Many of Hashem's creations perform astounding feats. One place where we can spot His handiwork is in the amazing annual migration of the monarch butterfly. Monarch butterflies (Danaus plexippus) perform annual migrations across North America which have been called “one of the most spectacular natural phenomena in the world."
Monarchs can travel between 50-100 miles a day; it can take up to two months to complete their journey. The farthest ranging monarch butterfly recorded traveled 265 miles in one day.
The eastern population migrates up to 4830 miles (7,778 km) to overwintering sites in Mexico. Starting in September and October, eastern/northeastern populations migrate from southern Canada and the United States to overwintering sites in central Mexico where they arrive around November. They start the return trip in March, arriving around July. Similarly, the western populations migrate annually between regions west of the Rocky Mountains including northern Canada and overwintering sites at the coast of California.
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No individual butterfly completes the entire round trip; at least five generations are involved in the annual cycle
No individual butterfly completes the entire round trip; female monarchs lay eggs for the next generation during the northward migration and at least five generations are involved in the annual cycle. Fall-migrating monarchs are not the same ones that migrated northward approximately five months before. Instead the northern-migrating butterflies are at least five generations removed from overwintering sites.
Theories that explain monarch migration are many. "Science has not yet offered a sufficient explanation for how that [the migration] happens." Researchers often propose that multiple migratory mechanisms play a role. Not all who study monarch migration agree on the mechanisms that allow the migrating butterflies to find overwintering sites.
It is proposed that the ability to find overwintering sites in California and Mexico is an inherited trait. It has also been called a genetic memory. The possibility of an inherited map has been posited suggesting that the butterflies may follow streams and recognize landmarks. Other studies provide evidence against the theory of an inherited map.
Sources: Wikipedia; United States Department of Agriculture Forest Service