6.3.5. Designed In MeasuresDesigned In Measures

The following designed in measures have been considered in the identification of potential impacts that have been scoped into the Array assessment, including how these can reduce potential for impact ( Table 6.13 Open ▸ ):

the development of and adherence to an appropriate Code of Construction Practice (CoCP);
the development of and adherence to an EMP (including a Marine Pollution Contingency Plan (MPCP));
the development of and adherence to a VMP; or equivalent to be consulted upon with stakeholders post-consent;
the development of and adherence to a Marine Mammal Mitigation Plan (MMMP) to outline the additional mitigation to be implemented for piling and UXO clearance;
the development of and adherence to a Piling Strategy (or equivalent, after consultation with stakeholders) which will set out the mitigation measures including soft-start and ramp-up measures;
implementation of soft-start and ramp-up measures for piling and UXO clearance;
use of low order deflagration (ideally, and where possible) for UXO clearance; and
implementation of a Decommissioning Programme.

The significance of effects on marine mammal receptors will inform the extent of additional mitigation required. This significance will be assessed using the best available evidence (such as information from other offshore wind farms) and will be consulted and agreed upon with the statutory consultees throughout the consultation process.

6.3.6. Relevant ConsultationsRelevant Consultations

A summary of the key points of agreement with relevant stakeholders and Statutory Nature Conservation Bodies (SNCBs) during the Array Scoping workshop undertaken in November 2022 is presented in Table 6.12 Open ▸ .

Table 6.12: Summary of Key Consultation on the Scoping Assessment for the Array

Date	Consultee(s)	Type of Consultation	Summary of Consultation	Where Addressed
17 November 2022	NatureScot, MS-LOT, MSS	Scoping workshop	The requirement for further information regarding scoping out EMFs and operational noise from turbines was discussed. In addition, scoping out impacts due to UXO and geophysical and other pre-construction surveys was agreed upon due to the alternate licenses to be sought for these activities.	Table 6.14 Open ▸
17 November 2022	NatureScot, MS-LOT, MSS	Scoping workshop	Scoping in effects on marine mammals due to operational noise of anchor mooring lines was discussed, as was the inclusion of both primary and secondary entanglement in the scoping assessment. Finally, the potential to scope out injury to marine mammals due to collision with vessels was proposed, however it has been decided to scope in this potential impact during this revision whilst feedback is sought from stakeholders as agreement was not reached during the pre-Scoping workshop.	Table 6.13 Open ▸

6.3.7. Potential Impacts After the Implementation of Designed in MeasuresPotential Impacts After the Implementation of Designed in Measures

Table 6.13 Open ▸ outlines the impacts which have been scoped into the Array assessment alongside a description of any additional data collection (e.g. site-specific surveys) and/or supporting analyses (e.g. modelling) that will be required to enable a full assessment of the impacts.
Table 6.14 Open ▸ describes the potential impacts to marine mammals that have been scoped out of the assessment presently.

Table 6.13: Impacts Proposed to be Scoped In to the Array Assessment for Marine Mammals. Project Phase Refers to Construction (C), Operation and Maintenance (O) and Decommissioning (D) Phase of the Array

Impact	Project Phase			Justification (including consideration of designed in 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
Injury and disturbance from subsea noise generated during UXO clearance				Marine mammals are sensitive to increased subsea noise generated during UXO clearance. Although UXO detonation works will be consented under a separate licensing regime, impacts from the works are scoped in here to ensure a pragmatic assessment of impacts to marine mammals is carried out. This separate license application will include designed in measures, such as the use of low order deflagration for UXO clearance wherever possible, and the development of a MMMP that is informed by the most recent guidance (JNCC, 2010b) and the outcomes of subsea noise modelling. Within the MMMP, additional mitigation will be outlined as required, such as the use of a defined mitigation zone, MMOs, PAM, ADDs and soft-start charges.	Confirmation on the number and sizes of UXOs to be cleared, and their associated charges, within the site boundary. Aerial survey data will be used to calculate density estimates, where data allows, for each species within the impact footprint.	A detailed noise modelling assessment will be undertaken to quantitively assess the risk of auditory injury and disturbance due to UXO clearance and to define a sufficient mitigation zone.
Injury and disturbance from subsea noise generated during piling				Marine mammals are sensitive to increased subsea noise generated during piling. Designed in measures include the development of piling soft-start and ramp up measures, a defined mitigation zone based on the noise modelling assessment and the development of an MMMP. Within the MMMP, additional mitigation will be outlined, such as the use of Marine Mammal Observers (MMOs), Passive Acoustic Monitoring (PAM), and ADDs.	Site-specific digital aerial survey data will be used to calculate density estimates, where data allows, for each species within the impact footprint. See Appendix 9 for full details of site-specific surveys.	A detailed noise modelling assessment will be undertaken to quantitively assess the risk of auditory injury and disturbance and to define a sufficient mitigation zone. Specific modelling parameters are unavailable at the time of writing, however this modelling will likely investigate scenarios such as the potential numbers of piling locations and the two furthest piling locations. The most recent guidance and thresholds presented in Southall et al. (2019) will be used to assess the risk of permanent auditory injury, in terms of PTS. This risk will be based on the dual metric approach: cumulative sound exposure level (SELCUM) and peak sound exposure level (SPLPEAK). The assessment of disturbance will be based on the good practice methodology available at the time and the most recent guidance documents, such as those provided by the JNCC. Noise contours at appropriate intervals will likely be generated from the noise modelling and overlain on species density surfaces to predict the number of animals potentially affected. To understand the ecological consequences of piling on marine mammals, the assessment will also use population modelling (iPCoD) and the potential for short-term and long term effects.
Disturbance due to vessel use and vessel activities				The impact of vessel use and vessel activities (such as dredging, rock placement, and trenching within the construction phase, operation and maintenance phase, and decommissioning activities) may result in behavioural disturbance and/or displacement of marine mammals. The designed in measure for this impact is the implementation and adherence to a VMP, and a decommissioning plan.	Not applicable for this impact	Comparative noise modelling for non-piling activities that also produce noise will be undertaken to inform a qualitative assessment of non-piling noise producing activities, such as geophysical surveying, rock placement and vessel movement.
Injury due to collision with vessels				There is likely to be increased vessel traffic during the construction, operation and maintenance, and decommissioning stages, which could increase the risk of collisions with marine mammals. The designed in measure for this impact is the implementation and adherence to a VMP (or equivalent).	Not applicable for this impact	A qualitative assessment will be undertaken, based on the best available and most recent literature at the time of writing.
Effects on marine mammals due to altered prey availability				Changes in abundance and distribution of prey species (such as fish, crustaceans, cephalopods, etc.) may occur due to activities in the construction, operation and maintenance, and decommissioning phases. These changes may affect the ability of marine mammals to forage. There are no designed in measures applicable to this impact.	Not applicable for this impact	There will be no specific modelling required for this impact, although the assessment will be based on the results of the subsea noise modelling assessment, Physical Processes assessment, and the resulting impact assessment carried out for fish and shellfish receptors.
Effects on marine mammals due to entanglement associated with the Array	×		×	The presence of anchor mooring lines may cause entanglement of animals in itself (primary entanglement), and lost or discarded fishing gear and other marine debris have the potential to become snagged and cause secondary entanglement of marine wildlife. Floating offshore wind is in its infancy so there is no data currently available to assess this impact. Therefore, both primary and secondary entanglement will be scoped in. There are no designed in measures relevant for this impact.	Not applicable for this impact	Desk-based study of data as it emerges to undertake a qualitative assessment.
Injury and disturbance due to operational noise from anchor mooring lines				Subsea noise produced by anchor mooring lines in the operation and maintenance phase has the potential to cause injury and disturbance to marine mammals. This impact is scoped in as a precaution due to the paucity of information regarding the levels of subsea noise produced by the anchor mooring lines of floating offshore wind turbines. There are no designed in measures relevant for this impact.	Not applicable for this impact	Subsea noise modelling to determine potential elevations in noise during operation.

Table 6.14: Impacts Proposed to be Scoped Out of the Array Assessment for Marine Mammals

Impact	Justification
Construction
Disturbance due to pre-construction and geophysical surveys	Pre-construction surveys (including geophysical surveys) during the construction phase, and annual geophysical surveys conducted during the operation and maintenance phase may result in behavioural disturbance and displacement of marine mammals. However, in order to achieve a proportionate EIA, this impact will not be considered further within the EIA as full geophysical and geotechnical surveys are expected to be completed in 2023 and it will be subject to a separate license. The separate license application will include designed in measures for this impact, such as the development of an MMMP following recent JNCC guidance (JNCC, 2017). The MMMP will contain additional mitigation measures, such as mitigation zones, MMOs, PAM, ADDs and soft-start charges.
Effects on marine mammals due to accidental release of pollutants	The impact of pollution released during accidental spills and contaminant releases could reduce species survival rates, either as a result of direct mortality of marine mammals or through a reduction in prey availability (scoped in). Designed in measures for this impact are the development and adherence to an EMP, including a MPCP, and an appropriate CoCP during the construction phase. With these measures in place and based on evidence from nearby Berwick Bank Offshore Wind Farm consent application (SSER, 2022), it is considered unlikely that a major incident affecting any species at population level will occur. SSER (2022) predicted that any impact would be of a local spatial scale, short term, intermittent and medium reversibility within the context of regional populations, and therefore not significant in EIA terms. This is considered to be applicable to the Array, where construction, operation and maintenance, and decommissioning will be of a comparable scale and within close proximity. Therefore, it is proposed that this impact is scoped out of the EIA.
Effects on marine mammals due to increased SSC and associated deposition	Increased SSC and associated deposition can disrupt water quality, which could have direct and indirect effects on marine mammals. Indirect impacts could include negative effects on prey species and reduced prey availability (scoped in). Direct impacts would include impaired visibility, thereby reducing foraging ability. However, marine mammals are known to forage in areas where water conditions are turbid and visibility is low. As harbour porpoises and harbour seals have been observed foraging in these conditions (Pierpoint, 2008; Marubini et al., 2009; Hastie et al., 2016), it is unlikely that low light levels, increased turbidity and murky water associated with increased SSC will adversely impact marine mammal foraging ability. Although these conditions may compromise visual ability, marine mammals are able to use other senses to navigate their surroundings. For example, seals can detect water movements and hydrodynamic trails with their mystacial vibrissae (i.e., whiskers; Dehnhardt et al., 2001; Grant et al., 2013) and odontocetes are well known for their use of echolocation to detect their surroundings and forage. Increased SSC and its associated effects on water quality generated during the construction and decommissioning stages of the Array are expected to have a localised maximum impact range. Sediments are likely to dissipate within one tidal cycle. Overall, the ZoI of increased SSC and associated deposition will be small, particularly in the context of the regional marine mammal study area, the duration of effects will be short term, and marine mammal receptors are not considered to be sensitive to increases in SSC. Therefore, it is proposed that this impact is scoped out of the EIA.
Operation and Maintenance
Effects on marine mammals due to accidental release of pollutants	As above for the construction phase.
Effects on marine mammals due to EMF from subsea electrical cabling	While the effects of EMF on fish and shellfish receptors are documented, there is no evidence of EMF related to offshore wind farms having any negative impact on marine mammals (Copping, 2018; Copping et al., 2020). Furthermore, there are no regulatory thresholds or guidelines that define acceptable levels of EMF emissions into the marine environment (Copping et al., 2020). There is no evidence that seals can detect or respond to EMF, however some cetacean species, may be sensitive and/or able to detect variations in magnetic fields (Normandeau, 2011; Czech-Damal et al., 2012; Hüttner et al., 2022). Until recently, the Guiana dolphin Sotalia guianensis was the only marine mammal species demonstrated to respond to EMFs (Czech-Damal et al., 2012, 2013). The Guiana dolphin possesses an electroreceptive system, which involves vibrissal crypts on their rostrum to detect weak electrical fields generated by their prey fish (Czech-Damal et al., 2012). As the Guiana dolphin only occurs in Central and South American waters, it is not present within the scope of this assessment. However, recent experimental evidence suggests that adult bottlenose dolphins possess many basic morphological similarities in their vibrissal crypts to Guiana dolphins and can perceive as equally low electrical fields (Hüttner et al., 2022). The authors suggest that bottlenose dolphins use electroreception to detect benthic prey at short ranges and suggest that as this ability has now been observed in two dolphin species, it may be widespread within odontocetes (Hüttner et al., 2022). However, the effects of EMFs from subsea cabling are attenuate below background levels within metres from the cable itself (Hutchinson, et al., 2021). As marine mammals have wide spatial distribution and are variable within the water column, the impacts (if any) from EMF will be minimal. Therefore, it is proposed that this impact is scoped out of the EIA.
Injury and disturbance due to operational noise from turbines	Previous studies on fixed foundation wind turbines have demonstrated that operational noise produced by turbines will have negligible effects on marine mammals (Teilmann et al., 2006a, 2006b; Cefas, 2010; Brasseur et al., 2012; Tougaard et al., 2020) and the noise generated has been demonstrated to be much lower than levels associated with construction activities (such as piling; Madsen et al., 2006). There is less information available on the operational noise levels of floating offshore wind turbines, however any effects on marine mammals are likely to be minimal as noise generated from the turbines is likely to be of low frequency and at low levels (Farr et al., 2021). Similarly, a subsea noise desk study for the Hywind Scotland pilot park of floating offshore wind turbines concluded that injury and disturbance due to operational noise of the turbines was unlikely to occur (Xodus, 2015). Therefore, it is proposed that this impact is scoped out of the EIA.
Disturbance due to geophysical surveys	As above for the construction phase.
Decommissioning
Effects on marine mammals due to accidental release of pollutants	As above for the construction phase.
Effects on marine mammals due to increased SSC and associated deposition	As above for the construction phase.

6.3.8. Proposed Approach to the Environmental Impact Assessment Proposed Approach to the Environmental Impact Assessment

The methodology set out in section 4 will be followed when preparing the marine mammal chapter of the Array EIA Report. The following guidance documents will also be considered with regard to marine mammals:

CIEEM guidelines for marine and coastal ecological impact assessment in Britain and Ireland (CIEEM, 2019);
European Union Guidance on wind energy developments and Natura 2000 and EU Nature legislation (European Commission (EC), 2010, 2021);
Oslo Paris Convention (OSPAR) guidance on environmental considerations for offshore wind farm development (OSPAR, 2008); and
The marine mammal noise exposure criteria recommended in Southall et al., (2019); and
JNCC guidelines for minimising the risk of injury to marine mammals from piling noise (JNCC, 2010a).

A detailed quantitative subsea noise assessment will be used to inform the impact assessment. The subsea noise assessment will include UXO clearance, pile driving, rock placement and vessel noise. This assessment will include PTS and behavioural disturbance with the risk of injury based on a dual metric approach: SELcum and peak SPLpeak. In order to assess the SELcum criterion, the predictions of received sound level over 24 hours are frequency weighted, to reflect the hearing sensitivity of each functional hearing group. The SPLpeak criterion will be used for unweighted received sound level. Good practice methodology will be followed during the assessment of disturbance, which, where possible, will include consideration of species-specific dose-response curves. Noise contours at appropriate intervals will be generated by the noise modelling. These contours will be overlain on species density surfaces to predict the number of animals potentially affected.
At this stage, the species densities surfaces and agreement of correction factors for availability bias will be discussed with relevant stakeholders as part of consultation process.

6.3.9. Potential Cumulative EffectsPotential Cumulative Effects

The key cumulative effect is likely to come from subsea noise produced by piling during the construction phase. A range of realistic cumulative subsea noise scenarios will be assessed in the CEA. This will be based on desk-based resources, communication with other developers (where possible), and consultation and agreement with stakeholders and regulators.
The approach to the CEA for marine mammal receptors will be holistic and combine all potential subsea noise sources:

piling;
UXO clearance;
disturbance from vessels; and
any other offshore construction that is planned within the relevant MUs for each species (such as rock placement).

Realistic scenarios for the CEA for subsea noise will be based on impacts that do not already occur throughout the baseline environment. For example, the impacts of commercial fishing and shipping will not be considered in the CEA as they already occur throughout the baseline environment and are therefore accounted for in the abundance and density estimates of the target marine mammal species.
The CEA will follow the approach outlined in section 4.3.7.

6.3.10. Potential Transboundary ImpactsPotential Transboundary Impacts

Appendix 3 presents the transboundary impacts screening which has been carried out for the Array. This screening exercise identified that there is no potential for significant transboundary impacts upon marine mammals from construction, operational and maintenance, and decommissioning impacts of the Array.

6.3.11. Scoping Questions to ConsulteesScoping Questions to Consultees

Do you agree with the study areas defined for marine mammal ecology?
Do you agree that the existing data available to describe the marine mammal baseline remains sufficient to describe the physical environment in relation to the Array? Are there any further desktop datasets which you would recommend are included?
Do you agree that the designed in measures described provides a suitable means for managing and mitigating the potential effects of the Array on the marine mammal receptors?
Do you agree that the impacts listed in Table 6.13 Open ▸ should be scoped in to the impact assessment for marine mammal receptors?
Do you agree that the impacts listed in Table 6.14 Open ▸ should be scoped out of the Array EIA Report for marine mammals?

6.3.12. Next StepsNext Steps

This section provides a summary of suggested topic specific next steps that will be undertaken throughout the EIA process:

develop the approach and parameters to be used in subsea noise modelling with stakeholders, including:

– modelling locations;

– pile types;

– maximum hammer energy and duration;

– duration of soft start and ramp up energies;

– number of piles installed per day;

– occurrence of concurrent piling (i.e. more than one piling operation in the same day); and

– number of, size of and associated clearance charges of UXO.

Additionally, the durations and requirements of additional mitigation measures, such as soft-start and ramp-up measures, and the use of MMOs, PAM and ADDs, will be discussed with stakeholders and informed by the relevant guidance (JNCC, 2010a, 2010b, 2017).
The approach to these will be discussed as part of the post-Scoping consultation process as described in the dSEP (Appendix 1).

6.4. Offshore Ornithology Offshore Ornithology

6.4.1. IntroductionIntroduction

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 AreaStudy 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).

Map

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

6.4.3. Baseline EnvironmentBaseline 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.

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