0:00:11 > 0:00:13You can see them from space -
0:00:13 > 0:00:18a mysterious network of pathways carved in the Kalahari sand.
0:00:26 > 0:00:29They are the imprint of a hundred generations of elephants
0:00:29 > 0:00:32who've walked unhindered across this landscape.
0:00:38 > 0:00:43But the current generation of elephants in Botswana is walking into an extraordinary crisis.
0:00:43 > 0:00:50Numbers here are growing rapidly, and some experts believe there are too many elephants.
0:00:50 > 0:00:54To sort out the problem, they are proposing drastic action.
0:01:09 > 0:01:10GUNSHOT
0:01:20 > 0:01:23Dr Mike Chase is an independent ecologist
0:01:23 > 0:01:26who has dedicated the last eight years to studying elephants.
0:01:26 > 0:01:31Working with leading conservation groups, governments and farmers,
0:01:31 > 0:01:34Mike is trying to avert the looming crisis.
0:01:34 > 0:01:39The fate of as many as 60,000 elephants may depend on what his research reveals.
0:01:51 > 0:01:56In June and July, the dry season takes hold of the land.
0:01:56 > 0:01:57Thousands of elephants
0:01:57 > 0:02:00are forced towards the few sources of water that remain.
0:02:06 > 0:02:10These are on their way to the Chobe River, on Botswana's northern border,
0:02:10 > 0:02:14where they will converge into the largest gathering of elephants on the continent.
0:02:17 > 0:02:21Elsewhere in Africa, elephants are in decline, but in Botswana,
0:02:21 > 0:02:24largely due to far-sighted conservation efforts,
0:02:24 > 0:02:26elephants are doing well.
0:02:29 > 0:02:31Too well, perhaps.
0:02:32 > 0:02:36The population here is officially estimated at 150,000...
0:02:40 > 0:02:43and it's doubling every 15 years.
0:02:51 > 0:02:54TRUMPETING
0:03:14 > 0:03:17Experts are worried that the elephants will soon destroy
0:03:17 > 0:03:19the fragile ecosystems on which they,
0:03:19 > 0:03:22and so much other wildlife, depend.
0:03:23 > 0:03:28Some scientists look at gatherings like this and predict environmental catastrophe.
0:03:35 > 0:03:39There have even been calls for a pre-emptive cull,
0:03:39 > 0:03:42literally shooting 60,000 elephants.
0:03:49 > 0:03:53Mike Chase is horrified by this idea.
0:03:53 > 0:03:56He's a native of this land.
0:03:56 > 0:03:59He grew up in the bush, where his fascination for elephants began,
0:03:59 > 0:04:02and he's spent most of his life
0:04:02 > 0:04:05watching and studying these gentle giants.
0:04:05 > 0:04:08Mike is concerned by the rise in elephant numbers,
0:04:08 > 0:04:12but he also thinks there's more to the problem than meets the eye.
0:04:12 > 0:04:15He suspects that numbers here are artificially high,
0:04:15 > 0:04:17that many of these elephants
0:04:17 > 0:04:20are refugees from surrounding countries,
0:04:20 > 0:04:24driven to Botswana's safe haven by civil war and poaching.
0:04:26 > 0:04:28Also, Mike believes that it's impossible to make
0:04:28 > 0:04:31an accurate assessment of the elephant problem,
0:04:31 > 0:04:33based on this temporary gathering at the Chobe River.
0:04:36 > 0:04:39During the dry season we can see thousands of elephants coming to
0:04:39 > 0:04:44quench their thirst along this river, but in the wet season they disappear.
0:04:44 > 0:04:47You can come here and for days on end not see an elephant.
0:04:49 > 0:04:52Elephants are arguably the most well-studied animals
0:04:52 > 0:04:56on the African continent, but we know so little about their movements.
0:04:56 > 0:04:59Their movements remain a mystery and here in Botswana,
0:04:59 > 0:05:02where we have the largest wilderness area left
0:05:02 > 0:05:04for elephants to roam over,
0:05:04 > 0:05:06we knew so little.
0:05:08 > 0:05:10Mike has made it his mission to investigate
0:05:10 > 0:05:12these uncharted elephant travels,
0:05:12 > 0:05:18and the question of elephant numbers before drastic decisions are made,
0:05:18 > 0:05:22and certainly before anyone considers shooting elephants.
0:05:24 > 0:05:29To start filling in these critical information gaps,
0:05:29 > 0:05:31Mike first needs to find out where elephants go
0:05:31 > 0:05:34once they leave places like the Chobe,
0:05:34 > 0:05:36and how they use the food and water resources
0:05:36 > 0:05:37during the rest of the year.
0:05:41 > 0:05:43Only then will it be possible to know
0:05:43 > 0:05:46whether there are too many elephants in Botswana.
0:05:50 > 0:05:54Botswana is a vast landlocked country the size of Franc...
0:05:56 > 0:06:00..and more than 80% of the land is covered by the Kalahari.
0:06:05 > 0:06:08Mike's initial aerial survey of the known elephant range,
0:06:08 > 0:06:12which extends thousands of square miles to the south of the Chobe,
0:06:12 > 0:06:15gives him a picture of the sheer scale and diversity
0:06:15 > 0:06:16of their surroundings.
0:06:18 > 0:06:21But as Mike flies back and forth across the Kalahari,
0:06:21 > 0:06:24he becomes aware of something extraordinary.
0:06:27 > 0:06:30One of the amazing things I noticed from the air
0:06:30 > 0:06:32were these incredible highways,
0:06:32 > 0:06:36this extensive network of ancient elephant pathways,
0:06:36 > 0:06:41that link all the waterholes like a string of pearls across the desert.
0:06:46 > 0:06:51If I could discover how elephants move along this huge web of pathways,
0:06:51 > 0:06:55perhaps I'd be able to understand their survival strategy.
0:06:59 > 0:07:04How do they find the scarce and widespread resources of the Kalahari?
0:07:09 > 0:07:12The only way Mike can unlock these secrets
0:07:12 > 0:07:15is by fitting radio tracking collars to as many elephants as he can.
0:07:15 > 0:07:19These collars will do the long-distance detective work,
0:07:19 > 0:07:24storing precise information about the elephants' movements.
0:07:29 > 0:07:33I started by collaring several young elephant bulls.
0:07:33 > 0:07:38We know from studies elsewhere that they range much further than females,
0:07:38 > 0:07:44and I hoped they would provide the most interesting and dramatic movement results.
0:07:44 > 0:07:48We found this young male at the extreme edge of the elephant range,
0:07:48 > 0:07:52about as far from the Chobe as elephants can get.
0:07:53 > 0:07:57For me, it's always an incredible experience
0:07:57 > 0:08:00to work up close with these gentle giants.
0:08:00 > 0:08:06I'm never really comfortable having to immobilise an elephant, but I remind myself
0:08:06 > 0:08:09that these few individuals will ultimately be helping
0:08:09 > 0:08:11tens of thousands of other elephants.
0:08:11 > 0:08:18I hoped that this young bull might provide priceless information.
0:08:18 > 0:08:21I decided to call him Max.
0:08:22 > 0:08:26Mike hopes that the daily GPS co-ordinates stored in Max's unit,
0:08:26 > 0:08:28and those of the other elephants
0:08:28 > 0:08:31he's collared, will tell him how elephants
0:08:31 > 0:08:34navigate around this complex network of pathways.
0:08:34 > 0:08:38What he has to do is locate Max every three months or so,
0:08:38 > 0:08:40then he can download the data.
0:08:45 > 0:08:47Until then, Mike spends time
0:08:47 > 0:08:50staking out a few well-known elephant drinking places.
0:08:52 > 0:08:56I've spent a lot of time studying bulls at their regular waterholes,
0:08:56 > 0:08:59but in the months that followed,
0:08:59 > 0:09:04I was surprised I didn't see Max at any of these usual places.
0:09:04 > 0:09:08I began to get the feeling that he might be a real wanderer.
0:09:14 > 0:09:17Once teenage males leave their maternal herds,
0:09:17 > 0:09:20they join up with other bulls, constantly exploring,
0:09:20 > 0:09:23and learning where to find food and water.
0:09:28 > 0:09:31For a few years they will journey with the bachelor herds,
0:09:31 > 0:09:35but soon the more adventurous of the young bulls break away,
0:09:35 > 0:09:37to follow their own path.
0:09:44 > 0:09:46The question for Mike is -
0:09:46 > 0:09:50how are they able to make the most of these scattered resources
0:09:50 > 0:09:51in order to survive?
0:09:53 > 0:09:56He hopes that Max will provide the answers.
0:10:02 > 0:10:05Nearly four months after he was collared,
0:10:05 > 0:10:07Mike attempts to find Max from the air.
0:10:10 > 0:10:14He can detect Max's collar from about 20 miles away,
0:10:14 > 0:10:18but that's a tiny range in this immense landscape.
0:10:22 > 0:10:25Time is critical, because soon the data stored in the collar
0:10:25 > 0:10:28will begin to overwrite itself.
0:10:28 > 0:10:34There's a great urgency to find Max and download this location data that is embedded and stored in his collar
0:10:34 > 0:10:37to better understand how these young bulls
0:10:37 > 0:10:41are moving across this landscape.
0:10:41 > 0:10:46We haven't been able to find him now for at least three to four months.
0:10:46 > 0:10:48Either his collar has failed,
0:10:48 > 0:10:52he's wondered into an area that is very remote or...
0:10:55 > 0:10:56you know, I...
0:10:59 > 0:11:04It's just horrible not knowing where he is, and every time I land without having found
0:11:04 > 0:11:06or picked up a signal from him,
0:11:06 > 0:11:08I just feel really disheartened and upset.
0:11:16 > 0:11:20Mike may have more luck with the females he has collared.
0:11:20 > 0:11:25Family groups make up over 90% of the growing elephant population,
0:11:25 > 0:11:29so if there is any impact on this fragile desert environment,
0:11:29 > 0:11:31it's likely to be caused by them.
0:11:38 > 0:11:43This is Bontle, the leader of a typical Botswana family group.
0:11:43 > 0:11:47She's one of the females carrying a newer type of tracking collar,
0:11:47 > 0:11:50which records a GPS waypoint every two hours.
0:11:50 > 0:11:55Not only will it tell Mike in much more detail where she goes,
0:11:55 > 0:11:58but it's a collar that also makes her easier to find.
0:12:01 > 0:12:05Now Mike can follow these elephants after they leave the Chobe River
0:12:05 > 0:12:08and witness first hand their journey into the desert interior.
0:12:11 > 0:12:15As the summer rains begin, they start heading south,
0:12:15 > 0:12:17and the pressure of elephant numbers
0:12:17 > 0:12:21is lifted from seasonal rivers like the Chobe.
0:12:21 > 0:12:24Heading out along hundreds of different pathways, Bontle
0:12:24 > 0:12:29and the other family groups fan out into the immensity of the Kalahari.
0:12:30 > 0:12:34Summer thunderstorms here are incredibly localised,
0:12:34 > 0:12:37bringing small areas of the desert to life.
0:12:42 > 0:12:44Rain may collect in one shallow pan,
0:12:44 > 0:12:47while leaving others nearby completely dry.
0:12:49 > 0:12:53Some of these precious waterholes may be over 30 miles apart.
0:13:01 > 0:13:04Female elephants cannot go for more than three days without drinking.
0:13:09 > 0:13:13In the relentless heat, they have to keep journeying to survive.
0:13:16 > 0:13:21Whenever he can, Mike tracks Bontle and the other collared females,
0:13:21 > 0:13:23following their long journey into the elephant heartland.
0:13:28 > 0:13:30It's up to the matriarchs, like Bontle,
0:13:30 > 0:13:34to lead their families to distant, scattered sources of food and water.
0:13:37 > 0:13:40Even in the so-called wet season,
0:13:40 > 0:13:43the Kalahari remains harsh and unforgiving.
0:13:45 > 0:13:49The desert pans are dotted far and wide across the landscape,
0:13:49 > 0:13:52linked by the web of elephant highways.
0:14:04 > 0:14:07Time and time again, Mike witnesses their remarkable ability,
0:14:07 > 0:14:11as matriarchs choose a route which bypasses empty waterholes
0:14:11 > 0:14:14but which leads, unfailingly, to full ones.
0:14:14 > 0:14:17INAUDIBLE
0:14:25 > 0:14:26Every small pool is a lifeline.
0:14:32 > 0:14:33Look how they are running in...
0:15:17 > 0:15:20This little elephant is only a few hours old.
0:15:24 > 0:15:27His mother would have given birth in the middle of the desert,
0:15:27 > 0:15:31so he may already have walked many miles to reach here.
0:15:33 > 0:15:36It's the first water he's ever seen.
0:15:42 > 0:15:45The stop at this pool will give him the day or two he needs
0:15:45 > 0:15:47to find his feet.
0:16:07 > 0:16:11He's already socialising with members of other herds,
0:16:11 > 0:16:13and even the great old bulls who come here.
0:16:31 > 0:16:35Mike believes that the little calf won't forget this experience,
0:16:35 > 0:16:38that the memory of this waterhole is now embedded
0:16:38 > 0:16:39in the youngster's mind.
0:16:54 > 0:16:57But once this water's gone, the tiny calf has no option
0:16:57 > 0:17:01but to follow his family for many miles to the next pan.
0:17:17 > 0:17:21The Kalahari is about as hostile as it gets for an elephant.
0:17:21 > 0:17:23But if there's one thing I've learned
0:17:23 > 0:17:28from years of watching elephants, it's how incredibly intelligent,
0:17:28 > 0:17:30resourceful and adaptable they are.
0:17:33 > 0:17:37I'm convinced that elephants remember key pathways and places,
0:17:37 > 0:17:42and continue to create a mental map over a lifetime.
0:17:44 > 0:17:48A calf is at the beginning of this process.
0:17:48 > 0:17:53Every day it adds to its mental map, as it follows the elders around.
0:17:56 > 0:18:00Older, wiser members of the herd are effectively passing on
0:18:00 > 0:18:01a detailed body of knowledge -
0:18:01 > 0:18:07the pathways to food and water, and the timing through the seasons,
0:18:07 > 0:18:10which have allowed that particular family to survive here
0:18:10 > 0:18:12over many generations.
0:18:19 > 0:18:21The collars are giving Mike a greater insight
0:18:21 > 0:18:23into elephant behaviour,
0:18:23 > 0:18:26and in some cases leading him to new discoveries.
0:18:28 > 0:18:32A GPS message takes him to a place he's never been to before -
0:18:32 > 0:18:36a waterhole right in the middle of the Kalahari.
0:18:36 > 0:18:38Dozens of major elephant highways
0:18:38 > 0:18:41seem to converge here from every direction.
0:19:01 > 0:19:02It's so extraordinary.
0:19:06 > 0:19:11I've never seen so many elephants around a small little pan.
0:19:11 > 0:19:14I mean, all around us here
0:19:14 > 0:19:18and there, more elephants. About 200 to our right.
0:19:18 > 0:19:20We're just surrounded by them.
0:19:22 > 0:19:26In the middle of this extraordinary gathering of 5,000 elephants
0:19:26 > 0:19:29is the one who's inadvertently led him there.
0:19:29 > 0:19:31Kel, I can see Bontle!
0:19:31 > 0:19:34Right there, right there!
0:19:34 > 0:19:36Hey, big girl!
0:19:39 > 0:19:41She's got a calf, she's got a calf, she's got a calf!
0:19:44 > 0:19:47Man!
0:19:47 > 0:19:49That's so cool. And we would
0:19:49 > 0:19:51never had found this place had it not been for her.
0:19:51 > 0:19:53I mean, here at Chinamba,
0:19:53 > 0:19:56right in the middle of the elephant heartland.
0:19:56 > 0:19:59She must have journeyed hundreds of kilometres to get here.
0:20:05 > 0:20:07Hey...
0:20:07 > 0:20:08brilliant, man.
0:20:12 > 0:20:18Bontle and all the other matriarchs have ignored good waterholes nearby.
0:20:18 > 0:20:22What's drawn so many families to this particular pan?
0:20:23 > 0:20:27This has to be more than just a coincidence.
0:20:27 > 0:20:28I began to realise
0:20:28 > 0:20:33that there must be a deliberate intention to this congregation.
0:20:33 > 0:20:36That not only do they all know how to get here,
0:20:36 > 0:20:39but also the timing of the others' arrival.
0:20:39 > 0:20:44It seems that they're thinking beyond their own family experience,
0:20:44 > 0:20:47and suggests an elephant intellect
0:20:47 > 0:20:50far more complex than we might have imagined.
0:20:54 > 0:20:57Mike believes that they may be directly communicating
0:20:57 > 0:20:58and sharing information,
0:20:58 > 0:21:03or networking in some way, that may have long-term survival benefits.
0:21:09 > 0:21:12He thinks this kind of clan group might be an important event
0:21:12 > 0:21:14in an elephant's life.
0:21:14 > 0:21:17When bonds are reinforced between family groups,
0:21:17 > 0:21:21vital decisions are made and survival strategies are shared.
0:21:25 > 0:21:28Bontle is part of this concentration,
0:21:28 > 0:21:31and Mike hopes the information being stored in her collar
0:21:31 > 0:21:35might some day help to explain this remarkable gathering.
0:21:37 > 0:21:40But there are very few bulls here.
0:21:40 > 0:21:44Where are they while the female clan groups are assembling?
0:21:44 > 0:21:46If he can find the elusive Max,
0:21:46 > 0:21:50Mike might be able to answer that question.
0:21:50 > 0:21:54He has searched the elephant heartland for Max,
0:21:54 > 0:21:57and exhausted all ideas.
0:21:57 > 0:22:00Now he needs fresh inspiration.
0:22:20 > 0:22:23There is ancient wisdom in this land,
0:22:23 > 0:22:27a wisdom born of a harsh and primeval environment.
0:22:31 > 0:22:35The San Bushman people have walked the Kalahari for a very long time,
0:22:35 > 0:22:38long before anyone ever drew lines on a map.
0:22:40 > 0:22:43Their intimate knowledge of the land and the animals
0:22:43 > 0:22:45has been critical to their survival.
0:22:47 > 0:22:50This knowledge is passed down the generations
0:22:50 > 0:22:53by the shamans and great storytellers.
0:22:55 > 0:22:58Perhaps their wisdom could add valuable information
0:22:58 > 0:22:59to Mike's research,
0:22:59 > 0:23:03and maybe even help him find Max.
0:23:06 > 0:23:10Mike decided to visit one of these traditional storytellers.
0:23:13 > 0:23:16A family friend he's known since he was a boy.
0:23:22 > 0:23:26I met with Xguka at the most sacred site
0:23:26 > 0:23:29in San Bushman culture, the Tsodilo Hills,
0:23:29 > 0:23:31that rise out of the western desert,
0:23:31 > 0:23:34beyond the known elephant range.
0:23:35 > 0:23:40She led me to extraordinary rock paintings of elephants
0:23:40 > 0:23:43that lived here thousands of years ago.
0:23:43 > 0:23:48Xguka knows that elephants still remember these remote places
0:23:48 > 0:23:50and how to survive here.
0:23:53 > 0:23:57She assured me that, like the San Bushman storytellers,
0:23:57 > 0:24:01elephants have handed down their knowledge through the generations.
0:24:14 > 0:24:17Xguka talked late into the night,
0:24:17 > 0:24:21telling me stories of how elephants travel far and wide,
0:24:21 > 0:24:25and how they make ancient pilgrimages
0:24:25 > 0:24:28to visit the lands of their ancestors.
0:24:28 > 0:24:34And she encouraged me to venture much further in my search for Max.
0:24:38 > 0:24:42The bushmen have their own explanation for extraordinary elephant movements.
0:24:42 > 0:24:47And Mike is eager to put his scientific thinking aside for a while,
0:24:47 > 0:24:50and journey into the unknown.
0:25:18 > 0:25:24Following Xguka's advice, Mike explores the Makgadikgadi salt pans,
0:25:24 > 0:25:29an immense and hostile desert, far south of the current elephant range.
0:25:30 > 0:25:34It's somewhere he's never really thought of looking for elephants.
0:25:34 > 0:25:38And yet he finds clear signs of elephant bulls,
0:25:38 > 0:25:41trekking across this vast infinity of salt.
0:25:44 > 0:25:49These tracks are not necessarily Max, but they are undeniable proof
0:25:49 > 0:25:52that bull elephants use this area on their wanderings.
0:26:08 > 0:26:10As Mike expands his thinking,
0:26:10 > 0:26:14he also expands his search.
0:26:14 > 0:26:17Eventually he gets his breakthrough.
0:26:26 > 0:26:27There's a faint signal.
0:26:29 > 0:26:31There he is!
0:26:34 > 0:26:37Yeah, that's definitely a signal!
0:26:37 > 0:26:40Woo-hoo, we found Max!
0:26:42 > 0:26:45That's excellent. Super, man!
0:26:45 > 0:26:51What we'll do is just drop in altitude and then download all this wonderful information.
0:26:51 > 0:26:57I've established a link with the collar, so it's downloading data now.
0:27:00 > 0:27:01Great, almost done.
0:27:07 > 0:27:10DOUBLE BLEEP And that's it, we have it.
0:27:10 > 0:27:13100% data acquisition. Super.
0:27:13 > 0:27:15Thanks, guys.
0:27:16 > 0:27:19Max's results are staggering.
0:27:19 > 0:27:24He has covered an astounding 13,500 square mile area,
0:27:24 > 0:27:28the largest home range ever recorded for an African elephant.
0:27:32 > 0:27:36Max is also moving beyond Botswana, crossing international boundaries,
0:27:36 > 0:27:38travelling a network of pathways
0:27:38 > 0:27:41from the rich woodlands of the north,
0:27:41 > 0:27:44to the barren extremes of the southern salt pans.
0:27:47 > 0:27:51At last, after years of guesswork, elephants are showing Mike
0:27:51 > 0:27:54exactly which routes they use from season to season.
0:27:54 > 0:27:56This was a direct communication
0:27:56 > 0:28:00between him and the elephants.
0:28:04 > 0:28:07Mike wants to know where Max is finding food and water
0:28:07 > 0:28:10on these driest fringes of the Kalahari.
0:28:10 > 0:28:15Retracing Max's journey, he begins to search for clues.
0:28:15 > 0:28:20There's some information satellite collars and satellite images can't give me,
0:28:20 > 0:28:23and I have to physically come out here and try and determine
0:28:23 > 0:28:27what's attracting elephants to these harsh and arid environments.
0:28:33 > 0:28:35There's a lot of elephant activity,
0:28:35 > 0:28:39clear signs and tracks of them moving across these little salt pans.
0:28:44 > 0:28:46Oh, my goodness.
0:28:46 > 0:28:49Right here, in the middle of this pan...
0:28:49 > 0:28:52This is how they're managing to survive, by digging for water.
0:28:52 > 0:28:55There's no surface water so they've had to dig for it.
0:29:04 > 0:29:07You can certainly drink it, it's not salty at all.
0:29:09 > 0:29:14It's a discovery that encourages Mike to look for other elephant activity,
0:29:14 > 0:29:18using some of the GPS points gathered from Max's wanderings.
0:29:18 > 0:29:21Most don't reveal anything significant,
0:29:21 > 0:29:25but one place Max has visited turns out to be very special indeed.
0:29:25 > 0:29:28I've been lucky to find a small water hole,
0:29:28 > 0:29:32and so this is going to greatly improve my chances
0:29:32 > 0:29:36of seeing the elephants, because I hope they come down and drink here.
0:29:36 > 0:29:40So I'm going to sit here and try and hide in this grass,
0:29:40 > 0:29:44and hopefully see some elephants this evening coming down to drink.
0:30:42 > 0:30:45This bull is probably 50 years old,
0:30:45 > 0:30:48with a full lifetime's knowledge of the Kalahari.
0:30:48 > 0:30:52That knowledge is critical to the survival of elephants here.
0:30:57 > 0:31:02It is wise old bulls like this that would have taught Max.
0:31:07 > 0:31:11If bulls are showing Mike just how far elephants can travel,
0:31:11 > 0:31:13what will Bontle's collar reveal?
0:31:18 > 0:31:21It is time to take her collar off and find out.
0:31:37 > 0:31:41The batteries in Bontle's collar are about to fail,
0:31:41 > 0:31:43so it's done its job.
0:31:44 > 0:31:47Go well, big girl.
0:31:47 > 0:31:52But it's also important to Mike that collars are removed once they're no longer necessary.
0:31:59 > 0:32:02You are free to go now.
0:32:02 > 0:32:04Thank you.
0:32:07 > 0:32:09Thanks, Larry.
0:32:13 > 0:32:17Now Mike must send the unit away for the data to be extracted
0:32:17 > 0:32:19and to find out exactly where she's been.
0:32:26 > 0:32:29This is a beautiful winter morning out in the bush.
0:32:29 > 0:32:34And it's a particularly exciting morning because I've just received the information.
0:32:34 > 0:32:36So the moment of truth has arrived.
0:32:36 > 0:32:40Bring it into my mapping programme.
0:32:41 > 0:32:42Oh, my goodness!
0:32:44 > 0:32:48Right where I'm sitting, she's been here.
0:32:48 > 0:32:53And you can see the paths she's actually using to migrate down here.
0:32:53 > 0:32:57Ten GPS coordinates a day - almost one every two hours.
0:32:57 > 0:33:01It's just fantastic. And a home range size -
0:33:01 > 0:33:0513,848 square kilometres.
0:33:07 > 0:33:10For Mike, this is a revelation.
0:33:10 > 0:33:16The average home-range size for an African elephant cow is 2,000 square miles.
0:33:16 > 0:33:20Yet Bontle had covered nearly five times that area.
0:33:20 > 0:33:25Like Max, Bontle's family needs to travel huge distances
0:33:25 > 0:33:29to survive in a place where food and water are so widely scattered.
0:33:31 > 0:33:33It's a clear indication
0:33:33 > 0:33:36of just how much wilderness these elephants actually need.
0:33:39 > 0:33:43But there is also something disturbing about her movement patterns.
0:33:43 > 0:33:46A clustering of waypoints up by the border
0:33:46 > 0:33:51shows that Bontle was repeatedly back-tracking across a small area,
0:33:51 > 0:33:54instead of venturing onward along the web of pathways.
0:33:54 > 0:33:58It suggests her movement is being blocked.
0:34:01 > 0:34:05This one of the region's veterinary cattle fences,
0:34:05 > 0:34:09put up years ago to prevent the spread of foot and mouth disease.
0:34:09 > 0:34:12In the north-west of the country,
0:34:12 > 0:34:15some of these fences run for hundreds of miles
0:34:15 > 0:34:18across some pristine elephant habitat.
0:34:18 > 0:34:24A fence like this is probably not a serious impediment to an elephant bull.
0:34:24 > 0:34:28But when we are talking about matriarchs with their calves,
0:34:28 > 0:34:32the old cows can probably step over the fence,
0:34:32 > 0:34:35but their calves certainly can't negotiate these fences.
0:34:38 > 0:34:41The matriarchs on their long migrations
0:34:41 > 0:34:45are stopped literally in their tracks.
0:34:50 > 0:34:55These are Bontle's movements, combined with those of other females Mike has collared.
0:34:55 > 0:34:58When a map of the fences is overlaid,
0:34:58 > 0:35:00one of the problems becomes clear.
0:35:00 > 0:35:04Some of Botswana's elephants are trapped.
0:35:06 > 0:35:09But there is another abnormal clustering of waypoints
0:35:09 > 0:35:12to the north-east of the fence, that Mike cannot easily explain.
0:35:14 > 0:35:17In this area, there are no fences,
0:35:17 > 0:35:23but what Mike finds there is just as dramatic and discouraging.
0:35:37 > 0:35:39Before sunrise every day,
0:35:39 > 0:35:41I watched thousands of elephants,
0:35:41 > 0:35:44mostly matriarchs and their families,
0:35:44 > 0:35:46running across these barren plains.
0:35:48 > 0:35:50Clearly they were highly stressed.
0:35:52 > 0:35:55These floodplains are an international boundary.
0:35:55 > 0:35:59And just beyond that there are many small farms,
0:35:59 > 0:36:02close enough for me to hear shouts and gunshots,
0:36:02 > 0:36:07as farmers drove the elephants back across the border to Botswana.
0:36:14 > 0:36:18Why were these elephants running back and forth night after night?
0:36:18 > 0:36:20Were they trying to raid crops?
0:36:21 > 0:36:25But why would they put themselves through so much stress?
0:36:27 > 0:36:30Mike realises then that Bontle and Max
0:36:30 > 0:36:34and the vast network of elephant pathways he's seen from the air,
0:36:34 > 0:36:35are giving him the answers.
0:36:39 > 0:36:44Desperate to follow an ancient migration path to distant food and water,
0:36:44 > 0:36:47these elephants are simply trying to get beyond the farms
0:36:47 > 0:36:51using an age-old route deeply ingrained in their memory,
0:36:51 > 0:36:55which is now blocked by expanding human settlement.
0:37:01 > 0:37:04This barrier is every bit as threatening to their survival
0:37:04 > 0:37:06as the fences.
0:37:14 > 0:37:16There are always consequences for elephants
0:37:16 > 0:37:18in such an unnatural situation.
0:37:20 > 0:37:24Their daily trek across and back is taking its toll.
0:37:24 > 0:37:25The females are stressed.
0:37:27 > 0:37:30Those with calves have little milk.
0:37:31 > 0:37:34And it is completely exhausting for young calves.
0:37:37 > 0:37:40Once the little ones stop moving,
0:37:40 > 0:37:41their fate is sealed.
0:37:44 > 0:37:47Some are just too weak to go on.
0:37:51 > 0:37:53I very rarely intervene.
0:37:53 > 0:37:58But on this occasion the crisis had clearly been caused by man.
0:38:10 > 0:38:14If I could just get this little elephant moving again,
0:38:14 > 0:38:19get him to catch up with his mum, who stood nervously waiting for him,
0:38:19 > 0:38:25perhaps he could make it to the shade and security of the Botswana side.
0:38:31 > 0:38:34Incidents like this are a stark reminder
0:38:34 > 0:38:37that the future of elephants is in our hands.
0:38:40 > 0:38:44Every year, human development blocks more migration routes.
0:38:47 > 0:38:52Botswana's elephants are now surrounded by fences and people.
0:38:54 > 0:38:58Elephants that came to Botswana looking for sanctuary
0:38:58 > 0:39:00are now stuck here,
0:39:00 > 0:39:02breeding fast,
0:39:02 > 0:39:04and with nowhere to go.
0:39:07 > 0:39:12There may not be an elephant problem now, but if they remain trapped,
0:39:12 > 0:39:15then soon there will be a crisis.
0:39:15 > 0:39:18Mike's findings don't just explain the problem,
0:39:18 > 0:39:21but also offer a solution.
0:39:21 > 0:39:26He believes that we can relieve the pressure of numbers, not by culling,
0:39:26 > 0:39:29but by giving elephants safe passage out of Botswana.
0:39:31 > 0:39:33Clearly it is too late to move people,
0:39:33 > 0:39:36but where Mike has identified clear migration routes,
0:39:36 > 0:39:40it may be possible to create elephant corridors,
0:39:40 > 0:39:43or gaps in the fences through which they can move.
0:39:43 > 0:39:46The placing of these gaps is very intuitive -
0:39:46 > 0:39:49you put them where their migration paths are, smack in the middle.
0:39:51 > 0:39:55We've got to be practical here. We don't have to decommission
0:39:55 > 0:39:59hundreds of kilometres of fencing, we just need to give them a corridor,
0:39:59 > 0:40:05to allow elephants to be released, we can release this bottleneck.
0:40:10 > 0:40:15Allowing them out of Botswana solves only one part of the problem.
0:40:15 > 0:40:18The question is - where could they safely go from here?
0:40:21 > 0:40:24Botswana's vast wilderness is largely surrounded by countries
0:40:24 > 0:40:27that are developing rapidly,
0:40:27 > 0:40:30filling up with villages and farms.
0:40:32 > 0:40:34But there is still one place that remains
0:40:34 > 0:40:37a perfect home for elephants, and which could provide sanctuary
0:40:37 > 0:40:40that Botswana's besieged elephants need.
0:40:43 > 0:40:48Angola, a country now at peace after a long civil war.
0:40:50 > 0:40:53Back in 1975, before the civil war,
0:40:53 > 0:40:58Angola had the largest elephant population in Africa.
0:40:58 > 0:41:02When Mike first flew over south-east Angola in 2001,
0:41:02 > 0:41:03at the end of the war,
0:41:03 > 0:41:07there were no elephants left in those extensive woodlands.
0:41:12 > 0:41:17Tragically, as many as 100,000 of Angola's elephants had been shot -
0:41:17 > 0:41:21for their ivory to help fund the war,
0:41:21 > 0:41:25or for their meat to feed their troops.
0:41:28 > 0:41:32Most of the elephants that weren't killed fled to the safety of Botswana.
0:41:35 > 0:41:41But the memory of the Angolan wilderness lives on in the minds of the older elephant refugees.
0:41:42 > 0:41:46There are signs that some of them are trying to return home.
0:41:50 > 0:41:56The great irony is that 30 years of war has actually preserved the Angolan wilderness,
0:41:56 > 0:42:00simply because it has been too dangerous for people to move back.
0:42:01 > 0:42:05Landmine fields like this are all over the place.
0:42:05 > 0:42:09There are an estimated 10 million unexploded landmines
0:42:09 > 0:42:11in this magnificent wilderness.
0:42:11 > 0:42:14I believe elephants can smell landmines,
0:42:14 > 0:42:20like rats and dogs that are used to help de-mine areas.
0:42:20 > 0:42:24Elephants have a very powerful sense of smell.
0:42:24 > 0:42:28So my hunch is, and early evidence suggests,
0:42:28 > 0:42:30that elephants can detect landmines.
0:42:35 > 0:42:41The matriarchs that used to roam freely in this part of Angola
0:42:41 > 0:42:44inherently will remember it.
0:42:44 > 0:42:50A lot of the pathways have lain dormant, and now the war has ended,
0:42:50 > 0:42:54there's a perfect opportunity for elephants to return back
0:42:54 > 0:42:56to south-east Angola, return home.
0:42:56 > 0:42:59Home is where the heart is.
0:43:04 > 0:43:07We need to safeguard these new migration corridors
0:43:07 > 0:43:10that elephants are using to return home to Angola,
0:43:10 > 0:43:13to help secure a future for elephants.
0:43:18 > 0:43:20Mike knows that given half a chance,
0:43:20 > 0:43:23more and more elephants will try to get back there.
0:43:24 > 0:43:28But it's crucial to protect their migration routes now,
0:43:28 > 0:43:32before rapid development in Angola blocks their route home.
0:43:39 > 0:43:44The Chobe River runs along one of Botswana's international boundaries.
0:43:46 > 0:43:47For the first time in decades,
0:43:47 > 0:43:51elephants from the Botswana side have begun to use the river
0:43:51 > 0:43:54as a crossing point again, heading for Angola.
0:44:01 > 0:44:05If Mike can continue to work with regional governments
0:44:05 > 0:44:08then he can help protect these corridors
0:44:08 > 0:44:12and ensure the elephants' safe passage.
0:44:12 > 0:44:15But to do that, Mike first needs to clearly identify
0:44:15 > 0:44:18where their old, cross-border migration routes go.
0:44:29 > 0:44:34What better way to map these highways than by asking an old bull elephant,
0:44:34 > 0:44:36who might remember Angola, to lead the way?
0:44:38 > 0:44:42Mike needs to collar a bull as close to the international border as possible.
0:44:42 > 0:44:46An elephant old enough to remember his ancestral homeland,
0:44:46 > 0:44:52and who will provide a GPS trail, as he journeys north into Angola.
0:44:52 > 0:44:55Yo! Look at that! That's so impressive!
0:44:55 > 0:44:59I've never seen so many large bulls in one bachelor group.
0:44:59 > 0:45:04We have to collar one in this group, the biggest bull, if we can find him.
0:45:05 > 0:45:09Hey, Larry, that big bull! The one with the big tusks!
0:45:17 > 0:45:21This huge bull is exactly what Mike is looking for.
0:45:21 > 0:45:24He's certain this old elephant would have lived in Angola,
0:45:24 > 0:45:26and will probably go back there.
0:45:51 > 0:45:53He's really impressive.
0:45:53 > 0:45:55Man!
0:45:58 > 0:46:00Super.
0:46:05 > 0:46:08How's his breathing, Larry? Good?
0:46:10 > 0:46:16'I really hoped this magnificent bull would become an ambassador
0:46:16 > 0:46:19'and lead the way back to Angola.'
0:46:19 > 0:46:23I think he's about 40 years old.
0:46:23 > 0:46:24Yeah, he's in his prime.
0:46:26 > 0:46:29Mike has collared more than 50 elephants
0:46:29 > 0:46:32in a massive trans-frontier area spanning five countries.
0:46:36 > 0:46:41He's unlocking the secrets of how these majestic animals move across this complex landscape.
0:46:48 > 0:46:50Let's call him Ntombo!
0:46:52 > 0:46:56The collaring of Ntombo is a new beginning.
0:46:58 > 0:47:03Mike's future challenge is to ensure that elephants have the freedom of Africa,
0:47:03 > 0:47:06that they can still wander as they did hundreds of years ago,
0:47:06 > 0:47:13and, most importantly, that elephants and people can learn to live peacefully together.
0:47:25 > 0:47:29I believe that elephants are a flagship species
0:47:29 > 0:47:32and if we can't save the African elephant,
0:47:32 > 0:47:36what hope is there for the rest of Africa's wildlife?
0:47:44 > 0:47:50The great bull Ntombo strode north into the wilderness of Angola,
0:47:50 > 0:47:52carrying his collar with him,
0:47:52 > 0:47:55following an ancient migration path.
0:47:58 > 0:48:01And now I dream that were he leads,
0:48:01 > 0:48:05a thousand elephants will follow.
0:48:24 > 0:48:27Subtitles by Red Bee Media Ltd
0:48:27 > 0:48:29E-mail subtitling@bbc.co.uk