The traditional thinking tells that bats come at night because they can see clearly in the dark but , this is however a wrong notion. Experiment done on bats tells that bats can fly comfortably even if its eyes are covered by some opaque material. This was possible because they use sound rather than sight to navigate. This method of navigation is know as echolocation and it is similar in principle to the sonar that submarines use to navigate the ocean. Some bats eat fruit, many bats eat insects and vampire bats in the tropics feed on the blood of animals. To search for insects a typical bat will sweep an area with sound, sending out 10 beats per second. When the echoes come back from the prey, such as a fly, the sound pulses increase to more than 25 per second. This gives the bat a better idea of where the fly is moving. As the bat near to its prey, it sends out more and more sound pulses as many as 200 per second. Some bats are so good at echolocation that they can detect and avoid wires as thin as human hairs.
