The partitioning of food resources between two rodents in the subtropical region of southern Brazil

Abstract

The capybara (Hydrochoerus hydrochaeris) and nutria (Myocastor coypus) are herbivorous semi-aquatic rodents. Although these rodents occur in sympatry in southern South America, little is known about how the two species interact in relationship to food resources. In this context, the aim of this study was to analyze the food resource overlap, the feeding strategy and the diversity of the diet of capybaras and nutria. A micro-histological analysis of feces was used to study the diets. A total of 48 plant species belonging to 10 families were identified in the diet of H. hydrochaeris, and a total of 49 species belonging to 14 families were identified in the diet of M. coypus. According to the Amundsen graphical method, both rodents adopted a specialized strategy for feeding on Poaceae and a generalized strategy for other families. The results of a multivariate analysis of the dietary data showed significant differences between the two rodent species and among the seasons. These differences between diets may be related to the different proportions of each food item eaten. However, the dietary overlap between the two rodents in the Taim wetland was high, suggesting that partitioning of other resources ensured the coexistence of the species.

Big rodents disperse small seeds and spores in Neotropical wetlands

“…Given their herbivorous diets (Borges & Colares, 2007;Colares et al, 2010;Mones & Ojasti, 1986), we hypothesized that these two Neotropical mammals are dispersal vectors for a variety of wetland plants. We also tested the hypothesis that they disperse different sets of plants, since capybaras are larger, can reach a greater height for grazing, and have more terrestrial habits than nutrias (Espinelli et al, 2016). Wetlands in southern Brazil contain both herbaceous vegetation with small seeds, and woody vegetation with larger seeds (Rolon et al, 2010;Silva et al, 2021;Wiesbauer et al, 2008), and we also tested the hypothesis that the larger rodent would disperse larger seeds and more species of seeds (Chen & Moles, 2015).…”

“…(Maltchik et al, 2003). Approximately 142 herbaceous plants present in wetlands of the region are available as food to the two mammals studied (Espinelli et al, 2016). These wetlands feature extensive emergent macrophyte beds, dominated by Zizaniopsis bonariensis (Balansa & Poitr.)…”

Food Preference of Cavia magna (Rodentia: Caviidae) on a Subtropical Island in Southern Brazil

“…The use of the latter technique relies on the fact that plants have non-digestible structures, so it is possible to identify them in the feces [6]. This kind of analysis has been used to define the feeding habit of many herbivores [7,8,9,10].…”