Things you didn't know about the bat

Why do bats live in caves?
Why don't they fly into objects at night?

Most bats are nocturnal.
Most bats are nocturnal. They fly and forage for their food (bugs) at night. This means
that they need safe places to sleep during the day. Caves provide the kind of protected
shelter in which bats can thrive. Hanging from the ceiling of a cave, bats are out of reach of most of their enemies. Some of the most successful species of bats live in large cave colonies. Someofthese colonies have millions ofmembers, even up to 20 million!
Carlsbad Caverns in New Mexico once had 7-8 million, but now has about 1 million.

So, why don't bats fly into things at night? They use echolocation to locate food and
avoid obstacles. They have the ability to create and hear noises that humans cannot hear.
The sound waves bounce off of objects and back to the bat, which can then judge the size
and distance of the object. These subsonic noises vary in length and pulse frequency, and
are unique to the individual. Each bat recognizes its own pulse reflections, or "voice," and
uses it to avoid objects and to identify food.

Most bat colonies leave their caves more or less together, in large groups after dark.
Before leaving they fly around inside, preparing for departure. Flying around with
thousands of other bats inside a cave creates a chaotic amount of noise! The bats simply
ignore their personal navigation systems inside the caves. The echolocators are on, but
the bats aren't listening.


If you suddenly appeared in their cave among the flying bats, they would crash into you.
The famous bat expert, Dr. Donald. R. Griffin, called this phenomenon the "Andrea
Doria effect." The Andrea Doria sank when it crashed into another ship out in the middle
of the Atlantic ocean.

When bats are paying attention to their sonar signals, they can navigate without crashing
into things. They can identify and capture food while it is moving. The echolocation
systemis designed to locate very small insects. Most of themare less than a centimeter in
diameter. Compared to a bug, a human being is a very large, slow moving soundreflecting surface. Outside of the cave, the chance of a bat hitting a person is very slim!
There are also bats that fly and hunt for food during the day. They sleep outdoors at night
in trees, under bridges and other locations. Unlike nocturnal bats, they have welldeveloped eyes and poorly developed echolocation.