The reasons why animals migrate – more food, better climate, and
safer places to raise young – may seem obvious, but how they do
it is an enduring mystery. Bird banding projects have
demonstrated again and again that, from generation to
generation, birds migrate to the precise locations that their
ancestors selected. For many species, the journey is so well
orchestrated that the traveling birds can be found at the same
spot on the map, on the same day, from year to year. Researchers
have discovered that the gradual shortening of the length of day
as fall approaches triggers hormonal changes in birds that tell
them that it’s time take flight. It makes sense that this type
of reliable external cue would signal when to go, but how do
they know where to go? And how do birds manage to not get lost
when winging their way across vast expanses of open ocean or
unbroken forest? It might be in their DNA. Some young songbirds
take their maiden migration flight by themselves, and they still
make a beeline to the same win