Monarch butterflies

Every year, one of the most spectacular natural phenomena in Mexico takes place in the forested mountains west of Mexico City. Between mid-January and late March, colonies of monarch butterflies migrate here from colder northern climates to find warmth and begin their breeding season. These huge flying colonies may contain as many as 20 million butterflies, and they can travel up to 160 kilometres per day.
© Sylvain Cordier/Minden Pictures