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

Abstract

BackgroundAssessing the range and territories of wild mammals traditionally requires years of data collection and often involves directly following individuals or using tracking devices. Indirect and non-invasive methods of monitoring wildlife have therefore emerged as attractive alternatives due to their ability to collect data at large spatiotemporal scales using standardized remote sensing technologies. Here, we investigate the use of two novel passive acoustic monitoring (PAM) systems used to capture long-distance sounds produced by the same species, wild chimpanzees (Pan troglodytes), living in two different habitats: forest (Taï, Côte d’Ivoire) and savanna-woodland (Issa valley, Tanzania).ResultsUsing data collected independently at two field sites, we show that detections of chimpanzee sounds on autonomous recording devices were predicted by direct and indirect indices of chimpanzee presence. At Taï, the number of chimpanzee buttress drums detected on recording devices was positively influenced by the number of hours chimpanzees were seen ranging within a 1 km radius of a device. We observed a similar but weaker relationship within a 500 m radius. At Issa, the number of indirect chimpanzee observations positively predicted detections of chimpanzee loud calls on a recording device within a 500 m but not a 1 km radius. Moreover, using just seven months of PAM data, we could locate two known chimpanzee communities in Taï and observed monthly spatial variation in the center of activity for each group.ConclusionsOur work shows PAM is a promising new tool for gathering information about the ranging behavior and habitat use of chimpanzees and can be easily adopted for other large territorial mammals, provided they produce long-distance acoustic signals that can be captured by autonomous recording devices (e.g., lions and wolves). With this study we hope to promote more interdisciplinary research in PAM to help overcome its challenges, particularly in data processing, to improve its wider application.Electronic supplementary materialThe online version of this article (doi:10.1186/s12983-016-0167-8) contains supplementary material, which is available to authorized users.

Passive acoustic monitoring as a law enforcement tool for Afrotropical rainforests

“…Simultaneously, the data can provide insight on the occurrence and seasonal ranging of cryptic wildlife species (eg Kalan et al . ).…”

What animals do not do or fail to find: A novel observational approach for studying cognition in the wild

“…For example, some plant species that rely on seed dispersal can substantially increase the amount of scent emitted from ripe fruit, such that primates can distinguish them more easily from unripe fruits, and likely detect them from larger distances. One of the most frequently used methods in primatology to rule out the use of sensory cues is to estimate the distances at which the study species can perceive food or other animals . Being primates ourselves sometimes helps to make these distances more realistic.…”

“…When collecting behavioral data on wild animals, advanced technologies that enable camera trap or audio triangulation methods are increasingly applied. 99,[118][119][120] Such technological advances enable us to study behavior (through observations or experiments) in a highly noninvasive manner and to avoid the risks associated with habituation, such as disease transmission. 121 Such approaches make it possible to study wild animals without the need for long-term commitment to protecting the habituated animals from poachers.…”

“…One of the most frequently used methods in primatology to rule out the use of sensory cues is to estimate the distances at which the study species can perceive food or other animals. 36,69,85,118,149 Being primates ourselves sometimes helps to make these distances more realistic. On an olfactory level, humans, similar to nonhuman primates are sensitive to isoamyl acetate, the major component in a large variety of fruit odours.…”

Listening and watching: Do camera traps or acoustic sensors more efficiently detect wild chimpanzees in an open habitat?

“…CT studies on chimpanzees have been conducted to study uncommon behaviour, for example stone throwing (Kühl et al, ) and crab hunting (Koops et al, ), but also for abundance and density estimation (Cappelle, Després‐Einspenner, Howe, Boesch, & Kühl, ; Després‐Einspenner, Howe, Drapeau, & Kühl, ) among others. Only a few studies have employed PAM with chimpanzees; those have focused on group ranging and territory use (Kalan et al, , ) and temporal patterns of vocalizations (Piel, ).…”