FINAL Fall Migration News: Nov. 10, 2011
Please Report
Your Sightings!

We end our fall migration season with a key question: How many monarchs made it to Mexico, and how is the population doing? Join us again on February 2, 2012 for weekly news from Mexico and preparations for spring migration. Thanks for helping track the monarch's trip!

This Week's Update Includes:

Image of the Week

How Many?

News: The Overwintering Season Begins!

It's Official
The forests are filling with butterflies! More than 250 treefuls were counted on a recent field trip reports Filipe Martinez, subdirector of the Monarch Butterfly Biosphere Reserve. See photos and read his original press release in Spanish.

The Data Everybody's Waiting For...
Every December, when fall migration is over and the monarchs are clustered tightly in their winter colonies, scientists make an important measurement. They visit the monarch's 12 traditional wintering sites and measure the surface area each butterfly colony covers. This chart shows the data scientists have collected for 17 years.

What will the scientists find this year?
That is the question on everybody's mind. Did the monarchs have a productive breeding season in the north? How many survived the long fall migration?

Scientists are waiting with interest to see what this year's results will show. The measurements made in Mexico are the most reliable estimate we have of the size of eastern North America's monarch population. Like a health check-up or a report card, the results tell us how the monarchs are doing.

Mexican biologist Eduardo Rendon of the World Wildlife Fund is the scientist who will lead the team. He will share his data with us after Journey North begins in February.

Any Predictions?
After following this fall's migration, how large do you predict this year's population will be? Do you think there will be more or fewer monarchs than in years before?

Still Seeing Monarchs? Please Let Us Know!
How long will monarchs continue to vacate the north? Tell us what you see! Late-season observations are valuable, so please help us document when and where monarchs are present.

Thank You!
Thank you for helping to track the monarch's trip! Please join us again in February, 2012. We'll begin with weekly news from Mexico, and preparations for spring migration.

Population Estimate: Monarch Butterfly Overwintering Region

The Data Everybody's Waiting For...

Did You Know?

A monarch colony contains 10-50 million butterflies in 1 hectare of forest.

You can use the chart to estimate how many millions of monarchs were in each winter's population.

Mexican monarch butterfly biologist, Eduardo Rendon
Lead Scientist
Mexican biologist Eduardo Rendon is the scientist who leads the team.

Map of monarch butterfly sanctuary region.
The Overwintering Region

Traveling With a Monarch: Tell the Story of Fall Migration

What have you learned as you traveled with monarchs on their two month, 2,000-mile journey? Tell the story of the monarchs amazing tale of survival.

Ways to tell the story:

  • Write and illustrate a book.
  • Make a "travel brochure."
  • Create a poster or display.
  • Develop a lesson to teach younger kids.

Here's a checklist for your project and a map you can draw on.

Monarch Migration Blank Map
Checklist Map
The Migration: Maps and Journal Page 
Monarch Butterfly Migration Map: All Sightings, Fall 2011 Monarch Butterfly Migration Map: Fall Roosts, Fall 2011 Journal Page

All Sightings

(map | sightings)

Fall Roosts

(map | sightings | archives)


Still Seeing Monarchs? Please let us know!

This is the final FALL Monarch Migration Update. See you in February, 2012!