Lukáš Poledník, Kateřina Poledníková, Václav Beran
The River Bílina is one of the most polluted rivers in the Czech Republic. Despite this fact, the Eurasian otter has re-colonised the river in the last decade. The presence of the otter was surveyed in the section of the river between the towns Komořany and Trmice. Apart from the presence survey, habitat quality of the environment was evaluated. Otter signs were found along all surveyed stretches (11 positive bridges = 50%), but the river is used rather as an important travelling route than a feeding place. The River Bílina provides good vegetation cover for day resting sites of otters along its course. Only three out of 76 evaluated points of road/railroad and river crossing are considered as potentially dangerous for otters and all of them present a low level of a collision risk. The high water pollution, resulting in low fish population, remains the major threat for otter population there. Several measures for improving the situation are suggested.