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Additional Information

Competing Interests

The authors declare they have no competing interests.

Author Contributions

Michelle A Rodrigues conceived and designed the experiments, performed the experiments, analyzed the data, wrote the paper, reviewed drafts of the paper.

Emily R Boeving wrote the paper, reviewed drafts of the paper.

Animal Ethics

The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):

This research involved non-invasive observation from public viewing areas of three zoological institutions. Each institution (Brookfield Zoo, Columbus Zoo, and North Carolina Zoo) as well as the Chimpanzee Species Survival Program each reviewed and approved the research.

Data Deposition

The following information was supplied regarding data availability:

Raw data will not be released as additional analysis is underway for future publication


The authors received no funding for this work

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