6.4. Offshore Ornithology

6.4.1. Introduction

This section of this Scoping Report considers the scope of assessment on offshore ornithology from the construction, operation and maintenance, and decommissioning of the Array (seaward of the Mean High Water Springs (MHWS) mark).

6.4.2. Study Area

This Scoping Report (and subsequently the Array EIA Report) will largely be informed by data collected within the offshore ornithology aerial survey study area, which encompasses the site boundary plus an 8 km buffer ( Figure 6.6 Open ▸ ). Digital aerial surveys commenced in March 2021 and were completed in February 2023. A total of 31 survey transects spaced 2.5 km apart will provide approximately 10% survey coverage of the offshore ornithology aerial survey study area. The full baseline dataset will consist of data from 24 monthly surveys (i.e. a single survey has been completed each calendar month). As is standard for assessments for proposed offshore wind farm developments in Scotland, and elsewhere in the UK, these survey data will be used to characterise the baseline in terms of the bird populations using the Array and its surrounds (as defined by the offshore ornithology aerial survey study area). Assessments of the effect pathways that are likely to be relevant to the Array (including collision risk, displacement and barrier effects, habitat loss and indirect effects on prey availability) will be determined on the basis of these data.
The 8 km buffer is considered an appropriate size to provide a robust baseline for pre- and post-construction comparisons of seabird abundance and distribution along a gradient outward from the site boundary. The survey area is anticipated to encompass areas beyond which effects resulting from the construction and operation of the Array are predicted to occur for key species recorded within the area. This is particularly relevant in relation to displacement and barrier effects. In this respect, it is considered highly unlikely that species which may respond to displacement over larger distances (notably red-throated diver Gavia stellata) will occur within the offshore ornithology aerial survey study area, other than as rare and sporadic records. This is due to the distance of the Array from the coast, noting that no red-throated diver were recorded during the first year of surveys.
As per the SMP Appropriate Assessment (Scottish Government, 2019a), a separate programme of “regional” surveys is ongoing. These commenced in March 2022 [8]. It has been agreed with Marine Scotland that the regional survey data will be supplied to Marine Scotland for the purposes of informing the Iterative Plan Review (IRP) of the SMP, and that this data will not be used to characterise the baseline of the offshore ornithology aerial survey study area and therefore not used within the Array EIA Report (confirmed via email from Marine Scotland Planning and Policy, received on 31 January 2023).
Ongoing focused consultation with MSS, MS-LOT, NatureScot, and the RSPB Scotland will continue to inform the scope and methods of the analysis and assessment of the Array EIA Report, as per the approach presented in the dSEP (Appendix 1).

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Figure 6.6: Offshore Ornithology Aerial Survey Study Area, with the Survey Transects Shown

6.4.3. Baseline Environment

The Array lies offshore to the east of the Forth and Tay region. Both the Firth of Forth and the Firth of Tay are recognised as important areas for birds (Fisher et al., 2000). The Forth and Tay region supports internationally important populations of northern gannet Morus bassanus, auk and gull species, which is reflected in the multiple Special Protection Area (SPA) designations for these, and other species, across the region (Stroud et al., 2016). In addition, the Array also lies relatively close to areas of the Angus and Aberdeenshire coasts, which support a number of internationally important breeding and non-breeding sites for offshore ornithology receptors.
There is a considerable amount of existing information relating to the population sizes and trends, demographics, seasonality, distribution, and variation in offshore ornithology receptor populations in and around the outer Firth of Forth and the wider Forth and Tay region. These data are available as a result of scientific research (for example at the Isle of May and Bass Rock, as well as studies which have used seabird tracking data from multiple colonies to produce modelled at-sea distributions), and surveys and data collection programmes associated with existing offshore wind farm developments. These include Seagreen 1 (formerly known as Seagreen Alpha and Bravo) and Seagreen 1A, Neart na Gaoithe, and Inch Cape Offshore Wind Farms, and more recently (March 2019 to April 2021), baseline ornithological data collection in the form of digital aerial surveys for the Berwick Bank Offshore Wind Farm. It is therefore considered that regional seabird distribution, abundance, and seasonality of the wider area in which the Array is situated is relatively well understood. This existing data will be used to place the site-specific survey data within a regional context.
The following sections provide a summary of general baseline characteristics of seabirds in the vicinity of the site boundary, divided into breeding, wintering and passage periods. These accounts make use of published information, in addition to the available raw baseline survey data from the offshore ornithology aerial survey study area, which consists of data from monthly surveys carried out between March 2021 and February 2022. Due to the availability of only a single year of baseline surveys, this is not intended to be a comprehensive review of the baseline condition of the offshore ornithology aerial survey study area, particularly since the ongoing Highly Pathogenic Avian Influenza (HPAI) outbreak has the potential to result in quite substantial changes to the baseline environment. Instead, this information should be viewed as a summary of the raw survey data to date.

Breeding season

Baseline survey data collected from the offshore ornithology aerial survey study area between March 2021 and February 2022 indicate that the most numerous species in the offshore ornithology aerial survey study area during months associated with the ‘generic’ seabird breeding season (defined here as April to August) are (in descending order) common guillemot Uria aalge, black-legged kittiwake Rissa tridactyla, gannet, Atlantic puffin Fratercula arctica, northern fulmar Fulmarus glacialis and razorbill Alca torda.
The abundance of auks, kittiwake and gannet is consistent with the presence of internationally important breeding seabird colonies around the coast and islands of the Firths of Forth and Tay. Colonies of particular importance include the Forth Islands SPA (SNH, 2018), which includes the Isle of May and Bass Rock, the sea cliffs of St Abb’s Head to Fast Castle SPA (SNH, 2009a), and Fowlsheugh SPA (SNH, 2009b). The breeding success and population sizes of some species at these colonies are in decline, reflecting what appears to be general trends for seabirds in the North Sea (JNCC, 2020b, 2022; Mavor et al., 2001, 2008; Parsons et al., 2008).
Guillemot and razorbill were recorded throughout the offshore ornithology aerial survey study area during April to August in the first year of baseline surveys. Records of both species were much more frequent in the north-western extent of the offshore ornithology aerial survey study area than the south-western extent, with the density of records decreasing down a gradient between these two regions. It should also be noted that both species were much more frequently recorded in the region to the west of the offshore ornithology aerial survey study area, than within the offshore ornithology aerial survey study area itself. In general, higher numbers of birds were recorded in areas closer to the coast. Published sea utilisation distributions indicate that in the case of guillemot and razorbill, the offshore ornithology aerial survey study area is outside the home range (i.e. beyond the extent of the 95% utilisation distribution) of breeding birds from all UK and Republic of Ireland breeding colonies during the late incubation and early chick rearing period (Cleasby et al., 2018, 2020; Wakefield et al., 2017). These modelled utilisation distributions suggest that higher numbers of birds occur in areas of sea closer to the coast during the period of the breeding season covered, for which these modelled data are particularly relevant. Whilst this does not exclude the possibility of breeding birds being present in the offshore ornithology aerial survey study area during the breeding season (particularly outside the late incubation and early chick rearing period), it does suggest that other areas of sea are likely to contain larger numbers of breeding birds during the breeding season. From this, it is considered likely that a relatively high proportion of guillemot and razorbill recorded in the offshore ornithology aerial survey study area during the breeding season, particularly during the late incubation and early chick rearing period, may be non-breeding birds.
Published at sea utilisation distribution datasets indicate that for kittiwake, the offshore ornithology aerial survey study area is outside the core home range (i.e. beyond the extent of the 50% utilisation distribution), but within the wider home range (i.e. within the extent of the 95% utilisation distribution) of breeding birds from all UK and Republic of Ireland breeding colonies (Cleasby et al., 2018, 2020; Wakefield et al., 2017). This suggests that a higher proportion of breeding kittiwakes may be present in the offshore ornithology aerial survey study area during the late incubation and early chick rearing period of the breeding season when compared to common guillemot and razorbill, but also indicates that other areas of marine habitat (closer to the breeding colonies) will be used to a greater extent by breeding kittiwakes. A proportion of kittiwakes recorded in the offshore ornithology aerial survey study area are therefore anticipated to be non-breeding birds.
The baseline surveys recorded a more even spatial distribution of gannet across the offshore ornithology aerial survey study area than other species. Published utilisation distribution data suggests that the offshore ornithology aerial survey study area is within the home range (i.e. within the extent of the 50% utilisation distribution) of breeding birds from all UK and Republic of Ireland breeding colonies (Wakefield et al., 2013). This indicates that the majority of gannets recorded within the offshore ornithology aerial survey study area during the breeding season are likely to be breeding adults. Given the proximity of the offshore ornithology aerial survey study area to the Forth Islands SPA and the existing understanding of gannet foraging behaviour, it seems reasonable to assume that a high proportion of the breeding adult birds recorded in the offshore ornithology aerial survey study area during the breeding season will originate from the Forth Islands SPA.
Making appropriate and justifiable estimates of the proportions of non-breeding birds (particularly guillemot, razorbill and kittiwake) present within the offshore ornithology aerial survey study area during the breeding season will be a key focus of consultation with stakeholders, and the Array EIA Report and Report to Inform Appropriate Assessment (RIAA).
With respect to other species recorded by the baseline surveys during the generic breeding season, fulmar were recorded relatively frequently across the offshore ornithology aerial survey study area, with no discernible pattern to the spatial distribution of records. Arctic tern Sterna paradisaea were recorded during two months of the generic breeding season, though the timing of these records and the published mean maximum foraging range of this species of 25.7 km (+/- 14.8 km) (Woodward et al., 2019) indicates that these were likely birds on passage rather than foraging breeding adult birds from a nearby colony. Other species, including herring gull Larus argentatus, lesser black-backed gull Larus fuscus, great black backed gull Larus marinus, common gull Larus canus, common tern Sterna hirundo, great skua Stercorarius skua, little gull Hydrocoloeus minutus and Manx shearwater Puffinus puffinus, were recorded occasionally (less than five records) and distributed relatively uniformly across the offshore ornithology aerial survey study area at low densities.

Non-breeding season

Surveys in the offshore ornithology aerial survey study area indicate that during the generic non-breeding season (September to March), auks remained the most frequently recorded species group, where over half of all birds recorded during this period were guillemots. Other frequently recorded species (in descending order of frequency) were fulmar, puffin, kittiwake, gannet, razorbill and great black-backed gull. Species recorded infrequently (less than ten occasions during the generic non-breeding season) were herring gull, common gull and little auk (Alle alle).
All species were distributed relatively evenly across the offshore ornithology aerial survey study area. This change in the distribution of records when compared with the breeding season is likely explained by the known ecology of colonial seabirds. Outside the breeding season, breeding birds are not constrained by requirements to visit nests to incubate eggs or provision chicks. They are assumed to range more widely and to mix with birds of all age classes. In the case of many species, there is also mixing of birds from breeding colonies situated closer to the Array, with birds from breeding colonies in the UK and further afield.
Seaducks, divers, grebes, and waders, which spend the non-breeding season in the inner Firth of Forth and Firth of Tay in nationally important numbers, were absent from the offshore ornithology aerial survey study area and the area to the west of it during the first year of surveys. It is presumed that this is due to the distance between this area and the coast.
Very small numbers of some migratory species were recorded during the first year of surveys in the offshore ornithology aerial survey study area. Observations were limited to Arctic tern, common tern, little gull and Manx shearwater.
Passage movements are generally considered difficult to assess comparatively, using aerial survey methods. This is because they generally occur over relatively short periods and therefore may be missed by monthly surveys. Movements can also take place at high altitudes, and/or at night when detection is difficult. It is therefore considered possible that other seabird species such as petrels, in addition to non-seabird ornithology receptors, may use the offshore ornithology aerial survey study area during passage, but were not detected during the first 12 months of surveys. Many species are known to cross the North Sea in spring and autumn in large numbers.
Where possible, existing information in the literature will be used to characterise potential use of the offshore ornithology aerial survey study area by passage species.

Designated conservation sites for birds

A full screening of European designated sites with qualifying bird species has been undertaken and is detailed within the LSE Screening Report for the Array. The LSE Screening Report has been circulated for consultation alongside this Scoping Report. Relevant qualifying species of European designated sites screened into the ornithology assessment will be fully considered and assessed in the Array EIA Report. The assessment on the European designated sites themselves will be deferred to the RIAA.
Designated sites including SPAs, proposed SPAs (pSPAs) and Ramsar sites, will be identified through the process described for identification of the offshore ornithology regional study area. This will generate a ‘long-list’ of designated sites with potential connectivity to the offshore ornithology aerial survey study area. Breeding season connectivity with qualifying features of breeding seabird colony SPAs will be defined by species’ breeding season foraging ranges (using the mean maximum plus one standard deviation (Woodward et al., 2019)). Outside the breeding season, there is potential for connectivity with a greater range of qualifying features from breeding seabird colony SPAs than during the breeding season. Consideration of the potential for non-breeding season effects associated with the Array will be based upon information on Biologically Defined Minimum Population Scales (BDMPS) presented in Furness (2015) for all species other than guillemot and herring gull (NatureScot, 2021; Marine Scotland, 2022b). For both guillemot and herring gull, the breeding season foraging range will be used as these species are not considered to disperse as widely from the breeding areas compared to other seabird species during the non-breeding season (noting that for herring gull a correction, analogous to that used in the BDMPS approach, will also be applied to account for the influx of continental breeding birds to the wintering population on the east coast of the UK (Royal Haskoning DHV, 2022).
Based upon the above, there is potential for connectivity with a wide range of the breeding seabird colonies in the UK, particularly those on the east coast, and it is recognised that there will be many colonies, including designated sites, that could be impacted by both project alone effects and cumulative effects with other developments. The LSE Screening Report will provide full details of the relevant designated sites and features which are considered to have connectivity with the Array and will identify the potential effect pathways, so enabling the determination of sites and features for which LSE cannot be excluded. The subsequent RIAA will undertake the assessment for those sites and features for which LSE cannot be excluded.

Summary of first year of data from the baseline aerial survey programme

Based upon data from the first year of surveys, it is apparent that the following species comprise the vast majority of the birds occurring within the offshore ornithology aerial survey study area during both the breeding and non-breeding periods ( Table 6.15 Open ▸ ):

gannet;
kittiwake;
guillemot;
razorbill;
puffin; and
fulmar.

Other species tend to be recorded sporadically within the aerial survey data and at a level of abundance which is at least one order of magnitude less than that of the six species listed above. Subject to similar findings emerging from the second year of the aerial survey programme, it is therefore highly likely that the key species for the assessment will be included amongst the six species listed above.

Table 6.15: Occurrence and Abundance of Seabird Species Recorded in the Offshore Ornithology Aerial Survey Study Area During the First Year of Surveys1

Species	Breeding Season2		Non-Breeding Season2
Species	Number of Surveys in which Species Recorded	Mean Abundance (Number of Individuals per Survey) with 95% Confidence Interval3	Number of Surveys in which Species Recorded	Mean Abundance (Number of Individuals per Survey) with 95% Confidence Interval3
Gannet	7	2728 2038 - 3526	4	990 762 - 1216
Kittiwake	5	5585 3616 - 8167	7	596 277 - 1044
Guillemot	5	33666 23576 - 45515	7	9122 7257 - 11170
Razorbill	5	2665 1545 - 4016	6	206 111 - 312
Puffin	5	2161 1569 - 2875	6	786 585 - 1002
Fulmar	5	1572 1048 - 2282	7	1029 720 - 1415
Herring gull	5	46 4 - 126	3	12 1 - 26
Lesser black-backed gull	2	4 0 - 14	0	0 0 - 0
Great black-backed gull	1	2 0 - 6	4	81 45 - 128
Common gull	3	14 0 - 32	5	15 3 - 39
Little gull	1	2 0 - 6	0	0 0 - 0
Great skua	3	6 0 - 16	1	1 0 - 4
Arctic / common tern	2	454 128 - 911	0	0 0 - 0
Little auk	0	0 0 - 0	2	4 0 - 11
Manx shearwater	3	31 6 - 65	0	0 0 - 0
Wigeon Anas penelope	0	0 0 - 0	1	1 0 - 4

Notes:

1 – Data are presented without any apportioning of records identified to a broader group level to the species level, and without correction for availability bias.

2 – To avoid complications with half-months, and for the purpose of this preliminary presentation of the aerial survey data, the breeding season is defined as April to August for all species other than gannet for which it is defined as March to September.

3 – Values for the confidence intervals are derived by taking the average of these as calculated for the estimate from each individual survey (as opposed to calculating them on the basis of averaging across the mean estimates from each survey).

6.4.4. Designed In Measures

Full consideration will be given to the potential to minimise any impacts via the adoption of appropriate designed in measures. At this stage it is not possible to identify the range of designed in measures that may be adopted but examples of designed in measures that are likely to be considered, including how these could reduce potential for impact, ( Table 6.16 Open ▸ ) include:

the use of low order deflagration techniques during UXO clearance;
the incorporation of an appropriate air gap into wind turbine design to reduce collision rates between offshore ornithology receptors and operational turbines; and
optimised layout scenarios.

The options for adopting such designed in measures will be kept under review during the assessment process.

6.4.5. Potential Impacts After the Implementation of Designed in Measures

The impacts that have been scoped into the Array assessment are outlined in Table 6.16 Open ▸ together with a description of any additional supporting analyses (e.g. modelling) that will be required to enable a full assessment of the impacts. No impacts are proposed to be scoped out as a consequence of the designed in measures implemented.

Table 6.16: Impacts Proposed to be Scoped Into the Array Assessment for Offshore Ornithology. Project Phase Refers to Construction (C), Operation and Maintenance (O) and Decommissioning (D) Phase of the Array

Impact	Project Phase			Justification (including consideration of embedded mitigation measures)	Data Collection and Analysis Required to Characterise the Baseline Environment for the EIA	Summary of Proposed Approach to Assessment
Impact	C	O	D			Summary of Proposed Approach to Assessment
Temporary habitat loss and disturbance				The presence of vessels and construction or decommissioning works (including wet storage facilities) may temporarily disturb and/or displace offshore ornithology receptors present in the vicinity of works. This has the potential to affect productivity or survival.	Offshore ornithology abundance estimates from baseline aerial surveys will be used to estimate the numbers of birds potentially impacted.	Best practice methodologies and latest published information will be drawn upon to estimate potential disturbance distances and rates for key species.
Indirect Impacts from construction/decommissioning noise				The reduction or disruption of prey availability may cause reduced energy intake in offshore ornithology receptors, which could potentially affect productivity or survival.	The use of site-specific baseline data is not proposed.	Potential impacts will be estimated using best practice methodologies and latest published information.
Indirect impacts from UXO clearance				The potential for physical injury and death to diving offshore ornithology receptors below water at time of detonation. The reduction or disruption of prey availability due to detonations may cause reduced energy intake affecting productivity or survival of offshore ornithology receptors. This will be mitigated by low-order clearance.	The use of site-specific baseline data is not proposed.	Potential impacts will be estimated using best practice methodologies and latest published information.
Disturbance and displacement from the physical presence of wind turbines and maintenance activities				The presence of operational wind turbines and the maintenance activities associated with their operation may disturb offshore ornithology receptors and displace them from their foraging or resting areas. This has the potential to affect productivity or survival.	Offshore ornithology abundance estimates from baseline aerial surveys will be used to estimate the numbers of birds potentially impacted.	Potential impacts will be estimated using best practice methodologies (e.g. a matrix-based approach for all species scoped into assessment, and potentially SeaBORD for relevant species during specific times of year). For any population for which it is required, Population Viability Analysis (PVA) will be used to assess the consequences of predicted impacts at the population level.
Barrier to movement				The presence of operational wind turbines may result in additional energy and/or time expenditure as migrating or commuting offshore ornithology receptors fly longer distances either over, under, or around the wind farm. This has the potential to affect productivity or survival.	Offshore ornithology abundance estimates from baseline aerial surveys will be used to estimate the numbers of birds potentially impacted.	Potential impacts will be estimated using best practice methodologies (e.g. a matrix-based approach for all species scoped into assessment, and potentially SeaBORD for relevant species during specific times of year). For any population for which it is required, PVA will be used to assess the consequences of predicted impacts at the population level.
Collision with wind turbines				Collisions between offshore ornithology receptors will result in direct mortality. This will result in reductions in seabird populations and/or breeding success. This will be mitigated by the selection of an appropriate air gap between the sea surface and the lowest part of the rotor swept area. This air gap has not yet been selected but will be informed by the results of the preliminary Collision Risk Model (CRM).	Offshore ornithology abundance estimates from baseline aerial surveys will be used to estimate the numbers of birds potentially impacted.	Potential impacts will be estimated using best practice methodology (e.g. stochastic CRM (sCRM)). For any population for which it is required, PVA will be used to assess the consequences of predicted impacts at the population level.
Changes to prey availability				Indirect impacts on seabirds may occur as a result of changes in prey distribution, availability or abundance, caused by construction/decommissioning activities that disturb the seabed (and cause increased SSCs) or increase subsea noise levels.	Offshore ornithology abundance estimates from baseline aerial surveys will be used to estimate the numbers of birds potentially impacted.	Best practice methodologies and latest published information and other available evidence will be drawn upon to estimate potential effects on key species.
Entanglement				With the advent of floating offshore wind, the potential for entanglement of diving seabirds with floating foundations during the operation and maintenance period has been raised.	Offshore ornithology abundance estimates from baseline aerial surveys will be used to estimate the numbers of birds potentially impacted.	Best practice methodologies and latest published information and other available evidence will be drawn upon to estimate potential effects on key species.

6.4.6. Relevant Consultations

A summary of the details of the consultations with relevant stakeholders and Statutory Nature Conservation Bodies (SNCBs) undertaken to date is presented in Table 6.17 Open ▸ .

Table 6.17: Summary of Key Consultation on the Scoping Assessment for the Array

Date	Consultee	Type of Consultation	Summary of Consultation	Where Addressed?
14 November 2022	MS-LOT, MSS, NatureScot and RSPB	Scoping workshop	NatureScot advised use of the Marine Renewables Strategic Environmental Assessment (MRSea) package to derive bird densities from the baseline aerial survey data (i.e. model-based), as opposed to using design-based approaches. However, based on their understanding of the different approaches and of recent experience in other projects, the Applicant considers that design-based approaches are likely to be more appropriate.	The proposed approach (and associated rationale) to deriving bird densities for use in the EIA is outlined in section 6.4.7.
			NatureScot requested access to end of year survey reports, which they think may be useful in determining what has happened to bird populations as a result of HPAI.	Summary data on preliminary bird abundance from the first year of baseline surveys are presented in Table 6.15 Open ▸ . Further analyses of baseline data to estimate densities and abundance will not be available until after completion of the survey programme (with these expected to be available by June 2023). The report detailing these data will be made available to stakeholders.
			The Applicant requested information on when NatureScot guidance on the implications of the HPAI outbreak for offshore wind farm assessments would become available, with NatureScot confirming that work on this is ongoing and that it would be made available as soon as possible.	The requirement for consultation on HPAI is highlighted in sections 6.4.7 and 6.4.10.
			NatureScot indicated that publication of the Apportioning Guidance Note may be slightly later than for other guidance notes. The Applicant indicated their interest in accessing this guidance.	The proposed approach to undertaking apportioning is outlined in section 6.4.7.
			The Applicant highlighted the need for guidance to be available on CRM approaches, with NatureScot agreeing that the approach outlined by the Applicant is what they were expecting. NatureScot stated that they are currently working on the timings for releasing the guidance. The Applicant indicated that further consultation on this will be important following receipt of the Scoping Opinion.	The proposed approach to undertaking CRMs is outlined in section 6.4.7.
			The Applicant emphasised the importance of maintaining good communications with key stakeholders, particularly in the context of the impending emergence of nine different guidance notes that will have critical importance to the assessment.	Specific issues on which further, focussed, engagement is considered to be essential are outlined in section 6.4.10.

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