Bats don't see in the dark, the don't even have eyes. The have what is called echolocation. Echolocation is the general method of locating objects by determining the time for an echo to return and the direction from which it returns, as by radar or sonar.
Okay. Bats do have eyes. Some, like the Vampire bat can see in the dark. The Vampire bat has echolocation, but it isn't as developed as some other bat species, so they don't rely on it exclusively. They land near their victim, anyway, to watch and make sure it is asleep or unable to attack the bat in defense. Cows are ideal, because they usually fill both criterion. Cows don’t have arms and hands with which to reach out and grab or hit the bat, and they are usually sleeping at night when these vampires are out looking for blood.
Vampire bat Diurnal fruit bats don’t rely on echo location, either, but since they aren’t nocturnal I won’t go into detail about them, as that is not what you asked.
Flying fox (a type of fruit bat) It is true, however, most bats do have highly developed echolocation and poor eyesight, therefore, rely almost exclusively on their echolocation rather than visual acuity. For more details about echolocation, go to… http (colon) (double slash) www (dot) tigerhomes (dot) org (slash) animal (slash) the-bat-radar-vision (dot) cfm