Living Acres

Southern Migration

August 30, 2016

Monarchs on Tree

The monarch migration is an annual occurrence that leaves many scientists and butterfly enthusiasts in awe, and for good reason. No other tropical butterfly travels as far as the monarch, which flies between 50 to 100 miles in a day. Monarchs are also the only butterfly species to make a two-way migration path.

Typically, beginning in October, monarchs begin their migration south because they are unable to survive long, cold winters, unlike other insects in temperate climates. Monarchs that spend the summer to the west of the Rocky Mountains stay within the United States and stay in the groves of eucalyptus trees along the California coast.

Monarchs east of the Rockies fly out of the U.S. and overwinter in the oyamel fir forests of Mexico. The oyamel fir forests are located at an elevation of nearly 2 miles above sea level, which provides the monarchs with the ideal climate. The temperature ranges from 32 to 60 degrees Fahrenheit and the humidity levels ensure the butterflies do not dry out allowing them to conserve their energy.  

When traveling southward, the monarchs follow multiple flyways. The flyways used by eastern monarchs eventually merge into a single flyway in central Texas. Perhaps the most shocking aspect of this journey is the fact that every year a new migrating generation makes the trip to overwintering roosts that they have never visited before. Yet they are able to find the same flyways and arrive at the same spots as the generations before them.

While researchers know that migration timing is determined by seasonal changes, like day length and temperature, they are still investigating what directional aids monarchs use to return to the same overwintering sites every year. One convincing study suggests that the butterflies use the magnetic pull of the earth.

Since monarchs only travel during the day, they tend to find overnight roosting spots, typically in pine, fir and cedar trees. During cold fall evenings, monarchs will cluster in colonies in order to stay warm. Similar behavior can be observed when the monarchs are congregated within the oyamel forests.

Once the monarchs reach their destination, they settle in for the winter. As the season closes, and temperatures start to warm and days become longer, the monarchs become reproductive, breed and lay the next generation of remarkable monarch butterflies.

To learn more about how BASF is trying preserve this incredible creature, explore


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