40 years ago, Prof. Dr. Wolfgang Wiltschko was the first to prove that migrating robins use the Earths magnetic field to direct themselves during migration. Their magnetic sensor showed them the course of the field lines of the Earths magnetic field. This produces an inclination compass that reacts to the inclination of the Earths magnetic field to the surface of the Earth, thus distinguishing between pole-wards (the side on which the field lines incline downwards) and equator-wards (the side on which they incline upwards). The inbuilt compass is additionally finely tuned to the field strength of the Earths local magnetic field, but can also be flexibly adapted to other field strengths that the birds encounter in the course of migration. Since that time a compass of this kind has been found in more than 20 species of birds, the majority of them being those songbirds that undertake annual migration. An international working group under the direction of Wolfgang und Roswitha Wiltschko of Frankfurt University has now succeeded in demonstrating the presence of a magnetic sense of direction in domestic chickens as well.
For this purpose, newly hatched chicks were imprinted on a red ball which they from then on regarded as their mother. The researchers then hid the ball behind one of four screens, and taught the chickens by intensive training that the mother was always behind the screen that was in the northerly direction. To demonstrate that the chicken senses this compass point by means of its magnetic sense of direction, the researchers set up an artificial magnetic field in an easterly direction and the chickens did actually seek their mother behind the screen that lay to the east.
Further experiments showed that the chickens magnetic sensor functions very similarly to that of the robin. It also reacts to the inclination and the local field strength of the Earths magnetic field. The magnetic sensor is probably situated in the eye, since the b
Contact: Wolfgang Wiltschko
Johann Wolfgang Goethe-Universitt Frankfurt