Driving in the dark: Deciphering nighttime driver detection of free-ranging roadside wildlife.

• High-beam headlights increased detection probability and detection distances of deer. • The amount of time spent driving decreased detection distances of deer. • Detection probability decreased when deer were in vegetation and not at road level. • Nearly all encounters with wild pigs and small mammals were deemed dangerous. • Most drivers could not detect wildlife at safe distances to avoid a collision. Wildlife-vehicle collisions are dangerous for motorists; however, few studies have addressed driver detection of roadside animals, and none have evaluated detection of free-ranging wildlife. We used 24 volunteer drivers, infrared videography, a 75-km route, and free-ranging wildlife to quantify factors influencing (1) probability of wildlife detection, (2) detection distance, and (3) probability of dangerous encounters (i.e., detection distance < distance required for braking) for multiple species at night in South Carolina, USA. Detection probability of white-tailed deer (Odocoileus virginianus) was impacted by multiple driver, animal, and roadside factors. Deer detection distances increased by 20.99 m when drivers used high-beam headlights and 23.36 m when deer were moving but decreased by 0.71 m for every minute into a drive. Every encounter with wild pigs (Sus scrofa) and most encounters with small mammals were considered dangerous. Our findings suggest most drivers cannot safely detect deer, wild pigs, and small mammals at night. [ABSTRACT FROM AUTHOR]