Behaviour 2019
Environmental Effects on Transmission of Individual Signatures in Northern Gray Gibbon Calls
Gabriel A. Bohn1, Abdul H. Ahmad2, Holger Klinck1, Dena J. Clink1. 1Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, New York, United States; 2Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Sandakan Campus, Sandakan, Sabah, Malaysia

Vocal individuality, present in many taxa, can inform understanding of the functions of vocal signals. Previous work has shown that female Northern gray gibbons' calls contain individual signatures. Here we present the results of a playback study at Maliau Basin Conservation Area in Malaysia, in which we broadcast and re-recorded calls from 12 individual females (N=60 calls). We predicted that changes in ambient noise, signal-receiver distance, and time of day would affect the classification accuracy of individuals. We also predicted that different parts of great calls would differentially affect our ability to identify individuals. We found classification accuracy decreased with distance but was not affected by time of day. Furthermore, we found that the introductory part of the great call more effectively transmits individual signatures over distance than the trill portion, which may suggest these different parts of great calls have different functions.  A better understanding of the transmission of individual signatures in gibbon calls should improve our ability to identify individuals during passive acoustic monitoring, aiding conservation efforts.