Effects of Food Addition and Helminth Removal on Space Use and Spatial Overlap in Wild Rodent Populations

Animal space use and spatial overlap can have important consequences for pathogen transmission. Identifying how environmental variability and inter-individual variation affect spatial patterns to drive transmission heterogeneity in wildlife is a priority for effective management of wildlife disease. However, there are few experimental studies investigating how food abundance and macroparasite infection affect transmission opportunities in wildlife. Wild bank voles (Myodes glareolus) are a useful study system to investigate spatial patterns of wildlife and are amenable to experimental manipulations. We conducted a replicated, factorial field experiment in which we added food and removed helminths in wild vole populations in natural forest habitat and monitored vole space use and spatial overlap using capture-mark-recapture methods. Using a combination of home range and network analyses, we quantified vole space use and spatial overlap. We then compared the effects of food addition and helminth removal and investigated the impact of season and sex on space use and spatial overlap. We found that space use was impacted by breeding season and sex but not by food addition or helminth removal. Sex-based, seasonal changes in shared space use were more notable with food addition. Food addition also increased the frequency of, and variability in, spatial overlap occurring between individual voles at trapping locations, while helminth removal had no effect. Our work provides empirical evidence quantifying the spatial effects of food abundance and macroparasite infection on wildlife populations. We demonstrate the potential for high food abundance to increase spatial overlap relevant for pathogen transmission. Our findings also suggest that individual contributions to transmission may be heterogeneous within populations and that season and sex are important covariates to consider when identifying when and with whom transmission is most likely to occur.