PVA Assessment Excluding Berwick Bank

422. When considering the impact during the breeding season on the regional population defined for the breeding season, using the NatureScot approach (60% displacement and 5% mortality) and with Berwick Bank excluded, the PVA predicted that the CPS was 0.409 ( Table 11.51   Open ▸ ). The median population size was therefore projected to be 59.08% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 0. In terms of the population size, this implies that the median of the impacted population falls 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, with an impact rate of 60% displacement and 5% mortality causing a population decline. 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 (2023k) guidance. The PVA model predicted that the CPGR was 0.976 ( Table 11.51   Open ▸ ) which translates to a median reduction of 2.45% 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, 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 0.25%. This level of impact would likely remain undetectable against natural population fluctuations. Furthermore, it would not significantly alter the background mortality rate.

Table 11.51: Guillemot 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank during the Breeding Season

423. 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 0.749 ( Table 11.52   Open ▸ ). The median population size was therefore projected to be 25.06% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 9.00. In terms of the population size, this implies that the median of the impacted population fell within the 9th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This level of impact could 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 0.992 ( Table 11.52   Open ▸ ) which translates to a median reduction of 0.80% 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 0.83%. In addition, the guillemot population in the UK North Sea & Channel waters BDMPS is observed to be growing and the population is still expected to continue to grow and will be larger after 35 years than that which is currently recorded, even in the event of the largest impact.

Table 11.52: Guillemot 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank during the Non-breeding Season

424. When considering the annual impact on the annual regional population, under the range of scenarios considered (60% displacement, 1% to 3% mortality) and with Berwick Bank excluded, the PVA predicted that the CPS was 0.874 to 0.708 ( Table 11.53   Open ▸ ). The median population size was therefore projected to be between 12.60% to 29.19% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 27.56 to 5.04. In terms of the population size, this implies that the median of the impacted population fell within the 27th and 5th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that, if a 60% displacement and 3% mortality rate was applied, this level of impact could have an adverse effect on 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 0.996 to 0.991 ( Table 11.53   Open ▸ ) which translates to a median reduction of 0.37% to 0.95% 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 0.97%. In addition, the guillemot population in the UK North Sea & Channel waters BDMPS is observed to be growing and the population is still expected to continue to grow and will be larger after 35 years than that which is currently recorded, even in the event of the largest impact.

Table 11.53: Guillemot 35 Year Cumulative PVA Results for Displacement Impacts Excluding Berwick Bank on an Annual Basis

                        Magnitude of impact

425. 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 11.21   Open ▸ ).
426. Based on the PVA results for the breeding season with Berwick Bank included and following the NatureScot Approach using the 60% displacement, 5% mortality rate, the magnitude of impact on the guillemot population during the breeding season is considered to be of medium magnitude.
427. Based on the PVA results for the breeding season with Berwick Bank included and following the NatureScot Approach using the 60% displacement, 3% mortality rate the magnitude of impact on the guillemot population during the breeding season is considered to be of medium magnitude.
428. 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 cumulative impact was perceived as low magnitude.
429. Based on the PVA results for the non-breeding season with Berwick Bank included and following the NatureScot Approach using the 60% displacement, 3% mortality rate, the magnitude of impact on the guillemot population during the non-breeding season is considered to be of low magnitude.
430. Based on the PVA results for the non-breeding season with Berwick Bank included and following the NatureScot Approach using the 60% displacement, 1% mortality rate, the magnitude of impact on the guillemot population during the non-breeding season is considered to be of low magnitude.
431. Based on the displacement assessment, for the non-breeding season with Berwick Bank included and following the Applicant Approach using a 50% displacement and 1% mortality rate, the cumulative impact was perceived as low magnitude.
432. 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 guillemot population on an annual basis is considered to be of low magnitude.
433. 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 the guillemot population on an annual basis is considered to be of low magnitude.
434. Based on the PVA results using the Applicant’s Approach of 50% displacement and 1% mortality and with Berwick Bank included the magnitude of impact on guillemot population on an annual basis is considered to be of low magnitude.
435. Based on the PVA results for the breeding season with Berwick Bank excluded and following the NatureScot Approach using the 60% displacement, 5% mortality rate, the magnitude of impact on the guillemot population during the breeding season is considered to be of medium magnitude.
436. Based on the displacement assessment for the breeding season with Berwick Bank excluded and following the NatureScot Approach using the 60% displacement and 3% mortality, the magnitude of impact on guillemot population during the breeding season is considered to be of low magnitude.
437. 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 cumulative impact was perceived as low magnitude.
438. Based on the PVA results for the non-breeding season with Berwick Bank excluded and following the NatureScot Approach using the 60% displacement, 3% mortality rate, the magnitude of impact on the guillemot population during the non-breeding season is considered to be of low magnitude.
439. Based on the displacement assessment for the non-breeding season with Berwick Bank excluded and following the NatureScot Approach using the 60% displacement and 1% mortality, the magnitude of impact on guillemot population during the non-breeding season is considered to be of low magnitude.
440. Based on the displacement assessment, for the non-breeding season with Berwick Bank and following the Applicant Approach using a 50% displacement and 1% mortality rate, the cumulative impact was perceived as low magnitude.
441. 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 guillemot population on an annual basis is considered to be of low magnitude.
442. Based on the PVA results using the 60% displacement and 1% mortality rate of the NatureScot Approach and with Berwick Bank excluded, the magnitude of impact on the guillemot population on an annual basis is considered to be of low magnitude.
443. Based on the displacement assessment using the Applicant’s Approach of 50% displacement and 1% mortality and with Berwick Bank excluded, the magnitude of impact on guillemot population on an annual basis is considered to be of low magnitude.
444. For all seasons, 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 considered to be of low magnitude, irrespective of whether Berwick Bank is included or excluded from the analysis.
445. Due to the minimal level of change to baseline conditions, 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

446. Guillemot are considered to be moderately vulnerable to disturbance (Wade et al., 2016). Whilst there is evidence from studies that guillemot respond adversely to vessel traffic (Rojek et al., 2007), behavioural response to underwater and airborne sounds resulting from construction activities are unknown. Although guillemot are likely to respond to visual stimuli during the construction phase, the impacts of disturbance/displacement are short-term and guillemot have the ability to return to the baseline abundance and distribution after construction.
447. Guillemot raise a single chick per year and breed from the age of six onwards, typically living on average for 23 years (Burnell et al., 2023). Guillemot have undergone decreases of approximately 31% in Scotland since the early 2000s. Surveys managed by the RSPB in 2023 have recorded indicative decreases of 6% across a number of sites in Britain in 2023 when compared against a pre-HPAI baseline (Tremlett et al., 2024). Overall, Guillemot is deemed to have low recoverability.
448. Guillemot 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, guillemot is considered to be of international value.
449. Guillemot is deemed to be of medium vulnerability, low recoverability and international value. The sensitivity of the receptor is therefore, considered to be high.

                        Significance of the effect

450. 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 the Applicant’s Approach (the approach deemed more in line with displacement effects observed by the species based on evidence; Dierschke et al., 2016; APEM, 2022; MacArthur Green, 2023; RoyalHaskoning, 2013; Leopold and Verdaat, 2018; Peschko et al., 2020) it is considered that minor adverse significance is appropriate, which is not significant in EIA terms.

                        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