Sense
Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.
Reverse migration (birds)
This is a technique used to track animals with a transmitter and receivers. A miniature transmitter is attached to the subject animal and this transmitter emits a very high frequency (30-300 MHz) which can be picked up with one or more receivers. For studying the moment behaviour of birds in a migration hotspot south-west of Sweden called Falsterbo near Falsterbo bird observatory three receivers were used to triangulate and track the birds.
Ringing birds is when a light weight metal band is attach to the foot to not impair movement but stay on the bird with a identification number. This identification number can provide people catching and these birds movement and history with information such as how old they are and where they have been. At the Falsterbo bird observatory these birds are caught with a mist net measured and banded.