If this bat really is a spy and can speak frog,
0:25:40 > 0:25:44we're about to find out because as soon as I press the call button,
0:25:44 > 0:25:47he should wake up and fly down and get the frog. Here we go.
0:25:50 > 0:25:51ROBOFROG CHIRPS
0:25:51 > 0:25:55We're doing the experiment in the dark as that's when bats hunt.
0:25:55 > 0:25:58ROBOFROG CHIRPS
0:25:58 > 0:26:02Oh! Look, his ears are going, his ears are going!
0:26:02 > 0:26:04They're really turning, aren't they?
0:26:14 > 0:26:17Yay, he did it, he did it.
0:26:17 > 0:26:20- He did.- That is amazing.
0:26:21 > 0:26:26What makes it even more impressive is that the bat isn't just locating
0:26:26 > 0:26:31the frog from its call, it's also deducing the size and toxicity.
0:26:33 > 0:26:36There are almost 200 types of poisonous amphibian
0:26:36 > 0:26:39in South and Central America.
0:26:39 > 0:26:43The fringe-lipped bat has learned to recognise the calls of toxic species
0:26:43 > 0:26:46so that their frog supper doesn't prove fatal.
0:26:48 > 0:26:53So eavesdropping is an incredibly useful survival skill and these bats
0:26:53 > 0:26:59are sonic spies that have learned to crack the frog code to stay alive.
0:26:59 > 0:27:03I've met an animal which listens in on the language of its prey.
0:27:05 > 0:27:08But now scientists have discovered that there's a creature
0:27:08 > 0:27:11who's actually learned to talk back.
0:27:11 > 0:27:15I've travelled 3,000 miles to the Californian hills.
0:27:17 > 0:27:19This place may look peaceful
0:27:19 > 0:27:22but it's home to one of the most dangerous reptiles
0:27:22 > 0:27:24in North America...
0:27:24 > 0:27:25the rattlesnake.
0:27:27 > 0:27:30These ambush predators are cleverly camouflaged
0:27:30 > 0:27:35and stealthy in their approach, so I need to take precautions.
0:27:35 > 0:27:37I'm not taking any chances.
0:27:37 > 0:27:39I've never met a rattlesnake before,
0:27:39 > 0:27:42but I'm guessing they're not very friendly.
0:27:42 > 0:27:44This is one of our research animals,
0:27:44 > 0:27:48one of our captive rattlesnakes that we use to simulate an interaction.
0:27:48 > 0:27:52Dr Rulon Clark has been studying the snake and its enemies
0:27:52 > 0:27:53for the last 12 years.
0:27:55 > 0:27:57SNAKE'S TAIL RATTLES
0:27:57 > 0:28:01You see, he's a little bit alarmed but still fairly docile, actually.
0:28:01 > 0:28:05You can see he's in this tube and his head, the dangerous part
0:28:05 > 0:28:09of his body, is all the way up here and is restrained by the plastic.
0:28:09 > 0:28:12- He's perfectly safe. - Can I touch it?- Sure.
0:28:12 > 0:28:15It's really cold. He's got to be...
0:28:15 > 0:28:19- I don't know, feels like 10, 15 degrees cooler than me?- Yes.
0:28:19 > 0:28:23'This cold-blooded killer could easily take down a human,
0:28:23 > 0:28:27'but the rattlesnake has his eye on a different prize...
0:28:27 > 0:28:29'the ground squirrel,
0:28:29 > 0:28:33'a small rodent which is common in North American scrublands.'
0:28:33 > 0:28:36So how much of this snake's diet would be made up of ground squirrel?
0:28:36 > 0:28:40Almost 70%, 80%. Some of the snakes around here, we've never seen them
0:28:40 > 0:28:43eat anything or hunt for anything other than ground squirrels.
0:28:43 > 0:28:46So to help locate their favourite food,
0:28:46 > 0:28:49the snake has evolved an extraordinary ability.
0:28:49 > 0:28:53You can actually see in-between his nostril, the end of his nose there,
0:28:53 > 0:28:56and his eye, there's that little pit in his face.
0:28:56 > 0:29:01That pit has a heat sensing membrane in it. They can see heat with that.
0:29:01 > 0:29:04In exactly the same way their eyes detect light,
0:29:04 > 0:29:08these pits detect heat as particles of infrared radiation.
0:29:10 > 0:29:14Combining these visual and thermal images allows the snake to track
0:29:14 > 0:29:17its prey with pinpoint accuracy.
0:29:17 > 0:29:20And that makes it all the easier to catch squirrels?
0:29:20 > 0:29:26Yes, they have an extrasensory perception of warm-blooded animals.
0:29:26 > 0:29:29They'll see them at dark, they'll see them at night.
0:29:29 > 0:29:33They'll see them more vividly when there's grass obstructing them.
0:29:33 > 0:29:34Things like that.
0:29:34 > 0:29:36- So it's like a super-sense?- Yes.
0:29:38 > 0:29:41So we're about to do an experiment to see exactly what happens
0:29:41 > 0:29:45in a stand-off between a rattlesnake and a ground squirrel.
0:29:46 > 0:29:50On one side, we have a top predator that hunts by stealth,
0:29:50 > 0:29:53can see in the dark and has a powerful venomous bite.
0:29:55 > 0:29:57And on the opposing side is an animal
0:29:57 > 0:29:59who could best be described as...
0:29:59 > 0:30:00fluffy.
0:30:01 > 0:30:05But the ground squirrel has found a way to fight back.
0:30:05 > 0:30:09In order to get a snake's-eye view of the encounter, we're going to
0:30:09 > 0:30:13use this specialised camera that can actually see heat.
0:30:18 > 0:30:21Here comes the squirrel. You got the thermal?
0:30:23 > 0:30:27So this dark blue cold-blooded blob here,
0:30:27 > 0:30:28that's the snake?
0:30:28 > 0:30:31And this orange figure darting around, that's the squirrel?
0:30:31 > 0:30:34Yes, exactly, you can see how warm the squirrel is.
0:30:34 > 0:30:37See how warm his body is? It's kind of brighter orange.
0:30:38 > 0:30:42You can see he's coming in and he's waving his tail.
0:30:42 > 0:30:46Look how warm his tail is getting when he does some of this waving.
0:30:46 > 0:30:49It's almost as warm as his body and occasionally he has these
0:30:49 > 0:30:53flashes of heat in it that are even warmer than his body.
0:30:53 > 0:30:56Yes, you can, you can see it suddenly flashes up orange
0:30:56 > 0:30:58inside the tail.
0:30:58 > 0:31:01So this is a specialised form of communication.
0:31:01 > 0:31:04It's just to talk to a rattlesnake.
0:31:04 > 0:31:08So they have a specialised way of sending a message to a rattlesnake
0:31:08 > 0:31:11using heat or infrared light which is only something
0:31:11 > 0:31:13that a rattlesnake can see.
0:31:13 > 0:31:16By pumping warm blood into its tail,
0:31:16 > 0:31:19the squirrel is sending a message directly to the rattlesnake.
0:31:21 > 0:31:24"I know you're here. The ambush has failed."
0:31:25 > 0:31:28Is this the first time anyone has ever seen an animal
0:31:28 > 0:31:30use infrared in this way?
0:31:30 > 0:31:32Yes, this is the first example we know of
0:31:32 > 0:31:35of infrared communication in animals.
0:31:35 > 0:31:40How do you know that he doesn't just do this all the time anyway?
0:31:40 > 0:31:43If you watch how these squirrels interact with a gopher snake,
0:31:43 > 0:31:48which is a different snake predator, their tail temperature is different.
0:31:48 > 0:31:52They don't heat it up and gopher snakes can't see infrared light.
0:31:52 > 0:31:56The fact that the squirrel only does this when the recipient
0:31:56 > 0:31:59of their communication can actually see it indicates that it's
0:31:59 > 0:32:04specially evolved to send a message to this particular type of animal.
0:32:04 > 0:32:07That's such a finely-tuned piece of evolution, isn't it?
0:32:07 > 0:32:09Yes, it's amazing, isn't it?
0:32:09 > 0:32:12It's just one aspect in this whole co-evolutionary process
0:32:12 > 0:32:14between these two animals.
0:32:14 > 0:32:18This squirrel has developed an extraordinary survival skill,
0:32:18 > 0:32:22a language created specifically to speak to its enemy.
0:32:23 > 0:32:27Squirrels and rattlesnakes have been locked in an epic evolutionary
0:32:27 > 0:32:29battle for about 10 million years
0:32:29 > 0:32:33and this creation of a novel infrared communication system
0:32:33 > 0:32:37is just the latest in a long line of attack and counterattack moves.
0:32:37 > 0:32:40And it can't help but make me wonder
0:32:40 > 0:32:43what kind of crazy super-power might evolve next.
0:32:46 > 0:32:49When staying alive is at stake,
0:32:49 > 0:32:53animals have developed extremely complex forms of communication.
0:32:56 > 0:33:00But what I want to look at next is whether they're as sophisticated
0:33:00 > 0:33:04when it comes to talking to those closest to them.
0:33:06 > 0:33:10Having friends is often thought of as a uniquely human trait.
0:33:13 > 0:33:18But recent findings have started to suggest that it's an important part
0:33:18 > 0:33:20of animals' lives, too.
0:33:20 > 0:33:23To find out more, I've come back to the UK
0:33:23 > 0:33:26to visit a Sussex University research site.
0:33:26 > 0:33:31Professor Karen McComb studies the social lives of horses.
0:33:31 > 0:33:34What is a horse's social circle like?
0:33:34 > 0:33:39Their core social group is a group of females who aren't relatives.
0:33:39 > 0:33:41That's the interesting thing, they're not related,
0:33:41 > 0:33:43and they hang out with their stallion.
0:33:43 > 0:33:47They have particular individuals that they spend more time with,
0:33:47 > 0:33:51so sort of the equivalent of human friends.
0:33:51 > 0:33:56They like spending time with certain individuals over others.
0:33:56 > 0:33:58Whether you're human or horse,
0:33:58 > 0:34:03it's been shown that having friends can bring huge health benefits.
0:34:03 > 0:34:06But do they think of them in the same way that we do?
0:34:06 > 0:34:09As humans, we take it for granted that when we hear the voice
0:34:09 > 0:34:13of someone we know, say, on the end of the phone, we conjure up an image
0:34:13 > 0:34:15of that person in our mind.
0:34:15 > 0:34:19Now, this ability was long thought to be unique to mankind.
0:34:19 > 0:34:24So the big question is, can animals do the same thing?
0:34:24 > 0:34:26Karen believes that horses can conjure up
0:34:26 > 0:34:28mental images of other horses,
0:34:28 > 0:34:30even when they're not around.
0:34:30 > 0:34:33So this here is Pepsi.
0:34:33 > 0:34:36This is Lance, here, and on the end that's Fi
0:34:36 > 0:34:39and these horses are all pretty good mates.
0:34:39 > 0:34:42They've been sharing stables and grazing together
0:34:42 > 0:34:43for about six and a half years.
0:34:43 > 0:34:49So they're all very aware of each other's voices and their faces.
0:34:49 > 0:34:51In order to show that horses can conjure a mental picture
0:34:51 > 0:34:55of their friends, we're going to do an experiment.
0:34:55 > 0:34:58Fi has been taken back to her stable,
0:34:58 > 0:35:01leaving Lance and Pepsi alone in the field.
0:35:01 > 0:35:04So first up, if Lance ever stops eating,
0:35:04 > 0:35:08is we're going to show him Pepsi, his stable-mate,
0:35:08 > 0:35:12and then we're going to take Pepsi behind the horsebox
0:35:12 > 0:35:15and play Pepsi's whinny.
0:35:15 > 0:35:17Stop Pepsi there, perfect.
0:35:17 > 0:35:20Come on, Lance, you need to take a good look, drink in Pepsi.
0:35:21 > 0:35:25Yes, he's clocked that Pepsi's there, for sure.
0:35:25 > 0:35:26Say goodbye to Pepsi, Lance.
0:35:26 > 0:35:31- Off she goes.- Jane's taking Pepsi in behind the horsebox,
0:35:31 > 0:35:34the horsebox simply acting as a barrier here,
0:35:34 > 0:35:37so Pepsi is now going to disappear from sight.
0:35:37 > 0:35:39Pepsi is gone.
0:35:41 > 0:35:44I'm just going to play Pepsi's whinny.
0:35:44 > 0:35:47RECORDING OF PEPSI'S WHINNY
0:35:48 > 0:35:51So he's a bit interested but not overly bothered.
0:35:51 > 0:35:53That's what he was expecting.
0:35:53 > 0:35:57He saw Pepsi and he just heard Pepsi's whinny there,
0:35:57 > 0:35:58so he's gone back to grazing.
0:35:58 > 0:36:02We'll see what happens when Pepsi's whinny sounds again.
0:36:02 > 0:36:03RECORDING OF PEPSI'S WHINNY
0:36:03 > 0:36:05- He's just not bothered. - He's not bothered.
0:36:05 > 0:36:08What he saw matched what he heard
0:36:08 > 0:36:12and he's just getting on with what he was doing before.
0:36:12 > 0:36:14As far as Lance is concerned,
0:36:14 > 0:36:17Pepsi is the only other horse nearby,
0:36:17 > 0:36:21so how will he react when we play Fi's call instead?
0:36:21 > 0:36:25This time it's not going to be Pepsi's whinny,
0:36:25 > 0:36:27it's going to be a whinny from Fi.
0:36:32 > 0:36:35RECORDING OF FI'S WHINNY
0:36:35 > 0:36:38Now, he looked very quickly there. Keep a loose rein on him.
0:36:40 > 0:36:42So he's still looking...
0:36:44 > 0:36:45..and he's still listening.
0:36:45 > 0:36:48Do you see the way his ears are pricked and very attentive?
0:36:48 > 0:36:50He's still paying attention to that.
0:36:52 > 0:36:53He definitely gave a reaction.
0:36:53 > 0:36:58'Lance's response may not have been massive but the implications are.
0:36:58 > 0:37:04'For him to react in surprise suggests that he has advanced cognitive abilities.'
0:37:04 > 0:37:08When he saw Pepsi, he was expecting to hear Pepsi's whinny
0:37:08 > 0:37:11because his mental picture of Pepsi is quite complex.
0:37:11 > 0:37:15It's got what Pepsi looks like, also what Pepsi sounds like,
0:37:15 > 0:37:17maybe what Pepsi smells like
0:37:17 > 0:37:21and the voice he heard didn't match the mental picture.
0:37:21 > 0:37:24'The idea that animals think in the same way we do
0:37:24 > 0:37:27'is truly ground-breaking,
0:37:27 > 0:37:29'fundamentally rewriting our understanding
0:37:29 > 0:37:32'of how their minds work.'
0:37:32 > 0:37:36It gives us the first indication that animals really do have pictures
0:37:36 > 0:37:41of others in their minds that's complex in the way that ours is.
0:37:41 > 0:37:44Karen's research suggests that horses can maintain mental images
0:37:44 > 0:37:47of at least 30 friends...
0:37:47 > 0:37:51and they aren't the only animals who have wide social circles.
0:37:51 > 0:37:55Sheep can recognise the faces of 50 of their flock,
0:37:55 > 0:37:58and remember them for over two years.
0:37:58 > 0:38:02Elephants can recognise up to 100 voices.
0:38:02 > 0:38:06That's the same number of friends the average person has on Facebook.
0:38:07 > 0:38:10I want to find out more about the communication that's evolved
0:38:10 > 0:38:14to support these animal friendships.
0:38:14 > 0:38:17So I've come to Scotland to meet one of the most social
0:38:17 > 0:38:20and talkative animals on the planet...
0:38:20 > 0:38:22the bottlenose dolphin.
0:38:23 > 0:38:27We know that, like us, relationships are really important to dolphins
0:38:27 > 0:38:31yet they live in this vast, featureless landscape so,
0:38:31 > 0:38:35if you're a dolphin, how do you keep up with your friends?
0:38:38 > 0:38:40My guide today is Dr Vincent Janik,
0:38:40 > 0:38:44one of the world's leading experts in dolphin communication.
0:38:44 > 0:38:49- So how easy are they to find, these dolphins?- That's a good question.
0:38:49 > 0:38:51- It's different every day.- Right.
0:38:51 > 0:38:53So, normally they're kind of in this area here,
0:38:53 > 0:38:55so this is the mouth of the Tay.
0:38:55 > 0:38:57This is the area we see them the most.
0:39:03 > 0:39:07'Luckily for me, it isn't long before a school appears.'
0:39:07 > 0:39:09I just saw a big splash over there, like a really big splash.
0:39:14 > 0:39:15Wahoo!
0:39:18 > 0:39:22What is it about seeing dolphins that just makes you so happy?
0:39:25 > 0:39:26Wonderful.
0:39:28 > 0:39:32As it is for us, dolphin communication is wide-ranging.
0:39:32 > 0:39:36We know that they use touch and body language,
0:39:36 > 0:39:38but in the limited visibility of the sea,
0:39:38 > 0:39:42it's sound that is the most important.
0:39:42 > 0:39:44'But to decode some dolphin chatter,
0:39:44 > 0:39:47'we need to record a group interacting
0:39:47 > 0:39:51'and Vincent has an underwater microphone to help me listen in.'
0:39:52 > 0:39:55This is the hydrophone that's going to enable us to hear
0:39:55 > 0:39:57what the dolphins are saying.
0:40:01 > 0:40:07So hydrophones are in the water which means that if I turn this on,
0:40:07 > 0:40:10it will reveal the underwater world.
0:40:10 > 0:40:14HIGH-PITCHED WHISTLING
0:40:19 > 0:40:21You can hear the whistles!
0:40:23 > 0:40:25Suddenly the mysteries of the deep revealed.
0:40:28 > 0:40:32These whistles may be unintelligible to us, but by analysing them closely
0:40:32 > 0:40:37over the last 20 years, Vincent has deduced something extraordinary...
0:40:37 > 0:40:40We have two different whistles here that you can hear.
0:40:40 > 0:40:43..that dolphins have names.
0:40:43 > 0:40:46So this is two animals exchanging who they are
0:40:46 > 0:40:48before they're getting together.
0:40:48 > 0:40:51This is amazing, so this is a dolphin greeting.
0:40:51 > 0:40:53HIGH-PITCHED WHISTLING
0:40:55 > 0:40:57Vincent's research has given us an incredible insight
0:40:57 > 0:40:59into dolphin communication.
0:40:59 > 0:41:02By playing signature whistles and carefully monitoring which
0:41:02 > 0:41:07dolphin responded, they deduced that each individual has its own name.
0:41:07 > 0:41:10Those are very special because these guys
0:41:10 > 0:41:11actually developed them themselves.
0:41:11 > 0:41:14So every animal invents its own whistle after it's born
0:41:14 > 0:41:16- in the first few months of its life.- Fabulous.
0:41:16 > 0:41:20That's such a fantastic thing that they choose their own names.
0:41:20 > 0:41:23- "This is me for my life." - Yeah.- That's wonderful.
0:41:23 > 0:41:26But what's even more remarkable is that they can copy
0:41:26 > 0:41:29and broadcast the names of others in order to make contact...
0:41:29 > 0:41:33HIGH-PITCHED WHISTLING
0:41:33 > 0:41:34..just like we do.
0:41:36 > 0:41:39It's the first time this trait has been shown conclusively
0:41:39 > 0:41:41in any animal other than humans.
0:41:41 > 0:41:43So why do you think
0:41:43 > 0:41:45it's so important that dolphins have evolved names?
0:41:45 > 0:41:48One of the interesting aspects about their life is that
0:41:48 > 0:41:51their social lives are kind of similar to humans as well.
0:41:51 > 0:41:53We live in something that's called a fission-fusion society
0:41:53 > 0:41:56and what that means is that people like to be together.
0:41:56 > 0:41:58They're not always together, they sometimes go apart
0:41:58 > 0:42:01and then come back again so it's fission and then fusion again.
0:42:01 > 0:42:05Because they lead this life, they need to have a great way
0:42:05 > 0:42:09- of recognising each other just by listening.- Yes.
0:42:09 > 0:42:12It's a very effective system to stay in touch.
0:42:12 > 0:42:15And the dolphins aren't the only ones chatting constantly
0:42:15 > 0:42:16below the surface.
0:42:19 > 0:42:22Sound travels four times faster in water than it does in air,
0:42:22 > 0:42:27so for many marine animals, the sea gives them a super-fast connection
0:42:27 > 0:42:29to their friends worldwide.
0:42:29 > 0:42:30FISH THUMPS
0:42:30 > 0:42:33Some fish make drumming noises to attract a mate...
0:42:33 > 0:42:35WHALE SINGS
0:42:35 > 0:42:39..and whales have conversations that can span entire oceans...
0:42:41 > 0:42:47..with individual calls known to reach from the Caribbean to Canada.
0:42:47 > 0:42:50Dolphin social lives are a lot like ours.
0:42:50 > 0:42:53They are dynamic and ever-changing.
0:42:53 > 0:42:55We might start the day with family, then go to work,
0:42:55 > 0:42:57then finish the day with friends.
0:42:57 > 0:43:00Dolphins are doing more or less the same thing, but they're doing it
0:43:00 > 0:43:04without any regular hang-outs like home or the office.
0:43:04 > 0:43:06But by evolving individual names,
0:43:06 > 0:43:10they manage to find and maintain relationships even in the dark.
0:43:10 > 0:43:13HIGH-PITCHED WHISTLING
0:43:14 > 0:43:18I've seen for myself that animals are constantly thinking about
0:43:18 > 0:43:21and talking to their nearest and dearest.
0:43:22 > 0:43:25But for the final leg of my journey,
0:43:25 > 0:43:27I want to see how animals communicate with the different
0:43:27 > 0:43:30species they share their habitats with.
0:43:30 > 0:43:33So how do animals speak to their neighbours?
0:43:35 > 0:43:38I've come here to the Kalahari Desert in South Africa
0:43:38 > 0:43:40to investigate a surprising relationship
0:43:40 > 0:43:46between two very different species with communication at its core.
0:43:47 > 0:43:51The Kalahari covers almost a million square kilometres
0:43:51 > 0:43:54and is home to huge variety of animals...
0:43:54 > 0:43:57both great and small.
0:44:00 > 0:44:02These are the meerkats and...
0:44:02 > 0:44:05Looking very intently from side to side.
0:44:05 > 0:44:10They're incredibly anxious animals, always looking around for predators
0:44:10 > 0:44:14or rival gangs and they spend their lives foraging
0:44:14 > 0:44:16with their heads in the sand.
0:44:16 > 0:44:20And that way they're more vulnerable so they really need a neighbour
0:44:20 > 0:44:23to watch out for them.
0:44:23 > 0:44:25Enter the fork-tailed drongo.
0:44:27 > 0:44:31This bird may look unremarkable
0:44:31 > 0:44:35but Dr Tom Flower believes they're anything but ordinary.
0:44:35 > 0:44:37Drongos provide a sentry service
0:44:37 > 0:44:40and by that I mean that they are the eyes on the skies, as it were.
0:44:40 > 0:44:42When meerkats have got their heads down digging,
0:44:42 > 0:44:45the drongo is looking out and often is the first to spot predators.
0:44:45 > 0:44:47So the drongo then makes an alarm call
0:44:47 > 0:44:50and the meerkats eavesdrop on that and all dash to cover.
0:44:50 > 0:44:53So the drongo is quite a handy neighbour for the meerkat to have.
0:44:53 > 0:44:55It definitely is.
0:44:55 > 0:44:57So tell me about the experiment we're going to do today, Tom.
0:44:57 > 0:45:01Now we could hang around and wait for a hawk or an eagle to fly by,
0:45:01 > 0:45:03hope that the drongo spots it first and makes an alarm call.
0:45:03 > 0:45:06However, we'd probably be here for a very long time.
0:45:06 > 0:45:09So to encourage the drongo to issue a warning...
0:45:09 > 0:45:12Let's go and set up the experiment.
0:45:12 > 0:45:14..Tom's choreographed his own aerial attack.
0:45:19 > 0:45:22Here we are, stuffed by my own fair hand.
0:45:22 > 0:45:25This is a little juvenile male who'd been hit by a car
0:45:25 > 0:45:27and, sadly, passed away.
0:45:27 > 0:45:29He's now being put to good use as a zombie falcon.
0:45:29 > 0:45:33That's incredible, I'm so impressed that you've got an actual falcon.
0:45:33 > 0:45:36I thought you'd have a model.
0:45:36 > 0:45:38'To bring this bird back to life,
0:45:38 > 0:45:40'we're going to attach it to a zip-wire.'
0:45:44 > 0:45:47- Yes, that's good. - We just need to do a last check.
0:45:47 > 0:45:52- The meerkats are over there.- Tick. - The falcon is up there.
0:45:52 > 0:45:56- The drongo is just there.- Yeah. - So let's see what happens.
0:45:56 > 0:46:00Hopefully, he'll alarm at that and then the meerkats will dash to cover.
0:46:00 > 0:46:02- OK.- Ready?
0:46:02 > 0:46:04One, two, three...
0:46:06 > 0:46:08There he goes!
0:46:08 > 0:46:10DRONGO CRIES OUT
0:46:13 > 0:46:15- That was success. - It absolutely was.
0:46:15 > 0:46:16They've all dashed to a bolthole
0:46:16 > 0:46:18and they're all sitting there looking around now.
0:46:18 > 0:46:22That's because they've heard the drongo call.
0:46:22 > 0:46:24- So the sound that I heard... - That's one of the drongo's alarms
0:46:24 > 0:46:26that they make at predators.
0:46:26 > 0:46:29That call is only ever made when they see a predator.
0:46:31 > 0:46:32So we've just seen the drongos
0:46:32 > 0:46:36behaving a bit like a meerkat neighbourhood watch scheme.
0:46:36 > 0:46:38But it's not that simple...
0:46:38 > 0:46:41cos the drongo has a dark side.
0:46:42 > 0:46:44Tom has noticed that they sometimes make an alarm call
0:46:44 > 0:46:47even when there's no threat.
0:46:47 > 0:46:48DRONGO CRIES OUT
0:46:48 > 0:46:52The meerkats scatter in panic...
0:46:52 > 0:46:56leaving the drongo to swoop in and snatch what's left of their lunch.
0:46:56 > 0:47:00It's the first time a bird has been conclusively shown to be using
0:47:00 > 0:47:04alarm calls specifically to deceive another species.
0:47:06 > 0:47:11So if the meerkat is being deceived by the drongo on a regular basis,
0:47:11 > 0:47:13how does he not wise up?
0:47:13 > 0:47:16Well, they do. That's the problem for the drongo is that its own alarm
0:47:16 > 0:47:21stops working very quickly, just like the story, The Boy Who Cried Wolf.
0:47:21 > 0:47:23However, the drongo's got a trick up its sleeve,
0:47:23 > 0:47:26because it can mimic the alarms of other species.
0:47:26 > 0:47:28By using the warning call of others,
0:47:28 > 0:47:31which the meerkats also associate with danger,
0:47:31 > 0:47:33the drongo is back in business.
0:47:33 > 0:47:38So when one call stops working, it switches to the next type of call
0:47:38 > 0:47:40and, sure enough, the meerkats are deceived again.
0:47:40 > 0:47:43So whilst many of the animals here in the Kalahari
0:47:43 > 0:47:45understand other languages,
0:47:45 > 0:47:48the drongo is the only one that can speak other languages.
0:47:48 > 0:47:53That's right and that's the key to their deceptive success.
0:47:53 > 0:47:57The drongo is the ultimate identity thief.
0:47:57 > 0:48:00They have 30 different calls,
0:48:00 > 0:48:0415 of which have been stolen from other species,
0:48:04 > 0:48:08from the lilac-breasted roller to the pied babbler.
0:48:08 > 0:48:12While other animals, such as pigs and chimps, have been known
0:48:12 > 0:48:15to deliberately deceive others,
0:48:15 > 0:48:17the drongo is the only animal we know of
0:48:17 > 0:48:22which can change its tactics to keep up the con.
0:48:22 > 0:48:25In order to see this crafty bird swap disguises,
0:48:25 > 0:48:29Tom's come up with a test subject who can be easily manipulated.
0:48:29 > 0:48:31Meet the Womble.
0:48:33 > 0:48:35No, no, no, no! Sorry, I'm chasing the sound man. Come back...
0:48:35 > 0:48:38- LUCY GASPS - Shoot!
0:48:38 > 0:48:40It did actually take seven goes for me to pass my driving test.
0:48:40 > 0:48:43I didn't tell you that.
0:48:43 > 0:48:45- I've got it. It's coming back. - Watch out for the mini camera.
0:48:45 > 0:48:48I've brought the whole thing back in reverse. OK.
0:48:48 > 0:48:50There you go, which is good.
0:48:50 > 0:48:52- Check that out.- Beautiful.
0:48:52 > 0:48:57So, Tom's Womble is a slightly eccentric creation
0:48:57 > 0:49:02but it's going to show us how the drongo hones his deception skills.
0:49:03 > 0:49:07First of all, I'm going to load up the worms. I'll do this bit for you.
0:49:10 > 0:49:13The Womble is carrying some tasty treats.
0:49:13 > 0:49:17But will the drongo try to trick it, just as it does with the meerkats?
0:49:17 > 0:49:19There we are, stop there.
0:49:19 > 0:49:23I'm now going to drop the worms.
0:49:24 > 0:49:26Are you interested, Mr Drongo?
0:49:26 > 0:49:28You need to alarm to get those worms.
0:49:28 > 0:49:31DRONGO CRIES OUT Now run, go, go go.
0:49:35 > 0:49:39- That call was a mimic of a lilac-breasted roller.- Oh, really?
0:49:39 > 0:49:41Absolutely. That "crrr" kind of call.
0:49:41 > 0:49:44But what happens if that one stops working?
0:49:44 > 0:49:45OK.
0:49:50 > 0:49:52Having worked last time,
0:49:52 > 0:49:55the drongo tries his luck again with the same call...
0:49:55 > 0:49:58DRONGO CRIES OUT
0:49:58 > 0:50:00..but the Womble refuses to budge.
0:50:00 > 0:50:03as far as the drongo is concerned,
0:50:03 > 0:50:06this alarm call is no longer trusted...
0:50:06 > 0:50:10so he switches strategies and imitates another bird,
0:50:10 > 0:50:12- the Marico flycatcher. - DRONGO WHISTLES
0:50:16 > 0:50:18So that's fascinating.
0:50:18 > 0:50:20He totally changed his tactic when it didn't work.
0:50:20 > 0:50:24When he got no response from the Womble, he changed what
0:50:24 > 0:50:27he was doing in order to get the response that he wanted.
0:50:27 > 0:50:30Exactly and that's how he can keep his racket going.
0:50:30 > 0:50:33Just like the boy who cried wolf, his alarm does stop working,
0:50:33 > 0:50:35but then he mimics something else.
0:50:35 > 0:50:38That's the genius behind this bird, isn't it?
0:50:38 > 0:50:41That's how he manages to do something that no other animal
0:50:41 > 0:50:46is known to do and be able to keep deceiving the same animal simply
0:50:46 > 0:50:50because he's got this repertoire of calls that he uses so tactically.
0:50:50 > 0:50:51That's correct.
0:50:51 > 0:50:55So far, the only place where the drongos have been shown to do this
0:50:55 > 0:50:57is here in the Kalahari.
0:50:57 > 0:51:00With food scarce in this desert landscape,
0:51:00 > 0:51:04the drongo has adapted to give itself the best chance of survival.
0:51:04 > 0:51:063..2..1..
0:51:06 > 0:51:09Tom's findings so far are fascinating,
0:51:09 > 0:51:11but his work is far from over.
0:51:12 > 0:51:16It will be a truly ground-breaking discovery to show that animals,
0:51:16 > 0:51:20like humans, use communication to intentionally manipulate
0:51:20 > 0:51:24the minds of others, and one that strikes at the very core
0:51:24 > 0:51:27of what separates humans from other animals.
0:51:28 > 0:51:31Tom's got a lifetime's Wombling out here in the desert in order
0:51:31 > 0:51:35to crack it but I've no doubt that if anyone can do it,
0:51:35 > 0:51:37I think Tom can.
0:51:40 > 0:51:43My adventure into the world of animal communication
0:51:43 > 0:51:45is almost at an end.
0:51:46 > 0:51:50But back in Kenya, there's one last set of neighbours I want to meet
0:51:50 > 0:51:54and they're the most remarkable pairing of all.
0:51:54 > 0:51:56I set out on this journey to learn how to talk to animals
0:51:56 > 0:51:59and I've met some brilliant scientists
0:51:59 > 0:52:01who've shown me how they do it.
0:52:01 > 0:52:04But in the grand scheme of things, science has only just started
0:52:04 > 0:52:06to have these conversations.
0:52:06 > 0:52:10Here in the Masai Mara, humans have been talking to one particular
0:52:10 > 0:52:13animal for thousands of years.
0:52:14 > 0:52:17This is the greater honeyguide,
0:52:17 > 0:52:21a bird which has learned to speak to humans.
0:52:21 > 0:52:23- Hello, Moses?- Moses, yeah.
0:52:23 > 0:52:26- Moses, hello, nice to meet you. Hi, there.- Nice to meet you.
0:52:26 > 0:52:29- Hello, what's your name?- Musanga. - Musanga? Lovely to meet you.
0:52:29 > 0:52:31- Mancha.- Mancha? OK, good to meet you all.
0:52:31 > 0:52:34- So you're going to teach me about the honeyguide?- Yes.
0:52:34 > 0:52:36How do you get the honeyguide to come to you?
0:52:36 > 0:52:38We whistle for the bird like...
0:52:38 > 0:52:41- HE WHISTLES TWICE - Hiih.
0:52:41 > 0:52:44- SHE WHISTLES TWICE - Very good.
0:52:44 > 0:52:47And then what did you do? You went "ahh" afterwards?
0:52:47 > 0:52:48- Hiih.- Hiih. Hiih.
0:52:48 > 0:52:50- SHE WHISTLES - Hiih.
0:52:50 > 0:52:52All right then, let's go and get ourselves some honey.
0:52:52 > 0:52:54Yes, let's try our best today.
0:52:54 > 0:52:59For the Masai, locating a beehive in the vast plains could take weeks.
0:52:59 > 0:53:01But with the honeyguide's help,
0:53:01 > 0:53:04the time spent searching can be drastically reduced.
0:53:04 > 0:53:08THEY ALL WHISTLE
0:53:08 > 0:53:10Hiih!
0:53:12 > 0:53:15- Hiih! - Listen for a minute.
0:53:16 > 0:53:18What sound am I listening for?
0:53:18 > 0:53:21Chh-chh-chh-chh.
0:53:21 > 0:53:23That's the sound of the honeyguide.
0:53:28 > 0:53:30- You hear nothing? - Absolutely nothing.
0:53:30 > 0:53:33Just the sound of the wind in the trees.
0:53:35 > 0:53:38BIRD SINGS
0:53:38 > 0:53:39- That's a different bird.- Oh.
0:53:41 > 0:53:44My whistle's going to run out if we have to do this much longer.
0:53:45 > 0:53:46Come to us, honeyguide.
0:53:48 > 0:53:50- What's that bird?- That's not it.
0:53:50 > 0:53:52That's not it. OK.
0:53:53 > 0:53:55(Not it.)
0:53:57 > 0:54:02After hours of searching, our persistence finally pays off.
0:54:02 > 0:54:04THE BIRD CHITTERS
0:54:04 > 0:54:06- Where is it? Where is it? - Over there.
0:54:06 > 0:54:09- It's on this tree.- Oh!- There we go.
0:54:09 > 0:54:12THE BIRD CHITTERS
0:54:12 > 0:54:15We've found the bird.
0:54:15 > 0:54:19'This is a call that they only use to communicate with humans.'
0:54:22 > 0:54:24'He's telling us to follow his lead.'
0:54:27 > 0:54:29'The honeyguide has exceptional eyesight
0:54:29 > 0:54:33'and can scour far greater distances than the Masai could cover.'
0:54:33 > 0:54:36THE BIRD CHITTERS
0:54:36 > 0:54:42'We follow the distinctive call through the scrubland...
0:54:42 > 0:54:45'and finally, we arrive at a hive.'
0:54:47 > 0:54:49Oh, my goodness, there's bees in there.
0:54:50 > 0:54:54But why would a bird go out of its way to help humans?
0:54:54 > 0:54:58'The answer lies with the aggressive African bee.'
0:54:59 > 0:55:03The honeyguide wants the beeswax and grubs from within the nest,
0:55:03 > 0:55:06but its stings could be fatal to a bird this small.
0:55:08 > 0:55:11'So they've entered into a mutually beneficial relationship
0:55:11 > 0:55:15'with the Masai, who can harvest the honeycomb for them.'
0:55:16 > 0:55:19These African bees definitely are very, very, very dangerous bees.
0:55:19 > 0:55:21They're very aggressive.
0:55:28 > 0:55:29He's outrageously brave,
0:55:29 > 0:55:32sticking his hand in the hive like that.
0:55:37 > 0:55:40I'm holding this to protect myself from getting stung by the hundreds
0:55:40 > 0:55:43of angry bees that have now exited that tree.
0:55:46 > 0:55:49Oh, my goodness me, there are thousands of bees!
0:55:51 > 0:55:54The honeyguide has fulfilled his side of the bargain.
0:55:54 > 0:55:58We're going to lay some honeycomb out for it,
0:55:58 > 0:56:01which is apparently part of the etiquette.
0:56:01 > 0:56:03'Now it's our turn.'
0:56:09 > 0:56:11With the honeyguide happy,
0:56:11 > 0:56:13we can finally enjoy the fruits of out labour.
0:56:18 > 0:56:20This had better be good.
0:56:22 > 0:56:23Sweet?
0:56:23 > 0:56:26Mmmm!
0:56:26 > 0:56:31- Delicious.- That is the sweetest honey I've ever had.
0:56:31 > 0:56:33There are very few examples of animals
0:56:33 > 0:56:35working co-operatively with humans.
0:56:35 > 0:56:39Some dolphins have been spotted helping fishermen in Brazil,
0:56:39 > 0:56:41but the honeyguide's ability to talk to us
0:56:41 > 0:56:45in order to achieve a shared goal is almost unique.
0:56:45 > 0:56:49I've been all around the world, meeting top communication scientists
0:56:49 > 0:56:53in order to talk to animals, but it's here in the Masai Mara
0:56:53 > 0:56:57that I've been part of the most profound conversation,
0:56:57 > 0:57:00one that's been going on for thousands of years
0:57:00 > 0:57:04and is truly beneficial for both man and bird.
0:57:04 > 0:57:07And to have been involved in that dialogue
0:57:07 > 0:57:10has been really, really humbling.
0:57:17 > 0:57:21My journey is almost over but I've discovered that animal communication
0:57:21 > 0:57:25is so much more sophisticated than I could ever have imagined.
0:57:28 > 0:57:32Animals are sending complicated messages, not just to their own kind
0:57:32 > 0:57:36but to entirely different species and even to us.
0:57:41 > 0:57:45It's touching to discover that animals strive to stay connected
0:57:45 > 0:57:48to a wide social circle of family and friends.
0:57:50 > 0:57:53But what's most impressive are the extraordinary systems they've
0:57:53 > 0:57:58evolved to broadcast information and stay in touch.
0:57:58 > 0:58:01I started this journey with a question.
0:58:01 > 0:58:03Can we really talk to the animals?
0:58:03 > 0:58:07And now I know the answer is yes.
0:58:07 > 0:58:09We have started that conversation.
0:58:12 > 0:58:16And if science keeps advancing the way that is,
0:58:16 > 0:58:20then the potential for that dialogue is truly astonishing.