Each winter more than 150 million monarch butterflies migrate from the northeastern US and Canada to the Oyamel fir forests in the lush mountains of Michoacán in order to reproduce. It’s an amazing sight any time, but especially in January and February when numbers peak: whole trees are smothered in monarchs, branches sagging under the weight. In the cool of the morning, they dry their wings, turning the entire landscape a rich, velvety orange, while later in the day they take to the air, millions of fluttering butterflies making more noise than you’d ever think possible. As the afternoon humidity forces them to the ground, they form a thick carpet of blazing colour.
The best place to see them is in the Santuario de la Mariposa Monarca (middle weekend in Nov to last weekend in March daily 9am–4pm; M$55; wwww.santuario-monarca.com.mx), just outside the village of El Rosario, about 120km east of Morelia. It is best to go early in the morning (and preferably on weekdays, to avoid the crowds), when the butterflies are just waking up and before they fly off into the surrounding woodlands. Guides, whose services are included in the entry fee, show you around the sanctuary and give a short explanation of the butterflies’ lifecycle and breeding habits. For a couple of weeks on either side of the main season, those same guides run the place unofficially, still charging the entry price and offering their services for a tip. There are fewer butterflies but it is still worth the journey anytime from early November to early April. The walk to the best of the monarch-laden trees is about 2km, mostly uphill at an altitude of almost 3000 metres: take it easy if you’re not acclimatized.