The problem of forest fragmentation causes, among other things, the loss of biodiversity; here in Brazil is no different. Therefore, we decided to evaluate if the size of the fragment also affects the availability of resources for the non-human primates in the Atlantic Forest and if the presence of medium and large frugivorous primates can influence the diversity and forest structure. For this, we studied three forest fragments and used different Shannon, Alpha-Fisher and Simpson diversity indexes, as well as analyzing alpha and beta diversity. After all, can the presence of medium and large-sized primates, such as the guaribas (Alouatta belzebul), affect the diversity and availability of resources?