Friday, September 30, 2011

The Incredible Journey of the Monarch Butterfly

The Monarch butterfly of North America

The white morph Monarch butterfly of Oahu, Hawaii

As I sit here on the lanai in Florida, I am watching the lovely and delicate Monarch butterflies as they flutter around the flowers and plants out back.    The Monarchs in my back yard are here all year round because of the warm Florida climate; however,  this is the big time for the northern Monarchs, because they are making their "incedible journey" from Canada to Mexico. 

Starting in August and on through October, the Monarch butterflies east of the Rocky Mountains, begin their journey south for the the winter.  Destination:  the sanctuaries of the Mariposa Monarca Biosphere Reserve in the pine-oak forests in the state of Michocan in Mexico.  The western  Monarchs winter in central and coastal California in Pacific Grove and Santa Cruz in santuaries there.

The life span of the Monarch butterfly is two months, so migration exceeds its normal lifespan.  The last generation of Monarchs of the summer enter into a non-reproductive phase known as diapause and may live seven or more months.  During diapause, Monarchs fly to one of the many overwintering sights.  The generation of Monarchs that overwinters does not reproduce until it leaves sometime in February or March.  The overwinter population east of the Rockies may reach as far as Texas and Oklahoma during the spring journey.  Second, third, an fourth generations return to their northern locations in the U.S. and Canada in the spring.

The Monarch is the only butterfly that goes both north and south like birds do, but no single Monarch makes the entire round trip.  It takes four generations of Monarchs to make the trip.

How do they manage to return to the same place over different generations is still under research.  It is believed by researchers that the flight patterns appear to be inherited based on a combination of the position of the sun in the sky.  Monarchs have a time-compensataed sun compass that depends upon the circadean clock based in their antennae.

Brand new resesarch shows that Monarchs can use earth's magnetic field for orientation when flying home.  The antennae contain cryptochrome which is a photoreceptor protein that is sensitive to the violet-blue part of the spectrum.  In the presence of the violet/blue light it can function as a chemical compass which tells the Monarch it is aligned with the earth's magneetic field, but is unable to tell the difference between the magnetic  north or south. 

Monarchs are one of the few insects capable of making trans-sea crossings.  Monarchs born in Bermuda usually remain there year round beecause of the mild climate.  Monarchs are found in the Canary Islands, the Azores and Madeira.  They are also found in India and Hawaii.  The beautiful white morph Monarch is  found on  Oahu in the Hawaiian Islands.   The N. American Monarch butterfly is closely related to the Jamaican Monarch and the S. American Monarch  south of the Amazon River

The Monarch butterflies, I think,  are the most beautiful of the N. American butterflies.  If you want to attract Monarch butterflies to your yard or garden, be sure to plant with the milkweed species.  This is what they feed on and will be sure to land and entertain and enchant you as you watch them.

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