Good Question: How Do Birds Know Where To Migrate?

MINNEAPOLIS (WCCO) - As the weather gets colder, birds start heading south for the winter.

Ducks and geese fly thousands of miles, often to very specific locations.

We can rely on a map or a compass or even a GPS with a robotic, monotone voice to tell us where to go.

Birds have to rely on something else.

"It's a huge topic, but it's fascinating. It is really fascinating," said Dr. Julie Ponder.

Dr. Ponder is with The Raptor Center at the University of Minnesota.

"They do have a built-in ability to navigate," said Dr. Ponder.

Dr. Ponder said different species of birds have different ways of navigating.

But all migrating birds, over time, develop a mental map, allowing them to follow waterways and landmarks.

The sun and the stars also help.

"Some species are diurnal migrants and they navigate by the sun. Other species migrate at night and by stars," said Dr. Ponder.

Peregrine falcons need the sun's thermal energy to help them migrate more than 6,000 miles south--from Minnesota to Argentina.

For other species there's a different force involved.

"They have an ability to sense a magnetic field and actually some birds are thought to be able to see magnetic fields," said Dr. Ponder.

Some birds, like pigeons, actually have magnetic mineral in their brains which allows them to fly towards the Earth's north and south magnetic poles.

Ducks and geese mostly fly to southeastern states. Turkey vultures head southwest.

Migration is all about food, which some species can't find much of during a Minnesota winter. But there's a reason they always come back.

"If they come back up here they have a longer day for feeding their young. So reproduction is better. Those long Minnesota days during our warm-weather months allows geese to bring back a lot of food to their young," said Dr. Ponder.

Some species don't leave during the winter, and that's because they have food here--so they stick around.

We are in the heart of the migration season right now.

And actually, some bird species start heading south in August.

Some come back as early as March.