The Incredible Journey of the Butterflies (Blu-ray)

Every year, 100 million monarch butterflies set off on an incredible journey across North America. These beautiful creatures fly 2,000 miles to reach their remote destination: A tiny area high in the mountains of Mexico. Yet scientists are still puzzling over how the butterflies achieve this tremendous feat of endurance-and how, year after year, the monarchs navigate with such hair's-breadth precision.

The Incredible Journey of the Butterflies (Blu-ray)