Two-toned echolocation calls from Molossus molossus in Cuba

Abstract

Molossus molossus from Cuba uses narrowband search signals that typically are emitted in a series of pairs with a signal of lower frequency (mean peak frequency = 34.1 kHz) followed by a signal of higher frequency (39.7 kHz). Both frequencies fall into the most sensitive region of a previously published audiogram of M. molossus. Because there is no overlap in frequency between the two signals of one pair, pairing may allow the bat to process echoes of one call while emitting the second call. This would extend the duty cycle of temporal scanning by using two separate frequency channels in its auditory system to analyze calls.