Bats use echolocation to find prey
Bats can see about as well as humans.
However, they are nocturnal --- which means they are active at night --- and think about how well you can see at night.
(Read about nocturnal animals in Iowa.)
Without a light, can you see a mosquito? You might feel it bite you, but you sure wouldn't see it coming. Without a flashlight, can you find a moth fluttering its wings? We sure can't.
(We bust some common bat myths here.)
But bats still have to hunt, even when they can't see in the dark. So they use something called echolocation.
Echolocation is a high-frequency system similar to sonar --- like what a fisherman might use to see where fish are at underwater. Bats call in a pitch too high for adult humans to hear as they fly and listen to the returning echoes to build a sound map of their surroundings.
The animals can tell how far away something is by how long it takes the echo to return.
Different species of bats have different frequency ranges for echolocation, depending on their environment and what prey they eat. The species can be identified by its call using a bat detector. In fact, bats can be classified as shouting bats and whispering bats. Common bats in northwest Iowa --- big brown and little brown bats --- are shouting bats, because they make sounds at 110 decibels, about the same as a smoke alarm, because they hunt in open spaces. Whisperers usually hunt in more enclosed areas, such as forests.
Remember though, we can't hear bats hunt. Bat sounds, like from this big brown bat, that can be heard by humans are not echolocation sounds. Echolocation is a frequency too high for humans to hear.