SHORT COMMUNICATION What does the wild boar mean to the wolf? Emiliano Mori 1 & Ludovica Benatti 1 & Sandro Lovari 1 & Francesco Ferretti 1 Received: 26 June 2016 /Revised: 21 September 2016 /Accepted: 30 November 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract Generalist predators are expected to shape their diets according to the local availability of prey species. In turn, the extent of consumption of a prey would be influ- enced by the number of alternative prey species. We have tested this prediction by considering the wild boar and the grey wolf: two widespread species whose distribution ranges overlap largely in Southern Europe, e.g. in Italy. We have reviewed 16 studies from a total of 21 study areas, to assess whether the absolute frequency of occur- rence of wild boar in the wolf diet was influenced by (i) occurrence of the other ungulate species in diet and (ii) the number of available ungulate species. Wild boar turned out to be the main prey of the wolf (49% occur- rence, on average), followed by roe deer (24%) and live- stock (18%). Occurrence of wild boar in the wolf diet decreased with increasing usage of roe deer, livestock, and to a lower extent, chamois and red deer. The number of prey species did not influence the occurrence of wild boar in the wolf diet. The wild boar is a gregarious, noisy and often locally abundant ungulate, thus easily detect- able, to a predator. In turn, the extent of predation on this ungulate may not be influenced so much by the availability of other potential prey. Heavy artificial reductions of wild boar numbers, e.g. through numerical control, may concentrate preda- tion by wolves on alternative prey (e.g. roe deer) and/or livestock, thus increasing conflicts with human activities. Keywords Large carnivores . Feeding ecology . Human-wildlife conflict . Predator-prey relationships . Ungulates Introduction The composition of prey communities is expected to influence the diet of predators (e.g. Sinclair et al. 2003; Garrott et al. 2007; Baudrot et al. 2016). In turn, large carnivores play a pivotal role in ecosystems, as their action may generate cascading effects on lower trophic groups (e.g. Fortin et al. 2005; Beschta and Ripple 2009; Suraci et al. 2016). Feeding habits have evolved to max- imise fitness and subject to constraints imposed by availability of food resources (MacArthur and Pianka 1966). Generalist preda- tors are expected to shape their diet according to the local avail- ability of prey species (Terraube et al. 2014; Baudrot et al. 2016). The wild boar Sus scrofa is the most widespread ungulate in the world, favoured by its ecological plasticity, popularity as a game species and particularly high reproductive rate (Barrios- Garcia and Ballari 2012; Massei et al. 2014). In Europe, its main predator is the grey wolf Canis lupus (Newsome et al. 2016), a generalist carnivore (e.g., Mech 1970; Okarma 1997; Davis et al. 2012) which feeds mainly on meso-large mammals, especially ungulates (Meriggi and Lovari 1996; Meriggi et al. 2011; Newsome et al. 2016). In the last few decades, because of reintroductions and improved management (Apollonio et al. 2010), numbers of wild ungulates have increased all over Europe and have been the main determinants of range expan- sion and population growth of the wolf (Okarma 1997; Chapron et al. 2014; Galaverni et al. 2015). When wild prey is available, the wolf tends to prefer it to livestock (Meriggi and Lovari 1996). In particular, the wild boar is an important prey in Mediterranean countries, with variable frequencies of occur- rence across areas (e.g. Meriggi et al. 1996; Barja 2009; Bassi * Sandro Lovari lovari@unisi.it 1 Research Unit of Behavioural Ecology, Ethology and Wildlife Management - Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100 Siena, Italy Eur J Wildl Res DOI 10.1007/s10344-016-1060-7