Monarch Migration


What comes to mind when you hear the word migration? How about monarch butterflies? Every October, monarch butterflies leave their homes in Canada and parts of the northern United States to head for warmer weather in Mexico and southern California. Once the butterflies arrive at their destination, they overwinter until they return to their northern homes in spring. While in Mexico and California, the monarchs will gather together in eucalyptus groves. They usually return to the same groves their ancestors gathered in the past.

This cycle is like clockwork, but can be affected by the weather, particularly the temperature. Since monarchs cannot fly if the temperature drops below 55 degrees Fahrenheit, they work against the clock to make sure they have migrated before a drastic temperature drop. As current weather patterns continue to change, and temperature and weather greatly fluctuate, some monarch populations are slow to migrate. This can ultimately lead to greater causalities when there is a sudden drop in temperature.

The monarch cycle comes to an end in the spring when the monarchs who migrated in fall, return north. Upon returning north, they will lay eggs and begin the next generation. This return trip must occur to complete the cycle because monarch larvae feed on milkweed which does not grown in southern regions. Therefore, without the migratory patterns of monarch butterflies, the population wouldn't survive. 

Jeni Vogel, Associate Director of Preschool & Camp