The 2025-2026 winter season recorded a 64 per cent increase in the presence of Monarch butterflies in Mexico’s overwintering forests. The colonies occupied 2.93 hectares, up from 1.79 hectares in the previous season. The rise reflects improved breeding conditions in North America and better migration conditions to Mexico, supported by greater nectar availability from flowering plants.
Seasonal Population Recovery
The increase was linked to more eggs and larvae being recorded during reproduction in the United States. Spring and summer were less dry than in 2024, which improved breeding success. Reduced drought during migration also helped Monarchs reach Mexico in stronger numbers.
Colony Distribution in Mexico
Nine Monarch butterfly colonies were recorded this season.
- Three colonies were found in Michoacán.
- Six colonies were found in the State of Mexico.
- Five colonies covering 2.27 hectares were inside the Monarch Butterfly Biosphere Reserve.
- Four colonies covering 0.66 hectares were outside the reserve.
Long-Term Trend and Forest Protection
The occupied area is the second consecutive annual increase, indicating a short-term recovery trend. The lowest recorded occupancy in recent decades was 0.67 hectares in 2013-2014, while the highest was 18.19 hectares in 1996-1997. Forest loss in the core area of the Monarch Butterfly Biosphere Reserve also declined sharply, with 2.55 hectares affected between February 2024 and February 2025, compared with 3,728 hectares in the previous year.
Conservation Significance
Illegal logging in the core zone of the reserve has been practically eradicated since 2008. Conservation efforts have helped protect the hibernation habitat of the Monarch butterfly, which remains a symbol of ecological cooperation between Mexico, the United States and Canada.
Last Modified: April 29, 2026