Abstract
- Lapwings Consultants Ltd has been commissioned by Centrica, through RPS Group, to undertake ecological surveys along the corridor of a proposed electricity cable taking power from off-shore wind farms to a new sub-station near Walpole St Andrew. The scope of the ecological surveys was to identify the use made of the study area by badgers, otters, water voles, spined loach, great crested newts, reptiles, foraging bats, the farmland breeding bird community, breeding waders on the saltmarsh, and to determine if any hedgerows are of nature conservation importance. The surveys were undertaken in the period mid-May to mid-July and early-mid September 2006.
- This report presents the results of the surveys and makes an assessment of nature conservation interest of the site for the groups concerned, and examines potential impacts from, and mitigation for, the proposed cable installation and sub-station construction.
- There are between 14 and 19 pairs of redshank nesting on the area of saltmarsh directly out from the east-west running sea wall and possibly 1 pair of oystercatchers.
- 77 birds species were recorded using the farmland cable route corridor, of which 49 species were breeding and 10 species were probably breeding, with no breeding activity being observed for the remaining 18.
- The most notable breeding species were marsh harrier (Annex 1 Birds Directive and Wildlife & Countryside Act Schedule 1); and grey partridge, turtle dove, skylark, song thrush, spotted flycatcher, tree sparrow, linnet, reed bunting and corn bunting (all UK BAP Priority Species). Also breeding and on the BTO Red List as Species of High Conservation Concern were starling, house sparrow and yellowhammer. Breeding birds on the BTO Amber List as Species of Medium Conservation Concern were oystercatcher, stock dove, cuckoo, swallow, house martin, meadow pipit, yellow wagtail, dunnock, mistle thrush and goldcrest.
- No signs of badger use of the part of the cable route study area to which there was accesses were seen, and no setts were found. No road casualty badgers were seen. No signs of use of the study area by water vole and otter, where access was allowed, were seen. No reptiles or their field signs were seen along the cable route corridor or around the periphery of the existing sub-station. None of the drains were suitable for spined loach. No great crested newts were found in the ponds at Rose Hall Farm, the pond NW of Kamerad Farm, or the pond at Crown Farm at Walpole Cross Keys.
- The foraging bat surveys show that the area of the cable route and proposed substation is used by 3 species of bat for foraging (Daubenton’s bat, 45 pipistrelle bat and an unidentified Myotis species) and may be used by a fourth species (55 pipistrelle bat). The activity of the Daubenton’s bat was centred on a large wet drain, whereas the pipistrelle activity occurred over terrestrial habitats, with some use also being made of the drains. Pipistrelle activity is centred on areas of shelter, which was provided by woodlands, field and roadside boundaries and farm and domestic buildings. The single record of the Myotis bat was made near a drain. There is very little or no bat activity in the extreme north of the cable route corridor and there is very little use of the arable land.
- The diversity of native woody species in field boundary and roadside hedges is very limited and no hedgerow reaches or exceeds the threshold for importance for UK Biodiversity or for wildlife under the terms of the Hedgerow Regulations.
- The proposal for the cable to be directionally drilled under the entire saltmarsh would avoid significant adverse impact on the waders using the marsh at any time of year.
- The installation of the cable and construction of the substation have the potential to cause loss of occupied nests and disturbance to breeding birds. Mitigation options could include timing of all or part of the works to avoid the bird breeding season; the identification of which crops would not be suitable for breeding harriers or waders and use these crops once a preferred route had been identified; directionally drill under major watercourses; and the management of field boundary and ditch habitats such that they are temporarily unsuitable for breeding birds.
- Currently there would be no impact on badger since no setts would be affected, no significant foraging areas lost or disturbed, and no well-used paths blocked. However, once the preferred route is known, it would be necessary to monitor the use of this by badgers in case a sett became established and/or an area became used significantly for foraging. Currently, no badger mitigation is required, and if the monitoring continues to show that this situation is same, no mitigation would be required in the future. However, since it is known that badgers do use the area at a very low level, it would be necessary to ensure that badgers did not come to harm by falling into open excavations by using simple mitigation measures. If the monitoring results in the discovery of a badger sett which may be affected by the proposed works, it would be necessary to immediately close the sett, under the terms of a licence.
- There would be no impact from the installation of the cable or the construction of the substation on otters. There is no need for mitigation for this species. The directional drilling of the cable under the larger wet drains would ensure that otters on passage would not be affected.
- Since water voles are absent there is no potential for adverse impact on this species. However, since water voles may be present outside the corridor and could colonise in future, the proposed directional drilling of the larger wet drains would remove any potential for impact should water voles occur.
- There would be no impact on spined loach. There is no need for mitigation for this species. The proposed directional drilling of the larger wet drains would ensure that if spined loach did occur in these watercourses there would be no significant affect.
- The majority of the proposed cable route has very little potential to support reptiles and since it is likely that none or very few are present, the potential impact would be insignificant. The directional drilling of the larger wet drains and roads would not affect these habitats and any reptiles present. Elsewhere the cable route may affect habitats with reptiles, but mitigation undertaken in advance of the works including removing refuges and close cutting of vegetation would ensure that no reptiles were inadvertently killed or injured.
- Given the very limited use by bats of the open farmland, the potential impact of cable installation and substation construction would be insignificant. Potential impacts of greater significance may occur where linear features used by bats (ie hedges, lines of trees, lines of bushes and the larger wet drains) are affected by being temporarily breached. Mitigation would reduce this potential impact by temporarily covering the breach such that bats do not perceive gap which they may not cross. Breaches in hedges can be reinstated by planting. The directional drilling of the larger wet drains would not alter the habitat for bats therefore the potential impact would be of no significance.
- From Marsh Road north to the sea wall, the potential impact on great crested newts is likely to be insignificant. No breeding pond would be affected. No mitigation is necessary. From Marsh Road southwards, the potential impact is not known; it may be of no significance. It is recommended that further attempts are made to gain access to the ponds where no survey was undertaken in order to determine if newts occur, to identify potential constraints.
- The potential impact on hedgerows is not significant. Short lengths may be temporarily lost, but reinstatement of the gaps would restore the hedges.