Original InvestigationDiet of some species of Neotropical small mammalsNahrungsanalysen einiger kleiner neotropischer Säugetiere
Introduction
The eating habits and availability of food resources are essential aspects to understanding populations and communities of mammals, life-history strategies, and ecological roles of animals (DeBlase and Martin 1980; Meserve et al. 1988; Galindo-Leal and Krebs 1998; Martinez et al. 1990). Information about the eating habits of small herbivorous mammals, mainly rodents, is scarce due to their efficient food mastication, which results in small fragments, which are difficult to identify (Hansson 1970). In the Neotropics, some work has been done on food availability as correlated with habitat (Borchert and Hansen 1983; Martinez et al. 1990; Bergallo and Magnusson 1999), demographic population (Fleming 1971; González et al. 1989; Adler and Beatty 1997; Adler 1998; Bergallo and Magnusson 1999) and the reproductive cycle of those animals (Martino and Aguilera 1989; Bilenca et al. 1992; Suarez 1994). In Brazil, the details of the diet of small mammals is limited to some studies (Leite et al. 1996; Santori et al., 1996, Santori et al., 1997; Talamoni et al. 1999). One problem for diet analysis is that the diets of small mammals have often been studied by the analysis of faeces or stomach contents. Analysis of faeces is highly inaccurate because of differential digestion, and stomach contents analysis requires the sacrifice of large numbers of individuals and cannot be used for some species because of conservation considerations (Kronfeld and Dayan 1998). Thus, the animals of this study were also sacrificed for a reproduction study (Couto 2000). The objective of the present work was to determine the diet of some species—Oligoryzomys nigripes (Olfers, 1818), Oryzomys subflavus (Wagner, 1842), Necromys lasiurus (Lund, 1841), Oxymycterus delator (Thomas, 1903), from cerrado (a savannah-like grassland), and Philander frenatus (Olfers, 1818) and Akodon montensis Thomas (1913), from semideciduous forest, both seasonal vegetation types of Brazil, and to contribute to the knowledge of the trophic ecology of Neotropical small mammals.
Section snippets
Study site
The collection of small mammals was carried out monthly from October 1998 to October 1999, in seasonal semideciduous forest and cerrado areas, in the Serra do Rola-Moça State Park (PERM), in the state of Minas Gerais, Brazil (20°03′S, 43°57′W). The Park encompasses nearly 9500 ha, with elevations ranging from 1100 to 1400 m above sea level, and a mosaic of different plant communities include semideciduous forest, cerrado and open areas such as high-altitude fields. The cerrado is Brazil's second
Results
A great consumption of the vegetative parts of plants was observed, except for P. frenatus and O. delator, where analysis indicated a larger proportion of animal origin (55% and 61.6%, respectively). The consumption of small vertebrates was also observed in P. frenatus (Table 1). Indefinable fungi consumption was observed for A. montensis and O. delator. Animal and vegetal diets of A. montensis, the most captured species in the forest, and N. lasiurus, the most captured in the cerrado (Table 1
Discussion
Most rodents showed a herbivorous–omnivorous diet; however, O. delator was considered mainly insectivorous–omnivorous. The consumption of invertebrates in a greater proportion (70%), besides seeds and vegetal tissue, was previously observed in Oxymycterus roberti (Thomas, 1901) (Borchert and Hansen 1983) and Oxymycterus rutilans (Olfers, 1818) (Suarez 1994). In relation to P. frenatus, despite its omnivorous diet, it was observed to have a greater consumption of animal items, including the
Acknowledgements
We thank IBAMA for the licence to capture animals (098/99-NUFAS MG); the Sanitation Company of Minas Gerais (COPASA) for their permission to collect in the APE Mutuca; João A. de Oliveira, from the Museu Nacional do Rio de Janeiro, for the identification of Oxymycterus delator, and to A. Linghorn for English revision. FIP-PUC Minas provided financial support.
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