Robot Spy Hummingbird Films HALF A BILLION MONARCH BUTTERFLIES

Up to half a billion monarch butterflies lie sleeping having overwintered in Mexico. As winter ends and spring arrives, the sun warms their wings and the forest comes to life as a cascade of butterflies take flight Robot Spy Hummingbird is right there in the heart of the spectacle. Clip taken from episode 2 The North of the second series of Spy in the Wild, narrated by David Tennant. Catch up on the series on the BBC iPlayer here: Spy