After years of decrease, the number of monarch butterflies that come to hibernate in Mexico increased by 35% in the 2021-2022 season.
The number of Monarch butterflies that arrived in 2022 to the mountains of Michoacán and the Estado de México to spend the winter increased by 35%, compared to the previous season. The data suggests that these insects have adapted to climatic changes by modifying the date of their ‘ departure’ from Mexico, according to Mexican experts cited by AP.
During the 2021-2022 hibernation season, Monarch butterflies occupied 2.84 hectares of forest , compared to the 2.10 hectares of habitat registered the previous season, says a report from the Mexican Government .
Each year, these butterflies return to the United States and Canada on an annual migration that is threatened by the loss of the milkweed they feed on and deforestation in Mexico.
However, the annual butterfly count does not calculate the total number of insects that arrive, but the number of hectares they cover when they gather on the branches of the trees.
Butterflies traditionally come to pine and spruce forests located on the mountaintops west of Mexico City in late October and early November, and fly to the United States and Canada in March.
However, last year was unusual, as monarchs began to return in February, allowing them to leave before drought and heat hit north of the border in April and May.
“They are beginning to adapt to extreme weather conditions,” says the phenomenon Gloria Tavera, regional director of the National Commission of Natural Protected Areas of Mexico (CONANP).
Interestingly, this year, the butterflies stayed in Mexico longer than usual. “They left very late. We still had butterflies in April,” says Tavera.
Although activists and students from the US and Canada have been urged to plant milkweed to compensate for the loss of the plant due to deforestation and use of herbicides, this strategy has failed in Mexico.
For his part, Tavera urged Mexicans not to plant milkweed in Mexico, since, he says, it could affect migration, encouraging monarchs to stay in that country instead of flying north.
He also called on people not to breed monarchs in captivity, as this could lead to the spread of disease among insects.