Individual‐Based Models Reveal Population Recovery and Impacts of Woodland Creation on Pine Martens ( Martes martes ) in Britain

ABSTRACT

Individual‐based models (IBMs) predict distribution and abundance patterns resulting from individual life histories. They are useful for simulating spread, particularly in reintroductions, and testing multiple conservation actions. The accuracy of IBMs relies on the parameters used, and recently, calibration methods have been developed to integrate disparate information. We calibrate an IBM for the pine marten ( Martes martes ) in Britain using observed presence/absence data. We then use this model to investigate whether the multiple reintroduction projects in Southwest Britain are likely to coalesce into a single population, and whether woodland creation can be designed to facilitate dispersal. Our calibrated model reveals that some populations in Southwest Britain may remain isolated after 150 years, likely due to a lack of residential habitat between population centres under our definition of suitable habitat. However, they remain successful at a local scale, with populations persisting in all release zones. We find that none of our woodland creation scenarios, which vary in the area and configuration of new patches, increase the abundance of pine martens or their dispersal capacity. Instead, the biggest factor influencing outcomes is the landscape. Our results suggest that realistic tree planting, in particular patch size, is insufficient to benefit pine martens under our model definitions. However, the coarse scale of our model and our definition of suitable patches could underestimate the influence of small woodlands and hedges on population dispersal and viability. We show that the reintroduction of pine martens to England and Wales successfully restores parts of the former range into the near future. Woodland cover is an important factor in landscape carrying capacity, but significant woodland creation may be needed to enact meaningful change. Our calibrated model can support the selection of reintroduction sites with the greatest probability of facilitating population coalescence.