Beaver Reintroduction Research Articles

Re-establishing historic ecosystem links through targeted species reintroduction: Beaver-mediated wetlands support increased bat activity

Despite the global significance of wetlands, conservation strategies often fall short in preserving these ecosystems due to failures in incorporating processes that sustain the ecosystem functioning, hydrological dynamics, ecological processes, and biodiversity of wetlands. Nature-based solutions, such as the reintroduction of beavers, have emerged as effective tools for promoting wetland restoration. Whilst the impact of beavers on wetland restoration is well known, their broader influence on ecosystem health, particularly in modifying habitats for other species, remains inadequately understood. Here we assess the impact that habitat modification through the reintroduction of beavers has on bat populations. There were significantly greater activity levels within beaver-modified wetland habitats for multiple bat species, including higher activity levels of 393 % for Barbastella barbastellus and 313 % for Plecotus spp.. Additionally, we observed positive effects on bat populations in the woodland habitat surrounding beaver-modified wetland for certain taxa. In the face of escalating challenges posed by climate change and habitat loss, addressing biodiversity loss necessitates a shift toward ecosystem-centric mitigation measures. Our study demonstrates that the reintroduction of keystone species like beavers can re-establish historical facilitative links between aquatic and terrestrial food webs, highlighting the importance of such interventions in fostering the resilience and sustainability of entire ecosystems.

The genetic legacy of the first successful reintroduction of a mammal to Britain: Founder events and attempted genetic rescue in Scotland's beaver population.

Conservation translocations often inherently involve a risk of genetic diversity loss, and thus loss of adaptive potential, but this risk is rarely quantified or monitored through time. The reintroduction of beavers to Scotland, via the Scottish Beaver Trial in Knapdale, is an example of a translocation that took place in the absence of genetic data for the founder individuals and resulted in a small and suspected to be genetically depauperate population. In this study we use a high-density SNP panel to assess the genetic impact of that initial translocation and the effect of subsequent reinforcement translocations using animals from a different genetic source to the original founders. We demonstrate that the initial translocation did, indeed, lead to low genetic diversity (H o = 0.052) and high mean kinship (KING-robust = 0.159) in the Knapdale population compared to other beaver populations. We also show that the reinforcement translocations have succeeded in increasing genetic diversity (H o = 0.196) and reducing kinship (KING robust = 0.028) in Knapdale. As yet, there is no evidence of admixture between the two genetic lineages that are now present in Knapdale and such admixture is necessary to realise the full genetic benefits of the reinforcement and for genetic reinforcement and then rescue to occur; future genetic monitoring will be required to assess whether this has happened. We note that, should admixture occur, the Knapdale population will harbour combinations of genetic diversity not currently seen elsewhere in Eurasian beavers, posing important considerations for the future management of this population. We consider our results in the wider context of beaver conservation throughout Scotland and the rest of Britain, and advocate for more proactive genetic sampling of all founders to allow the full integration of genetic data into translocation planning in general.

The Cornwall Beaver Project: navigating the social-ecological complexity of rewilding as a nature-based solution

The story of the Cornwall Beaver Project is presented as the foundation of a review of the literature to consider the effects of beavers on geomorphological and hydrological processes, habitats, biodiversity, and people in agricultural landscapes in the UK. The review includes a comparison of the principles for rewilding as an approach to ecological restoration with IUCNs principles for Nature-based Solutions together with a summary of beaver reintroduction in Europe, and the impacts of beavers on hydrological and geomorphological processes, biodiversity and the human-wildlife conflict that arises from reintroduction. We note that rewilding principles require a paradigm shift in the relationship between humans and the rest of nature and a corresponding application of systems thinking to research, practice and policy. The combination of experiential and formal knowledge is assessed using a social-ecological systems framework to consider the potential of beavers to mitigate climate change impacts on agricultural landscapes in the UK and how rewilders might navigate the social complexity of beaver reintroduction to achieve large scale system transformation. We discuss the different lines of evidence about the impacts of beavers on landscapes as viewed through a system lens and conclude that: (1) beaver dams have considerable potential to store water but their ability to reduce flood risk is difficult to assess because of the complex interactions between the material available for dam construction, geomorphology, and the duration, extent and intensity of rainfall events; (2) beaver dams, especially when combined with buffer zones along water courses have considerable potential to enhance the resilience of agricultural landscapes and support a shift from intensive to agroecological farming; (3) scaling beaver reintroduction will evolve with the application of policies and practices that enhance the ability of land users to adapt and learn how to coexist with beavers. Our review proposes a low conflict strategy for rewilding with beavers that includes changes from a policy of conflict avoidance to a proactive policy to support practices that apply the tools of social-ecological systems science to the body of knowledge about the interactions between beavers and their environment.

Intermittent Prairie Streams in the Northern Great Plains: A Case of an Undervalued Ecosystem

Small (<15 m wide), intermittent prairie streams in western South Dakota, a semiarid part of the northern United States, are undervalued ecosystems because they do not exemplify the values of classic, flowing streams. However, they are valuable as wildlife corridors, aquatic habitat for drought-adapted species, and support of local grazing economies. We surveyed 90 streams in 2018–2019, collecting data on geomorphic, water chemistry, and biological properties, focusing on vegetation and grazing impacts. We developed an approach for categorizing streams by landscape position and flow regime to facilitate appropriate land management and stream restoration actions. The result was a published landowner guide to provide information on low-tech riparian management and restoration options of the four stream types we categorized. The headwaters streams and woody draws with drainage areas <26 km2 are the most abundant types and exemplify the issues described above. Large rivers, despite drainage areas exceeding 260 km2 can go dry. Management issues include invasive plant species, lack of woody riparian establishment, poor water quality, overgrazing, channel incision, and water stress from climate change. The most cost-effective management practices involve rotational grazing and practices that reduce cattle impacts. More recently, beaver dam analogs have been installed and beaver reintroduction is being considered along with reestablishment of native bison herds in place of cattle. Intermittent prairie streams present an excellent case study of an undervalued ecosystem, illustrating the challenges and opportunities of such systems. Engagement of grazing landowners can improve stewardship of these systems.

A tale of tails: the use of Eurasian beaver (Castor fiber) tails for ageing and individual identification

With increasing technology and knowledge, the range of methods used to monitor wildlife is growing. As many invasive techniques have been shown to negatively impact study populations, the use of non-invasive methods is increasing. With Eurasian beaver (Castor fiber) reintroductions occurring across much of Europe, monitoring of beavers is becoming increasingly important; however, some frequently used techniques are invasive. We therefore aimed to examine potentially non-invasive methods of identifying and ageing them from the tail. Tails from previously deceased beavers were photographed with a Nikon D3500 DSLR camera across 3 distances: ‘close’, ‘medium’ and ‘far’, and the pattern of the scales were examined by eye to determine accuracy of individual identification. Photographs including a grey standard were used to determine the accuracy of ageing beavers from the colour of the tail. The accuracy of individual identification was 100% across all distances; however, the results from ageing showed the method to be inaccurate. The success of the individual identification shows that this method could be effectively used as a non-invasive method for monitoring beaver populations, especially in captivity.

Aggregated mental models predict observed outcomes following Eurasian Beaver (Castor fiber) reintroduction

Outcome prediction is important for conservation; however, analysis may be hampered by specialist resource deficiencies. Mental modelling techniques offer a potential solution, drawing on accessible sources of knowledge held informally by local stakeholders. Mental models show linked social and ecological variables from the perspectives of community members, whose insights may otherwise be neglected. Currently, an important weakness in conservation mental modelling is inadequate attention paid to real-time model predictive validity. To address this knowledge gap, baseline mental model predictions concerning Beaver (Castor fiber) reintroduction in Southwest England were followed up at three years. Participants were invited to submit outcome observations for concept variables identified in their original models, blind to inferences based on model dynamic analysis, so that the two sets of data could be compared. Individual concept values and models were found to show weak and highly inconsistent predictive validity, however, multi-stakeholder aggregated mental models showed consistently strong predictive performance. This finding was enhanced by setting tighter thresholds for inclusion of individual model items in aggregation procedures. Threshold effects can be interpreted as a reflection of greater agreement: tighter thresholds retain more highly shared model components. It is proposed that enhanced real-time predictive validity for aggregated models is explained by a ‘wisdom of the crowd’ statistical effect, analogous to well-recognised crowd judgement effects observed in relation to much simpler questions. The findings show the scope for stakeholder mental modelling methods as an investigative tool, to supplement more conventional ecosystem assessments in predicting data-poor conservation outcomes.

The Influence of Eurasian Beaver (Castor fiber L.) Activity on the Transformation and Functioning of Riparian Phytocoenoses in the Southern Boreal Zone (European Russia)

The reintroduction of Eurasian beaver (Castor fiber L.) results in significant changes in ecosystems. The purpose of this study is to assess the impact of the environment-forming activity of C. fiber on the riparian phytocoenoses of the Raifa forest sector of the Volga-Kama State Nature Biosphere Reserve (Middle Volga region, European Russia) after the reintroduction. Phytoindication methods of ecological–coenotic groups and indicator values were used to assess changes in environmental conditions under the influence of beaver activity. The influence of the beaver reintroduction factor on the increase in the moisture regime (by three points according to the Tsyganov indicator values) and the illumination of habitats, the richness of soils in nitrogen, and the acidity and salt regime of soils (by one point) was revealed. Under the conditions of fodder and construction activities of the beaver, an increase in the proportion of aquatic and wetland groups from 10.2% to 28.2% and boreal plant species from 15.0% to 27.6% was detected. An expansive nature of the change in the degree of landscape occupancy with wetland plants was noted. A decrease in the degree of landscape occupancy (3 to 2 points) of the distribution of ruderal species in the riparian zones of the waterbodies of the reserve due to the activity of the beaver was revealed. Based on phytoindication and ecological–coenotic analyses, it was shown that the reintroduction of C. fiber into the waterbodies of the Raifa forest sector of the reserve is responsible for maintaining the necessary microclimatic conditions for the preservation of natural southern boreal communities. The results obtained can be used for predictive assessment of the influence of the beaver on riparian (small rivers and lakes) plant communities of forest ecosystems in the Middle Volga region of European Russia and other regions of the planet with similar environmental conditions.

Can reintroduction of beavers improve insect biodiversity?

Ecosystem engineering species, such as beavers, may help the restoration of biodiversity. Through the building of dams and lodges and altering the natural hydrology, beavers change the habitat structure and create multiple habitats that facilitate a wide variety of other organisms including terrestrial invertebrate communities. Here we study the effect of beaver reintroduction in Klosterheden in Denmark on biomass of flying invertebrates and diversity of moths. Further, aerial photos were used to assess riparian structure and productivity using the normalized difference vegetation index (NDVI). Our findings show that the presence of beavers affected flying invertebrate biomass, but that this was dependent on time of the year. Further, a strong effect of presence of beavers was found on diversity of moths. The results also show an increase in vegetation productivity and structural heterogeneity at sites with presence of beavers. Overall, our results demonstrate the importance of beavers as important ecosystem engineers that affect invertebrate species composition and abundance, as well as riparian structure and productivity.

Provisioning of breeding habitat by beaver and beaver dam analogue complexes within the Great Salt Lake catchment

Abstract Beaver are ecosystem engineers capable of converting free‐flowing lotic habitats into a series of lentic ponds, thereby enhancing the wetland area of a riverscape. Process‐based riverscape restoration using beaver reintroductions and mimicry (beaver dam analogues, BDAs) are increasingly used to restore functions, the provisioning of services, and improve the resiliency of ecosystems across North America and Europe. Beaver can create breeding habitat for a wide range of species within the highly imperilled class Amphibia by increasing wetland area, increasing emergent vegetation, prolonging wetland hydroperiod, and creating deep ponds. However, it remains unclear whether BDAs are creating suitable breeding habitat for amphibians by adequately emulating crucial ecosystem processes. We investigated the relationships between beaver dam and BDA complexes with amphibian breeding occupancy across four catchments feeding the Great Salt Lake, U.S.A. We surveyed 24 beaver dam complexes and nine BDA complexes during the 2019–2021 breeding seasons with varying levels of water availability. We compared environmental characteristics between beaver and BDA complexes, including elevation, depth, and fish relative abundance among others. We then used occupancy models to evaluate factors affecting breeding occupancy of the most frequently encountered amphibian species, barred tiger salamanders (Ambystoma mavortium). Without accounting for imperfect detection, at natural beaver ponds we recorded barred tiger salamanders in 58% of sites, boreal chorus frogs (Pseduarcris maculata) at 17% of sites, and northern leopard frogs (Lithobates pipens) at 4% of sites. Tiger salamanders were the only amphibian found at BDA sites, occupying 11% of those sites. We found that beaver complexes had 3 times less fish relative abundance, were 250m higher in elevation, 32 years older, and 0.43 m deeper than their BDA counterparts. Meanwhile, emergent vegetation height, water temperature, and hydroperiod demonstrated no significant differences between site types. BDAs modified ecosystem processes in a way that only partially replicated modifications by natural beaver dams. Occupancy models suggested that fish relative abundance, altitude, age, and being at the top of the drainage network were the most important variables for predicting tiger salamander breeding occupancy. Overall occupancy rate of tiger salamanders was 60%, while BDA complexes had a modelled occupancy rate of 14% compared to 78% in natural beaver complexes. Survey year did not appear to be an important factor in tiger salamander occupancy despite varying levels of water availability. Beaver and BDA complexes located near the top of their effective drainage or tributary junctions appeared to support amphibian along with fish species, thus boosting local diversity relative to a stream with only fish species. We therefore suggest future beaver restoration efforts target the top of effective drainages to benift both taxa. Overall, we found that while BDAs have the capacity to provide amphibian habitat, their younger age and higher fish abundance may explain why they are less effective than natural dams. Managers should therefore consider that the effects of restoration with BDAs may not be immediate, and future maintenance may be required.

A glimpse of the long view: Human attitudes to an established population of Eurasian beaver (castor fiber) in the lowlands of south-east England

IntroductionThe Eurasian beaver (Castor fiber) is a native species to Britain that after being absent for 400 years has been restored to the English countryside. The first beavers were released into a reserve in Kent in 2001/02, making this one of the first beaver release areas in the UK. This paper examines attitudes towards beaver presence in the landscape as well as public perception of beaver benefits and impacts with respect to the environment and human society.MethodsQualitative questionnaires were utilised to investigate factors influencing social attitudes and support for beaver reintroduction, as well as the relationship between sociodemographic variables and attitudes. Inhabitants of Kent and its immediate surroundings were surveyed during June and July of 2020 (n=407) with a focus on three interest groups – environmentalists, farmers and the general public.ResultsPerceptions included mostly beneficial impacts on nature and biodiversity, whereas less positive impacts were associated with economics, agriculture and fisheries. In general, local attitudes towards beavers were positive, mainly sustained by feelings of liking this wildlife species and valuing their presence. People´s attitudes positively influence willingness to support the reintroduction of beavers. Twenty years after their initial release, results indicate broad support for the beaver reintroduction in Kent and people´s tolerance of beavers. The majority of respondents were in favour of nonintrusive management techniques to mitigate beavers’ undesirable impacts.DiscussionThese findings suggest the need to develop an optimal management strategy that incorporates public views and gives advice on the best approach to manage this wildlife species. This research provides theoretical and practical underpinning for beaver management and conservation in Britain.

Impact assessment of Eurasian beaver reintroduction on riparian phytocenosis of the Raifa forest in Volga-Kama Nature Reserve

Statistically significant changes in microclimatic environmental factors under the influence of the activity of the European beaver in the territory of the Raifa section of the Volga-Kama Nature Reserve were revealed. The influence of the beaver reintroduction factor on the change in the moisture and illumination regimes of habitats, the richness of soils with nitrogen, the acidity and salt regime of soils has been established. In the conditions of fodder and construction activities of the beaver, an increase in the proportion of groups of aquatic, wetland and boreal plant species was noted, as well as the expansive nature of the change in their activity. There was a decrease in the activity of the distribution of ruderal species in the conditions of beaver activity. Based on phytoindication analysis, it has been shown that the reintroduction of the beaver into the water bodies of the Raifa section of the Volga-Kama Reserve is responsible for maintaining the necessary microclimatic conditions to preserve the natural boreal communities.

The Climate Science for Ecological Forecasting symposium

The Climate Science for Ecological Forecasting symposium

Monitoring, modelling and managing beaver (Castor fiber) populations in the River Otter catchment, Great Britain

Abstract Eurasian beaver (Castor fiber) were nearly hunted to extinction but have recovered to occupy much of their former range. Beaver were extirpated from Great Britain c. 400 years ago but have recently been reintroduced. The River Otter catchment, Devon was the site of the first licensed wild release of beavers in England. With further releases being considered, there is a need to better understand population dynamics of this native, keystone species to inform conservation and management. Field signs were surveyed from 2015 to 2021. A semi‐automated territory detection method was adopted to estimate territory counts. A spatially explicit model was developed to estimate the ecological territory capacity of the catchment. Future territory expansion was modelled using logistic growth curves; initial growth rate was estimated from observed territory counts and the estimated territory capacity range was used to define the limiting value of the growth curve. Beaver territory removal was simulated, across a range of management intensities and start times, to determine potential impacts of translocation or lethal control upon population dynamics. Territory numbers increased from four to 18, inclusive of four additionally released individuals, during study period. In the absence of population management, the territory capacity of the catchment was estimated to range between 120 and 183; this may be reached between 2028 and 2057. Simulated territory removal, where territories were removed at a fixed rate from the sum of the estimated total population and the population increase for that year, demonstrated large uncertainties in predicted population responses. Simulations with territory removals >3/year all predicted potential population collapse. This finding emphasizes the need for caution when considering population management strategies; translocation of animals out of the catchment or culling should be considered only when populations are established and all alternatives have been considered. These results provide critical information for the expected rate and magnitude of beaver population change in the River Otter catchment. The methods provide a reproducible and generalizable approach for understanding beaver population change, which can inform policy on the reintroduction of beavers and the potential timing and intensity of future beaver population management.

Impact of fine-grained sediment on mountain stream macroinvertebrate communities: Forestry activities and beaver-induced sediment management

Fine-grained sediments are a natural component of river systems. Human activities generate additional sources of fine sediment. In mountainous areas, the anthropogenic inputs of fine sediments are associated with forestry. The aim of this study was to analyse the differences in the macroinvertebrate communities between the reference and caused by forest harvesting activities increased influx of fine-sediment to mountain streams. The tested hypothesis was that the macroinvertebrate communities will differ depending on the intensity of forest harvesting practices in the stream catchment that causes excessive influx of fine sediment into the stream. The reintroduction of beavers in the study area, and the formation of in-stream beaver dams, contribute the accumulation of sediments in stream sections with slower water. Thus, it was also assumed that by capturing and storing fine sediments, may contribute to the restoration of the natural structure of the benthic communities downstream of the ponds. The study was carried out in a mountain stream catchment area (Carpathians, Poland), in which inflow of fine sediments in the stream sections varied in intensity. The study was conducted over three years (2018–2020). The extensive use of forest roads, timber skidding trails, and timber storage areas produced fine sediments that clogged the interstitial spaces between the stones in the riffles, limiting the presence of rheophilic taxa associated with coarse-grained substrates. The reduction of the number of scrapers and shredders (i.e. primary consumers) associated with the influx of fine sediments may significantly affect the entire food-web structure in stream ecosystems. The capture and deposition of fine sediments in beaver ponds may accelerate the revitalisation of the flowing sections of the stream. Beaver-induced sediment management is strongly recommended as a beneficial practice that could contribute to ecological preservation and the potential of streams, particularly in mountain areas.

Where the wild beavers are: Climate and landscape controls on beaver pond area in snow‐dominated rangeland headwaters

AbstractBeavers are of increasing interest as a mechanism for ecosystem restoration. However, the physical watershed characteristics that allow for successful beaver re‐establishment are not consistent across habitat suitability models. We delineated the extent of beaver impounded surface water in the Pole Mountain Area (PMA) of south‐eastern Wyoming with six National Agricultural Imagery Program acquisitions over an 18‐year time period via a random forest classification algorithm. We computed beaver pond area for first‐ and second‐order watersheds within the PMA and related the impounded pond area to climatic metrics such as maximum annual snow water equivalent and snowmelt and rain input into the ground. There was no apparent relationship between annual climate metrics and beaver pond area. Further, we developed a random forest regression model to correlate beaver pond area with topographically derived watershed characteristics (e.g. hillslope size and riparian area size) to explore physical controls on impounded area at the watershed scale. Controls differed for first‐ and second‐order watersheds, with pond area in smaller watersheds largely being controlled by lateral water contributions from the hillslopes and in the larger watersheds by water from upstream and available space in the riparian areas. Interestingly, vegetation height did not emerge as an important predictor for pond area, likely because of generally good availability of forage material in all watersheds. This study improves our understanding of watershed characteristics that contribute to beaver habitat suitability and can be used to guide beaver reintroduction efforts through analysis targeted at identifying watersheds most appropriate to beaver pond construction.

Emotionally augmented mental models, connectivity and beaver reintroduction in Southwest England

Understanding the psychology of human-wildlife interactions has grown beyond cognitive frameworks to include appreciation of roles played by emotion in human responses to wildlife. From its beginnings as an essentially cognitively framed proposition, mental modeling has been shown readily applicable to representing and interpreting stakeholder perspectives on combined social and natural systems, but lacks an integrated approach to emotion. This is an important knowledge gap. To commence an investigation into the relationship focused on the requirements of wildlife conservation, we carried out a case study of perspectives toward a free-living Eurasian beaver (<em>Castor fiber</em>) reintroduction in Southwest England, ecologically significant as a generator of high-value wetland habitat while interacting strongly with local human interests. Using fuzzy cognitive mapping techniques, we report predictive relationships between model measurements and subjective emotional valence elicited in relation to stakeholder conceptual content. Significant interactions were identified between three measures of concept connective influence within mental models and associated emotional valence intensity: single model concept connective salience, aggregated model concept connective salience, and aggregated model predictive inferences made by dynamic analysis. A possible explanation for these findings is outlined in which we propose that criteria-based evaluations suggested by appraisal theory of emotion are sensitive to the strength and distribution of connective influences within mental models. Apart from its theoretical significance, the evidence presented in this paper highlights the importance of attending to conservation stakeholder emotional experiences, and may assist in new approaches to mitigation where conservation objectives require human adjustment.

Renewed coexistence: learning from steering group stakeholders on a beaver reintroduction project in England

Species reintroductions are growing in popularity, and example motivations include supporting species populations or the restoration of ecosystem function. Interactions between humans and the reintroduced species are likely to occur post-reintroduction. Coexistence between humans and wildlife is adaptive and dynamic, in part requiring management of conflicts between humans and wildlife, or of conflicts between humans over wildlife management. We seek to learn from the experiences of steering group members in a Eurasian beaver (Castor fiber) project in England and identify how governance of coexistence with reintroduced species may differ from the governance of coexistence with species that are already present in the landscape. Using a qualitative thematic analysis of an online survey, we identify a series of lessons in six key areas: (1) project governance, (2) stakeholder engagement, (3) research and monitoring programme, (4) strategy to manage arising conflicts, (5) public engagement, and (6) broad perspectives on reintroduction trials. We advocate for reflective evaluation as an essential component of reintroduction projects to enable knowledge-sharing from experiences, leading to improved practices in the future. Reflecting on our analysis, we identify and define ‘Renewed Coexistence’—a new term that draws on pre-existing coexistence knowledge but identifies the unique elements that relate to governing coexistence with reintroduced species.

The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification

Globally, freshwaters are the most degraded and threatened of all ecosystems. In northern temperate regions, beaver (Castor spp.) reintroductions are increasingly used as a low-cost and self-sustaining means to restore river corridors. River modifications by beavers can increase availability of suitable habitat for fish, including salmonids. This study investigated the response of a population of brown trout (Salmo trutta) to reintroduced Eurasian beaver (Castor fiber) habitat modifications in northern Scotland. The field site comprised two streams entering a common loch; one modified by beavers, the other unaltered. Electrofishing and PIT telemetry surveys indicated abundance of post-young-of-the-year (post-YOY) trout was higher in the modified stream. Considering juvenile year groups (YOY and post-YOY) combined, abundance and density varied with year and season. In the modified stream, fork length and mass were greater, there was a greater variety of age classes, and mean growth was positive during all seasons. Beavers had profound effects on the local brown trout population that promoted higher abundances of larger size classes. This study provides important insight into the possible future effect of beavers on freshwater ecosystems.

Stakeholder mental model analysis supports focused conservation policy and actions for Eurasian beaver (Castor fiber) reintroduction

Eurasian beaver, Castor fiber has been restored to England’s natural fauna following a trial reintroduction located in the country’s southwestern region. Beavers characteristically generate profound and frequently beneficial shifts to river dynamics, nutrient cycling, biodiversity, and human cultural experience, but can also be associated with unwanted human interactions, impacts and costs. Consequently, an important objective of the trial design was to ensure conservation leadership, monitoring and mitigation for problems such as burrowing, damming and flooding, and damage to valued trees. To understand how these developments are perceived and accepted, implicated key stakeholder mental models were elicited and explored, using fuzzy cognitive map techniques. Analysis showed broad alignment of ecological understanding between stakeholders. Social perspectives showed marked divergence, a focus of concern as social conflict can undermine otherwise ecologically viable conservation benefits. To investigate perceived effectiveness of trial conservation measures, stakeholder models with and without conservation actions were experimentally compared under dynamic analysis. Overall, the findings indicate that actions taken are sustaining beaver acceptance and limiting persecution. Of stakeholder groups examined, farming appeared most susceptible to model divergence, but also strongly protected by mitigation. This is important as reconciling mental model differences is considered a necessary element in building socio-ecological system resilience. These findings highlight mental model analysis as a valuable aid to assessment of social dimensions of conservation policies. Further, mental modelling could help to focus how farm payment reform in the U.K. and similar economies might be used to support leadership and mitigation designed to improve human-beaver ecosystem resilience.

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

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. 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). 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. 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.