Impact of hunting modality on social contacts in wild boar populations across Europe

Variation in animal social interactions emerges from individual responses to social and physical environments and plays a key role in shaping pathogen transmission, gene flow and information transfer. Although hunting can induce changes in contact patterns through disruption of the social environment, the non-consumptive effects of hunting have not received much attention compared to demographic effects of harvest. We examined the effects of hunting activities on contact rates in wild boar, a species particularly exposed to social disruptions owing to its high sociality and intense management. Using GPS-telemetry data from 21 populations across Europe (435 unique dyads), we analysed how hunting activities impact social contacts within and between wild boar groups while accounting for confounders potentially shaping contact heterogeneity (e.g. habitat productivity, population density, predation, seasonality, individuals' sex and spatial proximity). We found that drive hunts, but not individual hunts, lowered contact rates within wild boar groups. Contact rates tended to be negatively related to drive hunts' frequency. We did not observe the effect of hunting mode on contact rates between members of different groups, which was mainly shaped by a positive relationship with spatial proximity. Contact probability among females from different groups was lower compared to male–male or mixed-sex dyads. Synthesis and applications. Our study showcases how hunting disturbance influences social contact rates in a group-living wild mammal. Along with other biotic and abiotic drivers, hunting modality plays a significant role in shaping intra-group, but not inter-group, contacts. Reduced group cohesion induced by drive hunts could negatively impact survival, foraging efficiency, and resource utilization. Hunting management could mitigate those negative impacts by spatially spreading driven areas throughout the season and targeting different groups each time. Our results suggest that hunting disturbances should not enhance disease spread through increased inter-group contacts. Yet, hunting-induced escape movements could still pose a risk of transmission into new areas. Inter-group connectedness appeared to be maintained predominantly by males which could be targeted if disease transmission was a major management objective. Spatial proximity between individuals can be a reliable index of the amount of direct contacts within wild boar populations.