Appendix 2 – Spey catchment: beaver feasibility and potential release site assessment
Spey Catchment: Beaver Feasibility and Potential Release Site Assessment
October 2023
Prepared as part of a wider feasibility study into the potential return of beavers to Cairngorms National Park by:
Dr Róisín Campbell-Palmer, Dr Alan Puttock, Dr Robert Needham and Prof Richard Brazier
*cover photo, main channel of River Spey, south of Blargie © Alan Puttock
Contents Introduction and Aims 3 Modelling of Beaver Habitat Suitability Spey Catchment 4 Beaver Habitat Suitability Modelling 4 Beaver Vegetation Index (BVI ‑prerequisite for BHI modelling) 5 Beaver Habitat Index model (BHI) 5 Beaver Habitat Index maps and summary statistics for study area 6 Beaver Dam Capacity Modelling of Spey Catchment 8 Beaver Dam Capacity (BDC) model summary 8 Beaver Dam Capacity Model maps and summary statistics for the study area 9 Beaver habitat and dam capacity model summary 10 Aspen Mapping 11 Beavers and Fish in the Spey 14 Potential Release Site Assessments 22 Site Mapping Summaries: 23 Insh Marshes 23 31 32 33 34 35 36 Uath Lochans 36 41 42 44 Key recommended release sites, connectivity, and dispersal 45 Conclusions and Next Steps 46 References 47 Appendix 1. Datasets used 51 Appendix 2. Caveats for use 52 Beaver vegetation and habitat index 52 Beaver dam Capacity Model 53
Introduction and Aims This report was commissioned by the Cairngorms National Park Authority (CNP) to investigate the habitat feasibility of the Spey catchment to support the restoration of Eurasian beavers (Castor fiber). Potential release sites for first releases (mid-River Spey area only) have been identified, prioritising landowners that may support any release licence application. Other sites have been investigated and though they may not be proposed as release sites, could support beaver colonisation as any population expands naturally.
Following initial feasibility work and the subsequent decision to proceed with bringing beavers back to the Cairngorms, the Park Authority are keen to undertake further assessment work to inform potential release site selection, likely population dynamics, dispersal routes and areas of likely future colonisation, alongside further assessment of potential impacts (positive or negative). This report addresses some of these aims by building on an initial feasibility study, on ground experience and knowledge combined with the deployment of models developed at the University of Exeter, and many years’ experience by these authors of beaver restoration dynamics. We present habitat suitability and beaver dam capacity in support of understanding the distribution of likely beaver populations in the future at the landscape scale across the Spey catchment.
The habitat suitability and the capacity for beavers to dam channels within the study areas was assessed using beaver modelling tools developed by researchers at the University of Exeter (Graham et al., 2020). These modelling tools consist of a Beaver Habitat Index (BHI) model and a Beaver Dam capacity (BDC) model.
There is a requirement to complete an analysis of river catchments to assess their suitability for supporting populations of beaver. Beaver habitat suitability is determined primarily by vegetation suitability which has been classified nationally using a Beaver Vegetation Index (BVI) as well as access to water bodies. Together these two factors have been incorporated into a Beaver habitat Index model (BHI). BHI has been run nationally to develop a high resolution (5m) continuous raster product that can inform local decision making with regard to beaver reintroduction. BHI classifies habitat suitability from 0 (No access to vegetation — not suitable) to 5 (Highly Suitable). It must be clarified that this habitat model is a simplified representation of reality and caveats associated with the model are listed in appendices.
Beavers are also well known as ecosystem engineers, having the capacity to change environments to suit their needs. The beaver engineering activity that has the greatest capacity to modify ecosystems is dam building. Dam building and the creation of ponded surface water has the ability to bring benefits (i.e., for biodiversity, water storage, flow attenuation) but also potentially management and conflict (i.e., localised inundation of land, blocking of critical infrastructure). BDC classifies reaches from no capacity for dam building to a pervasive capacity for damming.
Modelling of Beaver Habitat Suitability Spey Catchment Beaver Habitat Suitability Modelling Summary Description: Production of a continuous description of habitat suitability for beaver. First a vegetation suitability index is created using multiple high-resolution spatial datasets from Ordnance Survey, CEH and Copernicus will be combined to provide detailed land cover/vegetation information which is classified based on empirical field observation of beaver habitat and preference. Vegetation suitability is combined with additional parameters describing stream networks and water bodies. Whilst beaver habitat suitability is primarily defined by vegetation suitability, beavers also require water for security and movement. Therefore, accessibility to water bodies (i.e. channels, ponds, and lakes) will
also determine the viability of beaver occupancy and therefore are required to classify habitat accurately.
Outputs: This product provides a high-resolution (5m cell size) resource (raster .tiff format) for describing habitat suitability for beaver. This dataset can allow the user to explore which landscapes were most (or least) suite to beaver reintroduction and also to understand where habitat enhancement might be useful to support future reintroduction.
Beaver Vegetation Index (BVI ‑prerequisite for BHI modelling) Vegetation is important for classifying beaver habitat (Hartman, 1996; John et al., 2010; Pinto et al., 2009; St-Pierre et al., 2017). It was therefore critical to establish a reliable Beaver Vegetation Index (BVI) using nationally-available spatial datasets. No single dataset contained the detail required to depict all key vegetation types. Therefore, a composite dataset was created from: OS VectorMap data (Ordnance Survey, 2018), The Centre for Ecology and Hydrology (CEH) 2015 land cover map (LCM) (Rowland et al., 2017), Copernicus 2015 20 m Tree Cover Density (TCD) (Copernicus, 2017) and the CEH woody linear features framework (Scholefield et al., 2016).
Vegetation datasets were assigned suitability values (zero to five). Zero values were assigned to areas of no vegetation i.e. buildings and values of five were assigned to favourable habitat i.e. deciduous woodland. Values were assigned based on a review of relevant literature (Haarberg and Rosell, 2006; Jenkins, 1979; Nolet et al., 1994; O’Connell et al., 2008), field observation and comparison with satellite imagery. Vector data were converted to raster format (resolution of 5 m). TCD data were resampled to 5m and aligned with converted vector layers. An inference system was used to combine these four raster datasets to create the BVI. The workflow prioritises the reliability followed by the highest value data.
Examples of highly suitable land (graded 5) include broad-leaf woodland, mixed woodland and shrub; examples of suitable vegetation (graded 4) include shrub and marsh; examples of moderately suitable (graded 3) include coniferous woodland, marsh, shrub and unimproved grassland; examples of barely suitable (graded 2) include reeds, shrub and heathland and boulders, neutral grassland; examples of unsuitable (graded 1) include heather, acid grassland, unimproved grass and boulders, bog; examples of no accessible vegetation (graded 0) include shingle and sand, buildings, rock, urban and saltwater.
Beaver Habitat Index model (BHI) Whilst vegetation is a dominant factor in determining habitat suitability for beaver, so is proximity to a water body (Gurnell et al., 2008), with beavers being strong swimmers, using water bodies both to provide security, as a means of escaping predators and to access foraging areas. It is thought that most foraging occurs 10 m of a watercourse/body (Haarberg and Rosell, 2006), and rarely above 50 m (Stringer et al 2018). However, greater foraging distances have on occasion been observed and as in Macfarlane et al., 2015 100 m has been accepted as a maximum distance in which the vast majority of foraging occurs. Therefore, to determine suitable habitat for beaver incorporating both BVI vegetation suitability and water accessibility a 100m buffer was applied to water bodies. To do this the OS mastermap river network and OS vector in land water bodies were combined to get the best readily available national waterbody and water course coverage.
Whilst BVI was run nationally on a 5 m scale it is best viewed as a preparatory step for BHI (and later BDC) modelling and is superseded in usefulness by the BHI dataset. It is strongly recommended that most analysis and management applications such as this study use BHI i.e. if there is an area of preferred
vegetation such as willow woodland, more than 100 m from a waterbody it is thought inaccessible to beaver and therefore does not form suitable habitat.
Both BVI and BHI use a scoring system of zero to five (Table 1). Scores of five represent vegetation that is highly suitable or preferred by beavers and that also lies within 100 m of a waterbody. Zero scores are given to areas that contain no vegetation or are greater than 100 m from a waterbody. It is important to note that the habitat model considers terrestrial habitat where foraging primarily occurs and that watercourses themselves are also scored zero. It is also important to note that all scores above 1 contain suitable vegetation.
In addition to the raster layer, BHI values are associated with the reach scale Beaver Network river layer as BFI (Beaver Forage Index). Reach BFI values were obtained for two search areas, 10 m (streamside) and 40 m (riparian) from the bank edge. Both search areas extend 100 m up and downstream to account for connectivity of reaches. The mean of the top 50% of BFI values in each search area was extracted to understand the suitability of the best available habitat within a given reach.
Table 1. BVI and BHI value definitions. It is critical to note that all values above 1 are suitable for beaver. BFI and BHI Values Definition 0 Not suitable (no accessible vegetation) 1 Likely Unsuitable (unsuitable vegetation) 2 Low/Barely Suitable 3 Moderately Suitable 4 High/Suitable 5 Preferred/Highly Suitable
Beaver Habitat Index maps and summary statistics for study area Table 2. displays the summary statistics (length and %) of gross habitat category types across the watercourses of the Spey catchment (See Figure 2).
Table 2. Summary habitat mapping statistics for the Spey catchment Habitat Category Length (km) % in each category Likely Unsuitable (1) 2989.7 43.4 Low (2) 950.7 13.8 Moderate (3) 749.3 10.9 High (4) 997.3 14.5 Preferred (5) 1203.4 17.5
Beaver Dam Capacity Modelling of Spey Catchment Beaver Dam Capacity (BDC) model summary The Beaver restoration assessment tool (BRAT) was developed in North America (Macfarlane et al., 2014, 2015) to determine the capacity for river systems to support Beaver dams. The BRAT model has been further deployed in a range of different river systems to aid both Beaver recolonisation and beaver dam analogue led restoration. The BRAT model not only provides an invaluable tool for designing effective, empirically based, restoration strategies but it also indicates where Beaver dams might be constructed and therefore where they may cause potential management/conflict issues. The BRAT model structures the framework of the model around the river network itself and using a fuzzy logic approach which builds in the considerable uncertainty that is associated with beaver habitat/dammable reaches. Furthermore, it provides a range of output values to predict the dam capacity which has implications for beaver preference towards a given location.
We have therefore used the BRAT framework to develop an optimised beaver dam capacity (BDC) model for Great Britain; and although many of the datasets used are specific to GB, these could readily be adapted to enable its use globally.
The BDC model estimates the capacity of river systems to support dams at the reach-scale (ca. 150 m). The model also highlights reaches that are more likely to be dammed by beaver and estimates the number of beaver dams that could occur for a catchment at population carrying capacity. As such, this highly detailed tool would provide understanding of where dams are most likely to occur and in what densities, supporting future work on the conflicts and opportunities that might accrue from beaver reintroduction.
The model infers the density of dams that can be supported by stream reaches (111.1 m ± 52.5) across a catchment. Using low-cost and open-source datasets, the following attributes are calculated for each reach: (i) stream gradient, (ii) low (Q80) and high flow (Q2) stream power, (iii) bankfull width, (iv) stream order, and (v) the suitability of vegetation, within 10m and 40 m of the bank, for beaver dam construction. These controlling variables are combined using a sequence of inference and fuzzy inference systems which follow an expert-defined rules system that allows for the considerable uncertainty often associated with these types of complex ecological processes.
Each reach was classified for damming capacity using five categories from none, defined as no capacity for damming to pervasive where a maximum capacity of 16 – 30 dams could theoretically be constructed in a km of channel. It is important to note that the model assumes both reach and catchment population carrying capacity for beaver. Therefore, in reality the maximum number of dams indicated in a category class is unlikely to occur. A full list of BDC classifications is included in Table 3.
Table 3. BDC classifications and definitions. BDC Classification Definition None No capacity for damming Rare Max capacity for 0 – 1 dams/km Occasional Max capacity for 1 – 4 dams/km Frequent Max capacity for 5 – 15 dams/km
Pervasive Max capacity for 16 – 30dams/km
Beaver Dam Capacity Model maps and summary statistics for the study area Table 4. displays the summary statistics (length and %) of gross dam capacity category types across the watercourses of the Spey catchment (See Figure 3).
Table 4. Beaver dam capacity summary statistics for the Spey catchment Dam capacity category Length (km) % in each category None 936.0 13.6 Rare 3418.8 49.6 Occasional 1326.1 19.2 Frequent 468.1 6.8 Pervasive 741.4 10.8
Beaver habitat and dam capacity model summary The model results presented herein, illustrate that throughout the Spey catchment, including within National Park, there are extensive areas of highly suitable habitat to support beaver populations. Additionally, there are many smaller reaches, with good habitat and suitable hydrological conditions where beavers could create dams, particularly in the more lowland areas. However, model results also show the main Spey and tributaries to be too large and powerful for beavers to dam. Similarly, many of the upland areas, particularly those within the NP lack suitable habitat and are also too steep to support beaver damming. These model outputs show the spatial variability in impact that could occur if beavers returned to being widespread both within the NP and the wider Spey catchment.
Combined with other components of feasibility work being undertaken, these model results will provide a geospatial basis for informing future impacts (both positive and negative) that the reintroduction of
beavers could bring. Used strategically it is hoped that such data products can help maximise the benefits and minimise the conflicts associated with beaver.
Whilst useful, as with any model output, there are limitations and uncertainties (see Appendix 2 for use caveats) which need to be considered. These model results were ground-truthed during field visits to combine model outputs with expert interpretation to reach a conclusion on the suitability of the site will for beaver. Field based assessment will also consider the potential for beavers to bring positive impacts as well as the potential for management issues to arise and potential solutions to these.
Aspen Mapping CNP have identified interactions between beaver and aspen (Populus spp.) as a potential concern flagged by other conservation groups and so have provided maps of known areas of aspen across CNP section of the Spey catchment. Aspen is a preferred forage species for beavers (Fryxell and Doucet 1993, Nolet et al. 1994) and especially if there is low availability of food nearby beavers will travel further from the water course to obtain this. Where it grows close to suitable water bodies it would most likely have the potential to be impacted. Studies have reported that beavers typically only fell aspen in leaf (Doucet et al. 1994, Wilsson 1971). It is critical to note that aspen readily suckers in response to beaver foraging, which increases its productivity, and beavers will often then forage on regrowth. Deer and livestock will preferentially feed on broadleaf new growth, so providing grazing pressure is not intensive new growth aspen will get away. The greater concern with beaver and aspen overlap, is beaver felling of mature trees and related impacts on associated bryophyte, lichen and invertebrate communities.
If particular trees, or more likely stands of mature aspen, are flagged as of interest, tree protection management approaches are readily available. To understand where known Aspen stands may have the potential to be impacted by beaver, a 10 m buffer was applied to all Aspen points and Polygons. These data points represent small, discrete groups of aspen <0.04 ha (20 x 20 m) in extent, plus individual aspen trees. The polygons are larger stands/areas of aspen-rich woodland ≥ 0.04 ha in extent.
From Figure 8 and 9 below it is evident that a large proportion of recorded Aspen areas exist within areas considered potential beaver habitat within the Spey. Out of 533 polygons of larger Aspen stands, 340 (or 64%) fall within beaver habitat. For smaller stands represented by point data, 229 of 575 points (40%) fall within beaver habitat. It is critical to note that this is a generous overestimation of overlap with beaver habitat assuming a maximum foraging range of 100 m from water courses, far greater than that which typically occurs. This analysis is presented as a first step in identifying known aspen stands that may overlap with beaver activity; however, local management and monitoring work is likely to be required to assess the ongoing conservation importance and any associated risks.
Beavers and Fish in the Spey CNP have also identified interactions between beaver and salmonids as a potential concern. To support this feasibility project, locations of salmon and trout sampling points have been provided by CNP and the Spey Fishery Board. The sampling points provided are mapped in Figure 10, along with average density data in Figure 11 and 12. Figure 13 and 14 overlay current fish sampling points onto the beaver habitat and dam capacity layers. It is critical to note that the mapped data for fish only pertains to these datasets and additional fish data hosted by different organisations may be available. For further information on the trout and salmon data shown it is recommended contacting the Spey Fishery board.
The key benefits of beaver activity for salmonids that are commonly cited include increased habitat heterogeneity (Hägglund and Sjöberg, 1999; Smith and Mather, 2013) and quality (Pollock et al., 2003). In particular, ponds created upstream of beaver dams provide juvenile overwintering and rearing habitat (Cunjak, 1996; Needham et al., 2021), and can be a critical refuge for larger fish (Hägglund and Sjöberg, 1999; Needham et al., 2021). The beneficial response from a fisheries perspective is usually quantified in terms of increased fish abundance (Hägglund and Sjöberg, 1999; Jakober et al., 1998; Needham et al., 2021), condition and growth (Sigourney et al., 2006; but see Rabe, 1970, and Johnson et al., 1992; Needham et al., 2021), and overall productivity (Mitchell & Cunjak, 2007; Nickelson et al., 1992; Pollock et al., 2004). Conversely, the principal negative consequence of beaver activity often cited is the potential for dams to impede or delay salmonid migration, particularly for upstream moving adults during their migration to the spawning grounds (Lokteff et al., 2013; Rupp, 1955; Taylor et al., 2010). Furthermore, dams may reduce the availability of suitable spawning habitat in impounded areas, where there may be insufficient flow velocity to purge the gravels, which salmonids use for spawning and egg incubation, of the fine sediments deposited (Knudsen, 1962; Taylor et al., 2010). Malison and Halley (2020), however, found that beaver dams did not block the movement of juvenile salmonids or their ability to use upstream habitats and suggest that it is unlikely that dams negatively impact the juvenile stage of salmon or trout populations. Kemp et al. (2012) reviewed 108 studies of beaver and fish. Dams were cited as “barriers to fish movement” in 43% of papers and was the most common adverse effect discussed. However, these negative effects were speculative at best in that 78% of the studies did not support this claim with data. Further work is required to establish actual impacts of beaver dams on fish passage, but by cross referencing the BDC models with valuable salmonid habitat will help identify key areas of concern and alleviate possible impacts.
As described above, it is likely there will only be significant concerns where priority spawning grounds overlap with areas where beavers are present and there are suitable conditions for dam building. Therefore, along the main reaches of the Spey there is likely to be little concern due to there being no likelihood of damming, however, on some spawning grounds there is likely to be greater concern and need for monitoring and potential mitigation if deemed necessary. As an example of the monitoring points provided 90 out of the 181 monitoring points (49.7%) have a high (frequent or pervasive) capacity for damming if beavers were present.
Many of the monitoring points provided do fall on reaches with beaver dam capacity, meaning if beavers were present in these reaches, they may provide a monitoring opportunity or a management concern. However, with only 181 monitoring points provided it is statistically unlikely that (at least in the short term) beavers would dam directly in the vicinity of these sampling points. Therefore, to
provide opportunities to increase understanding between the impacts of beaver and fish supplementary monitoring targeted at beaver release site locations could be beneficial.
N.B. It is highly likely, as shown in the research literature for a number of sites studies (summarised in Kemp et al., (2012), that beaver activity, principally damming, will create new spawning grounds for salmonids, as cleaner and well oxygenated gravel beds are maintained. It is also possible that small areas upstream of dams accumulate sediment and potentially deteriorate in terms of quality for spawning. Thus, the balance between creation of new spawning grounds and potential negative impacts upon existing spawning grounds should be monitored. Overall, at the catchment scale, it is most likely that spawning habitat will extend and improve, as beavers establish and that salmonid population health and abundance will follow suit.
Potential Release Site Assessments Modelling outputs and site visits were made for each of the sites discussed below. Each site visit assessed and ground-truthed various site features. Methods for identifying the suitability and key habitat characteristics for beavers (both species) have been widely studied and published (including Allen 1983; Bergman et al., 2018; Dittbrenner et al., 2018; Halley et al., 2009; Hood, 2020; Macdonald et al., 1997). The main features considered included;
The initial composition and structure of the vegetation within 30 m of the water’s edge
The distribution and abundance of palatable riparian trees
The character of the riparian edge habitat
The hydrology of the water bodies available to the beavers, including flow speeds, level stability and shoreline features
Water management and where beavers may cause conflict i.e., flood banks/low-lying farmland/agricultural drainage.
Topography — gradient of land, substrate type, valley shape
Associated land-use — disturbance and land-management practices, infrastructure, water use
At each site an assessment of what beaver activities would be likely (e.g. damming or burrowing) over time and if these have a potential conflict concern were also assessed. All site survey work was undertaken in late March — early May, and involved speaking to CNP staff and local landowners associated with these sites as far as possible.
The following maps present model outputs for key sites that project partner engagement and feasibility visits have identified as being of potential interest for release. Please note no final decision has been made to release beaver at any of these sites.
In addition to model outputs, the Park Authority have provided fish (Salmon and Trout only) density monitoring points alongside mapped areas of known Aspen. For these data points represent small, discrete groups of aspen <0.04 ha (20 x 20 m) in extent, plus individual aspen trees. The polygons are larger stands/areas of aspen-rich woodland ≥ 0.04 ha in extent. These data points where near to particular sites of interest are included in maps for reference. To note these maps should be treated as displaying general data as a useful discussion starting point and further ground monitoring and refinement would be recommended going forward.
Site Mapping Summaries: Insh Marshes Overall extensive areas of suitable and highly suitable habitat around the site perimeter and more patchy vegetation within the marshes themselves which beavers will utilise. No dam capacity on the main River Spey as too large (especially when in spate), but extensive ditch and drainage systems that would support damming in some locations. Aspen presence around the reserve perimeter, but little mapped within the site itself or in the riparian zone of the main river.
Various points across the Insh Marshes reserve were assessed in collaboration with RSPB staff, especially to discuss potential sources of conflict, likely beaver behaviours and practicalities of any release.
Several points at and were assessed and most of these included highly suitable wet woodland and would be colonised by beavers from the river Spey in time, they were all Particular sensitivities of beaver damming on the were discussed. Though theoretically beavers may be able to dam this burn at low water levels, the likelihood of this should be highlighted as very low.
Given all these factors the motivation for beaver damming this stretch should be considered as very low.
Figures Redacted Figures 18 – 20. very stony with little attractive vegetation. Theoretically dammable given stream width but highly unlikely beavers would be motivated to dam and physically difficult to ever maintain.
area is a priority area for scrub removal given it is a The area itself has little tree presence but could offer attractive summer foraging. The area is lined by extensive patches of broadleaf, including aspen stands on hills nearby. It is likely as beaver population levels increase, this area would be colonised by dispersing animals, beavers on the wider marsh are also likely to retreat to this floodplain fringing woodland areas during floods. This area was discounted as a release site due to sensitivity of and perception of impacts on aspen stands. However, it would be highly likely in time and any growing population density that beaver would naturally recolonise this area, especially as beavers could be pushed into closer proximity during floods. Sensitive mature aspen stands and lichen assemblage of conservation value are generally quite far back and uphill of the floodplain, though of significant distance to both any proposed release sites and extent of higher flood levels, proactive monitoring and consideration of beaver deterrent fencing should field signs approach this area would be recommended. Planting a buffer of willow could also be used in targeted areas to reduce motivation to forage on more valuable areas of woodland. A stock fence is currently present along much of the fringing woodland. It was noted that the dimensions would not prevent beaver access, with some concerns that a risk may be posed to smaller animals becoming stuck.
Figure Redacted Figure 21. Insh Marshes overview This area is fringed by higher banks and expansive broadleaf assemblage including aspen and is likely to become attractive as population density increases and/or during periods of expansive flooding of the Spey.
Figures Redacted Figures 22 and 23. Insh Marshes, noting vegetation diversity likely rich summer feeding for beavers and expansive fringing broadleaf woodland likely to become more accessible and attractive during peak floods. Mature aspen stands are present but generally set well-back from floodplain, though beavers could display selective foraging in time. Reactive management plans including fencing and sacrificial willow planting would be prudent strategies.
Onsite discussions with CNP and RSPB staff have highlighted a monitoring schedule within such sensitive areas will be critical, with an agreed flowchart of mitigation steps dependent on what activities occur.
Burns within such woodlands are typically steep and rocky, so therefore would be difficult for beavers to maintain dams, would be a lot of effort for beavers to maintain dams / deep water here. Monitoring efforts should focus round the burns.
This is well vegetated with extensive broadleaf and wet woodland, it is connected to the river Spey through a long range of wooded ditches fringing the marsh. These ditches appear to be deep, therefore damming is less likely, but beavers are likely to increase open water in this area through canal digging and potential damming of smaller burns. Banks are readily burrowable. Overall, this would be a highly suitable release site and likely to be fairly self-contained. Beaver activity could be viewed and has the potential to increase the diversity, complexity and ecological interest in this area.
The main potential issue would be if beavers utilised the nearby of Further discussion and investigation to determine if beaver activity could impact on water tree foraging. levels around
Figure Redacted Figure 24.
Figures Redacted Figures 25 and 26. is also well wooded and supported with diverse understory vegetation. Damming along these water courses is highly unlikely given depth of water, however an adjoining burn to the right could readily be dammed and may have some impacts on Dams in this burn could be mitigated.
Figure Redacted Figure 27. One of the main drains running through RSPB Insh Marshes, such habitat scores low for suitability and damming capacity unlikely due to depth. Beavers would readily utilise such ditches for access to more attractive habitat and foraging resources and for wider catchment dispersal, considered positive for genetic flow.
The lower section of the was assessed. In general, this is a well-wooded water course, but very rocky and shallow, with periods of high energy spates. Though some sections appear on modelling which are theoretically dammable, in reality the likelihood of beaver maintaining dams is unlikely and would be seasonally flushed out. The shoreline is very rocky and in general seems unattractive to beaver colonisation and not considered as a suitable release site. At high population density, dispersing individuals may explore and utilise this area in seeking any suitable habitat upstream. In general, this would be considered as a low conflict area.
and wet woodland area This is a pool- ditch system dominated by mixed age willow. Deer impacts are evident, and a revision of deer management is suggested but willow is getting away in inaccessible areas. Damming and
burrowing would not be any issue here and RSPB would welcome an increased complexity generated by beaver activity. The though beavers would readily use the wider area and have access to forage and shelter creation opportunities without concern. The river is very accessible and immediately provides good stretches of highly suitable habitat.
Figures Redacted Figures 28 – 31. Wet woodland associated with the and offering highly suitable habitat and shelter opportunities. Banks are highly suitable to burrow and shelter construction. This area does regularly see annual flooding events though beavers would be very able to be mobile with water levels and seek shelter and foraging opportunities on higher fringing banks and woodland.
Figures Redacted Figures 32 and 33. offers very attractive habitat and it could be likely any released beavers reside in This area and forage in the fen behind. is accessible, with willow dominated tree coverage and deep friable banks for easy shelter construction.
on the reserve. The majority of This area of the Insh marshes offers an area of the shoreline is supported by stretches of highly suitable habitat, including large sections of wet willow fen. Emergent and aquatic vegetation is also high in this area especially offering plenty of summer foraging opportunities. Given the bank profile gradient, burrowing for shelter opportunities may be limited, however lodge construction would be entirely possible. Beaver activities may also see extensive canal networks being constructed should beaver reside in this area. Highly suitable and attractive habitat is present in significant sections on the main River Spey below. Proximity to and being linked by extensive willow woodland, makes this very accessible but also likely that any beaver released onto the are likely to concentrate activities in this area and less likely to be attracted to woodland associated with This has been flagged for mature woodland, aspen, bryophyte and lichen interests, but this so not likely to be vulnerable to beaver foraging with any impacts most likely concentrated in the less steep perimeter area of the site. On site discussions with CNPA, Beaver Trust and RSPB staff have determined that a long-term monitoring programme for any beaver impacts would be possible in this area which would trigger a reactive implementation of a mitigation strategy.
Figures Redacted Figures 34 and 35. Looking into and entirely passable for beavers. Figure Redacted
areas from Stock fencing is constructed from posts and horizontal wire only
Figure 36. Proximity of loch to River Spey fringes to the right. Beavers highly likely to release is recommended. access both feeding resources and may be initially attracted to this river section, though a Figure Redacted Figure 37. River Spey below — low conflict area with good sections of high quality habitat.
is surrounded with a wide margin of wet woodland. Associated reed beds, aquatic and semi-aquatic vegetation appear extensive and diverse, lined with broadleaf and would provide
extensive foraging opportunities year-round. The shoreline has multiple bays and complexities and though generally low in gradient, shelter building opportunities would not be an issue. Water levels appear fairly stable but if floods occur beavers would have fringing shoreline to move into without restrictions. Mapping demonstrates an excellent expanse of highly suitable habitat both around the loch and the neighbouring riparian zone of the main channel. High modelled dam capacity on both inflow and outflow, but main the Spey are too large to be dammed. Any damming would serve to increase wetland habitat and complexity of this site, with additional biodiversity benefits highly likely. Surrounding marsh/grassland could readily contain a network of beaver dug canals, again increasing site complexity and areas of open water. No mapped Aspen stands in the riparian zone of either or immediate riparian zone of Spey. No fish density data sampling points provided. In general, the potential for conflict at this site appears low with surrounding land-use deciduous woodland with some tracks which are all located away from the itself, therefore it seems unlikely burrowing, damming or tree felling are likely to be an issue.
Figure Redacted Figure 38. Beaver habitat mapping for. and surrounding area.
Figure Redacted Figure 39. Beaver dam capacity mapping for and surrounding area.
Figure Redacted Figure 40. Beaver dam capacity mapping alongside known areas of Aspen and fish monitoring points for and surrounding area.
Figure Redacted Figure 41. Overview of with complex shoreline including multiple bays, good broadleaf coverage and extensive wetland with patches of wet woodland