Walking Among Monarchs

West of Mexico City, high in the oyamel fir forests of Michoacán, millions of monarch butterflies spend the winter clustered on the mountainsides. The trees bend orange under their weight, and on sunny afternoons the air itself seems to move as thousands take flight at once. Standing inside the colony, with butterflies settling on hats and shoulders, is the signature moment. November through March is the overwintering season, with February at its peak. Other sanctuaries cluster nearby at Sierra Chincua and Piedra Herrada, while California's coast hosts the smaller western overwintering sites such as Pismo Beach.