The World's Most Unlikely Animal Relationships _ Animal Odd Couples _ Real Wild

We're fascinated by animals that behave in ways we would never expect. Millions of us watch clips of different species that normally wouldn't come together showing what looks like friendship, affection and even love towards each other. Kate took one look at her. Thank you. I'll take over now. Stop it. That just melts your heart doesn't it? It did. But what lies at the heart of these behaviours? Can science explain why these unusual partnerships take place? I'm Liz Bonnen and I'm going on a worldwide journey of discovery to find out why animals of different species make friends with each other. Why a cat would adopt ducklings. I was blown away by what I was seeing. I just couldn't believe it. If an orangutan could really keep a dog as a pet. Or if two animals of different species could even fall in love. I'm on a mission to find the world's cutest and weirdest animal friends. This jaguar and Jack Russell are inseparable. When staff tried to move the jaguar to a bigger enclosure of its own as it grew up they were having none of it. They both cried and whined incessantly until they were finally reunited. And this does beg the question, how on earth does this work? Cats and dogs don't normally get along. But here in this wildlife park in South Africa, Bullet the Jack Russell is best mates with a predatory jaguar named Jag who could easily have him for dinner. But instead, Bullet and Jag spend as much time as they can together in this enclosure. They eat and sleep together and are always playing together. So what's going on? For a long time we've thought that most animals of different species have evolved to stick to their own kind and to generally not get along. But in recent years, the internet has been changing all that. Videos getting hits in their millions are showing different species interacting in ways that scientists didn't think were possible. So how can we explain these relationships? And what can they teach us about how the animal kingdom really works? To find some answers, I'm going to start by meeting a variety of animal odd couples that seem to be the best of friends. And I'm beginning my weird and wonderful journey in Atlanta, Georgia, in the southeast of America, because I've heard about an incredible example of animal friendship between the most unlikely of species. They live here in this refuge, with over a thousand other injured, orphaned and abandoned animals. So this is Baloo, an American black bear. He's 12 years old and he's been at this wildlife sanctuary here in Atlanta ever since he was a little cub. And all through his life, even into adulthood, he's been keeping company with a couple of animals, well, you just wouldn't expect. And there's one of them now. I've never seen a fully grown bear and tiger in the same enclosure before. Shere Khan is a Bengal tiger who's also around 12 years old. Asian black bears and tigers do share the same territory in the Far East, but when they meet, one of them ends up badly injured or killed. And so to see these two guys, they're around 12 years old, showing so much affection for each other is pretty amazing. The third member of this unlikely friendship is a lion called Leo. The bear's the boss, and then Leo the lion falls in second, and then Shere Khan's a little, you know, he's a little wild child. When they're sleeping in the clubhouse, all three of them, they pile in together. They just know each other and they love each other. Jama Hedgecoth is the founder of this sanctuary, and she's looked after the three of them since they were just a couple of months old. Kept illegally as pets, they were confiscated by the authorities and brought to her wildlife sanctuary. They had been in a dark basement, and they were all kept together. And then the tiger and the lion's noses were busted up, and they're scarred to this day. What absolutely fascinates me is the fact that these are grown predators in their own right, who are displaying so much affection for each other. What do you think is going on here? Well, they're truly a family. They've never been separated. We tried twice when they first came in, and they wouldn't eat. They cried all day. So over about eight or nine hours, I said, oh, well, they're just babies. Let's put them back together. Would you describe these three as friends? Very close friends. I wished I had a friend as close as they are. It's difficult not to think that they are friends, that they care for each other when you see how they behave with each other. Except for that. Oh, yeah. You know, they get to go on. Is this play going on? Oh, yeah, this is play. Shere Khan is pushing Baloo, and Baloo is ready to go to sleep. And Shere Khan does this all the time. He does it to Leo, too. I'm loving Shere Khan's personality. Yeah, I mean, Shere Khan is the one that... Look at that, look at that. And he'll have to back down. It's nice to have seen that kind of behavior, too. Yes, yes. For some reason, it just makes me happy that they have those kind of barnies. They have to, because they're not sedated. They're real. That is who they are. I'm amazed by what I've seen. So to get a scientific view, I've asked Clive Wynn, a psychology professor who studies animal behavior, to have a look at this unlikely animal friendship. What would you make of this situation, Clive? It's beautiful. I really love it. I think it's marvelous to see animals that started out such difficult early lives being given such a beautiful home, being given true sanctuary. I think it's a wonderful thing to see. And what do you think about the nature of their relationship, you know, how they behave together, and, dare I say, how they might feel about each other? Yeah, well, so I've been watching them play for a little while now, watching them interact with each other, and I've been thinking about, well, what's the best way to capture what I see? There are elements of rivalry. There is a pecking order here, and I saw the tiger testing the bear a little bit. And you get that with brothers. So I would say it's a brotherhood. Do you think one of the big factors involved in this relationship, especially in the early years, was a certain type of bond to relieve the stress they were experiencing? Yeah, absolutely. Absolutely. There's good research. I mean, obviously not on lions, tigers and bears, but animals at all stages of life, including ourselves, get buffering of stress. It reduces your stress to have a companion with you, a friendly companion with you. And one feels it oneself, right, in your daily life. If you have to go and do something stressful, it's much nicer if you can bring a buddy along. So it seems that the friendship these three found in each other helped them through the tough early days. And over time, it developed into a wonderfully close lifelong bond. The need to find a friend no matter who they are is clearly a very strong instinct. You can see it in animals that have been brought together by captivity, particularly if they're very young. Just like this baby chimpanzee who's found a companion in a puma cub. And there's one factor that always seems to be involved in their everyday lives. Play. So why is that? Is play a crucial part of what creates these cross-species bonds? To find out, I've travelled to South Africa, just outside the coastal town of Port Elizabeth, to meet a couple of animal friends who just want to play all the time. This is Hugo the bulldog. And his friend, Igor, the lion cub. Look at that. Hand raised in this safari park, they've formed a very close bond, and their favourite activity is a bit of rough and tumble. Classic. You are a happy dog. To help me understand how play works between different species, I talked to animal behaviour expert Dr Linda Sharp from the University of Stellenbosch here in South Africa. Play signals are fairly universal in that they tend to be all things like rolling on your back. It's making yourself vulnerable. They're very reversed of aggression. So even if it's two completely different species, they'll be able to read each other's body language. Yeah, if someone is rolling on their backs and wiggling, they're not about to attack you. I mean, you can see that. And so all these species tend to have the play signals that initiate play, and they tend to be the absolute reverse of how they behave when they're being aggressive. This might help to explain an example of play between two very different species that became an internet sensation with over 11 million hits. In Canada, polar bears, one of the most fearsome predators on Earth, have been witnessed playing together with huskies in the most surprisingly affectionate way. The huskies are tethered at their home base in Manitoba, and these wild polar bears are waiting for the winter ice to return to this stretch of coastline. The huskies should, by all accounts, be an easy snack, but the polar bears are clearly not hungry, which frees them up to play. But that doesn't really explain why they would choose to do this. So why does play seem so vitally important, even when it's with a different species? The unusual thing about play is that the behaviours that are incorporated into play are all flight and fight behaviours. They're all excitement, they're things that really hype you up. And so one theory is that play, you're activating, you're doing this exciting activity that's just a little bit dangerous. You're pretending there's a predator after you, or you're being overcome by this other animal who's fighting you, and so there's this little fission of excitement and stress. It's these little peaks of mild stress in safe circumstances that Linda believes help prepare animals for the challenges of life. And playing with a different species adds to the thrill of the unknown. When a young animal is stressed, it alters its sensitivity to stress. So next time it suffers a trauma, it doesn't get as stressed. It doesn't respond so badly, it recovers quicker, it's not traumatised as much. Especially if it's a different species that normally you'd run from, but you're playing with, you might get an added extra bit of stress that you then get sort of habituated to, and that helps you in future life. So Linda believes that these polar bears and huskies are getting more of a thrill from playing together than they might do playing with their own species. And this potentially helps their bodies to cope with more dangerous situations. Stress in small doses is clearly beneficial. But too much can be dangerous. I've travelled across South Africa to a secret location to meet an animal that's so reliant on its friends, it will die without them. This is a cross-species friendship that's not only saving lives, it's helping to save an entire species. Rhinos in Africa are in crisis. They're being slaughtered at an alarming rate for their horns because they're prized by the Asian medicine trade, despite the fact that they have absolutely no medicinal value whatsoever. Now in South Africa, last year alone, 688 rhino were killed. And that's tragic enough in itself, but it gets worse because it's led to an unprecedented number of orphaned, traumatised calves like these two. Now if they're very, very lucky, they get to come to a place like this. Heavily guarded, it's a relative safe haven where rhinos are brought to help reduce the risk of poaching. But they've also discovered that cross-species relationships can help save the rhino orphans they receive. This is all because young rhinos are surprisingly fragile. The closest rhino relationship is the one between a calf and its mother. It's totally dependent on her for up to two years, so an orphaned calf needs a lot of care. Not only that, but they just don't do well if left alone. Dr Yana Pretorius is a specialist wildlife vet who looks after the little ones. Yana, how old are these calves? Ella is about 15 months. Benjamin is about seven months. And are they both orphaned from poaching? Yes, they are, unfortunately. So you pair them together, and this is everything they need to have a good chance of survival and then ultimately for re-release into the wild, right? Yes, preferably when they are orphaned, they need to have a companion because the stress of being alone will kill them. Large doses of the stress hormone cortisol can be a serious problem for rhinos. The gland that produces cortisol produces so much cortisol it can't produce anymore, so the body can't cope with the stress anymore. Together with the stomach ulcers, then they normally do end up dying. So if the rhino calf can't be paired with another orphaned calf, then is it best for a human to take care of it, or is that a bad idea? Like, what can you do? It is in a way a bad idea because humans can't stay with them all the time. And the moment, for example, a human has to go away or is sick and you have to use, or somebody else needs to look after him, just that stress of somebody else being there is already quite bad. Whereas with animals, it's slightly different. You can always have the animal with them, or maybe more than one. When you talk about putting them with other animals, what animals do you put them with and why? The best would be something like a sheep or a foal because they also graze and you want the rhinos to learn to graze from a young age. If they're with humans and, for example, dogs, they end up not wanting to graze. And we have seen that, where they actually will eat dog food but won't eat grass. So you put them with a sheep, and how close does this bond become? And what is it about that bond that makes these animals de-stress and give them a better chance of survival? It's purely the companionship of not being alone. When they're alone, they're uncertain, they can't see well. They're very insecure animals, the calves. You wouldn't think of a rhino as being timid. Especially the white rhino, they're very timid. I find rhino bums amazing, they're just so fat and gorgeous, with a little dinky tail. They're amazing, aren't they? With the careful introduction of a close companion, precious rhino lives are being saved. But could such a deep bond ever develop between different species without our encouragement? I've travelled to the west coast of Canada, just outside the town of Courtney on Vancouver Island, because I've heard about the most endearing relationship between two different species that came about purely of their own choice. Many companionships between different species develop because of captivity. Circumstances essentially bringing animals together who normally wouldn't keep each other company. But here on this tiny little corner of Vancouver Island, two animals have been hanging out together for years and they're both free to come and go as they please. Pippin is a wild black-tailed deer who's formed an incredibly close bond with Kate, the Great Dane that lives in this house. Pippin leads a wild existence, coming and going as she pleases. So I've been told the only way she might approach the house while I'm around is if I hide inside. Five years ago, Kate's owner, Isabel Springett, discovered Pippin in the woods when she was just a tiny newborn form. She left her there, hoping her mother would come back and find her, but it didn't quite work out that way. The next day I started hearing the crying. And that went on for three days. So that was it. I thought, this is crazy, I'm taking her in. And the only reason I put her on the dog's bed is because it was the only spot to put her. And Kate took one look at her, and that was it. It was, thank you, I'll take over now. Oh, stop it. That just melts your heart, doesn't it? It did, yeah. This is a film Isabel took of those early days together. There is this maternal behaviour going on with Kate? Yeah, definitely. She never had puppies. When it comes to little things, she's maternal. But did Kate ever suckle Pippin? No, she had nothing to suckle with. But she would try. Really? Oh, boy, did she try. Did Pippin try to suckle? Kate would stand there and she'd be bunting and bunting. And Kate was so patient, she never told her off. Really? No, and we'd be getting the bottle ready and she would be bunting and sucking on nothing, you know. Poor Kate used to feel sorry for her. Poor Kate was like, it's OK, I'm just going to take it. She'd just hump her back and stand there. And so at what point did Pippin begin to sort of get back to the wilds, would you say? Two weeks old. Yeah. Two weeks old? Two weeks old, yeah. At two weeks, she insisted on sleeping in the woods on her own at night. And we thought, well, if something eats her, that's just the way it's going to go. We can't interfere. Would Kate ever follow her into the woods at night? Oh, yeah, yeah. Kate would follow her. Sometimes she'd watch her go, like... She's gone. But then, she never left Kate, did she? I mean, she didn't disappear forever. No, no, she'd come back every day, every day. Every single day? Every single day. So how long did this maternal behaviour carry on? Probably till Pipp was about six months old. And then it sort of turned into a friendship, playtime, buddy thing. The older Pipp got, the more they would play like friends. It's nothing like I've ever seen before. It's not like a dog and a dog playing. It wasn't like a deer and a deer playing. Kate toned down the aggression a little bit with the play. She would be more aggressive playing with another dog, but with Pippin, she was more careful. And Pippin seemed to be a little more rough than I've seen a deer be. So it was two different species compromising. They would smack into each other and run and leap and do their neck twirls and lick and... Oh, it was really funny to watch. How old are these two now? How long have they known each other? Five years, yeah. And I think Pipp's had one, two, three, four, seven fawns now. Pippin spends the majority of her time with the wild herd, but she returns to the area surrounding the house each year to give birth to her fawns. You know, the beginning of their relationship was a maternal, nurturing sort of relationship. And now it's like old friends. What makes you think that? The way they greet each other. They don't greet each other like, hey, you know, they greet each other like you would a really good old friend that you see quite often and you just, how you doing? And just hang out. You don't even have to talk. Do they play still or how do they hang out? They don't play, they're too mature for that now. Pipp's a mum, she doesn't play. But no, all they do now is they'll walk up, maybe do a little nuzzle. Kate will lick, Pipp loves to lick Kate. And they just hang for a few minutes and then they'll flop down in the shade together and just hang. And how long will Pippin stay with Kate at any one time? She can be here for three or four hours sometimes. She'll come right into here and sleep on one of the dog beds with her sometimes. Even if we were gone for five years and came back, they would greet each other as old friends and it would be the same, yeah. This is a lifelong bond formed from a maternal instinct that developed and was cemented by years of playing and spending time together. The relationship between Kate and Pippin is remarkable. Two animals seeking each other out to spend time together without the constraints that are often made by man. And to me, that makes this animal friendship far more compelling than in captive situations. So far, I've met many different animal friends that have found each other through their unusual circumstances, be they in captivity or in the wild. And it's clear how important play and close interactions can be for maintaining those bonds and even for keeping an animal alive. But hearing how Kate looked after Pippin when she was a tiny fawn introduces another important reason for animals of different species to come together, the mothering instinct. On the next step of my journey, I'm going to investigate stories of misplaced mothering that defy belief. Incidents of predators ignoring their hunting instincts and instead caring for young animals that should be their prey. But first, I'm going to the south of the USA to Mountain Home, Arkansas and a wildlife refuge that's home to a remarkable supermum. This refuge takes on many abandoned animals in need and it's run by a devoted carer named Janice. But it's her capybara, Cheesecake, who's the star of the show. She may be the world's largest species of rodent, but she's also an excellent foster mum to a litter of puppies. So how did this scenario arrive, Janice? I mean, this capybara is surrounded by I don't know how many puppies. I've lost count. Yes, it's just one day I had a litter of orphan puppies that were ready to move out of the house and this was the most secure pen for a little puppy. And I knew she was social with other animals and she took right to it and she's had every litter since. So how many litters has she had? Well, this year alone she's on number four and there's another one coming up soon. So you get, unfortunately, a lot of puppies given to you from abandoned litters. I rescue a lot of pregnant mamas or mamas that just have given birth that are in dire straits and nowhere to go and it's one of the specialties I do for special needs animals. So it's an unfortunate situation, but when you say that the capybara mothers these pups, what do you mean? She sleeps with them, she eats with them, they'll play with her, they'll broom her and she seems to enjoy it. I think she just has kind of that aura around her that makes them feel safe and secure. Cheesecake has never had her own young. But being a capybara, she knows exactly what to do with this lot. In the wild, capybara help to look after each other's young, sharing the parenting duties. And what she's demonstrating is just how powerful that mothering instinct is. So perhaps Cheesecake here, in this captive situation, has become such an excellent foster mother because her natural instincts to take care of little ones have kicked in. And I'm taking that one home. You know that, don't you? Yeah, you can have that one. Good stuff. The mothering instinct may come easily to a plant-eating supermum like the capybara. But can it explain why a predator would choose to mother what would normally be its prey? In Ireland, just outside the town of Clara, County Offaly, lives a young couple with the most remarkable story to tell. Ronan and Emma Lally own a small farm that they run alongside their day jobs. They have a lovely collection of animals but wanted some ducks to complete the picture. So they got in some fertilised eggs. On the day they hatched, Ronan went to check on them but couldn't find the ducklings in the barn. Within seconds of that, a cat jumped down from a pigeon hole within the shed over there and I kind of put one and one together and I just presumed that the cat had swallowed up the ducklings. At this stage, they were missing for about six hours so Ronan thought there was no hope at all. After searching round the farm, they eventually found the ducklings but unfortunately, the cat, Della, had got there first. I ended up catching the cat with a duck in her mouth at this stage and it really looked, Ronan was like, she's going to kill the ducklings. I was thinking, oh no, we're only after getting them back and now she's going to eat them right in front of us. Then, Emma noticed something unusual. I was like, Ronan, she's not actually forcefully holding this duck. That's when the amazing thing happened. We put the cat down, put the ducklings down and then all of a sudden the three little ducklings waddled straight underneath the cat. The cat lay down on her side, put her paw over one of the ducklings and was kind of nursing the duckling in towards her. So we were just absolutely blown away with this because normally cats would eat small birds but it was awesome, it was just incredible to see it. She was very content at this stage. She was purring and she was really loving towards the ducklings. When I was petting her down, I noticed that she actually had given birth to three kittens only within an hour or so beforehand. It was a very lucky coincidence for the ducklings that the cat found them just after giving birth herself. For a narrow window of a couple of hours, mothering hormones will have been coursing through her body causing her to love and nurture any small, warm, furry creature she found next to her. I have no doubt whatsoever that the cat was thinking dinner if she had seen them either maybe a couple of hours before or a couple of hours after. I have no doubt that she would have put the napkin around her neck, knife and fork, salt and pepper, the whole lot. But it was when they came to move the unusual family into a safer spot that they got an even greater surprise. As soon as we lifted up the cat, that's when we were totally amazed because the ducklings were actually latched on to the cat's nipples. They were hanging from her. Yeah, it was very bizarre. When we seen them breastfeeding, we just thought, oh my God, there's something very, very strange happening here and something very strange but also something very unique, you know. Duck mums don't produce milk and ducklings are born ready to find their own food and water from their surroundings. So to see them suckling a cat is extraordinary. Experts can only guess that their natural foraging instinct caused them to come upon the milk as an unexpected food source. And their desire for warmth and comfort kept them close to their foster mother. Ronan was keen to separate the ducks, fearful the cat's predatory instincts might kick back in. But Emma, being a midwife, recognised something that she regularly sees at work. There was just so much love there, you know, and, like, I see it every day in the labour ward. They just want to hold them, baby. It's so tight and close. It's a moment that just lasts forever and I could see that happening with the cat and the ducks. It just took me a while to convince Ronan. I said, Ronan, they're just so in love. They love each other. Like, you can't break this bond. It's amazing. Before long, the ducklings started to outgrow the kittens and gain their independence. Something the cat wasn't so happy with. These ducks, her yellow kittens, were a lot more active and she found it hard to control them. She was trying to bring them back underneath her and say, now, be good like your brothers and sisters. Several weeks later, the kittens are still small and the ducks, although independent, still have an attachment to their surrogate mum. So it would seem that this rare coincidence of a cat giving birth just as the ducklings were making their first steps into the world resulted in this remarkable situation. Filled with an instinct to mother small furry creatures, the cat ignored any natural urge to eat the ducklings and took the mum as her own. Now, it could be argued that all of this only happened because it was a domestic situation with animals that were unusually close to each other. But there are other examples that suggest the mothering instinct is so strong this can even happen in the wild. A few years ago, the most surprising example of misplaced mothering took place in Kenya. The story of this lioness and Oryx has an unhappy ending, but not for the reason you might think. A newborn Oryx, surely just minutes from being this lion's next meal. But to the complete amazement of the rangers who were monitoring the situation, the lioness didn't try to eat it. Instead, she cared for it as if it were her own young. Just like the cat with her ducklings, a strong instinct to protect and nurture was overriding the predatory instinct to kill it. Many theories were put forward as to why she was behaving in this way, and the consensus was that she was a young lioness who'd gone through some kind of traumatic experience involving being separated from her pride, and as a result, her mental state had led her to want to nurture this calf in some way. But unfortunately, the relationship came to a sudden end when the lioness took her eye off the calf for just a few moments. A male lion pounced and killed it. Witnesses described her behaviour as exactly that of a lioness who had lost her cubs. Heartbreaking to watch. Everyone thought that was the end of the story. But the lioness went on to adopt not one, but five more Oryx calves. Now, none of the relationships lasted as long as the first one, but this continuing fixation points to a traumatised animal desperate to nurture even if the young in question isn't her own species. The lioness was always going to struggle to keep the calves alive, especially as she wasn't able to feed them. But there is an example of cross-species mothering I've read about that caused a real stir in the scientific community because not only was it in the wild, but it was long-lasting. I've travelled to Sao Paulo in Brazil to find out what happened. Hey, over here. Hello there. These little fellas are called marmosets. They're one of the world's smallest monkeys. I mean, this is it. They get this big when they're fully grown. Is it even conceivable to think that one of these could be adopted by a completely different species out in the wild? They are so absurdly cute. I mean, well, Arnold wouldn't want to adopt them. And one group of scientists discovered exactly that. It occurred in a forest reserve in the heart of Brazil between a baby marmoset and a group of capuchin monkeys. I meet up with Professor Patricia Izar, one of the scientists who witnessed this rare event, the only long-term cross-species mothering that's ever been documented in the wild. When the marmosets encounter the capuchins, usually they go away. They are afraid of the capuchins. They hunt for small mammals, small rodents and marsupials and even small primates. So they've been known to eat a little marmoset or two, which makes this entire episode, which you were privy to, even more unusual. Yes. Suddenly, one day, the female appeared with a very, very tiny marmoset, probably days old. She was carrying the marmoset as if she was carrying her own baby. This in itself was extremely unusual, but what happened next almost certainly saved the marmoset's life. The capuchin allowed the baby marmoset to breastfeed. She was here with her mouth in the capuchin's nipple. We couldn't tell for sure that she was suckling, but she was in that position several times a day as a baby capuchin, as she would do with a marmoset mother, and she survived. What did you think when you first saw that? That, for us, was really, really amazing. That's unheard of. It's completely unique, this case, isn't it? Completely unique, yes. Over the coming months, the marmoset became very much part of the group, but there were some differences in the way she was treated. How does it manage to integrate into a group that's essentially very different in its behaviour, its ecology, everything? Yes, perfectly. Did it work well? Yes. In fact, the dominant male, sometimes we saw that he was treating her more or less like we treat our pets. So is this possible? Can animals, other than humans, keep pets? Patricia has some footage that sheds more light on the relationship. She just looks like one of the pebbles they use to crack the nuts. She's that small. I'm surprised we didn't squash her by accident. I mean, she's so tiny. Cracking a nut. Is she going to go in for some? And is he going to allow her? Yes, see the proximity. He's fine with her. Why do you think he's so relaxed? Because I think she's so tiny, tiny, tiny. He doesn't see her as a competition. He's watched her take some of the nuts. And that's OK. It's just adorable to watch it in action, isn't it? And he let her, you know. He's not stupid. He wouldn't let her do it if he didn't want her to. So is she like his little toy? She's so cute, he just can't help but let her get away with murder, compared to the other capuchins, you know. A wild animal keeping another species as a pet is unheard of and would be a hugely significant discovery. They're great to use as well. By the by, these are very clever monkeys, there's no question. Tool use was once considered a uniquely human activity, so could pet keeping be another behaviour that we share with other animals? We'll never know in this case, as sadly the marmoset disappeared after 14 months. Maybe a predator got her, or perhaps she joined another group of marmosets. But it does make me wonder if there are any other examples of animals that might keep pets and if this could be another reason for different species to hang out with each other. I've tracked down another unusual friendship from a clip I've seen on the internet. It might just be an example of pet keeping in animals and one that I can visit for myself. The animals in question live on the east coast of the US, near the tourist resort of Myrtle Beach in South Carolina. To track them down, I've headed away from the crowds to a quiet suburb on the banks of an inland river system. Here, an animal trainer named Doc Antle runs a wildlife safari park with an exotic collection of animals that includes a hound named Roscoe and an orangutan named Hanuman that appears to be treating the dog like a pet. Doc is currently training Hanuman to take Roscoe for a walk, but Hanuman seems to be taking it a step further. He just kind of holds on to you for security. I'm good with that. You're the tree at the moment. I can be a tree. How long has Hanuman and Roscoe been friends? They've known each other for the last seven years now. And how did it all begin? Because it is a bit of an odd couple, isn't it? They are an odd couple. They met each other by time that they spend down on the river. Doc often takes his elephant and some of the orangutans down to the river to cool off and have some fun in the water. But on one occasion, back in 2006, they came across a stray hound dog on their route. One of the orangs, Surya, jumped down and started playing with the hound and they instantly hit it off. Before long, all the orangs were playing and the dog had a new group of friends. They then grab each other and play and pet and start being kids, goofing around on the water. And it just engaged them, and they thought that he was a fabulous guy. At the end of the day, Doc headed back, hoping the stray dog would find its own way home. But the hound, who they later named Roscoe, had other ideas. The dog had made his way into the secure gated area and he was there with them. And they have a constant supply of food there and water. They put out the water for him and they also started taking monkey biscuits. Oh, no, he likes my biscuit. He's just going to look at it. They started taking monkey biscuits and handing him monkey biscuits. So they were like, we want to hang out with Roscoe. And Roscoe was in that state of really hunger and he ate everything they would give him until he looked like he'd swallowed a basketball. Dogs have evolved to be excellent pets, and for the orangs to be feeding and caring for Roscoe suggests they may have been treating him like one. But can that really be the case? If so, that is extraordinary. Now, we still think to this day, I think, that humans are the only animals that keep pets. But, you know, these orangutans are very closely related to us. They're great apes as well. Do you think it's even possible they think of Roscoe as a pet? I think that it is like a boy and his dog. He says, I've got my pet dog, we'll go out, we'll play fetch, we have an incredible time together. I love my dog. Now I'm drifting off, I'm with my parents, it's time for dinner, I'm going to go play baseball, and the dog becomes very secondary. I think it's more like that. They love him at the moment. I don't think they pine away for him or wonder where he is or miss him like you might see adult humans doing to a dog where they become really emotionally attached. Pet keeping can be defined as looking after an animal of another species with a level of care and affection, primarily for reasons of pleasure. And a very significant part of that care is, of course, feeding them. Whose is this? What's that? Do you want that? Yes. You want it. You want another one? Do you want to give it to Roscoe? No. Does he want it? Look, he wants it. You know he wants it. Yeah, you knew. See, he wanted to do it that way, though. Today, Hanneman hangs out with Roscoe whenever he can, and they seem to have a real level of affection for each other. They even go swimming together. Hanneman is only one of two apes in the whole world that can swim like this. Now, both Hanneman and Roscoe are obviously trained, so I wonder how much that affects what I'm seeing. To get a scientific perspective on their relationship, I've brought along Professor Hal Herzog, an animal behaviourist who's been investigating pet keeping in humans and other animals for many years. Amazing. See, eyes wide open, couple of bubbles out of the mouth, happily swimming in the pool. I've never seen that, have you? Never. Never. Hal, what do you make of this relationship? You've watched the orangutan and the dog. Well, there's a couple of relationships going on. The relationship with the orangutan and the dog is absolutely stunning, and it's very clear that they had a deep relationship. The thing that impressed me the most was food sharing, with the orangutan being perfectly happy taking orangutan chow, you know, not dog food. It was monkey chow. It was monkey chow, for sure. And giving it to Roscoe was quite stunning. So what do you think that means, that a great ape would share food with a completely different species? What do you think is going on in its head? I think to some extent it means that the great ape is recognising the existence of the dog as, in a way, a like-minded creature. It's treating it like a like-minded creature, just the way we would a dog or a cat in our lives. Do you think we can call this pet keeping? I would... Roscoe doesn't think so. Roscoe thinks so. You say yes, I say no. I say Roscoe said yes. I'm far too cynical in my old age. I don't. What do you think? I think the relationship that those guys have would fall into my definition of pet keeping. Really? Yes. Because for you to say that is a big deal. It is a big deal, but the thing that's interesting for me is that these relationships don't seem to exist outside human agency. And maybe the biggest part of the human agency is having a full stomach. Hal believes that in the wild, animals are too busy finding food and avoiding predators to have the time to devote to another animal in the way we might look after a pet. I argue that humans are the only animals that keep pets. Yes. Although you do see the rudiments of the motivation in other animals. And to me, what the orangutan here is doing is exemplifying that, that the rudiments of the urge to keep pets are right here in South Carolina. This is the perfect storm here. You've got a human being, Doc, who understands animals at a very, very deep level. You've got this ideal situation where there's plenty of food. And what this shows is that great apes, and probably a lot of other animals, are capable of deeply loving members of another species, but yet they don't seem to do it in the real world. As far as I know, with one exception. It was a case in Brazil where a group of primatologists discovered a troop of capuchin monkeys, and they adopted a two-month-old marmoset. I know the case. You covered it. Baby marmoset. Yeah. It's absolutely fascinating. And so what, to me, this does have the elements that you see in human pet keeping, is that the relationship is one of fondness. They're not getting anything out of it. They were feeding the creature. They liked it that much, and protecting it. But the other thing is it was long-lasting. To me, it's the closest thing to what I would call human pet keeping. But the thing is, it's one case of the millions of hours that primatologists have been, you know, spent with their glasses, you know, looking at trees. It's the only case. The fact that the potential for pet keeping exists in animals other than ourselves is revolutionary. But it's also forcing scientists like Hal to rethink what they know about animal minds. And that's what's been so fascinating about the journey I've been on. By looking at some of the most extreme, unusual and surprising animal friendships, we can gain a better understanding of the powerful instincts and needs that motivate all animals. Drives that are so strong, they can sometimes cross the species divide. But there is one last pairing that truly challenges what science knows about animal relationships. And that's because it involves a question of animal attraction and possibly even love. And to witness this odd couple, I'm visiting a safari park in South Africa, not far from Pretoria. To meet a kudu, a species of antelope, named Charles. He's a fine specimen. Charles is a male kudu, and he belongs to a wild herd here in this reserve in South Africa. Now, in a kudu herd, only the dominant male breeds at any one time, and the rest of the males disperse into bachelor herds or they become solitary kudus until they get the chance to usurp the alpha male and grab the throne. And Charles is one of these solitary males, for now at least. He's by the fence. However, this has incurred Charles's desire to find a mate, and in a neighbouring reserve lives a female he's taken a fancy to. When Charles was almost a year old, he began keeping company with a female he probably shouldn't be seeking out in the first place, and the only way he could reach her was by jumping this fence. Ah, there he is. Now, the fact that these animals can jump a fence this high without taking a running jump is pretty impressive. It also does show quite a bit of commitment for his lady love. And he's definitely on a mission. Now, ever since, he's followed her around, he's been hanging out with her, and the rangers have called this female Camilla. Now, just last week, for the first time ever, Charles tried to mate with Camilla, and it wasn't successful, to say the least, because Camilla happens to be a giraffe. I've heard that Charles has jumped the fence into the reserve, so if I'm lucky, I'll get to see them together. There he is. There's Charles. And he is coming down the hill to Camilla. God, he's so handsome. I can see why Camilla might be attracted to him. When they meet, they do seem to prefer spending time with each other rather than the other animals in the area. And it certainly looks like Charles and Camilla are more than just good friends. Charles and Camilla started hanging out when they were juveniles, so that does point to a relationship based on attachment hormones, companionship. But then it did turn into something a lot more primal. Now, in the wild, some animals have been known to be attracted to females from another species that resemble a fatter, healthier, more fecund version of their own species. But when you look at this kudu and this giraffe, it's kind of pushing that theory to the extremes, isn't it? So, is this a rare anomaly, or is it just that we haven't been able to understand this kind of behaviour yet? Either way, I love this story because it just goes to show how much we still need to learn about the animal kingdom. She's following him, guys. She's actually following him. Aw, really nice end to the story.