Expert-based assessment of rewilding indicates progress at site-level, yet challenges for upscaling

Rewilding is gaining importance across Europe, as agricultural abandonment trajectories provide opportunities for large-scale ecosystem restoration. However, its effective implementation is hitherto limited, in part due to a lack of monitoring of rewilding interventions and their interactions. Here, we provide a first assessment of rewilding progress across seven European sites. Using an iterative and participatory Delphi technique to standardize and analyze expert-based knowledge of these sites, we 1) map rewilding interventions onto the three central components of the rewilding framework (i.e., stochastic disturbances, trophic complexity and dispersal), 2) assess rewilding progress by quantifying 19 indicators spanning human forcing and ecological integrity, and 3) compile key success and threat factors for rewilding progress. We find that the most common interventions were keystone species reintroductions, whereas the least common targeted stochastic disturbances. We find that rewilding scores have improved in five sites, but declined in two, partly due to competing socio-economic trends. Major threats for rewilding progress are related to land-use intensification policies and persecution of keystone species. Major determinants of rewilding success are its societal appeal and socio-economic benefits to local people. We provide an assessment of rewilding that is crucial in improving its restoration outcomes and informed implementation at scale across Europe in this decade of ecosystem restoration.