Award winning wildlife photographers Jonathan and Angela Scott have travelled the world, always returning home to Kenya. There they introduced the world to the big cats of the Maasai Mara and now they are part of its fight for survival.

From steamy jungles to dry deserts, amphibians have taken their first footsteps onto land using their bizarre life histories to break their ties with the water and invade the earth.
This episode delves into the extraordinary and intimate lives of the soft skinned amphibians. This includes the marsupial frogs, a peculiar species where the father carries his young in pouches and then gives birth. It also features warring giant salamanders over a metre long and show-off newts that offer displays just like underwater birds of paradise.

David Attenborough reveals the fascinating lives of snakes, the most misunderstood group of reptiles. A CCTV stakeout of wild rattlesnakes hunting shows, for the first time, what sophisticated predators they truly are. Attenborough is also on the receiving end of a spitting cobra's chemical weapons system, while the surprisingly beautiful and tender side of snakes is displayed in the sinuous courtship of kingsnakes, and the water birth of 15 beautiful yellow anaconda babies.

The world of the armoured creatures is equally fascinating and bizarre. Galapagos giant tortoises solve the problem of making love in a suit of armour; a heated sea turtle orgy leaves females in mortal danger and we witness the explosive arrival of a baby pig-nosed turtle. Giant salt-water crocodiles crowd a flooded river-run to fish for mullet and a caiman leads her brood in a touching trek to a communal crèche.

Every year grizzly bear families in North America depend for their survival on a spectacular natural event: the return of hundreds of millions of salmon from the Pacific Ocean to the mountain streams where they were born. The salmon travel thousands of miles to spawn and then die. The great run not only provides food for bears, but for killer whales, wolves, bald eagles, and even the forest itself. The question is: will the salmon return in time to keep hungry bears alive?
A mother grizzly and her cubs emerge from their den high in snowy Alaskan mountains. Filming from the air the team capture a TV first, following the bears as they negotiate a near vertical slope on their journey to the coast where they await the return of the salmon. Meanwhile, the salmon are making their way to the to river mouths where they must swim upstream and against the current. The programme reveals how they tackle the torrents and leap over waterfalls, a feat equivalent to a human jumping over a house. Dozens of hungry bears eagerly await the salmon that make it up river. In another TV first, underwater cameras record the ingenuity and fancy footwork they use to collect dead salmon from the bottom of deep pools.

Each year more than one million wildebeest and zebra invade the Serengeti grasslands, making it a paradise for the predators that live there. But what happens when the herds move off again? We follow the moving story of one lion family's struggle to survive until the return of the great migration. Nature's Great Events tells the story of the epic trek of herds that follow the rains to fresh pastures, and the tale of the predators they leave behind.
The crew captures the desperate plight of a single pride of lions, revealing a different side to the Serengeti. Rather than being a predators' paradise, it is a land in constant change, with wildebeest following the rains and leaving the lions to tough it out. The Ntudu pride has seven cubs, and is already suffering as the wildebeest leave to find fresh pastures. The four pride females struggle to find enough food for their hungry offspring. As weeks turn to months, the pride members become more emaciated and frailer, and the number of cubs dwindles to just two. As the herds begin to return, the plains reveal one final secret. For the first time since 1967 the Serengeti's only active volcano, Ol Doinyo Lengai, begins to billow ash and smoke. Filmed from the air, the team captures the exciting action. Fertilised by the volcanic ash over millions of years, these short grass plains are among the most productive grasslands in the world. After months of hardship, the pride's tragic story, through sickness, drought and fire, is over as the herds return, providing plentiful food.