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Monarch Migration Update: September 8, 1999

Today's Report Includes:

Welcome to Journey South's Migration Season
The monarch migration takes place without a single sound--all the way to Mexico--but it creates a great stir of excitement in the hearts and voices of people who witness it. Over the next weeks, we'll forward highlights of this fall's migration, as reported from people along the monarchs' path. Please send your own observations and help track the monarch's trip to Mexico.

Latest Migration Map

Monarch Migration Routes

Mexican Monarch Sanctuaries

When Will the Monarchs Reach Mexico?
Students in the Mexican monarch sanctuary region are waiting for the monarchs. They'll watch the skies and send the news when the first monarchs are spotted--and when the monarchs are flooding into town. How long do you think it will take the monarchs to reach the end of the long migration trail?

Challenge Question #1
"When do you predict students in Angangueo, Michoacan, Mexico (19N, -100W) will report the first big wave of monarchs arriving at the over-wintering sites? (Give the exact date you think we'll receive their report and tell us how you calculated your answer.)"

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

Migration Now Strong in North Central U. S. States
Monarch biologist Lincoln Brower visited Journey North headquarters in Minnesota last weekend and found the migration in full swing. A cold front had moved through the region on Saturday night, and the cool fall-like air sent many monarchs on their way. (Temperatures in the Dakotas dropped from the 90's to 50's when the front moved through!)

Cold from Brings Cool Fall Air to North Central States

Friday, Sept. 3

Saturday, Sept. 4

Sunday, Sept. 5

The flurry of migration reports from Minnesota, Wisconsin, Iowa, Illinois and Michigan suggest that butterflies are now pouring out of the north:

Dr. Lincoln Brower: Field Studies You Can Do at Roost Sites
"There's so much yet to be learned at the temporary roosts (or "bivouacs") that monarchs use during migration.

We asked, "How would a person study a site? What would you do?"

"I'd pull up a chair, grab a pair of binoculars and just sit and watch! I'd try to stay hour after hour, day after day--as long as the monarchs were there. People can contribute important observations by going with an open mind and documenting what they see. Science is often done with pre-conceived ideas, and so scientists can get hung up on their own theories, and forget to ask 'What IS going on here?' Here are some of the questions I'd try to answer:
  • What time of day do the monarchs arrive?
  • Do they gather up in the sky and all drop down at once?
  • Or do they arrive gradually?
  • How do they interact as the roost site forms?
  • How tall are the trees? Do they afford protection from the wind?
  • Does the roost-size vary, depending on the direction of the wind?
  • Are they active at night? Can you tell when they go to sleep?
  • How long do individuals stay? (To test, tag and release. See: Mark, Release, Recapture)
  • When do they depart? Do they all take off the next morning? Or on the next clear day? Do they gather and wait for the next front to arrive?
  • We know they fatten up as they fly southward, so nectar is important. Can you spot good nectar areas nearby? How do numbers of monarchs nectaring compare to numbers at the roost?

Please send your observations to Journey South and help document this interesting aspect of monarch migratory behavior! (jnorth@learner.org)

Monarchs Resting at Roost in MN

Crossing to Safety
At a Minnesota prairie with Dr. Brower, we saw a very fresh monarch whose left forewing was torn off at the tip. He suspected the butterfly had been hit by a car. "Cars are a significant cause of monarch mortality during migration. I bet natural selection is selecting for butterflies that fly higher than the traffic," he noted.

Look at a road map and imagine how many roads a monarch must cross when it flies to Mexico! Then see if you can answer these questions:

Challenge Question #2
"For a successful migration, how many times must a monarch cross a road when traveling from your hometown to Angangeuo, Mexico (19N, -100W)? (Assume an average of 2 north/south roads per mile.)"

Challenge Question #3
"Define natural selection and explain what you think Dr. Brower means by his statement."

(To respond to these questions, please follow the instructions below.)

Sad but true, counting the number of dead butterflies along the roadside when you travel is one way to measure the pace of migration. You may include the number road-killed butterflies per mile when reporting migration sightings.

Reminders: Symbolic Migration Deadline is October 8, 1999
All migrating symbolic monarchs must be on their way no later than October 8th. Don't forget this postmark deadline. For more information see: Send a Monarch to Mexico

Spring Teacher Trip to Mexican Monarch Sanctuaries
Travel with Dr. Bill Calvert to the monarch wintering sanctuaries in Mexico next March 11-18, 1999. Cost: $950 plus airfare to Mexico City. For details write to Dr. Calvert directly at: wcalvert@bga.com
How to Respond to Today's Monarch Challenge Questions

IMPORTANT: Please answer ONLY ONE question in each e-mail message!

1. Address an e-mail message to: jn-challenge-monarch@learner.org
2. In the Subject Line of your message write: Challenge Question #1 (or 2 or #3).
3. In the body of EACH message, answer ONE of the questions above.

The Next Monarch Migration Update Will be Posted on September 15, 1999

Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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