Diet and isotopic niche variation of mammals associated with road zones in Uruguay

Abstract

The understanding of the resource use and partitioning of medium and large terrestrial mammals in anthropogenic environments such as road areas is crucial for comprehending ecosystem dynamics and reveals how species coexist and adapt to environmental changes. The aim of this work was to characterize trophic aspects of medium and large terrestrial mammals, including the quantification of resource use, variation in isotopic trophic niche breadth and overlap among sympatric species within a road zone influence in Uruguay. To this end, stable isotope ratios (δ13C and δ15N) were examined in hair samples collected from 57 individuals from road-killed animals including 9 medium and large mammals species, as well as potential resources. The isotopic results reflected a community that contains four trophic levels, with Galictis cuja as a predator while the species Dasypus hybridus and Subulo gouazoubira were in the primary consumer levels. Furthermore, the results showed varying degrees of isotopic trophic niche breadth, suggesting different feeding strategies and degrees of dietary specialization. Additionally, a high degree of overlap in resource use was observed among these sympatric species with the exception of Galictis cuja, suggesting that spatial and temporal differentiation in resource use could help to explain the coexistence patterns. Diet composition estimated using Bayesian stable isotope mixing models revealed that in most species, the basal food source was represented by a combination of natural grasslands of types C3 and C4. This trophic behaviour with the incorporation of diverse and variable food items helps to explain the occurrence of these species within this complex environment.