Passive acoustic monitoring reveals group ranging and territory use: a case study of wild chimpanzees (Pan troglodytes)

摘要

Background: Assessing the range and territories of wild mammals traditionally requires years of data collectionudand often involves directly following individuals or using tracking devices. Indirect and non-invasive methods ofudmonitoring wildlife have therefore emerged as attractive alternatives due to their ability to collect data at largeudspatiotemporal scales using standardized remote sensing technologies. Here, we investigate the use of two noveludpassive acoustic monitoring (PAM) systems used to capture long-distance sounds produced by the same species,udwild chimpanzees (Pan troglodytes), living in two different habitats: forest (Taï, Côte d’Ivoire) and savanna-woodlandud(Issa valley, Tanzania).udResults: Using data collected independently at two field sites, we show that detections of chimpanzee sounds onudautonomous recording devices were predicted by direct and indirect indices of chimpanzee presence. At Taï, theudnumber of chimpanzee buttress drums detected on recording devices was positively influenced by the number ofudhours chimpanzees were seen ranging within a 1 km radius of a device. We observed a similar but weaker relationshipudwithin a 500 m radius. At Issa, the number of indirect chimpanzee observations positively predicted detections ofudchimpanzee loud calls on a recording device within a 500 m but not a 1 km radius. Moreover, using just seven monthsudof PAM data, we could locate two known chimpanzee communities in Taï and observed monthly spatial variation inudthe center of activity for each group.udConclusions: Our work shows PAM is a promising new tool for gathering information about the ranging behavior andudhabitat use of chimpanzees and can be easily adopted for other large territorial mammals, provided they produceudlong-distance acoustic signals that can be captured by autonomous recording devices (e.g., lions and wolves).udWith this study we hope to promote more interdisciplinary research in PAM to help overcome its challenges,udparticularly in data processing, to improve its wider application.