PREY DETECTION, DIETARY NICHE BREADTH, AND BODY SIZE IN BATS - WHY ARE AERIAL INSECTIVOROUS BATS SO SMALL

Prey detection by echolocation limits the maximum size of aerial insectivorous bats. One drawback of this system of prey detection is that bats typically detect insects only within a few meters due to the weakness of the echoes reflected from insects and the rapid atmospheric attenuation of high frequency sounds. The short detection range puts a premium on maneuverability for aerial insectivorous bats, and this in itself could restrict their size. The authors' hypothesis is that, contrary to other predators, the prey available to large aerial insectivorous bats is restricted to large prey. Because large insects are relatively rare, aerial insectivorous bats are small because the prey detection system these bats use limits the availability of insects and makes the existence of large species energetically impossible. The flutter-detecting echolocation system used by rhinolophid, hipposiderid and mormoopid bats may be an alternative solution to the prey detection range problem that has allowed these bats to use high-frequency sounds and evolve larger sizes than other aerial insectivorous bats. -from Authors