The first chapter from my PhD thesis on social learning and stone tool use by white-faced capuchins living in Coiba National Park, Panama, is now online! Our study, comparing the coupling of coastal activity to tidal cycles between tool-using and non-tool-using capuchins was published in Royal Society Open Science and can be read here.
On Jicarón island, we have the unique opportunity to compare tool-using and non-tool-using capuchins in the same habitat, because the use of stone tools is incredibly localized. This study focuses on intertidal resources, which capuchins eat with and without tools
We directly compared tool-using to non-tool-using capuchins through two grids of camera traps: one on the tool-using group, and another on the other side of the island on a non-tool-using group. Land animals eating intertidal resources are fascinating, as these valuable foods are only available for a limited period. The timing of low tide may be predictable (to us), but shifts daily. Efficient exploitation is an investment, and tool use might afford higher returns
We found that capuchins on Jicarón show higher activity at the coast during specific parts of the tidal cycle. However, the exact patterns differed between tool-using and non-tool-using capuchins, as well as between the wet and dry season! Tool-using capuchins showed the strongest, most consistent coupling of coastal activity to the tidal cycles, in line with exploitation of tidal resources. Tool use may help capuchins process resources faster, and allows access to protected food.
These findings show how tool use can permit niche expansion, and provide insight into hominin behavior. Archaeological evidence of tool use in coastal areas is rarely preserved, so studying living non-human primates is one way to gain understanding of our evolutionary past.
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