Addressing challenges for large-scale trophic rewilding

The climate and biodiversity crises are inextricably linked and curbing both requires large-scale ecosystem restoration to be put into practice. In this context, trophic rewilding, which focusses on the restoration of megafauna and their ecological roles, remains a particularly major challenge. Many landscapes across the globe currently have low densities of megafauna or have lost these species altogether. Although some megafauna species have recovered in some places, through both passive and active rewilding, they are often confined to small areas. There is an increasing recognition that protected areas alone may not suffice to retain and recover high trophic complexity over large spatial extents in most of the world. This raises a clear need to scale up rewilding initiatives. Here, we discuss major challenges and potential solutions for such a scaling up of trophic rewilding, including land availability, supportive policies, the supply of animals for translocations and reintroductions, and funding. We illustrate these challenges and opportunities for two cases, the steppes of Kazakhstan and the Mediterranean rangelands. We highlight that ongoing structural change and agricultural abandonment offers opportunities for trophic rewilding in different world regions. Making use of these opportunities would require mainstreaming land-use planning that supports rewilding regardless of the current protection status of landscapes, and a reorientation of subsidies for agricultural activities in marginal lands to supporting restoration efforts. The supply of animals for reintroduction and population reinforcement projects represents another key challenge. This could be supported through a transition from farming to wildlife ranching, combined with ambitious breeding programs for keystone megafauna. Upscaling restoration efforts has recently been agreed upon as a global conservation target, and we here highlight the challenges and opportunities for restoring megafauna and their key role in ecosystems.