91热爆

When massing for their winter torpor in Mexico, the pine trees laden with Monarch Butterflies are one of the most mystical and magical places to be.

David Attenborough is one of many naturalists, writers and broadcasters to marvel at this species migration feat and the spectacle of their over wintering - one of the natural wonders of the world.

David guides us through the butterfly's migration to Canada from Mexico - and back again - gently unpacking their natural history and wonder.

He also immerses us in other butterfly congregations during filming trips over the years - but in a clever twist brings us back to his garden with an intriguing thought about the evolution of butterfly behaviour.

Written and presented by David Attenborough.

Producer: Julian Hector

First broadcast on 91热爆 Radio 4 in May 2011.