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Monarch Butterfly Migration Update: November 4, 2005

Today’s Update Includes:

Latest Migration Maps
Make Your Own Map in the classroom!

Migration Sightings
Sightings of Overnight Roosts PEAK
Migration Sightings
Click for live maps and read what each observer saw! Also See
Week-by-week Migration Animation

¡Las primeras mariposas monarcas han llegado!
The official word is in! The first monarchs have arrived! On Saturday, October 29th, an estimated one thousand monarchs were seen by Germán Medina as they flew over his house in the small town of Angangueo.

Here’s his report submitted by Estela Romero:

10/29/05 Angangueo, Michoacan (19.62, -100.30)
"Early Saturday morning Germán went to "El Cerrito", thinking that some butterflies would be there, but he found no butterflies. Hours later, at noon time, when he was already at home, he says he saw some "herds" of monarch butterflies flying up towards El Rosario (sanctuary). He says there must have been around one thousand butterflies. Today, (Monday, 12:00 noon), he just came from "El Cerrito" again, and told me that there are now about 5 trees fairly covered with monarchs. So I think we can say that they have officially arrived!!!" See full report in English and Spanish:

"El Cerrito" means "the little hill." It is a high ridge northwest of town, and it takes just 10 minutes to get there by truck. German knows "El Cerrito" as the best place to watch for the monarchs' arrival. He has been visiting regularly hoping to catch sight of the first monarchs there.

Germán Medina Estela Romero Dr. Lincoln Brower
Germán Medina drives tourists to see the monarchs in this truck. He also coordinates the Symbolic Migration in Mexico. Estela Romero has graciously translated and sent news about the monarchs each week. Thank you, Estela! Dr. Lincoln Brower has been studying monarch butterflies for the past 50 years!

Germán's timing was impeccable! Dr. Lincoln Brower was in Mexico the entire week before and did not see a single monarch. He was doing research inside the actual butterfly sanctuaries, from October 23rd to 28th. He finally saw one monarch while driving back to Mexico City! Here's Dr. Brower:

10/28/05 Villa Victoria, Mexico (19.43, -99.98)
"The only monarch we saw from 23 October - 28 October was one flying over the road 13 miles north of Villa Victoria, Mexico, on our way back to Mexico City," said Dr. Brower. "We worked on our field research on Chincua on Sunday (23 October), Monday, Tuesday, Thursday and Friday, and Pelon on Wednesday. I suspect that, had the weather been better, that we would have seen more."



Finding a Finish Line About 60 Miles Wide
Stop and think for a minute. The monarchs that are now arriving at the sanctuaries in Mexico have come from points across eastern North America. This map shows the HUGE area in North America across which the monarchs are traveling. The over-wintering region is a tiny speck on the planet in comparison.

  • The monarch breeding grounds, shown in red on the map, measure over 3,000,000 square miles!
  • The monarch over-wintering grounds, shown in yellow, measure only 4,100 square miles.

After crossing half a continent, the monarchs must find a finish line about 60 miles wide!

The 12 major over-wintering sites are shown as red triangles on this map.

The monarchs fly up to 2,500 miles to spend the winter in these mountains.

Try This! Make a Local Comparison
Just how small is the over-wintering region? Pull out a map of your state or province. Compare the sanctuary area in Mexico with an area that is familiar to you:

Monarchs Sighted in the Bahamas: Where Did They Come From?
We were surprised this week when two separate monarch sightings were reported from the Bahamas! The monarchs were seen on two different islands, over 100 miles apart. Both observers said they noticed the monarchs suddenly. Each person reported the butterflies independently, too. Although not as far an over-water crossing, a tagged monarch was once recovered in Cuba.

"The Bahamas do have a population of their own, said Dr. Bill Calvert. "The yearly cycles have been studied and published."

Where do YOU think the monarchs came from?

Challenge Question #10
"Where do you think the monarchs that were sighted in the Bahamas came from? Why? Give evidence to support your interpreation."

Who Saw the Most Monarchs This Week? Migration-rate Math
Follow the link below to a few of this week's observations:

FINAL Monarch Butterfly Migration Update Coming Next Week
We will bid farewell to the fall migration season in next week's update. Watch for a summary of this fall's "migration rate math," Challenge Questions, as well as a preview of things to come when Journey North begins next February. See you next week!

The FINAL Monarch Migration Update Will Be Posted on November 11, 2005.


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