The migratory monarch butterfly endemic to North America has been categorized as an endangered species by the International Union for Conservation of Nature.
Why it matters: The monarch's native population has shrunk between 22% and 72% over the past decade. Its decline is largely due to climate change, deforestation and pesticide use, which kills the milkweed the monarchs feed on, the IUCN said Thursday after adding the butterfly to its "red list" of threatened species for the first time.
