Wildlife mortality risk posed by high and low traffic roads

Abstract

Wildlife mortality due to collisions with vehicles is considered one of the predominant negative effects exerted by roads on many species. Reducing roadkill is therefore a major component of wildlife conservation. Roadkill is affected by various factors, including road attributes and traffic volume. It was theorized that the effect of traffic volume on roadkill probability should be unimodal. However, empirical evidence of this theory is lacking. Using a large‐scale roadkill database of eighteen wildlife species in Israel, encompassing 2,846 km of roads over a period of 10 years, we explored the effects of traffic volume and road attributes (e.g., road lighting, verge vegetation) on roadkill probability using a multivariate GLMM analysis. A unimodal effect of traffic volume was identified for the striped hyena (Hyaena hyaena), while five species demonstrated a novel quadratic U‐shaped effect (e.g., golden jackal (Canis aureus)) and four species showed a negative linear effect (e.g., wild boar (Sus scrofa)). We also identified varying effects of road attributes on roadkill. For instance, road lighting and roadside trees decreased roadkill for several species, while bus stops and concrete guardrails led to increased roadkill. The theorized unimodal effect of traffic volume may only apply to large, agile species, while the U‐shaped effect could be related to intraspecies variability in traffic avoidance behavior. Altogether, our study revealed that both high traffic and low traffic roads can pose a high mortality risk for wildlife. It is therefore important to monitor roadkill on low traffic roads and adapt road attributes where possible, to improve road design for wildlife. An effective roadkill reduction strategy can benefit from combining road design measures like reducing the use of concrete guardrails and median barriers, with mitigation measures that are suitable for low traffic roads, such as wildlife detection systems combined with driver warnings, and seasonal traffic calming.This article is protected by copyright. All rights reserved

Trends and Characteristics of Human Casualties in Wildlife–Vehicle Accidents in Lithuania, 2002–2022

“…Wildlife-vehicle accidents occur at the intersection of roads and wildlife, resulting not only in human casualties and property loss but also in wildlife mortality and changes in their behavior [26]. Mitigation measures, especially wildlife fencing and passages, must prioritize the safety of multiple species [82] and address the risk to motorists' safety [14].…”

“…In the earlier decades, WVA investigations focused on the main roads [21][22][23], and recently, problems have arisen even in the urban areas [24,25] and require attention. As WVAs occur also on the low traffic intensity roads [26,27], wildlife fencing is not a universal solution [28].…”

Mammal Roadkills in Lithuanian Urban Areas: A 15-Year Study

“…In suburbs and other urban-wildlife interface areas, the migration of animals, especially ungulates, increases the risk of these collisions [21]. The intensity of wildlife-vehicle collisions (WVC) is influenced by differences in land cover, traffic volumes, and mitigation measures; however, the relationship between WVC and traffic intensity is not the same for different mammalian species, being unimodal (negative linear, positive linear) or U-shaped [22].…”