Diet of the Invasive Greenhouse Frog, Eleutherodactylus planirostris, in Taiwan

We conducted stomach content analyses to elucidate the diet of the nonnative greenhouse frog, Eleutherodactylus planirostris, across 10 invaded sites in Taiwan. Dietary importance was quantified using the index of relative importance (%IRI), and diet breadth was assessed using the Shannon index (H'). We found that frog diets included three invertebrate phyla (Annelida, Arthropoda, Mollusca), seven classes (Clitellata, Arachnida, Chilopoda, Diplopoda, Malacostraca, Insecta, Gastropoda), and at least 17 orders. Formicidae (ants) were consistently the most important prey across life stages (%IRI adult=64.72; juvenile=49.07), seasons (%IRI breeding season=66.07; non-breeding season=93.22), and regions (%IRI=42.70–91.53), indicating strong myrmecophagy. Adults had a broader diet (H'=1.91) than juveniles (H' =1.67), reflecting an ontogenetic dietary shift from small-bodied prey, such as ants and mites, to larger prey including beetles, orthopterans, and cockroaches. Diet breadth was broader during the breeding season (H'=1.89) than during the non-breeding season (H'=1.29), with increased ant specialization and more empty stomachs in the non-breeding season. Although ants were the dominant diets at all sites, secondary prey taxa varied regionally, suggesting dietary flexibility in response to local prey availability. Overall, Eleutherodactylus planirostris in Taiwan combine strong ant specialization with opportunistic foraging, a strategy that likely facilitates invasion success and may intensify predation pressure on litter invertebrates as well as competition with native insectivorous amphibians in lowland ecosystems.