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How Many Monarchs in Mexico?
Winter Population Estimates

All of the known butterfly colonies in Mexico are measured once each winter. Like a snapshot in time, these annual winter measurements give scientists a chance to estimate the size of the entire overwintering population.

Winter 2006/2007: The butterflies covered 6.67 hectares. (One hectare equals 2.47 acres.)

How will the winter of 2007/2008 compare?

The graph above shows each winter's population estimate since the winter of 1994/1995. Since that time, when was the population the highest? The lowest? How do this year's numbers compare?

What is a monarch colony? Look at the photo to the right. The orange you see in certain trees are monarch butterflies! This is a monarch colony. Find out how scientists measure and estimate monarch numbers.

Learn More!

Butterfly Trees
From above, a monarch colony looks like a golden carpet.

How many football fields would last year's population cover? >>

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