Stationary prey insures life and moving prey ensures death during the hunting flight of gleaning bats

Abstract

While flying, the microchiropteran. bats emit brief sounds of high frequencies (15-200 kHz) through the i mouth or the nostrils and listen to the echoes reflected from obstacles and prey. The information from the echoes provides the bats an auditory representation of their surroundings with much precision. It is known that sympatrically living echolocating bat species search for prey at different foraging zones. Their audition and structure of the emitted sound signals are adapted to the specific foraging areas and hunting behaviour. A few species of bats use the foraging strategy of gleaning, i.e. capturing prey from the ground and other surfaces including water. Most of the gleaning bats are carnivorous. They use the noise associated with the movement of the prey as the principal cue to detect them on the ground without using echolocation. They use echolocation while capturing prey in the air or on water surface. However, the pattern of echolocation is not similar to the typical pattern shown by other microchiropterans. Normally the hearing sensitivity of the bats is neurologically tuned to the high frequencies of their echolocation calls which vary from species to species. In addition, the ears of gleaning bats are more sensitive to the low frequency noise (5-20 kHz) created by , the movement of the prey. Passive listening to the prey-generated noise might be more economical, by collecting available information through the ears, without using echolocation. Such passive method of prey detection is also used by other echolocators like killer whales.