Zitácuaro: The Monarch butterfly migration

Stretched out on the ground in a mountain clearing, I gaze up at the blue sky set ablaze with orange and black wings dancing against a breeze. Indigenous legend says that Monarchs are the returning spirits of warriors and children. Encircled by mighty oyamel trees bending under the weight of thousands of resting butterflies I close my eyes and listen to the hum of brilliantly colored wings and it seems plausible.

Image:Luz Montero

Only in a delicate pocket of Mexican highland forest can the Monarchs survive the winter.

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The mountains in the Macheros Sanctuary, tucked just outside the town of Zitácuaro in eastern Michoacán, are alive with the flutter of the travelers from afar. Only here, in a delicate pocket of endangered Mexican highland forest, can the Monarchs from Canada and the eastern United States survive the winter.

The Monarchs’ journey begins in August when they set out on the same path their great, great grandparents did one year ago. Relying on circadian rhythm and the position of the sun to guide them, the butterflies migrate south, arriving in November and leaving again in March.

Scientists are still baffled by many aspects of the annual migration, but it is now widely believed that the Monarchs’ ancestors were tropical butterflies that ended up in northern climes as a result of chasing their ever-depleting life source -- milkweed. Despite this, Monarchs never evolved to hibernate in order to survive the colder weather, and so each year they must return south when winter comes.

Straddling the Michoacán and Estado de México border, the Macheros Sanctuary remains relatively unspoiled by the crowds that flock to neighboring sanctuaries. Many are daunted by the trek there, a steep hour-and-a-half climb on horseback and then by foot. I find the hike exciting. As we ascend through cool shadows and patches of sunlight the first traces of treasure appear -- the glitter of a fallen wing and the occasional butterfly, drifting alone.