Anuran Richness and Abundance along an Elevational Gradient in Chebera Churchura National Park, Southwestern Ethiopia

Abstract

Elevational gradients are fundamental drivers of biodiversity, yet their influence on anuran communities in many of Ethiopia’s protected areas remains poorly understood. This study investigated the altitudinal distribution, species richness, and abundance of anurans in Chebera Churchura National Park (CCNP), southwestern Ethiopia. Using a combination of standardised visual encounter surveys (VES) and pitfall traps, we sampled along an elevational gradient from 865 m to 2400 m, which corresponds to three major transitions in temperature, vegetation structure, and moisture regimes. Surveys were conducted during both wet and dry seasons. We recorded 2,175 individuals representing 16 species from eight families. Species richness and abundance followed unimodal (hump-shaped) distributions, peaking at mid-elevations (~1,200 m). Quadratic regression confirmed that intermediate altitudes provide an ecological optimum for anuran communities, while diversity declines towards lower and higher elevations. These results highlight the importance of mid-altitude habitats as local centres of high anuran diversity within CCNP. However, the occurrence of elevation-restricted species and the observed variation in diversity along the altitudinal gradient indicate that different elevational zones support distinct anuran communities. This underscores the importance of conserving habitats across the full altitudinal range of CCNP, particularly mid-elevation areas with high diversity as well as habitats supporting range-restricted species. Protection of indigenous forests and permanent aquatic habitats, including rivers, streams, and wetlands, is therefore critical for sustaining anuran diversity within the park.