The spring migration of monarch butterflies from Mexico is one of nature's most dramatic migrations. Each spring, millions of monarch butterflies re-populate eastern North America after surviving the winter in the high mountains west of Mexico City. They flew up to 2,500 miles to get there last fall, and are spending the winter living off of the precious energy contained in their fat reserves.
This is the first in a series of reports about their wintering grounds in Mexico, leading up to the announcement of their departure sometime in March. At that time, you'll be invited to take part in an international science project with students and scientists across North America as we map the migration over the Internet.
Today's reports are produced by: 1) The Mexican research team studying at the wintering colonies this season. 2) An American family who visited the sanctuary last weekend. 3) Background information about monarch butterflies was prepared by Mrs. Savaiano's students at Barton Open School, Minneapolis, Minnesota.
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If you were looking for the ideal home how would you describe it? Monarch butterflies in search of a place to spend the winter in Mexico have very specific habitat requirements. They live only:
In Pine Forests At or Above 3,000 Meters Altitude
Their lives depend on the microclimatic conditions that occur in these places. While other spots are too hot or too cold, too wet or too dry, these forests are JUST RIGHT. But there are only nine places monarchs have found to spend the winter and they're all located west of Mexico City in Mexico's Transvolcanic Belt. These forests act as a thermal blanket and rain umbrella for the monarchs, providing the ideal temperature and moisture conditions that enable them to survive the winter.
See if you can find each of the known monarch sanctuaries on a map of Mexico:
Colony Name Location
Chincua 5 km north of Angangueo Campanario (Rosario) 3 km southeast of Angangueo Picacho 6 km south of Angangueo Chivati 15 km southwest of Angangueo El Pelon 8 km southeast of Zitacuaro Altamirano 20 km north of El Oro San Andres 18 km northwest of Ciudad Hidalgo Herrada 30 km southwest of Toluca Las Palamas 28 km south of Toluca
(If you need help finding this region: Angangueo and Zitacuaro are about 125 km west, northwest of Mexico City. Toluca is 45 km west of Mexico City and El Oro and Ciudad Hidalgo are 30km north and 30 km west of Angangueo respectively.)
How large is this region? Using your map, figure its area in square kilometers. Next, using a map of your state or province, draw an area of the same size centered around your home town. Does this seem like a large or small area to hold all of eastern North America's butterflies?
Why do you think each of the habitat requirements listed below is important to the monarchs?
1) forests 2) high altitude
CHALLENGE QUESTION
What is a microclimate?
Write the best definition you can and send it to us at:
SUGGESTED RESOURCES International Wildlife, November-December, 1987 National Geographic, August 1976.
Internet: Gopher to: schoolnet.carleton.ca Pathway: /SchoolNet Gopher/The Virtual School.../Science & Engineering Floor.../Biology Room/ Gopher/ Canadian Museum of Nature Monarch Butterfly Net
Recommended by teacher Rod Murray of Ottawa who says, " Notice that the gopher is fully bilingual and is a great place for kids to explore, especially if they are taking french in school!
Coming Next Week:
One million one, one million two, one million three.... Imagine counting all the butterflies from the United States and Canada! Next week scientist Bill Calvert and colleagues will report on their recent visit to Mexico. Their job: Estimate the number of monarchs over-wintering in Mexico this season. They'll provide the preliminary results of their attempt to estimate the total population size.
Copyright 1995, Journey North. All Rights Reserved.