The migration patters of animals have long been a source of wonder and awe. From the 6-mile journey of the army ants in the rain forests of Costa Rica, to the 20,000-mile journey of the sperm wale thought the world’s oceans, these animals’ ability to recognize when it’s time to leave and where to go is a source of great fascination. The lessons described, in this chapter, explore what we know about animal migration and what still remains a mystery. 5