Trophic Relationships of Small Mammals in a Chilean Temperate Rainforest

Abstract

Food habits were determined from analysis of stomach contents of nine species of small mammals that inhabit primary-growth temperate rainforest in southern Chile. Species included rodents ( Akodon olivaceus, A. longipilis, A. sanborni , putative A. longipilis × sanborni hybrids, Oryzomys longicaudatus, Geoxus valdivianus, Irenomys tarsalis , and Auliscomys mi-cropus ) and marsupials ( Rhyncholestes raphanurus and Dromiciops australis ). Diets throughout the year were determined for the first three species, but primarily during summer (December-March) for the remaining species. Species of Akodon generally were omnivorous, with the stomach contents of A. olivaceus containing smaller proportions of vegetation and fungi than those of other species in most periods. A. olivaceus also had seasonally greater, but approximately equal overall proportions of arthropods, seeds, and fruits in the diet. O. longicaudatus, I. tarsalis , and A. micropus were broadly granivorous-frugivorous with plant material, but not fungi, comprising significant proportions of the diet. Invertebrates, primarily arthropods and annelids, dominated diets of G. valdivianus and R. raphanurus , but significant amounts of nonepidermal plant material and fungi also were present. D. australis fed on arthropods, but also ate some seeds and vegetation. Overall, diets of these small mammals were relatively omnivorous; because this contrasts with patterns of trophic specialization for many of the same species elsewhere, resource availability rather than evolutionary specialization may contribute more in determining patterns of use of local food resources.