Bats are a fascinating group of animals.
Of the some 900 species of bats, more than half rely on echolocation to detect obstacles in flight, find their way into roosts and forage for food. A few species, though, click their tongues. These noises resemble the sounds made by hitting two round pebbles together. Some bats have specialized structures for emitting echolocation calls. Most bats produce a complicated sequence of calls, combining CF and FM components.