Sympatric rodents in a desert shrubland differ in arthropod consumption

The foraging ecology of sympatric mammals within xeric habitats is poorly understood. In this study, we surveyed the diets of two sympatric woodrat species, Neotoma bryanti, N. lepida and their hybrids in a desert shrubland during the dry season using stable isotope analyses of hair and arthropod DNA metabarcoding of feces. We found that woodrats regardless of their ancestry fed on similar plants during the same season across multiple years. However, stable isotope analyses and arthropod metabarcoding were consistent with greater arthropod ingestion by N. bryanti compared to N. lepida or hybrids. These results suggest that while the diets of these sympatric woodrats largely overlap during the dry season in terms of the plant components, they differ in terms of arthropod ingestion. This arthropod feeding may serve to reduce interspecific competition or act as dietary supplementation during nutritionally challenging periods. These results demonstrate that integrating DNA metabarcoding approaches with stable isotope tracers enables a more rigorous evaluation of animal foraging behavior. •Sympatric rodents feed on similar plants but differ in arthropod consumption.•Arthropod-feeding by an herbivorous rodent may promote nutrient acquisition during nutritionally challenging periods.•DNA metabarcoding and stable isotope analysis are complementary tools to study animal foraging behavior.