Project alone: population-level impacts
  1. As determined above, the effects from the Proposed Development alone which could lead to an adverse effect on the Farne Islands SPA razorbill population are limited to displacement (inclusive of barrier effects) 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.
  2. Given this, PVA was undertaken on the mortality to the adult and immature age classes predicted due to the displacement effects associated with the Proposed Development, as determined by both the Scoping and Developer Approaches (see Tables 5.122 above). The population model for the SPA population was a stochastic, density independent, matrix model, based upon the demographic parameters specified in Table 2.19 of volume 3, appendix 11.6 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 (volume 3, appendix 11.5 of the Offshore EIA Report). The approach and methods to undertaking the PVA are as described in the section on Project Alone: Population-Level Impacts for the St Abb’s to Fast Castle SPA kittiwake population above (with further details provided in volume 3, appendix 11.6 of the Offshore EIA Report).
  3. 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 5.123:
Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Razorbill Population Under Different Impact Scenarios for the Proposed Development Alone

Table 5.123: Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Razorbill Population Under Different Impact Scenarios for the Proposed Development Alone

 

  1. The PVA predicted that the Farne Islands SPA razorbill population would increase over the 35 year projection period irrespective of the effects from the Proposed Development. Thus, the population is predicted to be almost seven times larger than the current estimate of 572 adult birds under all scenarios, including the baseline which assumes no wind farm effects (Table 5.123). Although the predicted increases in population size are inevitably greatest for the baseline scenario (because 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 differences with the impact scenarios are small. The predicted levels of increase are unlikely to occur in reality (and are, in part, a consequence of the absence of any compensatory density dependence within the models – as discussed in the section on Project Alone: Population-level impacts for the St Abb’s Head to Fast Castle SPA kittiwake population), whilst it is also notable that the predicted increase differs from the documented relative stability (albeit with between-year fluctuations) in the size of this SPA population over the last 15 years or so (see above).
  2. The predicted population-level impacts are small, irrespective of whether these are determined using the Developer or Scoping Approaches. Thus, for the higher mortality rates for the Scoping Approach (B), the CPS value indicates that the displacement effects from the Proposed Development alone would result in a reduction of 3% in the size of the SPA population after 35 years, relative to that in the absence of any wind farm effects (Table 5.123). The associated reduction in annual population growth rate (relative to that predicted under baseline conditions) is estimated to be 0.1%, whilst the centile value of 45.8 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. As would be expected, the metrics as determined from either the lower mortality rates of the Scoping Approach or the Developer Approach suggest even smaller levels of impact (Table 5.123).
  3. For the same reasons as described in the section on Project-Alone: Population-Level Impacts for the St Abb’s Head to Fast Castle SPA razorbill population, the assessment of the Farne Islands SPA razorbill population incorporates high levels of precaution, which extend beyond the differences between the Developer and Scoping Approaches that are outlined above (and detailed in the Offshore EIA Report, volume 3, appendix 11.4). Notably, the concerns over the extent to which the seasonal mean peak abundances (which provide the basis for the displacement mortality estimates) are likely to be representative of the overall usage of the Proposed Development array and two kilometre buffer by razorbill are equally relevant to the Farne Islands SPA population as to the St Abb’s Head to Fast Castle SPA population. The evidence available from tracking data suggests that levels of usage of the Proposed Development array area and two kilometre buffer during the breeding season by razorbills from the Farne Islands SPA are likely to be low (Wakefield et al. 2017).
Project alone: conclusion
  1. It is considered that the predicted levels of impact from the Proposed Development alone on the Farne Islands SPA razorbill population are of a small scale, as determined by both the Developer and Scoping Approaches. 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. These levels of impact are within the context of an assessment which incorporates high levels of precaution (particularly as determined by the Scoping Approach). Given this, it is concluded that the effects from the Proposed Development alone (as determined by either the Developer or Scoping Approaches) would not result in an adverse effect on this spa population.
Effects in-combination
Effects of relevance to the in-combination assessment
  1. As detailed above, any effects from the Proposed Development alone on the Farne Islands SPA razorbill 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.
  2. Therefore, the potential for effects of the Proposed Development to act on the Farne Islands SPA razorbill population in-combination with other plans and projects is limited to the displacement (inclusive of barrier effects) effect pathway during operation and maintenance. The following sections consider these potential effects for the Proposed Development in-combination with the other UK North Sea wind farms.
Displacement/barrier effects – operation and maintenance
  1. As described in Offshore EIA Report, annex E of volume 3, appendix 11.6, estimates of breeding season displacement mortality which had been attributed to the Farne Islands 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.
  2. 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 Offshore EIA Report annex D of volume 3, appendix 11.6 for more details). The cumulative numbers for each of the non-breeding periods were apportioned to the Farne Islands 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 5.122).

 

Table 5.124:
Estimated Annual Mortality of Farne Islands 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 the other UK North Sea Wind Farms

Table 5.124: Estimated Annual Mortality of Farne Islands 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 the other UK North Sea Wind Farms

 

  1. The potential mortality from the displacement effects associated with the other UK North Sea wind farms is limited to the passage periods, with none of these other wind farms identified as contributing to breeding season effects on this SPA population (see annex E of Offshore EIA Report, volume 3, appendix 11.6). Overall, the effects from the Proposed Development in-combination with the other UK North Sea wind farms represented an approximate threefold increase in the potential mortality predicted for the Proposed Development alone (for both Developer and Scoping Approaches). The potential mortality from the in-combination scenario was concentrated in the non-breeding periods for both the Developer and Scoping Approaches (Table 5.124).
  2. The additional annual mortality of adult razorbills from the Farne Islands SPA population predicted due to displacement from the Proposed Development in-combination with the other UK North Sea wind farms represents 0.09% of the current adult breeding population at this colony (i.e. 572 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach, and between approximately 0.10 – 0.31% 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 1.0% for the Developer Approach and of 1.2 – 3.5% for the lower and upper estimates from the Scoping Approach.
  3. The potential levels of impact on the Farne Islands SPA razorbill population resulting from the mortality predicted from displacement and barrier effects associated with the Proposed Development in-combination with the other UK North Sea wind farms 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
  1. 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 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 5.124 above).
  2. 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 5.125:
Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Razorbill Population Under Different Impact Scenarios for the Proposed Development in-Combination with the other UK North Sea Wind Farms

Table 5.125: Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Razorbill Population Under Different Impact Scenarios for the Proposed Development in-Combination with the other UK North Sea Wind Farms

 

  1. 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 the other UK North Sea wind farms suggest greater population-level impacts than as predicted for the Proposed Development alone (compare Table 5.125 with Table 5.123). However, overall, the predicted levels of impact remain relatively small.
  2. The CPS value for the Developer Approach indicates that the in-combination displacement effects would result in a reduction of less than 3% in the size of the SPA population after 35 years, relative to that in the absence of any wind farm effects, whilst for the Scoping Approach the CPS values indicate reductions of 4 – 10% after 35 years, relative to that in the absence of any wind farm effects (Table 5.125). The associated reduction in annual population growth rate (relative to that predicted under baseline conditions) is 0.1% for the Developer Approach and 0.1 – 0.3% for the Scoping Approach. The centile values of 37.1 (for the higher mortality rates of the Scoping Approach) to 46.4 (for the Developer Approach) indicate considerable overlap in the distributions of the predicted impacted and un-impacted population sizes and, hence, at least a reasonably high likelihood of the impacted population being of a similar size to the un-impacted population after 35 years (Table 5.125).
In-combination: conclusion
  1. It is considered that the predicted levels of impact from the Proposed Development in-combination with the other UK North Sea wind farms on the Farne Islands SPA razorbill population are of a relatively small scale, as determined by both the Developer and Scoping Approaches. For both the Developer and Scoping Approaches it is also the case that the centile metric indicates at least a reasonably high likelihood of the impacted population being of similar size to the un-impacted population after 35 years. Furthermore, in relation to the Scoping Approach the predicted levels of impact should be considered within the context of the overly precautionary displacement and mortality rates used (volume 3, appendix 11.4, annex G of the Offshore EIA Report).
  2. Given this, it is concluded that the effects from the Proposed Development in-combination with the other UK North Sea wind farms would not result in an adverse effect on this SPA population. This conclusion applies to both the Scoping and Developer Approaches.

 Assessment for the puffin population

  1. The Farne Islands SPA puffin population is currently estimated to number 87,504 individuals, based upon the most recently available count data from 2019 (Offshore EIA Report, volume 3, appendix 11.5). This is above the citation level (Table 5.106) and represents a substantial increase from the earliest count available for the SPA on the SMP database, which estimated 52,658 individuals in 1989 (SMP 2022). Since 1989, the available count data indicate that numbers increased to a peak in the early 2000s (with 111,348 individuals in 2003) but have since varied from 73,670 (in 2008) to 87,912 (in 2018).
The potential for impacts on the puffin population
  1. 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 puffin population will only occur 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.
  2. From published information on puffin foraging ranges (Woodward et al. 2019), it is likely that during the breeding period puffins from the Farne Islands SPA occur within the area of the Proposed Development and of the two km buffer around the Proposed Development array area. This is supported by the findings of the apportioning exercise, which estimates that 38% of the puffins 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 puffin is defined as April to mid-August, following the NatureScot (2020) guidance.
  3. After the breeding season puffin migrate rapidly from their UK breeding areas, leaving the seas immediately adjacent to their colonies by late August and dispersing widely across north-west European seas and the Atlantic (Wernham et al. 2002, Harris and Wanless 2011, Stone et al. 1995, Jessopp et al. 2013). Consequently (and as advised in the NatureScot scoping advice - volume 3, appendix 6.2 of the Offshore EIA Report), no assessment of impacts during the non-breeding period is undertaken for puffin.
Project alone: construction and decommissioning
Disturbance
  1. Direct disturbance to puffins 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.
  2. 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).
  3. When using the marine environment (and not at the breeding colony), puffins 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 puffin 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).
  4. 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 puffins 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 approximately 1% of the total breeding season foraging area that is potentially available to the SPA puffin population, as defined by the generic measure of the species’ mean maximum breeding season foraging range plus 1 SD (i.e. 137.1±128.3 km - Woodward et al. 2019) and assuming that this range is represented by a semicircle to the seaward side of the colony. Similarly, the Proposed Development array and export cable corridor represent approximately 4% of the breeding season foraging area if considering the mean maximum foraging range only.
  5. In addition to the above, 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.
  6. 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.
  7. Given the relatively low sensitivity of puffin 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 puffin population.
Displacement
  1. As detailed above, puffin is considered to have a relatively low sensitivity to disturbance, whilst potential effects of disturbance during the construction and decommissioning phases will (at most) only extend across a small part of the wider foraging areas used by the Farne Islands SPA puffin 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 puffins from this SPA will be limited to relatively small areas, with the potential effects also being of a temporary nature.
  2. Based upon the above, it is considered that there is relatively little potential for the Farne Islands SPA puffin 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 puffin population.
Changes to prey availability
  1. Sandeels are key prey for puffins, with a range of other species taken including clupeids and gadids (del Hoyo et al., 1996). Indirect effects on puffins 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 puffin population in the short-term.
  2. 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 evidence base and context for assessing the potential for such effects to have impacts on the Farne Islands SPA puffin population are as for the Forth Islands SPA puffin population (with the exception that tracking data are not available to inform the foraging ranges used by the Farne Islands birds). These details are presented above in the equivalent section for the Forth Islands SPA puffin population.
  3. Given this, it is considered that there is relatively little potential for the Farne Islands SPA puffin 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 puffin population.
Project alone: operation and maintenance
Disturbance
  1. 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 puffins from Farne Islands SPA. As described in the section on Project Alone: Construction and Decommissioning – Disturbance for the SPA population, puffins are considered to have a low sensitivity to such sources of direct disturbance at sea (Garthe and Hüppop 2004, Furness et al., 2013).
  2. 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).
  3. 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 the Offshore EIA Report, volume 2, chapter 13, 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 (Offshore EIA Report, volume 4, appendix 25) 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.
  4. 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.
  5. 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 puffin population.
Displacement/barrier effects
  1. As outlined above, displacement effects on the Farne Islands SPA puffin population are estimated using the SNCB matrix approach, as applied to the Proposed Development array and two kilometre buffer (SNCBs 2022, Offshore EIA Report, volume 3, appendix 11.4). 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 11.4).
  2. On the basis of the advice provided in the Scoping Opinion (volume 3, appendix 6.2 of the Offshore EIA Report), displacement effects on puffin are estimated for the breeding period only (see above). The displacement and associated mortality rates advised in the Scoping Opinion (subsequently termed the Scoping Approach) for puffin are:
  • Breeding period: 60% displacement with lower and upper mortality rates of 3% and 5%.
    1. As with other species for which displacement effects are assessed (see above), the approach to estimating puffin displacement effects advocated by the Scoping Opinion was considered overly precautionary in relation to both the displacement and mortality rates that were proposed, with these rates being higher than is considered to be justified on the basis of the available evidence (even when allowing for the incorporation of precaution in the assessment - volume 3, appendix 11.4, annex G of the Offshore EIA Report). Furthermore, the mortality rates advocated by the Scoping Opinion 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.
    2. Based upon a consideration of the available evidence for puffin displacement, the potential consequent mortality, 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: 50% displacement with a mortality rate of 1%.
    1. Estimates of puffin 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 11.4), with these estimates then apportioned to the Farne Islands SPA puffin population during the breeding season according to the NatureScot (2018) approach (Offshore EIA Report, volume 3, appendix 11.5, Table 5.126). The resulting mortality estimates for the breeding season were apportioned to age classes on the basis of the asymptotic age distribution of the population model used for the Farne Islands SPA puffin PVAs in this assessment (Offshore EIA Report, volume 3, appendix 11.6). 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 7% 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 5.126:
The Mean Peak Abundance Estimates of Puffin in the Proposed Development Array Area and 2 km Buffer During the Breeding Season, Together with the Proportion of Birds Estimated to Belong to the Breeding Adult Age Class and to be from the Farne Islands SPA Population

Table 5.126: The Mean Peak Abundance Estimates of Puffin in the Proposed Development Array Area and 2 km Buffer During the Breeding Season, Together with the Proportion of Birds Estimated to Belong to the Breeding Adult Age Class and to be from the Farne Islands SPA Population

 

  1. Based upon the estimates and assumptions detailed above, the potential annual mortality amongst the SPA puffin population as a result of displacement is estimated as 13 adult and 17 immature birds based on the lower mortality rates for the Scoping Approach (i.e. Scoping Approach A) and as 21 adult and 29 immature birds based upon the higher mortality rates for the Scoping Approach (i.e. Scoping Approach B) (Table 5.127). For the Developer Approach, the predicted annual mortality is four adult and five immature birds, equating to approximately 28% and 17% of the mortality predicted for the lower and upper range of the Scoping Approach, respectively (Table 5.127).

 

Table 5.127:
Estimated Potential Annual Mortality of Farne Islands SPA Puffins as a Result of Displacement from the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach

Table 5.127: Estimated Potential Annual Mortality of Farne Islands SPA Puffins as a Result of Displacement from the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach

 

  1. The additional annual mortality of adult puffin from the Farne Islands SPA population predicted due to displacement from the Proposed Development array represents less than 0.01% of the current adult breeding population at this colony (i.e. 87,504 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach, and between approximately 0.01 – 0.02% 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 0.099 – see Table 2.17 in volume 3, appendix 11.6 of the Offshore EIA Report), the estimates of adult mortality equate to an increase of less than 0.1% for the Developer Approach and of 0.1 – 0.2% for the lower and upper estimates from the Scoping Approach.
  2. The potential levels of impact on the Farne Islands SPA puffin 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 potential effects of predicted displacement mortality on the SPA population.
Changes to prey availability
  1. Potential impacts on key prey species for puffins breeding at 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, reductions in water clarity, EMF from subsea electrical cabling, and colonisation of subsea structures, could affect puffin survival and productivity in the Farne Islands SPA population.
  2. The same evidence basis and context in relation to this effect pathway for the operation and maintenance phase applies to the Farne Islands SPA puffin population as to the Forth Islands SPA puffin population. This is detailed in the section on Project Alone: Operation and Maintenance – Changes to Prey Availability for the Forth Islands SPA population.
  3. Given this, it is considered that there is relatively little potential for the Farne Islands SPA puffin 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 puffin population.
Project alone: population-level impacts
  1. As determined above, the effects from the Proposed Development alone which could lead to an adverse effect on the Farne Islands SPA puffin population are limited to displacement (inclusive of barrier effects) 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.
  2. Given this, PVA was undertaken on the mortality to the adult and immature age classes predicted due to the displacement effects associated with the Proposed Development, as determined by both the Scoping and Developer Approaches (see Tables 5.127 above). The population model for the SPA population was a stochastic, density independent, matrix model, based upon the demographic parameters specified in Table 2.17 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 (volume 3, appendix 11.5 of the Offshore EIA Report). The approach and methods to undertaking the PVA are as described in the section on Project Alone: Population-Level Impacts for the St Abb’s to Fast Castle SPA kittiwake population above (with further details provided in the Offshore EIA Report, volume 3, appendix 11.6).
  3. 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 5.128:
Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Puffin Population Under Different Impact Scenarios for the Proposed Development Alone

Table 5.128: Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Puffin Population Under Different Impact Scenarios for the Proposed Development Alone

 

  1. The PVA predicted that the Farne Islands SPA puffin population would increase over the 35 year projection period irrespective of the effects from the Proposed Development. Thus, the population is predicted to be more than five times larger than the current estimate of 87,504 adult birds under baseline conditions (i.e. no wind farm effects) and under each of the impact scenarios (Table 5.128). 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 increases are inevitably greatest for the baseline scenario and least for the scenario involving highest annual mortality (i.e. Scoping Approach B). However, the differences between the scenarios in terms of the predicted increases and eventual 35 year population sizes are small. The predicted levels of increase are unlikely to occur in reality (and are, in part, a consequence of the absence of any compensatory density dependence within the models – as discussed in the section on Project Alone: Population-level impacts for the St Abb’s Head to Fast Castle SPA kittiwake population), and whilst the prediction for an increasing trend is broadly consistent with the overall long-term trend for this SPA population it does not reflect the more recent (relative) stability in numbers (see above).
  2. The predicted population-level impacts are small, irrespective of whether these are determined using the Developer or Scoping Approaches. Thus, for the upper range of the Scoping Approach the CPS value indicates that the predicted mortality associated with the Proposed Development alone would result in a reduction of 1% in the size of the SPA population after 35 years, relative to that in the absence of any wind farm effects (Table 5.128). The associated reductions in annual population growth rate (relative to that predicted under baseline conditions) are not detectable (at least when the CPGR value is expressed to three decimal places) and the centile values are all close to, or above, 49, indicating 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 (Table 5.128).
Project alone: conclusion
  1. For both the Developer and Scoping Approaches, the potential effects from the Proposed Development alone on the Farne Islands SPA puffin population are predicted to be small, with the resultant population-level impacts also predicted to be small. In addition, the PVA metrics indicate a high chance of the population being of a similar size to that which would occur in the absence of the Proposed Development after 35 years. Given this, it is concluded that the effects from the Proposed Development alone would not result in an adverse effect on this population (with this conclusion being irrespective of whether these effects are determined by the Scoping or Developer Approach).
Effects in-combination
Effects of relevance to the in-combination assessment
  1. As detailed above, any effects from the Proposed Development alone on the Farne Islands SPA puffin 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.
  2. Therefore, the potential for effects of the Proposed Development to act on the Farne Islands SPA puffin population in-combination with other plans and projects is limited to the displacement (inclusive of barrier effects) effect pathway during operation and maintenance. The following sections consider these potential effects for the Proposed Development in-combination with the other UK North Sea wind farms.
Displacement/barrier effects – operation and maintenance
  1. As described in Offshore EIA Report annex E of volume 3, appendix 11.6, estimates of breeding season displacement mortality which had been attributed to the Farne Islands SPA puffin 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.

 

Table 5.129:
Estimated Annual Mortality of Farne Islands SPA Puffins 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 the other UK North Sea Wind Farms

Table 5.129: Estimated Annual Mortality of Farne Islands SPA Puffins 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 the other UK North Sea Wind Farms

 

  1. Incorporating the potential mortality predicted from the displacement effects associated with the other UK North Sea wind farms leads to increases of approximately 35% in the predicted displacement mortality compared to the Proposed Development alone for each of the Developer and Scoping Approaches (Tables 5.127 and 5.129).
  2. The resultant additional annual mortality of adult puffins from the Farne Islands SPA population predicted due to the in-combination displacement effects less than 0.01% of the current adult breeding population at this colony (i.e. 87,504 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach, and between approximately 0.02 – 0.03% 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 0.099 – see Table 2.17 in the Offshore EIA Report, volume 3, appendix 11.6), the estimates of adult displacement mortality equate to an increase of less than 0.1% for the Developer Approach and of 0.2 – 0.3% for the lower and upper estimates from the Scoping Approach.
  3. The potential levels of impact on the Farne Islands SPA puffin population resulting from the mortality predicted from displacement and barrier effects associated with the Proposed Development in-combination with the other UK North Sea wind farms 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
  1. 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 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 5.129 above).
  2. 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 5.130:
Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Puffin Population Under Different Impact Scenarios for the Proposed Development In-Combination with the other UK North Sea Wind Farms

Table 5.130: Projected 35 Year Population Sizes and Associated PVA Metrics for the Farne Islands SPA Puffin Population Under Different Impact Scenarios for the Proposed Development In-Combination with the other UK North Sea Wind Farms

 

  1. 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 the other UK North Sea wind farms suggest greater population-level impacts than as predicted for the Proposed Development alone (compare Table 5.128 with Table 5.130). However, the changes in the values of the PVA metrics are small, with the reduction in the size of the SPA population after 35 years relative to that in the absence of any wind farm effects predicted to be approximately 1 - 1.5% for the Scoping Approach (compared to approximately 0.5 – 1% for the Proposed Development alone). The equivalent reduction is smaller for the metrics associated with the Developer Approach. For both the Developer and Scoping Approaches, the values for the centile metric remain close to, or above, 49 and continue to indicate a high likelihood of the impacted population being of a similar size to the un-impacted population after 35 years (Table 5.130).
In-combination: conclusion
  1. On the basis of the above considerations, it is concluded that the population-level impacts resulting from the Proposed Development in-combination with the other UK North Sea wind farms would not result in an adverse effect on the Farne Islands SPA puffin population. This conclusion applies irrespective of whether effects are determined according to the Scoping Approach or the Developer Approach.

Assessment for the breeding seabird assemblage

  1. The breeding seabird assemblage for the Farne Islands SPA is a qualifying feature on the basis of the SPA supporting in excess of 20,000 individual seabirds (with the citation stating that the SPA supports 163,819 individual seabirds). Puffin and kittiwake are amongst the species identified in the citation as having nationally important populations which contribute to the Farne Islands SPA breeding seabird assemblage, whilst guillemot is a qualifying feature in its own right. Furthermore, the scoping advice from Natural England identified herring gull, lesser black-backed gull and razorbill as further components of the assemblage feature (volume 3, appendix 6.2 of the Offshore EIA Report).
  2. Potential impacts of the Proposed Development alone and in-combination with 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, such that the SACOs to (i) maintain 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) maintain the species diversity of the breeding seabird assemblage qualifying feature are not achieved.
  3. For the Developer Approach, the assessments undertaken above identify no adverse effect in relation to any SPA populations which contribute to the assemblage feature (both for the Proposed Development alone and in-combination).
  4. However, for the Scoping Approach, the assessments identify the potential for an adverse effect on the SPA kittiwake population in relation to the Proposed Development in-combination with the other UK North Sea wind farms. The potential impact on the SPA kittiwake population is not considered likely to lead to a risk of this population being lost from the breeding seabird assemblage at the Farne Islands SPA, on the basis of the limited scale of the predicted impact (relative to the population size) and the limited extent of the existing documented decline of this population. Also, given the range of species present within the SPA seabird assemblage and their relative abundances, the potential adverse effect on the SPA kittiwake population is not considered to be sufficient to result in an adverse effect on the seabird assemblage via reductions in the overall abundance of this assemblage.
  5. Therefore, it is concluded that there is no potential for an adverse effect on the breeding seabird assemblage feature, irrespective of whether the effects are determined by the Scoping or Developer Approach.

Site conclusion

Developer approach
  1. It is concluded that there is no potential for an adverse effect on the qualifying features of the Farne Islands SPA or on the named component species of the breeding seabird assemblage qualifying feature due to the effects from the Proposed Development alone or in-combination with other plans and projects. Consequently, it is concluded that there is no potential for an Adverse Effects on Integrity of the Farne Islands SPA.
Scoping approach
  1. It is concluded that the possibility of an adverse effect cannot be discounted for the Farne Islands 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 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.
  2. Consequently, it is concluded that an Adverse Effects on Integrity of the Farne Islands SPA cannot be excluded due to effects of the Proposed Development in-combination with other plans and projects.

5.7.5.    Buchan Ness to Collieston Coast SPA

European site information and conservation objectives

  1. Buchan Ness to Collieston Coast SPA is a stretch of south-east facing cliff in Aberdeenshire, located approximately 94 km from the Proposed Development. The boundary of the SPA follows the boundaries of Bullers of Buchan Coast SSSI and Collieston to Whinnyfold Coast SSSI, and the seaward extension extends approximately 2 km into the marine environment. The SPA was classified in 1998, with the marine extension classified in 2009.
  2. The site qualifies under Article 4.2 by regularly supporting in excess of 20,000 breeding seabirds, including five named component species (Table 5.131). The potential for LSE has been identified in relation to two of these five qualifying features (Table 5.131), with the effect pathways associated with LSE for each of these detailed in Table 3.1 and set out in the assessment below.
  3. The conservation objectives of this SPA (as determined from NatureScot’s SiteLink (SiteLink (nature.scot)) are:
  • To avoid deterioration of the habitats of the qualifying species (listed below) or significant disturbance to the qualifying species, thus ensuring that the integrity of the site is maintained; and
  • To ensure for the qualifying species that the following are maintained in the long term:

–           Population of the species as a viable component of the site;

–           Distribution of the species within site;

–           Distribution and extent of habitats supporting the species;

–           Structure, function and supporting processes of habitats supporting the species; and

–           No significant disturbance of the species.

  1. Further information on this European site is presented in appendix 3A.

 

Table 5.131:
Details on the Qualifying Features of the Buchan Ness to Collieston Coast SPA

Table 5.131: Details on the Qualifying Features of the Buchan Ness to Collieston Coast SPA

*Named components of the assemblage only.

 

Assessment for the kittiwake population

  1. The Buchan Ness to Collieston Coast SPA kittiwake population is currently estimated to number 22,590 individuals, based upon the most recently available count data from 2019 (Offshore EIA Report, volume 3, appendix 11.5). This is substantially below the citation level (which is equivalent to almost 61,000 individuals - Table 5.131). The peak count from the data available on the SMP is 49,914 individuals in 1995, with subsequent data suggesting a rapid decline to levels close to the current population size by the early 2000s (SMP 2022).
The potential for impacts on the kittiwake population
  1. The Proposed Development and two kilometre buffer around the Proposed Development array area7 do not overlap with the Buchan Ness to Collieston Coast 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 to maintain, in the long term, the population of the species as a viable component of the site 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 first Conservation Objective (as for the maintain in the long term no significant disturbance of the species, because disturbance would only be considered significant if it caused an adverse effect on the population viability of the qualifying features).
  2. 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 Buchan Ness to Collieston Coast SPA could 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 1% 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.
  3. 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 Buchan Ness to Collieston Coast 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 Buchan Ness to Collieston Coast SPA kittiwake population during breeding and non-breeding periods.