Displacement/barrier effects – operation and maintenance

1577. As described in annex E of Offshore EIA Report, volume 3, appendix 11.6, estimates of breeding season displacement mortality which had been attributed to the Fowlsheugh SPA razorbill population were extracted from the existing assessments for offshore wind farms that are in planning, consented, under construction or in operation. As for the potential displacement mortality estimated for the Proposed Development, the mortality attributed to the SPA population from other offshore wind farms was estimated using the SNCB matrix approach, with details on the displacement and mortality rates that had been applied being available in each case. Thus, it was possible to adjust the estimated mortalities from each of the other projects to align with the displacement and mortality rates on which the Scoping and Developer Approaches are based.
1578. For the non-breeding periods, razorbill numbers associated with other offshore wind farms that are in planning, consented, under construction or in operation were extracted for each of the relevant seasonal periods from the cumulative totals collated for the East Anglia TWO and East Anglia ONE North submissions (MacArthur Green and Royal HaskoningDHV 2021, see annex D of Offshore EIA Report, volume 3, appendix 11.6 for more details). The cumulative numbers for each of the non-breeding periods were apportioned to the Fowlsheugh SPA razorbill population according to the BDMPS approach (Furness 2015), with the subsequent displacement mortality calculated according to the displacement and mortality rates appropriate to each of the Scoping and Developer Approaches (Table 5.101). This was done separately for all of the other UK North Sea wind farms and for the subset represented by the other Forth and Tay wind farms.

Table 5.103: Estimated Annual Mortality of Fowlsheugh SPA Razorbills as a Result of Displacement from the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach, In-Combination with other Forth and Tay Wind Farms and UK North Sea Wind Farms

1579. The potential mortality resulting from the predicted displacement effects associated with the Proposed Development in-combination with the other Forth and Tay wind farms represents an approximate fourfold increase in that predicted for the Proposed Development alone (for both Developer and Scoping Approaches), whilst for the Proposed Development in-combination with the other UK North Sea wind farms there is an almost fivefold increase in the predicted mortality compared to that for the Proposed Development alone (Tables 5.101 and 5.103). For all scenarios the predicted mortality is concentrated in the breeding season. Thus, for the Proposed Development in-combination with the other Forth and Tay wind farms, 91 – 97% of the predicted mortality is attributed to the breeding season, whilst for the Proposed Development in-combination with the other UK North Sea wind farms 69 – 87% of the predicted mortality is attributed to the breeding season (with the percentages being higher for the Scoping Approach than the Developer Approach).
1580. For the Proposed Development in-combination with the other Forth and Tay wind farms, the additional annual mortality of adult razorbills from the Fowlsheugh SPA population predicted due to displacement represents 0.09% of the current adult breeding population at this colony (i.e. 17,817 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach, and between approximately 0.29 – 0.49% of this population as determined by the lower and upper estimates from the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.090 – see Table 2.19 in the Offshore EIA Report, volume 3, appendix 11.6), the estimates of adult displacement mortality equate to an increase of 0.9% for the Developer Approach and of 3.2 – 5.5% for the lower and upper estimates from the Scoping Approach.
1581. For the Proposed Development in-combination with the other UK North Sea wind farms, the additional annual mortality of adult razorbills from the Fowlsheugh SPA population predicted due to displacement represents 0.12% of the current adult breeding population at this colony as determined by the Developer Approach, and between approximately 0.32 – 0.60% of the current adult breeding population at this colony as determined by the lower and upper estimates from the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population, the estimates of adult displacement mortality equate to an increase of 1.3% for the Developer Approach and of 3.6 – 6.7% for the lower and upper estimates from the Scoping Approach.
1582. The potential levels of impact on the Fowlsheugh SPA razorbill population resulting from the mortality predicted from displacement and barrier effects associated with the Proposed Development in-combination with other wind farms in the Forth and Tay or in-combination with other wind farms in the UK North Sea during the operation and maintenance phase are considered in more detail below in the Effects In-Combination: Population-Level Impacts section. This presents the outputs from PVAs of the potential effects of predicted displacement mortality on the SPA population.

In-combination: population-level impacts

1583. As for the Proposed Development alone, PVA was undertaken on the mortality to the adult and immature age classes predicted due to the displacement effects associated with the Proposed Development in-combination with the other Forth and Tay wind farms and the Proposed Development in-combination with the other UK North Sea wind farms. This was on the basis of the potential mortality as determined by both the Scoping and Developer Approaches (see Table 5.103 above).
1584. The approach to the PVA and the metrics used to summarise the PVA outputs are as described for the Proposed Development alone (see Project Alone: Population-Level Impacts section above).

Table 5.104: Projected 35 Year Population Sizes and Associated PVA Metrics for the Fowlsheugh SPA Razorbill Population Under Different Impact Scenarios for the Proposed Development In-Combination with the other Forth and Tay Wind Farms

Table 5.105: Projected 35 Year Population Sizes and Associated PVA Metrics for the Fowlsheugh SPA Razorbill Population Under Different Impact Scenarios for the Proposed Development In-Combination with the other UK North Sea Wind Farms

1585. Given that the in-combination effects are inevitably greater than those for the Proposed Development alone, the PVA metrics for the Proposed Development in-combination with either the other Forth and Tay wind farms or the other UK North Sea wind farms suggest greater population-level impacts than as predicted for the Proposed Development alone (compare Table 5.102 with Tables 5.104 and 5.105). However, on the basis of the effects as determined by the Developer Approach, the predicted levels of impact remain relatively small. Thus, the CPS value for the Proposed Development in-combination with the other UK North Sea wind farms indicates that the SPA population size would be reduced by 5% after 35 years relative to that in the absence of any wind farm effects (Table 5.105). The centile value of 46.0 indicates a considerable overlap in the distributions of the predicted impacted and un-impacted population sizes and, hence, a high likelihood of the impacted population being of a similar size to the un-impacted population after 35 years. The PVA metrics for the Proposed Development in-combination with the other Forth and Tay wind farms indicate lower levels of impact (as determined by the Developer Approach), as would be expected from the lower predicted mortalities (Table 5.104).
1586. The predicted levels of impact as determined by the Scoping Approach are considerably greater, with the CPS values indicating reductions of 12 – 19% and of 13 – 22% in the size of the SPA population after 35 years (relative to that in the absence of any wind farm effects) for the other Forth and Tay in-combination scenario and the other UK North Sea in-combination scenario, respectively (Tables 5.104 and 5.105). The centile values range from 30.9 – 38.8 for the Proposed Development in-combination with the other Forth and Tay wind farms and from 27.7 – 37.6 for the Proposed Development in-combination with the other UK North Sea wind farms. These suggest a moderate overlap in the distributions of the predicted impacted and un-impacted population sizes and, hence, overall a reasonable likelihood of the impacted population being similar in size to the un-impacted population after 35 years.

In-combination: conclusion

1587. On the basis of the Developer Approach, it is considered that the potential effects from the Proposed Development in-combination with the other Forth and Tay wind farms or the other UK North Sea wind farms would not result in an adverse effect on the Fowlsheugh SPA razorbill population. The predicted population-level impacts are small, whilst there remains a high likelihood of the population being of a similar size to that which would occur in the absence of the Proposed Development after 35 years. Furthermore, this level of impact is within the context of an assessment which incorporates high levels of precaution and a population for which the documented, long-term, trend has been relatively stable over the long-term (but with a recent marked increase) and which is considered to be in ‘favourable maintained’ condition.
1588. For the Scoping Approach, the predicted levels of impact are markedly greater. For the upper, but not lower, range of effects encompassed by the Scoping Approach it is considered that the possibility of an adverse effect on the SPA population cannot be excluded. This conclusion is considered to apply to the effects from the Proposed Development in-combination with either the other Forth and Tay wind farms or the other UK North Sea wind farms. However, as detailed above, it is also considered that the displacement and mortality rates used in the Scoping Approach are overly precautionary and are not supported by the available evidence (volume 3, appendix 11.4, annex G of the Offshore EIA Report). Therefore, it is considered that greater weight should be given to the conclusions as determined by the Developer Approach.

Assessment for the breeding seabird assemblage

1589. The breeding seabird assemblage for the Fowlsheugh SPA is a qualifying feature on the basis of the SPA supporting in excess of 20,000 individual seabirds (with the citation also noting that the SPA regularly supports 145,000 seabirds). Razorbill, guillemot, kittiwake and herring gull comprise four of the five species identified in the citation as having populations which are considered to be of European or national importance and which contribute to the Fowlsheugh SPA breeding seabird assemblage (the fifth such species being fulmar, for which no LSE was determined in relation to the Proposed Development – HRA Stage One Screening Report).
1590. Potential impacts of the Proposed Development alone and in-combination with either the other Forth and Tay or the other UK North Sea wind farms on the breeding seabird assemblage for the SPA could arise via effects on the individual species within the assemblage feature. For the Developer Approach, the assessments undertaken above identify the potential for an adverse effect only on the SPA kittiwake population in relation to both of the in-combination scenarios. For the Scoping Approach, the assessments undertaken above identify the potential for adverse effects on the SPA guillemot population for the project alone and for the SPA kittiwake, guillemot and razorbill populations in relation to both of the in-combination scenarios.
1591. Thus, for the Proposed Development alone, the potential for an adverse effect is identified only for the SPA guillemot population as determined by the Scoping Approach (but not as determined by the Developer Approach). Given the range of species present within the SPA seabird assemblage and their relative abundances, it is considered that the potential adverse effect on the SPA guillemot population (as determined by the Scoping Approach) would not be sufficient to result in a subsequent adverse effect on the seabird assemblage.
1592. For the in-combination scenarios as determined by the Developer Approach, the potential for an adverse effect is identified only in relation to the SPA kittiwake population. The Fowlsheugh SPA kittiwake population is currently two and half to three times larger than those at the St Abb’s Head to Fast Castle SPA and at the Forth Islands SPA. Therefore, despite the documented long-term decline in this population, it is not considered that the in-combination effects are likely to lead to a risk of this population being lost from the breeding seabird assemblage at the Fowlsheugh SPA (in contrast to the conclusions reached for the St Abb’s Head to Fast Castle SPA and Forth Islands SPA). Also, given the range of species present within the SPA seabird assemblage and their relative abundances, it is considered that the potential adverse effect on the SPA kittiwake population would not be sufficient to result in a subsequent adverse effect on the seabird assemblage.
1593. For the in-combination scenarios as determined by the Scoping Approach, it is also the case that the predicted impacts on the SPA kittiwake are not considered likely to lead to a risk of this population being lost from the breeding seabird assemblage at the Fowlsheugh SPA. However, it is considered conceivable that the combined predicted in-combination impacts on the SPA kittiwake, guillemot and razorbill populations are such as to represent a risk of reducing the total number of individual seabirds present in the assemblage to a level that could represent an adverse effect on this qualifying feature. This conclusion should be considered within the context of the high levels of precaution incorporated within the assessment, with these being outlined above in the sections on the contributory SPA populations of the Fowlsheugh SPA breeding seabird assemblage.
1594. Given the above, it is concluded that there is the potential for an adverse effect on the Fowlsheugh SPA breeding seabird assemblage in relation to the Proposed Development in-combination with (i) the other Forth and Tay wind farms and (ii) the other UK North Sea wind farms, as determined by the Scoping Approach. No potential for an adverse effect on the SPA breeding seabird assemblage is identified in relation to the Proposed Development alone (irrespective of whether determined by the Developer or Scoping Approaches) or in relation to the Proposed Development in-combination with (i) the other Forth and Tay wind farms and (ii) the other UK North Sea wind farms, as determined by the Developer Approach.

Site conclusion

Developer approach

1595. It is concluded that the possibility of an adverse effect cannot be discounted for the Fowlsheugh SPA population of breeding kittiwake (noting this species is a named component of the seabird assemblage feature only). For the kittiwake population, the potential for an adverse effect arises from the Proposed Development in-combination with either (i) the other Forth and Tay wind farms or (ii) the other UK North Sea wind farms. The predicted impacts on the SPA kittiwake population are not considered to be sufficient to lead to a potential adverse effect on the breeding seabird assemblage feature.
1596. Consequently, it is concluded that an Adverse Effects on Integrity of the Fowlsheugh SPA cannot be excluded due to effects of the Proposed Development in-combination with other plans and projects.

Scoping approach

1597. It is concluded that the possibility of adverse effects cannot be discounted for the Fowlsheugh SPA populations of breeding kittiwake, guillemot and razorbill (noting these species are named components of the seabird assemblage feature only), as well as the breeding seabird assemblage qualifying feature (due to the impacts on kittiwake, guillemot and razorbill components only). For the guillemot population, the potential for an adverse effect arises from the Proposed Development alone and the Proposed Development in-combination with either (i) the other Forth and Tay wind farms or (ii) the other UK North Sea wind farms. For the kittiwake and razorbill populations, and the breeding seabird assemblage feature, the potential for an adverse effect is in relation to the effects of the Proposed Development in-combination with either (i) the other Forth and Tay wind farms or (ii) the other UK North Sea wind farms.
1598. For the Proposed Development alone, the predicted impacts on the SPA guillemot population are not considered to be sufficient to lead to a potential adverse effect on the breeding seabird assemblage feature, whilst the potential for an adverse effect on the breeding seabird assemblage feature in relation to the in-combination scenarios is a direct consequence of the potential in-combination effects on the kittiwake, guillemot and razorbill populations.
1599. Consequently, it is concluded that an Adverse Effects on Integrity of the Fowlsheugh SPA cannot be excluded due to effects of the Proposed Development alone and in-combination with other plans and projects.

5.7.4.    Farne Islands SPA

European site information and conservation objectives

1600. The Farne Islands SPA are a group of low-lying islands located 2 - 8 km off the coast of Northumberland in northeast England, approximately 50 km from the Proposed Development. The Farne Islands was first classified as an SPA in 1985, with the surrounding marine environment protected by the Northumberland Marine SPA, which was classified in 2017 to protect the foraging areas of breeding seabirds.
1601. There are four Annex I qualifying features and the site qualifies under Article 4.2 by regularly supporting one migratory seabird species and in excess of 20,000 breeding seabirds, including four named component species as identified on the citation but with a further six identified by Natural England in their scoping advice (Table 5.106, volume 3, appendix 6.2 of the Offshore EIA Report). The potential for LSE has been identified in relation to six of these 15 species (Table 5.106), with the effect pathways associated with LSE for each of these detailed in Table 3.1 and set out in the assessment below.
1602. The conservation objectives of this SPA (as determined through Natural England’s Access to Evidence) are to:

Ensure that the integrity of the site is maintained or restored as appropriate, and ensure that the site contributes to achieving the aims of the Wild Birds Directive, by maintaining or restoring:

• The extent and distribution of the habitats of the qualifying features
• The structure and function of the habitats of the qualifying features
• The supporting processes on which the habitats of the qualifying features rely
• The populations of each of the qualifying features
• The distribution of qualifying features within the site
  1603. Further information on this European site, including the SACOs, is presented in appendix 3A.

Table 5.106: Details on the Qualifying Features of the Farne Islands SPA

*Named components of the assemblage only.

**Named components of the assemblage only which are not identified on the citation but are included on the basis of the Natural England scoping advice (volume 3, appendix 6.2 of the Offshore EIA Report).

Assessment for the kittiwake population

1604. The Farne Islands SPA kittiwake population is currently estimated to number 8,804 individuals, based upon the most recently available count data from 2019 (Offshore EIA Report, volume 3, appendix 11.5). The SPA population was estimated to number between approximately 12,000 – 12,500 birds during the early 1990s (SMP 2022) but has since declined, although the decline is not as marked as in many of the kittiwake SPA populations on the east coast of Scotland and numbers remain just above the citation level.

The potential for impacts on the kittiwake population

1605. The Proposed Development and two kilometre buffer around the Proposed Development array area7 do not overlap with the Farne Islands SPA, so that potential impacts on its kittiwake population will only arise as a result of individuals from the colony occurring in the area (or vicinity) of the Proposed Development. Consequently, the main focus of the assessment for this SPA population is concerned with the Conservation Objective of maintaining or restoring the populations of each qualifying feature, because the other Conservation Objectives either apply to the site itself, and not to areas beyond the boundary, or are encompassed by the assessment of this Conservation Objective (as for maintaining or restoring the structure and function of the habitats of the qualifying features, because habitat structure and function would only be considered significant if it caused an adverse effect on the maintenance or restoration of the population of the qualifying features). In terms of the SACOs, this focus is most closely reflected in the attributes concerned with the abundance and diversity of the species assemblage which have the targets of maintaining; (i) the abundance of the breeding seabird assemblage qualifying feature at a level above 163,819 individuals, whilst avoiding deterioration from its current levels; and (ii) the species diversity of the breeding seabird assemblage qualifying feature.
1606. From published information on kittiwake foraging ranges generally (Woodward et al. 2019) and evidence from tracking data (Wakefield et al. 2017), it is apparent that during the breeding period kittiwakes from the Farne Islands SPA may occur within the area of the Proposed Development and of the two km buffer around the Proposed Development array. This is reflected in the findings of the apportioning exercise, which estimates that approximately 5% of the kittiwakes occurring on the Proposed Development array area during the breeding season derive from this SPA colony (Offshore EIA Report, volume 3, appendix 11.5). The breeding period for kittiwake is defined as mid-April to August, following the NatureScot (2020) guidance.
1607. For the reasons described for the St Abb’s Head to Fast Castle SPA kittiwake population, during the non-breeding season there is likely to be the potential for kittiwake from the Farne Islands SPA to pass through offshore wind farms in the North Sea during the autumn and spring passage periods (defined as September to December and January to mid-April, respectively, on the basis of applying the BDMPS defined periods within the context of the overall non-breeding period defined by NatureScot – Furness 2015, NatureScot 2020, Offshore EIA Report, volume 3, appendix 11.5). Given the above, the Proposed Development may have potential effects on the Farne Islands SPA kittiwake population during breeding and non-breeding periods.

Project alone: construction and decommissioning

Disturbance

1608. Direct disturbance to kittiwakes during the construction phase may arise within the Proposed Development array area (and its immediate vicinity) as a result of increased vessel movements and helicopter activity, as well as from other activities directly associated with the installation of the wind turbine foundations and other infrastructure, whilst there will also be increased vessel activity along the Proposed Development export cable corridor due to the cable laying activities. The levels of such activities that could arise are outlined in Table 4.1, with these activities occurring during construction campaigns within a construction period of at most eight years duration.
1609. A total of up to 11,482 vessel round trips may occur over the construction phase, whilst it is estimated that a maximum of 134 vessels could occur within the area of the Proposed Development at any one time (Table 4.1). However, this is within the context of high baseline levels of vessel traffic within this area (e.g. surveys recorded an average of 14 vessels per day within a 10 nm buffer around the Proposed Development over a 14-day period in August 2022, whilst also showing an average of three to four vessels intersecting the Proposed Development array area per day over summer - Offshore EIA Report, volume 2, chapter 13).
1610. When using the marine environment (and not at the breeding colony), kittiwakes are considered to have a relatively low sensitivity to such sources of direct disturbance. Thus, reviews of the sensitivity of different seabird species to disturbance from vessels and helicopter traffic assign kittiwake as ‘2’ on a five-scale ranking system, where 1 indicates hardly any or limited escape/avoidance behaviour and very short flight distance when approached and 5 indicates strong escape/avoidance behaviour and a large response distance (Garthe and Hüppop 2004, Furness et al. 2013).
1611. The total area to be affected by such disturbance over the full eight years of the construction phase also represents a small proportion of the total area of marine habitat available to kittiwakes from the Farne Islands SPA. Thus, the Proposed Development array area encompasses 1,010 km2, whilst the Proposed Development export cable corridor encompasses 168 km2. Together these areas represent less than 1% of the total breeding season foraging area that is potentially available to the SPA kittiwake population, as defined by the generic measure of the species’ mean maximum breeding season foraging range plus 1 SD (i.e.156.1±144.5 km - Woodward et al. 2019) and assuming that this range is represented by a semicircle to the (main) seaward side of the colony. Similarly, the Proposed Development array and export cable corridor represent approximately 3% of the breeding season foraging area if considering the mean maximum foraging range only.
1612. Tracking data (and associated modelling of foraging distributions) for kittiwake appear to suggest that the Proposed Development array area and Proposed Development export cable corridor are beyond waters that are heavily used by birds from the Farne Islands SPA during the breeding season (Wakefield et al. 2017).
1613. During the non-breeding periods, kittiwake distribution is not constrained by the location of the breeding colonies and birds from the SPA population are likely to occur across large expanses of oceanic and maritime waters (Frederiksen et al. 2012, Furness 2015) and the potential for effects of construction-related disturbance is lower than during the breeding season.
1614. In addition, it is important to consider that the construction activities will not occur simultaneously across the entirety of the Proposed Development array area or the Proposed Development export cable corridor but, rather, will be carried out in different areas at different times. Thus, the activities will be concentrated within discrete (often small) parts of these wider areas, and within such areas they will not extend over the full duration of the construction phase, so further reducing the potential to which birds may be subject to disturbance effects. For example, cable laying for the Proposed Development export cable will occur over a total of two years, whilst within the Proposed Development array area it is likely that construction activities would be confined largely to discrete areas at any one time.
1615. The potential for disturbance effects during decommissioning is assumed to be the same (or less) as for construction, noting that the duration of the decommissioning phase will not exceed that of construction, and may be shorter.
1616. Given the low sensitivity of kittiwake to disturbance effects, the relatively small areas that will be subject to activities with the potential to result in disturbance at any given time during the construction period and the fact that these potential effects will be temporary, it is considered that there is no potential for construction or decommissioning related disturbance to lead to an adverse effect on the Farne Islands SPA kittiwake population. This conclusion is consistent with the outcome of the EIA which ‘screened’ out kittiwake as a species for which detailed consideration of the effects of construction disturbance was required (volume 2, chapter 11 of the Offshore EIA Report).

Displacement

1617. As detailed above, kittiwake is considered to have a low sensitivity to disturbance, whilst potential effects of disturbance during the construction and decommissioning phases will only extend across a small part of the wider foraging areas used by the Farne Islands SPA kittiwake population and be limited to, at most, an eight year period during construction (and a likely similar or shorter period during decommissioning). Furthermore, as detailed above, potential effects of disturbance will not occur simultaneously across the entirety of the Proposed Development array area or Proposed Development export cable corridor but, rather, will be carried out in different areas at different times. Thus, at any given time the potential for disturbance effects that could lead to displacement of kittiwakes from this SPA will be limited to relatively small areas, with the potential effects also being of a temporary nature.
1618. Therefore, based upon the above, it is considered that there is relatively little potential for the Farne Islands SPA kittiwake population to be affected by displacement during the construction or decommissioning phases, with any such effects only extending across relatively small areas and tending to be temporary in nature. Consequently, it is considered that there is no potential for construction or decommissioning related displacement to lead to an adverse effect on the Farne Islands SPA kittiwake population. This conclusion is consistent with the outcome of the EIA which ‘screened’ out kittiwake as a species for which detailed consideration of the effects of construction-related displacement was required (volume 2, chapter 11 of the Offshore EIA Report).

Changes to prey availability

1619. Key prey species for kittiwakes include sandeel and sprat (del Hoyo et al., 1996). Indirect effects on kittiwakes may arise as a result of changes in the availability, distribution, or abundance of these species during the construction and decommissioning phases of the Proposed Development. Reduction or disruption to prey availability may cause displacement from foraging grounds or reduced energy intake, affecting survival rates or productivity in the Farne Islands SPA kittiwake population in the short-term.
1620. During construction and decommissioning there are a number of ways in which effects on key prey species of seabirds may occur, which are outlined in the section on Project Alone: Construction and Decommissioning – Changes to Prey Availability for the St Abb’s Head to Fast Castle SPA kittiwake population. The same evidence basis and context applies to the Farne Islands SPA kittiwake population as to the St Abb’s Head to Fast Castle SPA population in relation to the potential for such effects to lead to impacts on the population.
1621. Given this, it is considered that there is relatively little potential for the Farne Islands SPA kittiwake population to be affected by changes to prey availability during the construction and decommissioning phases, with any such effects being largely intermittent across a relatively small spatial extent, with most effects temporary in nature. Consequently, it is considered that there is no potential for construction or decommissioning related changes in prey availability to lead to an adverse effect on the Farne Islands SPA kittiwake population.

Project alone: operation and maintenance

Disturbance

1622. Vessel use and associated activities within the Proposed Development array area and export cable corridor during the operation and maintenance phase may lead to direct disturbance of kittiwakes from Farne Islands SPA. As described in the section on Project Alone: Construction and Decommissioning – Disturbance for the SPA population, kittiwakes are considered to have a relatively low sensitivity to such sources of direct disturbance at sea (Garthe and Hüppop 2004, Furness et al., 2013).
1623. The maximum design scenario is for up to 3,393 vessel round trips per year over the operational lifetime of the project. Vessel types which will be required during the operation and maintenance phase include those used during routine inspections, repairs and replacement of equipment, major component replacement, painting or other coatings, removal of marine growth, replacement of access ladders, and geophysical surveys (Table 4.1).
1624. Based on information presented in the section on Project Alone: Operation and Maintenance – Disturbance for the St Abb’s Head to Fast Castle SPA kittiwake population and in volume 2, chapter 13 of the Offshore EIA Report, baseline levels of vessel traffic in the Offshore Ornithology study area are relatively high. In the context of the baseline levels of vessel traffic across the Offshore Ornithology study area, the increase during the operation and maintenance phase is considered to be relatively small. Vessel movements will be within the Proposed Development array area and export cable corridor and will follow existing shipping routes to/from ports. In addition, Project Codes of Conduct included as a part of the NSVMP (volume 4, appendix 25 of the Offshore EIA Report) will be issued to all project vessel operators to avoid sudden changes in course or speed which will minimise the potential for disturbance. Within the Proposed Development array area, movements and associated maintenance activities will be restricted to individual wind turbines over a period of days to weeks.
1625. The size and noise outputs from vessels during the operation and maintenance phase will be similar to those used in the construction phase. However, the number of vessel return trips per year and their frequency will be much lower for the operation and maintenance phase compared to the construction phase. In addition, activities during the operation and maintenance phase will not occur simultaneously across the entirety of the Proposed Development array area and export cable corridor but intermittently within discrete (often very small) parts of these wider areas.
1626. Given the discrete areas relative to the species’ foraging range that will be subject intermittently to potential disturbance from vessel use and maintenance activities (Woodward et al., 2019), and the fact that these potential effects will be reduced compared to the construction and decommissioning phases, it is considered that there is no potential for disturbance during operation and maintenance to lead to an adverse effect on the Farne Islands SPA kittiwake population.

Displacement/barrier effects

1627. As outlined above, the SNCB matrix approach provides the basis for estimating displacement effects on seabird species in this assessment, with this approach assumed to also incorporate the impact of barrier effects within the estimates that are derived (SNCBs 2022, Offshore EIA Report, volume 3, appendix 11.5). Thus, throughout this section, mortality from displacement is assumed to refer to that which results from both displacement and barrier effects. The approach used to derive predicted levels of mortality is as described in the section on Project Alone: Operation and Maintenance – Displacement/Barrier Effects for the St Abb’s Head to Fast Castle SPA kittiwake population above (and in the Offshore EIA Report, volume 3, appendix 11.5).
1628. On the basis of the advice provided in the Scoping Opinion (volume 3, appendix 6.2 of the Offshore EIA Report), displacement effects on kittiwake are estimated for the breeding and non-breeding periods, with the latter separated into autumn and spring passage periods (Offshore EIA Report, volume 3, appendix 11.5). The displacement and associated mortality rates advised in the Scoping Opinion (subsequently termed the Scoping Approach) for kittiwake are:

• Breeding period: 30% displacement with lower and upper mortality rates of 1% and 3%.
• Non-breeding periods: 30% displacement with lower and upper mortality rates of 1% and 3%.
  1629. However, the approach to estimating kittiwake displacement effects advocated by the Scoping Opinion was considered overly precautionary in relation to the upper mortality rate used and the incorporation of mortality effects in the non-breeding periods, as detailed in volume 3, appendix 11.4, annex G of the Offshore EIA Report. In particular, it represented a marked change from the assumptions applied in assessments for other recent Scottish offshore wind farms (Marine Scotland 2017a,b,c) with no clear evidence apparently being available to justify such a change. Thus, based on a consideration of the available evidence for kittiwake displacement, the extent of the species’ ranging behaviour (particularly in the non-breeding periods), previous precedent and a need to incorporate precaution within the assessment, an alternative Developer Approach to estimating displacement effects was determined (volume 3, appendix 11.4, annex G of the Offshore EIA Report). The rates adopted by the Developer Approach are:
• Breeding period: 30% displacement with a mortality rate of 2%.
• Non-breeding periods: No measurable effects of displacement on mortality.
  1630. Estimates of kittiwake mortality were produced using the SNCB matrix on the basis of both the Scoping Approach and the Developer Approach (Offshore EIA Report, volume 3, appendix 11.5), with these estimates then apportioned to the Farne Islands SPA kittiwake population during the breeding and non-breeding periods according to the MS Apportioning Tool (Butler et al. 2020) and the BDMPS approach (Furness 2015), respectively (Offshore EIA Report, volume 3, appendix 11.5; Table 5.107). The resulting mortality estimates for the breeding period were apportioned to age classes on the basis of the plumage characteristics of kittiwakes recorded during the breeding period in the baseline surveys (Offshore EIA Report, volume 3, appendix 11.1), whilst for the non-breeding periods age classes were apportioned according to the stable age distributions of the population model used in Furness (2015). Based on advice provided by NatureScot and Marine Scotland Science following Roadmap Meeting 4 (G. Holland, email 26/01/2022), it was also assumed that 10% of the breeding adults in the SPA population miss breeding in any given year (i.e. sabbatical birds) so that the number of estimated adult deaths during the breeding season was adjusted accordingly.

Table 5.107: The Mean Peak Abundance Estimates of Kittiwake in the Proposed Development Array Area and 2 km Buffer for each Seasonal Period, Together with the Proportion of Birds Estimated to Belong to the Breeding Adult Age Class and to be from the Farne Islands SPA Population in Each Period. The Proportion of Adults Assumed to be Sabbaticals During the Breeding Season is also Presented

1631. Based upon the estimates and assumptions detailed above, the potential annual mortality amongst the SPA kittiwake population as a result of displacement is estimated as three adult and 0.3 immature birds based on the lower mortality rates for the Scoping Approach (i.e. Scoping Approach A) and as nine adult and one immature birds based upon the higher mortality rates for the Scoping Approach (i.e. Scoping Approach B) (Table 5.108). As expected on the basis that kittiwakes from this breeding colony SPA may use the waters within the vicinity of the Proposed Development array area during the breeding season (and as reflected by the seasonally-specific apportioning rates), the displacement effects predicted by the Scoping Approach are largely attributable to the breeding season (with the potential breeding season mortality accounting for almost 80% of the overall annual mortality – Table 5.108).
1632. The annual mortality from displacement as determined using the Developer Approach is predicted to be approximately five adult and 0.2 immature birds, so lies midway between the mortality predictions from the Scoping Approach and is entirely attributable to breeding season effects (on the basis that displacement effects on kittiwake during the non-breeding periods are not considered to result in detectable impacts on the population – volume3, appendix 11.4, annex G of the Offshore EIA Report).

Table 5.108: Estimated Potential Annual Mortality of Farne Islands SPA Kittiwakes as a Result of Displacement from the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach

1633. The additional annual mortality of adult kittiwakes from the Farne Islands SPA population predicted due to displacement from the Proposed Development array represents 0.06% of the current adult breeding population at this colony (i.e. 8,804 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach, and between approximately 0.03 – 0.10% of this population as determined by the lower and upper estimates from the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.145 – see Table 2.13 in volume 3, appendix 11.6 of the Offshore EIA Report), the estimates of adult mortality equate to an increase of 0.4% for the Developer Approach and of 0.24 – 0.70% for the lower and upper estimates from the Scoping Approach.
1634. The potential levels of impact on the Farne Islands SPA kittiwake population resulting from the mortality predicted from displacement and barrier effects associated with the Proposed Development array during the operation and maintenance phase are considered in more detail below in the Project Alone: Population-Level Impacts section. This presents the outputs from PVAs of the combined effects of predicted displacement and collision mortality on the SPA population.

Collision risk

1635. Predictions of the number of kittiwakes at risk from collisions due to the Proposed Development were calculated using the deterministic version of the SOSS offshore collision risk model (Band 2012, Offshore EIA Report, volume 3, appendix 11.3). Following the Scoping Opinion (volume 3, appendix 6.2 of the Offshore EIA Report), the assessment is based on option 2 of the CRM, which uses the generic flight height data from Johnston et al. (2014a,b) and assumes a uniform distribution of flight heights across the rotor swept zone (as opposed to using the modelled flight height distribution) (Band 2012). An avoidance rate of 98.9% was applied to these CRM outputs, as recommended for kittiwake (SNCBs 2014) and as advised by the Scoping Opinion.
1636. As detailed for the St Abb’s Head to Fast Castle SPA kittiwake population, guidance on the use of the CRM suggests that model predictions should be based upon the mean monthly densities of flying birds estimated within the array area (Band 2012)8 and, to the best of the Applicant’s knowledge, this approach has been applied in all recent UK offshore wind farm assessments. Despite this, the Scoping Opinion advised that the CRMs for the Proposed Development should use the maximum monthly densities of flying birds within the array area. Further details on this are provided above in the Project Alone: Operation and Maintenance - Collision Risk section for the St Abb’s Head to Fast Castle SPA kittiwakes (and in volume 3, appendix 11.3 of the Offshore EIA Report) but, as a result of this overly precautionary approach (which does not follow previous precedent), the CRMs for Farne Islands SPA kittiwakes were undertaken following:

• The Scoping Approach of using the maximum monthly densities, and
• The Developer Approach of using the mean monthly densities.
  1637. As for the St Abb’s Head to Fast Castle SPA kittiwake population, collision estimates were also calculated:
• Using option 2 of the deterministic version of the CRM but with site-specific flight height data from boat-based surveys of the Proposed Development array area10 (as opposed to the generic flight height data of Johnston et al. 2014a,b).
• Using options 2 and 3 of the stochastic version of the CRM (McGregor et al. 2018) with avoidance rates as derived from the bird collision-avoidance study undertaken at the Thanet offshore wind farm (Bowgen and Cook 2018), noting that option 3 of the CRM uses the modelled flight height distributions from Johnston et al. (2014a,b).
  1638. These additional collision estimates are not used as the basis of the assessments on the SPA kittiwake populations but, instead, are used in a comparative way to illustrate the extent to which some estimates may vary according to certain of the key assumptions on which they are based. Details of these additional CRMs are provided in annex B and annex C of the Offshore EIA Report, volume 3, appendix 11.3.
  1639. As for the predicted displacement effects, kittiwake collision estimates are calculated for the breeding and non-breeding periods, with the latter separated into autumn and spring passage periods (Offshore EIA Report, volume 3, appendix 11.5). Estimates were apportioned to the Farne Islands SPA population during the breeding and non-breeding periods according to the MS Apportioning Tool (Butler et al. 2020) and the BDMPS approach (Furness 2015), respectively (volume 3, appendix 11.5, Table 5.107 of the Offshore EIA Report). The age class proportions and assumptions on sabbatical rates are also as detailed above in relation to displacement effects (Table 5.107).
  1640. Based upon option 2 of the deterministic CRM with a 98.9% avoidance rate applied, and in conjunction with the estimates and assumptions detailed above, the annual collision mortality of kittiwakes from the Farne Islands SPA is predicted to be approximately 26 adults and two immatures as determined by the Scoping Approach, and approximately 18 adults and one immature as determined by the Developer Approach (Table 5.109). As for displacement, the vast majority of this mortality (i.e. over 90%) is predicted to occur during the breeding season.

Table 5.109: Predicted Collision Effects from the Proposed Development on the Farne Islands SPA Kittiwake Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenarioand are Based on Option 2 of the Deterministic CRM Using a 98.9% Avoidance Rate (see text)

1641. The additional annual mortality of adult kittiwakes from the Farne Islands SPA population predicted due to collisions with wind turbines in the Proposed Development array represents approximately 0.21% of the number of adults currently estimated to breed at this colony (i.e. 8,804 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach and approximately 0.30% as determined by the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.145 – see Table 2.13 in volume 3, appendix 11.6 of the Offshore EIA Report), the predicted adult collision mortality equates to increases of 1.4% and 2.1% for the Developer and Scoping Approaches, respectively.
1642. As outlined in the Project Alone: Operation and Maintenance - Collision Risk section for the St Abb’s Head to Fast Castle SPA kittiwake population, using the collision estimates derived from the site-specific flight height data or from the stochastic CRM with avoidance rates as calculated for the bird collision-avoidance study (Bowgen and Cook 2018) would result in predicted collision mortalities on the Farne Islands SPA kittiwake population that are at least 50% lower than those presented in Table 5.109 above (and on which the assessment is based).
1643. More detailed consideration of the potential population-level impacts associated with the predicted collision mortalities in Table 5.109 is undertaken below in the Project Alone: Population-Level Impacts section, which presents the outputs from PVAs of the combined effects of predicted displacement and collision mortality on the SPA population.

Changes to prey availability

1644. Potential impacts on key prey species for kittiwakes breeding at the Farne Islands SPA during the operation and maintenance phase have been assessed in volume 2, chapter 9 of the Offshore EIA Report using the appropriate maximum design scenarios for these receptors. Reduction or disruption to prey availability through temporary and long-term subtidal habitat loss/disturbance, increased SSC and deposition, EMF from subsea electrical cabling, and colonisation of subsea structures, could affect kittiwake survival and productivity in the Farne Islands SPA kittiwake population.
1645. The same evidence basis and context in relation to this effect pathway for the operation and maintenance phase applies to the Farne Islands SPA kittiwake population as to the St Abb’s Head to Fast Castle SPA kittiwake population. This is detailed in the section on Project Alone: Operation and Maintenance – Changes to Prey Availability for the St Abb’s Head to Fast Castle SPA population.
1646. Given this, it is considered that there is relatively little potential for the Farne Islands SPA kittiwake population to be affected by changes to prey availability during the operation and maintenance phase, with any such effects being largely intermittent across a relatively small spatial extent. Consequently, it is considered that there is no potential for operational or maintenance related changes in prey availability to lead to an adverse effect on the Farne Islands SPA kittiwake population.

Project alone: population-level impacts

1647. As determined above, the effects from the Proposed Development alone which could lead to an adverse effect on the Farne Islands SPA kittiwake population are displacement (inclusive of barrier effects) and collision mortality during the operation and maintenance phase. For other effect pathways, there is considered to be no potential for an adverse effect on this population as a result of the Proposed Development alone, with any such effects likely to be small and of little, or no, consequence in terms of impacts at the population level.
1648. Given this, PVA was undertaken on the mortality to the adult and immature age classes predicted due to the combined displacement and collision effects associated with the Proposed Development, as determined by both the Scoping and Developer Approaches (see Tables 5.108 and 5.109 above). The population model for the SPA population was a stochastic, density independent, matrix model, based upon the demographic parameters specified in Table 2.13 of volume 3, appendix 11.6 of the Offshore EIA Report. The starting population size was the 2019 count for the SPA, with the projected population trends considered over a 35 year timescale (Offshore EIA Report, volume 3, appendix 11.5). The approach and methods to undertaking the PVA are as described in the section on Project Alone: Population-Level Impacts for St Abb’s Head to Fast Castle SPA kittiwake population above (with further details provided in volume 3, appendix 11.6 of the Offshore EIA Report).
1649. Outputs from the PVA are summarised according to the median predicted population-sizes at the end of the projection period, and the three metrics which the Scoping Opinion (volume 3, appendix 6.2 of the Offshore EIA Report) advised should be used for the interpretation of outputs and which have been shown to have relatively low sensitivity to factors such as varying population status and the mis-specification of the demographic rates underpinning the population model (Cook and Robinson 2015, Jitlal et al., 2017). These metrics are:

• The CPS – the median of the ratio of the end-point size of the impacted to un-impacted (or baseline) population, expressed as a proportion;
• The CPGR - the median of the ratio of the annual growth rate of the impacted to un-impacted population, expressed as a proportion; and
• The centile of the un-impacted population that matches the median (i.e. 50th centile) of the impacted population (based upon the distribution of the end-point population-sizes generated by the multiple replications of the model runs, the value should always be less than 50 because the median for the impacted population is not expected to exceed that for the un-impacted population).

Table 5.110: Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Kittiwake Population Under Different Impact Scenarios for the Proposed Development Alone

1650. The PVA predicted a continuing population decline for the Farne Islands SPA kittiwake population, irrespective of the effects from the Proposed Development. Thus, under baseline conditions (i.e. no wind farm effects), the population is predicted to decline by 45% after 35 years from the current estimate of 8,804 adult birds (Table 5.110). Given that the PVAs are based on density independent models, which assume all mortality from the wind farm effects is additive and that there are no compensatory mechanisms operating within the population, the predicted declines are inevitably greater for those scenarios incorporating the effects from the Proposed Development (with the predicted decline in population size being 50% as determined by Scoping Approach B, for which the predicted effects are greatest).
1651. Considering the PVA metrics, the CPS values indicate that the SPA population size would be reduced by approximately 7% and 9 – 11%, relative to the predicted population size under baseline conditions, after 35 years for the Developer Approach and Scoping Approach, respectively (Table 5.110). Reductions in the annual population growth rate (relative to that predicted under baseline conditions) are estimated to be approximately 0.2% on the basis of the Developer Approach and 0.3% on the basis of the Scoping Approach (Table 5.110). On the basis of the Developer Approach, the centile value is estimated to be 43 after 35 years, whilst for the Scoping Approach the equivalent values are 39.3 – 41.1 (Table 5.110). Thus, overall, the centile metric indicates considerable overlap in the distribution of the predicted impacted and un-impacted population sizes, suggesting a high likelihood of the impacted population being of similar size to the un-impacted population after 35 years, irrespective of whether the effects are estimated using the Developer or Scoping Approaches.
1652. The PVA outputs described above, and detailed in Table 5.110, need to be considered within the context of the fact that the SPA population is predicted to decline irrespective of the wind farm effects and that such a trend is broadly consistent with the documented long-term trend for this population (see above). As described in the Project Alone: Population-Level Impacts section for the St Abb’s Head to Fast Castle SPA kittiwake population, the available evidence suggests that the long-term decline of kittiwake populations in the North Sea (including the Farne Islands SPA) is associated with fisheries management and climate change (Frederiksen et al. 2004). Therefore, without appropriate management to mitigate these effects, it is likely that the Farne Islands SPA population will continue to decline and that the predicted effects from the Proposed Development may be of limited importance relative to these broader-scale effects. Furthermore, it is also relevant to consider the high levels of precaution incorporated within the assessment, particularly as determined by the Scoping Approach (with this also detailed in the Project Alone: Population-Level Impacts section for the St Abb’s Head to Fast Castle SPA kittiwake population).

Project alone: conclusion

1653. Overall, it is considered that the predicted levels of impact from the Proposed Development alone on the Farne Islands SPA kittiwake population are of a relatively small scale. For both the Developer and Scoping Approaches it is also the case that the centile metric indicates a high likelihood of the impacted population being of similar size to the un-impacted population after 35 years. Given this is within the context of a population which (consistent with the documented long-term trend) is predicted to decline irrespective of the effects from the Proposed Development, and for which the assessment incorporates high levels of precaution (particularly as determined by the Scoping Approach), it is concluded that the effects from the Proposed Development alone would not result in an adverse effect on this SPA population.

Effects in-combination

Effects of relevance to the in-combination assessment

1654. As detailed above, any effects from the Proposed Development alone on the Farne Islands SPA kittiwake population during construction and decommissioning and resulting from disturbance and changes to prey availability during operation and maintenance will be small and highly localised. As such, there is considered to be no potential for these effect pathways to add to impacts at the population-level that might result from other effects pathways associated with the Proposed Development or from the effects due to other plans and projects.
1655. Therefore, the potential for effects of the Proposed Development to act on the Farne Islands SPA kittiwake population in-combination with other plans and projects is limited to the displacement (inclusive of barrier effects) and collision risk effect pathways during operation and maintenance. The following sections consider these potential effects for the Proposed Development in-combination with the offshore wind farms in the UK North Sea.