Published: August 2021
This report provides an update on beaver management in 2020; principally in the Forth and Tay catchments, informed by surveys conducted in 2012, 2017/18 and most recently 2020/21.
Beaver population and range
A survey of beavers on the Forth and Tay catchments was commissioned over the winter 2020/21 to provide an update on the current population and range.
- The survey found the number of active territories had more than doubled from that found in 2017/18 with evidence of 251 active territories compared with 114 in 2017/18 and 38/39 in 2012.
- Population expansion is most notable to the west (Tyndrum) and south, where expansion in the Forth catchment continues. Further expansion into the upper Forth and the Loch Lomond and Trossachs National Park is likely in the near term. No expansion was noted north of Pitlochry or east of Forfar.
- Overall the population has expanded annually by between 17% and 30%, with the upper estimate considered more likely. This is a greater rate of increase than between 2012 and 2017/18 (8-24%) suggesting that the population is in a phase of rapid expansion.
- Newly established territories were evident in all areas and outnumbered locations where territories had been abandoned. Evidence of abandonment was found in a minority of locations across all areas.
The Scottish Beaver Mitigation Scheme is continuing to support land managers experiencing negative beaver impacts through providing free advice and support for practical management directly by NatureScot staff or via external specialist advisors.
- The number of active mitigation projects is now 68.
- Due to Covid restrictions, site visits and the work of the technical sub groups slowed in 2020 but we carried out 94 site visits, largely in the latter part of the year.
- The operating budget for the mitigation scheme in the financial year 20210/21 was £91K, however, due to COVID related delays in some projects, the actual spend was approximately £40K.
A wider range of environmental measures are being explored through the Scottish Beaver Forum Technical Sub-groups with a view to developing field trails in situations that currently lack suitable mitigation approaches.
Species licensing can permit further interventions where mitigation solutions are not available or do not remove the risk of beaver impacts causing serious damage. This includes the removal of beaver dams, trapping and lethal control.
- Seventeen new beaver licences were issued in 2020 in addition to the 45 issued in 2019; with a notable shift in the types of licences from those solely intended to prevent serious damage to agriculture (growing crops) to include five licences on public safety grounds (damage to infrastructure) and one forestry; five licences related to mitigation projects.
- The geographic spread of licences reflects the increased range of beavers, however, the focus of lethal control licences (for which there were six new licences in 2020) remains in areas of Prime Agricultural Land in the Isla, Tay and Earn sub-catchments.
- In 2020 licence returns show that one third of licences were not used; 16 licences reported only having removed dams, six removed dams and carried out lethal control and 13 only carried out lethal control.
- Fifty six dams were removed under 22 licences and 115 beavers were killed under 19 licences (all on Prime Agricultural Land or in the case of one licence, on land assessed as having the properties of PAL).
- No lethal control was reported in the Kit Dependency Period (KDP, 1 April to 16 August) with most control taking place in the autumn when beaver signs become more evident.
- Thirty one beavers were trapped and moved to licensed enclosure projects in England following efforts to encourage licence holders to work with an experienced beaver ecologist to explore trapping in place of lethal control.
We have assessed the impact of licensed removals (both lethal control and trapping) in 2019 and 2020 on the conservation status of the species and have concluded that it continues to improve. The Beaver Management Framework, whilst still in its early years and continuing to be adapted is considered to be providing the necessary tools to enable land managers to address serious land use conflicts via a combination of mitigation and species licensing whilst allowing the natural range and population to continue to expand.
A Beaver Management Framework was put in place through consultation with the Scottish Beaver Forum membership prior to beavers becoming EPS on 1st May 2019. The Beaver Management Framework aims to balance the desire to allow the beaver population to continue to expand their range naturally whilst allowing significant detrimental impacts of beavers on particular interests to be managed. This framework includes the Scottish Beaver Mitigation Scheme, the species licensing regime, the policy on translocations, the research and monitoring strategy and further work to increase our understanding of the benefits or ecosystem services provided by beavers. NatureScot produced a report on the first year of beaver licensing in May 2020. This report aims to provide a similar overview of beaver management undertaken in 2020, principally in the Forth and Tay catchments and aims to set this in the context of information gathered over the winter 2020/21 on the current populations in the Forth and Tay catchments.
This report does not make recommendations for any changes to the Framework, which we would expect would be developed in discussion with the Scottish Beaver Forum and Scottish Government.
2. Update on the beaver population status from the 2020 winter survey
NatureScot commissioned a full survey of the beaver population around Tayside and other areas where there was evidence that beavers had recently colonised. This took place between October 2020 and March 2021. Survey methods matched previous surveys though previous surveys were largely conducted during summer. For full details see the survey report (Campbell-Palmer et al. 2021a).
2.1 Range and future expansion
The findings indicate that the current beaver natural range of the Tayside population has expanded most significantly to the west and south with territories now found as far west as Tyndrum, evidence of beavers around Loch Lomond (though no territories were found); with a continuing increase in territories in parts of the Forth catchment. Further expansion in the Forth and into the Loch Lomond and Trossachs National park is expected. Whether beavers will expand from Tyndrum into the Loch Awe catchment remains to be seen as headwaters can be significant barriers. The expansion of the beavers into the Forth catchment may have been across the headwater at Lochearnhead, given that headwater appears to be a less significant barrier and there is a beaver territory currently at the headwater.
Range expansion has not happened to the north and east with no evidence of beavers colonising the South Esk in the east nor moving past the Tummel dam at Pitlochry. Expansion into Fife has also been very limited. Some expansion has been noted along the north bank of the Firth of Tay into Dundee and the Firth may be a route of future expansion east. However, dispersal in salt water can be difficult for beavers.
2.2 Number of active territories
The contractors used the distribution of beaver signs to delineate beaver territories, with a combination of automated classification and expert judgment applied. The automatic classification was re-run on the data from the previous surveys to enable an objective comparison. Using only the automated classification, the number of active beaver territories increases from 85 in 2012 to 123 in 2017/18 and 196 in 2020/21. That represents an annual increase of 8% between the first and second survey and 17% between the second and third survey. However, the report authors judge that the results from the combined automated system and expert judgement are more representative and hence these figures are used in the analysis in the rest of this report (4.7).
Using the combined automated and expert classification on the 2020-2021 data and comparing with the numbers reported from the previous surveys (Campbell et al. 2013; Campbell-Palmer et al. 2018), the number of active beaver territories increases from 39 in 2012 to 114 in 2017/18 and 251 in 2020/21. That represents an annual increase of 24% between the first and second survey and 30% between the second and third survey, the accelerating rate of growth suggesting the population is in a rapid expansion phase.
Numbers of territories are the preferred measure of beaver population size as estimates of the number of beavers are derived from these figures using a multiplier of the average group size (around which there is variation). Hence the number of territories is the more reliable measure. However, our analysis also includes reference to the estimates of numbers of beavers derived from these figures as this allows a comparison with the number of beavers removed from the population (see 4.7). The 2020/21 figure roughly equates to 954 individuals (range 602 to 1381).
2.3 Evidence of impacts of control
Beavers were given protected status around midway between the 2017-2018 survey and the most recent survey. Losses of territories could result from natural changes (e.g. abandonment of an area due to resource depletion), control prior to protection or control and trapping under licence following protection. The latter is assessed in detail in section 4.7.
The recent survey noted, as expected given the increase in territory numbers, most areas showed a continuity of beaver activity or new activity. There were a minority of locations that had been abandoned by beavers, from either natural processes or licensed removal. These were scattered throughout the surveyed areas including the Tay, Earn, Isla and Forth sub-catchments. There was no evidence of losses over significant areas or contiguous territories.
3. Beaver Mitigation Scheme
3.1 Update on the Scottish Beaver Mitigation Scheme
The Scottish Beaver Mitigation Scheme is part of the Beaver Management Framework put in place when beavers became protected species. NatureScot must consider mitigation approaches to satisfy itself that there are no satisfactory alternatives prior to issuing licences.
Reflecting that beavers are still relatively newly returned to Scotland, NatureScot provides a range of guidance and support to land managers experiencing negative impacts from beavers in the form of advice and practical help with mitigation works. The scheme seeks to minimise conflicts and the need for licenced intervention. The scheme has continued in the last year, working directly with land managers and with Local Authorities, Network Rail and SUSTRANS on mitigation projects that they have implemented directly.
Since September 2020 (the earlier part of the year was affected by COVID restrictions when site visits were halted for some months) we have started to record types of cases and hence the numbers listed are for the period since that date and the preparation of this report.
Some enquiries can be resolved by the NatureScot Beaver Team providing advice over the phone (9 cases recorded), but many cases require a follow up site visit either from the team or our call off contractor (94 recorded). There are now 68 mitigation projects recorded on our scheme tracker that have received at least one visit and where works have been carried out or are proposed. Many of them will have been visited several times as projects are scoped and implemented. This compares with over a hundred queries in the first year of operation of the scheme.
NatureScot have published detailed guidance on how to protect individual trees from beaver impacts using weld mesh. To give an idea of costs; a 25m roll of weld mesh costing c. £90 inc VAT should be sufficient to protect 10 trees of 50cm diameter. One person can protect 5-6 trees per hour. Labour costs would vary depending on how this is delivered, which could be land managers directly, NatureScot staff or call off contractors. In the case of householders or public land we are exploring the option of involving NatureScot volunteers in this work. We have also produce a ‘how to video guide’ to tree protection with mesh to try and promote good practice where this is carried out by land managers directly or by volunteers.
NatureScot have been granted permission from SEPA and HSE to protect trees using WOBRA deterrent paint under the mitigation scheme. It is slower to apply and slightly more costly than using mesh, but is useful for trees that would be difficult to protect using mesh either for aesthetic reasons or due to the form of the tree (often where there are wide root buttresses). For comparison a £120 tub of paint should protect 2 large trees and on average 2 trees of 50cm diameter could be protected in an hour. Again labour costs would need to be added.
Requests for advice and assistance with individual tree protection are the most common request to the mitigation scheme. Beavers rely on riparian vegetation and trees for forage. Hence under the mitigation scheme it is not the intention to prevent beavers from accessing these resources by protecting large numbers of trees, the focus is on protecting high value trees; those of heritage, landscape and particular amenity value. Since September we have assisted in providing individual tree protection in 12 locations.
Whilst tree felling can appear dramatic, most broadleaved tree species will coppice provided other herbivore browsing does not limit regrowth, in the longer term the woodland should recover. Beaver impacts will inevitably concentrate on the available woodland and hence, the wider promotion and use of riparian planting will help to distribute beaver impacts; although some stands of trees may always be preferred for their species or proximity to lodges.
Small scale tree planting took place at six sites over winter 2020/21 as resilience trials; promoting bank stabilisation and increasing the forage for beavers. These ranged from 500 trees to less than 100 and some were protected by mesh guards and others left unprotected. Although not set up as scientific trials, future monitoring should indicate the success of tree establishment.
Eight flow devices have now been installed under the mitigation scheme. Most are simple single or double pipes with a mesh cage protecting the inflow (see Figure 1). The locations where they have been installed have not been identified as important for migratory fish and hence have not yet incorporated any designs with fish ladders. Materials cost on average £400 per site and are typically installed in a single day with three people in attendance hence have been estimated to cost £1220/ flow device. Under the Management Agreements for these works, NatureScot is responsible for the monitoring and maintenance of the flow devices for the duration of the scheme. Experience to date suggests that flow devices do require some adjustment to get the levels of flow that allow water to drain from the system without promoting further beaver activity and in some situations they have required maintenance works.
Beaver exclusion projects
Three projects have installed beaver exclusion fencing using equine and high specification weld mesh; one to protect a stand of high value trees and the others as part of beaver exclusion projects. Fencing costs will be site specific and to date have been £24-27/m including labour costs.
Three water gate projects have been in development for the last year, but have yet to be installed as have to go through a detailed design, planning, flood risk assessment and commissioning process. Water gates are relatively untested as a means of excluding beavers from a sizeable area of vulnerable land. They are a hard engineering approach and are likely to be costly to install, but NatureScot are keen to trial this approach in the limited circumstances where they may be beneficial in reducing conflicts in the longer term and reducing the need for licensed control.
3.2 Scottish Beaver Forum Technical Sub-groups
There are three technical subgroups set up under the Scottish Beaver Forum with the aim of identifying and trialling innovative solutions to reducing beaver conflicts. The groups have been tasked with looking at specific issues, although there is cross-over in the approach. Two of the groups have met twice and the third only once in the last year. This is largely due to limited NatureScot staff resources to take these groups forward, but the staff resource has now been increased and we hope to accelerate the rate of progress with developing trials.
Burrowing – There are currently limited mitigation options available to address concerns about beaver burrowing into river banks, causing subsidence and erosion of river banks. There is also the particular issue of beaver burrows breaching or leading to the collapse of artificial flood embankments that are protecting lower lying land from inundation. Hence the group is tasked with looking at these issues and coming up with solutions to trial and cost in a Scottish context. The group will be looking to work with land managers that may be interested in trialling these novel approaches. This could involve trialling some of the larger scale approaches to reducing beaver conflicts that have been implemented elsewhere in Europe, for example using river restoration techniques, water margin management using wider buffer zones between crops and watercourses, riparian planting to promote bank resilience or in places consideration of natural flood management approaches.
Riparian woodland – The mitigation scheme can offer some support with individual tree protection, but it is recognised that living alongside beavers brings with it new challenges for woodland managers and also opportunities for creating and improving riparian woodlands for beavers. The remit of this group is to bring together the practical knowledge to create a ‘tool box’ for managing woodlands in the presence of beavers. This toolbox will include monitoring methods, will seeking to integrate beavers into relevant guidance, will signpost to and seek to inform grants and funding opportunities for riparian woodland planting and management and will promote communications around the experience of managing woodlands in the presence of beavers.
Environmental Support - This group is looking at the options for future support of both beaver mitigation and wider environmental management to reduce beaver conflicts and/or benefit beaver conservation. Through piloting such approaches, the Group aims to gather information to inform thinking on how these approaches can be better integrated with land management advice; where appropriate, how they could be integrated with future SRDP support including information on costs and how such measures can demonstrate public benefit.
3.3 Mitigations case study
NatureScot were initially contacted with regard to damming under railway arches (Network Rail are also heavily involved at the site) and impeded drainage of arable fields to the north of the railway line. Numerous field drains discharge into an oxbow lake which then drains out under the railway. The nature of the site has always meant that it was prone to flooding during winter months. However, the beaver dam was impeding drainage from the oxbow lake, extending the depth/duration of water levels at peak levels. Concerns were also raised that beavers were damaging areas of planted riparian woodland.
Secondly it was agreed to investigate further the potential problems of establishing new tree plantings in areas where beavers are established. For this purpose under the scheme it was agreed to plant a mixture of trees with weldmesh guards and also some without to see how effective the mesh guards were in establishing trees. Two areas were planted with trees on 28th January 2021. Ongoing monitoring will determine the success of planted trees with and without protection.
Network Rail have installed a grille on the bridge under the railway with the intention of preventing beavers from damming under the railway which would be difficult to remove safely.
The flow device required maintenance in May after a bend developed at the joint in one pipe, leading to a higher outflow level and consequent raised water level. This was straightened easily and no other issues with it have been reported to date. The flow device has been successful in allowing a steady flow of water out of the system however it should be noted that there is a longer lag time for water exiting the system meaning levels are understood to be staying higher for longer. There was always an expectation that some experimenting with levels would be necessary to get the level correct to maximise outflow without prompting increased beaver activity.
3.4 Review of scheme
We are now two years into delivering a mitigation scheme which is helping to support land managers to live along-side beavers; thereby helping to deliver some of the positive benefits for biodiversity and other ecosystem services that we know beavers can bring. We are accumulating a knowledge of the more tried and tested methods and what they cost and aim to share this information with a range of stakeholders such that there is greater collective experience of managing beaver impacts as their range increases.
We have reviewed delivery of the scheme and:
- recognise there is more to do in terms of monitoring the effectiveness of measures and this will be ongoing over the next two years.
- we are taking on board the feedback that it needs to be clearer to land managers what is included in the scheme and where the responsibilities lie for ongoing maintenance and will update our web guidance accordingly.
- We have increased the specialist skills in the Beaver Team and in contractors appointed through a Framework Agreement to deliver a range of advice and management interventions on behalf of NatureScot. Our Beaver Mitigation Scheme Project Officer is now focused on supporting the work of the Technical Sub-groups. In addition, NatureScot is looking to establish support for volunteers keen to help carry out a range of monitoring and mitigation tasks.
The operating budget for the mitigation scheme in the financial year 2020/21 was £91K, however, due to COVID related delays in some projects, the actual spend was approximately £40K. The allocated budget for 2021/2022 is also £90K. It is intended the scheme will help to inform how beaver mitigation can be supported in the longer-term and how wider environmental measures that could help to reduce beaver conflicts could be integrated with future rural support payments.
4. Beaver licensing 2020
It is now two years since beavers received protected species status on 1st May 2019. This report includes a summary of beaver licensing from 1st January 2020 to 31st December 2020 and provides an update to the beaver licensing summary published for the period May to December 2019.
4.1 Demand for licenses
NatureScot had been in discussion with many of the applicants in the run up to beavers becoming EPS. Prior to this we had accumulated a detailed knowledge of beaver impacts over the previous 15 years through the work of the Tayside Beaver Study and NatureScot’s provision of beaver advice and mitigation. Hence there was an existing understanding of the serious social and economic impacts that beavers can have particularly in Prime Agricultural Land in this locality and there was existing demand for licences in 2019. Of the 45 licences issued in 2019, one was for a short time period for specific actions and the remainder continued or were renewed into 2020.
Seventeen new licences were issued in 2020. Although 2020 was affected by COVID restrictions in many ways, NatureScot were still able to deal with licensing requests where needed. Hence the fewer requests for new licences likely reflects that the main areas experiencing significant impacts had already been issued with licences in 2019. The nature of licence requests were also slightly different in 2020 from those that were issued in 2019 principally in relation to serious agricultural damage. In 2020 five licences were issued in relation to impacts on public infrastructure requiring dam removal or modification; roads (2), culverts (1), rail culvert (1), national cycle route (1) and one licence in relation to forestry operations; to allow a flow device to be installed to protect a forest road.
Of the 17 new licences issued, five licences related to mitigation works; three where flow devices were being installed or modified and two with a view to excluding beavers from conflict areas by installing fencing and grilles.
From a geographic perspective, the licences issued principally relate to the wider Tay catchment (east to west from Forfar, to Lochearnhead and north to south from Pitlochry to Gleneagles) and for the first time included a licence in Argyll.
Of the 17 new licences issued, 11 were for dam removal or modification and six permitted the lethal control of beavers. Of the lethal control licences, five were on land classed as Prime Agricultural Land and one licence relating to non-PAL land was issued pending a site visit (and later revoked as it had not been possible to carry out the site visit).
4.2 Licence returns
In total 52 licence returns were received. Licence holders were reminded in advance of the requirement to submit a return by the end of January 2021 for actions carried out in the calendar year 2020. Reminders were sent to those not received by this date (2 emails) and a follow up call was made to those still not received by mid-March. Further to this six licences were revoked for failure to submit an annual return.
|Number of Licences|
|Catchment||Issued in 2019||Issued in 2020||-||Total issued (those current)||-|
|-||All||Includes lethal control||All||Includes lethal control||All||Includes lethal control|
|Isla||24||21||6||4||30 (28)||25 (23)|
|Earn||12||11||2||0||14 (12)||11 (11)|
|Tay||8||7||8||2||16 (12)||9 (6)|
|Total||45||39||17||6||62 (53)||45 (40)|
4.3 Use of licences
Of the 52 licences with returns, 35 (67%) reported having taken some action in 2020. The 33% not taking action reflects a variety of circumstances; where beaver activity has been lower than previously, where actions have been taken elsewhere or collectively to address impacts and where licence holders may have engaged in trapping as alternative to lethal control (covered under a separate licence).
Sixteen licences reported only having removed dams, six reported having removed dams and carried out lethal control and 13 having only carried out lethal control.
Licences used in 2020 (of 52 returns)
|Number Dams (removed or modified)||Number beavers killed|
4.4 Numbers of dams removed in 2020
Beaver dams are principally protected because they can be associated with breeding (natal) lodges and burrows and hence are important to successful breeding. NatureScot advise that the removal of any dam, other than one that has been very recently built (we advise less than 2 weeks old), risks damaging or destroying a breeding site or resting place or disturbing beavers. This is because it can be very difficult to know if a breeding site or resting place is present, and particularly chambered burrows, because they may not be visible above the water line. However, dams that are less than two weeks old are unlikely to be used in this way and hence NatureScot advises that these do not require a licence for their removal. Whilst many land managers can manage the impacts of beavers through timely removal of beaver dams where they occur in locations that would lead to problems, licences are issued to permit the removal of dams that have evaded detection and have become established. It is appreciated that resources may not allow all potential watercourses to be regularly inspected at all times and hence that these situations do arise and can need to be removed in order to prevent serious damage occurring.
The figures above reflect dam removal reported in licence returns. It is noted that these figures may include some removals that were done within the two week window as the return forms to date has not made this distinction clear, but will do so in future.
As mentioned above, some of these actions reported relate to dam modification whilst flow devices were installed or dam notching to reduce water levels at key periods or as a temporary measure e.g. to allow the road surface to be raised to reduce the risk of flooding. The remaining dam removals took place on Prime Agricultural Land (15 licences) and non -Prime Agricultural Land (2 licences).
4.5 Number of beavers killed under licence in 2020
From the returns received the total number of beavers killed under licence was 115. This number is higher than the figure of 87 recorded for the nine months post EPS protection reported in 2019; noting the figure for 2020 is for the full calendar year. No lethal control was reported to have been carried out in the Kit Dependency Period (KDP, 1st April to 16th August). Most control was carried out in the Autumn (Figure 2). Lethal control was carried out only on land either classed as Prime Agricultural land (18 licences) or assessed as having the qualities of PAL land (1 licence).
4.6 Numbers of beavers trapped and translocated
One licence remains in place that permits live-trapping of beavers by an experienced ecologist from sites where lethal control may otherwise have been employed. The licence also permits other forms of beaver mitigation and management.
As per the recommendations in the 2019 licensing report, in 2020 NatureScot made a concerted effort to engage with all lethal control licence holders and facilitate trapping and translocation to licensed projects (which this year were solely in England) if and when beaver removal was considered necessary. The 45 licence holders (at the time) were contacted mainly by phone (August-early October) and by email in a few cases where phone contact was not successful. A number of properties were already known to the experienced trapper acting on behalf of the projects in England having trapped in these locations in 2019 and in some cases prior to this.
These conversations highlighted that trapping needs to be responsive to beaver activity and impacts. Land managers were notably busy themselves during harvest with less time available for monitoring of impacts. A couple of licence holders remarked they had been managing impacts through dam removal and hence had not yet required to make use of lethal control. The licence holders for 35 licences (77%) indicated a willingness to try trapping and their contacts were passed to the trapper who subsequently made contact with them. The licence holders for five licences preferred to continue to use lethal control over trapping and no responses were received from three licence holders.
These exchanges sought to encourage a dialogue when issues started to present. There appeared to be some reservations about the effectiveness of trapping where it had been tried previously and had been unsuccessful. For trapping to be successful, beavers need to be active on the land at the time, there needs to be suitable trapping locations (regular runs on flat ground, not subject to rapid fluctuations in water levels) and the traps need to be sufficiently attractive as compared with naturally available food. Hence trapping success can vary over time and we have encouraged this approach even where it has previously been unsuccessful. Now contacts have been established between licence holders and the trapper acting on behalf of licensed translocation projects, it is hoped that a more regular dialogue can be maintained to facilitate trapping where this is needed and practical.
Eighteen beavers were trapped in the calendar year 2020 on 10 properties where lethal control is permitted under licence. Trapping was also carried out at a further three locations where lethal control licences had not been issued, but where there are ongoing mitigation projects to exclude beavers to prevent serious damage (one on public safety grounds). A further 14 beavers were trapped at these locations, hence in total 32 beavers were trapped. Thirty one of these animals were translocated to licensed projects in England (as per Table 4) and one animal was re-released locally.
|Release site project||Number of beavers*|
|Hamthey Estate, Cornwall||1|
|Honicote Beaver Project, National Trust||6|
|Foxfield Farm, Cumbria||2|
|Cabilla Farm, Cornwall||2|
|Lowther Beaver Project, Cumbria||2|
|Broadridge Farm, Witheridge, Devon||5|
|Seal Sanctuary Cornwall||2|
|Cheshire Wildlife Trust||2|
|Sussex Beaver Project, Knepp Estate||2|
|Poole Harbour Farm, Plymouth City Council||2|
|Dorest Wildlife Trust||1|
*In some cases these releases supplement animals translocated in previous years or have been added to in 2021 and will be reported on in 2021.
** Noting one beaver was released locally in Scotland.
4.7 Impact of licensed removal of beavers on Favourable Conservation Status
NatureScot must not grant a licence unless satisfied that the action authorised will not be detrimental to the maintenance of the population of the species concerned at a favourable conservation status in their natural range (FCS). FCS is assessed with respect to the species in its natural range. In the case of beavers which have been reintroduced to Scotland their natural range is considered to be the range within which they have been formally permitted to remain i.e. in Knapdale in Argyll, and in Tayside and Forth. As there was no reference population when the Habitats Directive came into being, NatureScot have regarded the conservation status as ‘favourable’ when:
- population dynamics data on the species concerned indicate that it is maintaining itself on a long-term basis as a viable component of its natural habitats, and
- the natural range of the species is neither being reduced nor is likely to be reduced for the foreseeable future, and
- there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis.
An assessment was carried out of the impact of licensed removal of beavers from the Forth and Tay catchment with reference to control and trapping data from 2019 and 2020.
The analysis looked at the:
- numbers of individuals and territories affected by control and trapping
- total number of animals shot or trapped per territory (control intensity)
- changes in the number of territories between surveys
- percentage of the population removed by shooting or trapping.
This assessment was conducted at three resolutions: the local scale (persistence of territories and the numbers removed per territory), the medium-scale (persistence of territories within the watercourse) and the large-scale (persistence of territories within the sub-catchment (Isla, Earn, Tay etc).
Locational data from licence returns were used to match control and trapping records to the nearest beaver territories from the 2017/2018 survey (Campbell-Palmer et al. 2018) and to the 2020-2021 survey (Campbell-Palmer et al. 2021a). Where points fell more than 0.5km from a territory the record was assumed not to be a member of a territory1. The 2019 returns data follows a year after a survey and so there will have been new territories established in the interim (see Campbell-Palmer et al. 2021a) whereas the 2020 returns data overlaps the survey period and so no new territories will have established and is unlikely the loss of territories after control would be picked up in this timeframe (as indicated by an absence of fresh signs).
At the medium scale, control and trapping records were matched to 22 stream sections, with the Forth treated as one section. At the large scale control and trapping records were matched to a sub-catchment (Earn, Forth, Isla, Tay).
|Catchment||Number affected by licenced control (of 251, 2021 territories)||Number affected by licenced trapping (of 251, 2021 territories)||Total number affected by licenced removal|
|Total||26-29 (10-12%)||10 (4%)||31-34 (12-14%)|
* n.b. both trapping and control took place in a number of territories.
1 Where no territories were identified within a watercourse where control had occurred, one territory was assumed to be present to calculate the rate (mean number per territory).
4.7.1 Numbers of individuals and territories affected by control and trapping
In 2019, based only on individuals which were allocated to a territory, beavers were shot at 14 (12%) of the 114 territories identified in the 17/18 survey and 22-26 (9-10%) of the 251 territories identified in the 20/21 survey. Of the 21 not allocated to 17/18 territories, 19 were probably from seven new family groups or territories and two were singletons. Together these may have represented nine new beaver territories for 2019. Based on Campbell-Palmer et al.’s (2021a) revised assessment of territories, there may have been 193 territories in 2019. The total 23 territories (14+9) still represents 12% of the estimated 193 territories.
In 2020, based only on individuals allocated to a territory, beavers were shot within 26-29 (10-12%) of the 251 territories identified in the 2020-2021 survey. Therefore a similar proportion of territories were affected in both years. The remaining beavers in 2020 were shot at six other locations of which four were possibly newly establishing family groups and two singletons.
Trapping in 2019 took place at four (3.5%) of the territories identified in the 2017-2018 survey and two new locations. One territory was also subject to lethal control and so the total number of territories affected by control and trapping was 17. In 2020, trapping took place at ten (4%) of the territories identified in the 2020-2021 survey and two other locations. Five of those territories were also subject to lethal control and so the total number of territories affected was 31-34.
A total of 202 individuals were reported shot from licence returns over both years, 87 in 2019 and 115 in 2020. Campbell-Palmer et al. (2021a) estimated a 30% annual increase in the number of beaver territories between 17/18 and 20/21 (i.e. a 120% increase over the whole period). If the increase in territories involves a comparable increase in the number of individuals in the population, then a similar proportion of the population was shot in both years2. A total of 18 individuals were removed through trapping in 2019 and 31 in 2020. Adding these to the figures above gives 105 removals in 2019 and 146 in 2020, which reflects 14.3% and 15.3% of the population in 2019 and 2020 respectively.
2Using the revised estimate of their being 193 territories in 2019 - control of 87 animals reflects 11.9% of 733.
In 2020 115 animals from a total of 251 territories = 12.1% (of 954).
4.7.2 Total number of animals shot or trapped per territory (control intensity)
Beavers are highly territorial animals; territories are established and defended by family groups which can vary significantly in size and structure. Controllers are advised to remove the whole family group to prevent impacts recurring and to protect beaver welfare; noting this approach will lead to higher numbers of animals shot than removing individuals.
Of the 87 individuals shot in 2019, 65 beavers were allocated to 17/18 territories and 71 to 20/21 territories. Of those shot in 2020, 103 beavers were allocated to 20/21 territories. A mean of 4.6 (2019, using 17/18 territories), 2.7 (2019 using 20/21 territories) and 3.7 (2020 using 20/21 territories) animals were shot per territory, though this is skewed by some high figures that likely come from controllers shooting in >1 territory but reporting the same rough locality. The median number from all age classes shot per territory was two in both years. The most common number was one (2020) or two (2019) per territory. Some shot beavers will have been singletons moving into new areas which may bring them into conflict with human land use, e.g. on agricultural ditches.
For seven territories, controllers did not provide an estimate of the group size. The average group size reported by controllers (mean group size 1.69 ± 1.53 animals (range 1-8, median = 1) suggests some controllers are underestimating the size of the group they are controlling, which will reduce the effectiveness of the control as a tool in resolving conflict.
4.7.3 Changes in the number of territories between surveys
Local effects of control
From the returns in 2019 71 (82%) of beavers were shot at territories identified in the 2021 survey. Five of these were shot at locations not identified as territories in the 2018 survey (i.e. new territories). Of the remaining 16 that were shot outwith territories identified in the 2021 survey, three were shot at territories identified in the 17/18 survey, i.e. two territories that had beavers shot in 2019 that were unoccupied in 2021. The remaining 13 animals were shot at locations not identified as a territory in either year.
No beaver trapped in 2019 was taken from a territory identified in 17/18 that was not identified as a territory in 20/21 though four were taken from two locations not identified as territories in either year.
From the returns in 2020, most (90%) of beavers were shot at territories identified in the 2021 survey. Thirty five of these were shot at locations not identified as territories in the 17/18 survey (i.e. new territories). Of the remaining 12 that were shot outwith territories identified in the 2021 survey, half (six beavers) were shot at three territories identified in the 17/18 survey. It is likely that these six animals were recently re-establishing at those locations, rather than having been resident for a long period.
No beavers were trapped in 2020 at a territory identified in 17/18 that was not identified as a territory in 20/21 though six were taken from two locations (one matching a location trapped in 2019) not identified as territories in either year.
Hence the majority of beavers were not shot or trapped at territories that later disappeared. In the four territories where this happened, it is not possible to conclusively attribute the territory loss to the licensed control and for two of the territories, only one animal was taken from each. In many other territories also, too few individuals were removed (i.e. one animal) to result in the loss of a territory and it is unlikely that all of those territories where single animals were shot were singleton territories. However, the 2020-2021 survey may not have identified recent territory loss from animals shot in 2020, especially the season from Aug-Dec when 82 animals were shot. A follow-up check of a subset of 2020-2021 territories that experienced control in late 2020 will be carried out as part of ongoing monitoring of the impacts of licensing control.
Overall, lethal control and trapping may have stopped the establishment of nine territories over both years. Combining this figure with the four territories that disappeared between the surveys, at most, the rate the population grew was reduced by failure of 13 (5%) of territories.
Medium scale effects
Between the two surveys the number of territories on stream sections increase by a mean of 2.6x and no stream section showed a decline in territory numbers. There is no clear relationship between numbers trapped or shot in either 2019 or both years, and the change in territory numbers in the stream section. However, the increased in territories did show a positive relationship with the rate of control (the numbers shot or trapped per territory per year). This was significant for both 2019 control rates (Pearson’s, r = 0.732, t = 4.81, df=20, p < 0.001) and combined 2019-2020 control rates (r = 0.678, t = 4.13, df=20, p < 0.001). Though this relationship was skewed by a small number of sections with high rates of control, the relationship was still positive when rates were ln transformed for 2019 (r = 0.675, t = 4.10, p < 0.001) and combined (r = 0.647, t = 3.80, p = 0.001). Most likely this positive correlation reflects that higher rates of control arise where there are beavers establishing new territories (i.e. population increase leads to an increased control rate), which are likely to be in marginal habitats such as agricultural ditches where conflict is more likely.
Large scale effects
No clear pattern was visible for changes in territory number in relation to beaver control activity across the four sub-catchments. The two sub-catchments with the lowest rate of territory increase (Earn and Tay) had moderate to low rates of control whereas the Isla, had both the greatest relative increase in territory number and the highest rates of control.
4.7.4 Percentage of the population removed by shooting or trapping
Based on the calculation of population size based on the number of territories and an average group size, the overall removal rate in 2019 was 14.3% of the population, and in 2020 it was 15.3%. Removal rates within steam sections (medium scale) were 0 - 47% in 2019 and 0 - 61% in 2020. In both years, five of the 22 stream sections experienced removal rates above 25%. These section were mainly in the Isla sub-catchment. In both years, 14 sections experienced removal rates of 5% or less.
Two separate studies have found dramatic differences in sustainable removal rates Eurasian beavers. Parker et al. (2002) found an annual removal of 24% of the population was unsustainable for a population in Norway whereas Dezhkin & Safonov (1966 cited in Parker et al. 2002) indicated that 30% of beavers could be removed without affecting the sustainability of a population in Russia. In Tayside, removal rates exceed 25% in several stream sections without a visible impact on the population. There may be several reasons for this:
- The 2020-2021 survey overlapped the 2020 control period and so any declines are not yet visible. However, some impacts of high levels of removal in 2019 should be visible (Parker et al. 2002 saw a decline from the first year of their study) but none are evident.
- Most of the control conducted in Tayside has been in autumn, where a larger proportion of sub-adults may be taken. According to the Tayside returns (2019 and 2020 where age class was provided unambiguously), 43% of individuals shot were not adults.
- The study population in Norway may have had a lower reproductive rate (<1 kit per territory recorded in a neighbouring river, Campbell et al. 2017) than that currently in Tayside (1.9 per territory, Campbell-Palmer et al. 2015).
- Though the control rate within a minority of stream sections were high, removal rates across the wider area (i.e. sub-catchment) were lower (Figure 3) and therefore vacancies in territories from licensed control or trapping are filled relatively quickly through immigration from other stream sections.
4.7.5 Overall assessment of FCS
As noted above there are three elements to the assessment of FCS relating to population dynamics, the natural range and habitat extent.
- In relation to the population parameters, it is clear that, where currently found, the beaver is maintaining itself on a long-term basis as a viable component of its natural habitats. The 2020/2021 Tayside survey concludes that there has been an annual 17-30% increase in beaver territories since the 2017/2018 survey indicating a rapid rate of expansion. Beaver density has also increased. Whilst a small number of territories have been abandoned for various reasons, overall, the number of beaver territories have significantly increased. Further, it is likely that this rate of increase will continue as their range continues to expand and infill.
- The current natural range of beaver in Scotland is limited compared with its historic range. There is the Knapdale population and the larger Tayside one. Overall, its current natural range is expanding, with a reinforced population at Knapdale and expansion in parts of Tayside as noted.
- Beaver habitat has been mapped within its current range, and more widely across Scotland and it is clear that there is a lot of suitable habitat available. Presently the beaver is actively expanding its current natural range; indicating that there is sufficiently large habitat available to maintain its populations on a long-term basis.
Overall, the conservation status of beaver in its current natural range may be assessed as favourable and improving as it gradually expands its current range across suitable habitat in Scotland. There is no reason why the increasing pattern seen to date in terms of territory number and range expansion will not continue given the amount of suitable habitat known to exist beyond the beaver’s current range. There is a need to monitor the situation in future years though to ensure improvement is being maintained.
Our analysis at the level of territories and stream sections highlights that the intensity of control has the potential to impact on the local population. However, this is the intention of the licenced removal by control or trapping as in issuing licences they have been assessed as necessary to prevent serious damage and the advised approach is to remove the family group. However in continuing to issue and renew licences, NatureScot needs to ensure that local meta-population ‘sinks’ do not affect the viability of the population as a whole. Hence we plan to continue to monitor territories affected by recent control in order to keep under review these medium scale impacts. A population model has previously been produced (Shirley et al. 2015) which can be modified and used to explore licensed control/ removal scenarios further and if there are critical thresholds of removal that would restrict further overall population expansion. We have been working with researchers at the University of Newcastle to further develop these modelling tools.
4.8 Compliance monitoring
Checks have been carried out on the returns submitted by licence holders and accredited controllers for 2020.
Kit Dependency Period
No animals were reported to have been controlled during the Kit Dependency Period hence there appears to have been good observance of this sensitive period. Thirteen dams were reported to have been removed during the Kit Dependency Period. The current licences have a condition that requires licence holders to notify NatureScot if they carry out actions during the Kit Dependency Period. No dam removal notifications were received. However, it is not possible to tell from the returns submitted if the dams removed were more than two weeks old or what the exceptional circumstances were that required they were removed. Following consultation with the Scottish Beaver Forum we have decided that licences will no longer operate during the Kit Dependency Period and that exceptional licences will be needed for actions at this time; removing any ambiguity and affording greater protection to beaver welfare.
The information provided in accredited controller returns provides details of where and when beavers have been shot, the age/status of the beaver, various biometric measures (weight, tail length and width), details of whether it was shot on land or in water, what equipment was used to aid observations, what ammunition was used, shot placement and whether or not the carcass was retrieved and submitted for post mortem. The return form also asks for the number of beavers in the family group from which the beaver was shot. Collectively this information helps to demonstrate that beaver control has followed best practice. Whilst the quality of information submitted is generally good, there is scope for improvement in some returns. We intend to make it clearer what information is requested going forward as a condition of the licence. Details of biometrics are understandably missing where it has not been possible to retrieve carcasses for health and safety reasons where animals have been shot in water.
A 6 figure grid reference was supplied for 54% of animals shot, with a broader description of the location in other cases. The age/status of the animal was recorded for 93% of animals shot (of which 63% were adults, 34% were sub-adults and 4% were kits (%s rounded up) in 2020. It should be noted it is not possible to determine the sex of a beaver without detailed examination hence this information is not requested.
Eighty percent of beavers were recorded as being shot in water, with the remainder on the bank or at a dam. Details of the calibre of ammunition used was provided for 77% of animals shot. Ninety percent of kills were reported as head/shoulder shots, with 7% chest shots and 3% unreported. Twenty six percent of carcasses were reported to have been retrieved, which is slightly more than those reported to have been shot on land.
The number of beavers in the family group was reported for 83% of animals shot; 6% indicated this was not known and no information was provided for 10% of animals. The guidance accompanying lethal control licences and the accredited controller training highlights that controllers should establish the composition of the family group causing the impacts of concern by carrying out observations prior to carrying out control and that they should target the whole family group.
A number of site visits with accredited controllers have been carried out to help develop the understanding about what information is requested and how it is being used. The provision of carcasses for post mortem is an area that NatureScot and the Scottish Beaver Forum as a whole, have been keen to promote. Post mortems provide important information to improve guidance and training of accredited controllers; they contribute to our knowledge of the health status of wild beavers, issues relating to public health and population genetics. For example, two recent publications are largely based on samples collected for post mortem or beavers trapped as part of management operations (Campbell-Palmer et al. 2020 and Campbell-Palmer et al. 2021b).
4.9 Beaver post mortems
Post mortems were carried out on five beavers from Tayside by SRUC Veterinary Services between June 2020 and March 2021 inclusive. Three, an adult male and two sub-adult males, were shot. One carcass indicated bullet placement was not in the recommended area to best ensure a humane dispatch, the other two animals appeared to have been shot according to best practice.
Four of the animals were male, including two sub-adults and one that was either a sub-adult or an adult in poor condition. The other beaver was an adult female. Causes of death for the two that were not shot were unidentified and the injuries sustained may have been obtained from territorial fights with other beavers.
All except the emaciated male tested positive for the trematode parasite Stichorchis subtriquetrus, which have been reported in this population previously (Campbell-Palmer et al. 2013). Microbiology testing found Yersinia enterocolitica (one individual), Yersinia ruckeri (one individual, possibly associated with a sewage works upstream), Aeromonas spp. (one individual), Moellerella wisconsensis (one individual), Streptococcus (one individual, from abscess), non-haemolytic Escherichia coli (one individual), Lactococcus lactis (one individual), Paeniclostridium sordellii (one individual).
Overall, the sample of beavers examined is too small to draw any conclusions on welfare and disease risks (though previous research indicates disease risk is low, Campbell-Palmer et al. 2021b). The post mortem of beavers shot or found dead in Tayside needs to continue so that this information can continue to be assessed.
4.10 Review of beaver licensing
Beaver licensing is still relatively new and NatureScot generally aims to review our licensing approaches and make changes where appropriate. As it is now two years since beaver licencing was introduced we have carried out a review that has looked at compliance and issues around wording of conditions to improve reporting and remove any ambiguity in the wording.
Changes are planned with the effect that licences will no longer cover the period of the Kit Dependency Period and licence holders that require to take action during this time will need to apply for an exceptional licence. The licence conditions have been reviewed and will more clearly distinguish between those actions that must be carried out and new Codes of Practice will set out best practice for carrying out lethal control and separately dam removal. In particular this will highlight the need to monitor and take steps to remove the whole family group whilst ensuring the beavers are from the family group that are causing the serious impacts. It also planned to map the area covered by a licence to remove any ambiguity around where they apply.
Many beaver licences were issued for a period of two years and hence have recently expired.
Information on individual licences has been reviewed, informed by new information arising from the recent survey, from casework reports; from a number of site visits requested by NatureScot, or where mitigation projects have removed the need for/ nature of some licences. It is intended to issue renewals where appropriate, ahead of the end of the Kit Dependency Period on 17th August.
As per 4.7 the impact on Favourable Conservation Status of renewing individual licences for lethal control has been considered. We will examine the location of any new licence applications with reference to the stream sections they occur within (medium scale) with a view to ensuring the issuing of that licence would not have a negative (cumulative) impact on population growth.
5. Moving Forward
- The recent survey has found a rapid expansion in beaver territories, combined with range expansion and it is expected this trend will continue as beavers move into unoccupied areas of suitable habitat.
- NatureScot will continue to provide a Scottish Beaver Mitigation Scheme to assist land managers to live alongside beavers and where possible to be proactive in ‘beaver proofing’ areas as beavers continue to expand their range.
- We anticipate that demand for protected species licences will continue in high conflict areas, but are continuing to explore novel solutions to some of the more challenging issues that are currently lacking mitigation approaches through the Technical Sub-Groups of the Scottish Beaver Forum. In turn it is intended the scheme will inform future support mechanisms for beaver mitigation and as a nature-based solution with wider environmental objectives.
- We will continue to encourage, promote and facilitate the use of trapping as an alternative to lethal control where this is practical and may be of wider benefit to beaver conservation and the delivery of ecosystem services.
- We will keep under review the levels of beaver control being exercised to ensure that there is not a detrimental impact on the improving conservation status of the species; ensuring that beavers continue to expand in their range and number of territories. In particular we will employ modelling approaches to provide an empirical basis for these decisions. We will review the timescale for repeating the survey of the entire population or possibly more focused survey effort in areas where there are removals under licence and on edge of range.
- We have made some changes to the protected species licensing regime and will continue to review and adapt this as necessary.
Campbell, R.D., Rosell, F., Newman, C., & Macdonald, D.W. (2017) Age-related changes in somatic condition and reproduction in the Eurasian beaver: Resource history influences onset of reproductive senescence. PLoS ONE 12(12): e0187484.
Campbell-Palmer, R., Dickinson, H., Wilson, K. & Rosell, F. (2015). Group size and reproductive rates within the Tayside beaver population, Perthshire. Scottish Natural Heritage Commissioned Report No. 802.
Campbell-Palmer, R., Girling, S., Pizzi, R., Hamnes, I. S., Øines, Ø., & Del-Pozo, J. (2013). Stichorchis subtriquetrus in a free-living beaver in Scotland. Veterinary Record, 173(3), 72-72.
Campbell-Palmer, R., Puttock, A., Graham, H., Wilson, K., Schwab, G., Gaywood, MJ. & Brazier, R.E. (2018). Survey of the Tayside Beaver Population. Scottish Natural Heritage Commissioned Report No. 1013
Campbell-Palmer, R., Puttock, A., Needham, R.N., Wilson, K., Graham, H. & Brazier, R.E. (2021a). Survey of the Tayside Area Beaver Population 2020-2021. NatureScot Research Report No. TBC
Campbell-Palmer, R., Senn, H., Girling, S., Pizzi, R., Elliott, M., Gaywood, M. & Rosell, F. (2020). Beaver genetic surveillance in Britain. Global Ecology and Conservation, 24, e01275.
Campbell-Palmer, R., Rosell, F., Naylor, A., Cole, G., Mota, S., Brown, D., Fraser, M., Pizzi, R., Elliott, M., Wilson, K., Gaywood, M. & Girling, S. (2021b) Eurasian Beaver (Castor fiber) health surveillance in Britain: Assessing a disjunctive reintroduced population. VetRecord 118, 8, e84.
Parker, H., Rosell, F., Hermansen, T. A., Sørløkk, G., & Stærk, M. (2002). Sex and age composition of spring-hunted Eurasian beaver in Norway. The Journal of wildlife management, 1164-1170.
Shirley, M.D.F., Harrington, L.A. & Mill, A.C. 2015. A model simulating potential colonisation by Eurasian beaver (Castor fiber) following reintroduction to Scotland. Scottish Natural Heritage Commissioned Report No. 814.
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