Summary

The 1998 report by the Central Science Laboratory to the Ministry of Agriculture, Fisheries and Food confirmed that there are free living populations of wild boar on the Kent/East Sussex border and also in Dorset; subsequent information suggests another small population near the Forest of Dean. The Mammal Society cautiously welcomes this return of a native species to the wild mammal fauna of Britain.

The Mammal Society acknowledges that responsible reintroductions should take place within the framework of the IUCN guidelines. The Mammal Society recognises that such accidental reintroductions can have positive and negative effects and accepts that further work is urgently needed with regard to the size and management of these populations and their potential effect on the British countryside in the long term. Depending on the outcome of such work, this welcoming position might need revision.

History

The wild boar, Sus scrofa, is a native British species. It probably became extinct as a wild species at the end of the 13th century (Yalden 1999). After this date wild boar were maintained for game and as a status symbol by introduction of new stock from France and Germany and through hybridisation with domestic and feral pigs. By the 17th century no wild boar were found in Britain, suggesting that the medieval reintroductions were not successful, possibly because of hunting pressure.

Despite the failure of the medieval reintroductions, populations of wild boar have now established themselves in the south of England. A report by Central Science Laboratory (CSL 1998), commissioned by the former Ministry of Agriculture Fisheries and Food (MAFF), confirmed the presence of small populations in the Kent/East Sussex borders and in Dorset. Stock from Europe has been imported to Britain for specialist farms, and it is believed that the populations in the wild derive from unintended escapes of such stock.

Legal requirements

Article 11 of the Bern Convention (European Union 1982) requires member states "to encourage the reintroduction of native species of wild flora and fauna when this would contribute to the conservation of an endangered species". It is unlikely that wild boar falls under this article, as it is not an endangered species in Europe; indeed it is regarded as a pest in many agricultural areas. However, as a native species The Mammal Society would in principal like to see wild boar re-established in this country. Legally, wild boar is not currently listed in UK legislation as a game species. If these populations are allowed to develop, legislation must be revised, to formalise the legal requirements covering use of firearms (minimum calibre, shooting seasons and times). It is listed under the Dangerous Wild Animals Act 1976, which requires keepers to be licensed. Wild animals belong to no-one, and it is unclear whether the presence of a potentially dangerous wild animal on land might render landowners liable in some circumstances.

English Populations

The report by CSL concludes that there are two populations of free living wild boar in England, one of 200-300 on the Kent/East Sussex border and one of < 50 in Dorset (CSL 1998, Wilson 2003). Anecdotal information indicates that there may be a third small population, in the Forest of Dean. From carcasses that were examined, CSL has not yet concluded that the populations are of wild-type wild boar rather than hybrids. If they are truly wild boar then The Mammal Society welcomes the news. However, we feel that further, genetic, work is urgently needed to confirm this conclusion. Genetic work in Europe has confirmed, by analysis of mtDNA, that modern domestic breeds of pig include genes from Chinese pigs, the result of 19th century breeding experiments (Kim et al. 2002, Alves et al. 2003). If wild boar have been crossed with modern breeds, this should therefore be readily discernible. Some ancient breeds are not very different from wild boar, and hybrids from these, especially the old European domestic pig strains, may be harder to detect. Little conservation interest would be attached to a population of feral domestic pig crosses, if that is what they should turn out to be.

Benefits and problems

Agriculture

The rooting behaviour of wild boar at their natural carrying capacity can cause considerable agricultural damage (Schley and Roper, 2003) but whether this currently leads to economic loss in the UK has yet to be confirmed. It has also been reported that agricultural damage is correlated with mast production; wild boar preferentially consume acorns and beech mast when available, and consumption of agricultural crops is only likely to occur in years of poor natural food supply (Schley and Roper, 2003).

A more likely risk to farming is the possibility of disease transmission to domestic stock. Wild boar have been known to visit domestic pig sows in Dorset and Kent, resulting in hybrid piglets (CSL 1998). If a disease that currently only occasionally occurs in Britain such as Classical Swine Fever (CSF), Foot-and-Mouth or Aujeszki’s Disease passed from domestic stock to wild boar, they could then act as a reservoir for the disease and continually re-infect domestic stock. The economic consequences of this could be severe. CSF is currently present in some wild boar populations in certain parts of Europe and it has been demonstrated that they act as a reservoir for infection; during outbreaks among wild boar, the disease has been passed to domestic stock (Scientific Committee on Animal Health and Welfare, 1999) To decrease the likelihood of this happening it is important that fencing, handling and transport of both domestic pig and wild boar stocks is extremely secure, decreasing the possibility of transmission from herds to free living wild boar. Secure fencing is also important to reduce the possibility of free-living wild-type wild boar being contaminated by domestic escapes. Currently wild boar do not occur in areas with substantial domestic pig rearing. Steps should be taken to ensure that this continues to be the case.

Nature Conservation

Although wild boar are an important addition to the wild mammal fauna of Britain, their re-establishment could have positive or negative effects for nature conservation, especially in our more ancient woodlands. Wild boar rooting behaviour could impact on the diversity of woodland flora (Leaper et al, 1999) and on specific species such as the lady orchid, Orchis purpurea (found in Kentish woodlands) and the bluebell, Hyacinthoides non - scripta. British bluebell woodlands are unique, scarcely matched elsewhere in Europe, perhaps due to the lack of soil disturbance in Britain by wild boar. However wild boar rooting could be beneficial in the control of bracken through the destruction of its rhizomes and certain habitats have a greater species diversity as a result of wild boar rooting activities (Leaper et al, 1999)

It is true that wild boar co-existed with these woodlands before the wild boar became extinct at the end of the 13th century but what their reintroduction after 700 years of absence will mean is unknown. Environmental Impact Assessments (EIA) carried out in Europe, Australia and USA have been contradictory in that wild boar have sometimes been found to reduce the number of plant and animal species but elsewhere to increase the biodiversity of plant species. Part of these contradictions arise from the fact that wild boar is not native in some of these countries (e.g. Australia and USA) and because they can reach unnaturally high densities in these countries due to the presence of crops and the absence of natural predators.

Population Size

The CSL report also includes computer modelling of population size and the geographical area over which it may extend. They conclude that the populations will continue to grow, slowly at first but, in the absence of their natural predators (bear and wolf), this rate could increase. This could be exacerbated if these animals are hybrids, given the greater fecundity of hybrid stock (CSL, 1998). On the continent wild boar numbers are often controlled by hunting (with a sustainable harvest of 0.4 million taken from a population of 0.5 million; Myberget 1990), the revenue being partly used to compensate for agricultural damage. It is unlikely that the less-wooded British countryside could support the number of wild boar seen on the continent but the controlled legislated hunting of wild boar as a method of population control and to bring in revenue could be a possibility. Evidence from both Dorset and Kent/Sussex suggests that culling rates are currently sufficient to limit population increase.

Further work

Culling has failed to control deer populations in Britain adequately. Adequate monitoring of the boar population, and modelling to determine the culling regime required to prevent range expansion, is essential. In the event of a disease outbreak, local eradication might be needed. The possibility of trialling this in one of the populations should be considered.

The Mammal Society believes that further work is needed to determine the exact nature of the populations of wild boar living in the South of England. If they are of wild-type wild boar, then this re-establishment of a native species is to be welcomed. If they are hybrids then careful consideration needs to be given to their removal.
If they are hybrids to be removed, the reintroduction of genetically true wild boar can be planned following IUCN guidelines, with public consultation and proper preparation of suitable sites. It is unlikely that the sites where wild boar have re-established themselves are those that would have been chosen for a controlled re-introduction. It is therefore necessary that further work on the possible consequences of this re-establishment on agriculture and conservation in the South of England is carried out. Discussion of this issue needs to consider the evidence from Europe, e.g. from vets, conservationists and foresters, on how to manage a large mammal in a densely farmed landscape. Further work is also needed to assess the public’s opinion on this re-establishment (DEFRA has as a model the excellent consultation carried out by Scottish Natural Heritage on their proposed reintroduction of the European Beaver to Scotland). There has been some concern in the South of England about public safety in relation to wild boar (Wilson, 2003) and also the likelihood of attracting an irresponsible shooting element - carrying out unauthorised shooting in unsuitable areas using unsuitable weapons. For the reestablishment of wild boar to be successful, there needs to be a systematic programme to disseminate information to the public about wild boar, a planned policy devised in an educated manner, and legislation to recognise the wild boar as a game species. A formally agreed management (culling) programme, involving local landowners, farmers and game-dealers, should be part of this programme.

The Mammal Society thus agrees with the need for further work that is outlined in paragraphs 158 and 159 in the CSL report to MAFF, but this should include modelling of the resources necessary to prevent a nationwide spread. The legal aspects, including recognition of wild boar as a game species, also need attention.

References

Alves, E., Ovillo, C., Rodriquez, M.C. & Silio, L. 2003. Mitochondrial DNA sequence variation and phylogenetic relationships among Iberian pigs and other domestic and wild pig populations. Anim. Genetics 34: 319-324.

Central Science Laboratory 1998 - Current Status and Potential Impact of Wild Boar (Sus scrofa) in the English Countryside: A Risk Assessment. MAFF, Nobel House, Smith Square, London

Scientific Committee on Animal Health and Animal Welfare. 1999 Classical Swine Fever in Wild Boar. European Commission, XXIV/B3/R09/1999. http://europa.eu.int/comm/food/fs/sc/scah/out24_en.pdf

Leaper, R., Massei, G., Gorman, M.L. and Aspinall, R. 1999 The feasibility of reintroducing Wild Boar (Sus scrofa) to Scotland. Mammal Review, 29, 4, 239-260

Kim, K-I., Lee, J-H., Li, K., Zhang, Y-P., Le, S.S., Gongora, J. & Moran, C. 2002. Phylogenetic relationships of Asian and European pig breeds determined by mitochondrial DNA D-loop sequence polymorphism. Anim. Genetics 33: 19-25.

Myberget, S. 1990. Wildlife management in Europe outside the Soviet Union. NINA Utredning 018: 1-47.

Schley, L. and Roper, T.J. 2003 Diet of wild boar Sus scrofa in Western Europe, with particular reference to consumption of agricultural crops. Mammal Review, 33, 1, 43-56

Scottish Natural Heritage 1998 - Re - introduction of the European Beaver to Scotland - a public consultation.

Scottish Natural Heritage, Redgorton, Perth.

Wilson, C. 2003. Distribution and status of feral wild boar Sus scrofa in Dorset, southern England. Mammal Review 33: 302-307.

Yalden, D.W. 1999. The History of British Mammals. T. & A.D. Poyser, London.