The upward elevational shifts of pond breeding amphibians following climate warming

While poorly dispersing taxa such as amphibians may have limited scope to track recent and rapid climate change by means of large range shifts, they may follow their climate envelope with short elevational shifts in mountain areas. Such elevational shifts are poorly documented by empirical data for amphibians. In this study, we analysed a 15-year data series on the distribution of three amphibian species (Bufo bufo, Triturus carnifex and Rana temporaria) inhabiting a mountain pond network in the southern Italian Alps, where temperatures have increased significantly over the last decades. By using multi-season occupancy models, we estimated the occupancy trend of each species over the study period and tested the occurrence of an actual elevational shift after accounting for the probability of false absence. The upper elevational limit of the two eurythermal species (B. bufo and T. carnifex) underwent a significant and progressive upward shift of ca. 200 m. Our results provide evidence of the ability of amphibians to perform rapid elevational shifts, great enough to track predicted rates of climate warming. Preserving and improving habitat connectivity between lowlands and highlands could safeguard the opportunity for such elevational migrations, but mountain aquatic habitats must be preserved in order to provide a safe refuge for amphibians escaping climate warming.