The results appeared in the Science on 20 November . "This is probably the clearest demonstration of the neural pathways responsible for magnetic processing in any animal," says Eric Warrant, a sensory biology researcher at the University of Lund in Sweden. Studies have suggested that various animals, including turtles, trout and robins, can sense the direction and strength of magnetic fields, although the evidence has sometimes been contested - and the mechanisms have remained controversial.
The problem of how migrating birds and homing pigeons navigate still remains unsolved in spite of intensive research efforts in the past few years. Over twenty years ago, Gustav Kramer suggested that in order to fly from an unfamiliar place to a geographically distant home site, a bird would need information analogous to a map (on which to read its own position and that of home), and a compass (to choose the appropriate direction indicated by the map). It is now well established that both migrating song birds and homing pigeons (on which much of the experimental work is done) have up to three types of compass-based on the Sun's azimuth, star patterns and the resultant of the Earth's magnetic field , but the nature of the map remains elusive ... [T]he big remaining mystery surrounding the magnetic compass, is how the bird's sensory system detects the Earth's magnetic field.