Monarch Butterfly Update: Feb. 24, 2011
Please Report
Your Sightings!

Spring migration is quickly approaching! The first U.S. sightings could appear by the end of next week. Where have millions of monarchs found the energy they needed to survive the winter? This week's focus is food. Also, Estela Romero tells what it's like to live in Angangueo's cold mountain environment the way the monarchs do. "Brrrrr!" she begins.

This Week's Update Includes:

Image of the Week

Ask the Monarch Butterfly Expert

Ask the Expert!
February 25-March 11

News: Spring is Coming, Fuel is Falling—It's Almost Time to Go!

With each passing day, spring migration is getting closer. Temperatures are rising and the risk of freezing is falling. Monarch activity is a frenzy on warm sunny days. Mating increases dramatically now, and the butterflies leave their clusters continually to head out in search of water.

This is the time "colony break-up" occurs. Butterflies leave their tightly-clustered colonies and they no longer return at night. The presence of loose clusters is a sign that the colonies have begun their spring expansion.

People love to visit the monarchs at this time of year because the butterflies are so active. During a trip last week, the Hind family encountered thousands upon thousands of thirsty monarchs. The butterflies are pictured here, drinking from seeps and streams. Look closely and notice the wear and tear of some butterflies' wings. It has been a long winter!

The monarchs must still survive another challenge. They're running low on fuel. Look at the falling lipids on the line graph that's based on Dr. Lincoln Brower's research. How much longer could the monarchs stay in Mexico before they'd run out of fuel?

"Running out of fat is a common cause of mortality," says Dr. Bill Calvert. Many monarchs simply starve. They don't have enough lipids in reserve to last the winter.

Attention All Butterfly Gardeners: Get ready, because very hungry monarch butterflies will soon be heading north!




Thousands of butterflies cover the ground.


Thousands of butterflies cover the ground.

Tattered and Torn

Graph: Lipids
Falling Lipids

Slideshow: No Food for Five Months?

People eat three meals a day, 365 days a year. How can monarch butterflies survive without food for so long? This slideshow shares their secret.

Journal page

Life in the Monarch Butterfly Sanctuary Region

It's cold in Angangueo!
The cold mountain temperatures of central Mexico make survival possible for monarch butterflies. For people, on the other hand, it's challenging to endure the cold, especially at night. Temperatures often drop to freezing, and there is no indoor heat.

"When going to bed at night, Laura Emilia has to put on very warm pajamas and socks. If necessary, she wraps up her feet. Laura Emilia's bed has 7 blankets!" says Estela.

Warm pajamas at night in Angangueo

Laura Emilia has 7 blankets!

Journal: My Day as an Ectotherm

Imagine how your day would change if you woke up as an ectotherm one morning! A monarch butterfly is an ectotherm—a cold-blooded organism whose body temperature depends on its environment rather than internal sources of heat. Write about the changes you would have to make to live your day as a cold-blooded organism, no longer warmed from the internal processes of metabolism.


My Day as an Ectotherm: Journal Page

Seeing Monarchs or Milkweed? Please Report Now!

All monarchs do not go to Mexico! Before spring migration begins, please help us document where monarchs are located this winter and where milkweed is available.

Map of monarch wintering sites in Mexico Pre-migration map: Winter monarch butterfly sightings (January or February) Map of milkweed emergence: Spring 2011

Mexico's Monarch Butterfly Wintering Region

Monarch Butterfly
Winter Sightings

First Milkweed
The next Monarch Migration Update will be posted on March 3, 2011.