The aim of the study was to monitor the efficiency of compensation measures for Pelobates fuscus at a new 26 km 4-laned highway opening for traffic in 2012. 141 new breeding ponds were created and 69 existing ponds restored to compensate for the negative effects of the road. 37 of the new ponds and 9 of the restored were supposed to compensate for negative effects on Pelobates fuscus. These ponds were situated in 4 areas with populations of Pelobates fuscus. 8 amphibian tunnels with amphibian fence were constructed to connect Pelobates fuscus habitats. The distribution and population size of Pelobates fuscus was monitored in 2014. The use of the tunnels was monitored in 2012. Distribution and population size of Pelobates fuscus and other amphibians was studied before the construction work in 2001-2 and 2007. The method used in 2001-2 and 2007 was counting male calls in spring and looking for juveniles during summer. In 2014 an underwater hydrophone was used to register male Pelobates fuscus in April. The use of tunnels was studied by an expert walking through the tunnel and the openings in August-September 2012 in warm and humid weather (6 times each tunnel). At Søgårdsmark the Pelobates fuscus population in 2014 was around 201 males in 21 ponds. In 2007 only 55 males were found in 7 ponds. It seems as if the species has had a high breeding success in several ponds and that a large number of ponds had been colonized. In 2001-2 and 2007 only 3 and 1 pond north of the highway respectively was a Pelobates fuscus habitat. After construction of the highway Pelobates fuscus was found in 9 ponds north of the highway and 12 ponds south of the highway. The population size of Pelobates fuscus north and south of the highway respectively at Søgårdsmark was higher in 2014 after construction than the total population size in the overall area before the highway was constructed. 5 amphibian tunnels connect the habitats north and south of the highway. Pelobates fuscus was not found inside any of the tunnels but in the very proximity of one tunnel opening to the south. The tunnel opening was situated very close to a Pelobates fuscus breeding pond south of the highway. Other amphibians, badger and hare used the tunnels. At Potterhus the population size in 2014 was 24 males in 3 ponds all situated north of the highway where Pelobates fuscus was also present in 2001-2 and 2007. No new ponds were colonized. The population size seems to be at the same level as before the highway. 3 amphibian tunnels connect the habitats north and south of the highway. 2 of these were not constructed correctly and are not functional fauna tunnels. The third tunnel was well constructed. Pelobates fuscus was not found inside the tunnel but in the very proximity of the tunnel opening to the south. This is interesting as we did not find any breeding Pelobates fuscus in the ponds south of the highway.
mitigation measures, compensation, efficiency, amphibians, monitoring, fauna passages