Every fall, a magical event takes place in the animal world. Perhaps traveling over your own head right now--or clustered by the hundreds in a nearby tree--the annual monarch butterfly migration to Mexico is underway. By instinct alone, the butterflies go to the same mountains that their ancestors left the previous spring. Somehow, they find a place in Mexico that they've never seen before.
The butterflies are born knowing everything they need to survive, so we look on with wonder:
How do the monarchs know when to go to Mexico?
How do they know which way to fly?
How fast, how far, and how high do they travel?
And how do they know when they have arrived--at a small speck on the planet where none has ever been before?
Travel with the monarchs this fall as we explore questions like these. In the weeks ahead, we'll see what scientists know about these migration mysteries, and how much more we can learn.