As an example of how digital report will look like in the final version of the digital EIA, here we have made a digital version of the Ornithology Valuation Assessment which has been previously produced.
1. Introduction
Gwynt Glas Offshore Wind Farm Ltd is exploring siting options for the Gwynt Glas Offshore Wind Farm (Gwynt Glas) in the Celtic Sea. Natural Power has been asked to provide an evaluation of ornithological sensitivities within the development option area.
The Gwynt Glas development option area is located west of the Bristol Channel, in the Celtic Sea, and consists of an area of approximately 1,500 km2. The area straddles the boundary between Welsh and English territorial sea limits (Figure 1). The site lies 56 km from the Welsh coast and 45 km from the English coast, at their nearest points.
For the purposes of this ornithological assessment, the option area has been divided into three sub areas, named sub area A (covering Welsh territorial waters), sub area B (English waters: north) and sub area C (English waters: south). Where possible, a comparison has been made between these three sub areas, regarding their relative importance to key ornithological features.
This document comprises the following:
Desk-based review of existing ornithological data, including European Seabird at Sea (ESAS) data and seabird tracking data relevant to the Gwynt Glas development area; as well as ornithological data contained within reports available for neighbouring offshore wind farm projects (where available);
The site-specific contemporary Digital Aerial Survey (DAS) data collected as part of baseline recording (April to September 2021 inclusive), covering the Gwynt Glas option area and a 4 km surrounding buffer;
Additional DAS data to form further baseline recording (October 2021 to March 2022 inclusive) covering the Gwynt Glas option area and a 4 km surrounding buffer;
Details of ornithological features of interest; and
A summary of the main findings and recommendations.
2. Desk-based Review
A desk study/data search has been undertaken to find existing data that can be used to inform the ornithological sensitivity assessment for Gwynt Glas.
Two other offshore wind farm (OWF) projects are currently being proposed close to Gwynt Glas: Erebus OWF and Valorous OWF (Figure 1). This desk study has looked at these two projects to determine if the baseline data and/or assessments collated so far provide data that is relevant and informative to the Gwynt Glas project.
In addition to these projects, Llŷr 1 and Llŷr 2 (south of the Pembrokeshire coast) and Whitecross (north of the Devon and Cornwall coasts) are three 100-megawatt (MW) demonstration sites currently going through plan-level Habitats Regulations Assessment (HRA), prior to agreements for seabed lease being granted. Due to the early stage of these developments, no data is yet available and these projects are not discussed further.
The desk study has also looked at existing seabird data that has been gathered over many years through at sea surveys across the wider area and through tracking of seabirds from specific breeding colonies. Details of these data searches are provided below.
2.1 Erebus Offshore Wind Farm
The proposed Erebus floating offshore wind farm project lies to the north of Gwynt Glas. The planning application for Erebus was submitted in December 2021 and thus the associated documentation1, including the Offshore Ornithology chapter of the Environmental Statement (ES), was available to consult as part of the desk-based review. The project shall consist of between six and 10 wind turbines and have a capacity of up to 100 MW. The Erebus site is relatively small in extent (43 km2) and, importantly, it lies closer to the Welsh coast than Gwynt Glas (35 km from the Pembrokeshire coastline). Despite these differences, the baseline data collected for Erebus provides a useful resource when identifying the potential key ornithological features that may need to be considered for an offshore wind farm in the eastern part of the Celtic Sea.
Baseline Surveys and Assessment
The Erebus site was surveyed using data collected by 24 months of DAS (October 2019 to September 2021 inclusive). In addition, specially commissioned reports were produced to inform the assessment, covering:
An analysis of tracking data from the Grassholm gannet project (Heriot Watt University);
Guillemot long-term survival data from Skomer (University of Sheffield); and
An analysis of OxNav Manx shearwater tracking data (University of Oxford).
The latter report also included expert opinion in regard to the importance of the area for Balearic shearwater.
Main Findings
Based upon the results of the baseline surveys, the key ornithological features were considered to be: northern fulmar (fulmar), Manx shearwater, gannet, herring gull, lesser black-backed gull, black-legged kittiwake (kittiwake), puffin, common guillemot (guillemot) and razorbill.
The other seabird species recorded, but which were only recorded infrequently and were considered to be transient, or to have a more inshore distribution, were: great skua, black-headed gull, common gull, Sabine’s gull, little gull, Sandwich tern, common tern and Arctic tern.
Two other species were assessed in the impact assessment, despite not being recorded during baseline surveys: Balearic shearwater and storm petrel. This was the result of pre-application discussions with Natural Resources Wales (NRW), the Joint Nature Conservation Committee (JNCC), the Royal Society for the Protection of Birds (RSPB) and the Wildlife Trust of South and West Wales (WTSWW).
The Erebus ecological impact assessment (EcIA) concluded negligible or minor adverse impacts, and no significant effects, on all ornithological features. The cumulative impact assessment also concluded no significant effect on all ornithological features.
As well as the ES, the Erebus project produced a Habitats Regulations Assessment: Report to Inform Appropriate Assessment (MarineSpace Ltd, 2021). Breeding species that were taken forward to Stage 2 (Assessment) were: gannet, Manx shearwater, lesser black-backed gull, kittiwake, guillemot, razorbill and puffin. Balearic shearwater and storm petrel were also taken forward to Stage 2 following consultation.
Potential connectivity between these species and breeding seabird SPAs (using foraging ranges) identified 152 SPA sites. A site-specific apportioning analysis was undertaken, and this concluded that, for all the species considered, a proportional weight for the closest SPA was >0.8, and for the second closest SPA, the proportional weight was <0.04. Therefore, effects to any SPA other than the closest, were considered to be negligible.
Skomer, Skokholm and the Seas off Pembrokeshire SPA was the closest SPA for most of the considered species. The proportional weight for each species (i.e. the proportion of individuals recorded on site considered to have come from this SPA) were: puffin (0.997), Manx shearwater (0.995), lesser black-backed gull (0.978), razorbill (0.892), kittiwake (0.817) and guillemot (0.754). For gannet, the closest SPA was Grassholm (0.995 proportional weight).
Following assessment of these species, for the potential impacts identified, it was determined for all ornithological features that are designated features of the Skomer, Skokholm and the Seas off Pembrokeshire SPA that there was no potential for adverse effect on integrity. The in-combination assessment also determined no potential for an in-combination adverse effect on integrity. The same conclusions were made for Grassholm SPA. Note that both guillemot and gannet were subject to Population Viability Analysis as part of the assessment.
The Irish Sea Front SPA was also assessed, as one of its conservation objectives is to “ensure access to the site from linked breeding colonies”. No potential for an adverse effect on integrity was concluded.
2.2 Valorous Offshore Wind Farm2
Scoping Report
The Scoping Report3 for the proposed Valorous OWF was produced in early 2021. This site lies adjacent to Erebus, to the north of the Gwynt Glas development area. The Valorous project has an outline area of interest of c.155 km2 and lies approximately 47 km south-west of the Pembrokeshire coast. Capacity of the project shall be up to 300 MW and shall consist of between 18 and 31 wind turbines.
The Scoping Report states that baseline surveys shall consist of monthly DAS beginning in March or April 2021 and, therefore, these surveys had not begun at the time the Scoping Report was written. Hence, no site-specific baseline data is presented in this scoping document.
A desk-based study was undertaken, however. A search of ESAS data determined that the Valorous array area is important in the breeding season for Manx shearwater, gannet, kittiwake and puffin. In winter, the site is likely to be of importance for guillemot, with an extensive area further offshore, to the south-west, considered to be of interest for its large numbers of wintering lesser black-backed gulls. Data from tracking studies showed the area is used extensively by razorbill and is also used frequently by puffin. The possibility of species of tern being recorded during migration times is also highlighted.
Scoping Response
Regarding offshore ornithology, the Scoping Response4 does not offer much guidance in relation to Gwynt Glas, as without having baseline data to comment upon, all ornithological features require ‘scoping in’ to the ES. However, of interest is a comment from the RSPB that Balearic shearwater also be included in the EIA, as this species is ‘critically endangered’ and is known to occur in the Celtic Sea.
2.3 Llŷr Offshore Wind Farm
Scoping Report
The Scoping Report5 for the proposed Llŷr OWF was produced in April 2022. The site, consisting of two adjacent array areas known Llŷr 1 and Llŷr 2, lies adjacent to Erebus, to the north of Gwynt Glas. The Llŷr project has an outline area of interest of 50 km2 and lies approximately 31 km from the Welsh coastline. The capacity of the project will be up to 200 MW and consist of between 10 and 17 floating wind turbines.
The Scoping Report states that 24 months of monthly DAS surveys will be used to characterise the baseline data, however no specific date ranges were mentioned in the report and no DAS data is provided. Hence, no site-specific baseline data is presented in this scoping document.
Identified in the Scoping Report was that the OWF will pass directly through the Skomer, Skokholm and the Seas off Pembrokeshire SPA, designated for its Manx shearwater, storm petrel, puffin and lesser black-backed gull, as well as a wider seabird assemblage. The Scoping Report also included potential impacts to birds not yet included in the current Gwynt Glas assessment, such as attraction of nocturnal seabirds (e.g. petrels and shearwater) to project infrastructure lighting and increased entanglement risk to diving seabirds from ghost fishing gear catching on project infrastructure.
Scoping Response
Regarding offshore ornithology, the Scoping Response5 does not offer much guidance in relation to Gwynt Glas, as without having baseline data to comment upon, all ornithological features require ‘scoping in’ to the ES. RSPB comments regarding Balearic Shearwater were also mentioned within this document as per the Valorous project.
2.4 White Cross Offshore Wind Farm
Scoping Report
The Scoping Report6 for the White Cross Offshore Wind Farm was produced in January 2022. The site, consisting of up to eight floating turbines to deliver up to 100MW, is located over 52 km off the North Cornwall and North Devon coast. The scoping report includes an initial 12 months of DAS data, as surveys commenced in July 2020 and were completed in June 2021.
Main Findings
Based upon the results of the baseline surveys, the key ornithological features were considered to be: common tern, northern fulmar (fulmar), gannet, great black-backed gull, common guillemot (guillemot), herring gull, black-legged kittiwake (kittiwake), lesser black-backed gull, Manx shearwater, puffin, razorbill and sandwich tern. The most abundant species group were shearwaters, recorded during July and August 2020, as well as March to June 2021(almost all Manx shearwater from Skomer, Skokholm and the Seas off Pembrokeshire SPA).
In addition to the offshore ornithology receptors identified to species level and reported above, a further nine species groups were identified. These were common or Arctic (“commic”) tern, auk or shearwater, unidentified auk, black-backed gull species, unidentified large gull, unidentified shearwater, unidentified small gull, storm-petrel and unidentified tern.
Waggitt et al. (2020) Data
Waggitt et al. (2020) produced distribution maps for a number of seabird (and marine mammal) species in the north-east Atlantic, by compiling and standardising data from dedicated aerial and vessel surveys, undertaken between 1980 and 2018. They were able to model distribution maps for 12 bird species: fulmar, Manx shearwater, storm petrel, shag, gannet, great skua, kittiwake, herring gull, lesser black-backed gull, puffin, guillemot and razorbill. The outputs display distribution/density maps at 10 km and calendar month resolution, and these have been used to inform this assessment.
To create the figures that are presented within this report, the mean distribution of each species was calculated for each season, using the ‘mosaic raster layers’ tool in QGIS. The output of this was then clipped to the area of interest. In order to standardise the maps for each of the species, the minimum and maximum averages for all the seasons were then applied to all maps for that species. The resolution of the figures uses a 10 km2 scale, however densities are shown as birds per km2.
It should be noted that because of the way the figures in Waggitt et al. (2020) were produced, the density figures presented in this report generally show the same distribution of birds in all seasonal maps shown for that species, when in reality there is likely to be variation between the breeding and non-breeding seasons. Also, in Natural Power’s experience, the densities given in Waggitt et al. (2020), have been shown to be under-estimates in some cases. However, this still remains a very useful resource in determining relative densities and distributions of seabirds in the waters around the UK.
2.6 Seabird Tracking Database
The Birdlife International seabird tracking database7 includes data of seabirds tracked at sea, using GPS tags attached to birds from UK breeding colonies. Tracking data of relevance to Gwynt Glas includes data for gannets tagged on Grassholm and puffins, kittiwakes and razorbills tagged on Skomer.
2.7 Literature Search
In addition to the data sources listed above, other relevant published papers have been cited, where this provides further information regarding the distribution or ecology of the ornithological features identified as being of interest in relation to the Gwynt Glas project.
3. Baseline DAS Data
The current programme of digital aerial surveys, undertaken as part of baseline recording, began in April 2021. Data available for April to September (inclusive) (broadly covering the breeding and post-breeding seasons) is presented within this document. Each survey uses 25 parallel transects, running in a north-west to south-east orientation, to cover the array area, plus a 4 km surrounding buffer.
The programme of surveys aims to collect data for the site and buffer once per calendar month, where weather conditions allow. In months in which a survey was not possible, the survey shall be completed as soon as possible in the following month.
During the first iteration of this report (issued April 2022) data collected during surveys undertaken in the period April to September 2021 (inclusive) was summarised. In that period six DAS were carried out. In this, the second iteration of this report, additional data collected during the period October 2021 to March 2022 (inclusive, a further six DAS) is incorporated. Details of the times and dates on which the twelve DAS informing this report were conducted are provided in Table 1.
Table 2 provides an overview of all species recorded during the DAS campaign April 2021 to March 2022. The raw data has been filtered to remove records of birds that lie outside the site boundary and 4 km buffer. In the table, ‘September (I)’ refers to the 2 September 2021 survey and ‘September (II)’ refers to the 15 September 2021 survey. Those species that totalled ≥100 records are marked in bold.
No Balearic shearwaters have been recorded during the survey period, however the JNCC flagged that they could be found in the Celtic Sea through winter as they transfer regions and can be difficult to ID from Manx shearwater.
In Section 4, the number and density of the key ornithological features are presented for the Gwynt Glas Area of Search, the 4 km surrounding buffer and for the three sub areas. Densities have been calculated using the assumption that the area covered by the video imaging collected during the DAS (‘strip width’) is 250 m.
4. Ornithological Features of Interest
Based upon the site-specific baseline DAS, completed during April 2021 to March 2022, the following species have been identified as being potential ornithological features of interest at Gwynt Glas: fulmar, Manx shearwater, storm petrel, gannet, herring gull, lesser black-backed gull, puffin and guillemot. These species were recorded most frequently (≥100 records) and are considered likely to require full assessment in the EIA. In the first six months of DAS, kittiwake and razorbill were recorded in relatively small numbers, however they were recorded in much greater numbers in the second six-month period (post-breeding and wintering periods) and these two species are also now considered to be ornithological features of interest (≥100 records).
Finally, Balearic shearwater should also be included in the list of ornithological species of interest. Although not recorded during the baseline DAS completed in April 2021 to March 2022, the consultee responses in relation to both Erebus and Valorous OWFs highlight the conservation status of this species (critically endangered) and the potential for this species to utilise the eastern Celtic Sea.
The seabird species listed above are described in detail in this section of the document.
It should be noted that the list of ornithological features assessed in this section is not comprehensive. Other species have been recorded in small numbers in the baseline surveys (Table 2) and it is possible that the status of these species may change as the programme of baseline surveys continues, or that further species may be recorded. Of the other species listed in Table 2, great black-backed gull is the next most abundant species, after those listed above and may also require consideration in future.
An important point to consider is that the conservation status of the potential ornithological features of interest identified (or other species) may change, particularly in response to the highly pathogenic avian influenza (HPAI) outbreak which has been impacting UK seabird populations since the 2022 breeding season. The magnitude of impacts of the HPAI outbreak on these bird populations is currently unknown.
4.1 Determining Reference Populations of Ornithological Features
For most seabird species there are a number of years after fledging before a bird becomes sexually mature, and not all adult birds may breed in any given year. Even so, the majority of seabirds recorded on site during that species’ breeding season can be considered to be breeding birds. An assessment of impacts therefore needs to identify the likely source of the breeding birds on site in order to determine i) the size of the population utilising the site, compared to the size of the breeding population from which these birds are drawn, and ii) any potential connectivity with SPAs that have breeding seabirds as a designated feature.
To determine whether a site has potential connectivity with an SPA, the mean maximum foraging distance is commonly used. A more precautionary approach is to use mean max foraging distance plus one standard deviation (+1SD) and this measure is now the one usually requested by consultees. This data is provided in Woodward et al. (2019).
Table 3 lists the SPAs with potential connectivity to the Gwynt Glas Area of Search, based upon the foraging distance of the ornithological features of interest. For all species, except fulmar, mean max foraging distance +1SD has been used to identify SPAs. The extensive foraging range of fulmar (1,200 km, if using mean max +1SD) means that a very large number of SPAs fall within this area. However, as the impacts apportioned to these distantly located designated sites would be negligible in magnitude, consideration is restricted to mean maximum foraging distance for this species.
The SPAs are located in the four nations of the UK, as well as Ireland and France. Table 4.1 should not be regarded as a complete list of all colonies, but rather its inclusion in this document is to provide an illustration as to the magnitude of the breeding population against which those in the site should be assessed. Only SPAs are listed, but other sites with a statutory designation, and which include breeding seabirds in their citation, shall also lay within these search areas (for example Lundy Site of Special Scientific Interest (SSSI)).
The populations stated in Table 4.1 are those given in the SPA citation. The number of breeding birds may now differ from these values. ‘Prs’ refers to population sizes, estimated by numbers of pairs, and ‘ind’ refers to population sizes, estimated by the number of individuals. Distances are not the shortest distance between the proposed development site and the protected area, but rather the minimum distance ‘by sea’ that a seabird would need to travel to move between the two sites without crossing land.
One SPA lies very close to the option area (Skomer, Skokholm & the Seas of Pembrokeshire SPA) and the location of this in relation to Gwynt Glas is shown on Figure 1, Appendix A.
References
Waggitt, James J., Peter G. H. Evans, Joana Andrade, Alex N. Banks, Oliver Boisseau, Mark Bolton, Gareth Bradbury, et al. 2020. “Distribution Maps of Cetacean and Seabird Populations in the North-East Atlantic.” Edited by Andre Punt. Journal of Applied Ecology 57 (2): 253269. https://doi.org/10.1111/1365-2664.13525.
Footnotes
Available at: Document Library | Blue Gem Wind [last accessed 03/02/2022]↩︎
Available from: Microsoft Word - VAL-CON-MAR-REP-ENV-0002 Scoping Report B01 (bluegemwind.com) [last accessed 03/02/2022]↩︎
Available from: Public register - Customer Portal (naturalresources.wales) [last accessed 03/02/2022]↩︎
Available from: Seabird Tracking Database [last accessed 09/02/2022]↩︎
Available from: Public register - Customer Portal (naturalresources.wales) [last accessed 20/10/2022]↩︎
Available from: PC2978_RHD-ZZ-XX-RP-Z-0009-White-Cross-Offshore-Windfarm-EIA-Scoping-Report.pdf (whitecrossoffshorewind.com) [last accessed 21/10/2022]↩︎
Available from: Seabird Tracking Database [last accessed 09/02/2022]↩︎