1School of Human Evolution and Social Change, Arizona State University, 2Department of Biological Anthropology, University of Cambridge, 3Department of Anthropology, University of California, San Diego, 4Ugalla Primate Project
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The difficulty of observing elusive savanna chimpanzees makes one’s choice of methods decisive. Currently, three main methods are employed to study unhabituated chimpanzees at the site of Issa, Ugalla in western Tanzania: (1) “Listen and Follow”, (2) digital camera traps, and (3) day-long patch vigils. This paper compares these methods over a one-year period to determine which approach results in the greatest number of chimpanzee and other unhabituated mammal sightings. “Listen and Follow” resulted in the highest chimpanzee encounter rate, followed by camera traps, with some cameras yielding more encounters than others; patch vigils had the lowest rate of chimpanzee sightings. However, the encounter rate of non-chimpanzee fauna was higher for patch vigils than for camera traps. Differences in encounter rates are likely due to biases in how these methods are employed: “Listen and Follow” is used in areas where chimpanzees are assumed to be based on previous sightings or vocalizations; camera traps are located throughout the study site, but placed near animal trails; patches are randomly selected, distributed in areas that may or may not be near trails or in locations known to be frequented by chimpanzees. Results indicate that a method such as “Listen and Follow” is more informative for a species-specific study, particularly at sites where researchers have an idea where animals are located, and are thus able to direct search efforts. Methods like camera traps and day-long patch vigils, although not commonly used for primatological research, are extremely informative and well suited for community ecology studies.