Does land use within the home range drive the exposure of roe deer (Capreolus capreolus) to two abortive pathogens in a rural agro-ecosystem?

The recent increase in interactions between wildlife and domestic animals has heightened the risks of transmission of pathogens between wildlife, livestock, and humans. Our objective was to better understand how the spatial behavior of wildlife impacts their exposure to pathogens. We carried out a 5-year serological survey of Toxoplasma gondii and Chlamydia abortus in a roe deer population (Capreolus capreolus) living in a rural landscape and monitored using GPS technology. We tested whether the apparent seroprevalence of these pathogens was related to the characteristics of roe deer's home range, indirectly reflecting the probability of contact between deer and domestic hosts (cats for T. gondii and ruminants for C. abortus). We controlled for the effects of temperature and rainfall, as local weather can affect pathogen survival in the environment. Overall, apparent seroprevalences were 43.7 and 15.8 % for T. gondii (N = 135) and C. abortus (N = 133), respectively. The apparent seroprevalence to T. gondii increased with the proportion of human dwellings (a proxy of cat presence) within the roe deer's core home range and was higher during mild and wet years. This result illustrates how the spatial behavior of wild animals can modulate their exposure to pathogens through the degree of spatial overlap with a domestic host. By contrast, apparent seroprevalence to C. abortus increased with the annual number of frosty days but not with the proportion of meadows occupied by domestic ruminants within the core home range. This suggests that the cycle of C. abortus in wild animals could be somewhat independent from that in livestock.