Feeding of small rodents on seeds and fruits: a comparative analysis of three species of rodents of the Araucaria forest, southern Brazil

摘要

We investigated the feeding of three small-sized sigmodontine rodents (Oligoryzomys nigripes Olfers, 1818, Akodon montensis Thomas, 1913, and Delomys dorsalis Hensel, 1872) on fruiting plants in the Araucaria forest of southern Brazil. We offered to wild-captured animals fruits of 22 plant species in 14 families. For each individual, we recorded consumption patterns of pulp and seed. We also analyzed fecal samples to determine the relative abundance of invertebrates, fruit and seed parts, and fungi. The three rodents showed marked potential frugivory, feeding on most species offered. Only O. nigripes showed differences in relation to seed-size categories, consuming a high proportion of 'small' (diameter <= 2.5 mm) vs 'large' seeds. The rodents may be involved in seed dispersion of three plant species, by defecation of viable seeds of two Leandra (Melastomataceae) species and also by removing the pulp of Myrceugenia miersiana (Myrtaceae) fruits without swallowing or damaging their relatively large seeds, thus, potentially increasing germination rates of M. miersiana. Diet analyses indicated no significant difference among proportions of seed/fruit in the fecal samples of the three species of rodents (33 to 41% of plant material). Our results suggest that the three focal species are the main small-mammal seed predators on the ground of Araucaria forests.