Rooting for Rewilding: Quantifying Wild Boar's Sus scrofa Rooting Rate in the Scottish Highlands

Rewilding is emerging as a promising framework within restoration ecology to help restore ecosystem function through species reintroduction. To manage effectively such projects it is necessary to predict and quantify the interactions between the reintroduced species and their environment. To date, this has not been a priority in restoration ecology. Here, we quantify wild boar's rooting rate at a range of stocking densities to explore their potential to aid the restoration of the Caledonian pine forest in the Scottish Highlands by reinvigorating the disturbance regime. Eleven enclosures of c. 0.5ha within heather moorland, dominated by Caluna vulgaris, were used, situated on the Alladale Wilderness Reserve, 50km north-west of Inverness. Stocking densities varied between 4 and 15 boar/ha. The accumulation of rooted area was recorded weekly over a 13-week period. A cost analysis was performed to compare the use of wild boar with other ground preparation techniques. The median per capita rooting rate was 42.4m2/week (interquartile range [IQR] 45.5), but rooting rate varied temporally. Median rooting rates varied between 21.6 and 75.3m2/week (IQR 5.6) in periods that varied in suitability for rooting. Rooting rates were consistent across stocking densities. The cost of using wild boar as a ground preparation tool ranged between 184 pound and 1,961 pound per hectare depending on stocking density and rate of rooting. This experiment has direct application for managing the impact of wild boar within free range farming conditions, managed woodland regeneration schemes, rewilding projects, and in the wild.