Tracks of homing pigeons that were trained to navigate over 20km back to their aviaries in Southern Germany. Some pigeons were treated with clodronate to deplete macrophages. Untreated pigeons (white) navigated successfully home on sunny and overcast days. Clodronate-treated pigeons also navigated successfully home on sunny days (orange), but could not navigate home on overcast days (blue). Credit: Max Planck Institute of Animal Behavior
How pigeons fly hundreds of kilometers and still find their way home has long fascinated people. Now, researchers say a surprising answer may be hidden, not in the brain or eyes of birds, but in the liver.
