Moose–vehicle collisions occur earlier in warm springs

After autumn, early summer is the most important moose–vehicle collision (MVC) season in Finland. We surveyed temporal distributions and long-term changes in the timing of MVCs using data of daily collisions that occurred throughout a 4-month season (April–July) for the period 1989–2011. By uniting the road districts, we first divided Finland into five study regions and calculated the annual dates by which 50 % of all the MVCs of the study season had taken place (median dates). Then, using all of the present nine road districts as areal units, we determined if the beginning of the growing season and the median dates of MVCs were correlated. A total of 13,233 MVCs occurred during the study period. In every region, considering the selected 4-month annual period, the number of MVCs was the lowest in April but started to increase in May and was highest in June or July. The timing of the median dates for MVCs in all regions shifted to an earlier date and was positively correlated with the beginning of the growing season in every road district. We believe that the beginning of the growing season correlates with the timing of moose spring migration from wintering areas to summer pastures and further, with the timing of MVCs. Regardless of the ultimate reason behind our findings, we emphasize the practical importance of our results, namely how the onset of spring can help predict timing of spring MVCs. We recommend that warning campaigns informing road users coincide with the annually changing MVC season.