Further mitigation and residual effect

451. No offshore ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 11.10) is not significant in EIA terms.

                        Puffin

452. The estimated abundance of puffin for the purpose of estimating displacement impacts is given in Table 11.54   Open ▸ . Estimated abundances for projects are those presented by Berwick Bank (SSE Renewables, 2022), for which NatureScot has not raised any concerns or noted any errors. In addition, estimates have been obtained from Green Volt Offshore Wind Farm (Green Volt, 2023), Pentland Floating Offshore Wind (Pentland Floating Offshore Wind Farm, 2022), West of Orkney (Offshore Wind Power Limited, 2023), North Falls (North Falls, 2023), Five Estuaries (Five Estuaries, 2023) and Outer Dowsing (Outer Dowsing, 2023) offshore wind farms, as those projects had not published their estimates at the time of the Berwick Bank application. As puffin disperse rapidly and widely in the non-breeding season, only the breeding season is considered for the puffin cumulative assessment.

Table 11.54: Puffin Cumulative Abundance Estimates

453. The cumulative displacement mortality is given in Table 11.55: (with Berwick Bank included) and Table 11.47   Open ▸ (with Berwick Bank excluded). Mortality is calculated using 60% displacement and a range of 3% to 5% mortality in the breeding season, in line with guidance (NatureScot, 2023h). Additionally, the Applicant’s Approach which utilises a 50% displacement rate and 1% mortality rate are presented.

Table 11.55: Puffin Cumulative Displacement Mortality Estimates Inclusive of Berwick Bank

454. With Berwick Bank, the estimated displacement mortality for puffin, following the NatureScot Approach, is 464 to 774 individuals in the breeding season. This is equivalent to an increase in baseline mortality of 0.94% to 1.57% in the breeding season (Table 11.55:).
455. When following the Applicant’s Approach, the estimated displacement mortality with Berwick Bank, for puffin is 129 individuals in the breeding season. This is equivalent to an increase in baseline mortality of 0.26% in the breeding season.

Table 11.56: Puffin Cumulative Displacement Mortality Estimates Exclusive of Berwick Bank

456. Without Berwick Bank, the estimated displacement mortality for puffin, following the NatureScot Approach, is 383 to 638 individuals in the breeding season. This is equivalent to an increase in baseline mortality of 0.78% to 1.29% in the breeding season (Table 11.56:).
457. When following the Applicant’s Approach, the estimated displacement mortality without Berwick Bank, for puffin is 106 individuals in the breeding season. This is equivalent to an increase in baseline mortality of 0.22% in the breeding season.
458. The estimated cumulative displacement mortality therefore represents an increase in mortality of over 1% of baseline mortality when applying the upper end of NatureScot’s Approach, both with and without Berwick Bank during the breeding season. Therefore, to further assess the significance of this effect, a PVA has been carried out for puffin as described in volume 3, appendix 11.5.

                        PVA Assessment Including Berwick Bank

459. During the breeding season, using the NatureScot approach (60% displacement and 5% mortality) and under the most extreme scenario with Berwick Bank included, the PVA predicted that the CPS was 0.807 ( Table 11.57   Open ▸ ). The median population size was therefore projected to be 19.30% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 34.96. In terms of the population size, this implies that the median of the impacted population fell within the 34th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was 0.994 ( Table 11.57   Open ▸ ) which translates to a median reduction of 0.59% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. However, as noted earlier within section 11.11, research examining the displacement effects on puffin indicates that a 50% displacement rate is more reflective (MacArthur Green, 2019; 2023). Consequently, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.26%. This level of impact would likely remain undetectable against natural population fluctuations. Furthermore, it would not significantly alter the background mortality rate.

Table 11.57: Puffin 35 Year Cumulative PVA Results for Displacement Impacts Including Berwick Bank during the Breeding Season

                        PVA Assessment Excluding Berwick Bank

460. During the breeding season, using the NatureScot approach (60% displacement and 5% mortality) and under the most extreme scenario with Berwick Bank excluded, the PVA predicted that the CPS was 0.838 ( Table 11.58   Open ▸ ). The median population size was therefore projected to be 16.18% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 38. In terms of the population size, this implies that the median of the impacted population fell within the 38th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was 0.995 ( Table 11.58   Open ▸ ) which translates to a median reduction of 0.49% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. As noted earlier, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.22%. This level of impact would likely remain undetectable against natural population fluctuations. Furthermore, it would not significantly alter the background mortality rate.

Table 11.58: Puffin 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank during the Breeding Season

                        Magnitude of impact

461. The estimated mortality resulting from displacement during operation and maintenance was assessed for each season, and also on an annual basis by combining seasonal impacts and comparing them against the largest regional seasonal population (as set out in volume 3, appendix 11.3, and summarised in Table 11.23   Open ▸ ).
462. Based on the PVA results using a 60% displacement and 5% mortality rate of the NatureScot Approach with Berwick Bank included the magnitude of impact on the puffin population during the breeding season is considered to be of low magnitude.
463. Based on the displacement assessment using a 60% displacement and 3% mortality rate of the NatureScot Approach with Berwick Bank included the magnitude of impact on the puffin population during the breeding season is considered to be of low magnitude.
464. Based on the displacement assessment using a 50% displacement and 1% mortality rate of the Applicant Approach with Berwick Bank included the magnitude of impact on the puffin population during the breeding season is considered to be of low magnitude.
465. Based on the PVA results using a 60% displacement and 5% mortality rate of the NatureScot Approach with Berwick Bank excluded, the magnitude of impact on the puffin population during the breeding season is considered to be of low magnitude.
466. Based on the displacement assessment using a 60% displacement and 3% mortality rate of the NatureScot Approach with Berwick Bank excluded, the magnitude of impact on the puffin population during the breeding season is considered to be of low magnitude.
467. Based on the displacement assessment using a 50% displacement and 1% mortality rate of the Applicant Approach with Berwick Bank excluded, the magnitude of impact on the puffin population during the breeding season is considered to be of low magnitude.
468. During the breeding season, the Applicant Approach is regarded as informative, particularly because the rates utilised are derived from post-construction studies conducted over multiple years (see paragraph 144 to 147). However, even under the NatureScot Approach and incorporating the most extreme scenario of 60% displacement and 5% mortality, the impact is considered to be of low magnitude, irrespective of whether Berwick Bank is included or excluded from the analysis.
469. The cumulative effect is predicted to be of national spatial extent, long-term duration, continuous and high reversibility. It is predicted that the impact will affect the receptor directly. The magnitude is therefore, considered to be low.

                        Sensitivity of the receptor

470. Puffin are considered to be moderately vulnerable to disturbance (Wade et al., 2016). Behavioural responses to underwater and airborne sounds resulting from construction activities are unknown. Although puffin are likely to respond to visual stimuli during the construction phase, the impacts of disturbance/displacement are short-term and puffin have the ability to return to the baseline abundance and distribution after construction (MacArthur Green, 2023).
471. Puffin have a low reproductive potential (i.e. typically laying only one egg and not breeding until five years old) (Robinson, 2005). Given puffin nest in burrows, and often in inaccessible locations, abundance estimates are relatively infrequent. The long-term pattern indicates a population increase since the counts conducted for Operation Seafarer (1969/70) but small declines in recent years (JNCC, 2021; Burnell, 2023). Puffin is therefore assessed as having low recoverability.
472. Puffin is a qualifying interest for several SPAs likely to be connected to the Array (within the mean-max + SD foraging range), with several non-SPA colonies also within range and so the species is considered to be of international value. The population recorded during baseline surveys of the Array was found to be of regional importance. Therefore, puffin is considered to be of international value.
473. Puffin is deemed to be of medium vulnerability, limited potential recoverability and international value. The sensitivity of the receptor is therefore considered to be high.

                        Significance of the effect

474. Overall, the magnitude of the impact is deemed to be low and the sensitivity of the receptor is considered to be high. The effect will, therefore, be of minor to moderate adverse significance. However, due to the PVA results concluding there to be a low impact both with and without Berwick Bank and following both the NatureScot and Applicant’s Approach, it is considered that minor adverse significance is appropriate, which is not significant in EIA terms.

                        Further mitigation and residual effect

475. No offshore ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 11.10) is not significant in EIA terms.

                        Razorbill

476. The estimated abundance of razorbill for the purpose of estimating displacement impacts is given in Table 11.59:. Estimated abundances for projects are those presented by Berwick Bank (SSE Renewables, 2022), for which NatureScot has not raised any concerns or noted any errors. In addition, estimates have been obtained from Green Volt Offshore Wind Farm (Green Volt, 2023), Pentland Floating Offshore Wind (Pentland Floating Offshore Wind Farm, 2022), West of Orkney (Offshore Wind Power Limited, 2023), North Falls (North Falls, 2023), Five Estuaries (Five Estuaries, 2023) and Outer Dowsing (Outer Dowsing, 2023) offshore wind farms, as those projects had not published their estimates at the time of the Berwick Bank application.

Table 11.59: Razorbill Cumulative Abundance Estimates

477. The cumulative displacement mortality is given in Table 11.60   Open ▸ (with Berwick Bank included) and Table 11.61   Open ▸ with Berwick Bank excluded). Mortality is calculated using 60% displacement and a range of 3% to 5% mortality in the breeding season and 1% to 3% mortality in the non-breeding seasons, in line with guidance (NatureScot, 2023h). Additionally, the Applicant’s Approach which utilises a 50% displacement rate and 1% mortality rate is presented.

Table 11.60: Razorbill Cumulative Displacement Mortality Estimates Inclusive of Berwick Bank

478. With Berwick Bank, the estimated displacement mortality for razorbill, following the NatureScot Approach, is 331 to 994 individuals in the pre-breeding season, 336 to 560 individuals in the breeding season, 339 to 1,016 individuals in the post-breeding season and 208 to 623 individuals in the non-breeding season. This is equivalent to an increase in baseline mortality of 0.33% to 0.97% in the pre-breeding season, 3.57% to 5.96% in the breeding season, 0.33% to 1.00% in the post-breeding season and 0.55% to 1.65% in the non-breeding season. On an annual basis, the number of mortalities is estimated as 1,213 to 3,192 individuals, which equates to an increase in baseline mortality of 1.19% to 3.13% ( Table 11.60   Open ▸ ).
479. When following the Applicant’s Approach, the estimated displacement mortality with Berwick Bank, for razorbill is 276 individuals in the pre-breeding season, 93 individuals in the breeding season, 282 individuals in the post-breeding season and 173 individuals in the non-breeding season. This is equivalent to an increase in baseline mortality of 0.27% in the pre-breeding season, 0.99% in the breeding season, 0.28% in the post-breeding season and 0.46% in the non-breeding season. On an annual basis, the number of mortalities is estimated as 825 individuals, which equates to an increase in baseline mortality of 0.81%.

Table 11.61:  Razorbill Cumulative Displacement Mortality Estimates Exclusive of Berwick Bank

480. Without Berwick Bank and using the NatureScot rates, the estimated displacement mortality for razorbill is 286 to 859 individuals in the pre-breeding season, 263 to 439 individuals in the breeding season, 286 to 857 individuals in the post-breeding season and 199 to 597 individuals in the non-breeding season. This is equivalent to an increase in baseline mortality of 0.28% to 0.84% in the pre-breeding season, 2.80% to 4.67% in the breeding season, 0.28% to 0.84% in the post-breeding season and 0.53% to 1.59% in the non-breeding season. On an annual basis, the number of mortalities is estimated as 1,034 to 2,752 individuals, which equates to an increase in baseline mortality of 1.01% to 2.70% ( Table 11.61   Open ▸ ).
481. When following the Applicant’s Approach, the estimated displacement mortality without Berwick Bank, for razorbill is 239 individuals in the pre-breeding season, 73 individuals in the breeding season, 238 individuals in the post-breeding season and 166 individuals in the non-breeding season. This is equivalent to an increase in baseline mortality of 0.23% in the pre-breeding season, 0.78% in the breeding season, 0.23% in the post-breeding season and 0.44% in the non-breeding season. On an annual basis, the number of mortalities is estimated as 716 individuals, which equates to an increase in baseline mortality of 0.70%.
482. The estimated cumulative displacement mortality therefore represents an increase in mortality of over 1% of baseline mortality when applying the NatureScot Approach range with Berwick Bank, as well as the upper range of the NatureScot Approach without Berwick Bank during the breeding season and on an annual basis. Therefore, to further assess the significance of this effect, a PVA has been carried out for razorbill as described in volume 3, appendix 11.5.

                        PVA Assessment Including Berwick Bank

483. When considering the impact during the breeding season on the regional population defined for the breeding season, using the NatureScot approach (60% displacement and 3% to 5% mortality) and with Berwick Bank included, the PVA predicted that the CPS was 0.397 to 0.212 ( Table 11.62   Open ▸ ). The median population size was therefore projected to be between 60.27% to 78.81% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 1.76 to 0. In terms of the population size, this implies that a rate of 60% displacement and 3% mortality would result in a medium impacted population that fell within the 1st percentile of the unimpacted population, with a rate of 60% displacement and 5% mortality resulting in median of the impacted population falling outside the percentile range of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that this level of impact would have an adverse effect on the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was between 0.975 to 0.958 ( Table 11.62   Open ▸ ) which translates to a median reduction of 2.53% to 4.22% in population growth rate after 35 years. Such a decrease indicates that this level of impact would adversely affect the population. As noted earlier within section 11.11, research examining the displacement effects on razorbill indicates that a 50% displacement rate is more reflective, with this rate still regarded as precautionary (RoyalHaskoning, 2013; Peschko et al. 2020; APEM, 2022; MacArthur Green, 2023). Consequently, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.99% which is below the 1% threshold and therefore would not adversely affect the population or alter background mortality rates. In addition, under the unimpacted scenario, within the PVA model, razorbill population was estimated to decline. However, the recent published Seabirds Count (Burnell et al. 2023) highlighted that overall, razorbill populations within the UK have increased by 21%, with colonies in Scotland experiencing population change of between -89% to +393% and colonies within England changing by between +64% to +230%. It's worth noting that the population models utilised in this analysis were not density dependent (to follow NatureScot guidance). As a result, population size predictions are not constrained by the model and can be predicted to grow, or decline, in unrealistic ways. While the PVA models indicate a decline in population regardless of impact, this contradicts the recently published results from the Seabirds Census (Burnell et al., 2023), which demonstrate an increase in razorbill populations despite the model predictions.

Table 11.62: Razorbill 35 Year Cumulative PVA Results for Displacement Impacts Including Berwick Bank during the Breeding Season

484. When considering the impact during the non-breeding season on the regional population defined for the non-breeding season, using the NatureScot approach (60% displacement and 3% mortality) and with Berwick Bank included, the PVA predicted that the CPS was 0.780 ( Table 11.63   Open ▸ ). The median population size was therefore projected to be 22.00% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 27.4. In terms of the population size, this implies that the median of the impacted population fell within the 27th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023) guidance. The PVA model predicted that the CPGR was 0.993 ( Table 11.63   Open ▸ ) which translates to a median reduction of 0.69% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. As stated previously, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.46%.

Table 11.63: Razorbill 35 Year Cumulative PVA Results for Displacement Impacts Including Berwick Bank during the Non-breeding Season

485. When considering the annual impact on the annual regional population, under the range of scenarios considered (60% displacement and 1% to 3% mortality) and with Berwick Bank included, the PVA predicted that the CPS was 0.844 to 0.638 ( Table 11.64   Open ▸ ). The median population size was therefore projected to be between 15.63% to 36.18% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 34.16 to 14.60. In terms of the population size, this implies that the median of the impacted population fell within the 34th and 14th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the if a 60% displacement and 3% mortality rate was applied, there could be an adverse effect to the population. However, as outlined within volume 3, appendix 11.5, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023) guidance. The PVA model predicted that the CPGR was between 0.995 to 0.988 ( Table 11.64   Open ▸ ) which translates to a median reduction of 0.47% to 1.24% in population growth rate after 35 years. Such a decrease indicates that the level of impact from a 60% displacement and 3% mortality rate could adversely affect the population. However, as stated it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.81%. This level of impact would not trigger a risk of population decline and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. Furthermore, it is not expected to significantly alter the background mortality rate.

Table 11.64: Razorbill 35 Year Cumulative PVA Results for Displacement Impacts Including Berwick Bank on an Annual Basis

                        PVA Assessment Excluding Berwick Bank

486. When considering the impact during the breeding season on the regional population defined for the breeding season, using the NatureScot approach (60% displacement and 3% to 5% mortality) and with Berwick Bank excluded, , the PVA predicted that the CPS was 0.487 to 0.298 ( Table 11.65   Open ▸ ). The median population size was therefore projected to be between 51.35% to 70.19% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 4.48 to 0.32 In terms of the population size, this implies that a rate of 60% displacement and 3% mortality would result in a medium impacted population that fell within the 4th percentile of the unimpacted population, with a rate of 60% displacement and 5% mortality resulting in median of the impacted population falling outside the percentile range of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that this level of impact would have an adverse effect on the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was between 0.980 to 0.967 ( Table 11.65   Open ▸ ) which translates to a median reduction of 1.98% to 3.31% in population growth rate after 35 years. Such a decrease indicates that this level of impact would adversely affect the population. However, as noted earlier within section 11.11, research examining the displacement effects on razorbill indicates that a 50% displacement rate is more reflective, with this rate still regarded as precautionary (Royal Haskoning, 2013; Peschko et al. 2020; APEM, 2022; MacArthur Green, 2023). Consequently, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.78% which is below the 1% threshold and therefore would therefore not adversely affect the population or alter background mortality rates. In addition, as stated previously, under the unimpacted scenario, within the PVA model, razorbill population was estimated to decline. However, the recent published Seabirds Count (Burnell et al. 2023) highlighted that overall, razorbill populations within the UK have increased by 21%, with colonies in Scotland experiencing population change of between -89% to +393% and colonies within England changing by between +64% to +230%. It's worth noting that the population models utilised in this analysis were not density dependent (to follow NatureScot guidance). As a result, population size predictions are not constrained by the model and can be predicted to grow, or decline, in unrealist ways like the population trend predicted for razorbill. While the PVA models indicate a decline in population regardless of impact, this contradicts the recently published results from the Seabirds Census (Burnell et al., 2023), which anticipate an increase in razorbill populations despite the model predictions.

Table 11.65: Razorbill 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank during the Breeding Season

487. When considering the impact during the non-breeding season on the regional population defined for the non-breeding season, using the NatureScot approach (60% displacement and 3% mortality) and with Berwick Bank excluded, the PVA predicted that the CPS was 0.809 ( Table 11.66   Open ▸ ). The median population size was therefore projected to be 19.07% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 31.04. In terms of the population size, this implies that the median of the impacted population fell within the 31st percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023) guidance. The PVA model predicted that the CPGR was 0.994 ( Table 11.66   Open ▸ ) which translates to a median reduction of 0.58% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. As stated previously, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.44%.

Table 11.66: Razorbill 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank during the Non-breeding Season

488. When considering the annual impact on the annual regional population, under the NatureScot scenarios (60% displacement, 1% to 3% mortality) and with Berwick Bank excluded, the PVA predicted that the CPS was between 0.865 to 0.679 ( Table 11.67   Open ▸ ). The median population size was therefore projected to be 13.49% to 32.11% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 36.40 to 18.04. In terms of the population size, this implies that the median of the impacted population fell within the 36th and 18th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario under the lower rate was still within the margin of error of the non-impacted scenario. Under the most extreme scenario, it fell near the lower percentile of the unimpacted population and therefore could indicate that there was an adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023) guidance. The PVA model predicted that the CPGR was 0.996 to 0.989 ( Table 11.67   Open ▸ ) which translates to a median reduction of 0.40% to 1.07% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would not trigger a risk of population decline and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. Furthermore, it is not expected to significantly alter the background mortality rate. As stated, it is anticipated that the Applicant’s approach (incorporating a 50% displacement rate alongside a 1% mortality rate) leads to an estimate that aligns more closely with actual conditions. If the Applicant’s approach is followed, the increase in baseline mortality would be 0.70%.

Table 11.67: Razorbill 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank on an Annual Basis

                        Magnitude of impact

489. The estimated mortality resulting from displacement during operation and maintenance was assessed for each season, and also on an annual basis by combining seasonal impacts and comparing them against the largest regional seasonal population (as set out in volume 3, appendix 11.3, and summarised in Table 11.22   Open ▸ ).
490. Based on the displacement assessment, for the pre-breeding and post-breeding season with Berwick Bank included and following the NatureScot Approach using a 60% displacement and 5% mortality rate, the cumulative impact was perceived to be of low magnitude.
491. Based on the displacement assessment, for the pre-breeding and post-breeding season with Berwick Bank included and following the NatureScot Approach using a 60% displacement and 3% mortality rate, the cumulative impact was perceived to be of low magnitude.
492. Based on the displacement assessment, for the pre-breeding and post-breeding season with Berwick Bank included and following the Applicant Approach using a 50% displacement and 1% mortality rate, the cumulative impact was perceived to be of low magnitude.
493. Based on the PVA results using the 60% displacement and 5% mortality rate of the NatureScot Approach and with Berwick Bank included the magnitude of impact on the razorbill population during the breeding season is considered to be of medium magnitude.
494.  Based on the PVA results using the 60% displacement and 3% mortality rate of the NatureScot Approach and with Berwick Bank included the magnitude of impact on the razorbill population during the breeding season is considered to be of medium magnitude.
495. Based on the displacement assessment, for the breeding season with Berwick Bank included and following the Applicant Approach using a 50% displacement and 1% mortality rate, the impact from the cumulative assessment was perceived to be of low magnitude.
496. Based on the PVA results using the 60% displacement and 3% mortality rate of the NatureScot Approach and with Berwick Bank included the magnitude of impact on razorbill population in the non-breeding season is considered to be of low magnitude.
497. Based on the PVA results using the 60% displacement and 1% mortality rate of the NatureScot Approach and with Berwick Bank included the magnitude of impact on razorbill population in the non-breeding season is considered to be of low magnitude.
498. Based on the displacement assessment, using the 50% displacement and 1% mortality rate of the Applicant Approach and with Berwick Bank included the magnitude of impact on razorbill population in the non-breeding season is considered to be of low magnitude.
499. Based on the PVA results, on an annual basis with Berwick Bank included and following the NatureScot Approach using a 60% displacement and 3% mortality rate, the impact from the cumulative assessment is considered to be of low magnitude.
500. Based on the PVA results, on an annual basis with Berwick Bank included and following the NatureScot Approach using a 60% displacement and 3% mortality rate, the impact on the razorbill population from the cumulative assessment is considered to be of low magnitude.
501. Based on the displacement assessment, on an annual basis with Berwick Bank included and following the Applicant Approach using a 50% displacement and 1% mortality rate, the impact on the razorbill population from the cumulative assessment is considered to be of low magnitude.
502. Based on the displacement assessment, for the pre-breeding and post-breeding season with Berwick Bank excluded and following the NatureScot Approach using a 60% displacement and 5% mortality rate, the cumulative impact was perceived to be of low magnitude.
503. Based on the displacement assessment, for the pre-breeding and post-breeding season with Berwick Bank excluded and following the NatureScot Approach using a 60% displacement and 3% mortality rate, the cumulative impact was perceived to be of low magnitude.
504. Based on the displacement assessment, for the pre-breeding and post-breeding season with Berwick Bank excluded and following the Applicant Approach using a 50% displacement and 1% mortality rate, the cumulative impact was perceived to be of low magnitude.
505. Based on the PVA results using the 60% displacement and 5% mortality rate of the NatureScot Approach and with Berwick Bank excluded, the magnitude of impact on the razorbill population during the breeding season is considered to be of medium magnitude.
506.  Based on the PVA results using the 60% displacement and 3% mortality rate of the NatureScot Approach and with Berwick Bank excluded, the magnitude of impact on the razorbill population during the breeding season is considered to be of medium magnitude.
507. Based on the displacement assessment, for the breeding season with Berwick Bank excluded and following the Applicant Approach using a 50% displacement and 1% mortality rate, the impact from the cumulative assessment was perceived to be of low magnitude.
508. Based on the PVA results using the 60% displacement and 3% mortality rate of the NatureScot Approach and with Berwick bank excluded, the magnitude of impact on razorbill population in the non-breeding season is considered to be of low magnitude.
509. Based on the displacement assessment, using the 60% displacement and 1% mortality rate of the NatureScot Approach and with Berwick Bank excluded, the magnitude of impact on razorbill population in the non-breeding season is considered to be of low magnitude.
510. Based on the displacement assessment, using the 50% displacement and 1% mortality rate of the Applicant Approach and with Berwick Bank excluded, the magnitude of impact on razorbill population in the non-breeding season is considered to be of low magnitude.
511. Based on the  PVA results, on an annual basis with Berwick Bank excluded and following the NatureScot Approach using a 60% displacement and 3% mortality rate, the impact from the cumulative assessment was perceived as low.
512. Based on the displacement assessment, on an annual basis with Berwick Bank excluded and following the NatureScot Approach using a 60% displacement and 1% mortality rate, the impact on the razorbill population from the cumulative assessment is considered to be of low magnitude.
513. Based on the displacement assessment, on an annual basis with Berwick Bank excluded and following the Applicant Approach using a 50% displacement and 1% mortality rate, the impact on the razorbill population from the cumulative assessment is considered to be of low magnitude.
514. For the breeding season, non-breeding season and annually, the Applicant Approach is regarded as informative, particularly because the rates utilised are derived from post-construction studies conducted over multiple years (see paragraph 144 to 147). The impact is therefore considered to be of low magnitude, irrespective of whether Berwick Bank is included or excluded from the analysis.
515. The cumulative effect is predicted to be of national spatial extent, long-term duration, continuous and high reversibility. It is predicted that the impact will affect the receptor directly. The magnitude is therefore, considered to be low.

                        Sensitivity of the receptor

516. As with guillemot, razorbill are deemed to be moderately vulnerable to disturbance from vessels and helicopters at offshore wind farms (Wade et al., 2016). Although razorbill are likely to respond to visual stimuli during the construction phase, the impacts of disturbance/displacement are short-term and razorbill have the ability to return to the baseline conditions after construction.
517. Although the species has a low reproductive potential (only laying one egg) and does not breed until four years old (Robinson, 2005), razorbill are deemed to have a medium recoverability given their increasing trend in abundance in the UK (JNCC, 2020).
518. The Array is within the foraging range of razorbill from two SPAs at which the species is a qualifying feature (Fowlsheugh SPA and Troup, Pennan and Lion’s Heads SPA). In addition, there are a number of smaller colonies within foraging range. The numbers of razorbills recorded during baseline surveys of the Array are considered to be of national importance. Therefore, razorbill is considered to be of international conservation value.
519. Razorbill is deemed to be of medium vulnerability, medium recoverability and international value. The sensitivity of the receptor is therefore, considered to be high.

                        Significance of the effect

520. Overall, the magnitude of the impact is deemed to be low and the sensitivity of the receptor is considered to be high. The effect will, therefore, be of minor to moderate adverse significance. However, considering both the pre-breeding season and post-breeding season mortality rates fell below 1%, along with the PVA results indicating a low impact with and without Berwick Bank, following both the NatureScot and Applicant's Approach the impact is considered minor. Additionally, the Applicant's Approach aligns more closely with displacement effects observed in guillemot populations, as evidenced by Dierschke et al. (2016), APEM (2022), MacArthur Green (2023), Royal Haskoning (2013), Leopold and Verdaat (2018), and Peschko et al. (2020 It is therefore deemed appropriate to categorise the impact as having minor adverse significance, which is not significant in EIA terms.

                        Further mitigation and residual effect

521. No offshore ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 11.10) is not significant in EIA terms.

                        Gannet

522. The estimated abundance of gannet for the purpose of estimating displacement impacts is given in Table 11.68   Open ▸ . Estimated abundances for projects are those presented by Berwick Bank (SSE Renewables, 2022), for which NatureScot has not raised any concerns or noted any errors. In addition, estimates have been obtained from Green Volt Offshore Wind Farm (Green Volt, 2023), Pentland Floating Offshore Wind (Pentland Floating Offshore Wind Farm, 2022), West of Orkney (Offshore Wind Power Limited, 2023), North Falls (North Falls, 2023), Five Estuaries (Five Estuaries, 2023) and Outer Dowsing (Outer Dowsing, 2023) offshore wind farms, as those projects had not published their estimates at the time of the Berwick Bank application.

Table 11.68: Gannet Cumulative Abundance Estimates

523. The cumulative displacement mortality is given in Table 11.69   Open ▸ (with Berwick Bank included) and Table 11.70   Open ▸ with Berwick Bank excluded. Mortality is calculated using 70% displacement and a range of 1% to 3% mortality in all seasons, in line with guidance (NatureScot, 2023h). Additionally, the Applicant’s Approach which utilises a 70% displacement rate and 1% mortality rate is presented.
524. With Berwick Bank, the estimated displacement mortality for gannet, following the NatureScot Approach, is 43 to 129 individuals in the pre-breeding season, 203 to 610 individuals in the breeding season and 182 to 545 individuals in the post-breeding season. This equates to an increase in baseline mortality of 0.09% to 0.27% in the pre-breeding season, 0.14% to 0.42% in the breeding season and 0.21% to 0.62% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 428 to 1,284, which equates to an increase in baseline mortality of 0.29% to 0.87% ( Table 11.69   Open ▸ ).
525. When following the Applicant’s Approach, the estimated displacement mortality with Berwick Bank, for gannet is 43 individuals in the pre-breeding season, 203 individuals in the breeding season and 182 individuals in the post-breeding season. This is equivalent to an increase in baseline mortality of 0.09% in the pre-breeding season, 0.14% in the breeding season and 0.21% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 428 individuals, which equates to an increase in baseline mortality of 0.29%.

Table 11.69: Gannet Cumulative Displacement Mortality Estimates Inclusive of Berwick Bank

526. Without Berwick Bank, the estimated displacement mortality for gannet, following the NatureScot Approach, is 41 to 123 individuals in the pre-breeding season, 170 to 511 individuals in the breeding season and 171 to 513 individuals in the post-breeding season. This is equivalent to an increase in baseline mortality of 0.09% to 0.26% in the pre-breeding season, 0.12% to 0.35% in the breeding season and 0.20% to 0.58% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 382 to 1,147, which equates to an increase in baseline mortality of 0.26% to 0.78% ( Table 11.70   Open ▸ ).
527. When following the Applicant’s Approach, the estimated displacement mortality without Berwick Bank, for gannet is 41 individuals in the pre-breeding season,170 individuals in the breeding season and 171 individuals in the post-breeding season. This is equivalent to an increase in baseline mortality of 0.09% in the pre-breeding season, 0.12% in the breeding season and 0.20% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 382 individuals, which equates to an increase in baseline mortality of 0.26%.
528. The estimated cumulative displacement mortality therefore represents an increase in mortality of less than 1% of baseline mortality when applying the Applicant’s Approach and NatureScot’s Approach range, both with and without Berwick Bank. Therefore, there is no cumulative effect of displacement on gannet, and PVA is not required.

Table 11.70: Gannet Cumulative Displacement Mortality Estimates Exclusive of Berwick Bank

                        Magnitude of Impact

529. The estimated mortality resulting from displacement during operation and maintenance was assessed for each season, and also on an annual basis by combining seasonal impacts and comparing them against the largest regional seasonal population (as set out in volume 3, appendix 11.3, and summarised in Table 11.25   Open ▸ ).
530. Under all seasons considered, the cumulative impact is predicted to be of low magnitude both following the NatureScot and Applicant Approach and both with and without Berwick Bank. The cumulative effect is predicted to be of national spatial extent, long-term duration, continuous and high reversibility. It is predicted that the impact will affect the receptor directly. The magnitude is therefore, considered to be low.

                        Sensitivity of the receptor

531. Gannet are considered to have a very low vulnerability to other sources of disturbance such as vessel and helicopter traffic (Wade et al., 2016), and so gannet are considered to be of very low vulnerability.
532. Gannet have low reproductive potential given a typical age of first breeding of five years and typically laying only a single egg per breeding season. However, although gannet has a low reproductive potential, the species has demonstrated a consistent increasing trend in abundance since the 1990s (JNCC, 2020). It is of note that the species has suffered from the outbreak of HPAI during the 2022 breeding season (Pearce-Higgins et al., 2023), with declines of 25% recorded at certain sites in Britain in 2023 when compared against a pre-HPAI baseline (Tremlett et al., 2024). Therefore, whilst the overall population has shown steady growth, HPAI has led to some short-term declines. Therefore, overall gannet is deemed to have low recoverability.
533. Due to the large foraging range, gannet is a qualifying interest for several SPAs likely to be connected to the Array (within the mean-max + SD foraging range), including the UK’s largest gannet colony at Bass Rock. Bass Rock, which falls within the Outer Firth of Forth and St Andrews Bay Complex SPA, located 106.4 km south-west of the Array. The species is therefore considered to be of international value. Refer to volume 3, appendix 11.1 (Table 6.30) for details of SPAs with connectivity to the Array with regards to gannet.
534. Gannet is deemed to be of very low vulnerability, low recoverability and international value. The sensitivity of the receptor is therefore considered to be high.

                        Significance of the effect

535. Overall, the magnitude of the impact is deemed to be low and the sensitivity of the receptor is considered to be high. The effect will, therefore, be of minor to moderate adverse significance. However, considering all seasonal impacts fell below 1%, the impact is considered to be of minor adverse significance, which is not significant in EIA terms.

                        Further mitigation and residual effect

536. No offshore ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 11.10) is not significant in EIA terms.

Collision with Wind Turbines

537. The Array, together with other offshore wind farms in the North Sea, may contribute to cumulative collision risk, in the event the operations and maintenance phases of different projects overlap.
538. As stated, data used within the assessing cumulative collision risk is based on published information produced by the respective project developers. As such, the input parameters (e.g. avoidance rates) and the collision risk model used (e.g. deterministic) may vary from those put forward in this chapter.
539. The species assessed for cumulative collision impacts were kittiwake, gannet and herring gull. The predicted impact for lesser black-backed gull and fulmar from the Array represented less than 0.01% of the baseline mortality of all seasonal and annual regional populations. It is therefore considered that the Array will not materially contribute to any existing cumulative collision impacts on these species.
540. Additionally, the impact to migratory species was deemed to be negligible from the Array and it is therefore concluded that the Array will not materially contribute to any existing cumulative collision impacts on these species.
541. There is no cumulative collision impact from the Proposed onshore application.