David Attenborough returns to the island of Madagascar on a very personal quest. In 1960, he visited the island to film one of his first ever wildlife series - Zoo Quest. Whilst he was there, he acquired a giant egg belonging to an extinct bird known as the 'elephant bird' - the largest bird that ever lived. It has been one of his most treasured possessions ever since. Fifty years older, he now returns to the island to find out more about this amazing creature and to see how the island has changed. Could the elephant bird's fate provide lessons that may help protect Madagascar's remaining wildlife?
Using Zoo Quest archive and specially shot location footage, this film follows David as he revisits scenes from his youth and meets people at the front line of wildlife protection. On his return, scientists at Oxford University are able to reveal for the first time how old David's egg actually is, and what that might tell us about the legendary elephant bird.

Mammals' ability to learn new tricks is the key to survival in the knife-edge world of hunters and hunted. In a TV first, a killer whale off the Falklands does something unique: it sneaks into a pool where elephant seal pups learn to swim and snatches them, saving itself the trouble of hunting in the open sea. Slow-motion cameras reveal the star-nosed mole's newly-discovered technique for smelling prey underwater: it exhales then inhales a bubble of air ten times per second. Young ibex soon learn the only way to escape a fox - run up an almost vertical cliff face - and young stoats fight mock battles, learning the skills that make them one of the world's most efficient predators.

The great flood in the Okavango turns 4,000 square miles of arid plains into a beautiful wetland. Elephant mothers guide their families on an epic trek across the harsh Kalahari Desert towards it, siphoning fresh water from stagnant pools and facing hungry lions. Hippos battle for territory, as the magical water draws in thousands of buffalo and birds, and vast clouds of dragonflies. Will the young elephant calves survive to reach this grassland paradise? The experienced mother elephants time their arrival at the delta to coincide with the lush grass produced by the great flood.
In a TV first, the programme shows the way they use their trunks to siphon clean water from the surface layers of a stagnant pool, while avoiding stirring up the muddy sediment on the bottom with their feet. Lechwe swamp deer, zebras, giraffes, crocodiles and numerous fish and thousands of birds arrive in the delta. And, in a phenomenon never before filmed in the Okavango, thousands of dragonflies appear - seemingly from nowhere - within minutes of the flood arrival, mating and laying eggs. As the flood finally reaches its peak, elephants and buffalo, near the end of their epic trek across the desert, face the final gauntlet of a hungry pride of lions. In a heart-wrenching sequence, a baby elephant is brought down by a lion in broad daylight.

Around 30% of the land's surface is desert, the most varied of our ecosystems despite the lack of rain. Unravel the secrets of desert survival and experience the ephemeral nature of this dynamic environment. Watch Saharan sandstorms nearly a mile high and desert rivers that run for a single day. In the Gobi Desert, rare Bactrian camels get moisture from the snow. In the Atacama, guanacos survive by licking dew off cactus spines. In the USA, the brief blooming of Death Valley triggers a plague of locusts 65km wide and 160km long. A unique aerial voyage over the Namibian desert reveals elephants on a long trek for food and desert lions searching for wandering oryx.

After filming for three years, Planet Earth finally captures the shy Mongolian gazelle. Only a handful of people have witnessed its annual migration. Don't miss the bizarre-looking Tibetan fox, captured on film for the first time. Over six weeks the team follow a pride of 30 lions as they attempt to hunt elephants. Using the latest night vision equipment, the crew film the chaotic battles that ensue at close quarters.

The documentary deals with the future of conservation. It begins by looking at previous efforts. The 'Save The Whales' campaign, which started in the 1960s, is seen to have had a limited effect, as whaling continues and fish stocks also decline. In the 1990s, as head of the Kenya Wildlife Service, Richard Leakey took on the poachers by employing armed units. Although it was successful in saving elephants, the policy was detrimental to the Maasai people, who were forced from their land. The need for "fortress" areas is questioned, and the recently highlighted Raja Ampat coral reef in Indonesia is an example. The more tourism it generates, the greater the potential for damage — and inevitable coastal construction. Sustainable development is viewed as controversial, and one contributor perceives it to currently be a "contradiction in terms". Trophy hunting is also contentious. Those that support it argue that it generates wealth for local economies, while its opponents point to the reducing numbers of species such as the markhor. Ecotourism is shown to be beneficial, as it is in the interests of its providers to protect their environments. However, in some areas, such as the Borneo rainforests, the great diversity of species is being replaced by monocultures. The role of both religion and the media in conservation is argued to be extremely important. Contributors to the programme admit a degree of worry about the future, but also optimism.