@article {53243, title = {Temporal adjustment of short calls according to a partner during vocal turn-taking in Japanese macaques}, journal = {Current Zoology}, year = {2018}, month = {Mar-10-2019}, abstract = {

Turn-taking is a common feature in human speech, and is also seen in the communication of other primate species. However, evidence of turn-taking in vocal exchanges within a short time frame is still scarce in nonhuman primates. This study investigated whether dynamic adjustment during turn-taking in short calls exists in Japanese macaques Macaca fuscata. We observed exchanges of short calls such as grunts, girneys, and short, low coos during social interactions in a free-ranging group of Japanese macaques. We found that the median gap between the turns of two callers was 250\ ms. Call intervals varied among individuals, suggesting that call intervals were not fixed among individuals. Solo call intervals were shorter than call intervals interrupted by responses from partners (i.e., exchanges) and longer than those between the partner\’s reply and the reply to that call, indicating that the monkeys did not just repeat calls at certain intervals irrespective of the social situation. The differences in call intervals during exchanged and solo call sequences were explained by the response interval of the partner, suggesting an adjustment of call timing according to the tempo of the partner\’s call utterance. These findings suggest that monkeys display dynamic temporal adjustment in a short time window, which is comparable to turn-taking in human speech.

}, keywords = {primate, rhythm, turn-taking, vocalization}, issn = {1674-5507}, doi = {10.1093/cz/zoy077}, url = {https://academic.oup.com/cz/advance-article/doi/10.1093/cz/zoy077/5132690}, author = {Katsu, Noriko and Yamada, Kazunori and Okanoya, Kazuo and Nakamichi, Masayuki} } @article {52882, title = {Temporal patterns of chimpanzee loud calls in the Issa Valley, Tanzania: Evidence of nocturnal acoustic behavior in wild chimpanzees}, journal = {American Journal of Physical Anthropology}, volume = {166}, year = {2018}, month = {Jan-07-2018}, pages = {530 - 540}, abstract = {

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.

}, keywords = {great ape, pant hoot, passive acoustic monitoring, vocalization}, doi = {10.1002/ajpa.v166.310.1002/ajpa.23609}, url = {http://doi.wiley.com/10.1002/ajpa.v166.3}, author = {Piel, Alex K.} }