Cold-Blooded Creatures Save Energy in the Cold
Last week, Challenge Question #2 asked you to explain why monarchs burn less energy in cold temperatures. After all, we're just the opposite. People burn more energy in cold temperatures, trying to keep warm.

"Because their bodies slow down," answered Gaby, a second grade student in Massachusetts, just like an expert.

“Since monarchs (and other insects) are cold-blooded, they do not use much energy when they are in a cool environment,” says monarch expert Dr. Karen Oberhauser.

As warm-blooded beings, this may be hard for us to grasp. Learn what it means to be cold- or warm-blooded. Then try some activities so you can see, feel, and think about the differences.

• Fact Sheet and Classroom Activities

No Food for Five Months! How Do Scientists Know?
Scientists say that the monarchs can survive all winter eating little or no food at all. Yet no scientist has ever watched a butterfly for the full overwintering season.

• Ask yourself as you read this update today, "How do scientists know?" Look for the evidence that supports this amazing theory.

How Much Fat Left in February?
Look carefully at this graph:

• What has happened to the monarchs since they arrived in November?
• How much fat (lipids) does the typical monarch have left now?
• What can you infer from this graph about the monarch's winter habitat?

Write down your thoughts!

So Many Monarchs...
Just look at all of those butterflies. It's impossible to count them! Scientists estimate that anywhere from 10 to 50 million monarchs share a single hectare. (What is a hectare?)

...and So Few Flowers
When he talks about the monarch's winter habitat, Dr. Lincoln Brower says:

“These high altitude sites have few flowers on which butterflies can feed."

If the monarchs were all hungry and looking for food, imagine the millions of flowers they would need!

Try This! Putting Large Numbers into Perspective
It's hard to picture such large numbers. Let's assume a single sanctuary contains 50 million monarchs. Now find 50 million people who live near you:

• Find the population of your state or province.
• Then start adding!
• Add the population of as many neighboring states or provinces you need until you reach 50 million.

Print a copy of the map to the right. Shade each state or province as you add its population.

• Where are your 50 million nearest neighbors?

A Cool Habitat Feature: No Need for Food
The monarch’s winter habitat is unique: rather than provide food for millions upon millions of butterflies for five long months, its cool temperatures let the monarchs SAVE energy.

Challenge Question #3
"If it’s true that monarchs do not eat while they are in Mexico, then when and where DID they get the food energy that they are burning now?"

• To respond to this Challenge Question, please follow these instructions.