Monarch Butterfly Migration Update: April 22, 1997

Colin Maher, Macalester College

A very interesting sighting arrived from a 12 year old girl on Cape Cod, MA. In each of the 4 seasons we have tracked spring monarch migration, the first Massachusetts sighting has occurred after May 16th. Be sure to read the discussion below about this students' unusually early observation.

• Link to Today's Migration Data

Challenge Question # 12
"Many monarchs were sighted on April 20th. Can you name one possible reason for this which has nothing to do with monarch butterfly behavior?"

To respond to this question, please follow the instructions at the end of this report.

Also in this report:

* Monarch biologist Dr. Lincoln Brower is concerned that an early spring migration indicates the butterflies left Mexico early. He interprets this as a possible sign that, "We are witnessing the unraveling of the microclimate in Mexico due to the relentless thinning of the Oyamel forests."

• Link to Dr. Brower's Comments

* Mexican field biologist Benigno Salazar reports 90% of the monarchs had left Mexican sanctuaries as of April 2nd.

• Link to Mensaje Ultimo de Benigno Salazar
• Link to Final Message From Benigno Salazar

How to REPORT:
When you see your first monarch this spring, please let us know! On the left-hand side of this page you'll see an owl button. Simply press the button and a FIELD DATA FORM will appear. If you have any trouble using this system, send a message to our feedback form We'd be happy to help you!

What to Report: Click Here for Field Data Checklist

Watch Out for Imposters!
As you search for the most wanted butterfly this spring, beware of an impostor! There's another butterfly out there that's disguised as a monarch. (Don't worry, it's not armed and dangerous to predators as monarchs are.) Viceroy butterflies look exactly like monarchs to the untrained observer. In fact, viceroys "mimic" monarchs in appearance as a strategy against predation.

USFWS

As we track the monarch butterfly migration each spring, we must always be concerned about accurate identification. How can we be sure people are not reporting the first viceroy they see? Pull out your field guide to butterflies and make sure you can tell the difference between monarchs and viceroys. Then place a call to your local nature center and see if they can help you answer these questions:

Challenge Question # 13

1. "When are viceroys first seen in the spring where you live?
2. At what stage of their life cycle do viceroys overwinter, as an egg, larva or adult?
3. Where do viceroy butterflies spend the winter?"

To respond to this question, please follow the instructions at the end of this report.

Karen Oberhauser

• With the help of a field guide to wildflowers, see if you can find milkweed growing near your school grounds. Look at the milkweed plant carefully and sketch it in your field notebook. Where are the leaves positioned on the stem? What is the texture of the leaves? The color?
• Revisit the site every few days and keep track of the milkweed's rate of growth. Measure the plant's height, and record the daily high and low temperatures. Estimate the amount of heat required for your milkweed to grow, using the equation in the "Growing Degree Day" classroom lesson. This numeric value will help you measure the pace of spring's "arrival" from year to year.
• Watch for adult monarchs regularly. Also look carefully for monarch eggs beneath the leaves. This is another way to tell if monarchs have arrived in your region! (Also, make plans to participate in Dr. Karen Oberhauser's larval monitoring study this summer.)

How to Respond to Today's Challenge Questions:

• Please do not answer both questions in one message!

How to Respond to Journey North Monarch Challenge Question # 12

1. Address an e-mail message to: jn-challenge-monarch@learner.org
2. In the Subject Line of your message write: Challenge Question # 12
3. In the body of the message, give your answer to this question:

Challenge Question # 12
"Many monarchs were sighted on April 20th. Can you name one possible reason for this which has nothing to do with monarch butterfly behavior?"

How to Respond to Journey North Monarch Challenge Question # 13

1. Address an e-mail message to: jn-challenge-monarch@learner.org
2. In the Subject Line of your message write: Challenge Question # 13
3. In the body of the message, give your answer to this question:

Challenge Question # 13

1. "When are viceroys first seen in the spring where you live?
2. At what stage of their life cycle do viceroys overwinter, as an egg, larva or adult?
3. Where do viceroy butterflies spend the winter?"

Don't Forget!
Please include the name of your school and your location so we can credit you properly for your answers.

The Next Monarch Migration Update Will be Posted on April 29, 1997