Olfactory repellents decrease the number of ungulate-vehicle collisions on roads: Results of a two-year carcass study

Area of Science:

• Wildlife Ecology
• Road Ecology
• Conservation Science

Background:

• Ungulate-vehicle collisions (UVC) pose significant risks to wildlife and human safety.
• Current mitigation strategies for UVC have limitations, necessitating innovative solutions.

Purpose of the Study:

• To evaluate the effectiveness of olfactory repellents (ORE) as a novel mitigation measure to reduce UVC.
• To quantify the reduction in UVC attributable to ORE application.

Main Methods:

• A Before-After Control-Impact (BACI) study design was employed over two years (2021-2022).
• 134 road sections were monitored weekly for ungulate mortality.
• ORE were applied to impact segments in the 'After' period (2022).
• Bayesian inference was used for statistical analysis to address uncertainty.

Main Results:

• A preliminary decrease of 68% in UVC was observed.
• Bayesian analysis indicated a statistically significant reduction in UVC by 43% to 60%.
• The efficacy of ORE diminished over time, suggesting potential ungulate habituation.

Conclusions:

• Olfactory repellents (ORE) show promise as an effective, albeit temporary, safety measure for reducing UVC on secondary roads.
• Optimal application timing should consider UVC peaks to maximize effectiveness.
• Further research into habituation and long-term efficacy is warranted.