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Monarch Migration Update: October 25, 2002

Today's Report Includes:

Field Notes from the Monarch Sanctuary Region in Mexico
Only two more butterflies to report this week from Angangueo...Last year, the first monarchs were reported all at once, from multiple places, beginning October 12. (Including this favorite: "At the moment the children at Escuela Secondaria Rancho Escondida were honoring the Mexican flag they saw 6 butterflies fly by. They all screamed with surprise!")

Predictions please! When do you think the first big wave of butterflies will reach the sanctuary region? By next week’s update? Here are this week’s observations, in both Spanish and English:

Highlights Along the Migration Trail

(Almost) All Quiet on the Texas Front
We continued to hear migration news from Texas during the past week, but most everyone was still talking about the amazing migration of the week before! Clearly the season’s first big push occurred early last week. So few have been seen since, people in Texas wonder whether they’ve had their only big show for the year.

And what a clear wave it was! Mr. Tony Gallucci has been monitoring the migration every day since September 15 in Hunt, Texas. Graph his daily counts and you’ll see how dramatically numbers spiked over a two day period!

Monarchs Resting on Mesquite in Texas
October, 2002

Photos courtesy of Carol Cullar

Plane Changes Course to Avoid Monarchs in Texas
While leading a field trip, Charlie Parides witnessed an amazing spectacle last Sunday in Starr County, Texas. From the ground, ten to twenty thousand monarchs were seen soaring in a huge "kettle configuration," similar to the flight of hawks in a thermal. He described it as a "southwardly migrating body of Monarchs."

"It was monarchs as far as you could see," said Parides. "The lowest flying Monarchs observed were at around 500 feet high and the kettle, or group, consisted of monarchs dispersed vertically up to 2,000 feet. I am a private pilot and judged the altitude from a small aircraft flying nearby at an altitude of about 2,000 feet. The pilot maneuvered his aircraft in order to avoid the mass of butterflies. Most of the folks on the field trip I was leading had also never seen anything like this before. It was a unique treat. I was at the same exact location the next day and there wasn’t a single monarch in the sky."

How High Do Monarchs Fly?
How high do monarch butterflies fly during fall migration? Do they go as high as the clouds? Higher than the naked eye can see? And why do they fly at such high altitudes? We posed these questions to monarch biologist Dr. Bill Calvert:

Read Dr. Calvert's comments, then answer these questions:

Challenge Question #12:
"If a glider pilot has seen monarchs flying 11,000 feet in the air, how high is that in miles? In kilometers?"

Challenge Question #13:
“Why do you think Dr. Calvert says that on the BEST migration days people sometimes see the FEWEST monarchs?”

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

Up, Up and Away: From Skyscrapers to Outer Space

Try This!
How High Can YOU See a Monarch?

At what height do monarchs disappear from view? Try the experiment Dr. Calvert suggests and send us your results.

How high do jets, hot air balloons, migrating birds and butterflies fly? How high are satellites, clouds, and the world's tallest trees and buildings? Make a model of the earth's atmosphere on the highest wall you can find. Using the altitudes provided in this lesson, start on the ground and go to the edge of outer space.
Monarchs in Pecan Trees?!
Discussion of Challenge Question #10

Can You Find the Honeydew?
(Click to view.)

Last week we asked, "Why are so many monarchs found in pecan trees in Texas?" Our tip: Learn about insects called "aphids" to answer this question.

And learn about aphids Ms. McCabe's students in Midland, Texas, did! Here is their answer:

"My class thinks monarchs are found in pecan trees because they feed off of the honeydew that is produced by the aphids. We found an aphid website that stated that aphid always feed in clusters. We concluded that aphids feed in clusters of large numbers in the pecan trees, and produce a sugary-like substance called 'honeydew.' This 'honeydew' would attract the monarch since they feed on sugary substances."

Did you think monarchs ate only nectar? "Monarchs are interested in drinking fluids containing sugar during their migration," says Dr. Bill Calvert. There are lots of aphids and lots of pecans in this part of the world (Texas). Monarchs have been known to 'feed' ('take-in sugar' would be a better way to describe it), on honey dew deposited by aphids on pecan leaves. Honey dew coated pecan leaves, yum!" (Honeydew is a waste product, reminding us that EVERYTHING is recycled in nature.)

Washed Ashore in Florida
Monarch With Tag
Photo: Gayle Kloewer
Discussion of Challenge Question #11
Last week Mr. RuBi no told us that only 3 of his 12,500 tagged monarchs had been recovered in Mexico. He said this recovery rate is very, very low. Overall, an average of one in 100 tagged monarchs (1%) is recovered in Mexico. We asked, how many recoveries you would expect if one in 100 of Mr. Mr. RuBino’s monarchs had been recovered. Are you ready?

Mr. RuBino would expect 125 recoveries in Mexico! So why has he only had three?

Where Do Monarchs Tagged on the Florida Coast Go?

What happens to monarchs once they reach the Florida coast? We plotted his tag recoveries on this map. Mr. RuBino describes what he’s learned:

"I know for certain that, in the fall, monarchs passing through this area spread fairly equally to the west and southeast. We've had a few recoveries along the Gulf coast to the west of us, and some recoveries southeast of us, down the peninsula. Since only 3 of the almost 12,500 monarchs tagged at St. Marks since 1988 made it to Mexico, I fear that most of them end up in the middle of the Gulf of Mexico."

The Importance of Negative Data
Lessons Learned from Mr. RuBino

By the way, this research shows how important it is to collect negative data. Mr. RuBino kept tagging monarchs even though his results were negative (no tag recoveries). Look how many years it took to tag 12,500 butterflies! Surely he must have been discouraged at times, but he didn’t give up. As you look at the map showing his tag recoveries, think about what his perseverance has shown us about monarch migration! What did you learn? What new questions do his data raise?
How to Respond to Today's Challenge Question

1. Address an e-mail message to:
2. In the Subject Line write: Challenge Question #8 (or #9).
3. In the body of the message, answer the question above.

The Next Monarch Migration Update Will Be Posted on October 25, 2002.


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