Every year monarchs migrate to Mexico from across eastern North America. They cluster by the millions in 12 mountain sanctuaries. Because the butterflies are gathered in one small region of Mexico, scientists have a chance to estimate the size of the entire migratory population once each year.
Explore authentic data through graphs and maps.
1. Explore how scientists estimate the size of the monarch population in Mexico's overwintering region each year.
Scientists cheered today at a press conference in Mexico City when this year’s official monarch population estimate was announced.
The clustering butterflies cover 14.9 acres (6.05 hectares) of forest, the highest recorded since 2006 and an increase of 144% from last winter.
Before spring migration begins, let's document where milkweed and monarchs are present. Please report your sightings!
For its first 25 years, Journey North was fully supported through the generosity of Annenberg Learner. With the goal of securing a sustainable future, we have found a trusted citizen science partner to take over the initiative and continue its legacy. In February 2019, Journey North joined the UW–Madison Arboretum as a significant addition to the Citizen Science program. Your support is essential to sustaining Journey North’s future.
