Monarch butterflies have started to arrive in Mexico as part of their annual migration from Canada and the U.S., reported the organization Protection of Mexican Fauna (Profauna), based on observations made in the northern states of Mexico.
Each year, the monarchs embark on a 4,000 km journey to migrate from their breeding grounds in the U.S. and Canada, to overwinter in the warmer forests of the Monarch Butterfly Biosphere Reserve in central Mexico.
These sanctuaries are critical for monarch butterfly hibernation since 87% of the total population of butterflies converge here each season. There are four reserves open to tourism in the states of México and Michoacán.
Profauna encouraged the population living in the northern states of Coahuila, Nuevo León and Tamaulipas, to report their sightings, and citizens began reporting times, weather conditions and GPS locations of observed butterflies.
The monarch butterfly is a species with “special protection” under Mexican law. Due to the destruction of its habitat and to climate change, the migratory species was also added to the endangered species list of the International Union Conservation of Nature (IUCN) this year owing to a decrease in its population over the last decade.
However, in the 2020-2021 hibernation season, the WWF Mexico reported that the butterflies’ presence in and around the biosphere,grew from 2.10 hectares to 7.02 hectares – a “fragile” but positive improvement that represents an increase of 35% compared to the previous season.
“The growth in the monarch population is good news and indicates that we must continue working to maintain and strengthen conservation measures in Mexico, the United States, and Canada,” said Jorge Rickards, Director General of WWF Mexico, in a statement.
The butterflies are estimated to begin arriving at the biosphere no later than Nov. 1, coinciding with Day of the Dead celebrations. However, Rocío Treviño, the program’s coordinator, anticipated that the highest migration peak will not be recorded until the third seasonal cold front.