Urban roadkill assessment in Vienna reveals low incidence rates

Abstract. An important factor in the decline of global animal diversity is road traffic, where many animals are killed. This study aimed to collect data on vertebrate roadkill in the city of Vienna, Austria, between 2017 and 2022 using three different approaches: citizen science, systematic monitoring by bicycle along a 15 km route, and systematic monitoring on foot along a 3 km route. During 359 monitoring events, only four roadkill incidences (three Erinaceus sp., one Rattus sp.) were found by bicycle or on foot. At the same time citizen scientists reported 1 roadkill squirrel on the bicycle route and 84 roadkill incidences for the entire city area. Hedgehogs and urban birds were commonly reported species by citizen scientists. Although no amphibian or reptile roadkill was found during systematic monitoring, they were reported by citizen scientists. The low number of roadkill incidences found suggests a potentially low population density that makes the impact of roadkill even more severe – a hypothesis that should be further investigated amidst the global decline in biodiversity.