Habitat alteration impacts predation risk in an aposematic amphibian

Abstract

Predator–prey interactions can be viewed as an evolutionary arms race influenced by environmental factors. A common anti-predator strategy, known as aposematism, relies on the coupling of warning signals with secondary (e.g., chemical) defences to deter predators. The European fire salamander (Salamandra salamandra) is an emblematic, aposematic amphibian of the Biosphere Reserve Wienerwald (BRWW), a forest region where both protected areas and areas with forest management can be found. Differences between these areas are likely to affect the structure of predator communities and, in turn, their interactions with prey. Fire salamanders have a distinct yellow and black warning colouration and skin toxins that provide protection from predators, and the amount of yellow in their dorsum is negatively correlated with predation attempts. Here, we compare predation rates on clay models of fire salamanders with the same amount of dorsal yellow colouration distributed across either many small or few large markings, and placed in either protected or managed zones of the BRWW. We observed no differences in predation rates based on marking size, as all models were attacked with similar frequency. However, we found that bird attacks were more frequent in managed forest zones than in protected ones. The main differences between these forest zones were in tree diversity and evenness. We suggest that forest structure and complexity may lead to differences in either abundance or composition of predator communities which, in turn, might influence attack rates. Finally, we highlight the importance of protected zones as potential havens for fire salamanders and propose further research to test specifically the effect of differences in predator community composition on predation risk across forest zones.