Introduction: Rewilding Ecosystem Services, Not Only Vertebrate Populations
Although the concept of “rewilding” is usually associated to restoring populations of symbolic species, it is obvious that it cannot be understood without the parallel amendment to the structure and functioning of ecosystems (see Chap. 1). In this sense, there are some ecological processes transverse to habitat structure, ecosystems and biomes, which are key to maintaining both complex food webs and the viability of populations of organisms. The large avian scavengers in Europe could serve as a paradigmatic case in this regard. Due to the early and rapid transformation of European landscapes, the decline of large scavenger populations occurred prior to that on other continents (Bijleveld 1974), thus breaking the ancient alliance between traditional agro-pastoral practices and the existent large populations of these birds. However, since the late 20th century to today, it is precisely in Europe that some of the most representative and healthiest populations of vultures and other Old World avian scavengers likely reside, in comparison to other locations where a massive population declines have occurred, such as in Africa and Asia. It is also in Europe where there are likely more active recovery programmes devoted to conserving scavenger' populations mainly based on reintroductions and renewed recognition of the ecosystem, cultural and economic services that scavengers may provide.
Thus, it may be deduced that the rewilding of Europe, specifically in the case of avian scavenger species, has already begun. This process is often accompanied by profound changes in the carrying capacity of the environment (e.g., through supplementary feeding programs). While undeniably profound changes are occurring that may make the maintenance of populations of birds of prey and the services they provide unstable, it is expected that in a few decades large areas of the European continent will abandon traditional grazing activities (see Chap. 1). On the other hand, other regions will continue the intensive occupation and use of land, which may impose potentially greater impacts on natural systems (e.g., agricultural intensification, growth of urban areas) (Deinet et al. 2013).
In this chapter, our goal is to explore, on the basis of existing information, how top scavengers fit into a wilder Europe. To do this, we first examine the role of availability of carrion resources in the maintenance of ecosystem functioning. Then, we examine the implications of the creation of supplementary feeding stations (socalled vulture restaurants). In addition, we will describe how the relationship between humans and vultures has evolved, identifying ecosystem services provided by these charismatic species from the past to the current date. Finally, we propose that the conservation of top scavenger species and the maintenance of natural complex ecological process linked to the exploitation of unpredictable carrion resources in rewilding the European landscapes should rely on favouring wild ungulates expansion, the recovery of predator populations and the promotion of traditional extensive grazing practices.