Dynamics and trends of overwintering colonies of the monarch butterfly in Mexico

Monarch butterfly overwintering colonies in Mexico have experienced a significant decline, with the surface area occupied by butterflies dropping 44% between the 2012–2013 and 2013–2014 seasons—reaching the smallest recorded level in two decades. Only three of the 19 monitored colonies showed consistent presence throughout all seasons, while the total cumulative forest area used by monarchs was 106.53 hectares, with 83.68% within the Monarch Butterfly Biosphere Reserve. This decline is attributed to habitat loss due to herbicide use and land-use changes in the U.S., extreme climate conditions across North America, deforestation in Mexico, and unregulated tourism. The study underscores the urgent need for protection and restoration of overwintering sites and migratory habitats to conserve this iconic species.

Vidal, O., & Rendón-Salinas, E. (2014). Dynamics and trends of overwintering colonies of the monarch butterfly in Mexico. Biological Conservation, 180, 165–175. https://doi.org/10.1016/j.biocon.2014.09.041