Mexican scientists have taken on an ambitious project to transplant the habitat of the monarch butterfly — which migrates south to Mexico every winter — to mitigate the effects of climate change on the butterfly’s population.
Their approach involves planting new fir forests at temperatures where the butterfly’s preferred place to hibernate can thrive.
Between late October and early November, hundreds of millions of monarch butterflies migrate 2,500 miles from the northern United States and southern Canada to hibernate in Mexico’s fir forests.
The fir tree thrives in the humid, cold climate found along the border between Michoacán and México state, home to the Monarch Butterfly Biosphere Reserve. However, climate change is gradually changing the ecosystems of Mexico’s forests, putting the monarch’s habitat under threat from increasingly severe temperature changes, droughts and pests.
“During the day, under the shade of the fir tree, the environment remains 5 degrees (Celsius) colder than outside. It is a protection against high temperatures. At night, it is the other way around, resulting in 5 degrees warmer,” Cuauhtémoc Sáenz Romero, the lead author of the study “Establishing monarch butterfly overwintering sites for future climates,” told the news site Wired.
The density of the canopy of these trees acts as protection against winter rain. “If the temperature drops below zero and the butterflies get their wings wet, they can freeze. That is why these trees represent such a particular habitat,” Sáenz added.
According to Sáenz’s study, some climate change models suggest that the climate habitat suitable for monarchs could disappear by 2090 in the existing Monarch Reserve.
“If at 3,000 meters, the fir trees had an average temperature of 10 degrees, now they will find that temperature at 3,300 meters. That is, the climate keeps moving upwards, but the trees cannot move [anywhere],” stated Sáenz Romero.
Assisted butterfly migration
Scientists and conservationists are now working together, alongside the Indigenous community of Calimaya, to move fir seedlings to higher and colder areas in the region to create new butterfly habitats.
In 2017, the team chose the Nevado de Toluca volcano in Mexico state to plant the new forests, having assessed factors such as altitude, orientation, soil type and future climatic condition forecasts.
Good news from El Rosario colony. Gradual population concentration. “They’ve kept flying all over our region since their arrival. Some are now clustering.” Remember to read our new MBF newsletter and to donate generously today – GivingTuesday: https://t.co/B1OoKqBKYt pic.twitter.com/5uw8abEBqr
— MonarchButterflyFund (@mbfmonarchs) December 3, 2024
Over the last seven years, they have transplanted seedlings from cone seeds collected from eight stands in the Monarch Butterfly Biosphere Reserve and planted almost 1,000 trees at four sites on the northeast slope of the volcano, at altitudes of 3,400, 3,600, 3,800 and 4,000 meters.
The project would not have taken off without the Indigenous community involved, Sáenz stressed. “They understand that their work implies a positive effort for their forest. In addition, they have a great sense of attachment to their territory and a lot of ecological knowledge. They know where and when to collect the seeds,” explained Sáenz.
The group must now ensure the survival of the seedlings during the first years of life, as well as consider their genetic adaptation to the new environmental conditions. The trees must be able to resist lower temperatures, stronger winds and less water availability to survive. The team aims to establish healthy trees by 2060.
During the winter of 2023-2024, the population of monarch butterflies in typical hibernation locations was down nearly 60%, according to a report from Mexico’s National Commission of Protected Natural Areas (Conanp).
While the monarchs have yet to migrate to the northwest slope of Nevado de Toluca, they were reported on the southwest side, which Sáenz said suggests they are searching for new places to spend the winter months.
The monarch visitation season
The Monarch Butterfly Biosphere Reserve in Michoacán is a popular tourist site, attracting up to 200,000 visitors every year.
The main visitor sites include Sierra Chincua, Senguio and El Rosario in Michoacán and Piedra Herrada, which is located just 18 miles from the lake town of Valle de Bravo in México state.
Conanp announced the opening of the 2024 season starting Nov. 15 and ending March 31, 2025, and emphasized the importance of ecological conservation at the reserve.
With reports from ecoPortal, Wired, CB Televisión, El Sol de Morelia and National Geographic
