beta

You're viewing our new website - find out more

Publication - Consultation Paper

Beavers in Scotland: consultation on the strategic environmental assessment

Published: 12 Dec 2017

A consultation on the policy to reintroduce beavers to Scotland and the strategic environmental assessment of this policy.

170 page PDF

3.0MB

170 page PDF

3.0MB

Contents
Beavers in Scotland: consultation on the strategic environmental assessment
4.7 Beavers and Birds

170 page PDF

3.0MB

4.7 Beavers and Birds

4.7.1 How beaver activity affects birds

The main mechanism for beavers influencing avian biodiversity is the increase in wetland areas available for nesting and feeding. Overall, international studies show that beavers increase avian biodiversity in riparian areas by increasing the amount of slow-moving water and well-vegetated wetland habitat. Groups that respond best to increases in these habitats are waterfowl, herons and kingfishers. A summary (see Table 4.7.1) of the positive and negative effects of beaver activity on bird species is presented at the end of this section.

The aquatic characteristics of beaver ponds, such as large shallow water areas with gradual edges, may be particularly important for a variety of species of waterfowl. The gradual edges of beaver ponds may be a key driver of high bird biodiversity, as they provide a structurally complex habitat that may improve nest concealment, reduce predation, increase food production and provide a diverse range of ecological niches. The interspersion of different vegetation types seems to be a key component of this habitat, which can provide cover for waterfowl in particular.

The habitats created by beavers also provide a more abundant food supply for birds. Beaver impoundments tend to contain an abundant aquatic assemblage including a diverse range of macro-invertebrates which are an excellent food source for ducks. An increased abundance and diversity of fish and amphibians within beaver impoundments provides food for species such as grey heron Ardea cinerea and kingfisher Alcedo atthis.

The ponds created by beaver dams often flood and kill trees in the riparian zone. This attracts woodpeckers, as standing dead wood is an important nesting and feeding habitat for them. Woodpecker holes are also used by a range of secondary cavity-nesting species. Dead trees and snags are an important site for foraging and nesting raptors, which may also prey on beavers.

Beaver meadows support diverse grassland vegetation, which promotes bird biodiversity and may be an essential source of habitat for grassland birds on a landscape scale. In Canada, one study found that beaver meadows had higher levels of songbird biodiversity than all the adjacent riparian habitats.

Beavers may also encourage bird abundance in less obvious ways. Where ponds are covered with ice and snow for much of the winter, beaver physical activity causes the ice to melt earlier in the spring. This can bring benefits to wildfowl, for example beaver ponds have been shown to give Canada geese Branta canadensis access to an important habitat for an extended period.

Table 4.7.1: Summary of potential interactions between beavers and birds

Activity

Mechanism

Positive effects

Negative effects

Notes

Felling

Change in riparian woodland: Opening of woodland canopy and increased patchiness

  • A more open woodland canopy improves foraging habitat for small insectivorous birds, e.g. tree pipit
  • Overall positive effects on diversity at landscape scale since beaver activity markedly increases habitat heterogeneity and patchiness through the creation of canopy gaps, etc.

Felling

Change in riparian woodland: Change in age classes of trees

  • Beaver-coppiced riparian woodland is likely to benefit many small insectivorous species, e.g. warblers
  • Fewer large trees may adversely affect some groups of birds, e.g. woodpeckers

Felling

Change in riparian woodland: Amount/diversity of fallen dead wood on woodland floor

  • Uncertain, but may be beneficial impacts on invertebrate and other prey species

Felling and constructions

Changes in amount/diversity of woody material in watercourses

  • Uncertain, but may be beneficial impacts on prey species, e.g. fish for mergansers, goosanders, etc.

Dams/pond creation

Change from lotic to lentic habitat

  • Overall positive effects on diversity at landscape scale since beaver activity markedly increases habitat heterogeneity and patchiness, with lentic and associated wetland habitat interspersed with lotic habitat
  • The creation of pond habitat will boost prey abundance for many bird species
  • The creation of habitat which may benefit invasive non-native species such as mandarin duck

Dams/pond creation

Change in hydrological processes on riparian and downstream habitat

  • The creation of new riparian wetland will boost prey abundance for many bird species

Dams/pond creation

Changes in water quality downstream

  • Uncertain, but may be beneficial impacts on prey species, e.g. fish

Dams/pond creation

Change in standing dead wood resulting from inundation of trees

  • May provide increased nesting and feeding opportunities for woodpeckers, nuthatches and raptors

Dams/pond creation

Longer term successional changes after dam abandonment, e.g. beaver meadows

  • Evidence from North America of an increase in diversity and number of grassland bird species on beaver meadows

Dams/pond creation

Impacts on movement of species

  • Beaver dams may sometimes have adverse impacts on migratory fish species, with consequent localised impacts on piscivorous birds

See Annex 1, Table 3.14 for effects of beavers on fish

Other constructions

Creation of lodges, burrows, canals, etc.

  • Lodges provide additional secure nesting and resting places for a variety of bird species
  • Invasive non-native Canada geese may utilise these structures

Other

  • Beavers (especially juveniles) may be a prey species for predators, such as white-tailed eagle

Indirect habitat creation/restoration initiatives as result of beaver presence

Beaver used to promote opportunities for riparian and freshwater habitat creation/restoration

  • Presence of beavers may act as an incentive for greater investment, management and monitoring. This could those related to the restoration and management of riparian woodland and wetlands, which would benefit a range of bird species

4.7.2 Distribution of birds in the beaver policy area

The following section concentrates on those bird species of conservation importance that are likely to overlap with core beaver woodland and as such maybe positively or negatively affected by beaver activity in the policy area.

4.7.2.1 Bird species of conservation importance

To determine whether the activity of beavers on bird species is significant in the context of this Strategic Environmental Assessment, the assessment of impacts (positive and negative) has focussed on those species for which beaver activity may affect directly or indirectly (as discussed above), which are considered as having conservation importance and as such are afforded European or national protection wherever they occur.

Table 4.7.2 below therefore identifies those bird species of conservation importance that utilise 'potential beaver core woodland' (as described in section 4.2. of this report) and are found within the beaver policy areas.

Table 4.7.2: Summary of bird species of conservation importance within the policy area that overlap with potential beaver core woodland

Bird species (B = breeding, NB = Non-breeding)

SPA

SSSI

Black throated diver (B)

Rannoch Lochs SPA
Knapdale Lochs SPA

Rannoch Lochs SSSI
Knapdale Lochs SPA

Scottish crossbill (B)

Ballochbuie SPA
Cairngorms SPA

Creag Clunie and the Lion's Face SSSI

Greylag goose ( NB)

South Tayside Goose Roosts SPA (& Ramsar)
Loch of Lintrathen SPA (& Ramsar)
Loch of Kinnordy SPA (& Ramsar)
Firth of Tay and Eden Estuary SPA (& Ramsar)
Montrose Basin Ramsar (Dun's dish component only)

Carsebreak and Rhynd Lochs SSSI
Loch of Lintrathen SSSI
Loch of Kinnordy SSSI
Loch Leven SSSI
Inner Tay Estuary SSSI
Hare Myre, Monk Myre and Stormont Loch SSSI
Lochs Clunie and Marlee SSSI
Meikleour Area SSSI
Drummond Lochs SSSI
Lochs Clunie and Marlee SSSI
Lochs of Butterstone, Craiglush and Lowes SSSI

Pink footed goose ( NB)

Firth of Tay and Eden Estuary SPA (& Ramsar)
Loch Leven SPA (& Ramsar)
Loch of Kinnordy SPA (& Ramsar)
South Tayside Goose Roosts SPA (& Ramsar)
Montrose Basin Ramsar (Dun's dish component only)

Inner Tay Estuary SSSI
Loch Leven SSSI
Loch of Kinnordy SSSI
Carsebreak and Rhynd Lochs SSSI
Dupplin Lakes SSSI

Whooper swan ( NB)

Loch Leven SPA

Loch Leven SSSI

Breeding bird assemblage

Black Wood of Rannoch SSSI
Cairngorms SSSI
Dunalastair Reservoir SSSI
Dun's Dish SSSI
Dupplin Lakes SSSI
Eastern Cairngorms SSSI
Forest of Clunie SSSI
Inner Tay Estuary SSSI
Knapdale Woods SSSI
Lindores Loch SSSI
Loch Leven SSSI
Loch of Kinnordy SSSI
Lochs of Butterstone, Craiglush and Lowes SSSI
Moine Mhor SSSI
Shingle Islands SSSI

4.7.3 Assessment of likely effects on bird species of conservation importance in the policy area

Each of the bird species identified in Table 4.7.2 above are discussed in turn below in the context of those effects (positive or negative) that have been identified as a result of beaver activity. Where this relates to a species included in the Habitats Regulation Appraisal of the policy, a summary of the advice from SNH, provided to inform an appropriate assessment ( AA) of the policy with respect to SPA sites (see Annex 2 for the full advice) has been used (referred to hereafter as ' SNH HRA advice'). For the purpose of this assessment, the concluding points of the SNH HRA advice have been replicated where appropriate for each species. Assessment of other bird species (i.e. SSSI notified features), has been made in the context of the SNH HRA advice in combination with knowledge of the individual sites and their condition. For completeness, Ramsar sites have also been included, assessment of which is considered analogous with the SPA. Where mitigation or monitoring maybe appropriate, this has been identified in the narrative. Further discussion relating to the management of beavers including mitigation and monitoring options is provided in section 5 and 7 respectively.

For species and habitats of conservation interest in the wider countryside there will be an ongoing need to assess data derived from general surveillance and monitoring activities that are already in place, and intervene with management if and when necessary. This will be informed by a more strategic approach to management being developed in due course.

Beaver opportunities

As summarised above, beaver activity has the potential to create positive effects. More than this, the presence of beavers may act as an incentive for greater investment, management and monitoring. This could those related to the restoration and management of riparian woodland and wetlands, which would benefit a range of bird species.

4.7.3.1 Consideration of potential positive effects on bird species of conservation importance

The impact of beaver activity on the bird species discussed below is considered to be either positive or neutral. Where there is considered to be a negative effect or the potential for a negative effect, these are discussed in the following section, see 4.7.3.2. A more general discussion is provided first, followed by a more species / site-based assessment.

Those bird species that utilise woodland for breeding foraging and shelter may benefit from beaver felling activity. These can be summarised as:

  • A more open woodland canopy improves foraging habitat for small insectivorous birds, e.g. tree pipit.
  • Beaver-coppiced riparian woodland is likely to benefit many small insectivorous species, e.g. warblers.
  • Overall positive effects on diversity at landscape scale since beaver activity markedly increases habitat heterogeneity and patchiness through the creation of canopy gaps, etc.
  • Standing deadwood may provide increased nesting and feeding opportunities for woodpeckers, nuthatches and raptors.

Those bird species that utilise standing freshwater and wetland habitats for breeding and foraging may benefit from beaver damming activity and herbivory. These can be summarised as:

  • The creation of pond habitat will boost prey abundance for many bird species.
  • The creation of new riparian wetland will boost prey abundance for many bird species.
  • Evidence from North America of an increase in diversity and number of grassland bird species on beaver meadows
  • Overall positive effects on diversity at landscape scale since beaver activity markedly increases habitat heterogeneity and patchiness, with lentic and associated wetland habitat interspersed with lotic habitat.
  • Lodges provide additional secure nesting and resting places for a variety of bird species.

Black Throated Diver

Scotland's fresh water environments are diverse, extensive, and typically have a high water quality. It's therefore no surprise that they support a wide range of bird species. The shores of nutrient-poor upland lochs are breeding sites for black-throated diver.

Within Britain, which is the extreme oceanic edge of its range, it is restricted to western and northern Scotland (although not including Orkney and Shetland). The main concentrations are centred within Sutherland, Wester Ross and the Outer Hebrides with breeding birds becoming scarcer southwards into Perthshire and Argyll as far south as Dumfries and Galloway. In the absence of ringing, it is not known where British breeding divers spend the winter.

Breeding habitat in Britain is normally large oligotrophic lochs amongst mountains, on open moorland or in lightly forested area. Breeding lochs, usually with large islets, have highly indented shorelines and support a typical aquatic vegetation where the emergent and edge species are mainly Carex spp. and Juncus spp. All breeding and feeding activities are normally carried out on these lochs or their immediate satellites; salt water is rarely used outside passage and wintering periods.

Knapdale

  • Knapdale Lochs SPA
  • Knapdale Lochs SSSI

Tayside

  • Rannoch Lochs SPA
  • Rannoch Lochs SSSI

See section 4.7.3.2 below with respect to Knapdale Lochs SPA and SSSI.

Rannoch Lochs SPA / SSSI

HRA Advice

For three of the lochs (Ossian, Laidon and Ba) the size of the loch and their major out flows are so large that beaver dams couldn't affect the water levels within the loch. None of the remaining 5 smaller lochs have areas of potential core beaver woodland on their shores or along their outflow burns. Colonisation of these lochs within the next 10 years is extremely improbable despite their inclusion in this appraisal due to both their distance from existing beaver locations and the nature of their habitat i.e. that of oligotrophic lochs with little available foraging resource for beavers.

The only physical impact the beavers would have on the lochs would be by raising the water level but this would not affect the divers if it remained stable. The lochs are mostly oligotrophic hill lochs and contain few macrophytes and are unlikely to be colonised by beavers during the next 10 years.

SNH HRA advice concluded that it can be ascertained that there is no adverse effect on site integrity of the Rannoch Lochs SPA as at present, and in the foreseeable future, because of the very low percentage of woodland cover in the catchment of the Rannoch Moor lochs (c. 2%), the harsh climate, and exposed nature of Rannoch Moor, meaning beavers are not expected to colonise the area. Therefore there will be no adverse effect on site integrity. In addition what woodland is present is adjacent to Loch Ossian and Loch Laidon: both of which are sufficiently large that beavers will not be able to raise the water level during a single diver breeding season.

SSSI Assessment

Impacts to Black throated diver in Rannoch Lochs SSSI are likely to be similar to those described above for the Rannoch Lochs SPA. While there are natural heritage interests of national importance on this site, these are unlikely to be affected by beaver activity.

Mitigation

No mitigation identified.

Scottish Crossbill

The Scottish Crossbill is globally endemic to the UK, where it occurs in the northern and eastern Highlands of Scotland. It is a species associated with remnant native Scots Pine Pinus sylvestris forests, and plantations of Scots Pine and other conifers. Breeding distribution is limited by suitable food supply, the main food being Scots Pine seeds.

Knapdale

There are no sites designated in the Knapdale beaver policy area for Scottish crossbill.

Tayside

  • Ballochbuie SPA
  • Cairngorms SPA
  • Creag Clunie and the Lion's Face SSSI

HRA Advice

Beaver activity may result in small areas of suitable habitat being lost within the SPAs. However, pine trees are known to grow in some wet habitats, e.g. bog woodland, within the Caledonian forest. Alteration of the woodlands to wetter types would not therefore result in complete loss of habitat for Scottish crossbill as the Scots pines are a key tree species in bog woodland. As noted in section 4.2 (Beavers and Woodlands) beaver also generally avoid felling pine trees, and other tree species form only a tiny component of bog woodland, therefore the extent of any loss of crossbill habitat will be very small.

SNH HRA advice concluded that, due to the ecological characteristics of the qualifier and the scale, nature and degree of potential impacts by beavers, there will be no adverse effect on the integrity of the Ballochbuie and Cairngorms SPAs.

SSSI Assessment

Impacts to Scottish crossbill in Creag Clunie and the Lion's Face SSSI are likely to be similar to those described above for the two above mentioned SPA. While there are natural heritage interests of national importance on this site, these are unlikely to be adversely affected by beaver activity.

Mitigation

No mitigation identified.

Geese & Swans

Each of the two geese and one swan species identified in Table 4.7.2 above are grouped together and discussed below.

Greylag Goose

Greylag Geese have a Palearctic distribution extending from Iceland in the west, discontinuously through Europe and central Asia to the Pacific shores of Russia). Two sub-species have been described, both of which occur in Europe, of which the nominate form occurs in west and north-west Europe, including the UK.

A number of distinct biogeographic populations of the nominate sub-species are recognised. Birds from the Icelandic breeding population of Greylag Goose winter exclusively in Great Britain and Ireland, most winter in Scotland, with concentrations in the Moray Firth, Aberdeenshire, eastern central Scotland, the central Southern Uplands and southwest Scotland.

Pink Footed Goose

The breeding areas of the monotypic Pink-footed Goose are globally restricted to eastern Greenland, Iceland and Svalbard. The geese migrate to winter in the countries surrounding the North Sea, meaning that the entire world population winters in just a few European countries. There are two biogeographical populations: those that breed in east Greenland and Iceland migrate to spend the winter months in Britain and Ireland, and those that breed in Svalbard that winter in the Netherlands, Denmark and Belgium. There is no mixing between these two populations which are separated throughout the year.

Most British-wintering Pink-footed Geese occur around estuaries between eastern Scotland and North Norfolk/The Wash. Up to three-quarters of Britain's wintering Pink-footed Geese are found in Scotland, with strongholds in Aberdeenshire, Perth, Kinross, Stirlingshire, the Lothians, and, in late winter, the Dumfries coast of the Solway.

Whooper Swan

The Whooper Swan is monotypic and has a Palearctic breeding distribution between 55οN and 70oN, from Iceland to the Bering Sea. They winter south to western Europe, the Black Sea, the Caspian Sea, central China and Japan. In the UK, most non-breeding Whooper Swans occur in northern Britain and Northern Ireland. Ringing recoveries indicate that the majority of these birds originate from the Icelandic breeding stock.

Knapdale

There are no sites designated for greylag or pink-footed goose or whooper swan located within the Knapdale beaver policy area.

Tayside

Pink footed goose

  • Firth of Tay and Eden Estuary SPA (& Ramsar)
  • Loch Leven SPA (& Ramsar)
  • Loch of Kinnordy SPA (& Ramsar)
  • South Tayside Goose Roosts SPA (& Ramsar)
  • Montrose Basin Ramsar (Dun's dish component only)
  • Inner Tay Estuary SSSI
  • Loch Leven SSSI
  • Loch of Kinnordy SSSI
  • Carsebreak and Rhynd Lochs SSSI
  • Dupplin Lakes SSSI

Greylag goose

  • South Tayside Goose Roosts SPA (& Ramsar)
  • Loch of Lintrathen SPA (& Ramsar)
  • Loch of Kinnordy SPA (& Ramsar)
  • Firth of Tay and Eden Estuary SPA (& Ramsar)
  • Montrose Basin Ramsar (Dun's dish component only)
  • Carsebreak and Rhynd Lochs SSSI
  • Loch of Lintrathen SSSI
  • Loch of Kinnordy SSSI
  • Loch Leven SSSI
  • Inner Tay Estuary SSSI
  • Hare Myre, Monk Myre and Stormont Loch SSSI
  • Lochs Clunie and Marlee SSSI
  • Meikleour Area SSSI
  • Drummond Lochs SSSI
  • Lochs Clunie and Marlee SSSI
  • Lochs of Butterstone, Craiglush and Lowes SSSI

Whooper swan

  • Loch Leven SPA
  • Loch Leven SSSI

HRA Advice

The Greylag geese which are qualifiers of SPAs tend to be in unfavourable condition because most of the Icelandic Greylags now winter to the north west of a line roughly from Bute to Aberdeen - mostly in Orkney & Caithness. The Pink-footed goose SPAs are in favourable condition because of the large increases in the Greenland / Iceland populations of these geese. Whooper swan populations in the UK are also increasing according to the International Surveys in 2010 and 2015.

Most of the Greylag, Pink-footed geese, and Whooper swans roosting on the inland SPAs are feeding on agricultural land, and importantly the availability of feeding areas is not considered to be a limiting factor on their populations. A recent paper in 'Ambio' states:

" Continental scale spatial and temporal shifts among geese undergoing spring fattening confirm their flexibility to respond rapidly to broad scale changes in agriculture. These dramatic changes support the hypothesis that use of agricultural landscapes has contributed to elevated reproductive success and that European and North American farmland currently provides unrestricted winter carrying capacity for goose populations formerly limited by wetlands habitats prior to the agrarian revolution of the last century".

SNH HRA advice concluded that it can be ascertained that there is no adverse effect on site integrity of the SPAs listed for greylag and pink-footed goose or whooper swan. This is due to the evidence that the availability of feeding areas is not a limiting factor in the populations of the qualifying geese, as well as the evidence for increasing Whooper swan populations in the UK. This evidence provides the basis for the advice that any minor, temporary reductions in extent of supporting habitat in the areas surrounding the five SPAs that may occur from flooding due to beavers will not have an AESI on them.

SSSI Assessment

Impacts to greylag and pink-footed goose and whooper swan features of the above mentioned SSSIs are likely to be similar to those described above for the aforementioned SPAs. While there are natural heritage interests of national importance on these sites, these are unlikely to be affected by beaver activity.

Mitigation

No mitigation identified.

Breeding Bird Assemblage

There are a number of sites within the beaver policy area that overlap with core beaver woodland designated for their breeding bird assemblage feature. This means the number of bird species recorded breeding across all the habitat(s) distributed within the site is significantly high to warrant special designation. For the purpose of this assessment only those species that utilise the woodland or standing freshwater / wetland habitats are considered.

Typical species of each breeding bird assemblage will depend on the woodland habitat type on site and may include those associated with the woodland edge and integral open habitat within the woodland, and so will generally include passerines (perching birds) such as those belonging to the following families: thrushes, flycatchers, tits and finches. Non-passerines may include bird species belonging to the following families: pigeons, owls, cuckoos, woodpeckers, falcons and hawks. Whilst those species more associated with standing freshwater or wetland habitats includes birds belonging to the following families: grebes, herons, wildfowl, kingfishers, rails. Impacts to relevant diver, geese and swan species are dealt with elsewhere as is Scottish crossbill.

Knapdale

  • Knapdale Woods SSSI

Tayside

  • Black Wood of Rannoch SSSI
  • Cairngorms SSSI
  • Dunalastair Reservoir SSSI
  • Dun's Dish SSSI
  • Dupplin Lakes SSSI
  • Eastern Cairngorms SSSI
  • Forest of Clunie SSSI
  • Inner Tay Estuary SSSI
  • Lindores Loch SSSI
  • Loch Leven SSSI
  • Loch of Kinnordy SSSI
  • Lochs of Butterstone Craiglush and Lowes SSSI
  • Moine Mhor SSSI
  • Shingle Islands SSSI

SSSI assessment

As described above, the evidence for effects of beavers on birds in Scotland is extremely limited. However, given that beavers are known to create diverse habitats rich in structural complexity. It would be expected that their presence would result in greater avian diversity than may be expected from the existing remnant riparian habitats in Scotland.

Specifically, the increase in amount of standing deadwood, for example, is likely to improve the avian diversity of the riparian zone. If deer grazing is controlled, the increased structural diversity resulting from the cyclical copping and regrowth of riparian trees is likely to open niches for species not found in mature closed canopy woodland, e.g. tree pipits. The increased shrub layer resulting from regeneration of three stools will also create habitat for a range of insectivorous songbirds particularly warblers. Inundation of woodland, leading to the death of standing trees, would also create feeding and nesting opportunities for a range of bird species including raptors, and deadwood feeders such as woodpeckers and nuthatch. Examples of scarcer native species that may benefit include marsh harrier and bearded tit which currently have populations within the sites identified above. Woodcook may benefit from use of areas of damp woodland and beaver ponds; osprey may benefit from an increase in the number of 'drowned' trees surrounding by wetland, providing potential nest sites and kingfishers may benefit from an increase in suitable slow moving freshwater habitat.

Studies at Knapdale ( SBT) have shown that beavers create woodland with a more open canopy and a more diverse field layer. If deer grazing is controlled, regrowth from gnawed stumps should also increase the shrub layer. This is a similar effect to coppicing, a management technique that has been shown to be beneficial to a range of declining woodland bird species in England. Dam creation at Dubh Loch has also increased the shallow water habitats available for nesting and feeding birds. Despite the lack of specific bird monitoring at Knapdale, it would appears that beavers have increased the diversity of the woodland structure and the amount of wetland habitats available for birds.

Therefore while there are natural heritage interests of national importance on these aforementioned sites, these are unlikely to be adversely affected by beaver activity.

Mitigation

No specific mitigation identified.

4.7.3.2 Consideration of potential negative effects on bird species of ecological and conservation importance

The impact of beaver activity on the bird species discussed below is considered to have a negative effect or have the potential for a negative effect.

Black Throated Diver

Scotland's fresh water environments are diverse, extensive, and typically have a high water quality. It's therefore no surprise that they support a wide range of bird species. The shores of nutrient-poor upland lochs are breeding sites for black-throated diver.

Within Britain, which is the extreme oceanic edge of its range, it is restricted to western and northern Scotland (although not including Orkney and Shetland). The main concentrations are centred within Sutherland, Wester Ross and the Outer Hebrides with breeding birds becoming scarcer southwards into Perthshire and Argyll as far south as Dumfries and Galloway. In the absence of ringing, it is not known where British breeding divers spend the winter.

Breeding habitat in Britain is normally large oligotrophic lochs amongst mountains, on open moorland or in lightly forested area. Breeding lochs, usually with large islets, have highly indented shorelines and support a typical aquatic vegetation where the emergent and edge species are mainly Carex spp. and Juncus spp. All breeding and feeding activities are normally carried out on these lochs or their immediate satellites; salt water is rarely used outside passage and wintering periods.

Knapdale

  • Knapdale Lochs SPA
  • Knapdale Lochs SSSI

Tayside

  • Rannoch Lochs SPA
  • Rannoch Lochs SSSI

See section 4.7.3.1 above with respect to Rannoch Lochs SPA and SSSI.

Knapdale Lochs SPA / SSSI

HRA Advice

Although all the lochs in the SPA are in catchments that contain potential beaver woodland only one has any of this type of woodland within 1km. Loch Fuar-Bheinne has potential beaver woodland approximately 900m downstream of its outflow. The likelihood of beavers colonising the SPA lochs would appear to be low but this assessment is based on the assumption that it is possible.

The site supports four pairs of breeding divers. Dam building in the outflow burns from the nesting lochs during the breeding season could cause changes in water levels that might flood nests with eggs or prevent adults brooding young. This would only occur if the birds nested on the shore. Beavers could have a direct impact if dam building took place during the nesting period. A dam established before breeding and which maintained a near constant water level would not have an impact. An increase in water level is unlikely to have an adverse impact on divers through indirect impacts to fish prey. Under natural conditions fluctuations occur both during, and outwith the breeding season. One loch in the SPA is used as a water supply for the Crinan Canal by Scottish Canals and to avoid impacts on the SPA water is only taken from this loch outwith the diver breeding season. If damming was prevented during the crucial part of the breeding season then there would be no adverse impact from beavers on the SPA lochs.

The birds will use the lochs in the SPA, and attempt to nest, irrespective of fluctuations in water level. The damming of an outflow burn on any particular loch will not affect the distribution of birds in the site. However their breeding distribution in the site would be affected as would the overall breeding success of the site. Therefore, as above, if damming was prevented during the key part of the breeding season would be no direct adverse impact from beavers.

SNH HRA advice concluded that it can be ascertained that there is no adverse effect on site integrity if the proposal is undertaken strictly in accordance with the following conditions.

SSSI Assessment

Impacts to Black throated diver in Knapdale Lochs SSSI are likely to be similar to those described above for the Knapdale Lochs SPA. There is therefore potential for beaver activity to adversely affect the natural heritage interest of national importance. See mitigation below.

Mitigation

No dam building by beavers in outflow burns of the SPA will be permitted during the period April to July inclusive. Any dams being built during that period should be removed without disturbance to the divers. If divers are breeding on the lochs within the SPA in any year then checking for beaver dams must be carried out without any disturbance to the breeding birds. Black-throated diver is listed on Schedule 1 of the Wildlife & Countryside Act 1981, as amended.


Contact