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Monarch Migration Update: September 6, 2002

Today's Report Includes:

Highlights Along the Migration Trail

Almost 100 people reporting migration sightings during the last week, but people described the migration so far as lackluster and are hoping it’s just late. This poetic comment from northern Minnesota describes its slow pace best: “Fat, fresh, monarchs lazily floating southward in onesies, twosies, threesies. No large roostings or mass flights.”

The first strong cold front of the season did push through on Monday, and several people noted their first nighttime roosts in the north. In states across the south, first monarchs are now appearing, after being absent in most places all summer. Scientists think these monarchs produce a final, fall generation there. This is something learned recently, thanks to volunteer observers compiling their observations.

  • For more migration highlights of the week, click on the migration map above to read observers’ comments.

Southbound With the Butterflies:
Orioles Take Off for the Tropics

Photo Chandler Robbins
Monarch butterflies aren’t the only species filling the skies this fall. After this week’s cold front arrived, Julie Brophy’s orioles took off for Central America. All but one left in a single day! Scientists think songbirds can detect barometric pressure. After cold fronts move through, the barometer rises, and songbirds know it’s a good time to go. Rising barometric pressure means a high pressure cell is coming, with clear skies and calm winds. Do you suppose monarchs are able to anticipate weather changes too? Here are Julie’s careful weather and songbird observations:

Contributed by Julie Brophy, Journey North
“My orioles take off early every September with the first strong cold front. Like clockwork, this year was no exception. All last week, I watched the Orioles and the weather carefully for signs that they might be getting ready to leave. But strong winds blew from the south, and their behavior was routine all week...until Monday…”

How Iowa Students are Monitoring the Migration
Thanks to students at Sheandoah Middle School in Sheandoah, IA, for their great example of how you can watch and document monarch migration where you live:

“We live in the southwest corner of the state of Iowa. Every morning at 9:40 AM we walk outside our school building down by a ditch that has some milkweed in it. We stand outside for four minutes. We started our log on August 29th and didn't see any monarchs. September 4th we saw four monarchs and captured one monarch caterpillar. Today, September 5th we saw ten monarchs. We will keep you posted.” Alex, Ben and Hanna

Discussion of Challenge Question #1
In last week’s story, monarch tagger Tom Murphy noticed monarchs gathering on the same side of his tent whenever caught inside. Challenge Question #1 asked, "On which side of the tent do you think the monarchs gather? Why?"

It was fun to receive your answers all week and see the good reasoning taking place. On which side of the tent did the students think the monarchs gathered, and why?

On the west side:
“Because the monarch butterflies gathered there from the previous evening for warmth, and have stayed there all night.”

On the east side:
“So they'll catch the sun's rays right away in the morning, and the rays will start warming their bodies after a chilly night.

On the south side:
“Because that is the direction they need to go to get to Mexico.”

Thanks to students in these schools for contributing their answers!

  • Miss Strobel's Class, Rockford Public Schools, Rockford, MI;
  • Ms. Grindo’s Grade 3 class, Minor Elementary Lilburn, GA;
  • Poth Elementary Students, Poth, TX;
  • Ms. McCabe’s class, Trinity School, Midland, TX;
  • Joshua, Grade 6, Rogers Middle School, Rogers, MN

At the Murphy’s, the monarchs gathered on the south side, ready to head to Mexico! Amazingly, the doors on the cold frame are on the east and west ends, but the butterflies don’t fly out the open doors to escape. During fall migration, people often see monarchs so intent on flying southward that they’ll nearly hit a building in their path. They fly straight up and over, rather than around, the building at the last second. Monarchs are serious about heading straight south!

Tom showing open doors on the east and west ends of the cold frame
Tent with monarchs
Gathering on the south side, ready to go to Mexico!

You’re the Scientist: Thinking Through Research Design
As a class, discuss how you might investigate these questions and/or answer them in your science journal. Better yet, organize your colleagues and conduct your own research!
  • Do you think monarchs would gather on exactly the same side of a tent in Waterville, Maine as in Winnipeg, Manitoba? Find each place on a map and explain why.
  • If it were spring, do you think monarchs would be attracted to a certain side of the tent? Which side?
  • How about during the breeding season, in mid-summer?

How Do They Know Which Way to Fly?
Exciting new research suggests that monarch butterflies use the sun as their clock and compass during migration. In a scientific paper just published, biologists Barrie Frost and Henrik Mouristen described the research they conducted during last fall’s migration.

You’ll find a link to a video clip of this clever experiment on Dr. Frost’s website, Animal Navigation:

Here’s what the biologists did: They collected monarchs, divided them into three groups, and put them in their lab under artificial light. The control group received light during normal daylight hours (for 12 hours, from 7 am to 7 pm). But the two test groups were “clock-shifted,” meaning they were exposed to 12 hours of light but not during normal daylight hours. One group was “clock-shifted” 6 hours early (receiving light from 1 am to 1 pm). The other group was “clock-shifted” 6 hours late (receiving light from 1 pm to 1 am).

Before reading further, think what would happen if your biological clock were shifted by 6 hours:

Challenge Question #2:
“If someone changed your biological clock ahead by 6 hours, what would be happening at school if you arrived 6 hours early? If your biological clock were behind by 6 hours, what would be taking place if you arrived at school 6 hours late?”

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

Try This! Follow The Sun
It’s hard to visualize this experiment without a model, so try this activity. All you need is a sunny day, several trips outside, and a plastic dome. First find the direction to Mexico from your hometown. Draw an arrow on the dome to show the direction of flight to Mexico. Then, using the model, record how the sun sweeps across the sky during the day.

(Just think, monarchs know all of this by instinct! So even if you find this complicated, you’ll appreciate the challenges monarchs face when using the sun as a clock and compass! )

Link to: Follow the Sun

Reminder: Symbolic Migration Deadline--October 11
Only 36 more butterfly-making days before the deadline. Don't be late! Butterflies received after the postmarked deadline cannot migrate!
Please Report Your Sightings!
We can't track migration without your help. Please come to the web and share your observations.

How to Respond to Today's Challenge Question

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

The Next Monarch Migration Update Will Be Posted on September 13, 2002.


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