FINAL Fall Migration News: November 14, 2013
Please Report
Your Sightings!
Report Your Sightings
Monarchs are now arriving at the winter sanctuaries in Mexico. How many survived the journey? Why do they fly across the continent to reach this special place?

This Week's Update Includes:

Image of the Week
Monarch sanctuary region of Mexico
How Many?
Image: Estela Romero
News: They're Home!
"After a long delay, monarchs are now reaching their final destination at their overwintering sites in central México," says Estela. The arrival was quite sudden. People reported monarchs in the sky, flying in from the north.

Late Arrival, Low Numbers
As of November 10th, there were 10 trees filled with monarchs at El Rosario Sanctuary. This compares to 60 trees on November 1, 2011.

Population Estimates
Every December, scientists visit the 12 traditional wintering sites and measure the area of forest the monarchs occupy. This chart shows the data scientists have collected for 19 years. Results will be released in March, 2014.

Predicting This Year's Population
Can we use fall migration data to predict the size of this winter's population? Explore these graphs to make predictions.

Thank You, Citizen Scientists!
Your observations and photos told the story of this fall's migration. We are grateful and enriched by your participation. Please join us again on February 6, 2014. We'll begin with preparations for spring migration and celebrating the monarchs' return!

Monarch sanctuary region of Mexico
From the North
 

Monarch butterfly overwintering region in MexicoThey're Home

 
Population Estimate: Monarch Butterfly Overwintering Region
Population Estimates
Winter in Mexico: Month-by-month Highlights
November   December
Monarch Butterflies arriving in Mexico   Scientists visit the 12 wintering sites and measure the surface area the colonies cover.
Monarchs Arrive
Throughout the month, monarchs continue to arrive from the north and settle in at the 12 traditional wintering sites.
  Scientists Count
Scientists visit the 12 wintering sites and measure the surface area the colonies cover. Results will be released in March, 2014.
     
January   February
Monarch Butterflies wintering in Mexico   Monarch Butterflies wintering in Mexico
Surviving Cold
Watch the weather! At this coldest time of year, monarchs are at the greatest risk of mortality from deadly winter storms.
  Preparing to Migrate
Monarchs that survive four winter months will mate and begin the journey north in March. Join us for weekly updates on Feb. 6, 2014.
Slideshow: Why is this place so special for monarchs?
Millions of monarchs migrate to Mexico to spend the winter in an astonishingly small region. What conditions make the habitat in this region ideal for monarch survival? Learn about the unique microclimate of the monarch overwintering region.

Slideshow: Why is this place so special for monarch butterflies?

The Migration: Maps and Journal Page
Continue to report your sightings. Document where monarchs found this winter.
Winter Monarchs?
When you see a monarch, we want to know about it.
Monarch Butterfly Migration Map: Peak Migration, Fall 2012 Monarch Butterfly Migration Map: Peak Migration, Fall 2012 Journal
Journal

Peak Migration
(map | animation | sightings)
Winter Sanctuaries
This is the FINAL Fall Update. We're back Feb. 6, 2014