Sep 20 2008
As I write this, eastern monarch butterflies are migrating south to Mexico, a journey of 2,500 miles for those who hatched in Canada.
What makes such a small, delicate insect travel so far?
Insects have a variety of strategies for surviving the winter. Some overwinter as eggs, others as larvae underwater, in cracks or in mud. Some adults hibernate and just a few – including monarch butterflies – migrate.
Unlike their spring and summer ancestors, the monarchs who emerge from chrysalids in the fall don’t breed. Though they look like adults, the shorter days and cooler nights delay their sexual maturity. Instead, they migrate to twelve mountaintop sites in Mexico. Then in March they travel a short distance north and breed. Succeeding generations live 2-6 weeks and also fly north so that several generations later our first spring monarchs arrive in late April.
How did people figure out that monarch butterflies migrate?
It took over 40 years of tagging and tracking monarchs before Dr. Fred Urquhart found their wintering site in 1976. Even then it was kept secret for a while because the scarcity of sites makes the population vulnerable. Nowadays the wintering sites are eco-tourism destinations where visitors can observe millions of butterflies in the Oyamel fir trees. You can also participate in tagging and tracking programs here at home.
My friend Marcy Cunkelman has been tagging monarchs for many years. Similar to bird banding, monarch tags are uniquely coded stickers applied to the butterflies’ wings. In order to collect monarchs Marcy designed her garden to be attractive to butterflies. In her photo above you can see a cluster of four of them on her butterfly bush. The one on the left is showing its tag.
Marcy’s monarchs have traveled far. In 2003 she learned that one of her butterflies was recovered in Mexico.
p.s. I saw a lot of monarchs migrating on the Sept 14 before Hurricane Ike came to western PA, then none until today. I think a lot of butterflies died during the wind storm.
(Marcy Cunkelman also teaches hands-on programs on monarchs and butterfly gardening.)