Ontogeny of vocalization in Jamaican fruit bats with implications for the evolution of echolocation

Abstract

AbstractA long‐standing question in bat biology is if the evolution of echolocation and flight are associated or if they evolved independently, and if so, which evolved first. We seek to use ontogeny as a surrogate for understanding linkages between flight evolution and echolocation in bats. To do this we quantify the onset of recognizable sonar calls in newborn Artibeus jamaicensis and the tempo of growth and development across several different postnatal flight stages. By dropping individuals from a perch beginning on day 1 postpartum, we recorded vocalizations and quantified their flight ability into five developmental stages (flop, flutter, flap, flight and adult). One‐day‐old individuals were capable of emitting sonar‐like frequency‐modulated (FM) calls during free‐fall that were not significantly different from adult sonar calls in high and low frequency (kHz). However, bandwidth (kHz) did increase significantly with age as did sweep rate (kHz ms−1), whereas call duration significantly decreased. Few bats older than 18 days emitted communication calls as they fell and measured parameters of communication calls did not change significantly with age. Our data support the hypothesis that communication and sonar calls are discrete and independently derived at birth and thus have different evolutionary pathways as well.