The effect of traffic intensity and animal activity on probability of ungulate-vehicle collisions in the Czech Republic

• Traffic intensity is not during all year and on all types of roads the most important cause of ungulate-vehicle collisions.
• Ungulate-vehicle collisions directly correlate with the time when animals have the highest activity.
• Mitigation measures have to be designed in accordance to cycles of animals’ activity.

Traffic infrastructure and its traffic flows has rapidly developed in recent decades. This development brings benefits to society, but on the other hand has many negative impacts on the environment. Among the most significant impacts of road traffic is direct mortality of free-ranging animals due to vehicle collisions.The main aim of this study was to compare the significance of traffic intensity fluctuation and ungulate behavioural patterns with the probability of ungulate-vehicle collisions (UVCs) occurrence in the Czech Republic. Our research question was whether the probability of UVC occurrence is influenced mainly by vehicle traffic related factors (traffic intensity, road types) or by ungulate locomotory activity.We used information on UVCs from 2011 to 2013. We used Spearman’s rank ρ correlation coefficients to examine relationships between UVCs and traffic intensity fluctuation, and between UVCs and the locomotory activity of red deer and wild boar during 24-h cycles in respective months.The results indicate that the traffic intensity is not always the main factor causing the UVCs. A thorough analysis of our data showed that the main peaks of UVCs occur at time when animals have the highest locomotory activity. Our study proves high negative correlation between traffic intensity fluctuation and UVCs on motorways and expressways, which means ungulates tend to avoid crossing roads at peak traffic intensity. Next our study clearly shows that locomotory activity of ungulates is a more important factor in probability of UVC incidence than traffic intensity in the case of first-, second-, third-class roads and other roads.