A possible mutualistic dispersal system between a large-seeded tree of French Guiana, Vouacapoua americana (Caesalpiniaceae), and caviomorph rodents, Myoprocta exilis and Dasyprocta leporina, is described. Mast fruiting of Vouacapoua at the beginning of the wet season coincides with scatter-hoarding seed dispersal. During the wet season, almost 100% of marked seeds on three sites were removed: nearly 70% were buried and the rest were eaten by mammals. Unburied seeds were attacked by insects and/or lost their ability to germinate. Rodents preferred ungerminated seeds, and had no interest in germinated seeds. Seeds were buried individually near natural objects such as palms, branches, logs, lianas, roots and trees. After predation by rodents, seedling distribution did not differ from seed distribution. Most seeds were transported less than 5 m from the feeding plots but some were carried as far as 22.4 m. Between 40 and 85% of dispersed seeds were retrieved during the following month by rodents and eaten. The disinterest of caviomorph rodents in germinated seeds, because of rapid exhaustion of endosperm reserves, prevents feeding from hoarded Vouacapoua during the long dry season when resources are scarce. Seedlings emerging from forgotten or abandoned cached seeds appear to increase the recruitment of Vouacapoua americana.

The diets of the acouchy Myoprocta exilis, agouti Dasyprocta leporina and paca Agouti paca, the three largest terrestrial rodents of French Guiana forests, were investigated from stomachs collected over several years. These species are primarily frugivores. The percentage of fruit in their diet decreased, and seasonal variation increased from the smallest species, the acouchy, to the largest, the paca (contents in dry mass: respectively, 98.5% ± 0.6%, 87.4% ± 3.5%, and 83.9% ± 7.6%). They differed from each other in the proportions of pulp and secondary foods (leaves, fibre, insects) consumed annually as well as seasonally. Dietary diversity in the acouchy was half that of the two other species. The seasonal variation in consumption of different fruit parts and of secondary foods by these species corresponded well with the fruit production in the forest, and was linked to their reproductive events. Overall, the diets of these three large rodents appeared intermediate between the small rodent species and the artiodactyls (peccaries and brocket deer) inhabiting the same areas, which also concords with their body mass and their place within the guild of terrestrial mammals.