1. Introduction

1.1 Overview

ITPEnergised was appointed by SSE Renewables to undertake bat surveys within the onshore component of the proposed Berwick Bank offshore windfarm development at Torness, southeast of Dunbar, East Lothian (hereafter referred to as the ‘Site’). The site has central Ordnance Grid Reference: NT 74632 73282. The Study Area incorporated the Site and a 50 m buffer as shown in the location plan (Figure 7.3.1).

The work initially involved a Preliminary Roost Assessment (PRA) of trees, buildings and structures. Further to this, active season surveys were carried out for all trees, buildings and structures with potential roost features that lay within the footprint of proposed cable routes and a 30 m buffer (based on the potential design options at the time of the survey) were completed.

This report describes the methods used to gather and record information for the Site and summarises the findings of the study.  

1.2 Site Description

The Site is approximately 599.6 hectares (ha) in size and extends from north-west of Skateraw Harbour to Bilsdean in the south. The A1 trunk road and the East Coast Main Line (ECML) railway pass through the Site from the north-west to the south-east. The Site largely comprises agricultural land with a mixture of arable and grazed fields. Braidwood Burn and Ogle Burn run through the western reaches of the Site, Thornton Burn and Branxton Burn runs through the centre of the Site, Dry Burn runs through the north of the Site and Bilsdean Burn runs through the south of the Site. These watercourses are commonly associated with corridors of scrub and mixed woodland habitat.  The Site also encompasses a number of small hamlets and farm steadings. Larger settlements include Crowhill, Branxton and Lawfield to the south of the A1 and Skateraw and Thorntonloch to the north.  The Site includes an area of coastline at the landfall location to the north of Torness Point.     

2. Legislation

2.1 Legislation

2.1.1           Bats

All bat species within the UK are fully protected under the Conservation (Natural Habitat &c.) Regulations 1994 (as amended). Under this legislation, it is an offence to deliberately and/or recklessly:

    Capture, injure or kill a wild bat;

    Harass a wild bat or group of bats;

    Disturb a wild bat in a roost (any structure or place it uses for shelter or protection);

    Disturb a wild bat while it is rearing or otherwise caring for its young (this would be a 'maternity' roost);

    Obstruct access to a bat roost or to otherwise deny the animal use of the roost;

    Disturb such a wild bat in a manner that is, or in circumstances which are, likely to significantly affect the local distribution or abundance of that species; and to

    Disturb a wild bat in a manner that is, or in circumstances which are, likely to impair its ability to survive, breed or reproduce, or rear or otherwise care for its young.

It is also an offence to:

    Damage or destroy a breeding site or resting place of such an animal (whether or not deliberately or recklessly); and to

    Keep, transport, sell or exchange, or offer for sale or exchange any wild bat (or any part or derivative of one) obtained after 10 June 1994.

2.2 Good Practice Ecological Guidance

Cognisance has been taken of the following best practice guidelines and survey method publications in relation to bats:

       Bat Surveys for Professional Ecologists: Good Practice Guidelines (Collins, 2016);

       Bat Mitigation Guidelines (Mitchell-Jones, 2004);

       Bat Workers’ Manual (Mitchell-Jones and McLeish, 2004);

       Bat Roosts in Trees - A Guide to Identification and Assessment for Tree-Care and Ecology Professionals (BTHK, 2018); and

       Competencies for Species Survey: Bats (CIEEM, 2013)

3. Methods

3.1            Desk Study

A review of desk study data was completed to gather baseline information on bats. The following resource was consulted:

       ITPEnergised (2022) Berwick Bank EIA, Ecology Chapter, Technical Appendix 7.1, Preliminary Ecological Appraisal.

3.2 Preliminary Roost Assessment

3.2 Preliminary Roost Assessment

A Preliminary Roost Assessment (PRA) of the Site was conducted on the 7th, 8th and 9th June 2021 by ecologist and licensed batworker Stuart Abernethy (NatureScot Bat Licence No. 165055). Following a revision to the application boundary a survey of additional structures to the south-west of Skateraw was undertaken on 4th February 2022 by Jenny Diack, Senior Ecologist (NatureScot Licence 150746) and Helen Lamont, Ecologist. Trees, buildings and structures within the Study Area were assessed to identify potential roost features (PRFs), search for evidence of roosting bats and provide an overall assessment of roost suitability to inform further survey requirements using the BCT guidelines (Collins, 2016).

The ground-level inspection of trees, structures and buildings involved searching for the presence of features which could be of value to roosting bats, such as splits, cracks, rot holes, coverings of mature ivy, peeling bark (within trees) and raised slates, gaps under soffits or barge boards, crevices in stone or brick work (within buildings). Additionally, physical evidence of presence was also searched for (e.g. bat corpses, droppings, feeding remains, scratch marks, and urine and grease staining). The potential for the trees, structures or buildings to support roosting bats was ranked in accordance with the criteria set out in the BCT guidelines.

Roosting bats

Guidelines for assessing the potential suitability of the structure, building or tree to support roosting bats, based on the presence of suitable roost features, are given below:

       Negligible – Negligible roost features identified, not suitable for roosting bats.

       Low – A structure with one or more potential roost features that could be used by individual bats opportunistically. However, these potential roost features do not provide enough space, shelter, protection, appropriate conditions and/or suitable surrounding habitat to be used on a regular basis or by large numbers of bats (i.e. unlikely to be suitable for maternity or hibernation). Could also be a tree of sufficient size and age to contain PRFs but with none seen from the ground or features seen with only very limited roosting potential.

       Moderate – A structure or tree with one or more potential roost features that could be used by bats due to their size, shelter, protection, conditions and surrounding habitat bat unlikely to support a roost of high conservation status (with respect to roost type only – the assessments in this table are made irrespective of species conservation status, which is established after presence is confirmed).

       High – A structure or tree with one or more potential roost features that are obviously suitable for use by larger numbers of bats on a more regular basis and potentially for longer periods of time due to their size, shelter, protection, conditions and surrounding habitat.

Foraging/commuting bats

Guidelines for assessing the potential suitability of the Proposed Development Site for use by commuting and foraging bats, based on the presence of habitat features, are given below:

       Negligible – Negligible habitat features on Site likely to be used by commuting or foraging bats

       Low

• Habitat that could be used by small numbers of commuting bats such as gappy hedgerow or unvegetated stream, but isolated, i.e. not very well connected to the surrounding landscape by another habitat.
• Suitable, but isolated habitat that could be used by small numbers of foraging bats such as a lone tree (not in parkland situation) or a patch of scrub.

       Moderate

• Continuous habitat connected to the wider landscape that could be used by bats for commuting such as lines of trees and scrub or linked back gardens.
• Habitat that is connected to the wider landscape that could be used by bats for foraging such as trees, scrub, grassland or water.

       High

• Continuous high-quality habitat that is well connected to the wider landscape that is likely to be used regularly by commuting bats such as river valleys, streams, hedgerows, lines of trees and woodland edge.
• High quality habitat that is well connected to the wider landscape that is likely to be used regularly by foraging bats such as broadleaved woodland, tree-lined watercourses and grazed parkland.

Winter Hibernation Assessment

During the survey all trees, buildings and structures were also assessed as to their suitability to support hibernating bats.

3.3 Active Season Bat Surveys

3.3.1           Overview

During the surveys, surveyors watched for bats exiting potential roost features and recorded activity using bat recording equipment (see 3.3.4. below) for later analysis. The number of survey visits was based on the assessment of roost suitability with Low roost suitability structures surveyed over one visit and Moderate roost suitability trees/structures surveyed over two visits.  Survey dates and locations are described within Section 4.4.1.

3.3.2           Dusk Emergence

The dusk survey commenced 15 minutes prior to sunset and continued for a minimum of 90 minutes after sunset.  If late emerging species, such as brown long-eared or Myotis bats, were recorded during the survey, or had been recorded during a previous survey visit, surveys would continue until 120 minutes after sunset.  However, this was not the case.

3.3.3           Dawn Re-entry

The dawn survey commenced 90 minutes prior to sunrise and finished 15 minutes after sunrise.  During the survey, surveyors watched for bats entering potential roost features within the trees and structures.  If early returning species, such as brown long-eared or Myotis bats, had been recorded during the first dusk survey visit, the survey would have commenced 120 minutes prior to sunrise.  However, as mentioned above this was not the case.

3.3.4           Analysis

All bat activity was recorded using Batbox Duet FD recorders and Wav. recording devices.  Batbox Duet recordings were analysed using BatSound software for identification of bat calls to species level where necessary.

3.4 Survey Limitations

Bats do not always leave visible signs on the outside of roosting locations and, if present, these signs can often be removed through adverse weather conditions. Therefore, the absence of bat evidence does not necessarily equate to the absence of roosting bats. However, as features with potential suitability for roosting bats should be subsequently investigated in more detail, this is not considered a significant limitation.

Sound Analysis

Analysis of survey recordings (sonograms) was aimed at correlating bat echolocation calls to species, as far as possible, although there are limitations related to the identification of bat species solely from sonograms; these include:

       Some species, most notably Myotis species, have similar calls that cannot always be reliable separated;

       The quality of the recording is related to the proximity of the sound source to the detector and the presence of any obstructions. As such, faint and/or distorted calls may not be recorded in sufficient detail to allow identification;

       All bats can vary their calls substantially according to their environment and the purpose of the call, and therefore some calls may be atypical, thus making identification unreliable;

       As the peak frequencies of common pipistrelle (Pipistrellus pipistrellus) and soprano pipistrelle (Pipistrellus pygmaeus) can overlap, calls with peak frequencies of 50-51Khz were not identified to species level and were noted as pipistrelle bat (Pipistrellus spp.); and

       During one of the dawn surveys at Tree 19 on 27th July, a water pump was continuously running in close proximity to the tree. The resulting noise and interference meant that it was not possible to record bat activity for analysis. Visual observations of bat activity were considered sufficient to establish if bats were using potential roost features but species active in the vicinity of the tree could not be confirmed.

4. Results

4.1 Desk Study

Data received from TWIC (2021) shows that common pipistrelle, soprano pipistrelle, Myotis bat species, Daubenton’s bat (Myotis daubentonii), whiskered/Brandt’s bat (Myotis mystacinus/Myotis brandtii), Natterer’s bat (Myotis nattereri), noctule bat (Nyctalus noctula) and brown long-eared bat (Plecotus auritus) have been recorded within 5 km of the Site in the last 10 years. Table 1 below summarises the results of the bat data search.

Table 1. Bat species recorded within 5 km of the Site in the last 10 years

4.2 Habitat Assessment

The Site is well connected to habitats in the wider environment via the green and blue network of woodland strips and watercourses. Habitats within the Site provide a mosaic of suitable bat foraging, commuting, and roosting habitat, particularly along the wooded burn corridors of Thornton Burn, Dry Burn and Bilsdean Burn that lead into smaller tributaries and waterbodies including the Ogle Burn, Thurston Mains Burn, and Kames Well pond. Watercourses and waterbodies are likely to be utilised by species such as Daubenton’s bat, which specialise in foraging within riparian habitats.

The main areas of woodland that provide suitable commuting and foraging habitat for bats are located along the Thornton Burn, at the south edge of the Site boundary, and areas of woodland in the south east of the Site. The woodland sections within the Site provide sheltered foraging and commuting routes for bats and, as part of the green network, provide landscape features for bats to move between habitats of good value across the Site.

Arable land makes up the majority habitat of the Site and along the proposed cable route options (based on the design options at the time of the survey). Associated areas of hedgerow and scrub along field margins provide good foraging habitat and commuting routes for bats.

Scattered semi-mature and mature trees within the Site have features such as holes, cracks, crevices which provide numerous roosting opportunities for bats.

Overall, the habitats are assessed as High suitability for all bat species.

4.3 Preliminary Roost Assessment

All Target Notes and Photographs described within this section are contained within Annex A. Target Note descriptions for trees with potential roost features (PRF) within the Study Area are detailed in Table A1 and structures detailed in Table A2 with locations shown in Figure 7.32

4.3.1           Trees

Within the Study Area, 19 trees were identified with features suitable for use by roosting bats as described within Table A1, Annex A and shown on Drawing 7.32. Following consultation with NatureScot it was decided that where potential roost features lay within the footprint, or within 15 m of the Proposed Development (based on the design options at the time of the survey), further survey should be completed to confirm presence or absence of roosting bats. Two of the trees, TN16 and TN17, fell within the cable route or within the 15 m of proposed works (based on the design options at the time of the field surveys) and are described in Table 2 below. Both trees are categorised as having Moderate suitability for use as a summer roost and Negligible suitability for use as a winter roost.  Further survey of these trees was undertaken in 2021 to confirm presence or absence of roosting bats.

Table 2. Trees with Potential Roost Features within cable route option and 15 m buffer

4.3.2           Structures

Within the Site, six structures were identified with features suitable for use by roosting bats as described within Table A2, Annex A and shown on Figure 7.3.2 Of these structures, one ECML overbridge (TN24) lies within 15 m of proposed road widening works for an access road south of the A1 trunk road and is categorised as having Low bat roosting potential for use during the summer and winter as described in Table 3.

Table 3. Structures with Potential Roost Features within cable route option and 15 m buffer

4.4 Active Season Surveys

The results of the active season surveys are summarised below.  Full survey results are included within Annex B.

1.1                 

4.4.1           Survey Dates and Conditions

Table 4 below summarises survey dates and conditions for the active season survey visits and survey forms are provided in Annex B.

Table 4. Summary of Active Season Survey Visits

4.4.2           Tree 16

4.4.2.1     Survey visit 1 – Dawn Re-entry, 23.07.2021

No bats were seen returning to the tree during the survey. One soprano pipistrelle and one common pipistrelle were recorded foraging along the edge of treeline at 04:17.

4.4.2.2     Survey visit 2 – Dusk Emergence, 09.08.2021

No bats were seen leaving the tree during the survey. One bat was heard continuously foraging at the edge of the treeline, over the arable fields to the east of the surveyor location at 22:00.

4.4.3           Tree 17

4.4.3.1     Survey Visit 1 – Dawn Re-entry, 27.07.2021

No bats were seen returning to the tree during the survey. Bats heard on detector at 04:05 and 04:31 but no recordings due to background noise from water pump running close to survey location.

4.4.3.2     Survey Visit 2 - Dawn Re-entry, 10.08.2021

No bats were seen returning to the tree during the survey. Pipistrellus sp. were recorded foraging along the watercourse, passing four times at 04:05 and seven times at 04:19 and one Myotis bat was recorded commuting across the surveyor location at 04:33.

4.4.4           Bridge TN24

4.4.4.1     Survey Visit 1 – Dusk Emergence, 24.08.2021

No bats were seen emerging from the structure during the survey. One bat was recorded foraging in the field south of the bridge at 21:07 by the surveyor at the north side of the bridge and one bat was observed commuting across the Site at 21:19 by the surveyor at the south side of the bridge.