6. Assessment of Alternatives
The BiS report set out 4 potential policy scenarios for beavers in Scotland, ranging from the full removal of beavers to the widespread reintroduction of beavers. The scenarios were broad and a number of sub-options were possible. The benefits and risks were outlined for all scenarios.
6.1 Alternative scenarios
As detailed in the scoping report, the preferred policy alternative draws from both scenarios 2 and 3.
This is also based on the understanding that any scenarios which proposed future beaver presence would also require population reinforcement.
The 4 policy alternatives considered are:
- Scenario 1 - full removal of beavers from the wild in Scotland
- Scenario 2 - restricted range. Allowing beavers to expand from their current range, but specific catchments would be managed to keep them free from beavers.
- Scenario 3 - widespread recolonisation. The beaver population would be allowed to expand to its natural limits. Eventually this could include further releases outside the two current population areas.
- Scenario 4 - accelerated widespread recolonisation. Proposals for new releases could be considered immediately.
The key benefits and risks of each scenario are provided in the table below.
Comparison of benefits and risks of alternative policy scenarios
Table 6.1 Comparison of the benefits and risks of alternative policy scenarios
1. Full Removal
Scenario 2 - restricted range
Scenario 3 - widespread recolonisation
Scenario 4 - accelerated widespread recolonisation
6.1.1 Scenario 1 - Full removal
Beavers would be fully removed from the wild in Scotland.
It should be possible to remove the vast majority of beavers from the wild in Scotland within five years. However, this will be dependent on the scale of resources available. There would need to be a certain level of surveillance and reactive management to deal with any remaining individuals, further escapes from captive collections and illegal releases.
Implications for beavers
This would involve the killing and/or capture of all beavers from Knapdale (likely to be over 10 animals) and the Tay and Earn river catchments (where there may be 150-200 animals). Some may be rehoused in private collections, but given the numbers involved it is likely that most would have to be humanely destroyed.
There may also be longer term inconsistency and implications if England decided to reintroduce beavers more widely in the future and animals start to colonise the Scottish Borders and Dumfries and Galloway. These animals would then need to be removed, probably on a continuous basis. At present, beaver reintroduction has been proposed in Wales and beavers are being tolerated and monitored at the River Otter in south-west England for a trial period.
Effects on the environment
Removal would avoid the need to put in place management to protect certain vulnerable species and habitats from detrimental impacts.
However, there would be an overall loss of potential future biodiversity benefits and wider positive ecosystem services. The overall detrimental impact on long-term ecological goals to halt biodiversity loss, including contributions to meeting Aichi 2020 targets on biodiversity, would be hindered.
It can be assumed that the Tayside beaver population has grown since the last Tay beaver survey in 2012, which estimated 38 or 39 beaver colonies (approximately 106-187 animals). The TBSG final report noted that there were 11 reports of beaver activity between 2013 and 2014 in areas not identified in the 2012 survey. Population growth rates have been measured at anywhere between 5% and 34% per year in other studies. The recent modelling study estimated 46 colonies (198 beavers) present in 2016.
One study has estimated the time required to clear a beaver colony as being three days using two people and a combination of trapping and shooting techniques, although this is based on methods that would be illegal under Scots law ( Chapter 5). If these figures are applied to Tayside, then approximately 280 person-days would be required to clear the estimated number of colonies if the locations are known. However, it would take longer to remove the animals because of the types of techniques that would be legal and appropriate for Scotland.
Once the main recorded colonies have been removed, it becomes more difficult to estimate the medium to longer term resources required for this scenario. There would be diminishing returns as the beaver density is reduced, since finding individuals from a low-density, dispersed population would be a difficult task. Significant time would be needed to deal with any new reports of activity or sightings and to monitor the Tay, Earn and surrounding catchments to confirm eradication.
The 2012 Tay survey involved identifying previously reported areas of beaver activity and suitable beaver habitat to target the fieldwork. Similar techniques could be used for any beaver removal operation, for example by applying the types of mapping and predictive modelling outputs described in section 3.2, combined with more recent field records and preliminary survey work.
Resources would also be required to remove several beaver families from Knapdale. Although a detailed assessment would be required to calculate the likely costs of removal, a rough estimate, taking the above into account, could be around 1,000 person-days needed to complete the main initial task, with further time required for follow-up surveillance. For example, any beaver originating from an unauthorised release presents increased risks associated with unknown provenance, including those relating to public health. This can be compared to the complex and ambitious Hebridean Mink Project which started in 2001 and costs about £350,000 per year. Mink are more difficult to locate than beavers, and the original numbers of mink were far higher, but statistical models have predicted that the project will have successfully extirpated American mink from Lewis and Harris between 2014 and 2021.
It is anticipated that many land managers would be willing to collaborate with any removal of beavers. Working with land managers through a voluntary approach is always the preferred option, although legal powers now exist to compel people to take action when necessary.
A trial reintroduction of beavers to Wales has been proposed and the English wild beaver population on the River Otter will be tolerated until 2020. There are reports of beavers living in the wild in other parts of England, although to date these have been in the south. In the long term it is possible that other populations may become established in England or Wales, arising from authorised or unauthorised releases, and ultimately beavers may start to colonise Scotland. Under scenario 1, beavers would be culled if they colonised Scotland, with the possibility of ongoing and long-term management and associated costs. Removal will be contentious and will be opposed by a range of individuals and organisations. There is the possibility of interference with any trapping or culling operations.
This scenario has similarities to the approach used for some non-native species, such as American mink.
There would be short-term costs of eradication and longer term costs of monitoring within Scotland and preventing colonisation from any potential populations south of the border. Resources already invested in the SBT and other Scottish initiatives may be perceived as wasted by some parties. These can be compared with the costs and benefits associated with allowing beavers to remain.
6.1.2 Scenario 2 - Restricted range
Beavers would be allowed to expand from their current range, but specific catchments would be managed to keep them free from beavers.
Although it is difficult to predict, population models suggest that beavers may not expand far from their current catchments over the next two or three decades ( section 3.2), assuming there is no human assistance. However, as the density of the populations increase over time, there is an increased likelihood of dispersal into neighbouring catchments.
Implications for beavers
There would be no further releases of beavers other than for population reinforcement, for genetic reasons and/or to increase the numbers of animals. Beaver range expansion would probably be slow from the current populations (see section 3.2) with population models suggesting no or limited natural expansion outside the Tay and Earn catchments over the next 30 years. Range expansion at the national scale would therefore take longer in comparison with scenarios 3 and 4.
Although the Knapdale population is currently stable, there are inherent risks to it if reinforcement is delayed. It was not designed as a founder population for a reintroduction, and there is a risk that it will become extinct in the short term ( section 3.2). There may also be a risk of inbreeding on Tayside in the future, and so further monitoring of genetic health would be needed to decide if reinforcement is required.
If numerous catchments were 'designated' as beaver free, beavers could be restricted to a series of isolated ranges, and there is a risk that the overall population would require regular reinforcement to combat genetic drift.
Effects on the environment
Some of the potential benefits of reintroduction would be retained, although over a relatively small area, particularly in the short to medium term. There would be some future biodiversity benefits, and wider positive ecosystem services, including a limited contribution to meeting Aichi 2020 targets on biodiversity. The status quo would be maintained within beaver-free catchments.
Beavers would have positive and negative impacts on a wide range of environmental and socio-economic interests where they occur. Within the areas where beavers are currently present, or may be colonised, appropriate monitoring and management would be needed. For example, the monitoring of potentially vulnerable species and habitats would be required and robust beaver management required in specific areas. Further research may also be needed (e.g. examining potential impacts on biological or socio-economic factors) and appropriate levels of targeted deer management may be required to avoid potential negative, and promote positive, ecological effects (see section 3.4.1).
Within the catchments concerned there would be an opportunity to develop a programme of riparian habitat restoration and creation targeted in beaver areas, and areas which may be colonised ('buffer zones', see Chapter 5), which would help to promote the positive effects of beavers, benefit land managers and users, reduce conflict and benefit vulnerable species.
The management strategy developed for this scenario would include detailed guidance on the practical and legal issues surrounding beaver management. Standard beaver management techniques, outlined in Chapter 5, would be employed in the colonised area. The costs of management would increase as the beaver population increased in size and range. There is predicted to be a relatively high level of connectivity between catchments for beavers (see section 3.2). Therefore, over the long term and once populations within catchments are established, beavers are unlikely to be significantly restricted from colonising other catchments by the natural features of the landscape. However, beaver colonisation from the two current beaver areas is expected to be slow in the short to medium term.
Keeping an entire catchment beaver free would be labour intensive. The difficulties would be highly dependent on the nature of the catchment, the potential barriers to dispersal to adjacent catchments and surrounding beaver populations. For example, large catchments, with large borders, adjacent to high-density beaver populations, may require high levels of monitoring and management to keep them beaver free into the long term.
An option that might be applied within this scenario would be 'designating' specific beaver-free areas within an individual catchment, based on factors such as sensitive land use. This approach would require intensive management over the long term. Non-lethal options, such as the creation of 'buffer zones' in other areas (see Chapter 5), may have a role, but it would also require the culling or trapping of potentially high numbers of dispersing beavers on an annual basis. A Norwegian study highlighted that: '…the spread of beavers within a river system cannot, in practice, be contained without a heavy, and constant, directed hunting or trapping effort'. Any future management strategy would need to examine the feasibility, practicality and resourcing of such an approach.
Certain types of management, such as culling or trapping, would be more likely to be required in the longer term and would be more contentious. Keeping areas free of beavers may go against the wishes of some land managers, as well other individuals and organisations.
There is a risk that some may view this as too slow an approach and unauthorised releases may become more prevalent. Appropriate management and legal action would then be needed.
This scenario has similarities to the approach used to manage the spread of some non-native species, such as sika deer Cervus nippon.
Although there are uncertainties, it seems likely that, overall, the ongoing costs of keeping a catchment (or part of a catchment) beaver free could be significant.
6.1.3 Scenario 3 - Widespread recolonisation
The beaver population would be allowed to expand to its natural limits. Eventually this could include further releases outside the two current population areas. However, initially the focus of resources would remain with Tayside and Knapdale and in developing an appropriate management strategy. This would be a more cautious approach than in scenario 4.
Although it is difficult to predict, population models suggest that beavers may not expand far from their current catchments over the next two or three decades ( section 3.2) without human assistance. As the density of the populations grew over time, there would be an increased pressure upon young animals to disperse into neighbouring catchments to find unoccupied suitable territories. Conversely, if further releases took place in new catchments with large areas of available suitable beaver habitat, then populations may not expand substantially beyond those catchments for two or three decades. At a national level, the range of beavers and size of the population will depend on the number and timeframe of further releases.
This scenario envisages a cautious approach to further releases over the short term (e.g. the next five years or so), allowing time to develop a detailed management strategy and for resources to be focused on ensuring that viable, appropriately managed populations are established at Tayside and Knapdale.
Implications for beavers
The Knapdale beaver population borders the River Add and a series of small coastal catchments. These are the areas that would be expected to be colonised first after population reinforcement. In the longer term the population is likely to expand into Loch Awe and across much of Argyll.
The 2012 River Tay beaver survey located animals in the Tay, Earn and Forth river catchments. These catchments border the Dee, South Esk, Lunan, Monikie, Dighty, Dundee Coastal, Annaty, Farg, Loch Leven, Devon, Allan, Bannock, Carron, Lomond, Awe, Etive, Blackwater, Lochy and Spey catchments, which would be expected to be colonised first ( section 3.2 highlights the predicted high connectivity between catchments). Therefore, the Tay population has the potential to colonise much of Scotland in the longer term. In particular, the Spey catchment to the north and the Loch Lomond catchment to the south-west, have large areas of suitable beaver habitat.
It is expected that beavers will need to be present within an area for 25 years before population growth plateaus and beavers may be considered to be at high density. A key conclusion of the recent population modelling work was that beaver range expansion will be slow. For example, beavers are unlikely to significantly expand from their current catchments within the next two or three decades.
Therefore, there is an argument for further releases in due course. The size of the founder populations and the suitability of release sites will be the key determinants of the success of beaver reintroduction, as for any species reintroduction. The Best Practice Guidelines for Conservation Translocations in Scotland sets out key considerations. This scenario provides time to develop a more strategic approach to planning a national reintroduction that addresses these issues, and therefore a better chance of establishing a viable, long-term beaver population.
For example, enabling the two current populations to link up may provide improved population stability. Further releases within the Awe catchment may be the simplest approach to linking the populations, as it borders the Tay catchment, and lies just 8 km from the Knapdale population.
Other prioritised areas could be identified for further releases based on the abundance of potential core beaver habitat within a catchment. The Ness, Spey, Tay and Lomond river catchments were previously identified as major areas of potential beaver habitat within Scotland. More recent analyses have supported this assessment ( section 3.2), although other areas would also be suitable.
Effects on the environment
The current benefits of the Knapdale and Tayside beavers to biodiversity and wider positive ecosystem services would be retained. In addition, the wider reintroduction of beavers would represent a clear commitment to creating longer term biodiversity benefits.
The speed of colonisation in this scenario would depend on the timing and extent of further releases. A slow speed of colonisation would mean widespread positive ecological effects might not be felt for some years and beaver presence would play a limited role in contributing to Scotland's Aichi 2020 targets. However, a slower colonisation may also provide more time to plan and prepare for appropriate management. Further beaver releases could be targeted to help restore degraded ecosystems.
Beavers would have an impact on a wide range of environmental and socio-economic factors where they occur. Within the areas where beavers are currently present, and are likely to be colonised, appropriate monitoring and management would need to be in place. For example, the monitoring of potentially vulnerable species and habitats would be required, and robust beaver management in specific areas. Further research may be also be needed (e.g. examining potential impacts on biological or socio-economic factors), and appropriate levels of targeted deer management may be required to avoid potential negative, and promote positive, ecological effects. A programme of riparian habitat restoration and creation targeted in beaver areas, future release sites, and areas which may be colonised ('buffer zones'), would help to promote the positive effects of beavers, reduce conflict, benefit land managers and users, and benefit vulnerable species.
In this scenario further releases of beavers would be considered, although releases at sites outside Knapdale and Tayside would not be encouraged for a number of years. Short-term effort could concentrate on improving the viability of the Knapdale and/or Tayside populations.
The management strategy developed under this scenario would include detailed guidance made available on the practical and legal issues surrounding beaver management. This would be developed over the next few years with key stakeholders, and would include a strategic approach to identifying where further releases might be most appropriate.
The types of standard beaver management techniques outlined in Chapter 5 would be employed in areas with beavers. In the longer term the costs of management would increase as the beaver population increases in size and range. There are no significant predators of beavers in Scotland, and populations may become large and/or high density in places. Management would be required to reduce potential negative impacts (much like deer management currently). Certain types of management that are more likely to be required in the longer term, such as culling or trapping, will be more contentious.
All further releases would need to address the Scottish Code for Conservation Translocations. The merit of further releases would be assessed against a range of criteria including local public support, ecological impacts, impacts on the status of the wider beaver population and an assessment of how quickly they may colonise an area without a release. There is a possible risk that some may view this as too slow an approach, and unauthorised releases may become more prevalent.
The option of 'designating' specific beaver-free areas within an individual catchment, described in scenario 2, could be considered for scenario 3 as well.
This is similar to the approach taken in Denmark. There, 18 beavers were released at a single site at Kosterheden in 1999 and impacts were monitored. The population had increased to approximately 165 individuals by 2011. Animals were then released at a second release site, at Arresø, in 2009. In the long term the Danish population is expected to be reinforced through the natural migration of beavers from Germany.
6.1.4 Scenario 4 - Accelerated widespread recolonisation
The beaver population would be allowed to expand to its natural limits. Proposals for new releases could be considered immediately. This would be a less cautious approach than scenario 3, and more reactive to new release proposals.
Many of the timescale issues set out for scenario 3 also apply to scenario 4. However, it is anticipated that releases at sites other than Knapdale and Tayside would happen sooner under this scenario, probably within the next few years. This would be subject to organisations coming forward with appropriate project proposals and resources.
Implications for beavers
Many of the implications for beavers set out for scenario 3 also apply to scenario 4. However, under this scenario releases at new sites may happen over the next few years, and therefore beavers will become re-established over wider areas within a quicker timeframe. However, there are risks that resources may be diverted from ensuring that the current populations at Knapdale and Tayside are viable. There may also be a lost opportunity in planning for the next phase of beaver releases at a national level, and ensuring the best chance of establishing a viable, long-term beaver population with wider benefits.
Effects on the environment
Many of the effects on the environment set out for scenario 3 also apply to scenario 4. Since there is the possibility of more beaver release sites over the next few years under this scenario, then that would mean any benefits to biodiversity and ecosystem services could be distributed more widely more quickly. The potential disadvantage is that there would not be the opportunity to plan the next phase of further releases in a way that may target and maximise these benefits most effectively and efficiently.
Many of the management implications set out for scenario 3 also apply to scenario 4. However, new beaver release sites may be approved before a management strategy has been finalised. There may be a risk that land use organisations, and some specialist conservation groups, feel beaver reintroduction is being rushed before some of their concerns are being adequately addressed. Other stakeholders may welcome such an approach, and there may be less risk of unauthorised releases taking place.
The option of 'designating' specific beaver-free areas within an individual catchment, described in scenario 2, could be considered for scenario 4 as well.
This approach has some parallels with other beaver reintroductions. In Switzerland there were uncoordinated releases of beavers at 33 sites over a 22-year period, and this lack of strategic approach to reintroduction was judged to be a major reason why there were initial problems with the viability of the population.
The policy agreed by Scottish Ministers draws from both scenarios 2 and 3 in the report. That is:
- Beaver populations in Argyll and Tayside can remain;
- The species will receive legal protection, in accordance with the EU Habitats Directive;
- Beavers will be allowed to expand their range naturally;
- Beavers should be actively managed to minimise adverse impacts on farmers and other land owners;
- It will remain an offence for beavers to be released without a licence, punishable by up to 2 years imprisonment and an unlimited fine.
The decision acknowledges the range of benefits of beavers being present in Scotland but also the importance of demonstrating how the re-introduction can best be actively managed to minimise adverse impacts on land managers in Tayside and Argyll before considering further reintroductions elsewhere in Scotland.
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