The hook
Every winter, hundreds of millions of monarch butterflies complete one of nature's most astonishing migrations, flying thousands of kilometres from Canada and the US to cluster in these few Mexican mountain forests, weighing down the fir branches and filling the air like drifting orange snow.
01Why it's worth it
The annual migration of the monarch butterfly is one of the wonders of the natural world: each autumn, hundreds of millions of these fragile orange-and-black insects travel up to four thousand kilometres south from eastern North America to overwinter in a handful of high-altitude fir forests in the mountains of Michoacán and the State of Mexico, an area so central to the phenomenon that it is a protected biosphere reserve. What makes it almost unbelievable is that no single butterfly makes the round trip; it takes several generations, yet each year they return to the very same groves their great-great-grandparents left, by means science still doesn't fully understand. Visiting in the winter season, you hike up into the cool, hushed forest to find the trees utterly draped in butterflies, entire boughs bending under their weight, and on warm, sunny days the colonies erupt into flight, filling the air with a shimmering, rustling cloud of orange in a genuinely overwhelming spectacle. It is seasonal, weather-dependent, and requires a steep hike at altitude, but few wildlife experiences are so moving.
02How to experience it
Come in the winter season (roughly November-March, best in the warm sun of late February), and hike or ride horseback up to a colony at reserves like El Rosario or Sierra Chincua with a local guide. Go on a warm, sunny day and midday for the butterflies in flight, keep quiet and to the paths, and prepare for the altitude and cold forest.