Spatial variation in black-headed night monkey (Aotus nigriceps) vocalizations

Abstract

We would like to thank the Amazonian Conservation Association (ACA), Villa Carmen Biological Station, and 24Manu Learning Center (CREES) staff for hosting us, clearing trails, and providing valuable insight into location and 25 behavior of groups. We are indebted to students and staff from the School for Field Studies who assisted with data 26 collection and logistics. We carried out data collection in accordance with the legal requirements of Peru, and with 27 permission of the Amazon Conservation Association and CREES. 28 Abstract 29Quantitative acoustic analysis has been used to decipher individual differences, population structure, and taxonomic 30 diversity in numerous primate species. We previously described three distinct call types in wild Aotus nigriceps, and 31 now assess acoustic differences in two of these call types between social groups and spatially distinct populations. 32Acoustic parameters for both analyzed call types exhibited significant variability between groups. Similarly, 33 geographically distant field sites were acoustically distinct from one another. Several groups also used a variation of 34 a common call: a triplet Ch Ch instead of a duplicate. Other groups made use of ultrasonic frequencies which have 35 not previously been reported in Aotus. Our results suggest that Aotus nigriceps exhibits substantial acoustic 36 variability across sites that could potentially be useful for taxonomic classification, although additional 37 geographically distant populations still need to be sampled. The possibility of individual signatures also exists and 38 will require recording vocalizations from known individuals. 39