Monarch Butterflies

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How Do Monarchs Respond to Hurricanes and Other Storms?
By Dr. Bill Calvert

September 10, 2010

As Hurricane Earl approached the coast of Maine last week, a friend saw how the monarch caterpillars he was watching responded. The monarchs had been feeding on milkweed but—before the hurricane arrived—they vacated the leaves and presumably buried themselves in the leaf litter. After the storm had passed, the monarchs reappeared on the plants and resumed feeding.

A short distance away, butterflies that had been flying and nectaring in a flower garden disappeared before the same storm.

The weather was extremely calm before the storm. "It was like everything got quiet," said a friend. The lobstermen brought their boats in, all the eiders came in close to shore, and no butterflies could be seen nectaring.

Scientists have made similar observations in conjunction with other hurricanes. At the Florida Museum of Natural History, butterflies hid in tree hollows and under rocks a few hours before the arrival of Hurricane Jeanne in September, 2004.

When a thunderstorm threatens migrating monarchs, I have seen them stop flying and descend to roosting sites. Their descent is often impressive and dramatic – a chaotic swirling action during the descent and milling chaos while forming their clusters. Thousands of individuals may be involved. This happened one afternoon near Linares, Mexico when a thunderstorm threatened. A large group of migrating monarchs spiraled down from a thousand feet elevation to form a huge roost.

There is a great deal of observational evidence that many types of animals can sense the coming of a storm and take appropriate action.

Dogs in particular are sensitive to approaching storms. Many will cower at your feet and shiver with fright in response to thunder and lightning. Many follow you around and get under your feet well before the storm has presented itself.

How can they tell when a storm is approaching? Some animals appear to respond before there is any physical evidence that a storm is coming. They respond before the sky is stormy and when the winds are calm. Scientist think that a change in pressure is involved. Evidently, many animal species can sense falling air pressure and then change their behavior accordingly.

For further information about this topic you might want of look at the book, Ready, Set...Wait! What Animals Do Before a Hurricane by Patti R. Zelch.

Read More:

• Hurricanes: A Fall Migration Hazard: It was lucky timing for monarchs when a strong hurricane hit in Texas in September 2008. (See story.)
• Tagged monarch blown by Hurricane Katrina? A tagged monarch was evidently blown 165 miles in the wrong direction by Hurricane Katrina, northwest from Ohio to Ontario. (See story.)
• Monarchs in England after gale winds: More than 170 monarchs appeared on the south coast of England in the fall of 1995. Weather backtracking suggests the monarchs could have been carried across the Atlantic Ocean by the wind for four days. (See story.)
• Can a monarch fly across Atlantic Ocean? (See lesson.)