Collision avoidance system

Everybody facing north?   Image courtesy of Charles J Sharp.

Everybody facing north? 

Image courtesy of Charles J Sharp.

Have you ever wondered why a herd of gazelle fleeing from a lion do not end up tripping over one another when a lion races in? There have been a lot of theories on this but none have been put to the test. Now a team has done the gruelling legwork and found these herds are using the planet's magnetic field to coordinate their escape. 

The researchers behind the new work went about the painstaking process of measuring the alignment of hundreds of free ranging roe deer and the compass direction of their escape trajectories after they frightened them. They found that the deer were definitely not randomly aligned along Earth's north-south axis when grazing. More importantly, the deer were much more likely to flee north or south even when the best hiding spots were east or west. You can read more in The Economist article that I wrote on this subject here.