Monarch Update: February 18, 2010
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Your Sightings!

This week's word is survival. The strong spirit of the people of Angangueo survives as they pick up the pieces of their lives, literally and figuratively. Monarch butterflies migrate to Mexico to survive. So what happens to the butterflies when a strong storm and below-freezing temperatures strike their winter refuge?

This Week's Update Includes:


Image of the Week

President of Mexico Visits Angangueo

News: Butterflies After the Storm

Signs of Survival!
How did the rainstorm that hit Mexico two weeks ago affect the monarch butterflies overwintering there? Early reports from tourists visiting the colonies are promising. Clearly, thousands upon thousands of beautiful butterflies survived the storm as you can read in Kim Baily's observations in the Chincua and Pelon monarch sanctuaries:

The Worry: Wet Butterflies and Cold Temperatures
Although these signs are promising, a scientific assessment of the complete region has not yet been done. Scientists are watching with concern because the weather conditions were a recipe for disaster: wet butterflies and below-freezing temperatures.

“The worst possible scenario for the monarchs is for them to get wet, and then for the temperature to drop when the sky clears,” says Dr. Lincoln Brower. "The key will be to see how cold it got after the rain. We will know soon when we examine our Weatherhawk data from the Chincua sanctuary."

Exactly How Cold Can a Butterfly Be?
From studies after a previous winter storm, Dr. Brower learned how critical each degree below freezing can be for wet butterflies. Here are the temperatures:

Wet Butterflies
How Cold?
How Bad?
5% killed
40% killed
80% killed

Dead or Alive?
Dr. Brower says visual observations in a colony can be deceiving. Monarchs that appear to be clustering might not actually be alive. He shared this gruesome observation: it's actually possible for dead butterflies to remain in their clusters. Here's why: monarchs hang in their clusters effortlessly because of special claws on their feet. (The cold temperatures the butterflies regularly experience during the winter paralyze them.) After a previous storm, Dr. Brower witnessed clusters of dead butterflies falling to the ground many days after they had been killed by the cold. To learn more about how monarchs hang on when they're cold see:

An Important Year to Survive
This winter's population was at a 16-year low based on measurments made in December. How many monarchs will survive the winter and migrate north in the spring? That is the important question on everybody's mind. Let's hope mortality from the February storm was minimal!

How many monarchs now?
The monarch population was at an all-time low before the February storm.


Rain in the dry season?
It's unusual to have a substantial rainstorm in Mexico during the dry season. Look at Mexico's normal precipitation patterns in this animation.


Slideshow & Teacher Guide: Temperature and Survival

Why do monarchs migrate long distances to spend the winter in a place that is so cold? What are the risks and benefits of Mexico's cold climate? This booklet and slideshow explore the relationships between temperature and monarch survival. The accompanying Teacher Guide includes activities, handouts, and a template for students to write their own fact book.

Temperature and Survival:

Teacher Guide

Journal: Think by Analogy

How Does the Forest Protect the Monarchs?
Dr. Lincoln Brower says the monarch's forest is like an umbrella and a blanket. Analogies help us understand new things because they draw upon our past experiences. This journal page has students use analogies to describe how the forest protects monarch butterflies.

Journal Page
Think by Analogy

Seeing Monarchs or Milkweed? Report Now

All monarchs do not go to Mexico! Please help us document where monarchs are located this winter, and whether milkweed is available.



Research Question and Links: Explore!

This Week's Research Question:
What adaptations do monarchs have to survive in cold temperatures in Mexico?

Explore these links to do your research:

Additional links to explore:

More Monarch Lessons and Teaching Ideas!

The Next Monarch Migration Update Will Be Posted on February 25, 2010.