Monarch Butterfly Migration Update: August 27, 2004
Today’s Update Includes
- The Migration is Underway! Mapping Begins Sept. 3
- Welcome Back to School: Learning vs. Instinct
- Learning Takes Time But...
- Try This! Monarchs Are Born Knowing How to...
- Observers Report Few Summer Monarchs
- Dr. Karen Oberhauser’s Study Indicates Low Population
- Making Sense of the Data: Student Worksheet
- Challenge Question #1: Any Correlations with Mexico?
- Helpful Reminder: Thinking Like a Scientist
- Why So Few Monarchs in the Upper Midwest?
- Challenge Questions: A Central Tool for Student Learning
- Monarchs Traveling Through Your Hometown? Photos Please!
The Migration is Underway! Mapping Begins Sept. 3
The monarch migration to Mexico is underway! First reports of southbound monarchs are now coming in, and butterflies are beginning to gather at their overnight roosts. Watch for migration maps in each weekly update beginning Friday, September 3.
| Migratory monarchs resting last week at roosts in Minnesota and Iowa | ||
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| Fairbault, MN | Pocahontas, IA | Waverly, IA |
| Courtesty of Paul Cherubini | ||
Welcome Back to School: Learning vs. Instinct
Our lives take a turn in the fall. Across the north, summer's long days shorten rapidly and temperatures drop. Meanwhile, millions of children return to school. Their year will be spent learning skills needed during the long human life span.
At the same time, a magical event takes place in the animal world. Perhaps traveling over your own head right now--or clustered by the hundreds in a nearby tree--the annual monarch butterfly migration to Mexico is underway. It's such an unlikely story! As if autumn leaves could arrest their fall, point southward, and float all the way to Mexico.
The butterflies are born knowing everything they need to survive, so we look on with wonder:
- How do the monarchs know when to go to Mexico?
- How do they know which direction to fly?
- And how do they know when they have found their destination--a small speck on the planet where none has ever been before?
Travel with the monarchs this fall as we explore questions like these. In the weeks ahead, we'll see what scientists know about these mysteries, and how much more there is to learn.
| Fueling up for the long flight to Mexico | The over-wintering Region in Mexico | Monarchs in flight at the sanctuaries |
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| Elizabeth Howard | NASA | Dr. Lincoln Brower, Sweet Briar College |
Learning Takes Time But...
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| Dr. Oberhauser has been learning about monarchs for over 20 years! |
An “instinct” is an inborn pattern of behavior. It is something an animal can do without having to learn.
“Unlike humans, insects don't have to learn much,” says Dr. Karen Oberhauser. “They are genetically programmed to do things like fly, find food, and migrate (in the case of monarchs). In some ways, this sounds like a great thing. However, there isn't as much flexibility in behavior for organisms that depend on instinct. We need to learn how to talk, walk, read, etc, but think of the flexibility we have in determining what we do with our lives. Insects don't have that.”
Try This! Monarchs Are Born Knowing How to...
As you learn about monarchs, keep a list of everything monarchs are born knowing how to do. For fun, compare the age at which humans learn to do the same things. Record all of your examples on this chart.
Observers Report Few Summer Monarchs
Throughout this summer’s breeding season, from May through August, comments like these have been common:
Ontario--For the first time, I was without success this summer in locating a single monarch larva despite a bumper crop of milkweed.
Pennsylvania--We have not seen any monarchs this year. What happened?
Connecticut--I have been searching in fields in Connecticut but I have seen no caterpillars this year.
Missouri--This year we have not been able to find any caterpillars. We usually have so many of them this time of year. Beginning a new school year is just not the same without Monarch butterflies!
With summer reproduction apparently low, fall reproduction in the southern states may be important to rebuilding the population. Watch for information about this in our September 3 update.
Dr. Karen Oberhauser’s Study Indicates Low Population
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| Monarch Reproduction Low for 3rd Year in Upper Midwest |
“There is a disturbing indication that the population is going down,” says Dr. Karen Oberhauser, upon reviewing data collected this summer in the Upper Midwest. During the breeding season, hundreds of volunteers participate in a study she coordinates called “The Monarch Larva Monitoring Project.” The volunteers count the number of milkweed plants that bear monarch eggs and caterpillars.
In the Upper Midwest this year, monarchs were present on fewer than 5% of the milkweed plants monitored. This compares to monarch presence on a high of over 25% of the milkweed plants counted in 1997, and an annual average of 13%. For the third year in a row, the population is well below average. (See chart)
Making Sense of the Data: Student Worksheet
Use this worksheet to help students analyze the monarch data collected in the Upper Midwest this summer.
Ultimately, scientists need to find accurate ways to measure the monarch population. They want to know whether it is stable. In the winter, Mexican scientists estimate the numbers of monarchs over-wintering in Mexico. Let’s compare the breeding season data collected by Dr. Oberhauser to the over-wintering data from Mexico. Do you see any correlations?
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| Monarch Reproduction in Upper Midwest | Over-wintering Population in Mexico |
Challenge Question #1
“In what ways are the charts similar? In what ways are they different? In your answer, give at least one reason why it is too early to draw conclusions from these sets of data.”
(To respond to this question, please follow the instructions below.)
Helpful Reminders: Thinking Like Scientists
Scientists look for patterns or relationships that might tell them something significant. They use their imaginations and think logically about new information. They relate it to what they already know and to other findings. They think about how findings connect to larger ideas. Then they make an overall statement or explanation. Scientists base their explanations on evidence. Scientists do not jump to conclusions. They are very careful not to draw conclusions that the data do not support. Scientists are "healthy skeptics." They continually question their own and others' assumptions, data, investigation designs, and results.
Why the Low Numbers in the Upper Midwest?
Dr. Oberhauser says she is concerned about the data because she can only speculate about the causes for the decline. Scientists do not yet understand how and why monarch populations vary in time and space. “It’s kind of a complicated problem because there’s not one smoking gun,” Dr. Oberhauser says. Many factors can affect the size of the population. Research has not yet shown clear links, but some possible causes for the reduced numbers are:
Challenge Questions: A Central Tool for Student Learning
Journey North provides "Challenge Questions" in each weekly monarch update. Challenge Questions model the thinking/questioning process that scientists use in their work. For more information and suggested classroom use see:
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 About Challenge Questions Video Clip |
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Monarchs Traveling Through Your Hometown? Photos Please!
Grab your digital camera the next time you go out into the field. We would love to receive photos from your unique place on the monarch migration pathway. Photos of monarchs fueling at your garden or resting at an overnight roost would be especially exciting to receive. Thank you!
How to Respond to Today's Challenge Question:
1.
Address an e-mail message to: jn-challenge-monarch@learner.org
2. In the Subject Line of the message write: Challenge Question #1
3. In the body of the message, answer the question above.
The Next Monarch Migration Update Will Be Posted on September 3, 2004.
Copyright
2004 Journey North. All Rights Reserved.
Please send all questions, comments, and suggestions to jn-help@learner.org
