Monarch butterfly cluster (Danaus plexippus) over a sacred fir (Abies religiosa) at ‘El Rosario’ reserve in Michoacan, Mexico. Every year millions of Monarch butterflies migrate from Canada and the United States to it’s hibernation site in the fir forests of Michoacan, where they cluster together over the ‘Oyameles’, this behavior works not only for protection but also for energy conservation.