A new study has revealed that bats avoid collisions by following certain set of "traffic rules" laid down by them while trawling for food at high speed.
Dr Marc Holderied of Bristol's School of Biological Sciences studied pairs of Daubenton's bats (Myotis daubentonii) foraging low over water for stranded insects at a site near the village of Barrow Gurney in Somerset, UK.
These flying mammals perceive their surroundings by emitting loud and high-pitched biosonar calls and listening for the returning echoes. Because bat biosonar imaging was much sparser in information than vision, Dr Holderied was able to accurately measure the biosonar calls of the interacting bats and then calculate what each of the individuals perceived.
The results indicated that bats obey their own intriguing set of "traffic rules," they chase each other, perform tandem turns and even slow down to avoid collision.
Together with Dr Luca Giuggioli from the Bristol Centre for Complexity Sciences and Thomas McKetterick from the Department of Engineering Mathematics, Dr Holderied modelled the bats' biosonar view of their surroundings during these interactions and discovered that one simple trick suffices to create all the bats' interactive behaviours.
They swap leader-follower roles and perform chases or coordinated manoeuvres by copying the heading a nearby individual was using up to 500 milliseconds earlier.