Eurasian beaver (Castor fiber) health surveillance in Britain: Assessing a disjunctive reintroduced population

Background: Numerous translocations of Eurasian beavers have occurred with little implementation of standardised health screening. Pre-release health screening enables the selection of individuals with the best survival prospects and reduces potential health risks, but this is by-passed during unofficial releases. Beaver reintroduction to Britain has been haphazard and currently disjunctive populations of varying status exist. Methods: This observational cross section study investigated the health status of three beaver populations, with 90 live beavers tested for a range of pathogens comprising 56 from Tayside (unofficially released Scotland), nine from Knapdale (officially released Scotland) and 25 from Devon (unofficially released England). In addition, a further 32 cadavers were screened (25 from Tayside and seven from Knapdale). Results: All beavers were in good physical condition, did not harbour any non-native disease or parasites of concern and demonstrated remarkably low levels of any disease or parasite exposure. Conclusion: Beavers are establishing and adapting well to British landscapes and are not acting as reservoirs of significant zoonotic diseases. Official, licensed reintroduction programmes may appear overly convoluted; however, reputational damage of unofficial releases should be considered, along with the health and welfare of the animals involved and collateral damage to other wildlife, domestic animals and humans.