TECHNICAL APPENDIX A7.3

BEINNEUN WINDFARM WATER VOLE SURVEY METHODS AND RESULTS

Beinneun Wind Farm: survey of water vole habitat and signs

Commissioned Report to Arcus Renewable Energy Consulting Ltd

November 2010

Denny, R., Scott, R. & Watt, J. 2010. Beinneun Wind Farm: survey of water vole habitat and signs. Commissioned Report to Arcus Renewable Energy Consulting Ltd. November 2010

Waterside Ecology Druimindarroch Arisaig Inverness-shire PH39 4NR T: 01687 450298 M: 07788717605 jon@watersideecology.co.uk

www.watersideecology.co.uk

Beinneun Wind Farm: survey of water vole habitat and signs 1 Background 1.1 National and local status

The water vole Arvicola terrestris is one of Britain's most threatened mammal species. Over the last fifty years its population is estimated to have declined by 94% (Strachan & Jefferies, 1993; Strachan, Strachan & Jefferies, 2000), one of the most rapid and serious declines of any UK mammal. Habitat loss and degradation, fluctuations in water levels and pollution have all contributed to this decline but it has been exacerbated by the spread of the American mink Neovison vison, an introduced and very efficient generalist predator (Strachan 1998). Mink were brought to fur farms in the UK in the 1920s and 1930s and following escapes and intentional releases they began to establish themselves in the wild in the late 1950's. Mink are now widespread throughout Britain with the exception of the far north west of Scotland (Green & Green, 1997). Once an American mink has colonised a waterway its impact on water voles is usually catastrophic leading to localised water vole extinction as well as fragmentation of remaining populations, threatening their long-term viability. The far north west of Scotland, where mink are still absent, is an important refuge for water voles. Although the Atlas of Mammals in Britain (Arnold 1993) shows water voles to be largely absent from most of the Scottish Highlands recent studies have shown them to be far more widespread than previously thought (Woodroffe 2000). Gaps in known distribution partly reflect the fact that water voles are still under recorded in upland areas. Upland populations tend to be localised and small reflecting the naturally patchy distribution of suitable habitat. Mink tend to be scarce in open moorland and mountainous terrain, preferring the greater cover and abundance of prey that is found in the lower lying parts of river systems (Raynor 2002), upland areas are therefore also important refuges for water voles from mink predation. A search of the National Biodiversity Network (NBN) database found water vole records in and around the current survey area. The survey area is in the range of the American mink on the west coast of Scotland. A search of the NBN database revealed records for the survey area between 1989 and 1994 and more recent records in the broader locality.

1.2.1 Legislation and conservation The water vole received legal protection in 1998 through its inclusion on Schedule 5 of the Wildlife & Countryside Act 1981 (as amended), Section 9(4). This provided protection for the water vole’s places of shelter or protection, making it an offence to intentionally or recklessly damage, destroy or obstruct access to any structure or place that water voles use for shelter or protection or to disturb water voles while they are using such a place. Water voles themselves were not protected until the 6 April 2008 when the legislation was changed to give the water vole full protection under the Wildlife and Countryside act. It is now illegal to intentionally or recklessly kill, injure or take a water vole from the wild. The water vole is listed under the UK Biodiversity Action Plan as a ‘Priority Species’ requiring the implementation of a Species Action Plan dedicated to its survival (Biodiversity Steering Group, 1995).

1.3 Ecology

The water vole is found along slow flowing (low gradient) waterway edges in a variety of habitats from upland streams to wide rivers and agricultural ditches (Lambin et al 2004; Strachan & Moorhouse 2006). Water voles are almost wholly vegetarian, feeding on a wide range of plants. They favour riparian habitats with luxurious bank-side vegetation, particularly grasses and sedges, to provide food and cover from predators. Water voles create extensive systems of burrows with interconnecting tunnels and entrances both above and below the water surface. Steep banks of 35 degrees or more allow burrowing and, importantly, provide refuge during flood events. Rocky banks are avoided due to the difficulty of excavation. Adult male water voles occupy territories of between 60 and 300 metres and adult female water voles occupy territories of between 30 and 150 metres depending on population density, time of year and habitat quality. The larger range sizes occur where population density is low and habitat is poor.

Water voles leave a number of distinctive field signs, useful for their study. They make runways in the vegetation, extensive burrow systems, leave piles of feeding remain (short lengths of vegetation 5-10 cm long) and most significantly mark their home ranges with faecal latrines.

2 Survey aims and methods

The aims of the water vole survey were to:

1. Establish presence/absence of water voles along watercourses in the survey area. 2. Assess the habitat quality for water voles along the same watercourses.

The survey included all watercourses with a gentle gradient (where the 10m contour lines are greater than 4 mm apart on a 1:25000 map) within the survey area and some just outside it (Figures 1-5). The banks of each watercourse were surveyed and observations of bank-side vegetation, habitat structure and signs of water vole activity noted. During surveying, copies of 1: 10,000 maps were used in conjunction with a GPS to accurately establish locations. Waterways in the survey area were divided into forty sections reflecting changes in bank or vegetation structure (Maps 1 -5). Each survey section was ranked in one of three categories:

O = Optimal water vole habitat

SO = Sub-optimal water vole habitat

US = Unsuitable water vole habitat

The attributes of each habitat category are taken from Lawton and Woodroffe (1991) and the UK Water Vole Steering Group Action Plan (1997) as follows:

Slow-flowing watercourse, less than 5m wide and about 1m deep, without extreme fluctuations in water level. Shore type is predominantly earth with a stepped or steep incline (35 degrees or more) into which the voles can burrow and create nest chambers above the water table. Water voles can also occur on low banks, such as along ditches and drains where there is no fluctuation in water levels. There should be an abundance of bankside vegetation (70% or more of grasses) which shows a high foliage height diversity.

Optimal habitat

Slow flowing watercourse with adequate covering of vegetation and the potential for burrowing in banks.

Sub-optimal habitat

Unsuitable sites have low potential for cover or food, such as banks heavily grazed or trampled by livestock. The channel may be flat-sided, providing no refuge against fluctuating water levels or dry. Sites that are excessively shaded, rocky or engineered are also less favoured, because this has a limiting effect on growth of suitable bankside vegetation. Rocky or engineered banks may also prevent burrowing.

Unsuitable habitat

3 Results and discussion 3.1 Water vole signs

Signs of water vole occupancy were identified at 12 sites during this survey and a further 2 sites just outside the survey area. These 12 sites can be divided into six discrete areas of water vole activity, two of which had signs of current occupancy. Details and location of water vole signs recorded are shown in table 1 and maps 1 to 5. 1. The highest density of water vole signs was found in Coire nam Brach . Signs were found along the length of the low gradient sections of this burn. Water vole sites 1-8 (Table 1) indicate three core burrow areas at sites 2 (10 holes), 4 (20+ holes) and 5 (60+ holes). Latrines or recent droppings indicating current occupancy were found at sites 2 and 5. Sites 3, 6, 7 and 8 had less than 4 old burrows and no signs of recent activity. Each of these sites was within 200m of the next site and as this is within the home range of an adult water vole this area is considered to be one currently occupied water vole colony or habitat patch.

2. Water vole signs were found at the top of Caochan Riabhach (site 9) where four burrows were identified but no signs of current occupancy. 3. Signs of previous occupancy were found at site 10 between Carn Dearg and Clach Criche. Ten burrows were found here but although some holes looked recently used no obvious signs of current activity by water voles were found. This burn frequently flowed underground and latrines are often out of sight below ground in this type of habitat. It is possible that this site was currently occupied but signs were less obvious due to the terrain. 4. Two burrows were found at site 11 in Coire Daingean with no other signs of recent occupancy. 5. Four burrows were found at site 12 at the top of the western limb of the Allt Bealach Odhar with no other signs of recent occupancy. 6. An area of 39+ burrows and 8 latrines was found just outside the survey area on a small tributary into the west side of Allt Garbh-Dhoire. No very fresh droppings were found but latrines looked less than a few weeks old. Heavy rain had fallen the day before survey work was undertaken and it is possible that some signs indicating current occupancy such as droppings and feeding remains had been washed away. Water vole burrows can persist for many years in upland areas and evidence of old burrow systems can often be found in areas previously occupied by water voles (Aars et al 2001). Sites of old burrows identified during this survey but with no signs of current occupation indicate areas previously occupied by water vole and given the highly dispersing nature of water voles are likely to be occupied again in the future. Sites with only 1 or 2 burrows may indicate areas of more temporary refuge in a less suitable habitat patch while animals are dispersing to more suitable areas.

3.2 Habitat availability

Habitats in each section are described in Table 2 and locations of each habitat section are shown in Maps 1 to 5. The survey area consisted of long stretches of unsuitable habitat (either too steep, rocky or with sparse vegetation cover) with small (approx 100 m to 500 m) patches of sub-optimal habitat in between. All sections of suitable habitat more than 200 m in length showed signs of water vole occupancy. No sections of suitable habitat less than 100 m long showed signs of previous occupancy. Some sections of suitable habitat between 100 and 200 m in length showed signs of occupancy but these tended to be of between 1 and 4 old holes indicating they may be used more as temporary refuges rather than breeding colonies. This distribution of habitat and occupancy is fairly typical of upland areas where patches of suitable habitat and water vole colonies tend to be small, scattered and isolated from each other by long sections of unsuitable habitat. Only a fraction of suitable habitat patches tend to be occupied in any one year. Colonies typically consist of only 1 or 2 adults (Aars et al 2001). These small colonies are small sub-populations of the over all water vole population in upland areas. Such sub-populations are very vulnerable to extinction but can be preserved through the ability of individuals to disperse long distances from other sub-populations resulting in the overall population remaining relatively stable.

Water voles are effective dispersers, moving an average distance of 3.5 km to find a mate and appropriate habitat. Longer distances of up to 23.9 km have been recorded Lambin et al in prep). Water voles will keep dispersing until they reach a patch of suitable habitat that is occupied by a potential mate or will remain in a suitable but otherwise unoccupied patch for an average of 10 days before they move on again until they find a suitable habitat patch with a mate (Lambin et al 2004, Lambin pers comm). The movement of individuals between areas of suitable habitat (usually via unsuitable habitat) can not only boost existing population numbers but can result in re-colonisation of new or previously occupied patches of suitable habitat. Over time, loss of unoccupied habitat may be as important as loss of occupied habitat, since vacant habitats may become occupied over time, maintaining the overall stability of the population. Small and sub-optimal patches of habitat in otherwise unsuitable areas are also important in providing stepping-stones of foraging and temporary refuge during dispersal to areas with more suitable habitat. Loss of habitat patches may effect the wider water vole population by increasing isolation and therefore raising extinction risk.

4 References Aars, J., Lambin, X., Denny, R. & Griffin, C. (2001). Water vole in the Scottsih uplands: distribution patterns of disturbed and pristine populations ahead and behind the American mink invasion front. Animal Conservation 4, 187-194. Arnold, H. R. (1993). Atlas of Mammals in Britain, ITE, London. Biodiversity Steering Group 1995. Biodiversity: The UK Steering Group Report. Vol. 2. Action Plans. HMSO, London. Green, R. & Green, J. (1997). Otter survey of Scotland, 1991-1997. London: The Vincent Wildlife Trust Lambin, X., Aars, J., Piertney, S. B. & Telfer, S. (2004). Inferring pattern and process in small mammal met populations: insights from ecological and genetic data. In Ecology, Genetics and Evolution of Metapopulations. (ed. I. Hanski & M. Eilpin). pp. 515-450. Elsevier, Inc. Lambin, X., Le Bouille, D., Oliver, M.K., Sutherland, C. Tedesco, E & Douglas, A. In prep. High connectivity despite high fragmentation: iterated dispersal in a vertebrate metapopulation. Macdonald, D & Baker, S. (2005). The State of Britain’s Mammals 2005. WILDCRU Raynor, R (2002). Conserving Scotland’s Water Voles. Scottish Natural Heritage. Strachan, R. & Jefferies, D.J. (1993). The water vole Arvicola terrestris in Britain 1989-1990: its distribution and changing status. London: The Vincent Wildlife Trust. Strachan, R. & Moorhouse, T. (2006). Water Vole Conservation Handbook. Wildlife Conservation Research Unit, Great Britain. Strachan, C., Strachan, R. & Jefferies, D. (2000). Preliminary report on the changes in the water vole population of Britain as shown by the national survey of 1989-1990 and 1996-1998. The Vincent Wildlife Trust: London. Woodroffe, G. (2000). The water vole. The Mammal Society

Table 1. Beinneun Wind Farm, water vole signs, October 2010.

Site Section NGR start signs NGR end signs Photo Latrines

(n) Burrows (n) Runs Feeding remains Notes

1 C-D NH 2140 0609 NH 2137 0608 1 1 old Y Signs in Juncus effusus bed, both sides of burn. Whole area recently washed over by spate.

2 C-D NH 2130 0611 NH 2124 0616 2,3 3 10 Y Juncus effusus Signs in Juncus bed at confluence of 2 burns and upstream

3 C-E NH 2127 0593 NH 2127 0595 none 0 3 Burn with steep peaty banks, Potomogeton polygonifolius in water

4 C-E NH 2136 0576 NH 2135 0571 none 0 +20 Y Recent flood debris above burrow level. P. polygonifolius and Carex rostrata in water. Very large deer wallow nearby.

5 E-F NH 2129 0566 NH 2134 0559 none I old, few fresh

droppings

+60 Y J. effusus, M. caerula,

Deschampsia cespitosa

Burn partially disappears below surface under Molinia and Juncus

6 E-G NH 2117 0562 NH 2117 0562 none 0 4 Y Few runs

7 E-G NH 2109 0557 NH 2109 0557 4 0 1 Level stretch of burn with peaty substrate and P. polygonifolius, Utricularia sp., Eriophorum angustifolium in pool.

8 E-G NH 2100 0551 NH 2100 0551 none 0 1 Y Peaty burn with Carex rostrata, Juncus bullosa

9 H-I NH 2054 0528 NH 2057 0528 none 0 4 Peaty burn with Eriophorum angustifolium, Juncus bullosa, Potomegeton polygonifolius.

10 NH 2280 0673 NH 2281 0649 1655/1706

0 10 Some holes look recently used but no other signs found. Burn mostly flowing under peat with Nardus stricta.

11 NH 2326 0593 NH 2326 0593 none 0 2 1 hole looks recently used but only field vole signs found, generally fast flowing burn but peaty banks with slow flowing meander and pool at this point

12 P-Q NH 2230 0714 NH 2230 0714 1253 0 4 prob Field vole signs but no other water vole signs on small peaty terrace with limited cover.

Outside wind farm area 13 N/A NH 2085 0626 NH 2079 0625 8 old 0 39 Y Field voles currently using burrows. No fresh water vole

signs but many signs of activity possibly a few weeks old. Droppings also at NH 2083 0625

Table 2. Water vole habitat quality

Section Map Upstream Downstream Quality Habitat Notes Aa-A 1 NH 2114 0622 NH 2073 0673 US R A-B 1&2 NH 2155 0616 NH 2114 0622 US R Fast and rocky A-C 1&2 NH 2124 0607 2114 0622 SO R C-D 2 NH 2150 0605 NH 2124 0607 SO R C-E 2 NH 2130 0565 NH 2124 0607 SO R E-F 2 NH 2136 0558 NH 2130 0565 SO R/B E-G 2 NH 2100 0548 NH 2130 0565 SO R/B H-1 2 NH 2071 0502 NH 2051 0530 SO B/R J-K 2 NH 2170 0539 NH 2170 0539 SO R/B L-M 2 NH 2231 0573 NH 2215 0582 SO L/B N-O 3 NH 2243 0536 NH 2243 0536 SO B/R

P-Q 4 NH 2230 0714 NH 2228 0717 SO R Small peaty terrace. Deer grass, heather, bog asphodel, sparse purple moor grass

R-T 4 & 5 NH 2352 0744 NH 2303 0774 US R Rocky with very small peaty meanders

R-S 4 & 5 NH 2323 0765 NH 2303 0774 SO/US R

Wet heath, short, sparse vegetation cover, lower terrace has more purple moor grass cover and underground sections. Upstream is damp with exposed peat hag

T-U 5 NH 2352 0741 NH 2352 0744 US R Grassier but undercut inaccessible peat banks. Too fast

U-V 5 NH 2883

0723/NH 2883 0723

2332 0741 US R

V-Y 5 NH 2435 0756 2417 0746 US R Peat banks upstream but remains too fast with banks exposed and sparse vegetation cover

Z 5 NH 2462 0756 US L Vegetation cover too sparse and shrubby

Z-Ab 5 NH 2464 0754 NH 2469 0721 US R Stony or vegetation too sparse cover, lower down exposed peat hags.

X-Ac 5 NH 2429 0721 NH 2395 0722 US R Peat hags with little in way of banks or steep and fast

Ac-W 5 NH 2395 0722 NH 2391 0723 SO R/UG Short underground section with reasonable habitat/peat banks and cover. Field vole latrine

V-W 5 NH 2388 0723 NH 2383 0723 SO R Grass and underground stretch providing acceptable cover with burrowable banks. But short section.

U-Ad 5 NH 2326 0708 NH 2354 0732 US R Fast flowing, shrubby, stony Ad 5 NH 2326 0708 US L Stony, shrubby banks Ae-Af 4 NH 2304 0692 NH 2321 0704 US R Exposed peaty or stony banks Ag 4 NH 2290 0700 US L Stony, shrubby banks

Ah-Ai 4 NH 2288 0692 NH 2283 0677 SO/US R Very marginal. Reasonable sedge cover in places and good peat banks. Peat hags and stony lower down.

Ai-Aj 4 NH 2283 0677 NH 2280 0673 US R Exposed peat hags. Very sparse vegetation

Aj-Ak 4 NH 2280 0673 NH 2279 0647 SO R Burn mostly flowing underground giving cover, grass and heather.

Aj-Al 4 NH 2259 0679 NH 2272 0665 US R Sparse vegetation with exposed peat below loch. Stony

Ak-Am 3 NH 2279 0647 NH 2317 0600 US R Stony

Am-An 3 NH 2317 0600 2328 0593 SO R Fast but peat banks. Slower at meander and pools. Field vole signs

Ao-Ap 3 NH 2336 0640 NH 2364 0611 US R Fast flowing and rocky

Table 2 contd. Water vole habitat quality

Section Map Upstream Downstream Quality Habitat Notes

Ap-Aq 3 NH 2364 0611 NH 2363 0629 US/SO R Western limb has very low flow, with a short grassy underground section with some limited potential as habitat

Outside survey area

1 NH 2079 0623 NH 2099 0647 SO R Heather, sparse purple moor grass, deer grass, bog asphodel. Currently

River Loyne: NH 2122 0857 NH2120 0850 SO R

Small burn into river. Field vole signs. Flood prone but could hold burrows with good veg cover. By river shaded by trees and less of a bank . Flooding likely to limit habitat

NH 2111 0854 NH 2125 0860 US R River Loyne. Plenty field vole latrines. Very prone to flooding.

NH 2090 0850 NH 2095 0850 SO Small burn. Fast flowing, flood prone, unstable sandy banks. Field vole signs.

NH 2089 0849 NH 2111 0854 US R River Loyne. Stony and low gradient banks. Flood prone.

NH 2089 0832 NH 2111 0854 SO R Molinia tussock and soft rush. Flood prone likely to limit habitat. Field vole signs

Quality: US = unsuitable, SO = sub-optimal, O = optimal

Habitat: B = bog, R = running water, L = loch, UG = underground flow.

Additional habitat data are provided in accompanying spreadsheets.

Habitat survey maps

Map 1

Map 2

Map 3

Map 4

Map 5