Monarch Migration Update: September 13, 2000
Today's Report Includes:
Highlights Along the Migration Trail
Strong Cold Front Pushes Monarchs Through Iowa
"A spectacle of nature occurred late Monday afternoon in the skies over central Iowa. The day's temperature
had tied a record high at 97, and a cold front was passing through from the northwest to southeast. At approximately
4:30 p.m., migrating monarch butterflies could be seen in the sky floating on the wind, their shadows showing sharply
against the clouds above. As the wind picked up in intensity, monarchs could be seen flying high and quickly, floating
speedily on the wind, or being pushed to the east by the windy conditions.
See Dr.Woodward's website "Save the Monarch", with journal of daily observations.
09/11/00 Waterloo, IA (42.29 N, -92.20 W)
Will the Same Cold Front Trigger Migration in the East?
We asked Dr. Lincoln Brower for his thoughts about this apparently low numbers of monarchs. He replied: "It is a mystery to me....There have been virtually no migrants here in Virginia at all to date. However, we have not yet had a strong cold front push through. If we do not start seeing migrating monarchs by the end of this week, then we can begin really wondering."
Cold Fronts, Wind and Fall Monarch Migration
How is the flight behavior of monarchs affected by cold fronts? Generally, says Dr. Calvert, when winds are from the south, monarchs are flying low, and are the most visible to observers. When the winds shift to the north, monarchs move to high altitudes where the winds are stronger--but where the monarchs are less visible to observers.
"It's easy to see why monarchs come in on cold fronts," says Calvert. "It's like catching a bus going your way - in this case the ride is even free! Monarchs probably ride the layer of uplifted air associated with the advancing edge of these cold fronts. But that is not all they ride. They generally move with any wind that has a northerly component and may still be seen traveling days after the front has past. They may also migrate in not-so-strong southerly winds! In these cases, they are often found flying low to the ground and are very noticeable."
Peak Migration Now in Nebraska
The southernmost edge of the peak migration now appears to be in Nebraska, according to observers there. A flurry of reports arrived from that state beginning last Wednesday. Read these observers' comments, note the date of their sightings, and then check the Weather Map Archives to investigate how weather conditions affected the migration:
When Will Monarchs Reach the Sanctuaries? Revisiting Challenge Question #2
As you watch the migration move down your map, revisit your prediction--and let us know what you think!
Four Ways to Watch for Migrating Monarchs
The four observation methods described below include many helpful tips for making your fall migration-watching interesting and valuable. Included are descriptions from experts, and links to websites with examples.
How Many Monarchs in the Alfalfa Field?
Challenge Question #3
The monarchs now passing through the Midwestern states are moving through the U.S. "Corn Belt," so named because so much of the land is planted in corn. In fact, where there was once prairie, as much as 90% of the land is now planted with crops. Monarchs looking for nectar in this region sometimes find alfalfa fields in bloom--a good source of nectar.
Surrounded by miles of corn and soybean fields, the 40 acres of blooming alfalfa shown in these photos is a magnet for hungry butterflies. Alfalfa hay is used for milk cows, and farmers rarely allow alfalfa to bloom because the food value of the hay decreases when it's allowed to flower. On this fall day, the alfalfa was in full bloom and there was a butterfly every 8 feet--so many butterflies that the field itself appeared to be fluttering.
When Will the Migration Reach You?
Discussion of Challenge Question #1
Students in Ms. Dempsey's Second Grade Class in Framingham, MA, and in Mrs. Kloewer's 4th Period Science Class in York, NE agreed:
"We think that's moving pretty fast for some little creatures," said the Nebraska students.
Reminder: EARLY Symbolic Migration Deadline--October 2nd
Only 19 more butterfly-making days before the deadline. Don't be late! Butterflies received after the postmarked deadline cannot migrate!
How to Respond to Today's Monarch Challenge Questions:
IMPORTANT: Please answer ONLY ONE question in each e-mail message!
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