Monarch Migration Update: May 3, 2000
Today's Report Includes:
Highlights From the Migration Trail
No sooner had we made this week's migration map, than this exciting news arrived:
How Far North Do Mexican Monarchs Travel?
Your map probably now shows how far the monarchs from Mexico will travel this year. (Notice that the leading edge of the migration has reached about 41 N, all across the monarch's range.) As this generation dies, we expect to see a drop in sightings over the next weeks. After all, these butterflies have been alive for a long, long time! That's why we asked last week...
How Long Have These Monarchs Been Alive?
Discussion of Challenge Question #36
"Assume a butterfly emerged as an adult last August 26 in Maine. For how many days has the butterfly been alive as of April 26, 2000? For how many weeks?"
"Our class answer is that the monarch has been alive for 245 days, or 35 weeks," wrote Miss Bailey from Citrus Elementary School Vero Beach, FL. That's 8 months!
"We had fun with this one," she said. "Our second and third graders tried to add the number of days in each month to figure out how long the monarch had been alive. Then they tried to divide their answer by seven to get the number of weeks (that was more difficult, since they're still learning how to divide). They worked independently in their journals. Then they turned in their work. After that we worked it out together on the board. I told the kids we would submit the answers closest to what we worked out together. All the kids did a great job!"
Story of a Life's Journey
If a monarch butterfly could talk, just think of the stories it could tell! Imagine a butterfly whose life began 8 months ago in the north, and write its life story:
(To respond to this question, please follow the instructions below.)
Next Generation Soon on Its Way!
A New Way to Look at Your Migration Map
Last week we suggested a new way to view your map. If you assume that:
On the right is the new map! It shows when and where we can expect the next generation of monarchs to emerge. Note how the dates of the legends changed:
Discussion of Challenge Question #35
Using the same assumptions, Challenge Question #35 asked, "When might we expect monarchs to emerge in Arkansas?"
Mrs. Dempsey's second grade class in Framingham, MA considered this question and decided they, "expect the monarchs in Arkansas to emerge on April 21." (email@example.com)
What a good estimate! If you look at Arkansas on the migration map, you'll see many light yellow dots. The legend says this means the first monarchs arrived there between Mar 15 and Mar 28. According to the new legend above, the first NEW monarchs to emerge should be between Apr. 16 and Apr. 29. So the April 21st estimate is right on.
And here's proof from Arkansas! Jim Edson's first monarch emerged on April 27th. "I released my first monarch that came from an egg that was laid March 27th," he said. "She was raised in a screened box that was kept outside." (firstname.lastname@example.org) It took this monarch 31 days to develop.
Are the Monarchs Ahead of Their Milkweed?
Discussion of Challenge Question #33
Mrs. Dempsey's class also did a great job summarizing the milkweed observations reported from each state in our April 26th update. They noted:
As the students point out, many people have been seeing their first monarchs JUST as the milkweed is emerging.
Now remember: When milkweed emerges it's only a tiny plant. It takes time for the plant to grow and for its first
leaves to unfold. And when the eggs hatch only 3-5 days after they are laid, very hunger caterpillars will emerge--ready
to eat the leaves. If you've ever raised a monarch, you know how much milkweed one larva can eat!
Which Grows Faster, a Monarch or a Milkweed Plant?
Here's an experiment you can try to get a better idea of how much milkweed an early monarch might need in the spring:
1) Watch for a milkweed plant to emerge this spring.
2) When its first leaves appear, measure the surface area of each leaf. (To do this, make a grid by photocopying graph paper onto a clear transparency. You'll be able to see through the grid and count the surface area on the leaf.)
3) On a sheet of paper, make two columns like this:
4) As the plant grows, record the amount of milkweed that's available each day.
5) Next capture a monarch larva, and measure how much milkweed the larva eats in the 9-14 days it takes to go from egg to chrysalis.
6) Then summarize your results:
Monarch Larval Monitoring Project
In order to monitor monarch populations, Dr. Karen Oberhauser and Michelle Prysby are looking for volunteers to collect long-term data on larval populations and milkweed habitat. Their overall goal is to learn how population densities fluctuate throughout the monarch breeding season in North America.
This is important information, because when conservation issues arise (such as the impact of Bt corn on monarchs), we see how little is really known about healthy monarch populations. If you'd like to help with this study, please see the Monarch Lab website for details.
Please Note: We will continue to track the monarch migration until the butterflies
reach the end of the road in late June. However, we're asking for your evaluation of our program now, before the
end-of-the-school-year rush. Thank you!
The Next Monarch Migration Update Will Be Posted on May 10, 2000.
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