Trophic rewilding in Europe has one great advantage and one great disadvantage. The great advantage is that most of the large native mammals that have gone extinct in Europe survive in some form which is ecologically equivalent. The great disadvantage is the comparatively low number of large natural areas with low population densities. This lack of space leads to higher conflict between humans and large animals, somewhat negating my first point about the high potential for megafauna translocation in Europe. Without large natural spaces where human interaction with these species is optional, our capacity to restore ecological function is severely limited. As a consequence, European rewilding initiatives need to be creative in order to balance the need for large herbivores and carnivores in a properly functioning landscape with the inevitable presence of human activity.

One strategy would be to adopt a system similar to the South African model, wherein fenced reserves are used to keep some of the more conflict-prone species from leaving the area, where they might conflict with humans or their livestock. In a European context it would perhaps not be necessary to employ the sort of electric fences required to keep elephants and lions within the confines of the reserve. It would be possible instead to design fences that can keep larger animals like bison (Bos bison bonasus) and horse (Equus caballus ssp) in but allow smaller animals like roe deer (Capreolus capreolus) and boar (Sus scrofa), or animals with better jumping or climbing abilities like red deer (Cervus elaphus) and ibex (Capra sp), to pass more freely. This solution brings its own problems since the construction of such fences would be prohibitively expensive in many cases, and they would do little to prevent the movement of European large carnivores in and out of reserves. Jackals (Canis aureus), wolves (Canis lupus), wolverines (Gulo gulo), and lynx (Lynx lynx) are of a similar size to deer and boar, and bears (Ursus arctos) have the ability to climb fences. One might also question whether or not projects using this strategy could really be called rewilding since they would employ a sort of captivity in order to mediate conflict. I would say that, since animals involved would still be ecologically functional in a near-natural habitat, it would still fill some definitions of rewilding, a notoriously subjective term. I think it is also worth considering that many existing human obstacles already place very strict limits on the dispersal potential of large mammals, even if they do not employ anything so obvious as a fence. This would be a compromise that would perhaps allow for a greater density and diversity of megafauna in European ecosystems than could be accomplished otherwise.

Such issues become even more problematic when deciding an appropriate baseline for rewilding European natural areas. Typically a historic baseline is used or less often an early-mid Holocene baseline, a period lasting from around 12,000 years ago to around 4,000 years ago. Using these does allow for the repatriation of many large mammals to regions where they have been extirpated, but often baselines are chosen out of convenience, based on what local society can tolerate. These baselines would also allow for many species to be present in areas of Europe that we do not traditionally associate them with. The early Holocene saw chamois (Rupicapra pyrenaica) in southern Spain, ibex (Capra ibex) in Bulgaria, wild ass (Asinus hemionus) in Hungary, and saiga antelope (Saiga tatarica) in Romania. Using a Holocene baseline would also allow for lions (Panthera leo) and leopards (Panthera pardus) in the Balkans. Obviously we need to acknowledge the role of humans in eliminating these species from these regions, but we also have to be practical about how we try to reverse this trend. One small thing we can do is acknowledge the evolutionary history of some species that are treated as invasive, often unfairly. For example, fallow deer (Dama dama), mouflon (Ovis musimon), raccoon dog (Nyctereutes procyonoides), macaque (Macaca sylvanus), rabbit (Oryctolagus cuniculus), and porcupine (Hystrix cristata) have all been introduced to areas of Europe outside their historic range, but all come from lineages with extensive histories on the continent from previous interglacials, when conditions and fauna were not so different. In light of this, it is perhaps more prudent to assess the ecological impact of each species individually and determine whether they are worth the expense and effort to remove, especially since such a task may not be feasible.

Flexible baselines are already in use in some areas of Europe. Water buffalo (Bubalus sp) have not been present in Europe since the Pleistocene, save for some dubious Holocene records in Romania and some more concrete one in the Caucasus. Despite this, domestic buffalo are extensively used in wetland conservation projects across Europe. This is because their benefits as natural grazers are recognized and because they are docile and easily handled, but it would seem that they have potential not just as conservation tools but potentially as a native taxon in their own right. Certainly, their role is conspicuously distinct from bison and cattle, with which European buffalo were once sympatric, and they provide numerous benefits to ecosystems where they are employed. Why then should we not consider them as a palaeo-autochthonous lineage, able to return to a role not yet filled after a long absence? I am sure there are many arguments as to why we should or should not, but that is less important than having the conversation in the first place. Our current ideas of what species are and are not native will need some major restructuring in order to effectively combat European biodiversity loss. Traditional baselines may not be so useful in this regard, and a more elastic understanding of existing and prehistoric niches will be necessary in order to create European ecosystems with a diversity and productivity that more closely resembles their prehistoric state.

Of course, the use of prehistoric baselines also requires several additional factors be taken into consideration. One is that large herbivores require large carnivores in order to avoid overpopulation. Wolves are Europe’s current most effective predator of large mammals, after humans, and these are quite effective at controlling anything as large or smaller than a red deer. However, animals like bison and horse were likely only occasionally hunted by wolves and more often hunted by humans. In prehistoric times, before humans became more populous, large-bodied mammals of that size would also have routinely been hunted by large cats (Panthera sp) and by hyenas (Crocuta crocuta). This presents an issue for rewilding European areas today. If wolves and other European predators cannot be relied on to control populations of bovines and horses, we would become dependent on population control by humans. In order for this to be effective, there have to be people who are incentivized to hunt these animals, whether as an occupation, for sport, or for subsistence. Culling by staff requires money for salaries and resources, culling by sport requires a sufficiently interested clientele, and culling for subsistence requires demand for the meat products of these animals. The first is expensive, the second and last are unreliable, and all are completely antithetical to the central rewilding credo of minimum intervention and maximum natural process. Does that instead mean we should instead investigate the return of larger carnivores? That opens up a whole new bag of worms, but it is an issue that may eventually have to be addressed.

Ultimately, I think any rewilding project that does not acknowledge and seek to repair the extreme defaunation that has been occurring on Earth for the past fifty millennia at the hands of human beings, is doomed to restore something to a state where it was already broken. Shifting baseline syndrome does not only occur from decade to decade, it is a phenomenon that spans generations and eras. People whose ancestors hunted aurochs now have no idea what an aurochs is. The same people think of great auks and giant elk in the same way they think about dinosaurs when they think about them at all. Environmental ignorance is a huge barrier to the implementation of environmental solutions, rewilding being no exception. In the future, it will be increasingly necessary to educate people not only on why it is important to return large mammals to Europe but also why they disappeared in the first place. I remember being very surprised to learn that Eurasia, Australia, and the Americas, were once not so different from Africa in their collections of megafauna and that curiously this stopped being the case when humans began arriving in these areas. So why was I not taught that? Why is that something I learned from studying footnotes as an adult? I think if people were generally more aware of how long these extinctions have been going on for, and how utterly devastating they have been for ecological function, they would be more open to trying to restore some of what we have lost. As it stands we are in a situation where we have to explain a quarter-million years of our past every time we want to improve our present.