As the snow (hopefully) stops falling and the weather takes a turn for the better, the snowbirds who made their annual trek south at the start of winter begin to return back north. They use planes, trains and cars allowing their navigation systems, maps, conductors and pilots to lead the way.

Similarly, months ago many real birds began their annual journey south and will soon return back north, but these birds don’t have GPS or a map to show them the way. How exactly do they know which way to fly?

If you were trying to navigate your way in a particular direction in the wild without the use of electronics, what would you use?

Exactly. A compass.

Well as it turns out, scientists now believe that birds may use this very navigation method as well. No, I’m not saying you’re not noticing the birds ahead of you in the checkout line at Walmart or Cabela’s purchasing their handheld compass, but rather, birds may have an internal compass.

Researchers have identified magnetic compounds in the eyes of certain species of birds which act like a compass.

As a quick reminder, a compass is a device with a piece of magnetic material that aligns with Earth’s magnetic field to point north.

Rather than a magnetic material pointing in a certain direction, scientists from the University of Illinois at Urbana-Champaign believe these compounds may allow birds to “see” Earth’s magnetic fields. This vision would be similar to how a thermal camera allows us to “see” where hot objects are in our environment without touching them. We can then choose to move toward or away from the heat just as birds may choose to move toward or away from north.

Just what are these compounds? (Warning: Really cool science ahead.)

Separate studies from a university in Sweden and a university in Germany found the Cry4 protein molecule to most likely be responsible for this phenomenon. Cry4 is part of a group of molecules called cryptochromes which are located in birds’ eyes and are sensitive to blue light, the kind of light from our electronic devices that mess with our sleep cycles. When hit by light, Cry4 breaks into two separate molecules that are each magnetic.

The direction of the Earth’s magnetic field aligns these two magnetic molecules much like a compass needle. The alignment of these molecules (the direction the bird is facing) determines the type of chemical reaction that occurs in the eye and this chemical reaction is then sent to the bird’s brain as a neurological signal. This signal is then translated into the image the bird sees.

Don’t fully understand? That’s okay, neither do scientists, as more research is needed to work out many of the details.

So as you look to the skies as the weather warms and see the birds returning north to signal the start of spring, perhaps you’ll have a bit more of an appreciation for their ability to find their way home.

Any comments or questions? Wondering why or how something in the world around you works? Email me at guido.26@osu.edu.