Amphibians in an urban environment: a case study from a central European city (Wrocław, Poland)

In 2016, we studied the occurrence of amphibians in 231 selected ponds in the city of Wroclaw (Lower Silesia, Poland) and confirmed the occurrence of 10 species: Bombina bombina, Bufo bufo, Bufotes viridis, Hyla arborea, Pelobates fuscus, Pelophylax esculentus complex, Rana arvalis, Rana temporaria, Lissotriton vulgaris and Triturus cristatus. Among all studied sites, the most common were P. esculentus complex (146 occupied sites, 63.2%) and B. bufo (119, 51.5%), while the rarest was P. fuscus (8, 3.5%). The number of species at a single site varied from 0 (28 sites, 12.1%) to 9 (1 site, 0.4%). Frequency and mean amphibian species richness reached 87.9% and 2.7 ± 1.9, respectively. The composition of amphibian species did not change in comparison to previous studies conducted in the years 1997–2009, but declining trends in five species (B. bombina, B. viridis, H. arborea, P. esculentus complex, P. fuscus) were observed (28 compared sites). The results revealed that the permanency of ponds, their occurrence in the vicinity of river valleys, and a high ratio of watercourse length and green area around ponds are positively correlated and have a significant influence on amphibian species richness within the city. Thus, these identified factors should be considered in the course of sustainable urban planning in order to avoid potential conflicts between nature conservation and urban development.