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Monarch Butterfly Migration Update: April 18, 2001

Today's Report Includes:

First Monarchs Spotted in the Carolinas, Tennessee and Virginia

To view both maps simultaneously, open two windows of your browser (Netscape, Internet Explorer, etc.)

This Year
April 18, 2001

Last Year
April 19, 2000

Since the surprising single sighting from Georgia last week, the migration map has filled in with additional sightings from scattered locations all the way from Texas to Virginia.Virginia? That's a long way from Mexico!

Challenge Question #22
"Assuming it flew from the sanctuaries in Mexico (19N, -100W), how many miles did the monarch spotted in Gloucester, Virginia (37.28 N, -76.33 W) fly? Measure distances "as the crow flies" (or in this case, the monarch!)."

Challenge Question #23
"If, instead of going to Virginia, that same monarch butterfly had flown the same distance DUE NORTH from Mexico where would it be? Give the name of the state, the nearest town, and the latitude."

(Clue: You already know the longitude would be -100 W, because we're assuming the fictitious butterfly flew due north.)

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

Spring Monarch Migration Routes:
Time to Revisit Your Predictions!

Is the migration traveling in the direction you predicted? Record the new states where monarchs have arrived on your Migration Route Prediction Chart:

NOT Seeing Many Monarchs? Send Us the News!
As we learned last week, this year's monarch population is very small. Therefore, ALL observations are critically important. If you're looking for monarchs and are NOT SEEING ANY, please let us know!

Report to our database as, "Monarch (OTHER observations)"

Here are examples of the type of observations that are valuable:

"The monarch activity here is definitely below what I have observed over the past 5 years. The egg counts and adult sightings continue to be low and the few eggs we've found have all disappeared within 24 hours, presumably to fire ant predation. There is also a small red mite on the plants in our field. Could these be predacious?"
Dr. Bill Stark, Clinton, MS

"Just a note to say that I have not seen another monarch after that first sighting, April 9th!! No eggs or caterpillars, either, on any milkweeds that I have checked. Strange year!!"
Dr. Gary Ross, Baton Rouge, LA

How FEW Monarchs in Mexico?
Discussion of Challenge Question #21

There were fewer than 30 million monarchs at the over-wintering sites this year, according to calculations by Mrs. Dempsey's 2nd Class at Charlotte Dunning School in Framingham, MA. Here are their calculations for each year since 1994/, based on an estimate of 13 million monarchs/hectare:


Estimated Number
of Monarchs




162, 630,000











"We are wondering if more monarchs died on the trip to Mexico," the students remarked. "Each year there are less and less and by next year there will probably be less again."

Population Dynamics
Studying Changes in Population Sizes

These students are asking the same questions scientists are! What caused the over-wintering population to be so small this year?

"Population dynamics" is the study of changes in the number and composition of individuals in a population, and the factors that influence those changes.

Next month, monarch biologists and the interested public are invited to attend the first Monarch Population Dynamics Meeting in Kansas. Dr. Chip Taylor of Monarch Watch says that the meeting is intended to summarize what is known--and what needs to be learned--about monarch population dynamics. The knowledge can be used to inform policy makers and to guide future research efforts.

"This meeting signals the start of a unique project - namely, to gain an understanding of the annual dynamics of a migratory species with a continental distribution," says Taylor.

Link to information: Monarch Population Dynamics Meeting

Student Worksheet
Analyzing Monarch Population Dynamics 2000-2001

You'll appreciate how difficult the scientists' work is by thinking through this challenging problem yourself!

List all the factors you can imagine that might cause low numbers at each stage of the monarch's annual cycle. Begin with last year's breeding season. What factors might have caused lower reproduction? What could have caused higher mortality? Do you think last fall's population was already smaller than normal before the migration began? Next consider the fall migration. Look back at last fall's migration news for reminders of causes of mortality during fall migration. Was last fall's migration particularly difficult? Finally, consider what you've learned about mortality at the over-wintering sites. (The population estimates were made in late December, so consider mortality causes only to that time.)

Students should maintain their own lists on the Student Worksheet, by adding a causal factor each time one comes to mind. As a class, make a brainstorming chart with three columns labeled, "Breeding Season," "Fall Migration" and "Over-wintering Season." Keep the chart on the wall for the rest of the migration season. Periodically, gather all of the ideas from the class and add them to the appropriate column.

After the Kansas meeting, we'll use the same format to summarize the scientific discussions and presentations.

Earth Day Next Week: Students Consider Helping Monarchs
Students in Mrs. Large's class at McFadden Elementary in Murfreesboro, TN were concerned after reading last week's report. "My class has been recycling aluminum cans this winter to earn money for an Earth Day project," wrote Mrs. Large. "We were going to adopt an acre of the rain forest or adopt an endangered animal. The students are all very concerned about the low numbers of monarchs this year. We were wondering if it is still possible to donate to the Monarch Conservation in Mexico or if you know of another way that we can contribute our money to the preservation of the Monarchs."

Contributions from students would be GREATLY appreciated at this critical time! The Monarch Butterfly Sanctuary Foundation continues to raise money to support work in Mexico. You can read about the project and how donations are used on the Web.

Field Work While You Wait
Monitoring Changes in Monarch Habitat

As you wait for the monarch migration to reach your home town, watch how monarch habitat changes BEFORE the butterflies arrive:

Please print this checklist and take it with you in the field. Predict when you'll see the first milkweed, nectar sources and monarchs. Then take regular notes about the changes as plants and their flowers become available to monarchs. This information is important even when you DON'T see butterflies. You can only see changes if you have observations which you can compare.

Is Monarch Habitat Ready for the Monarchs?
Latest Milkweed Map

How does the readiness of monarch habitat affect the pace of the migration? How will the availability of milkweed affect the reproduction of the next generation? These are critical questions. Please help find the answer! Keep a close eye on the sky for monarchs--and an eye underfoot for milkweed:

Please report the FIRST MILKWEED to Emerge This Spring!

Monarchs in the News
Write Your Own Newspaper Column

Tell your community that the monarchs are on their way! Offer to be a reporter for your local or school newspaper. One year, students at Cape Cod Lighthouse Charter School wrote their own weekly news column called "Nature Track" for their community newspaper. From February to June, the students captured highlights from Journey North News to include in their column. For suggestions for your weekly news reports, see their example:

Symbolic Monarchs Now on the Last Leg of Their Journey!
The symbolic butterflies have arrived! We will spend the rest of the month packing them up, and should have them in the mail to you no later than May 1st. We must mail all packages at once--otherwise, people worry that their butterflies are lost and write to us in concern. Therefore, we plan to have all butterflies mailed by this deadline, so:

Please Mark Your Calendar!
Homecoming for Symbolic Monarchs: May 11, 2001

How to Respond to Today's Monarch Challenge Questions:

IMPORTANT: Answer only ONE question in each e-mail message.

1. Address an e-mail message to:
2. In the Subject Line of your message write: Challenge Question #22 (or #23)
3. In the body of the EACH message, answer ONE of the questions above.

The Next Monarch Migration Update Will Be Posted on April 25, 2001

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