Use of stable carbon isotope ratio for foraging behavior analysis of capybara (Hydrochoerus hydrochaeris) from Esteros del Iberá, Argentina

Abstract

We analyzed different aspects of the foraging behavior and habitat use for feeding of the capybara (Hydrochoerus hydrochaeris) using carbon stable isotopes (13C/12C) measured in bone collagen and by direct observation. Stable carbon isotope ratio analysis is used to determine the proportion of plant functional types consumed (C3 and C4 photosynthetic patterns). These data were further compared with the distribution of the plant functional types available in the different environments of the study area. There was a high variability in bone isotope values, and although some specimens showed a C4-based diet, data suggested a tendency toward a predominant consumption of C3 plants. The proportion of functional types in the diet of capybaras differed from their availability in the study area indicating a differential use of environments. We obtained similar conclusions by direct observation of capybaras. The high variability in isotope values and foraging behavior of the species may explain its high ecological plasticity in terms of both diet composition and selection of foraging sites.