Scotland’s Frozen Frontier: A Winter of Survival in the Highlands (4K Documentary)

It's October in the Northwest Highlands, and the forests of Glen Africa are flushed with gold. It's a still, crisp, perfect morning, but this is a shallow beauty. With the brief summer now past, the animals of the Highlands are in for the long haul. The next few months will see them driven to desperate measures as they prepare for the lockdown of the Highlands' longest, darkest, and most overwhelming season. It'll be April before the sun rises clear of these peaks again. Some take flight, seeking refuge in the warm South, but those that remain will need every drop of resilience they can muster. Only the toughest will survive what the elements are about to throw at the Highlands. Here among the mountains, you have to be perfectly adapted to make it through. With four of the five highest peaks in the Highlands, this is the most extensive alpine terrain in Scotland. At these altitudes, heavy snow can arrive in almost any month, and it lies here all year round. But one animal has got what it takes to live here. Once extinct in these mountains, but living and breeding here once again, they're reindeer. Reintroduced in the 1950s, after an absence of over 8,000 years, they're better adapted to these extreme conditions than any other Scottish mammal. Like many of the world's reindeer herds, people look after these animals. But for most of the year, they're left to fend for themselves on these wild hills. Calves are born in the spring, but reindeer are large animals with an eight-month gestation period. So to make the most of the good times, they need to mate now, before the winter lockdown takes hold. In their short rut, triggered by decreasing day length, a dominant male will try to mate with as many females as possible. Each will only be receptive for a short time, so it's crucial the rut happens now. This distinctive dark male has ruled the herd for two years. But this year, he's got competition. This paler bull is exactly the same age, but he's never beaten the dark male, so he's been unable to father even a single calf. This year could mark the end of his losing streak, but he'll need to pick exactly the moment for his challenge, and he's only got a few days to do it. The Cairngorms National Park is by far the biggest in the UK. Larger than Luxembourg, it contains more native forest than any other part of Britain. Much of this is evergreen Scots pine, but there are over 10,000 acres of broadleaf woodland here too. In these forests, autumn is a fruitful time, with the trees casting berries and nuts on the forest floor. They're a critical food source for red squirrels. This little female has already seen more than her fair share of winters. At six years old, she's already lived double the average for a red squirrel. Perhaps it's the richness of this place, with its supply of beech and hazelnuts, which has sustained her for so long. She's not alone here. Bearing a distinctive battle-scarred nose, her neighbour is almost as old. Outside the breeding season, red squirrels are usually tolerant of each other, but these two constantly compete over the available resources. Tail-swishing means keep your distance. But all this scrapping is using up valuable energy, and the long haul hasn't even started yet. Although the Highlands are known for their clear autumn days, October and November are amongst the wettest months of the year, with rain falling on two out of three days. But this autumn deluge is a critical part of the life cycle of one animal, Atlantic salmon. Here at the Falls of Shin, 30 miles north of Inverness, big numbers are gathering. Returning from their 2,000-mile ocean migration, they're getting ready to move upriver. Their eggs can only survive in the shallow headwaters of Highland rivers, high up in mountains, so raised water levels present them with their best chance of reaching the spawning grounds. They must time it right if their offspring are to survive and make their own journey out to sea. But there's a problem. The Falls are blocking the salmon's path. There's only one way to get around them, and that is to go over them. It's a game of persistence and luck. Launching themselves above the sill requires formidable acceleration. Their muscles are adapted for short, sharp bursts of energy. Leaps can cover more than three meters, and although they fail time after time, their desire to push on is so strong they never give up. But clearing the Falls is only the first challenge. Ahead of them lies a grueling journey to their spawning grounds on the western fringes of the Highlands. Back on the Cairngorm Plateau, the pale reindeer bull has made the decision to challenge the dominant male. It's a well-timed move. The dark bull has been mating and he's tired. To win the fight, the pale bull will need to force his way up the hill and drive the ruling male down into the valley. But the dark bull takes the initiative and moves down to block his rival's advance. Grunting and pacing are all part of the build-up. Game on. Reindeer battles can carry on for many hours. Rarely fight to the death. They're equally matched. It's all about who'll tire first. They're close to exhaustion, but neither will back down. Little by little, the pale bull pushes his rival up the slope, and it's all over. They're both completely exhausted. The dark male doesn't have the spirit for another round and heads for the edge of the herd. For the first time, the pale bull will have his chance to breed. In the forest, the red squirrels are working frantically. Hoarding food is an important way of getting through the coldest months, and the old squirrel is burying nuts on the forest floor. Before each nut is stored, it's assessed. Weight and smell will tell her if it's good or bad. And as she handles each one, it's marked with her unique scent. A good spatial memory and a highly developed sense of smell will allow her to find it later in the winter. But the forest floor is a dangerous place for a tree-loving mammal. A pheasant is no threat. But birds of prey like buzzards will readily snatch an off-guard squirrel. She freezes on the spot, with her eyes fixed on the danger. She's safe. But while she's been sitting tight, her neighbor has been helping herself to the cash. Remarkably, the old squirrel has a strategy to deal with this and confuses her thieving neighbor by pretending to bury a nut before moving it elsewhere. It looks like a game. But these preparations are urgent and serious. A cold front is sweeping in from the east. The highlands are on the cusp of winter. 80 miles east, on the Aberdeenshire coast near the Loch of Strathbeg, visitors are arriving for winter. Pink-footed geese. They've traveled more than 600 miles non-stop from their breeding grounds in Iceland. To them, the highlands offer a sanctuary from the unbearable conditions further north. Over the next few months, they'll spread out across the fertile wetlands on the edges of the highlands. More than 80,000 will arrive on these beaches after their marathon journey. But they can't rest here long. It's 48 hours since they've fed and they must head to more fertile grounds. It's early November and animals are making their final preparations for winter. 90 miles north, on Coppensey in the Orkney Islands, one of the last and most dramatic events of all is playing out. Every other highland animal completes their breeding cycle in summer. But grey seals are an exception to the rule. Breeding now because it takes the whole of summer and early autumn to feed themselves into peak condition for pupping. Once they're on the beaches, neither females or males will feed. And all births will happen in just a few weeks. This pup was born weighing 13 kilos. But because grey seal milk is 50% fat, he'll gain two kilos a day, more than trebling his weight in just three weeks. Once he's weaned, the mother will turn her attention to the bulls. She's looking for one type of bull in particular, the biggest and strongest. This huge battle-scarred male controls the beach and its harem of females. The smaller bulls don't challenge him. They sit on the waterline, testing each other's strength in the shallows. But the dominant bull doesn't get involved in small skirmishes. He doesn't need to. The female seal swims straight to him, bypassing the younger, less dominant males. Grey seal courtship starts with splashing and scrapping. But unusually for a large mammal, it then relaxes into a tender embrace. Soon, both mating and pupping will have to cease, as the biggest storm of the season is on its way. Back on the mainland, the weather is settled. And the salmon are on the move. Their journey from coast to spawning grounds can cover many miles. And the complete trip can take more than six months. They don't eat anything on their migration. So why they strike at an angler's fly is still a complete mystery. But the vast majority evade even the most skilled fishermen. The fish are driven ever onwards by an ability to sense unique chemicals from the remote mountain burns where they spent the first few years of their lives. After an extraordinary journey, they finally come home. And now they're ready to complete their life cycle. Females seek out sheltered positions where their eggs will have the best chance of survival. The males have changed dramatically. To show dominance, their jaws have curved upwards, exposing rows of ferocious looking teeth. Charged with testosterone, this male's intolerant of any imposter, even a juvenile salmon. He moves in on the female. Using her body, she digs a hollow in the riverbed where she'll safely lay her eggs. She's ready. The male moves in, releasing his sperm as the eggs appear. The salmon have completed their breeding cycle. Conditions may be calm in the northwest. But on Koppensee, it couldn't be more different. The storm has arrived. Wind gusts can exceed 100 miles an hour on this exposed coast. And the waves tower to more than 12 feet. Climate change may be behind the increase in huge storms like this. Potentially disastrous for wildlife. The grey seal pups are too young to swim. So they're hauling themselves up onto the field beyond the beach. This one's become separated from its mother. It's tired and hungry. At just a few days old, it needs two and a half litres of milk a day to survive. If it can't find its mother quickly, it'll die. Other females are highly territorial and attack pups in their patch. So it must keep moving to stay alive. In sheer desperation, it tries to suckle from another pup's flippers. It's weakening fast and burning precious energy. Malnutrition is the most common cause of death in seal pups. But astonishingly, the mother has found her way back to the lost pup. And at last, it's safe. As the sea calms, something remarkable happens. Cannibalism. The dominant bull is feasting on the carcass of a pup. Possibly one swept into the waves by the power of the storm. This strange and disturbing behaviour is a recent discovery. Hardly ever seen and never filmed before. Scientists aren't sure why grey seals have turned cannibal. It could be pure hunger or dwindling fish resources. But whatever the reason, the behaviour seems to be on the increase. With the breeding cycle completed, the male salmon lies exhausted in the water. As spawning salmon don't eat once they enter the breeding cycle, their muscle fat will only sustain them for a limited period. He's a shadow of the powerful fish that leapt the falls back in early October. Despite these incredible challenges, 5% of salmon actually make it back to the ocean. But not this one. His body will now become food for the same tiny creatures that will sustain his own offspring once they hatch. It's now mid-November and the highlands are looking straight into the jaws of winter. For the first time since March, temperatures drop below zero and it starts to snow. A heavy fall like this early in the season is rare. But soon the entire region from Glencoe in the west to the high tops of the Cairngorms is coated in fresh powder. But this is the beginning of the winter lockdown. With grass and heather buried beneath the snow, the struggle for the animals will inevitably become tougher over the next few weeks. But these conditions are perfect for one species, which is flocking to the mountains in droves. Humans. With five resorts and up to 100 days of snow a year, the highlands have been an important ski area since the 1950s. The ski centre on Cairngorm Mountain is also a magnet for wildlife, a ptarmigan. This arctic member of the grouse family is at home on the very highest peaks of the Cairngorms and western highlands. Able to survive on a meagre diet of heather, they molt into a pure white plumage for the winter. There are white mountain hares here too. They can also survive on the withering shoots at the edge of the snowfield. There's a reason why the ptarmigan and hares choose to live here. As the winter lockdown sets in, predators like golden eagles range widely to find food. But they're shy birds and will stay away from human activity at all costs. So as long as the ptarmigan and hares stay close to the skiers, they should remain safe. But it's a dangerous game. Although the eagles won't venture near people, they're less troubled by the lifts and buildings. So the ptarmigan and hares need to keep watch at all times. By December standards, it's been a huge dump of snow. In Abernethy Forest, at the foot of the Cairngorms, the drifts lie deep. Small birds like crested tits are now vulnerable. In the UK, they're only found in these highland forests. The breeding population is around 2,000 pairs. But a harsh winter can decimate their numbers. A resident of the canopy in the summer, winter brings them down to the forest floor to feed. Like red squirrels, crested tits cache food. And it's a matter of urgency to dig up the stash of seeds for fresh energy. Small songbirds are unable to carry much fat, so they need to feed constantly. They've got competition. Coal tits will raid crested tit caches. And even though the crested tits are bigger, persistence pays off. But squandering energy through fighting would be dangerous now. The lockdown has only just arrived, and far worse is on the way. Pressure is falling, and storm force winds hammer in from the west. It's a blizzard. But these are the conditions that make reindeer such masters of the highland winter. Reindeer coats are double layered. A dense fuzzy underfur provides a warm base. And the long outer hairs are hollow and filled with air to provide superb insulation. Even feeding is no problem. The powerful winds prevent the buildup of snow, and having huge spade-like feet means that reindeer can easily dig up heather and lichens. Ptarmigan also take the blizzard in their stride. Their thick winter plumage includes feathers around the feet that act like snowshoes. The snow bunting also has warm feathers around its tiny toes. Up to 15,000 of these migrants arrive in the highlands in winter, and often follow animals like reindeer, to take advantage of the food exposed by the scraping and digging. The blizzard is easing. But 60% of the highlands have now been covered by snow for the best part of three weeks. And the flakes just keep on falling. For the red squirrels, food caches are a lifesaver. But supplies are running desperately short. And now, where there were once two squirrels, just one remains. Unable to cope with this savage opening to winter, the older female has already succumbed. The old squirrel's death has thrown a lifeline to her neighbor. Able to exploit twice as many food caches, her chances of surviving this brutal winter have been significantly raised. The highlands are now approaching the winter solstice. The longest night of the year. In the highlands, this means more than 18 hours of darkness. But the rule of night is challenged. The northern lights. Generated by gas in the earth's atmosphere, colliding with charged particles from the sun, the lights can dance until dawn. And now, each day, the sun will rise a few minutes earlier. The light is returning. The weather is warming too. Although the snow still lies deep from the Trossachs to the Cairngorms, the thaw has begun. The small rise in temperature is triggering new behavior from the ptarmigan and hares. The beginnings of courtship. Female mountain hares can come into season in the depths of winter if temperatures climb above freezing. And males will try and find as many receptive mates as they can. But the females are picky. They'll outrun, outbox and vault clear of any male they don't consider fit and athletic enough to mate with. Unlike the hares and most of their grouse relatives, ptarmigan will seek out a single mate. But at this point in the season, it's more about chasing other males around the resort. The white creatures will need to be very careful now. Their lives depend on their camouflage. And the thaw has started to expose clear patches of heather. If the snow melts early, there'll be an easy target for the eagles. Further down the mountain, the hills are now completely clear of snow. Black grouse, close relatives of the ptarmigan, are also starting their mating displays. Although the females won't appear at these courtship sites called leks until the spring, the males compete year round. They're working out who's the dominant bird. It's a three-way contest to gain control of the best spot in the lek. The wheezing calls and plumped up feathers are all part of the display. But the real clincher is the eyebrows. Large eyebrows are a sign of high testosterone. And the bigger and brighter the brows, the more attractive the male will be to females in the spring. As the hours of sunlight increase, the thaw picks up pace. Even high on the peaks, the patches of exposed heather are growing. Perfect camouflage for red grouse. But the hares are now at risk of attack from the eagles. Mountain hares always flee uphill because eagles need height to strike. This closes the gap and reduces their ability to manoeuvre. The eagle flushes a ptarmigan and switches target. But the eagles aren't the only predators here. Ravens can also kill a tired hare. But hares can run at nearly 45 miles an hour. So it stays out of reach and slips into the heather just in time. It's unusual for snow to lie in the whole highland region for more than a few weeks. Although it's still only January, the temperatures have at last started to climb above freezing. Rivers and berms now churn with meltwater. And the highland animals are at last granted a brief reprieve from the onslaught of winter. Even now, there are signs of the season's end. New spring salmon have started to enter the river systems. Embarking on the same epic journey that ended for others only two months ago. These spring salmon are revered by highlanders. On the great rivers like the Dee, Tay and Spey, they're given a hero's welcome before the river is opened for the fishing season. Lord of creation, we ask that you will bless this living water of the Spey. River flow, fill our hearts with joy and gladness and thanksgiving always. Whiskey is poured into the river. A gesture to wish the salmon good health. And at last, with great anticipation, the anglers can cast their lines. The seasons have come full circle and spring feels close at last. The animals that have survived the challenges of the long haul will now face up to the intensity of spring. With an uncertain future for our climate, living wild in the highlands looks set to become more extreme than ever. But this living landscape has been changing and renewing itself for millennia. So the Scottish highlands will always be one of the world's most magical wild places. Next time, the people of the highlands. Over the centuries, many of the riches of these wild places have been lost. With forests cut down and wild animals driven to extinction. But now they're returning. Never before have so many people found new and surprising ways of putting back what we've lost. you