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Monarch Migration Update: November 8, 2002

Today's Report Includes:

Field Notes from the Monarch Sanctuary Region in Mexico

Monarchs Have Arrived by the Thousands!
The news we ve all been waiting for is here: Thousands of monarchs were discovered covering the trees at El Cerrito, the hillside in Angangueo, on November 1. German Medina suddenly found ten trees covered with monarchs that day, containing perhaps 10,000 butterflies each (it s very difficult to even estimate!).

Here are his daily counts:

  • Nov. 1: About 10 trees were covered with butterflies (10,000 each?)
  • Nov. 2: Same as the day before.
  • Nov. 3: Around 30 trees were completely covered
  • Nov. 4: About 35 trees covered with monarchs
  • Nov. 5: Only 25 trees covered (some evidently moved on to sanctuaries?)
  • Nov. 6: Suddenly only 5 trees covered (and not as many as at first)

There were so many butterflies in each tree, German was overwhelmed at the thought of counting them. He said, On November 3, when such a quantity had arrived, as I approached them they looked as if to ask, 'Now German, would you dare to count us one by one?'"

Here are this week's observations, in both Spanish and English:

As you may recall, last week only single butterflies had been seen at the 4 sites which German has been monitoring daily since September 14. Did the monarchs arrive as suddenly as German s records suggest? Or, did he only find them suddenly? Remember: We must always take into account what could be occurring that we simply don't see. We ll have more information in our final migration update.

The Finish Line
The Mountains of Mexico's Transvolcanic Belt.

Like Finding a Needle in a Haystack?

The area in red measures over 9 million square kilometers.

Stop and think for a minute. The over-wintering sites are a tiny speck on the planet. This map shows the HUGE area in North America that monarchs migrate across on their way to the sanctuaries.

The area in red measures over 9 million square kilometers! In contrast, the sanctuaries are clustered within a region that measures only 800 kilometers square. This means that the monarchs find an area that is 11,000 times smaller than the area the migration crosses. Finding a needle in a haystack almost sounds easy in comparison! The monarchs certainly seem to know where they re going, don t they?

Try This! Challenge Question #16
Calculate the area of a standard football field, then answer this question:

Challenge Question #16:
Finding the Mexican sanctuaries in the North American continent is like finding a _____ on a football field. (Fill in the blank with something to scale. That is, name an object that is 11,000 times smaller than a football field.)

Here are the dimensions of a football field:

  • Length of field: 120 yards (including 10 yards of end zone at each end)
  • Width of field: 53 1/3 yards

(To respond to this question, please follow the instructions below.)

¿Cuántos por minuto?
Discussion of Challenge Question #14

From northern Mexico last week, Señora Treviño wrote about an incredible passage of monarchs seen on October 25: Mi nieto y Yo contamos las que pasaron por la casa y contamos ¡10,014 mariposas! en 35 minutos.

We asked, How many monarchs per minute did Señora Treviño and her grandson see?

Mrs. McCabe's students at Trinity School in Midland, Texas think they saw, about 286 mariposas per minute. We divided 10,014 mariposas by 35 minutes. We got 286.11428 and then we rounded our answer to 286. Amazing! Imagine how many butterflies passed per hour at that rate. (Better yet, do the calculations.)

How Far Across Mexico?

Discussion of Challenge Question #15

Since most of North America s monarchs are now crossing northern Mexico, we asked last week, How far do the monarchs travel across Mexico to reach the sanctuaries?

Writing from his homeschool in Arras, France (where his family is visiting this year) lucky Jonathan Koch wrote, The monarchs travel about 572.75 miles (920.75 km) as the crow flies from Del Rio, Texas to Angangueo, Michoacan, Mexico. This is the distance from Arras to Klagenfurt, Austia.

This is quite close to the answer we calculated using the web-based online distance calculator. We entered the coordinates for Del Rio and Angangueo and got these results: 760 miles (1,223 km). Try measuring the distance on a map, or using the online calculator, and see what you get. Either way, it certainly is a very long distance for butterflies to fly!

FINAL Migration Update Coming November 22
There will be no update next week due to a scheduling conflict. (The monarchs reached the sanctuaries much later than expected this year!)

Two weeks from today, we will post a brief update to summarize arrival news from Mexico. We will also outline plans for next spring s Journey North. (Weekly Journey North updates will begin in February.)

How to Respond to Today's Challenge Question

1. Address an e-mail message to:
2. In the Subject Line write: Challenge Question #16
3. In the body of the message, answer the question above.

The Next Monarch Migration Update Will Be Posted on November 22, 2002.


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