Monarch Butterfly Migration and Welfare

Monarch butterfly populations have declined by 80% over 30 years due to milkweed loss, pesticides, and habitat fragmentation along migration routes.

Key Facts

Eastern monarch butterflies migrate up to 4,800 km from Canada to Mexican overwintering sites each fall
Milkweed is the only plant on which monarch caterpillars can feed and survive
Herbicide-tolerant crop systems have eliminated milkweed from over 165 million acres of US agricultural land
Neonicotinoid pesticides kill monarchs directly and reduce milkweed quality for caterpillar nutrition
Mexico overwintering sites have declined from 18 hectares in 1996 to under 3 hectares in recent years

Welfare Considerations

While butterfly sentience is uncertain, the precautionary welfare principle applies at the scale of hundreds of millions of individuals experiencing habitat loss, pesticide exposure, and disrupted migration. The conservation case for monarch protection is also strong and welfare and conservation interventions align perfectly in this case.

What You Can Do

Plant native milkweed species in your garden or on your property to support monarch breeding habitat
Avoid neonicotinoid pesticide use on milkweed and flowering plants that support monarch nutrition
Donate to Journey North and other monarch monitoring and habitat restoration organizations