We tell you which factors led to the repopulation of this species.

The presence of monarch butterflies hibernating in Mexican forests increased by 35% in December 2021, occupying 2.84 hectares (ha) of forest compared with 2.10 hectares reported in the same month for 2020.

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Reasons for the monarch butterfly repopulation

According to the annual report from the National Commission for Protected Natural Areas (CONANP) and the WWF-TELMEX Foundation Partnership, this is −chiefly− due to the early repopulation of butterflies in the south of the United States.

María Luisa Albores, Secretary of the Environment and Natural Resources, said that another factor was a reduction in the use of glyphosate and coordination with ejidos (communal lands) and communities, as well as the training of territorial guardians, all of which benefited these pollinizers.

For example, the federal government is carrying out productive projects with the participation of ejidos and communities from the Biosphere Reserve, which include the sale of honey products, handicrafts, and natural medicines.

Where can you find more butterflies?

This season, four sanctuaries were opened for spotting monarch butterflies: El Rosario (Ocampo Michoacán); Sierra Chincua (Angangueo, Michoacán); Senguio (Senguio, Michoacán); and Piedra Herrada (Valle de Bravo, State of Mexico), receiving around 186,000 visitors.

CONANP shared that the largest colony (1,187 ha) was recorded in the El Rosario ejido (Sierra Campanario sanctuary, Michoacán) and the smallest colony (0.003 ha) was located in the Crescencio Morales ejido (Lomas de Aparicio sanctuary, Michoacán). This colony reappeared after having been found for the last time in 2003-2004.

Butterflies were also present in the municipality of Atlautla, neighboring the lztaccíhuatl-Popocatépetl National Park, but a compact colony was not established.

Jorge Rickards, Director General of WWF Mexico, said that the increase in monarch butterflies this season is good news, as they had surpassed the 2.10 ha recorded in 2020-2021.

“In 2018-2019, the area occupied by the butterflies for hibernation was 6.05 hectares, which tells us we must continue working to maintain this trend and reinforce protection measures from Mexico, the United States, and Canada. Monarch butterflies are important pollinizers, and their migration favors the reproduction —with greater diversity— of flowering plants, which benefits other species in natural systems and contributes to the production of food for human consumption in productive systems.”