Age and spatial effects of <i>Eimeria</i> spp. infections in European hare ( <i>Lepus europaeus</i> ) killed by vehicle collisions

Risk factors for <i>Eimeria</i> infections are well documented in farm and pet animals, but studies focusing on wildlife species are less common. This research aimed to investigate the impact of selected demographic and environmental factors on the prevalence of <i>Eimeria</i> in the European hare (<i>Lepus europaeus</i>). Additionally, we analysed whether <i>Eimeria</i> infection affected the behaviour of hares by examining the relationship between infection status and the likelihood of a hare being killed by a vehicle at a hotspot for road mortality. Between 11 February 2022 and 24 June 2024, we collected 22 hare carcasses that had been killed in traffic along an 83.9 km monitoring route in central Bohemia, Czech Republic, to evaluate <i>Eimeria</i> prevalence in relation to factors such as age, hare density, distance to the nearest water source and rainfall over the previous 3 months. Contrary to our expectations, we found a higher prevalence of <i>Eimeria</i> in adult hares compared to juveniles. We propose that this outcome may be due to the high mortality rates among leverets and juvenile hares, which removes susceptible individuals from the population early on. The effects of the other factors examined were not significant. In conclusion, our study revealed that <i>Eimeria</i> infection did not contribute to the clustering of hare-vehicle collisions. We emphasize the importance of studying risk factors in wildlife species across different ecological contexts. Our findings challenge the general assumption that age negatively influences <i>Eimeria</i> prevalence.