In a first study of its kind, researchers have recorded what's going on in a pigeon's brain during flight.
Writing in the journal Current Biology, researchers at the University of Zurich wanted to know if familiar landmarks could be associated with changes in brain activity.
The exact methods that homing pigeons use to find their way home are still unclear, though there is some evidence that they rely on their sense of smell, the position of the Sun, the Earth's magnetic field and familiar landmarks. This versatility makes them very difficult to study, because even if you're tracking their flight with GPS, it's hard to say what method they rely on at any particular part of the journey.
By fitting pigeons with a very small electroencephalogram, or EEG, which records electrical activity in the brain, and then combining this data with GPS data for flight paths, the researchers we're able to map brain activity onto geographical areas of interest. The pigeons were monitored as they flew from a release sight back to their loft.
They found 2 distinct levels of brain activity - a middle frequency response, which happened when the pigeons paid visual attention to something; and high-frequency activity which seemed to correspond to familiar objects or when additional cognitive processing is going on.
These results means that we can use the record of brain activity to identify areas of importance for pigeon navigation, that we never could have determined from GPS data alone. This gives us real insight into how birds navigate in the real world.
Interestingly, there were a few bits of the journey with unexplained brain activity - places so close to the loft that they weren't needed for navigation. The researchers called this a 'riddle' and one they only solved when they went to visit theses sights - one was a farm and the other a barn. Both contained colonies of feral pigeons, which clearly caught the study pigeons' attention!