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Abstract

Capuchins can employ several strategies to deal with
environmental challenges, such as using stone tools to access
encapsulated resources. Nut-cracking is customary in several
capuchin populations and can be affected by ecological and
cultural factors; however, data on success and efficiency
are only known for two wild populations. In this work,
using camera traps, we assessed palm nut-cracking success
and efficiency in two newly studied wild bearded capuchin
populations (Sapajus libidinosus) and compared them with
other sites. We tested the hypothesis that the overall success
and efficiency of nut-cracking would be similar between sites
when processing similar resources, finding partial support for
it. Although using hammerstones of different sizes, capuchins
had a similar success frequency. However, efficiency (number
of strikes to crack a nut) was different, with one population
being more efficient. We also tested whether success and
efficiency varied between sexes in adults. We predict adult
males would be more successful and efficient when cracking
hard nuts. We found no differences between the sexes in one
site but found sex differences in the other, although also for
the low-resistant nut, which was unexpected. Our data add to
the knowledge of capuchin nut-cracking behaviour flexibility,
variance and potential cultural traits.