Monarch Butterflies 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! How Are the Colonies Measured? Why Not Estimate Numbers of Butterflies? A Story and a Lesson About Science Suggestions for Analyzing Population Data Butterfly Trees From above, a monarch colony looks like a golden carpet. How many football fields would last year's population cover? >> Education Standards >> Facebook Pinterest Twitter © 1997 – 2019 Journey North. All rights reserved.