Wildlife-vehicle collisions are a pervasive global issue, posing a threat to both animals and humans. These collisions result from a complex interplay of driver behavior, animal behavior, and environmental factors. Despite contributing to nearly every collision, little is known about the factors that influence driver behavior during wildlife encounters. Furthermore, most mitigation methods are ineffective or impractical to implement widely. This dissertation addressed these gaps by investigating both driver and animal behavior during wildlife-vehicle encounters and evaluating altered vehicle lighting as a potential mitigation method. A literature review revealed that relatively little is known about the factors that influence driver behavior during wildlife-vehicle interactions, with few papers conducting controlled, manipulative studies. Using volunteer drivers and infrared videography, I demonstrated that drivers struggle to detect wild white-tailed deer (Odocoileus virginianus) and wild pigs (Sus scrofa) at safe distances at night. Detection ability improved with increased illumination from high-beam headlights but suffered from fast vehicle speeds and driver fatigue. Focusing on wildlife behavior, I found that altered vehicle lighting can influence captive white-tailed deer behavior during imminent collision scenarios. Specifically, high-beam, halogen headlights without increased frontal vehicle illumination from a rear-facing lightbar had the greatest probability of eliciting an alert response. However, there were large variations in responses among deer, highlighting the difficulty in developing a universally effective mitigation method. Vehicle approaches towards free-ranging deer and wild pigs revealed that vehicle lighting can increase the likelihood of favorable animal responses. Compared to older, halogen headlights, LED headlights largely did not affect deer responses but resulted in earlier avoidance behaviors by wild pigs. Additionally, increased frontal vehicle illumination via a rear-facing lightbar improved responses for both species. Beyond vehicle lighting effects, we also observed large variations in responses among free-ranging deer and wild pigs. Collectively, this dissertation shows that wildlife-vehicle collisions are the result of both maladaptive wildlife behavior and ineffective driver detection ability. Despite this, altered vehicle lighting represents a promising method to reduce collisions by increasing favorable wildlife responses. Overall, this dissertation provides critical insights into a major global concern and offers practical strategies to help improve animal and driver safety.
