CW HW NARRATOR RU ST VET NARRATOR Scientists are on the tail of one of nature’s best-kept secrets. Deep within Africa’s untamed wilderness, lions are doing the last thing we would ever have expected – they’re taking to the water. Dry savannah dominates much of Southern Africa. But sprawling over the northern reaches of Botswana, the terrain is startlingly different. Here in the midst of the Kalahari Desert is a surprising world of water, where life flourishes. This is the Okavango Delta. Every year around eleven billion cubic meters of water pour into the Okavango, most of which arrives as a huge flood in the middle of Winter. Over the space of a few weeks, the floodwaters replenish this vast watery paradise. The waters that flood the Okavango start out as rain falling on the mountains of Angola, to the north of Botswana. The water pours into the vast Okavango River, which bursts its banks as it flows South, fanning out into the massive flood plains that make up the Okavango Delta. Nowhere else on the planet is there a freshwater Delta of this size, landlocked far from the sea. The Okavango is a result of the unusual geology of this area. Around two million years ago, there was ancient freshwater lake here. Known as Lake Makgadikgadi, it was an enormous inland sea, so wide that it would have taken nearly a day to cross it by boat. Over the past twenty thousand years, since the end of the last ice age, Lake Makgadikgadi gradually dried up. As water levels dropped, a vast network of small rivers and islands emerged. And so the Okavango we recognise today was formed. Such a remarkable Kingdom needs a ruler. Enter the lion. Lions have a reputation for taking life in their stride. Arguably the most adaptable of all the big cats, they’ve dominated places as diverse as the harshest desert and the most lush woodland. But the Okavango is so extreme, that to find lions thriving here is a real surprise. Making it here has involved a dramatic sacrifice: the lions have had to take the plunge into a totally new way of life. We expect lions, like most cats, to detest getting wet. But during the wet season these lions live a semi-aquatic life that sees them hunting prey as they move from island to island. To see a lion swimming confidently and moving through the water with powerful strokes is an extra-ordinary sight. Proud and strong, the Okavango lions don’t like to swim but they are resilient and determined to survive. The Delta might be tough but these lions are tougher. Some of the swimming lions are unwittingly taking part in a science project. Lionesses from different prides wear collars containing tracking devices. Risking the treacherous swamps, these scientists are trying to understand how lions are managing to live here. Today’s mission is to fit a new collar. This means getting close enough to dart one of the lionesses. Taking care with the lion’s health, the vet has only given her just enough knock-out drug to allow them to handle her. VET I suspect she’s not going to do anything CW Rather be safe than sorry NARRATOR Running the swimming lion project is Hanlie Winterbach alongside her husband and fellow ecologist Christiaan. The Winterbachs have started using a new method for finding the lions, called geo-positioning system or GPS, which is more hi-tech than traditional radio-tracking. CW A normal radio collar just has a VHF radio basically built into it that transmits a signal that we can pick up to find the lion. The GPS collar has that plus it has a built in GPS that’s using the satellites to collect position data for us where this lion has moved. Then every month we download that data. So the lion basically walks around collecting the data for us. NARRATOR The rest of the pride has retreated to a safe distance, where they can still keep an eye on their missing female. VET I’m just going to push her up and then we’ll roll her over, oh OK, you’re going to do it that way, OK. NARRATOR Although in this part of the Okavango the lions rarely encounter people, over the years they’ve become accustomed to periodic visits from the science team. Two more biologists have recently joined the project: Ruth Kaminitzer and her partner Steve Ross. HW – Steve and Ruth joined us in June. Steve is going to do his PHD on a project that we are going to do as a comparative study between the lions in the delta and the lions in the central Kalahari. Ruth is doing all our writing of papers and articles and she also does a lot of the data analysis. At his stage we share all the work between the five of us including Albert which makes it really nice and we’re an excellent team. ST – Usually I go out and we see the lions from around twenty metres away or some thing, but now we’re actually right next to her it’s quite a lot different. The thing that really gets to you is the actual size of her neck, her head and everything and her paws. You can see her paws, Hanlie’s just touching her paws there it’s quite amazing. VET Alright, as I finish the injection… NARRATOR Vet Rob Jackson gives the signal for everyone to pull out. An injection that reverses the effects of the tranquilliser drug will bring the lioness round within a few minutes. They carefully move away to leave her to wake up and wander back to her pride. Job done, the team heads back to base. For them home is a small camp nestled among the Marula trees, right in the heart of swimming lion country. For the Winterbachs, understanding the Okavango lions is now their life’s work. They gave up everything to come here from South Africa, five years ago, to set up a new life at Lion Camp. CW This is part of our study area. Camp is situated in an area where we have seasonal flooding. If you go much wetter than that it becomes a big problem and if it’s drier than that and won’t get the data about the lions in the water. These dots for this particular pride covers about two years and that we collected with normal radio tracking. What the GPS collars making possible is to look at the movement of lions in much greater intensity than previously possible. Here you can see all the places that this particular lioness visited in twenty-four hours. She crossed a major flood plain system with a big deep channel, crossed another flood-plain system then went into a big island, walked around on the island and then bedded down there. NARRATOR To get accurate information on the lions, the team lives among them for eleven months of the year. To do this they’ve had to create a complete research station in the middle of the bush. CW Over the five years we’ve developed camp a little bit and that makes life a lot easier living in a remote area if you do have some bits and pieces of civilisation to help you. NARRATOR Every day and most nights are spent out in the field with the lions, a job made all the more difficult by the floods. The team knows they’ve a difficult task ahead, to monitor the lions this winter. Four different prides share the area around Lion Camp. It’s these lions that the Winterbachs are basing their study on. In total there are around eighty lions in the whole project. This pride has been given the name Mochaba, which is the local name for the sycamore tree. This morning they’ve woken up to find the floodwater is advancing rapidly towards them. Strangely, no matter how many years they’ve had to deal with the water, some cats just never lose their instinctive aversion to it. Others are braver, at least when it’s still possible to find a shallow place to cross. The Mochaba pride knows that the arrival of the winter floodwater means having to think a lot harder about how to get around. From the air, Christiaan can get a quick and reliable fix on where all the prides are, something that takes the team days to do on the ground. CW Why we are interested in these lions if to find out how they cope with all this water and how the water effects the way the lions live in this very different environment from what we typically assume to be African plains. NARRATOR There are around one and a half thousand lions down there, ranking the Delta population fourth largest in the world. CW The Okavango Delta is a real lion oasis here in the middle of the Kalahari desert. Eighty percent of the lions living in Northern Botswana are living within this delta. NARRATOR The reason the lions stay here is simple : food. There is more prey here in the Delta than in the surrounding desert. In the Okavango if you’ve got hooves you’re toast! Like all big cats, the Delta lions are natural born killers. Despite the riches provided by their watery home, the Delta is as much the lion’s enemy as its friend. The same water that provides food for the lions also presents a massive hurdle to their survival. This winter, like every winter, the huge influx of water that gushed into the Okavango has brought with it a new set of challenges. HW The delta is not typical savannah ecosystem. You have once a year this massive flood of water coming down, but each year it’s different. This year some flood plains will have water, next year those same flood plains will be dry. The flood levels are always different and the lions have to adapt to this environment quite drastically the lions are actually battling quite hard to be able to hunt effectively at this stage. NARRATOR The problem is predicting where dinner is hiding in this massive network of islands. The lions though have come up with is a clever and unique solution: neighbouring prides have learned to share hunting grounds. HW The feature that the lions share such big parts of their ranges with each other we suspect is very unique to the delta ecosystem and this is a behavioural adaptation that the lions had to do to cope with this mass of water that is coming down each year during flooding times. NARRATOR Co-operation seems to improve the odds of finding food. A change in behaviour like this is exactly what we would expect. Lions, like all meat-eating mammals, have to be good at adapting to local conditions. But adaptability doesn’t always equal survival, especially when your home is as unpredictable as the Okavango Delta. For one lioness there’s no doubt that living here is a constant challenge. Sadu is a ten year old female. She lives only with her two cubs, since she was forced to go it alone after some aggressive males took over her pride. Living without the protection of a big pride has made Sadu change her survival tactics. She and her cubs must cover huge distances in the search for food, which makes tracking them all the more difficult for Steve and Ruth. ST Yeah, the problem is that Sadu’s signal is somewhere over there. Unfortunately it’s right across the flood plain where Sadu usually is. RU Yeah, sometimes we get really close, but have to give up in the end ‘cos there’s water all around. It’s really frustrating when you know she’s on this tiny, tiny little island in the middle of this floodplain, but you can’t see her ‘cos she’s gone into the thick brush and she’s sleeping there, so you just wait on the edge until she decides to get up and leave. ST It doesn’t pay to go straight through the floodplain, it often pays to go a long way around so you don’t get stuck ‘cos you’re gonna waste a lot of time getting stuck. There’s also the problem of getting to her and then getting stuck, we’ve done that with Sadu, we’ve got stuck right next to her and then had to try to get ourselves out right next to the lions which isn’t a very comfortable experience as you can imagine. RU So far she’s been very understanding, but there’s always that risk. NARRATOR They’ll have to persevere. It’s important they get close enough to check the condition of the lions to see how well they are coping this winter. Even avoiding the deepest part of the floodplain still means they have to drive through water over a metre deep. Sadu seems to like it out here. As far as she’s concerned, the wetter the better. NARRATOR It’s on these almost impenetrable islands, that abundant prey animals like lechwe thrive, alongside other antelope like waterbuck and reedbuck. The swamp also supports a huge number of birds like the saddle billed stork and great white pelican. A fish eagle searches for its next meal from the air. Given the option, most lions will stick to hunting on land. But Sadu is different. The pressure to feed her two growing cubs is great and, against all odds, she’s become a supreme hunter in the water. Roan antelope rarely move far from water. They love the lush wetlands of the Okavango, tending to seek cover from the wooded islands. But Sadu is one step ahead. She has a fully-grown roan in her sights. There’s nothing the other antelope can do now except try and keep themselves out of trouble. Sadu grips the antelope’s face in an attempt to suffocate it. Tombo, the male cub, helps to pin it down. The female cub, Tembe, has made a bonus kill: a roan calf. Roan are highly aggressive with horns that can easily maim an inexperienced lion. The struggle is intense. Tembe must have managed to corner this young roan in the confusion of the fight. This may well be her first kill in the water. Sadu has taught her well. Keen not to miss out on her share of the big kill, Tembe returns from stashing her own trophy in a safe place. An adult roan like this provides around a hundred and twenty kilograms of meat. This will keep the trio fed for two days. Once they’ve quickly wolfed down enough to take the edge off their hunger, lions will hide their kill from scavengers. Having killed in the water, Sadu has to drag a waterlogged animal that weighs more than twice as much as she does. Sadu’s exhausted, cold and wet through. Seeing lions battling to hunt, belly-deep in water is nothing less than awe-inspiring. Lions have existed here for thousands of years. At some point in the past one lion, perhaps braver than the others, or driven by hunger, ventured into the water. It wouldn’t have taken long for other lions to follow suit. The ability to adapt was already in the lion’s genetic blueprint. Tackling life in a swamp by learning new behaviours, like swimming and hunting in the water, could have developed within just a few generations. CW When we started our project we knew the lions had to swim, but we didn’t know to what extent the water was influencing their lives. When we found that up to seventy percent of their home range can be covered by seasonal flood waters we realised the size of the problem they are facing. With the help of the GPS we have built up a very accurate picture of how they move in this environment. Basically every day of their lives these lions have to cope with the challenges posed by the water. NARRATOR The Central pride has killed a buffalo. While the floods are high, every kill is a bonus. This is the biggest and most established pride in the area. Strength in numbers means that when they do kill the prize is likely to be a big one. A young female paws at the ground near the carcass. This peculiar behaviour may be leftover from a time in the lion’s early history when they used to bury food in the ground. Although lions don’t do this anymore, primitive behaviours like this may still be hard-wired into their makeup. Basic instincts are a big asset in the wild. Vultures flock around the lion kill and their partners in crime - the hyenas - are never far behind. Although they are perhaps the best adapted carnivores to life in the watery Delta, hyenas are never shy about trying to cash in on someone else’s hard work. One of the older lionesses sees off the intruders. This time the hyenas will have to go hungry. To make the most of every opportunity, the Okavango lions have evolved to run their affairs with almost military planning. In large prides several females will work together, using a pincer movement to home in on their victims. They’re also perfectly built for the job. Padded feet help to muffle their footsteps. Stealth combined with good camouflage helps to get within striking distance. But even armed with this arsenal of weapons, the average lion needs to hunt five times to make just one kill. And how do these narrow odds translate in a place where the hunting ground is flooded and where more often than not there’s no choice but to swim for your supper? CW In most parts of Africa they never need to swim, but here in the Okavango Delta they don’t have the option they have to swim to get from place to place. NARRATOR Luckily lions do have a muscular physique and a natural ability to co-ordinate their bodies in water. CW Lions are built very similarly to Tigers and similar to Tigers they are very capable swimmers. NARRATOR But the landscape here is very different from the swamps found in Asia where tigers are known to swim. The Okavango is characterised by wide, exposed flood plains. Hunting in this kind of terrain leaves the lions at a disadvantage because their prey can easily see and hear them coming. Normally an injured animal like this lechwe would be easy pickings. But the water greatly stacks the odds against the lions. During the flood, the one in five average of making a successful kill is rarely achieved. The water also has a big impact on the lions themselves. Water takes heat away from the body twenty-five times faster than air and swimming during winter puts a massive strain on the lions and saps their energy. CW We’ve been seeing things that we think may be some adaptations to this water environment. Lions here have longer and more fluffy coats than lions in the drier neighbouring areas. NARRATOR It’s possible that these lions have grown fluffier coats for insulation, since thicker fur traps more warm air next to the skin. CW It will be interesting to approach this more scientifically to see if this is an actual adaptation, but even without that we are very sure that our lions have adapted to this unique water environment. NARRATOR The biggest changes aren’t to the lions’ physiology but to their behaviour. The swimming lions have learned how to use the floods to trap prey on the islands. The Mochaba pride moves around together so that if they find food on the next island, they can quickly spring into hunting mode. This female is injured and even she will struggle to cross the water and keep up. Without the protection of the rest of the pride she could easily be killed by hyenas or at the very least starve to death, unable to hunt effectively on her own. For the Winterbachs getting a head-count is always reassuring. From their observations they know the lions feel vulnerable in the water. Snarling may be a reaction to the shock of the cold or a sign that they are aware there could be hidden dangers. Christiaan and Hanlie have been monitoring this pride since the lions were just a few months old. HW We once saw the Muchaba pride when we were following them, the mothers walking through the floodplain and the tiny little cubs saw this huge expanse of water and they just closed their eyes almost and ran and swam through it as fast as they possibly could and ended up on the island where they could shake themselves out and wait for their mothers to slowly walk through. NARRATOR The youngest cats have now seen three winters come and go. HW All of these lions have to cope with the water during the winter times. I can imagine it gets quite unpleasant for these lions because they’ve got to swim through the water when it’s coldest here, especially at night when it’s sometimes freezing cold and if they hunt they’ve got to cross the water. ST OK, that’s far enough Ruth; do you want to pass up the equipment? NARRATOR Steve and Ruth have finally found a way to cut through the floods to get close to Sadu, who is resting on a big island. Sadu is trying to sleep but Tembe and Tombo are ever playful. Even though they are two years old, they still pester Sadu, pretending to suckle. Behaviour like this keeps them closely bonded with their mother - vital to giving them a good start in life. ST Sadu unfortunately gave birth to cubs by herself and that reduces the chances they’ll survive, however she’s overcome all these risks and actually the cubs have pulled through. The males almost always leave by the time they are three or four years old, so while Tembe is likely to stay with her mother Tombo’s likely to leave. They usually leave when other males come in and chase these youngsters away. NARRATOR Every day they face the threat of intruders disrupting the family. So far though they’ve been lucky and Sadu has been able to concentrate fully on raising Tembe and Tombo. RU For me it’s always interesting to see the two youngsters with her because so much they follow her every movement. If she moves to the shade they go, hmm, I’m gonna move to the shade with Mum. You don’t see any of that dissension you seen in humans between kids and their mother they just seem to copy her every move. Now the young female cub is so relaxed that she’s actually wandered over to the car to come check us out and you just see Sadu sitting there thinking yeah, OK, no problem. Then the female cub goes off to Tombo her brother and tells him all about what she saw ‘cos he doesn’t do that he just lies there, kinda cool. NARRATOR Lions are the only big cats that form prides and enjoy group life. Nuzzling and licking is a way of exchanging scent and binding families together. Learning starts within minutes of birth. Play forms a crucial part of the learning programme building muscular strength and physical coordination for the hunt. And, as we’ve seen, here in the Delta there’s an even more critical aspect to learning – knowing how to cope with your home being flooded year on year. In this incredible and unique display of behaviour from Sadu’s cubs, we’re seeing for the first time just how comfortable these lions have become in the water: comfortable enough even to play in it. Being this relaxed at such a young age will stand Tembe and Tombo in good stead for becoming successful hunters in the water. Only twenty thousand years ago, a mere blink of the eye in terms of the Earth’s history - this whole area was permanently underwater. Currently the majority of lions only have to cope with their home being flooded for a few months of each year. This is bad enough. If it were ever to return to a state of permanent deep flood, life for the Okavango lions would take a dramatic turn for the worse. Unable to adapt fully to an aquatic way of life, the lions would have to flee the Delta and be forced into conflict with lions in neighbouring areas. As the flood season draws to an end for another year, the Mochaba pride is showing the signs of fatigue. But still they press on in search of food. All across the Delta, lions are working hard to stay alive in spite of the floods. To really thrive in the Okavango, you need to make the water work for you. Lechwe have evolved to be more comfortable in the water than out of it. Staying in the water, away from the edge, is a good tactic for evading your oppressors. Most of the time. Like the lechwe, Sadu has also learned how to turn the water to her advantage. Perhaps being on her own with two cubs to raise has turned her into a different kind of hunter. For the other lions making kills in the water still seems to be opportunistic. But Sadu is a class apart. Her kills seem to be almost pre-meditated. This time her victims are a female lechwe and its calf. Sadu follows them through the water. She’s trained herself to swim almost silently, vital if she’s going to stand a chance of getting close enough to guarantee a kill. She knows that once she commits to the sprint she’ll be massively handicapped. In water lechwe are much faster than she is. To close the gap she needs to play a patient game. On the other side of the study area, close to Lion Camp, the Winterbachs are with the Central Pride. Two of the lionesses gave birth to cubs a few weeks ago. With any luck the youngsters will be swimming off this island with their mothers in a few weeks time. But in the Okavango there are no guarantees. HW I think that the waters biggest effect is on the survival rate of the cubs. If we think that it’s very difficult for us we can imagine what it’s like for these lions having to swim thought these flood plains, hunt and to raise their cubs and just to live in this wetland environment. When the females are breeding and they give birth to cubs during the times of high floods the lioness has to spend more time looking for prey than she would when the floods are not here. We’ve had lionesses that had to spend so much time away from the cubs to get food that they died. They’re just so vulnerable if the lionesses leave them on an island. NARRATOR As Christiaan and Hanlie have learned, taking the rough with the smooth is all part of living in this remarkable place. HW To live out here is amazing. It’s really beautiful. Sometimes it’s frustrating, but even with all the frustrations that we might have here we wouldn’t want to trade living here with living anywhere else in the world. NARRATOR Sadu will continue to teach her cubs how to survive in the water and out of it. By being so finely tuned to life here and such an excellent mother to Tembe and Tombo, Sadu has ensured that their chances of becoming successful in the face of adversity are strong. These lions and others like them in the Okavango have dispelled the myth that lions and water do not mix and once again have proved that, against all odds, the King of the Beasts will survive.