The population of eastern monarch butterflies, which migrate from Canada and the US to Mexico during winter, has nearly doubled over the past year, a recent report commissioned in Mexico reveals, sparking hope among conservationists.
This modest increase in the orange-and-black butterflies follows years of continuous conservation efforts and offers a glimmer of optimism amidst otherwise disturbing long-term trends for the species.
However, a separate recent study found that the population of monarch butterflies in the US specifically declined by 22% over the past two decades. In December, the US Fish and Wildlife Service proposed protecting monarch butterflies as threatened under the Endangered Species Act in response to years of advocacy by conservation groups.
Acknowledging the need to convert short-term gains into long-term ones, Jorge Rickards, director general of Mexico’s World Wildlife Fund branch, emphasized the importance of an all-hands approach to safeguard the critical habitats along the monarchs’ North American migratory route. Rickards also recognized local communities’ vital role and the government of Mexico’s support in allowing the species to thrive.
The survey, titled “Forest Area Occupied by Monarch Butterflies Colonies in Mexico During the 2024-2025 Hibernation Season,” is a crucial indicator of the overall health of the butterfly population. It is part of a series of annual reports by WWF Mexico and Mexico’s National Commission of Protected Natural Areas, in collaboration with local communities.
Despite the growth, scientists note that the number of monarchs is still far below the long-term average. Better weather conditions in 2024, with less severe droughts compared to previous years, are likely responsible for the population increase.
At the end of summer, eastern monarchs migrate from the northern US and southern Canada to high-elevation fir forests in Mexico. The population size is determined by measuring the area of trees turned a vibrant orange by the clusters of bright butterflies.
Source: https://www.theguardian.com/environment/2025/mar/11/eastern-monarch-butterfly-population-doubles-year
