The Survival of the Kangaroo: Bushfire, Drought, and Heat Waves (Full Episode) | The Kangaroo King

In this corner, one of the most pitiless landscapes in the world, the arid Australian outback. In this corner, one of the most resilient survivors in the world, the red kangaroo. With survival skills shaped by millions of years of evolution, it's now handed a knockout punch, a devastating drought. As thousands succumb to dehydration and starvation, one remarkable room may be facing death. Can he make it through this hell on Earth? Or is this one fight even the red kangaroo can't win? Australia, the oldest continent on the planet. Almost 3 quarters of it looks like this. At its center, it gets five inches of rain a year. The Mercury can hit 110 degrees Fahrenheit. The hardest part for those who live here is the climate's unpredictable personality. This is a place where there are no true seasons, only moons. To make it here, you need to roll with the punches and shift gears in a hurry. The acknowledged master of that art in the Australian outback is the red kangaroo, the largest marsupial in the world. This female is pregnant. Red kangaroo females are almost always pregnant. They evolve to adapt their reproductive systems to the unpredictable whims of the environment. At any given moment, a female can have three offspring to care for, each at a different stage of development. This is number one, the peanut. After 33 days developing in the womb, the newborn emerges as a blind, hairless pink creature, roughly the size of a peanut. We call him Rusty. There's virtually no sign of the powerful hind legs we all associate with the kangaroo. He uses his arms to make the grueling trek up the belly to his mother's nipple, guided solely by instinct and smell. Almost immediately, the female goes into heat again, releasing hormones that stimulate ovulation. Once fertilized, the mother's endocrine system puts the development of this new embryo on hold. That's offspring number two. The embryo won't continue its development until the peanut reduces his suckling. Number three is the joey. He spends some time suckling from outside the pouch and some out on his own in the big, wide world. The female is a living assembly line of young at various stages of development. But when times are hard, the system has to be ruthless. She will cut off nutrition to the peanut in her pouch, and when it dies, she'll restart the embryo's development to take his place. Rusty's growing up. He's beginning to resemble something like a baby kangaroo. Three months old, he can hear all the sounds of the world he'll soon be joining. It's all so unfamiliar, so it's not surprising he'd prefer to stay in the pouch a bit longer. There's plenty of food around now, and Rusty's mom makes the most of the good grazing. She doesn't eat much, but needs a particular type of grass for her nutrition. The shorter and greener, the better. She'll need to eat hardy. It's not a matter of whether hard times will come. It's just a matter of when. And Rusty needs the nutrition, too. It takes a lot of energy to grow ears like these. He's also starting to sprout fur, so mom has to modify his milk to supply more protein. By the time he leaves the pouch, the fat content of his milk supply will have doubled to be almost twice that of cow's milk, preparing him nutritionally for an active life outside the pouch. And Rusty has already been surveying his new world. About seven months ago, Rusty crawled into this world with arms twice as long as his legs, as mom relaxes her pouch muscles to release him. His legs are now more than twice as long as his arms. But Rusty's not the only one in the neighborhood with a serious set of legs. An emu, the biggest native bird in Australia, announces his arrival. His skirt of feathers absorbs 80% of solar radiation, leaving the skin underneath cool. And this dad needs a cool head. In the emu world, dads take on all parental responsibility. The chicks will be under his wing for 18 months. Not exactly the red kangaroo way. Males are pretty much deadbeat dads. They leave as soon as the young are conceived. Rusty still relies on his mother for food and protection, so he tends to stay close. But apparently, he's got an independent streak. Maybe there's even more fun out there. Soon, he leaves the rest of the mob and finds himself in uncharted territory, good place for a baby kangaroo to be. A wedge-tailed eagle, the largest bird of prey in Australia, and it likes to snatch young kangaroos. Mom realizes she doesn't know where Rusty is, but the eagle does. Rusty's big ears and instincts tell him something's not right. He's just too young and inexperienced to know what it is. No sooner has Rusty left his mother's side than he's in trouble with the bone-crushing power of her talons. The eagle could seize Rusty and drag him to his death. Suddenly, there's a flurry of panicked activity nearby. A rabbit runs for his life. Luckily for Rusty, there's easier prey to be had this time. Garoos and wedge-tailed eagles share the same territory. And when the eagle has a chick to feed, the hunting never stops. More than 10% of the eagle's diet is kangaroo. Rusty is now eight months old and a full-fledged joey, a juvenile that spends all his time outside the pouch. In a few months, he won't have mom's milk to rely on anymore. She'll taper off his milk supply because there's another peanut on the way, and it needs the nutrition. Mom's body now produces two totally different types of milk, a more dilute one for his tiny sister and a richer one for him, each dispensed from its own nipple. But males like Rusty are about 10% larger at weaning than the average female and are heavy drinkers. This is the kangaroo version of tough love. Rusty's mother cuts him off completely. Her milk is needed elsewhere. Now Rusty's off to explore his wider world. Before long, he finds another group of kangaroos. These are gray kangaroos, smaller than reds, and more suited to areas where the climate is relatively predictable. They don't conserve water as well as reds and prefer the shade of the wooded areas on the desert's edge. Rusty's apparently a new experience for them as well. It's like a get-together with distant relatives you've heard of but never met. Slightly awkward. Here comes another branch of the family, wallaroos, marsupials somewhere between red kangaroos and wallabies in size who frequent the rocky outcrops looking for shade and water. If you live in the desert, water is a treasure and its presence is never guaranteed. The only certainty is unpredictability. A waterhole is a gift from the heavens for many creatures. Emus, reds, and wallaroos all gather to drink. But the relentless sun is turning the mud around the waterhole into clay, laying traps for the unwary. Rusty is not driven by the same intense thirst as his gray cousins. Reds have a kind of super kidney which concentrates their urine so they hold on to more water. Grays have to drink more frequently, and their thirst can drive them to unwise decisions. This young gray is in trouble, deep trouble. And he's drawing some unwanted attention, a dingo. Dingoes will gladly take a young kangaroo under any circumstances. A joey stuck in the mud, unable to flee, that's just too good to resist. The other kangaroos can't help him. His fate is sealed. Even at the tender age of 18 months, Rusty has the good sense to get out of dodge in a hurry. A dingo is stalking the area. Kangaroo mobs can number in the hundreds, but this one is relatively small. Rusty's appearance on the scene catches another male's attention. They are around the same size and the same age, perfect sparring buddies. Game on. But this isn't a life or death battle. What they learn here will be crucial later in life when the stakes are higher. Long arms for wrestling win fights, and females want winners. Rusty doesn't come out on top this time, but the boxing experience is invaluable. At this age, the learning curve for a kangaroo is steep and full of surprises. A sudden rustle in the dry grass spooks the gang, but Rusty's the curious type, a shingleback lizard. Heavily armored and with a thick tail that looks a lot like its head, earns it its other name, the two-headed skink. Rusty wants to know what he's supposed to do with this. Make friends? Try to box with it? Eat it? The lizard doesn't seem suitable for any of these activities. Rusty eventually gives up on the relationship. This part of the central Australian outback has been hot and dry for weeks. The plants are picked clean. When food sources dry up like this, red kangaroos are superbly adapted to survive. Still, even they can't live without water. But something is happening 100 miles away, where the sky has opened up and torrential rains are soaking the parched earth. These waters will end up in the channel country and be funneled inland hundreds of miles away from their origin. The channels are dry now, but the region is low-lying, so they won't be for long. Now, what was once an arid wasteland begins to revive. From the swirling flocks of budgerigars to the dingo mom and her pups, all are drawn to the life-giving waters. The young eagle flexes its new feathers, and a young kangaroo celebrates in her own playful way. Emus are water guzzlers, and adults can drink up to four gallons a day. Like all emus, the chicks revel in a cooling bath. There are some half a million emus roaming around the outback, grazing on fruits and seeds. And what's good for emus is good for the rest of the ecosystem. As they move through the bush, they scatter the seeds of flowers and fruit they've eaten along the way, which will eventually sprout and become new plants. The weeks turn into months. Rusty is now five years old and in prime condition. Food has been his overriding concern, but now other impulses drive him. He's making the rounds of this gang, sniffing the females to pick out the receptive ones. He's now twice the size of some potential mates, but he's not quite in the size class of this bad boy. This is the king of the mob. Male reds grow throughout most of their lives. He looks like he's had a few brawls in his day, and he has about 50 pounds on Rusty. Big males who lose battles can be faced with a complete shutdown of their reproductive system. Rusty knows he's not ready for this bout, and wisely withdraws. Rusty was born to run, looking for mating partners, fleeing from predators, traveling to find food. Reds really shine when it's time to sprint. Yet kangaroo has one of the most efficient aerobic physiologies of any mammal, better than a racehorse and a lot better than us. Its heart is much bigger than you'd expect and twice the size of a deer's. But Rusty's mass is muscle, with 80% being concentrated around his pelvis and upper hind legs, putting him among the most muscular animals in the world. They're so efficient that they actually use less energy to breathe when they're hopping than when they're at rest. Red kangaroos are built to get where they want to go. Unfortunately, sometimes, especially when they're inexperienced, they get someplace they really don't want to be. The inland taipan is the most toxic snake on Earth. One bite has enough venom to kill 100 full-grown men. And this taipan specializes in killing mammals. Ah! The Australian desert is the kingdom of reptiles. And kangaroos know to leave all snakes alone. Brown snakes kill more humans than any other snakes in Australia. But it's not the biggest reptile in the neighborhood. This is the perentie, reaching eight feet long, venomous, and fast on its feet. A large perentie will eat a small kangaroo. Today, it's got its eye on an eastern brown snake. But the tongue of the perentie follows the brown snake's chemical scent trail and leads him to an abandoned burrow. A burrow with only one entrance. With a perentie in the picture, a sanctuary can easily become a death trap. The body of one fearsome reptile disappears into the body of another. The months roll on. And Rusty has grown in both size and experience. He weighs 150 pounds now and has dozens of sparring matches under his belt. Today, he finds himself with a mob he knows. The one with the tough male who intimidated him last time. But that was five years ago. And Rusty's not running away this time. Each tries to attack his rival's head, keeping his own head back out of range. Although highly ritualized, fights between dominant males can mean a future as king or a loner, depending on the outcome. Don't want those damaged. Rusty, with darker fur, puts up a good fight. But the alpha male is more experienced. Females don't care who wins, just as long as he's got good genes. Rusty is younger than his opponent. And in top fighting form, the king goes down. Now the mob pays him attention. Rusty's the top male. And the winner takes all. His first choice is this female. Though he needs to give her urine the sniff test, to make sure she's ovulating. She's ready. Rusty has only a brief window of opportunity. She may be receptive for only a matter of hours. Better get to it. Mating doesn't take long, or wouldn't if there were only one female to consider. But Rusty's got miles to go before he sleeps. He's king kangaroo now. And in addition to regular mating duties, he'll have to fend off young roos, who'd like to knock him off his throne, just as he did his predecessor. But that's not all Rusty has to worry about. The temperature is soaring, and the land is drying out. Evaporation is sucking the life out of everything. You can never tell when the weather will change, only that it will. And that's the origin of some of the red kangaroos' most amazing adaptations. They are masters of heat regulation. Fur on their backs reflects about 30% of incoming heat, and keeps their skin cool, the blue parts of this thermal footage. Spreading saliva over their forearms cools the blood, which has been brought close to the skin surface via a dense cobweb of capillaries. With temperatures simmering above 100 degrees for over a week, a third of the males have already become infertile. If these temperatures continue for three more months, the number would more than double. Reds defend their sperm by licking their scrotums to keep them cool. And in contrast to their battle strategy of retracting the scrotum, males let their testicles hang way down below their overheated trunks, keeping them about seven degrees cooler than at their cores. The sand, even a few inches down, is cooler than at the surface. Red kangaroos dig until they reach cooler soil, and then... It hasn't rained for months now. The dry, dead grass offers Rusty no nourishment. Then, unfortunately, these are dry electrical storms. No rain will come from them. But something else will. Something worse than hunger. Lightning ignited the dry grass of the outback. Almost 10% of arid Australia can burn like this in a single year. In a matter of hours, the fire consumes what little forage there is. Rusty has to move on. But there's really nowhere to go. Not this time. Parts of desert Australia are in the grip of a once-in-a-century drought, while heat waves smash temperature records. Nothing that lives here has ever experienced anything like it, Rusty included. Some suffer from severe malnutrition and dehydration. But if anyone can survive this, it's a red kangaroo. Human bodies are about 60% water. Rusty's is more than 70%. Heat wave like this, he can survive levels of dehydration that would kill most humans. Reds only sweat when they're on the move. At rest, they pant, which uses less water than sweating. Raising their breathing rate to over 200 breaths a minute reduces their deep body temperature and cools their brains. And of course, they cover their limbs in cooling saliva. But there's a price to pay. Licking uses up precious water. If the drought continues much longer, this form of cooling will be too costly. The kangaroos stay under whatever shade they can find. When times get this tough, females switch off their milk supply. Maternal instinct is strong, but self-preservation is stronger. Unweaned offspring outside the pouch are the first to die, and young in the pouches are next. As it dies, the female reactivates her waiting embryo. But if the drought persists, it too will die, and she will stop reproducing altogether. Even Rusty, one of the strongest, is in trouble. In these conditions, males are the first to succumb, especially the largest, who, like Rusty, need more food. The demise of a red kangaroo is the wedge-tailed eagle's bounty. But it's not just kangaroos that are suffering. The drought takes its toll everywhere. Predators turn on each other to protect a tiny piece of rancid meat. This is the last remaining waterhole. It's stagnant and salty. Ordinarily, animals would never drink this water, but desperation drives them. This is a sign of things to come. Heat waves in Australia are becoming hotter and more frequent. The intense dry heat continues, and the casualties mount. Among them are many of Rusty's offspring. In some parts of these desolate lands, drought can kill eight out of every 10 kangaroos. Australia's desert inhabitants are a resilient bunch. After all, these may have been the hottest temperatures for the last hundred years, and this species has successfully weathered their hot climate for tens of thousands of years. Rusty is still here, conserving his energy and biding his time. But a change is going to come. It always does. After 12 months of merciless drought, the landscape is dotted with the remains of those that could not hang on any longer. But in the Australian outback, all bad things come to an end. Eventually, thunderclouds gather in the distance. Rusty seems to sense a change in the weather. Somewhere there is rain, and where there is water, there will soon be food. He just has to get there. With what remains of his ebbing strength, Rusty heads in the direction of a storm, as do the other red kangaroos who have made it this far. When Rusty reaches the area watered by the storm, he finds a world restored by rain. To eat, plenty to drink. You can almost see the relief and joy in their hopping. The roos will stay here and take in the nourishment. In only a few weeks, males and females will have their health restored, and soon, they'll be ready to reproduce once again. But before that can happen, they have to make it through this, a pack of hungry dingoes. Hunting in a pack more than doubles a dingo's success rate. Normally, they'd go for the weakest kangaroos in the group. But a pack of this size can take down something bigger, something like Rusty. His strength is completely restored, and he can travel at full tilt. Rusty doesn't accelerate by bounding faster, but by bounding further. He lengthens his leaps, at times covering 25 feet in a single bound. Once he gets past 10 miles an hour, Rusty rockets along with little extra effort, while the dingo's four legs need to move ever faster. At 25 miles an hour, Rusty's using only about half of the energy the dogs are putting in. They have no chance of catching him. Now, Rusty can turn his attention to replacing the offspring lost to the drought. 200 powerful pounds, and in the prime of life, there's no question that he's the dominant male in this gang. The young He Fathers will need an advantage to survive a world as harsh and unpredictable as this one. What greater advantage could there be than to begin life as the progeny of the undisputed king of the red kangaroo mob?