Right about now, millions of monarch butterflies are transforming the forests of Michoacán, Mexico into a swirling sea of orange and black. As temperatures dip, they’ll limit their movements and eventually settle into large, dense clusters to wait out the winter. They deserve the rest. After all, each butterfly started out somewhere in the northern U.S. or Canada and traveled as far as 3,000 miles to reach this temperate home away from home.
Even more impressively, the monarchs embark on this annual migration without a GPS to guide them — or even an old-fashioned map. And they can’t ask their parents for the best route; because of their short lifespans, only about one out of every five generations of monarchs migrate. It’s no wonder they’re the only butterfly species known to make a two-way migration, just as birds do.
Unfortunately, climate change and deforestation are now raising concerns about the ...
