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Monarch Migration Update: November 1, 2002

Today's Report Includes:

Field Notes from the Monarch Sanctuary Region in Mexico
Maybe the monarchs won’t find the sanctuaries this year! Just think: They’re traveling to a place they’ve never been. They’re flying across the continent toward a tiny spot on the planet. Or so we believe... Do you think the monarchs will make it? By next week's update? We’ll see! Being there, watching the sky, is like waiting at the airport for someone special to arrive on an expected flight. Other than a few single sightings, the sky remains empty and silent.
German Medina writes from Angangueo

Here are this week's observations from Angangueo, in both Spanish and English:

Highlights Along the Migration Trail
Exciting sightings occurred this week in Texas, Coahuila and Nuevo Leon:

On the Texas Coast, the Aschens heard monarchs were abundant 130 miles up the coast on Tuesday. So Mr. Aschen went out on Wednesday and saw something spectacular: Thousands of monarchs per hour crossing Lavaca Bay.

“Several times I held my arms out in front of me, with thumb tips touching and between my upward pointing index fingers (framed!), and I could see twenty-five monarchs.”

At sunset, the butterflies stopped crossing and turned back, and Mr. Aschen made a discovery:

“We've tried for years to figure out where the monarchs that were trying to cross the bay in October and November might cluster for the night. This was the first time to be in the right place and I was standing in the middle of hundreds that were milling around between 5:30 and sunset about 5:45. I saw more monarchs during those two hours yesterday than I have seen in the past seven years combined ... it was fantastic!”

Clustering at sundown for night-time roost. Lavaca Bay, Texas
Photos by Harlen Aschen

The Second Wave: Migration Along the Texas Coast
In Texas, the migration typically moves through on two different flyways, at two different times, or pulses. The first pulse travels down what's known as the central flyway and the second pulse moves along the coastal flyway. Do the monarchs on the central flyway arrive earlier, because they come from the Mid-western prairie states? Similarly, do the coastal Monarchs come later, from east of the Mississippi River, because they have to travel further? Do you think the Fall 2002 migration map reflects such a pattern?
Peak Migration in Coahuila and Nuevo Leon
A flurry of monarch reports also arrived from the northern Mexican states of Coahuila and Nuevo Leon:

10/28/02 Monterrey, Nuevo Leon
On October 28, Nydia de la Cruz took this picture of the sky overhead filled with monarchs in Monterrey, Nuevo Leon. “It is not very clear, but the monarchs are really high up in the sky,” writes Señora de la Cruz. How many monarchs can you count?

10/28/02 La Madrid, Coahuila
“Llegan las mariposas!” wrote Imelda Puente from La Madrid, Coahuila. “Las fotos tomadas en La Madrid en los canales en donde duerme la mariposa.”

Resting & Refueling in La Madrid, Coahuila
October, 2002

Photos courtesy of Imelda Puente

10/25/02 Saltillo, Coahuila
“La migración fue espectacular el viernes, sábado y domingo (25, 26 y 27). El viernes llovió casi todo el día, a medio día paró unas horas la lluvia y aparecieron mariposas por miles en el cielo, dando vueltas, no en su camino al sur, esa noche llovió mucho y amaneció muy nublado, a las nueve de la mañana las nubes empezaron a levantarse y aparecieron las mariposas, en remolinos, tomando las termales y elevándose alto en el cielo. Mi nieto y Yo contamos las que pasaron por la casa y contamos ¡10,014 mariposas! en 35 minutos.”

Challenge Question #14: ¿Cuántos por minuto?
“How many monarchs per minute did Señora Treviño and her grandson see?”

(To respond to this question, please follow the instructions below.)

The Migration Pathway Through Mexico by Dr. Bill Calvert
Millions upon millions of butterflies are now traveling across Mexico toward the sanctuary region. Dr. Bill Calvert describes the migration pathway:

“At the latitude of the southern tip of Texas, the monarchs' flight path is only about 8% as wide as it was when they started from their breeding grounds in the north. Enormous numbers of monarchs travel through the mountainous areas in the Mexican states of Coahuila and Nuevo Leon, and further south, because geographic features compress the monarchs' flight-path. This funneling is due to the Gulf of Mexico and Mexico's Sierra Madre Oriental (the Rocky Mountain's extension into Mexico).”

Mexico's Mountain Ranges
The Sierra Madres are shown in green, the Transvolcanic Belt in blue.

Location of Mexican Sanctuaries
Within the Transvolcanic Belt, monarchs overwinter on the mountaintops shown in red.

Try This!
Print a copy of Dr. Calvert’s description of the migration pathway. On a map of Mexico, find and highlight each town he mentions. Make a list of all the towns and states.
  • Which Mexican states does the migration typically pass through?
  • When you look at the towns you highlighted, can you see the angle of the pathway? Describe what you see.
  • What does Dr. Calvert find “delightfully confusing”?
  • When they travel through which area does Dr. Calvert say “we just don’t know where the monarchs are”?

Challenge Question #15:
“How far do the monarchs travel across Mexico to reach the sanctuaries? Measure the distance from Del Rio, Texas (30 N, -101 W) to Angangueo, Michoacan (19N, -100 W). Give your answer in both miles and kilometers. Also, for perspective, name a place that is equally distant from your own home.”

(To respond to this question, please follow the instructions below.)

How High? Discussion of Challenge Question #12
Last week Challenge Question #12 asked, "If a glider pilot has seen monarchs flying 11,000 feet in the air, how high is that in miles? In kilometers?"
  • The answer: About two miles!
    (11,000 feet divided by 5,280 feet/miles is 2.08 miles (or 3.3 km).

Migration Paradox: Discussion of Challenge Question #13
Challenge Question #13 asked you to explain this paradox: Why might people sometimes see the FEWEST monarchs on the BEST migration days?"
Mrs. Nunnally's second grade class in Bedford, NH and Nick V. from Mrs. Lodge'sclass in Hebron, CT knew:

“The reason we don't see many monarchs during the best migration days is because they're so high up, “ says Nick. The New Hampshire students added, “They will be flying high to get the fastest winds to help them go south.”

Great thinking! This is an important reminder: The information we have about migration is based ONLY on our observations. Before drawing conclusions, we have to consider what might be taking place that we cannot see!

Días de Los Muertos, Monarchs and Mexican Legend
Tonight when you are sleeping, many people in Mexico will be wide awake commemorating the “Días de los Muertos” (Days of the Dead). Rooted in the ancient Aztec tradition, and blended with Christianity, the holiday is a mix of customs and beliefs. The Mexican people honor and remember their ancestors, whose souls are believed to return to earth each year at this time. Some people spend the night at the cemetery, beside the graves of their loved ones. Rather than a time to mourn, this holiday is viewed as a time to remember. Only when we forget them, does a person really die, it’s said. Gifts and favorite foods are left for the returning souls on special alters called “ofrendas.”

In the mountains in Michoacan, some say the monarchs represent the returning souls of the dead. Every year, they see the butterflies arrive at the same time as the Días de los Muertos.


An even older tradition connects monarchs to the corn harvest. In Purepecha, an indigenous language of the region, the word for the "monarch" is the "harvester." For hundreds of years, the monarchs' arrival has told the native people that it's time to harvest the corn.

Haciendo pan de los muertos con la familia Moreño

The Moreño family shares their mountain home with the monarchs. You can see the El Rosario sanctuary on the mountain beyond their house. One November, Dr. Bill Calvert and I visited as the family was preparing for the Días de Los Muertos. Señora Moreño was baking special loaves of bread called “pan de los muertos” (bread of the dead) in her wood oven. We hope you’ll enjoy your visit!

How to Respond to Today's Challenge Question

1. Address an e-mail message to:
2. In the Subject Line write: Challenge Question #14 (or #15).
3. In the body of the message, answer the question above.

The Next Monarch Migration Update Will Be Posted on November 8, 2002.


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