Rare nonhuman primate tool-use culture is threatened by land use changes in northeastern Brazil

Abstract

Animal traditions are increasingly threatened by human impact on natural habitats, posing a challenge to conservation policies. In northeastern Brazil, bearded capuchins (Sapajus libidinosus) inhabiting the Cerrado–Caatinga biome of Fazenda Boa Vista use stone hammers and anvils to crack open palm nuts and other encased foods. The same species inhabiting the mangroves of Morro do Boi ambush crabs and process them using wooden hammers and anvils. These traditions are gradually acquired by young capuchins exposed to the tool using activity of skilled older group members. Changes in land cover have threatened the persistence of this species, where these rare tool-use traditions occur. To assess land cover changes over the past 30 years, we analyzed a time series of remotely sensed imagery and quantified trends in land cover and agriculture across both study sites. We also developed a predictive model to forecast future changes in land cover by 2034. Our results show that agriculture increased by more than 300% in both sites from 1987 to 2017. If current trends continue in Morro do Boi, only 42% of forest (0.15 km2) will remain, which is insufficient to support the resident population of capuchins. In Fazenda Boa Vista, most of the land suitable for agriculture has already been used for that purpose. If private conservation efforts at Fazenda Boa Vista are to be effective through 2034, agricultural use should not be expanded any further. Imminent erosion and loss of natural vegetation will exacerbate the current situation, even if agriculture is not expanded. Our study is an example of the need for conservation to take behavioral traditions into account, as they are not widespread across the species distribution.