Episode Three: Plant Predators

Some of the biggest predators to walk the earth face a constant battle -- their prey is heavily armoured, often indigestible, sometimes even poisonous, and what makes this struggle between predator and prey the more remarkable is that these predators do not prey on animals, but on plants....

Although we live on a green planet, eating plants presents one of the greatest challenges to mammals, shaping them and their lives in the most extraordinary ways. The sloth is 'half blind, half deaf' and moves at a snail's pace -- an extreme example of what can happen to you if you live on nothing but leaves! Plants arm themselves with deadly weapons, from razor sharp spines to deadly poisons, but plant predators are not deterred. The elusive tapir of the South American jungle visits secret clay licks in search of a natural antidote to the poisons. The pika, or rubble rabbit of the Canadian Rockies has found a way to make poisons work to its advantage, exploiting them as a natural preservative. But sometimes the problem is not what's in your food, but what is not -- we bugged the caves of Mount Elgon to reveal startling images of underground elephants mining for salts deficient in their green diet. Even the great wildebeest migration is now understood to be driven by the need for minerals....

The next great battle that plant predators face takes place on the open plains -- behind every plant-eater lurks a meat-eater. For once we see the hunt from the plant predators' point of view; wrap-around vision, ears that rotate 360 degrees and elongated limbs make it harder for them to be caught than most wildlife films would make you think....

Plant predators are equipped with dangerous weapons used in the greatest battle of all -- with each other. We witness the drama of the annual bison rut in the Badlands of North America, discover the secret of the battering rams of the big-horned sheep of Canada, and analyse the fighting technique of horned animals as they ram, wrestle and stab their opponents.

Amazing to think that all these extraordinary behaviours stem from the apparently simple act of eating leaves....