Pole Positioning

Help, Siri! I need directions to my house – AGAIN!!

This is Sandra Tsing Loh with the Loh Down on Science.

How did we ever navigate without our GPS friends? But birds ALWAYS find their way home! What’s their secret?

Enter Joe Wynn and colleagues at Oxford and University of Oldenburg. 

To crack the birdie GPS, they analyzed nearly eighty years of migration data of the reed warbler. Every year, their home base location shifts slightly- by around five miles. What ALSO shifts slightly? Earth’s magnetic field! 

So the researchers compared the shifts to see if they match up. Bingo! The warblers appeared to follow something called the magnetic “dip angle.” The angle changes depending how far north or south you are. In the northern hemisphere, it causes compass needles to point downward!

The researchers theorize that the warblers harness this sixth sense by learning the feeling of their home’s unique dip angle. On the return trip, they would just fly back the direction they came from until they felt it again! 

Now, the big magnet I’M always headed towards? The fridge.

Reference: Wynn, J., Padget, O., Mouritsen, H., Morford, J., Jaggers, P., Guilford, T. Magnetic stop signs signal a European songbird’s arrival at the breeding site after migration. Science 375, 6579 (2022). DOI: 10.1126/science.abj4210