Monarch butterflies face existential threats from habitat loss, pesticides and climate change that have reduced populations by 80%, with welfare implications across their remarkable migration.
While insect welfare is debated, monarchs show navigation capacity, learning, and physiological stress responses that suggest some form of sentience. The mass die-offs from cold snaps in overwintering sites, dehydration during migration, and starvation from milkweed loss represent potential suffering at enormous scale. Conservation of monarch habitat is simultaneously a biodiversity, ecosystem services, and potentially a welfare issue of vast scope.