A guide leads a horse 11,000 up the Cerro Chincua mountain at the Monarch Butterfly Biosphere Reserve in Cerro Chincua central Mexican in Michoacan State. Each year hundreds of millions Monarch butterflies mass migrate from the U.S. and Canada to Oyamel fir forests in the volcanic highlands of central Mexico. North American monarchs are the only butterflies that make such a massive journey—up to 3,000 miles (4,828 kilometers).
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