Chimpanzee Behavioural Ecology
Questions about the behavioural ecology of open-habitat chimpanzees centre on two (potentially related) topics: the social consequences of low population density, and the use of chimpanzee adaptation to arid, open (mosaic) habitats as a model for understanding early hominin adaptation to similar paleoenvironments.
Central to both is the observation that at Issa, chimpanzee population densities are as little as 1/50th of those seen at forested sites. At such low densities, it would be impractical for individuals to patrol territorial boundaries (and make incursions to neighbouring communities) as they are known to do almost everywhere that they are studied.
The role of Issa chimpanzees in informing our understanding of human evolution:
Issa chimpanzees are similar in body size, cranial capacity and overall biology to early (i.e., pre-Homo) hominins, living in an environment similar to that of Ardipithecus and early Australopithecus. To be useful models, we must integrate our observations of chimpanzee behaviour with information from the fossil record. This is one goal of our research.
From August 2018, Issa chimpanzees could be followed from nest to nest, and thus we are only recently poised to test previous theories about their adaptation to this hot, dry, and open habitat. Current projects include investigation of chimpanzee positional behaviour (see here for work led by Rhianna Drummond-Clarke), and for 2020-2021 and with support from the US Fish and Wildlife, Great Ape Conservation fund, we will be looking into chimpanzee responses to annual (grass) fires across the ecosystem and especially how these fires affect chimpanzee food sources. For a recent study on how hominins may have responded to burned areas, please see here.