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Monarch Butterfly Update: April 7, 1998

Today's Report Includes:

Latest Migration News and Data
The migration has been passing through Texarkana, Arkansas over the past week, where Anita Brisco of Kilpatrick Elementary was watching: "On April 4 we were driving near Ashdown, AR and found a flower meadow by the lake where we counted about 40 Monarchs feeding - mostly on dandelions. We have seen several monarchs in the past several days - several were feeding. The ones on the wing seemed to be traveling East to North east. We have native milkweed that is beginning to come up in some containers in our backyard so we hope to have some butterflies visit very soon." (abrisco@darkstar.swsc.k12.ar.us)

Analyzing Migration Patterns, Year to Year
How does this spring's monarch migration compare to last year's? These maps include all monarch sightings reported through March of each year.

Monarch Migration Through the Month of March

Spring, 1998 Spring, 1997

Try This

  • List all the factors you think might cause the migrations to be different in 1996 & 1997.
  • List all the factors that might cause the data to be different from year to year.
  • Review the lesson, You're the Scientist: Verifying Data Collected by Peers"
  • Teachers: Guide a classroom discussion using the list of questions below. If you'd like to share the ideas this discussion generated in your class, please send a message to: jnorth@learner.org

Field Notes From Texas

April 7
"Monarchs are everywhere in small numbers in all parts of central, east central, north, and northeast Texas. A few have been spotted in the Panhandle. There's been much activity in the Longview area of east Texas. Monarchs have been reported laying eggs in virtually all parts of central and east-central Texas. Still no reports from west Texas or from the Piney Woods area of east Texas. Look for them around milkweed fields, around flowers, especially flowering trees."
Bill Calvert
Texas Monarch Watch

Mark Your Calendar
The next generation of monarchs is now developing. If you live in the north, YOUR first monarch of the season may be the offspring of these Mexican migrants.

Depending on temperature, the time for development varies. But the average number of days the monarch spends at each stage of development is:

Stage

# Days

Egg

3-5

Larvae

9-14

Chrysalis

8-13

Challenge Question #9

"If we consider the peak of egg laying is now occurring in areas where monarchs have been spotted, what date would we expect to be the peak date for adults to emerge--and continue the journey northward?"


For simplicity, consider April 7th as the peak date of egg laying. But remember: In reality, monarchs are now at various stages of development all across their range. This question is only intended to help build an understanding of the timing of monarch generations.

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

Adios Angangueo: Last Monarchs Now Leaving
Lincoln Brower and I just came back from Michoacan Thursday, April 2nd. There were still some butterflies flying around Angangueo on the way out, but they were gone from Rosario and Chincua. Though they are practically gone, we were able to sample a few as they were leaving. The butterflies' crops were full, and now we're wondering if it's nectar or water.

We walked through Chincua and saw 35 piles of logs, arranged in perfect rows, waiting for the truck to come pick them up. Apparently it's what the logging permits allow them to cut but it was terribly sad to see them.
Monica Misserie
Mexico City

Discussion of Challenge Question #8
In our last report, the question of monarchs crossing the Gulf of Mexico was raised. Because the 500-mile trip would take much longer than 12 hours, travel in the dark would be necessary. We asked:

Challenge Question #8
"Why do you think it's unlikely that monarch butterflies migrate at night? List as many reasons as you can."

We compiled all the ideas below which were contributed by the following students:

  • 7th Grade at Richard Butler School (cyberkids@nac.net)
  • 5th Grade at Annunciation School (leslie.smith@annunciationmsp.org)
  • Astoria Elementary 4th Grade (mclark0@roe22.k12.il.us)
  • Mr. Schmidt's Class at Bath Middle School (ba_schmidt@limaO.noacsc.ohio.gov)
  • Miss Greenstone's class at Katonah Elementary (GREENSTONE@kes.lhric.org)
  • 7th Grade Students at Laytonville Middle School (bpayne@mcn.org)

Here are the reasons they gave:

  • Monarchs need to be warm when migrating, and it is likely to be colder at night--too cold for the butterflies to fly.
  • The wind dies down too much at night. If it is calm, there wouldn't be enough breeze or thermals to help them glide along.
  • The butterflies don't have the ability to use the stars to navigate. The monarchs can't see well at night so they would get lost. They can see better in the daytime.
  • In the dark the monarchs won't be able to find flowers to get nourishment if they get tired during the long flight. Even if they the butterflies did find flowers in the dark, many flowers close up at night so the monarchs couldn't get to the nectar.
  • They couldn't see their predators (songbirds, bats, a spider web, etc.) coming at them in the dark, so they wouldn't know to changedirection or hide.
  • It's too dark at night for the monarchs to find a resting place safely.
  • The monarchs aren't nocturnal animals. Instinct tells them to fly during the day.

Paul Cherubini, of California's Monarch Program shared these observations:

"My experience has been that approximately 20-30 minutes after sunset, monarch butterflies will not fly no matter how warm and calm field conditions may be.

"If, on a warm, calm, full moonlit night, the butterflies are shaken from a roost or tossed into the air the butterflies soon crash into nearby objects or the ground - they do not seem to be physically capable of "seeing" and maintaining oriented flight back to nearby trees.

"Therefore, I am highly skeptical of the concept that monarch butterflies might be capable of remaining air borne at night and in this way, possibly cross the Atlantic ocean or Gulf of Mexico. I believe trans-oceanic journeys are possible only if the butterflies are lucky enough to find and stay with a ship, or hopscotch from one oil drilling platform (or land island) to another. Keeping up with a ship is actually more difficult for the butterflies than it might sound because modern ships move at roughly 20-30 mph and this creates gusty, turbulent winds on the deck.

Paul Cherubini
paulcher@concentric.net

Prepare to Make Good Field Observations
Please print the Journey North Monarch Migration Checklist and take it with you in the field. Take notes on all of the following topics. When you report your monarch sightings to Journey North, please include as much of this information as possible in the "Comments" section of your report:

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 your message write: Challenge Question # 8
3. In the body of the message, answer the question above.

The Next Monarch Butterfly Migration Update Will be Posted on April 14, 1998.

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