In the eastern-most corner of Michoacán, straddling the border of México state, lies the incredible 563-sq-km Monarch Butterfly Reserve, the site of the butterfly Burning Man. Every autumn, from late October to early November, millions of monarch butterflies flock to these forested Mexican highlands for their winter hibernation, having flown all the way from the Great Lakes region of the US and Canada, some 4500km away. As they close in on their destination they gather in gentle swarms, crossing highways and fluttering up steep mountainsides where they cling together in clusters that weigh down thick branches of the oyenal (fir) trees. When the sun rises and warms the forest, they take to the sky in gold and orange flurries, descending to the humid forest floor for the hottest part of the day. By mid-afternoon they often carpet the ground brilliantly. The best time to see them is on a warm, sunny afternoon in February – they don’t fly as much in cool weather.