Wonders of the Monsoon

From India to Australia, all life awaits the transforming power of the monsoon rains. Our story begins in the southern extreme of the monsoon region, northern Australia. It is the end of the dry season and 300,000 little red flying foxes gather to drink. They skim the river, collecting water on their bodies, but they run the gauntlet of Australian freshwater crocodiles that launch out of the water to catch them. The sun-baked continent causes hot air to rise, sucking moist monsoon winds in from the coast and dramatic electrical storms herald the first rains. A frilled lizard wakes from his torpor to hunt insects, displaying his startling frills to defend his territory. On Christmas Island, the rains trigger an amazing spectacle - millions of red crabs migrate from the forest to the coast in order to spawn. Whilst they wait for rain, a mother Sumatran orangutan guides her youngster to where she knows a fig tree fruits at this time of year. Across the region, the dependability of the monsoon has been the foundation for great civilisations. But the vast ruins of Angkor in Cambodia bear testament to what can happen when monsoons fail. The Indian monsoon approaches. In the Delhi stock exchange, the price of rice escalates every day the rains fail to materialise. In an ancient ceremony, priests submerge themselves in water and beseech Varuna, god of water, to come. At a shrinking waterhole, chital deer gather nervously. This is the most dangerous time of year. A tiger is bearing down on them and not all will live to see the revitalising rains. Peacocks begin to display as they sense the monsoon coming. On the horizon, bubbling clouds are approaching. The first drops of the monsoon appear on the parched ground. At last the monsoon is here.

With a whisper on the wind, pre-monsoon showers come to Thailand. Assamese macaque monkeys play in the waters and gorge themselves on a monsoon delicacy of water snails. To the west, in India, huge banks of cloud roll in, heralding four months of incessant rain. The rains trigger a dramatic response. Male Indian common toads are transformed yellow-gold for just one day. It is their big chance to mate. Within days, insects are everywhere. New filming techniques show, for the first time, how mosquitoes survive the impacts of giant raindrops. Fresh grass draws nomads and their vast herds of livestock back to their homelands. But they are stalked by hungry wolves and hyenas, which move in at night for the kill. In the far northeast of India, exceptional rain from the Bay of Bengal combines with meltwater from the Himalayas to create catastrophic floods in the river Brahmaputra. It floods Kaziranga National Park, forcing a herd of elephants to make the perilous journey across a busy road and come into conflict with humans before they can reach the safety of the hills. In Cambodia, the Mekong swells so much that water is forced backwards up its tributary, the Sap, to fill the vast Tonle Sap Lake - one of the most productive freshwater fisheries on earth. It is time for the comical 'snakebird school', where darter chicks learn how to catch fish. Under the water, the sinister frog-faced soft-shelled turtles lurch out of the river bed to snatch passing fish. Finally, monsoon rainwater flows back through the great rivers of Asia to the Indian Ocean. It brings with it a vast lode of nutrients. Year round, blue whales congregate off the coast of Sri Lanka in search of the bounty that the monsoon brings.

During the part of the year that the monsoon doesn't bring rain, the winds reverse, bringing instead dry air and even drought to large parts of the region. Fed by the previous rains, budgerigars swarm in the Australian desert. They congregate at a precious waterhole. Birds of prey try to ambush them but are mesmerised by the kaleidoscope of yellow and green. On Borneo, one bearded pig has worked out a strategy for surviving this lean time of year. He heads straight for the beach and uses his snout to hunt for seafood. Ghost crabs burrow deep into the sand, but the pig's snout sniffs them out and digs them up. In the Rajasthan desert, drought-loving camels provide vital transport for its inhabitants. Pushkar hosts the world's largest camel fair early in the dry season. Amongst the attractions, nomads haggle over the price of a camel. In Sri Lanka, now that food is hard to find, Asia's largest gathering of elephants is seen at an ancient man-made lake, where the receding waters unveil fertile areas of fresh grass. At a nearby waterhole, the mugger crocodiles stalk the prey that is forced there to drink. But a young leopard, learning to hunt under the cover of darkness, discovers that there is no easy meal. On the golden plains of India, blackbuck take the challenge of the drought head-on. Young bucks battle at noon to find out who is tough enough to get the territory and the females. Finally, the monsoon winds reverse once more. They will soon bring rain again but only after the sandstorms...

Between Australia and Asia, sit thousands of rain-drenched tropical islands, many pocked with volcanoes and each a strange, unique world of wonderful life. Killer leeches, volcano worshippers, loving monkeys and monstrous carnivorous plants all thrive here, thanks to the unusual world in which the monsoon comes not just once, but twice a year.

Our story begins as the relationship began - humans entered the region as hunter-gatherers. On the Philippine island of Palawan near Borneo, for part of the year people still hunt in the forest and live in caves. As with their ancient forebears, their lives are underpinned by a closeness to and a spiritual respect for nature. Around 10,000 years ago, rice - the perfect monsoon crop - changed everything. In the paddies of Assam, India, farmers battle a herd of hungry elephants over the rice crop. Conflicts like this have played out for thousands of years. But this tension in the relationship has been softened by another phenomenon - organised religion. Both Hinduism and Buddhism have deeply influenced the relationship - teaching a deep respect for nature. We meet a group of the Bishnoi sect who believe that all life is sacred and have been known to lay down their lives for nature, even to protect trees. As a consequence of this philosophy, their marginal farmland supports a higher density of people than any other desert in the world. Across India, thousands of sacred groves are reserved for the worship of nature. For thousands of years, wildlife that lives in these areas has been protected, helping to keep the subcontinent the bio-diverse place that it still is. But the relationship now faces a challenge from worldwide demand for the Monsoon's bounty, especially the clearance of forests for cash crops. The most visible casualties are iconic species such as siamese crocodiles, bengal tigers and orangutans, as their habitat is stripped from around them. But even here there is hope. Local people are figuring out how to harvest both the natural timber and crops that the world wants, in a more sustainable way. Whatever the future holds for the lands of the monsoon, all of us are now connected and surely have a part to play.