Animal-vehicle collisions - from knowledge to mitigation

摘要

Road networks and traffic cause worldwide environmental and ecological problems, and collisions with large animals are an increasing traffic safety issue. There is thus a continuous need to improve our understanding of the factors affecting the controversial relationship between nature, traffic, and human welfare, and to develop efficient mitigation measures. In this thesis, I found that population size is the most important factor explaining the yearly variation in the number of moose-vehicle collisions (MVCs) in Finland. The monthly number of MVCs peaked in autumn with a secondary peak in early summer. This pattern differed from Sweden and Norway where the peak occurred in winter. In contrast, the relative risk of personal injuries was highest during summer in each country. Spring weather was found to affect the detailed timing of spring MVCs in Finland: collisions occurred earlier during warm springs. In addition, as the beginning of the growing season has moved to an earlier date in the last two decades, so has the spring MVC peak. In addition to MVCs, several thousand collisions involving deer species other than moose annually occur on Finnish roads. White-tailed deer was found to suffer highest traffic mortality rates in relation to population size, followed by moose, roe deer, and fallow deer. Among the studied species, moose has the largest and roe deer the smallest probability of surviving a collision. The adverse impacts of traffic on animals could be mitigated for example by constructing wildlife passages. Dry paths under road bridges proved to be an effective mitigation measure for reducing the traffic mortality of small and medium-sized terrestrial animals. The results of this thesis underline that different mitigation measures from population management and driver education to structural solutions are needed when trying to reduce the number and consequences of animal-vehicle collisions.