Differences in Spatiotemporal Patterns of Vehicle Collisions with Wildlife and Livestock

Road ecology research has tended to focus on wildlife-vehicle collisions (WVCs) while omitting or failing to differentiate domestic (i.e., livestock) animal-vehicle collisions (DAVCs). This has limited our understanding of where, when, and how frequently DAVCs occur, and whether these patterns differ from those for WVCs. We used a 10-year collision data set for the U.S. state of Montana to compare temporal and spatial patterns of DAVCs versus WVCs at multiple scales. WVCs exhibited two diel peaks (dawn and dusk) versus only one prominent peak (late evening/early night) for DAVCs. Seasonal patterns of WVCs and DAVCs were broadly similar, but DAVCs exhibited a more pronounced late-fall peak. At the county scale, DAVCs were overrepresented relative to WVCs in most of eastern Montana and underrepresented in most of western Montana. WVC and DAVC hotpots did not show strong overlap at the 1-mile road segment scale. Our results suggest that DAVCs warrant greater attention, and they may represent a high priority for management and mitigation measures in some areas because (1) they can be locally common even when regionally rare, (2) they are more dangerous to motorists on a per-collision basis than WVCs, and (3) they can present a legal liability for livestock owners. Mitigation measures for DAVCs may differ from those for WVCs and require further development and testing. Future data collection efforts should include information not only on the location and timing of animal-vehicle collisions, but also on the species of animals killed.