Area occupied by overwintering monarch butterflies in Mexico has shrunk drastically in the past 30 years

Eastern monarch butterfly populations in Mexico’s oyamel fir forests, measured by hectares of land occupied, have declined sharply in recent decades, raising concerns about the butterflies' survival. Scientists estimate that a minimum of 6 hectares of overwintering monarchs is needed to sustain the species.

Bar chart showing decreasing trend in landmoccupied by overwintering eastern monarch populations, from a recent high of 18.2 hectares in 1996-1997 to less than one hectare in 2023-2024