Rare and Hungry: Feeding Ecology of the Golden Alpine Salamander, an Endangered Amphibian in the Alps

SIMPLE SUMMARY: We investigated the trophic ecology of the Golden Alpine salamander (Salamandra atra aurorae), a rare and endemic amphibian found in a mixed temperate forest in northern Italy. We aimed to determine the salamander’s trophic niche, prey selectivity, and individual specialization in foraging. We analysed stomach contents from 53 salamanders obtained by stomach flushing technique and assessed prey availability through pitfall traps. The results revealed that the Golden Alpine salamander adopts a generalist feeding strategy at the population level but selectively prefers certain prey categories, such as Myriapoda and Hymenoptera (except Formicidae). Factors like prey size, movement ability, and degree of chitinization seem to influence food preference. The study also found significant inter-individual variation in dietary preferences, which was discussed in relation to optimal diet theory. Our research provides valuable insights into the diet of the Alpine salamander complex, suggesting similar feeding strategies between the subspecies. ABSTRACT: Amphibians are considered critical species in the nutrient flow within and across ecosystems, and knowledge on their trophic ecology and niches is crucial for their conservation. For the first time we studied the trophic ecology of the rare and endemic Salamandra atra aurorae in a mixed temperate forest in northern Italy. We aimed to define the realized trophic niche, investigate the prey selectivity and explore possible levels of individual specialization. In summer 2022 we obtained stomach contents from 53 salamanders by stomach flushing and prey availability using pitfall traps. We used the Costello graphical method to analyse the realized trophic niche, and the relativized electivity index to study prey selectivity. Our results show that the Golden Alpine salamander adopts a generalist feeding strategy with positive selection of few prey categories (e.g., Myriapoda, Hymenoptera except Formicidae). Food preference seems to be driven by size, movement ability and chitinization of the prey. A high degree of inter-individual diet variation, modularity and clustering was found, describing a scenario that can be framed in a Distinct Preference model framework. This study gives new insights on the trophic ecology of the Alpine salamander complex, whose subspecies appear to adopt similar feeding strategies.