Exactly Where in Mexico Do the Monarchs Go for the Winter? Monarchs from across eastern North America funnel to Mexico's Transvolcanic Belt--and cluster on only 10-12 mountaintops on the planet. (The location of the overwintering sites are indicated by red triangles on the maps below.) 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. National Geography Standards The World in Spatial Terms How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information. Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form