The use of acoustical cues for prey detection by the Indian False Vampire Bat,Megaderma lyra

Summary

• 1. The response of the echolocating bat,Megaderma lyra, was tested to different kinds of prey in an outdoor cage. The bats caught larger flying insects (moths, beetles, grasshoppers, and cockroaches) on the wing and also picked up arthropods (solifugid spiders, beetles and cockroaches) and small vertebrates (mice, fishes, frogs and geckoes) from the ground. After touching the prey with the muzzle, the bats were able to differentiate between species. Scorpions and toads were not taken byM. lyra.

• 2. In lighted and in dark conditions,M. lyra detected and caught prey only when it moved. Dead frogs briskly pulled over the floor were also detected and caught, whereas stationary dead frogs were disregarded by the bats (Table 1).

• 3. When dead frogs were pulled over the watered surface of a glass plate to eliminate noises by motion, the motion no longer alarmed the bats. From the results of these experiments it was concluded thatM. lyra detects prey on the ground by listening to the noise of the moving target only, and not by echolocation (Table 1 C, Fig. 1). Furthermore,M. lyra were not attracted by frog calls.

• 4. M. lyra differentiated between palatable frogs and non-palatable toads only after touching the prey with the muzzle.

• 5. Experiments with freshly killed frogs coated with toad secretions or covered with toad skins indicate thatM. lyra differentiates between frogs and toads by chemical means. There was no evidence that these prey were differentiated by means of echolocation.