Projecting population dynamics and range expansion of reintroduced wild boar in Scotland using agent-based modelling

Abstract

The number of species reintroductions is increasing globally via both legal and illegal routes. These reintroductions can be controversial with uncertain social-ecological outcomes, particularly for unsanctioned illegal releases, which risks causing conflict between stakeholders. Despite this, current reintroduction science is focused on short-term population establishment, with little long-term modelling of reintroduced populations. In this study, we develop an agent-based model (ABM) to simulate the controversial reintroduction of wild boar in Scotland. The ABM uses probabilistic birth, death, and movement rules from the literature to stochastically simulate boar population dynamics from their initial release to 50 years in the future. Model evaluation demonstrated that the ABM behaves in predictable and explainable ways, whilst reproducing real boar behaviours and aligning with the spatial distribution of boar sightings in Scotland. Projecting the ABM 50 years into the future suggests that current boar populations are likely viable and will continue to grow and expand, with the model confirming the existence and long-term persistence of four boar populations. We conclude by commenting on the potential future uses of the ABM.