There has been a superb paper in Frontiers in Zoology, that describes the landing patterns of birds. The paper writer is also an amazing feat of data collection. The team of Hynek Bruda noted landings of nearly 14 species of birds and observed nearly 15,000 birds. They noticed that the birds always landed in the direction of the earth’s magnetic field. This is incredible because it serves to align all the birds in one direction and may help in collision avoidance. The sensors in birds are located in two places:
- Magnetic iron oxide located in their beak and/or inner ear.
- Magnetic sensitive reaction occurring somewhere in their eye that enables them to see the magnetic field.
This paper is worth a read but also implies that if other biological species like homing pigeons use the same magnetism. However, in pigeons they supplement magnetism with other sensors since in homing pigeons the smell is very important to homing.