The fifth instalment is set in Botswana, where the arid plains of the Kalahari are transformed into a lush wetland by the annual flooding of the Okavango Delta. The Okavango River is charged by rain falling in the Angolan highlands, but it is months before the water arrives at the delta. Meanwhile, thousands of animals follow ancient migration routes across the desert, braving dehydration and punishing heat. New elephant behaviour is filmed as they skim their trunks delicately across the surface of a stagnant pool, siphoning clean water from the upper layers. The transformation of the desert into a green oasis is filmed using time-lapse photography, whilst sequences shot with macro lenses show the changes in much finer detail. For the first time, vast clouds of dragonflies are observed emerging to mate and lay their eggs. Larger animals make the most of the sudden riches the new landscape offers. Male hippos plough through the newly-formed waterways and battle for dominance, red lechwe bound through the shallows and huge flocks of wading birds arrive to breed. Elephants and buffalo face one final challenge before they reach the delta; a pride of hungry lions. The lions attack in broad daylight, bringing down an elephant calf. The making-of featurette, "Mission Impassable", follows the crew as they struggle to cross ever-deepening waters to reach and film the front line of the advancing flood.
Nature's Great Events is a wildlife documentary series made for BBC television, first shown in the UK on BBC One and BBC HD in February 2009. The series looks at how seasonal changes powered by the sun cause shifting weather patterns and ocean currents, which in turn create the conditions for some of the planet’s most spectacular wildlife events. Each episode focuses on the challenges and opportunities these changes present to a few key species. Nature's Great Events was produced by the BBC Natural History Unit in association with the Discovery Channel and Wanda Films. The British version of the series was narrated by David Attenborough. In the USA, the series was shown under the alternative title Nature's Most Amazing Events beginning on 29 May 2009 and was narrated by Hasani Issa. The title Nature's Great Events was previously used by Reader's Digest for a unrelated VHS series released in 1996. Source: Wikipedia