England is once again home to wild beavers, with a group of at least three living along the River Otter in Devon, the first wild beavers in England since the 12th century, when they became nationally extinct due to hunting for their meat and pelts. This has been widely celebrated, with the ability of beavers to maintain wetland and coppice, opening up habitat for a variety of other species, alongside their potential to improve water quality and flood defence cited as reasons to support the presence of wild beavers.
Following this, DEFRA announced that the beavers are to be ‘caught and rehomed’, whichhas, unsurprisingly, been met with seemingly universal public condemnation by those interested in wildlife and ecology, with influential writers adding to the growing calls for these beavers to be left alone and studied. Unlike the polarising nature of the debate on control of badgers, this seems to be a wildlife issue that everyone agrees on. Indeed the badger situation has undoubtedly had an impact on people’s views, with unsubstantiated fears rising that DEFRA intend to cull the animals. This distrust of DEFRA on wildlife issues has been fuelled by the badger debate, and has led to claims that the motivation for removing the beavers if pressure from the Angling lobby, who are worried about the effects of beaver presence on the ability of commercially important fish species moving through streams to reach their spawning grounds. Whilst the Angling Trust are indeed against the reintroduction of beavers, and the current conservative government are rightly questioned over their motivation for many environmental policies, in this case the primary reason for beaver removal is being mostly ignored or dismissed.
DEFRA are right to move to remove these beavers from the wild due to their risk of carrying the tapeworm Echinococcus multilocularis, which causes alveolar echinococcosis, a potentially lethal disease, in humans. This pathogen has a lifecycle usually involving foxes and other carnivores, alongside small mammals, with domestic dogs also able to be infected and carries significant economic and health costs through livestock loss and costs of treatment. The UK is currently free of this pathogen, with steps being taken to ensure this remains the case.
Beavers can carry the pathogen, but this depends on their location. In Scandinavia, the pathogen isn’t present in beavers, but in other areas such as Bavaria, the pathogen is endemic, although at levels of 2.5-5%. In Scotland, where successful beaver reintroductions have taken place at Knapdale, beavers were sourced from Scandinavia to ensure a negligible likelihood of introducing the pathogen to the UK. Reintroductions were also carefully planned for many years and every attempt made to assess the impact of beavers on the local area (as is being done by the Devon Wildlife Trust). Reintroductions and rewilding are excellent methods of species conservation, that have met with great success, but they also come with fundamental risks that must be managed, with pathogen transmission one of the major risks. The issue here is not that beaver reintroduction is a bad idea per se, but that reintroductions must be done properly, with careful consideration made of the impacts. Inadvertent introduction of a novel pathogen to our wildlife could have negative consequences many orders of magnitude higher than the benefits of beavers to a local area. The few who have acknowledged the risk of pathogen transmission have been quick to dismiss the risk, with even notable publications such as The Ecologist referring to the ‘fictitious danger’ of Echinococcus. A recent risk assessment by DEFRA identified the risk of a beaver imported from Bavaria carrying the pathogen as low, and the risk of a beaver from Scandinavia carrying the pathogen as negligible.
It is important to note that no one is certain of the source of these beavers. They could have originally come from Bavaria, with the pathogen, and be in a situation to spread it to other wildlife. Although on balance this is not likely, it is a lot more likely than the risk from proper planned reintroductions of Scandinavian sourced beavers. Live beavers cannot be reliably tested for the pathogen, although recent progress is being made on this front. Whilst the source of the River Otter beavers is unknown, the facts that i) beavers imported from Bavaria (where Echinococcus is present) are captive in Devon and ii) a captive beaver in Devon has been found to carry Echinococcusshould be more than enough to confirm that there is a risk of pathogen spread. Therefore it makes complete sense to capture these animals and rehome them, whilst using the massive public interest in this story to spearhead discussions and debate into the proper reintroduction of beavers into England. It is also important to remember that these animals originated from captivity somewhere, so are not being harshly removed from their wild existence. Simply observing them from a distance is not a valid option given the disease risk, regardless of the uncertain size of that risk. The beavers should be rehomed in captivity, whilst we await the results from Devon Wildlife’s Trust captive beaver project which are due in 2016. Depending on these conclusions work can then begin on a well-planned reintroduction programme. It would be an immense pleasure to see wild beavers in Britain, but this should be done properly to prevent the spread of a damaging disease.
- A,M. Barlow (2011) Echinococcus multilocularis in an imported captive European beaver (Castor fiber) in Great Britain. Veterinary Record (2011) 169, 13; 339
- Cunningham, A. A. (1996) Disease Risks of Wildlife Translocations. Conservation Biology, 10: 349–353.
- B. Gottstein, C.F. Frey, R. Campbell-Palmer, R. Pizzi, A. Barlow, B. Hentrich, A. Posautz, M.-P. Ryser-Degiorgis (In Press) Immunoblotting for the serodiagnosis of alveolar echinococcosis in alive and dead Eurasian beavers (Castor fiber), Veterinary Parasitology, Available online 18 June 2014