Echolocation

 
Like all mammals, bats have eyes, and certainly use them to see where they are flying at night. Their sight is not good enough however to see in total darkness, or to catch fast-flying insects. Instead of sight they depend on hearing to catch their food, using a system called echolocation, which means locating - or finding - things by echoes.

Bats shout loudly as they fly, sometimes more than ten times in a second, and listen for the echoes that bounce back. The echo returning from a tree is quite different to that from an insect, so a bat knows what is ahead of it in the darkness. They can even recognise their favourite insects.

The bat produces the sound in its voice box or larynx. When the returning echoes - vibrations in the air - reach the bat’s eardrums they are changed to vibrations in the bones in the inner ear which send information to the brain.

In order to give a clear picture the shouts are very high-pitched which is why we cannot hear the bats shouting as they fly around. Young people may hear part of the call, but older people rarely can.