WILD BOAR (Sus scrofa) POPULATIONS IN EUROPE A scientific review of population trends and implications for management Dr. Jurgen Tack European Landowners’ Organization Cover: wild boar © Neil Burton/Shutterstock.com Text and graphs © European Landowners’ Organization/K&DM How to cite this report: Tack, J. (2018). Wild Boar (Sus scrofa) populations in Europe: a scientific review of population trends and implications for management. European Landowners’ Organization, Brussels, 56 pp. Wild Boar (Sus scrofa) populations in Europe A scientific review of population trends and implications for management Dr. Jurgen Tack Scientific Director European Landowners’ Organization (ELO) Pantone 390 CMYK 24 / 0 / 98 / 8 Pantone 364 CMYK 73 / 9 / 94 / 39 European Landowners’ Organization Wild Boar (Sus scrofa) populations in Europe Preface This report is based on 550 peer-reviewed scientific papers containing the words ‘wild boar’ and ‘Europe’ in their abstracts. The research papers are published in the period 1977-2017 and cover a wide range of topics. The systematic growth in the number of scientific publications on wild boar is an indication of growing environ- mental and social concerns about the species, which is in turn a reflection of their increasing presence across Europe. The research shows that wild boar populations are increasing in most areas of Europe. For some, a growing wild boar population is a positive development, indicating better habitat conditions and the presence of an additional huntable species. Others are strongly opposed to an expanding population and cite the increasing negative impacts such as agricultural damage and road accidents. The growing populations can be explained by a multitude of variables including climate change, agricultural practices, and increasing human pressures in rural areas (leisure activities, agriculture, …). While many research papers are trying to explain the reasons for growing populations, and their associated problems, it is hard to find scientific information on possible solutions. This report tries to identify elements which could help manage and limit the negative impacts of the growing wild boar populations. At the same time, it calls for a stronger scientific support of existing and future manage- ment practices. Recommendations given in this report should not be considered as solutions but should be seen as a basis for discussions in order to reconcile nature, social and economic arguments. Janez POTOC˘ NIK Former European Commissioner - DG Environment Wild Boar (Sus scrofa) populations in Europe Contents Introduction 9 Road accidents/vehicle collisions 32 A review of the scientific literature on wild boar in Europe 11 Variables influencing population size 33 Ecology of wild boar 13 Hunting 33 Distribution 13 Hunting practices 34 Social Behaviour 13 Demography 34 Reproductivity 14 Supplementary feeding 35 Species description 15 Climate 35 Mortality 18 Reforestation 38 Habitat 18 Food availability 38 Diet 18 Mast 38 Predators 18 Maize 39 Population densities in Europe 19 Rapeseed 40 Monitoring 19 Mustard 42 Data availability 20 Responses/solutions 42 Population trends in Europe 20 Hunting 42 Impact of wild boar 28 Supplementary feed 43 Human and animal health 28 Fencing 46 Garbage raiding 31 Better support 46 Damage to agriculture 31 Conclusions and policy recommendations 48 Damage to biodiversity 31 References 50 Wild Boar (Sus scrofa) populations in Europe Introduction Wild boar populations have undergone a systematic increase, in both size and distribution range, across most parts of Europe over the past 30 years. The growing number of wild boars has resulted in numerous econom- ic, environmental, and social problems. 9 Hunters, landowners and environmentalists have diverging opinions on the causes of the population growth in Europe, as well as different responses to managing it. Private landowners aim to combine biodiversity objectives with economic activities. However, the damage to agricultural land and forests in recent years due to increased wild boar populations is challenging their com- bined environmental, social and economic business models. To get a better view on the current situation, the causes and effects of these growing populations, and as well as assessing the effectiveness of certain measures which are taken to mitigate negative human-wild boar interactions, we have decided to try to find some answers within the vast amount of scientific papers written on the subject. This report is not a research paper. It is a review of the vast amount of scientific research which exists on the species. Our study is based on peer-reviewed papers published over the past 30 years on the topic of wild boar in Europe and covers a large number of research disciplines. Basing our conclusions on existing knowledge, this study proposes a number of policy recommendations to decrease the number of negative human-wild boar interactions. Dr. Jurgen Tack Scientific Director European Landowners’ Organization (ELO) Wild Boar (Sus scrofa) populations in Europe A review of the scientific literature on wild boar in Europe Across Europe, wild boar populations have been In the last 30 years the scientific literature on wild growing systematically. An increase in the 1960s-1970s boar has been increasing in parallel. This reflects was followed by a period of stabilisation in the 1980s. both the phenomena of fast-growing populations However, recent evidence suggests that numbers of of wild boar in Europe, and the increased concern wild boar have been increasing more rapidly since for the potential economic, environmental and the 1990s (Massei et al., 2014). health-related impact this poses. Numerous scientific disciplines have studied the wild boar in Europe, however there is a clear interest in concerns related to health and environmental is- 1992 sues. The annex to this report contains the abstracts 1993 of peer-reviewed scientific papers on wild boar in Eu- 1994 rope in the period 1977-2017 screened in the frame- work of this report. 1995 1996 This overview is certainly not complete. Besides peer 1997 reviewed scientific papers there is an enormous amount of grey literature on the topic. For this re- 11 1998 view, we have limited the scope to peer-reviewed 1999 papers to give a scientific view on the actual situation 2000 of wild boar in Europe. 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 01020304050607080 Figure 1: the number of peer-reviewed scientific papers per year in the period 1991-2017 on wild boar in Europe (Web of science – topic: wild boar Europe); 2017 up to August VETERINARY SCIENCES ZOOLOGY ENVIRONMENTAL SCIENCES ECOLOGY PARASITOLOGY MICROBIOLOGY INFECTIOUS DISEASES SCIENCE TECHNOLOGY OTHER TOPICS GENETICS HEREDITY AGRICULTURE BIODIVERSITY CONSERVATION PUBLIC ENVIRONMENTAL OCCUPATIONAL HEALTH VIROLOGY BIOTECHNOLOGY APPLIED MICROBIOLOGY EVOLUTIONARY BIOLOGY GEOLOGY PHYSICAL GEOGRAPHY BIOCHEMISTRY MOLECULAR BIOLOGY FORESTRY 12 FOOD SCIENCE TECHNOLOGY ARCHAEOLOGY IMMUNOLOGY ANTHROPOLOGY ENTOMOLOGY LIFE SCIENCES BIOMEDICINE OTHER TOPICS CHEMISTRY PALEONTOLOGY REPRODUCTIVE BIOLOGY GASTROENTEROLOGY HEPATOLOGY GEOGRAPHY RESEARCH EXPERIMENTAL MEDICINE TROPICAL MEDICINE BEHAVIORAL SCIENCES NUCLEAR SCIENCE TECHNOLOGY PLANT SCIENCES TOXICOLOGY 050 100 150 200 Figure 2: the number of peer-reviewed scientific papers per research area in the period 1991-2016 on wild boar in Europe (Web of science – topic: wild boar Europe) Wild Boar (Sus scrofa) populations in Europe Ecology of the wild boar 13 Distribution Due to its extensive distribution, high numbers and considerable adaptability, the IUCN has classified it The wild boar (Sus scrofa) is among the most widely as a species of least concern and it is considered an distributed large mammals in the world (Oliver et al., invasive species in certain areas where it has been in- 1993). The species originated in Southeast Asia dur- troduced (Bieber & Ruf, 2005; Lowe et al., 2004). The ing the Early Pleistocene (Chen et al., 2007) and its species has developed several subspecies. Wozen- natural range extends from Western Europe and the craft (2005) describes 16 subspecies, divided in four Mediterranean basin to Eastern Russia, Japan and regional groups (Western, Indian, Eastern, and Indo- South-east Asia (Sjarmidi & Gerard, 1988). nesian). Its distribution continues to increase worldwide. The species is extremely adaptable, with an enormous Social behaviour reproductive capacity, and can be found through- out a large spectrum of habitat types, ranging from Wild boars are social animals typically living in fe- semi-arid environments to marshes, forests and al- male dominated herds, or sounders. The sounder pine grasslands (Sjarmidi & Gerard, 1988). One of the is led by an older female, or matriarch, and consists reasons for the wider spread of boar populations of interrelated females and their young, of both sex- has been for their meat; wild boar farms have been es. Male boar leave their sounder at the age of 8–15 established in countries where the species had long months. Females remain with their mothers or es- ago been hunted to extinction. The wild boar popu- tablish new territories nearby. Adult males tend to be lation was non-existent in Sweden ten years ago, but solitary outside the breeding season with subadult now an estimated 150,000 individuals are present males sometimes living in small groups (Marsan & the country (Magnusson, 2010). The UK also has a Mattioli, 2013). boar population for the