Native red foxes depredate nests of alien pond sliders: Evidence from molecular detection of prey in scats

Predation by native species is a chief resistance factor that may counter the spread of alien organisms. Its comprehension plays therefore an important role to assess the impact of biological invasions and implement management. In this study, we show for the first time that red foxes (Vulpes vulpes) may depredate nests of alien pond sliders (Trachemys scripta). We set our work in a Mediterranean area of Southern Italy where both species are frequent. We observed that red foxes excavated pond slider nests to eat the eggs. We then used a molecular approach to demonstrate the presence of pond slider's DNA in the carnivore's scats, and found that pond slider's DNA occurred in over half of the scat sample collected during the oviposition season. Whether egg consumption by red foxes is widespread rather than only a local response and might eventually lead to population control of pond sliders needs further investigation