The monarch butterfly's iconic 3,000-mile migration is in jeopardy due to habitat loss and extreme weather, prompting scientists and dedicated volunteers to take action. Together, they're working to better understand this annual journey through innovative technology, like attaching tiny sensors to the butterflies to map their paths. Learn more about the challenges facing the monarch: https://on.natgeo.com/4or3H0p Explore the World with National Geographic subscriptions: https://natgeo.com/