Exactly Where in Mexico Do the Monarchs Go for the Winter?
Each winter, the entire eastern population of monarch butterflies in Mexico clusters together on only 10-12 volcanic mountains, in large colonies estimated to contain millions of individuals. Significantly, an estimated 80% of the butterflies concentrate each year in only four core colonies.
All of the colonies are in Mexico's Transvolcanic Belt, and most of these colonies are spread along an arc from the western face of the volcano "Nevado de Toluca" to the northeastern extreme of the state of Michoacan. The four core sites--El Rosario, Sierra Chincua, Chivati-Huacal and Cerro Pelon--are located in the center of the arc, near Angangueo.
in Spatial Terms