I’m going to display my nerd banner once again, but I am currently reading the Song of Ice and Fire series. While the books are placed firmly in the realm of fantasy, there are few elements that echo how life was lived in the middle ages, namely using birds to carry messages quickly over long distances. I don’t know about you, but that baffles me just as much as the inner workings of the internet.

It’s taken a couple hundred years, but researchers at the U.S. Geological Survey think they’ve discovered how it’s done. Pigeons can hear very low frequencies, as low as .1 Hz. And it just so happens that the Earth emits very low sound waves, which vary according to topography. Researchers also noticed that during European homing pigeon races, the birds would get disoriented when Concord jets were flying nearby, creating sonic booms and disturbing the low frequencies. When scientists put all these factors together, they agreed that pigeons using sound to navigate was a pretty reasonable theory.

Homing pigeons can navigate at any time of day and any time of year, so using any celestial bodies to chart their course would have to be ruled out. But so long as there are no major disturbances, the infrared frequencies from the Earth are pretty much consistent. Researchers believe that the pigeons do have a map in their heads, but that map is made of sound frequencies. Occasionally strong winds or storms can throw the birds off course, but so long as they’re female, they have no problem stopping and asking for directions.