From www.youtube.com - April 27, 2012 2:35 PM

Scientists at Baylor College of Medicine have discovered 53 neuron cells in the small bird's brain that may actually make up a biological "GPS system," each with its own characteristic response to the Earth's magnetic field. The combined data of each neuron's reaction to its north-south and up-down orientation gives the pigeon not only an accurate compass heading, but may also give it coordinates on a mental map.