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.
butterflies are born knowing everything they need to survive,
so we look on with wonder:
do the monarchs know when to go to Mexico?
do they know which way to fly?
fast, how far, and how high
do they travel?
how do they know when they have arrived--at
a small speck on the planet where none has ever been before?
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.