Monarch Butterfly Biosphere Reserve

The Monarch Butterfly Biosphere Reserve protects high-elevation oyamel fir forests in central Mexico that serve as the overwintering grounds for the eastern North American monarch butterfly migration. Each autumn millions of monarchs arrive from breeding grounds in Canada and the United States and cluster in forested sanctuaries.

Within the reserve butterflies aggregate on tree branches in dense clusters that are visually striking and ecologically sensitive. The sites preserve critical forest habitat and microclimatic conditions required for the butterflies’ survival during the winter months.

The migratory aggregation occurs annually from late October through March, with many visitors and scientists observing colonies during the colder months when the butterflies are most concentrated. Conservation measures and regulated access are used to protect the colonies and the oyamel forest ecosystem.

The reserve occupies mountainous areas of the Trans-Mexican Volcanic Belt primarily in the state of Michoacán (and adjacent areas in the State of Mexico), within high-elevation fir forests that form the overwintering landscape.

• Seasonal timing: the butterflies overwinter in oyamel fir forests at high elevation and typically cluster from late October through March, with peak visibility in late November to February
• Visitor management: access to colonies is managed by park authorities with designated trails and viewing platforms to reduce disturbance to the butterflies and their habitat

What to See #

• El Rosario: The El Rosario sanctuary in Michoacán, a principal overwintering site where monarchs cluster in large numbers on oyamel fir branches within designated viewing areas.
• Sierra Chincua: Sierra Chincua, another core sanctuary in Michoacán, featuring steep forested slopes and established trails and platforms for regulated viewing of butterfly colonies.