Prey Selection And Trophic Position Of Southern River Otter (Lontra provocax) In The Wetlands of the “Carlos Adwandter Nature Sanctuary”, Southern Chile

Otters are considered as top predators and participate in ecosystem services and affect community structure by the modulation of prey densities. Nevertheless, diet of the southern river otter (Lontra provocax) has been described only based on the frequency of occurrence of prey in feces. Actually, the relationship between trophic availability and prey selection is unknown. In this study we evaluated the relationship between prey selection and availability in different environments. We hypothesized that this species is an opportunistic predator, and that their diet could be determined by prey abundance. We studied fecal remains in two different environments (marsh–river) in the “Carlos Andwanter Nature Sanctuary” in southern Chile. The prey found in the scats were identified through reference collections. We estimated the frequency of occurrence, relative availability of prey item, and the Selection Index. In addition, we quantified prey availability using electrofishing. Our results suggest that the trophic niche for L. provocax is restricted to a few prey items, with crayfish (Samastacus spinifrons) as the most important diet component. However, L. provocax consume specific crayfish size independently of their availability in the environment. Our results suggest that L. provocax is an opportunistic predator, but shows a clear selection of medium-sized crayfish.