Preventing wildlife roadkill can offset mitigation investments in short-medium term

Abstract

Wildlife vehicle collisions (WVC) are a threat to wildlife and humans, killing millions of animals of numerous species, as well as causing significant damage to vehicles, drivers and passengers. Road fencing is a highly effective mitigation measure at reducing WVC, however its large-scale implementation requires a high investment. We questioned how long it would take for savings from avoided collisions to offset the investments in road fencing mitigation, focusing on vehicle damage costs. Using the information of a 3-year systematic roadkill monitoring of 1158 km in Mato Grosso do Sul, Brazil, we estimated the real number of casualties accounting for bias in roadkill counting. We obtained information on the material costs on cars and trucks due to WVC and, considering the road traffic volume characteristics, estimated the total material costs resulting from collisions with larger animals. Cost-benefit analyses allowed estimating the time required to amortize the investment in fencing, considering its application along the full surveyed roads or only in hotspots of mortality. We recorded over 10,000 WVC, 40% of which involved animals that can cause significant material damage to vehicles, namely the endangered lowland tapir (Tapirus terrestris, n = 267) and giant anteater (Myrmecophaga tridactyla, n = 608). The average material cost per accident was US$ 885 ± 1575 (mean ± SD). We show that investments are likely to pay off in 16–40 years for the mitigation of the full roads, and in 9–25 years for hotspots of mortality. Thus, road mitigation is a win-win solution for increasing traffic safety for humans and reduces road-related negative effects on biodiversity.