Invertebrates

Monarch Butterfly Migration and Milkweed Loss

Monarch butterfly populations have declined by over 80% due to milkweed loss, habitat degradation, and climate change disrupting migration cues.

Key Facts

Monarchs migrate up to 4,800 km between Canada and Mexico annually
Milkweed is the only plant monarch caterpillars can eat
Herbicide-resistant crop systems have eliminated milkweed from millions of acres
Overwintering sites in Mexican fir forests have been reduced by logging
Eastern monarch populations declined from 1 billion in the 1990s to under 100 million

Welfare Considerations

While individual butterfly welfare is uncertain, population-level decline represents loss of a remarkable migration system evolved over millions of years. Caterpillars that fail to find milkweed die of starvation, and climate disruption may misalign migration timing with nectar availability. Habitat restoration is both a conservation and welfare-relevant intervention.

What You Can Do

Plant native milkweed species in your garden to support monarch populations
Avoid pesticides on milkweed and butterfly garden plants
Support organizations working to restore monarch habitat corridors
Advocate for milkweed-friendly farming practices and conservation easements
Learn about monarch migration to appreciate and share the urgency of their decline