The effects of landscape structure and road topography on mortality of mammals: A case study of two different road types in Central Slovakia [Vplyv štruktúry krajiny a topografie cesty na mortalitu cicavcov: prípadová štúdia z dvoch typov ciest na stredno
Peter Bitušík, Marcela Kocianová-Adamcová, Juraj Brabec, Radovan Malina, Jerguš Tesák, Peter Urban
The magnitude, composition, temporal and spatial patterns of mammal road mortality were assessed along some sections of two different road types (I/51 and R1) connecting the towns of Banská Bystrica, Zvolen and Banská Štiavnica (Central Slovakia). Road kills were surveyed using a car, three or four times per week from March 2008 to December 2012. We conducted 440 surveys, traveling a total of 39,700 km, and recorded 5,416 road mortality events (120 kills per km on average). Mammals were represented by 693 individuals (12.8% of the total number of carcasses) identified into 20 species and categories, respectively. The most frequently identified species were fox, hedgehog and domestic cat, a substantial part fell into the category of small mammals, as they could not be mostly identified to a genus. We found significant temporal and spatial differences in the magnitude of road-kills and identified several road segments as mortality hotspots both for all observations and for each season. Using logistic models we found significant relationships between the number and composition of the mammal casualties and higher proportion of arable land, built-up areas and roads in the landscape bordering the roads. Road topography was found to be among the important variables in explaining road-kills as carnivores were most susceptible to be killed on the raised segments and insectivores and herbivore mammals on the raised or buried segments of the roads. Construction of the fence along the R1 expressway in 2010 was related to significant decrease in road-kills, however, significantly higher mortality level was recorded at the segments with the underpass where streams with line riparian vegetation are crossed by the road. This effect was not identified at segments with expressway feeders. This finding suggests that the line vegetation continues to serve as migration corridor and leads animals to the R1 road where they find defects in fencing and try to cross through them and enter the road.