Diet composition and niche overlap of sympatric anurans in cropland and forest of lowland, Nepal

Dietary variation in sympatric anurans is important for understanding ecological niche of a species which have allowed it to live in various habitats and ecosystems. Croplands are crucial for amphibians that help to control crop pest and also play vital role in forest ecosystem. Hence, this study aimed to examine dietary habits and niche overlap of anurans in cropland and forest of western side of Barandabhar Corridor Forest, Central Nepal. Nocturnal time-constrained visual encounter transect survey using 100 m long transect with at least 250 m apart was used for the anuran survey during monsoon. Non-lethal stomach flushing technique was applied for the extraction of diet and examined microscopically. Twenty-nine (22.83%) individuals out of 127 stomachs flushed were found with empty stomach. The diet contained 442 prey items including 16 taxonomic groups. Hymenoptera (62.89%) was highly abundant prey, followed by Coleoptera (10.40%). Prey-Specific Index of Relative Importance (%PSIRI) analysis showed that Hymenoptera as the most important prey category which was consumed by all of the captured anurans (%PSIRI= 43.29%). The relation between weight of prey uptake was significantly correlated with the Snout-Vent Length (SVL) (R2=0.399, p<0.0001). Similarly, dietary preferences were not significant with habitat types (t =0.08, p=0.931). The result of Non-metric Multidimensional Scaling showed high degree of dietary niche overlap between the anurans species in both cropland and forest habitat. Common Asian Toad had the highest niche breadth (BA = 0.42) and high dietary niche overlap (0.985) followed by Minervarya teraiensis (average SVL= 46.13) and Duttaphrynus melanostictus (average SVL= 63.68 mm). This study evaluated the dietary composition, effect of body size on prey consumption and dietary niche overlap of anurans in croplands and forests of Central Nepal emphasizing their ecological role in pest control and forest ecosystems. This indicates adaptability and potential competition among sympatric anurans in varying habitats. Hence, this study will be baseline for the conservation of amphibians.