Although the Mekong runs down Thailand's far eastern border, the influence of the river's basin reaches across nearly half the country. The east of Thailand is characterised by a complex network of the Mekong's tributaries. These waterways are the foundation of life for many different ecosystems; from extensive rice fields to large pockets of tropical rainforest. The forests are multi-layered ecosystems with different species living at every level. Gibbons live in the high canopy, and the pileated gibbon is perhaps one of the most elegant. This episode features an intimate portrayal of a tight knit family: a male, a female and their infant. Pileated gibbons are monogamous and both parents cooperate in taking care of the young - unusual among primates. The infant gibbon will be independent enough to start exploring his surroundings under the watchful eye of his parents. Though life in the wild won't be without its perils, up in the canopy gibbons have a good chance of staying out of harm's way. The under-story is where the predators roam. A poisonous pit viper is almost invisible among the forest foliage. Sensing its environment, it's trying to catch the smell of a meal. With minimal vision the Pit Viper locates its potential prey using an infrared heat sensing organ that detects warm-blooded animals. Unfazed by potential danger, a large group of pig-tailed macaques crash through the under-story. A low network of branches provides a fun arboreal jungle gym for the unruly juveniles. The alpha male needs to assert his authority, maintaining his place at the top which to took him years attain. The Mekong's tributaries also provide the water that irrigates Thailand's extensive rice fields. These rice fields support diverse food webs. Crustaceans and small fish attract rodents, reptiles and wading birds, which in turn attract flocks of migratory raptors. The rice fields host some of the largest gathering of birds of prey on the continent. As the Mekong's tributaries twist and turn through the paddy fields, they pass by some of the most spectacular creations in the bird world. Baya weavers weave impressive nests that hang like baubles from trees, their intricate structures must impress potential females. Whether it be building a home, evading danger or raising a family, all animals by the Mekong River face the same challenges in life.