The count of the western population of monarch butterflies in California, conducted in November and December 2025, recorded 12,260 individuals at 249 observation points. Although the figure is higher than in 2024 (9,119), it remains the third lowest record since 1997, according to the Xerces Society.
The National Wildlife Federation (NWF) urged the U.S. Fish and Wildlife Service to list the species as threatened, to coordinate resources and conservation measures.
A species in decline
The monarch butterfly is divided into two populations:
- Eastern: winters in the mountains of central Mexico.
- Western: concentrates on the coast of California.
The lowest record occurred in 2020, with just 1,901 butterflies. For experts, the current figures reflect a trend of continuous decline.
Main causes
Scientists point to three critical factors:
- Climate change: disrupts migratory cycles and food availability.
- Habitat loss and fragmentation: reduces breeding and resting areas.
- Excessive use of pesticides: directly affects the plants they depend on, such as milkweed.
Voices of alarm
- Rebeca Quiñonez-Piñón (NWF): “It is necessary for the Fish and Wildlife Service to no longer delay the protection of the monarch butterfly as a threatened species.”
- Emma Pelton (Xerces Society): emphasized that, for the second consecutive year, the population remains at historic lows.
Both experts agree that only large-scale collective efforts can prevent the species’ collapse.
Ecological and cultural importance
Monarch butterflies fulfill vital roles:
- Pollination: they transport pollen and contribute to the reproduction of wild plants and agricultural crops.
- Bioindicators: they reflect environmental health and the effects of climate change.
- Food chain: they serve as food for birds, spiders, and small mammals.
- Trinational migration: they connect Canada, the United States, and Mexico in a unique conservation phenomenon.
- Cultural and tourist value: in Mexico, their arrival coincides with the Day of the Dead, where they are seen as souls of ancestors, generating sustainable tourism.
Urgent measures
Including the monarch in the list of threatened species would allow:
- Coordinating federal research and resources.
- Involving government agencies, native tribes, conservation organizations, and private landowners.
- Promoting policies to reduce pesticides and restore habitats.
The monarch butterfly is much more than an insect: it is an ecological and cultural symbol of North America. Its conservation is crucial for the balance of ecosystems and biodiversity.
The slight rebound in 2025 should not obscure the reality: the species remains at historic lows and needs immediate protection.
