The monarch butterfly (Danaus plexippus), globally recognized for its mass migrations between Canada, the United States, and Mexico, faces an uncertain future.
A study published in PLOS Climate warns that climate change could reduce its suitable habitat by 8% to 40% by 2070, shifting it towards southern Mexico and fracturing its traditional migratory routes.
Dependence on milkweed plants
Monarchs depend on milkweed (Asclepias) to reproduce and protect themselves from predators. These plants provide food and toxic compounds that defend the caterpillars and adults.
However, the increase in temperatures and alteration of environmental signals could affect their availability and modify the stimuli that trigger migration.
Prediction models
Researchers from the National Autonomous University of Mexico (UNAM), led by Francisco Botello and Carolina Ureta, used computational models to project the location of suitable habitats in Mexico for eggs, larvae, and milkweed plants in 2030, 2050, and 2070.
- The results show a progressive decrease in habitat.
- The shift southward would concentrate breeding sites in more limited areas.
- This could fragment migratory routes and alter the dynamics of millions of butterflies that travel thousands of kilometers each year.
Additional threat factors
Climate change adds to other problems already affecting the species:
- Habitat loss due to deforestation and intensive agriculture.
- Parasites and diseases that reduce survival.
- Reduced availability of food plants along their migratory routes.
Complementary study on tropical flowers
The publication coincides with another study in PLOS One conducted by the University of Colorado-Boulder, which analyzed more than 8,000 specimens of tropical flowers collected between 1794 and 2024. The results show that climate change has altered flowering times by up to two days per decade, with extreme cases such as:
- Rattle bushes in Ghana, which advanced their flowering by 17 days.
- Brazilian amaranths, which now bloom 80 days later than in the 1950s.
These changes could affect the relationships between plants, pollinators, and frugivorous animals, increasing the vulnerability of tropical ecosystems.
Ecological implications
The combination of fragmented habitats for the monarch and changes in the flowering of tropical plants poses significant risks:
- Alteration of food chains and dependency relationships.
- Increased vulnerability of pollinators and seed dispersers.
- Impact on tropical biodiversity, considered more stable against climate fluctuations, but now exposed to rapid changes.
The future of the monarch butterfly depends on the ability to mitigate the effects of climate change and conserve the ecosystems that support its migration.
Recent studies show that even iconic species and tropical flowers, previously considered less sensitive, are experiencing drastic changes. Habitat protection and emission reduction are essential to ensure that monarchs continue painting the skies of America orange and black in their millennial journeys.
