March or get infected: Influence of winter ranging shaped by supplementary feeding on the spread of non-native nematode Ashworthius sidemi in European bison populations

Parasitic infections in wildlife are influenced by numerous factors, including those related to wildlife management. This includes sup plementary feeding widespread in numerous ungulates, including European bison. In this paper we analysed the influence of sup plementary feeding and winter ranging of European bison herds on the dynamics, prevalence and infection severity of the blood-sucking nematode Ashworthius sidemi in two areas in NE Poland: the Knyszyn Forest (KF) and the Bialowieza Primeval Forest (BPF) with diversified management stra-tegies. We found significant differences in A. sidemi abundance and intensity between European bison groups; sup plementary fed European bison from the BPF had higher parasitic load (3020 parasites, on average), than non-fed individuals from the KF (1400) and from the BPF (770). The prevalence was relatively high in all groups (93-96 %). In the KF the highest infection rate was observed 9 years after the first appearance of A. sidemi, with a maximum value of 8,620 nematodes; while in the BPF, after just 6 years with maximal load up to 44,310 A. sidemi. The most plausible mechanism behind the observed pattern is probably the winter ranging behaviour of differently managed herds. We found that increasing winter home range size of European bison was associated with a significant reduction in the A. sidemi abundance. Our study shows that different management strategies may have an impact on animal spatial behaviour and associated spread and dynamics of pathogens in mammalian populations, and stresses the importance of adaptive management in reducing threats to wildlife.

Automated summary

Parasitic infections in wildlife are influenced by factors related to wildlife management, such as supplementary feeding and winter ranging behavior. This study analyzed the impact of supplementary feeding and winter ranging of European bison herds on the infection dynamics and severity of Ashworthius sidemi, a blood-sucking nematode. The results showed that European bison fed with supplementary feeding had higher parasitic load compared to non-fed individuals, and different management strategies influenced the spread and dynamics of the parasite.