Monarch Butterflies
Migration Update: February 2, 2007
Please Report
Winter Sightings! >>

Today's Report Includes:


Today: Butterfly Trees!
Photo: Dr. Lincoln Brower
News From the Monarch's Winter Home in Mexico!

Monarchs fly to Mexico from across the continent.
They go to only twelve mountain top sites. Count them! >>

Welcome to Journey North's spring's migration season!  It's been four months since the first monarchs reached their winter home in Mexico after their long, fall migration. How many monarchs survived the trip? Today's report explores that important conservation question. Read on!
How Big is This Year's Population?

The twelve known monarch butterfly colonies in Mexico are measured every winter. These yearly measurements give scientists a chance to estimate the size of the entire overwintering population.

The Count is In! This year's butterfly trees cover
6.67 hectares*.		 That's equal to the area of
16 football fields!

*One hectare equals 2.47 acres.
How Do Scientists Know? Try Counting! >>

It is NOT EASY to know how many monarchs there actually are. In real life, the butterflies, the forest, the weather, and even the scientists are constantly moving and changing! Let's look at the scientists' methods. First, walk into a sanctuary, take a look, and try it yourself. >>

Scientists Count Butterfly Trees
Photo: Dr. Lincoln Brower, Sweet Briar College

Where Are the Butterflies? >> How Does 2007 Compare? >>

Over half of the continent's monarchs are at just two of the wintering sites! Find them on the map. >>

Compare the 2007 population to those in the past 13 years.

Journal Question: How Many Millions of Monarchs?

You learned today how scientists estimate the size of the monarch population. Because it's impossible to count monarch butterflies, they estimate how many monarch trees are in a colony. Next, they estimate the area the trees cover, in hectares. Scientists also think there are between 10 million and 50 million butterflies per hectare!

  • How many millions of monarch butterflies do you estimate there are in the population this year? Give at least two reasons you think it's hard for anyone to know how many butterflies there actually are!
Links: Monarch Butterfly Resources to Explore
  • Journal: Monarch Winter Habitat Journal >>
  • Lesson: How Many Millions of Monarchs? Why Butterflies Can't be Counted >>
  • Overview: About Journey North's Monarch Butterfly Overwintering Study >>
More Monarch Lessons and Teaching Ideas!

The Next Monarch Migration Update Will Be Posted on February 9, 2007.

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