Trophic ecology and microhabitat utilization by the Bufo gargarizans, Rana guentheri, and Rana limnocharis in southwestern China

Tonglei Yu,Yanshu Guo

doi:10.1590/s1984-46702012000100006

Abstract

We studied the trophic ecology and microhabitat use of the Asiatic toad, Bufo gargarizans Cantor, 1842; Guentheri frog, Rana guentheri (Boulenger, 1882); and the Ricefield frog, Rana limnocharis (Boie, 1834). These three species are common around Nanchong City, in southwestern China, where they live in the same habitat before hibernation. The main objective of this study was to analyze the diets and patterns of coexistence relative to the microhabitat of each species. In the Asiatic toad, based on index of relative importance, the diet was dominated by adult Coleoptera, Isopoda, and Hymenoptera (29.53%, 22.07%, and 15.20%, respectively), while the Guenther's frog and Ricefield frog ingested predominantly Orthoptera (67.44% and 40.94%, respectively). The standardized feeding niche breadth of the Asiatic toad (0.277) was wider than that of the Guentheri frog (0.177) and Ricefield frog (0.269). The overlap in the trophic niche (prey proportion) between the toad and two species of frog was low (toad vs. Guentheri frog, C H = 0.526; toad vs. Ricefield frog, C H = 0.521), while this was high for the two species of frogs (C H = 0.942). The three species also differed in microhabitat use. Asiatic toads showed strong preference for small roads close to shrubs or pre-harvest corn, while Guenther's frogs preferred bare surfaces on habitat edges, and Ricefield frogs showed a preference for bare surfaces as feeding sites in the middle of habitat. The difference in diet observed during three species seems to be explained by the difference in microhabitat use and body size of three species.

Highlights

The variation in resources used by sympatric amphibian species may not necessarily reflect competition
We studied feeding habits and microhabitat use of three species of anuran, addressing the following aims: 1) to describe three anuran species, 2) identify and quantify the prey consumed by three species, 3) to calculate the niche width, niche overlap and diversity of the diet of B. gargarizans, R. guentheri and R. limnocharis, and 4) to establish the relationship between diet and microhabitat used by the three species
Plant remains such as leaves, hydrophyte, small twigs and seeds, as well as dirt were observed in 15 (13.76%) stomachs

Summary

Introduction

The variation in resources used by sympatric amphibian species may not necessarily reflect competition. Empirical research showing differences between sympatric species in the use of trophic, temporal and spatial niches have frequently been used to describe and explain community structure (PIANKA 1975). The segregation of these niche dimensions may permit the partitioning of resources, and the ecological coexistence of species. Supposedly exposed to a similar spectrum of prey, they have some differences, which may result in differences in the type and range of prey that they ingest They belong to two distinct families, and our preliminary field observations suggested that they differ in body size and probably in microhabitat use. We studied feeding habits and microhabitat use of three species of anuran, addressing the following aims: 1) to describe three anuran species, 2) identify and quantify the prey consumed by three species, 3) to calculate the niche width, niche overlap and diversity of the diet of B. gargarizans, R. guentheri and R. limnocharis, and 4) to establish the relationship between diet and microhabitat used by the three species

Objectives

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Results

Conclusion