Wild Iberia | Episode 4: Winter | Free Documentary Nature

In just four days, Christmas will be here. Every day at dawn, frost announces the arrival of winter on the inland of the Iberian peninsula and kills off the mushrooms of autumn. Life is sleeping in the trees of Spain and Portugal because of the cold. We have passed from the ochre shades of the leaves in the fall to the naked grey of the branches and leaden skies. Winter is here. The sun, when it shows its face on the days that it manages to pierce the clouds or the fog, doesn't rise very high above the horizon. This makes it even colder and the temperatures can fall to minus 20 degrees Celsius in some places like the Aragonese province of Teruel. In December of 1963, the temperature reached minus 30 degrees Celsius. Although that doesn't scare the cranes because where they come from, it's even colder. The mountains that surround the great city of Madrid also awaken under a mantle of frost. Sierra del Guadarrama National Park is a surprising place with enormous masses of granite and dizzying slopes. It's hard to walk over the rock formations known as La Pedrita and nobody can run over them except for the Iberian ibex which protects itself from predators by scrambling to the highest of these rocks. Beginning in November, the drop in temperatures leads the males to descend from the mountain peaks at an altitude of 2,000 meters. Since the previous spring, they've stayed far away from the females and their kids. But the mating period for this very tough species takes place precisely when the air gets nippy again. The females like to make the determined males court them tenaciously. It will be a long time before they let the males mount them. What the male does with his tongue as he tries to convince her may look odd. But that's so he can use the sense organs in his mouth to analyze the pheromones that indicate at what point of ovulation each female is in. Many days will go by, several weeks even, before the big male will be accepted yet another year. It's essential that the production of their sexual cells be precisely synchronized. And she won't accept him until she's sure that she can be impregnated. It seems it's still too early for her. By the end of December, all the females will have been mounted. Only the strongest males, the ones with the biggest horns, the ones with the darkest coats, the toughest ones, are accepted by the females. The Iberian Ibex's process of natural selection includes one of the most explosive and dangerous combats in the animal kingdom. Some of these battles can last close to an hour. And the most curious thing is that the ones that fight are actually the deputies of the big alpha males. In this way, the Iberian Ibex avoids having to fight many young males one after another, which might exhaust the great sultan and threaten his right to reproduce. But in any case, the females are always the ones who say yes. Or no. The Iberian Peninsula covers almost 600,000 square kilometers. 15 Iberian peninsulas would fit in the Sahara desert, and 10 in the Amazon river basin. It represents only 5% of the surface area of Europe. And yet the value of its wildlife isn't proportional to its size. These lands are exceptionally important because of their diversity and their geostrategic location. And in the south, quite close to Africa, from the Algarve on the Atlantic Ocean to the beaches of the Mediterranean Sea, it never freezes over. Africa is only an hour away as the crow flies, or even less. Many travelers make round trips from one world to another, especially in spring and autumn. These geese, however, arrive in winter. But that's because they aren't coming from the south, but rather from beyond the Arctic Circle. Their food in Scandinavia is frozen now, and they've come in search of chufa sedges, an aquatic plant that grows in shallow waters. The root of the chufa sedge is very tough, and a little sand in your gizzard comes in really handy to digest it. The sand from the dunes in Doñana will help the geese with the job. In winter, the geese gather together in huge flocks of up to tens of thousands of birds. Only very specific and very rich ecosystems can sustain them, such as the wetlands of the Guadalquivir River, the mouth of the Tagus River south of Lisbon, or the lakes of Iafafila in Zamora province. This cold region of Spain must remind them of their northern home, because they receive the low temperatures like an old friend. At nightfall, the geese seek refuge in the water to sleep safe from the wolves, foxes and wild boar. But at night, and during the early dawn hours from December to February, these shallow waters freeze over. That is, unless thousands of geese are continuously paddling with their feet, preventing ice from forming and trapping them. That's why the water in the area along the shore where the geese have slept isn't covered with a hard sheet of ice like the rest of the lake. The temperature of the water is below freezing, but by moving their legs, the flock has kept it liquid. Their plumage, oiled and appropriately combed, is the perfect insulation to prevent their skin from coming in contact with the water or the air. Their legs minimize the blood flow, so the loss of body heat is minimal. This species is perfectly adapted to winter's low temperatures. In the Pyrenees, winter is always white and freezing cold. But the blood of the ravens is boiling in the depths of January, at an altitude of more than 3,000 meters. The ravens have chosen to fly over the windiest and most difficult peak today, because it's time to show the rest just what each one of them is made of. The flocks of ravens band together in winter to perform acrobatic tricks. These aren't mere practice runs. Their dive-bombing and loop-the-loops are risky. Flying so close to each other, at high speed, with strong gusts of crosswinds and low visibility, increases the likelihood of their losing control. And just a slight sprain, a twisted wing, would mean sure death up here. There's no doubt that these birds' intellectual capacity allows them to enjoy this game. And they do with any object. They have fun taking it away from each other. But the ultimate aim isn't playful. The pairs are synchronizing their biological clocks and strengthening their emotional bonds. Almost all of them will end up finding a mate. Although they aren't looking for the best bird, or the strongest one, or the bravest one, but rather for the best match. The bird that they synchronize with well. In many parts of the Iberian Peninsula, the winter cold and snow complicate the efforts to get food each day. It's the time of year that produces the first deaths. Discarding the extra animals that were born the previous spring. As the cold approaches, the starling's social behavior changes radically. In the spring, they raise their chicks while living in isolated pairs. And then during the autumn, they gradually join their neighbors in small groups to feed. Now, in winter, they gather together in large flocks to sleep. Sometimes in flocks numbering in the millions. The idea is for the younger starlings to occupy the outer areas of the flock, on the perimeter, which is the most dangerous area because that's where predators attack. The most experienced starlings almost always fly in the center of the flock, where they are protected by the insurmountable shield formed by so many unseasoned rookies. In exchange for risking their lives, these young starlings learn how to fly better. And above all, where they have to look for food and shelter at nightfall. Each of the last three days, at dusk, they've been attacked by two sparrowhawks when they had settled in the branches to roost. And in the air, by a peregrine falcon. That's the only bird able to beat them up above. But three casualties a day, among a population of three million, isn't a significant loss. And besides, statistically, they must have been the individuals that didn't know how to move in sync in that same split second as the other members of their squadron. But thanks to that culling, each year the flocks of starlings fly better. By mid-January, the period of hibernation has entered the toughest phase. Underground, buried inside tree trunks, or submerged in freezing cold water, many living beings lie in wait, their lives temporarily on hold. A good number of them will never wake up again. Hibernation isn't easy. The most common frog on the Iberian Peninsula, Paris's frog, is one of the amphibians best prepared to withstand low temperatures. Even freezing. If ice crystals form inside a living organism, they cause irreparable damage that almost always leads to death. The water dissolved in the cells enlarges when it freezes and breaks the cell membranes and walls. The animals that have to survive extreme temperatures while hibernating have substances that protect them from freezing and that limit the increase in volume of each cell even if it freezes. This is an essential adaptation that both invertebrates and vertebrates have developed so that they can hibernate without dying. Hibernation is an excellent strategy. A process to isolate oneself from the harsh continental climate or the severe weather in the high mountains, which prevent many animals from getting food or even digesting it. It's effective because the cold keeps an animal's body temperature very low while it sleeps and so it minimizes energy consumption to practically zero. If the sun gets a little warmer for a few days, it allows some hibernating animals to wake up and move around a bit, even go out for a short walk or drink a little. But that scant heat isn't enough to carry out metabolic processes so they have to go back to sleep again. Birds don't know how to hibernate and besides, in the southwest of the peninsula near the border between Spain and Portugal, it gets cold but not very. The griffon vultures have begun to fly in pairs. And the male and female follow each other for hours. When they take a break, they try out different rocks to choose the one they like best for the platform for their future nest. The Salto del Gitano, one of the most emblematic places in Spain's Manfragüe National Park, is the site of one of the largest colonies of this species in the world. The population of griffon vultures was declining until only a few decades ago. But now they're bouncing back and bringing balance back to the countryside. Nobody hibernates on the southern coast of Iberia. Here, during the worst period of the year, the skies get a little cloudy and at most the temperatures drop to 5 or 10 degrees Celsius. But the weather doesn't get truly cold. Although there are fewer insects and fewer arthropods, like the brine shrimp that flamingos feed on, that forces them to spread out. To find their food, they have to stir up the mud with their feet, stamping their feet as if they were dancing flamenco. The lukewarm southwesterly winds help the flamingos to fly home again and also sweep a lot of African sand to the wetlands of Damiana, creating an ecosystem of sand dunes that is very rare. The plant species that have adapted to this type of substrate, with hardly any moisture and very few nutrients, create a barrier of stems and roots that holds the sand in place a little. That's what gradually forms each dune. But sand is like a liquid and can't sit still. Dunes move. Nothing can keep them from advancing completely at a speed that ranges from 3 to 6 meters a year. That's very slow movement, but eventually they will reach the marshes and will sink into them and disappear. In rainy years, the force of the water will sweep the sand away and carry it back to the sea, closing the circle. But on their journey, the dunes kill everything in their path. They line up like the waves on the sea. Here there are six main lines of dunes. The vegetation finds a place to live in the space between each line of dunes, but only for a limited period of time. Stone pines manage to form magnificent thick forests. But the moving dunes eventually surround them and gradually bury them all. Or almost all. Every once in a while, a pine tree sprouts in the right spot or grows a little faster and taller than the rest. And it isn't smothered to death because the sand can't quite cover it completely. That's the exception, the witness to the dunes passage and perhaps the future of a new species of stone pines. Wetlands and marshes are ecosystems where biodiversity concentrates. This is especially evident with respect to water birds. There are a lot of water birds here and a great variety of species of water birds. And if there are birds, then there are fish and invertebrates and vegetation and predators. The role of these valuable wet habitats is crucial. The marshes of Santonia, the mouth of the Tagus river, the Ebro river delta, the wetlands of Doñana or Daimel. These are perhaps the most important ones both for native species and for the migratory species that use them as places to rest and feed on their journeys. Certain duck species even spend whole seasons here when the climate in their countries of origin is inhospitable. Now the birds that winter in Iberia are numerous. Although at this time of year, they may not be visible every day. Frequently, the bad weather forces them to seek shelter among the reeds and bulrushes and the landscape looks empty. The presence of wolves is becoming normal again in the northwestern half of Iberia. Perhaps where they are most abundant is from Montesinho Natural Park to Peneda Gerês, the only national park in Portugal. Every day, these populations cross the border between Spain and Portugal, heading for the Sierra de la Culebra mountain range and even reaching the Ancares range in Galicia, crossing and strengthening their genes and their bloodlines. The protection of these lands is proving successful and an ecosystem where an apex predator can reproduce is a healthy ecosystem. Likewise, the Iberian wolf is also colonizing its old territories south of the Duero River again. It has even reached the mountains in the center of the peninsula near Madrid. The cold winter nights once again bear witness to the sounds of the new packs reclaiming the lands that they used to roam and organizing themselves to hunt. Although March is almost here, last night was the coldest night of the year in the forests of Alzain, in the central mountain range, at an altitude of almost 2,000 meters. The sharp pine needles are tough, like the spines of a cactus, and the leaves of these trees can bear both searing heat and bitter cold. In reality, almost everything in this land of extremes is prepared to survive temperatures ranging from the minus 20 degrees Celsius now to more than 30 degrees in summer. That's an atmospheric temperature range of 50 degrees. 150 kilometers farther south, as the crow flies, in Caballeros, the land has also suffered a severe frost. The cold takes the lives of many of the animals here. This red deer couldn't withstand it, but it also favors the natural selection of the best adapted individuals. This fox is taking full advantage of the opportunities that luck has offered it. Foxes are hunters, but like almost all predators, they don't turn their noses up at good carrion. But the vultures have already discovered it and are in no mood to share. Nobody here would dare to confront so many vultures. The griffon vultures of the Iberian Peninsula have no trouble finding food in either cold or hot weather. Somebody is always dying for them. This species was threatened with extinction here only a few decades ago, but now its population has bounced back. The griffon vultures are now beginning to choose mates and getting ready to raise young. The females are about to lay eggs and their needs and hunger are greater than at any other time of the year, and that's why they're fiercer too. Eurasian eagle owls raise their young in the worst of the cold weather, even earlier than vultures. These chicks were born a few weeks ago, but some even broke through their shells in January. Rodents, rabbits, even foxes and the occasional kite are prey that are always present in the nests of one of the world's largest nocturnal birds of prey. Owls, like all apex predators, help to keep the gene pool of their prey healthy and balanced. They hunted night, making the most of the opportunities that they perceive with their sharp eyes, In southern Aragon, tens of thousands of cranes, like the geese, are hiding in the water during the night, where they trust they won't be attacked by carnivores. The cold is still reluctant to leave, although it's weaker now and has little time left. The march equinox is just around the corner and the cranes are waiting for a thermal sign to begin the trip home. But the sign hasn't appeared yet. This morning brought a very thick fall and the drops of water are sticking to everything, but the sunlight is growing warmer and warmer. The nights are growing shorter and the cold is less intense. Today, the water hasn't frozen, as it had been freezing in many rivers and lakes in the interior of the Iberian peninsula. In winter, radiation fog is produced by the heat lost by the soil and water during the night and rises in the form of tiny water particles that remain suspended in the air. In the twilight between the darkness and the day, a faint light envelops the water vapor before the bright sunlight makes it possible to see everything and everyone clearly. This is the time of day that many hunters prefer because they have a greater chance of success. Now is when there is a greater chance of seeing an otter. The conservation efforts made in Spain and Portugal, aimed at cleaning up and improving the condition of the rivers and lakes, has allowed this emblematic species to proliferate again. From Galicia to Andalusia and from the Alentejo to the Pyrenees, wherever there are crayfish, fish and amphibians. Many amphibians find the weather conditions in February and early March favorable for reproduction, but in these lands, even in winter, milder days frequently pop up and that allows the natterjack toads, among others, to start singing. The water temperature is crucial for their tone of voice because it affects their vocal cords. The sounds that the males make attract females according to the timber. For them, the ideal thing is for the water to be at about nine degrees Celsius. The amphibian orgy takes place in a very short period of time and depending on the weather, each body of water has its own special day. In most toad populations, 90% of the mating occurs in just a few hours on the same day or two days. Some toad copulations last up to 20 hours, although the hardest part isn't lasting that long, but rather not being able to keep hugging each other while being pestered by all the males that didn't find a mate at the start of the evening. And there are more males than females, sometimes 20 times more. Many of them will never reproduce. This one is desperately trying to break up the sexual grip of a mating couple, but it's almost impossible to undo their copulation once the fertilization process has begun. It would have to break the arms of the male that legitimately earned the right to procreate. Amphibians don't usually wait for springtime to fulfill the task of multiplying their number. They, and especially their tadpoles, depend on the water not evaporating or soaking into the ground too soon. And sometimes spring arrives dry and hot, which can be a death trap for their offspring. But this time the development processes seem to be going well, and the worst freezes are over by this time in March. The polliwogs will have to hurry up and grow up. The griffin vultures in the southern mountain ranges, from Cazorla to the Sierra Morena, and also in Monfragüe National Park, have noticed the changes in the air. Their hormones have set their nerves on end. The best concealed nests, the ones in the best places, the ones on the flattest spots, the ones on the steepest cliffs, or the easiest ones to reach, are fiercely defended. There aren't very many places to choose from, and the difference between a sheltered nest, or one that's big enough, or one that's stable, and one that's not, is decisive for the survival of each chick. The first few have already hatched. They're the riskiest bets, but if they survive, they'll have a big lead on the rest of the colony. They'll have to be ready to fly when summer and the heat arrive, when many animals will die of thirst to feed the next generation of vultures. The ice that so often made it hard for the cranes to drink is thinner today. That's another sign that everything will change soon. These cranes breed in the north, from Sweden to Russia, where they came from in autumn, of these birds make it clear that everything is finally warming up. A few seem to be crazily happy. Their ritual dances form the first mating pairs. They may make the return trip together, but just in case, it's a good idea to get to know each other little by little, because when spring makes its appearance, it's time for them to go. Today is the 21st of March, spring. Not one crane is left. Theoretically, the coming months are a little muddy. Changing weather, unpredictable behavior, urgency to be born, to eat, to survive. It's the start of a new cycle that kicks off when the plant kingdom and its flowers awaken. It's time for sex, wrists, and beginning anew.