As roadways reduce amphibian population sizes, disrupt connectivity, and degrade habitat mitigation measures are increasingly being implemented. Barriers-ecopassage systems are a common strategy used to mitigate roadway impacts. Barriers limit access to roadways and may direct animals toward ecopassages, which are corridors designed to conduct animals safely over or under the roadway. The effectiveness of these mitigation measures for small animals, such as amphibians, remains poorly studied. We quantified levels of roadway mortality, ecopassage use, and amphibian populations, to assess the effectiveness of a barrier-ecopassage system along a two-lane highway in southeastern Ohio. We also conducted roadway crossing behavioral observations of eight amphibian species. Throughout 2015 and 2016, we detected 25 amphibians in the ecopassages, with eight of those individuals completing passage, during the same period 13,251 amphibian carcasses were detected along the road. We found that road crossing success rate varied by amphibian species from 69.8% (Pickerel Frog, Rana palustris) to 11.2% (Red-spotted Newt, Notophthalmus viridescens). Our findings indicate that this barrier-ecopassage system is minimally effective and that amphibian road crossing success is low for some species. In our discussion we will present potential improvements for future mitigation structures and the implications of low crossing success rates on population persistence.
Planning for Transportation Ecology