At 2,000 miles long, Mexico is a vast country and one that is dominated by a great mountain range – the Sierra Madre – the focus of the first programme in this three-part series.

The mountains are home to an amazing array of wildlife, including Mexican black bears which are filmed cheekily sneaking a drink from water troughs built by ranchers for their cattle.

There is also the breathtaking sight of hundreds of millions of monarch butterflies covering the trees high in the mountains.

Believed by Mexicans to be the spirits of the dead, the creatures’ arrival coincides with the spectacular Day of the Dead festival.