Wild Monarch Butterfly Welfare and Migration

Monarch butterflies undertake one of the most remarkable migrations on Earth, but their population has declined by over 80% due to milkweed loss, pesticides, and climate change.

Key Facts

Eastern monarch butterflies migrate up to 4,500 km from eastern North America to overwintering forests in central Mexico
Western monarchs overwinter in coastal California groves and have declined by over 95% since the 1980s
Milkweed is the only plant monarch caterpillars can eat, and it has been largely eliminated from agricultural landscapes by herbicide use
Pesticide exposure including neonicotinoids kills adult monarchs and may impair navigation and reproduction
Climate change is affecting the timing of milkweed emergence relative to monarch breeding migrations
Whether individual butterflies have welfare-relevant experiences is scientifically uncertain, but precautionary considerations apply given the scale of decline
Mass overwintering aggregations of millions of butterflies in Mexican forests are one of the natural world most dramatic wildlife spectacles

Welfare Considerations

The welfare status of individual monarch butterflies is scientifically uncertain, but the collapse of one of the natural world most extraordinary phenomena has conservation and potentially welfare significance at massive scale. From a precautionary perspective, ensuring that butterflies can complete their migrations without pesticide exposure, starvation from milkweed loss, or deforestation of overwintering sites is consistent with caring about animal wellbeing. Planting milkweed and native nectar sources is one of the most tangible individual actions for supporting monarch populations.

What You Can Do

Plant native milkweed species appropriate to your region to support monarch breeding habitat
Avoid or minimize pesticide use in gardens, especially neonicotinoid-containing products harmful to pollinators
Support advocacy organizations campaigning for pesticide regulation that protects monarch migration routes
Donate to conservation programs protecting monarch overwintering forest habitat in Mexico and California
Participate in citizen science monarch monitoring and tagging programs that track population trends