Does the shape of the road influences wildlife roadkills? Evidence from a highway in Central Andes of Colombia

Abstract

Highway infrastructure is a source of multiple environmental problems, where wildlife roadkills is the most noticeable impact. Most of research in roadkills have focused in how different aspects as seasons, traffic density, location of roads, among others, have implications in the wildlife mortality on roads. However, little research have been developed on understanding how geometrical road design affects wildlife mortality. On a highway in the central Andes of Colombia, we tested whether the geometric design, it is horizontal alignment and vertical curves influence the mortality of vertebrate animals on the road. We determined the number of straight lines, circular, transition curves and vertical convex curves along the entire route of the highway (13.9 km), and between April 2018 and December 2019 we made 4 weekly tours in search of wildlife roadkills. With records, we related and compared groups of animal deaths and road shapes. We got 95 roadkills where reptile’s deaths were more than the 47% of total. We found no dependence in the distribution of deaths by Class of animals on the road shapes; the shape in which most deaths occurred was straight line (58 deaths). However, when the mortality rate per meter of route was obtained on the shape units, we found that the circular and transition curves presented two and three times (respectively) higher mortality rates than straight lines. Curved sections are presented as more dangerous geometric designs than straight lines for wildlife, regardless of their length on the road. Our research provides information necessary to take into account the relationship of geometric road design in the development of management and conservation plans of altered ecosystems with road infrastructure.