02806nas a2200181 4500008004100000245013700041210006900178260001600247300001400263490000800277520219800285653001402483653001402497653003202511653001702543100001902560856004502579 2018 eng d00aTemporal patterns of chimpanzee loud calls in the Issa Valley, Tanzania: Evidence of nocturnal acoustic behavior in wild chimpanzees0 aTemporal patterns of chimpanzee loud calls in the Issa Valley Ta cJan-07-2018 a530 - 5400 v1663 a

Objectives: Much is known about chimpanzee diurnal call patterns, but far less about night-time vocal behavior. I deployed a passive acoustic monitoring (PAM) system to assess 24-hr temporal acoustic activity of wild, unhabituated chimpanzees that live in a woodland mosaic habitat similar to hominin landscapes from the Plio-Pleistocene. A primary aim was to apply findings to our broader understanding to chimpanzee 24-hr activity patterns, and what implications this may have for reconstructing hominin adaptations to similarly hot, dry, and open landscapes. I also tested whether chimpanzees conform to the acoustic adaptation hypothesis, and produce loud calls dur- ing periods of optimal sound transmission.


Methods: Nine custom-made solar-powered acoustic transmission units (SPATUs) recorded con- tinuously for 250 days over 11 months in the Issa Valley, western Tanzania. I complemented acoustic data with environmental data from weather stations as well as behavioral data collected on chimpanzee nest group sizes to assess the relationship between party size and calling.


Results: Chimpanzees called at all hours of the day and night in both wet and dry seasons, and night and day calls exhibited parallel rates/month, although twilight calls were produced signifi- cantly more in the dry, compared to the wet season. Calls were more likely during warmer temperatures and lower humidity. Call rate was positively associated with (nest) party size and counter-calls exhibited no temporal variation in their origins (similar vs. adjacent valleys).


Conclusions: Chimpanzees were acoustically active throughout the 24-hr cycle, although at low rates compared to diurnal activity, revealing night-time activity in an ape otherwise described as diurnal. Chimpanzee loud calls partially, and weakly, conformed to the acoustic adaptation hypoth- esis and likely responded to social, rather than environmental factors. Call rates accurately reflect grouping patterns and PAM is demonstrated to be an effective means of remotely assessing activ- ity, especially at times and from places that are difficult to access for researchers.

10agreat ape10apant hoot10apassive acoustic monitoring10avocalization1 aPiel, Alex, K. uhttp://doi.wiley.com/10.1002/ajpa.v166.302724nas a2200277 4500008004100000022001300041245009200054210006900146260001600215300001400231490000800245520190000253653001502153653001802168653001602186653001302202653002902215653001302244653002002257100002202277700002002299700002202319700002202341700001702363856006602380 2017 eng d a0003347200aGestural development of chimpanzees in the wild: the impact of interactional experience0 aGestural development of chimpanzees in the wild the impact of in cJan-12-2017 a271 - 2820 v1343 a

To understand the complexity involved in animal signalling, studies have mainly focused on repertoire size and information conveyed in vocalizations of birds and nonhuman primates. However, recent studies on gestural abilities of nonhuman primates have shown that we also need a detailed understanding of other communicative modalities and underlying cognitive skills to grasp this phenomenon in detail. Here, we thus examined gestural signalling of chimpanzees, Pan troglodytes, living in two communities in the wild (Kanyawara, Uganda; Taï South, Co^te d'Ivoire) with a special focus on the influence of the social environment on signal development. Specifically, we investigated to what extent specific social factors, namely behavioural context, interaction rates and maternal proximity, affect gestural production (i.e. gesture frequency, sequences and repertoire size). We used a combination of video recordings and focal scans obtained from 11 infants aged between 9 and 69 months during 1145 h of observation throughout two consecutive field periods. Overall, we found that social play was the context in which the highest number of gestures occurred. While gesture frequency and repertoire size increased with higher inter- action rates with nonmaternal conspecifics and the number of previous interaction partners, no effect was found for interaction rates with mothers. Our results thus imply that infants of social mothers may have a head start in life. Moreover, we provide hitherto undocumented evidence for sex differences in gestural signalling, which may reflect the differential importance of early socialization for chimpanzee males and females. Gestural development thus relies heavily on interactional experiences with con- specifics, which adds support for gestural acquisition via the learning mechanism of ‘social negotiation’ in great apes.

10achimpanzee10acommunication10adevelopment10agestures10ainteractional experience10aontogeny10aPan troglodytes1 aFröhlich, Marlen1 aMüller, Gudrun1 aZeiträg, Claudia1 aWittig, Roman, M.1 aPika, Simone uhttp://linkinghub.elsevier.com/retrieve/pii/S000334721630361X