Eight new natural wonders added to World Heritage list | Environment | guardian.co.uk

The three core zones of the Monarch butterfly biosphere reserve protect eight overwintering colonies of the monarch butterfly in the oyamel fir forests of central Mexico. Perhaps a billion monarch butterflies overwinter here in close-packed clusters every year after a 3,500-4,500km journey. Witnessing this unique phenomenon is considered to be an exceptional experience of nature
Photograph: Frans Lanting/Corbis