Abstract # 7863 Event # 155:

Scheduled for Sunday, August 27, 2017 09:45 AM-10:00 AM: (National Ballroom Salon A) Oral Presentation


L. A. Isbell1,2, L. R. Bidner1,2, M. C. Crofoot1,2, A. Matsumoto-Oda2,3,4 and D. R. Farine1,2,5,6
1Department of Anthropology, University of California, Davis, CA 95616, USA, 2Mpala Research Centre, Kenya, 3Graduate School of Tourism Sciences, University of the Ryukyus, Japan , 4Graduate School of Environmental Studies, Nagoya University, Japan , 5Department of Collective Behaviour, Max Planck Institute for Ornithology, Konstanz, Germany, 6Department of Biology, University of Konstanz, Germany

All anthropoid primates are considered strictly diurnal except for owl monkeys (Aotus). New technology has shown, however, that some anthropoids also engage in nocturnal activity. Here we examine the extent to which vervets (Chlorocebus pygerythrus) and olive baboons (Papio anubis) are active at night. We deployed GPS collars with tri-axial accelerometers on 12 vervets in five groups and six olive baboons in four groups. For seven months their locations were recorded every 15 min, and their activity levels, for 3 sec every min. We also employed remote cameras aimed at terrestrial movement at seven sleeping sites. Travel was detected on 0.4% of 2029 vervet-nights involving three vervets and 1.1% of 1109 baboon-nights involving five baboons. Since no monkeys were photographed on the ground at night, nighttime travel was likely arboreal. Baboons traveled on significantly more nights than vervets (χ2 = 4.33, p = 0.04). During the night, vervets were active 13% of the time, and baboons, 15%. Activity varied little throughout the night and was unaffected by moon phase. We suggest that their low nocturnal activity may be related to living near the equator with consistent 12-hr days, in contrast to anthropoids that are more nocturnally active. Since anthropoids are thought to have evolved in northern latitudes, with later dispersal to tropical latitudes, our results may have implications for understanding the evolution of anthropoid diurnality.