By Gail Morris
February 13, 2019
February 12, 2019
Dear friends,
Welcome all to the peak of an extraordinary Monarch season at the Sanctuaries Sierra Chincua and El Rosario in Angangueo, Michoacán, Mexico.
What do the graphs reveal about the sanctuaries monarchs select from year to year? Why is it valuable to have information from more than one year? What predictions could you make about the future based on these graphs?
Every winter, scientists visit Mexico's 12 traditional sanctuaries and measure the area of forest covered by monarchs. In winter 2018/2019, the colonies covered an area of 6.05 hectares (as of December, 2018). They measure area because estimates of individual butterflies in a colony vary too widely to be reliable. Such estimates range from 10 to 50 million monarchs per hectare.
North America has two migratory populations of monarch butterflies. This collection of articles and resources focuses on the western population.