REGULAR PULSE EMISSION IN SOME MEGACHIROPTERAN BATS

We recorded vocalizations of megachiropteran bats, Cynopterus brachyot is, C. horsfieldi, Megaerops ecaudatus and Macroglossus sobrinus as th ey were held in our hands, in a hanging position or moved up and down, simulating flight. All four species produced regular audible tone pul ses with a frequency spectrum of less than 9 kHz (peak at 4-6 kHz). Th e duration of a single pulse varied from 14.9 to 23.6 msec on average among these species. The interpulse interval was between 108.3 and 127 .7 msec. In M. ecaudatus and M. sobrinus, double pulses were occasiona lly emitted, with interpulse intervals averaging 39 msec and 31 msec, respectively. The regular pulse emission may indicate that the bats st udied use sounds to probe space.