Sensitivity of the receptor

830. Evidence of razorbill sensitivity to displacement from offshore wind farms is summarised in paragraph 352 onwards. Overall, on the basis of evidence from post-construction studies and reviews, razorbill sensitivity to operational offshore wind farms is considered to be medium ( Table 11.16   Open ▸ ).

Significance of the effect

831. For cumulative displacement effects for razorbill, for the Developer Approach, for the Developer Approach, the magnitude of the cumulative impact is deemed to be low, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
832. For Scoping Approach A, the magnitude of the cumulative impact is deemed to be low, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
833. For Scoping Approach B, the magnitude of the cumulative impact is deemed to be medium, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of moderate adverse significance, which is significant in EIA terms.

Secondary and Tertiary Mitigation and Residual Effect

834. For the Developer Approach and Scoping Approach A, no offshore and intertidal ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond designed in measures outlined in section 11.10) is not significant in EIA terms. Therefore, the residual impact is considered to be of minor adverse significance, which is not significant in EIA terms.
835. For Scoping Approach B, the residual cumulative impact is considered to be of moderate adverse significance, which is significant in EIA terms. However, it is considered that the displacement mortality rates used in Scoping Approach B are likely to be highly precautionary, for the reasons outlined in volume 3, appendix 11.4. Consequently, no additional mitigation is proposed.

Puffin

836. There is potential for cumulative displacement effects on puffins. The estimated cumulative abundance of puffins from the relevant projects are presented in Table 11.117   Open ▸ . There are a number of projects for which there are no, or limited, data on the number of razorbills predicted to be displaced, in particular, for some of the earlier Round 1 and Round 2 developments.
837. The mean maximum foraging range +1 SD for puffin is 137.1±128.3 km. Projects within this foraging range during the breeding period are highlighted in bold in Table 11.117   Open ▸ .

Table 11.117: Cumulative Abundance of Puffins for North Sea offshore wind farm Projects (Projects in bold are within 265.4 km of Proposed Development)

838. The following displacement matrix ( Table 11.118   Open ▸ ) provides, for the breeding season only, the estimated cumulative mortality of puffins predicted to occur due to displacement, as determined by the relevant specified rates of displacement and mortality. The approach used for the cumulative displacement assessment follows that of the project alone displacement assessment (see volume 3, appendix 11.4).
839. Each cell presents potential cumulative bird mortality following displacement from the Proposed Development and the other offshore wind farm projects in the breeding season. The outputs highlighted in colour are those based on the displacement and mortality rates used in the Developer Approach (highlighted in orange) and used in the Scoping Approach (highlighted in dark teal). Outputs highlighted in light teal reflect potential uncertainty associated with the selected figures. No adjustments for age classes of birds have been made. Further details are presented in volume 3, appendix 11.4).
840. For the Developer Approach cumulative displacement assessment, a displacement rate of 50% and a mortality rate of 1% were applied for the breeding season only, based on evaluation of the published literature and in line with values used by other offshore wind farm displacement assessments.
841. There were two parts to the Scoping Approach cumulative displacement assessment and these are outlined below. For Scoping Approach A, a displacement rate of 60% and a mortality rate of 3% were applied for the breeding season only. For Scoping Approach B, a displacement rate of 60% and a mortality rate of 5% were applied for the breeding season only.

Table 11.118: Potential Cumulative Puffin Mortality following Displacement from Offshore Wind Farms in the Breeding Season

Orange box - Based on 50% displacement rate and 1% mortality rate (Developer Approach).
Dark teal box - Based on 60% displacement rate and 1% and 3% mortality rate (Scoping Approach A and B).

Magnitude of impact

842. For the Developer Approach, cumulative estimated puffin mortality from displacement by Tier 2 projects was based on 50% displacement and 1% mortality, for the breeding season only ( Table 11.119   Open ▸ ). For the Scoping Approach, cumulative estimated puffin mortality from displacement by Tier 2 projects was based on 60% displacement and 1% and 3% mortality in the breeding season only ( Table 11.120   Open ▸ ).
843. The overall baseline mortality rates were based on age-specific demographic rates and age class proportions as presented in Table 11.21   Open ▸ . The potential magnitude of impact was estimated by calculating the increase in cumulative baseline mortality for the breeding season with respect to the regional populations.

Breeding Season

844. During the breeding season, the cumulative abundance for puffin was estimated to be 23,756 individuals ( Table 11.117   Open ▸ ). When considering the Developer Approach displacement rate of 50% this would affect an estimated 11,878 birds. However, this estimate includes non-breeding adults and immature birds, as well as breeding adults.

Table 11.119: Cumulative Displacement Mortality Estimates for Puffin for Tier 2 projects by bio-season for Developer Approach

1 Breeding season assessment is for breeding adults only.
2 Mortality is 1% in breeding season.

845. Studies have shown that for several seabird species, in addition to breeding birds, colonies are also attended by many immature individuals and a smaller number of non-breeding adults (e.g. Wanless et al., 1998). There is little information on the breakdown of immature and non-breeding adults present at a colony, however, using proportions from the stable age structure calculated from the population models from which PVAs were produced ( Table 11.43   Open ▸ ) (volume 3, appendix 11.6). the estimated proportion of immature, non-breeding birds across all wind farms was estimated. Based on the proportion of immature puffins, 50.3% of birds present are likely to be immature birds, with 49.7% of birds likely to be adult birds. This would mean that an estimated 5,903 puffins displaced from offshore wind farms during the breeding period would be adult birds.
846. Applying the Developer Approach mortality rate of 1%, the predicted cumulative theoretical additional mortality due to displacement effects would be 119 puffins (59 adults) in the breeding season. However, a proportion of adult birds present at colonies in the breeding season will opt not to breed in a particular breeding season. It has been estimated that 7% of adult puffins may be “sabbatical” birds in any particular breeding season (volume 3, appendix 11.6), and this has been applied for this assessment. On this basis, four adult puffins were considered to be not breeding and so 55 adult breeding puffins were taken forward for the breeding season assessment.
847. The total puffin regional baseline breeding population is estimated to be 233,550 individuals. Using the adult baseline mortality rate of 0.099 ( Table 11.21   Open ▸ ), the predicted baseline mortality of puffins is 23,121 adult birds per breeding season. The additional predicted mortality of 55 adult puffins would increase the baseline mortality rate by 0.24% ( Table 11.119   Open ▸ ).
848. When considering the Scoping Approach displacement rate of 60%, this would affect an estimated 14,254 birds ( Table 11.120   Open ▸ and Table 11.121   Open ▸ ). Assuming that 49.7% of the population present are adult birds, then this would mean that an estimated 7,084 puffins displaced would be adult birds.
849. Applying the Scoping Approach A mortality rate of 3%, the predicted theoretical additional mortality due to cumulative displacement effects was 428 puffins (213 adults) in the breeding season. Applying the 7% rate for “sabbatical” non-breeding birds, resulted in 15 birds being considered as non-breeding “sabbatical birds, with 198 adult breeding puffins being taken forward for the breeding season assessment.
850. Using the adult baseline mortality rate of 0.099 ( Table 11.21   Open ▸ ), the predicted baseline mortality of puffins is 23,121 adult birds per breeding season. The additional predicted mortality of 198 adult puffins would increase the baseline mortality rate by 0.86% ( Table 11.120   Open ▸ ).

Table 11.120: Cumulative Displacement Mortality Estimates for Puffin for Tier 2 projects by bio-season for Scoping Approach A

1 Breeding season assessment is for breeding adults only.
2 Mortality is 3% in breeding season.

851. Applying the Scoping Approach B mortality rate of 5%, the predicted theoretical additional mortality due to cumulative displacement effects was 713 puffins (354 adults) in the breeding season. Applying the 7% rate for “sabbatical” non-breeding birds, resulted in 25 birds being considered as non-breeding “sabbatical birds, with 329 adult breeding puffins being taken forward for the breeding season assessment.
852. Using the adult baseline mortality rate of 0.099 ( Table 11.21   Open ▸ ), the predicted baseline mortality of puffins is 23,121 adult birds per breeding season. The additional predicted mortality of 329 adult puffins would increase the baseline mortality rate by 1.42% ( Table 11.121   Open ▸ ).

Table 11.121: Cumulative Displacement Mortality Estimates for Puffin for Tier 2 projects by bio-season for Scoping Approach B

1 Breeding season assessment is for breeding adults only.
2 Mortality is 5% in breeding season.

853. For the Developer Approach and Scoping Approach A, the cumulative displacement mortality estimate did not indicate a potential significant increase in the baseline mortality rate for puffin. However, for Scoping Approach B, the cumulative displacement mortality estimate did suggest a potential significant increase in the baseline mortality rate for puffin therefore cumulative PVA analysis was conducted on the puffin regional SPA population.

Summary of PVA Assessment

854. As these cumulative displacement mortality estimates suggested a potentially significant increase in the cumulative baseline mortality rate for puffin for North Sea offshore wind farms and both the Developer Approach and the Scoping Approach, cumulative PVA analysis was conducted on the puffin regional SPA population. The cumulative PVA analysis was carried out considering a range of cumulative displacement and mortality rates as well as a range of scenarios.
855. The results of the cumulative PVA for predicted displacement impacts for the Developer Approach and Scoping Approach with both other Forth and Tay consented projects and other North Sea consented projects during the operation phase for the puffin regional SPA population for the 35-year projection is summarised in Table 11.122   Open ▸ . Further details of the PVA methodology, input parameters and an explanation of how to interpret the PVA results can be found in volume 3, appendix 11.6.

Table 11.122: Summary of PVA Cumulative Displacement Outputs for Puffin for the Proposed Development array area and a 2 km buffer after 35 years

1 Starting population taken from volume 3, appendix 11.6.
Developer Approach = 50% displacement rate and 1% mortality rate in breeding season.
Scoping Approach A = 60% displacement rate and 3% mortality rate in breeding season.
Scoping Approach B = 60% displacement rate and 5% mortality rate in breeding season.

856. For both the with and without Project scenarios, the puffin regional SPA population is predicted to increase over the 35-year period. For the Developer Approach with other North Sea consented projects, the end population size with Project scenario was lower than the without Project scenario. There was no predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was also close to 1.000, while the 50th Centile value was very close to 50. These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement mortality from the Developer Approach and other North Sea consented projects on the puffin regional SPA population after 35 years.
857. For Scoping Approach A with other North Sea consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a very slight predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was also close to 1.000, while the 50th Centile value was close to 50. These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement mortality from Scoping Approach A and other North Sea consented projects on the puffin regional SPA population after 35 years.
858. For Scoping Approach B with other North Sea consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a very slight predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was also close to 1.000, while the 50th Centile value was relatively close to 50. These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement mortality from Scoping Approach B and other North Sea consented projects on the puffin regional SPA population after 35 years.
859. Based on the results from the cumulative displacement assessment and the cumulative PVA for the Developer Approach and other North Sea projects, the magnitude of impact on the puffin regional SPA population is negligible.
860. Based on the results from the cumulative displacement assessment and the cumulative PVA for Scoping Approach A and other North Sea projects, the magnitude of impact on the puffin regional SPA population is negligible.
861. Based on the results from the cumulative displacement assessment and the cumulative PVA for Scoping Approach B and other North Sea projects, the magnitude of impact on the puffin regional SPA population is low.

Sensitivity of the receptor

862. Evidence of puffin sensitivity to displacement from offshore wind farms is summarised in paragraph 384 onwards. Overall, on the basis of evidence from post-construction studies and reviews, puffin sensitivity to operational offshore wind farms is considered to be medium ( Table 11.16   Open ▸ ).

Significance of the effect

863. For cumulative displacement effects for puffin, for the Developer Approach, the magnitude of the cumulative impact is deemed to be negligible, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of negligible to minor adverse significance, which is not significant in EIA terms.
864. For Scoping Approach A, the magnitude of the impact is deemed to be negligible, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of negligible to minor adverse significance, which is not significant in EIA terms.
865. For Scoping Approach B, the magnitude of the impact is deemed to be low, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.

Secondary and Tertiary Mitigation and Residual Effect

866. No offshore and intertidal ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond designed in measures outlined in section 11.10) is not significant in EIA terms. Therefore, the residual impact is considered to be of not more than minor adverse significance, which is not significant in EIA terms.

Decommissioning phase

867. Cumulative effects in the decommissioning phase were scoped out in Table 11.86   Open ▸ and so are not considered further here.

Collision effects from wind turbines during operation phase

Tier 1

868. For the cumulative displacement assessment, there are no cumulative displacement impacts for Tier 1 alone.

Tier 2

Construction phase

869. Cumulative effects in the construction phase were scoped out in Table 11.86   Open ▸ and so are not considered further here.

Operation and maintenance phase

Gannet

870. The cumulative estimated number of collisions per bio-season for gannet are presented in Table 11.123   Open ▸ . For the Proposed Development, two sets of figures are presented: the Developer Approach (based on mean densities) and the Scoping Approach (based on maximum densities), for the breeding and non-breeding seasons, based on the maximum design scenario (307x14 MW wind turbines). Estimated collisions for gannet for other relevant North Sea offshore wind farm projects are also presented.

Magnitude of Impact

871. The overall baseline mortality rates were based on age-specific demographic rates and age class proportions as presented in Table 11.21   Open ▸ . The potential magnitude of impact was estimated by calculating the increase in baseline mortality within each bio-season with respect to the regional populations.

Table 11.123: Estimated Cumulative Collisions for Gannet by bio-season for Tier 2 Projects based on Consented Scenarios. (Estimates are rounded to nearest whole bird).

Table 11.124: Estimated Cumulative Numbers of Collisions for Gannet for Tier 2 projects by bio-season for Developer Approach

1 Breeding season assessment is for breeding adults only.

Table 11.125: Estimated Cumulative Numbers of Collisions for Gannet for Tier 2 projects by bio-season for Scoping Approach

1 Breeding season assessment is for breeding adults only.

Breeding Season

872. The total cumulative estimated number of gannet collisions based on North Sea offshore wind farm consented estimates and the Development Approach during the breeding season was 1,011 birds ( Table 11.123   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. For the purposes of this assessment, the estimated proportion of immature, non-breeding gannets across all wind farms was based on the age breakdown calculated for the Berwick Bank PVA study (see volume 3, appendix 11.6). Based on this breakdown, 46.4% of birds present are likely to be immature birds, with 53.6% of birds likely to be adult birds. This would mean that 542 collisions would involve adult gannets during the breeding period.
873. However, a proportion of adult birds present at colonies in the breeding season will opt not to breed in a particular breeding season. It has been estimated that 10% of adult gannets may be “sabbatical” birds in any particular breeding season (volume 3, appendix 11.6), and this has been applied for this assessment. On this basis, 54 adult gannets were considered to be not breeding and so 488 adult breeding gannets were taken forward for the breeding season assessment.
874. The total gannet regional baseline breeding population is estimated to be 323,836 individuals. Using the adult baseline mortality rate of 0.046 ( Table 11.21   Open ▸ ), the predicted baseline mortality of gannets is 14,896 adult birds per breeding season. The additional predicted mortality of 488 adult gannets would increase the baseline mortality rate by 3.28% ( Table 11.124   Open ▸ ).
875. The total cumulative estimated number of gannet collisions based on North Sea offshore wind farm consented estimates and the Scoping Approach during the breeding season was 1,043 birds ( Table 11.123   Open ▸ ). For the purposes of this assessment, the estimated proportion of immature, non-breeding gannets across all wind farms was based on the age breakdown calculated for the Berwick Bank PVA study (see volume 3, appendix 11.6). Based on this breakdown, 46.4% of birds present are likely to be immature birds, with 53.6% of birds likely to be adult birds. This would mean that 559 collisions would involve adult gannets during the breeding period. Applying the 10% rate for “sabbatical” non-breeding birds, resulted in 56 birds being considered as non-breeding “sabbatical birds, with 503 adult breeding gannets being taken forward for the breeding season assessment.
876. Using the adult baseline mortality rate of 0.046 ( Table 11.21   Open ▸ ), the predicted baseline mortality of gannets is 14,896 adult birds per breeding season. The additional predicted mortality of 503 adult gannets would increase the baseline mortality rate by 3.38% ( Table 11.125   Open ▸ ).

Autumn Migration Period of Non-breeding Season

877. The total cumulative estimated number of gannet collisions based on North Sea offshore wind farm consented estimates and the Development Approach during the autumn migration period of the non-breeding season was 710 birds ( Table 11.123   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 45% of the population present are immature birds and 55% of birds are adults. Based on this breakdown, 391 collisions would involve adult gannets, and 319 collisions would involve immature birds.
878. Based on Furness (2015), the total gannet BDMPS regional baseline population for the autumn migration period is predicted to be 456,298 individuals. Using the average baseline mortality rate of 0.151 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of gannets is 68,901 birds in the autumn migration period. The additional predicted mortality of 710 gannets of all ages would increase the baseline mortality rate by 1.03% ( Table 11.124   Open ▸ ).
879. The total cumulative estimated number of gannet collisions based on North Sea offshore wind farm consented estimates and the Scoping Approach during the autumn migration period of the non-breeding season was 715 birds ( Table 11.123   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 45% of the population present are immature birds and 55% of birds are adults. Based on this breakdown, 393 collisions would involve adult gannets, and 322 collisions would involve immature birds.
880. Using the average baseline mortality rate of 0.151 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of gannets is 68,901 birds in the autumn migration period. The additional predicted mortality of 715 gannets of all ages would increase the baseline mortality rate by 1.04% ( Table 11.125   Open ▸ ).

Spring Migration Period of Non-breeding Season

881. The total cumulative estimated number of gannet collisions based on North Sea offshore wind farm consented estimates and the Development Approach during the spring migration period of the non-breeding season was 237 birds ( Table 11.123   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 45% of the population present are immature birds and 55% of birds are adults. Based on this breakdown, 391 collisions would involve 130 adult gannets, and 107 collisions would involve immature birds.
882. Based on Furness (2015), the total gannet BDMPS regional baseline population for the spring migration period is predicted to be 248,835 individuals. Using the average baseline mortality rate of 0.151 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of gannets is 37,506 birds in the spring migration period. The additional predicted mortality of 237 gannets of all ages would increase the baseline mortality rate by 0.63% ( Table 11.124   Open ▸ ).
883. The total cumulative estimated number of gannet collisions based on North Sea offshore wind farm consented estimates and the Scoping Approach during the autumn migration period of the non-breeding season was 238 birds ( Table 11.123   Open ▸ ). Based on information presented in Furness (2015), in the non-breeding season 45% of the population present are immature birds and 55% of birds are adults. Based on this breakdown, 131 collisions would involve adult gannets, and 107 collisions would involve immature birds.
884. Using the average baseline mortality rate of 0.151 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of gannets is 37,506 birds in the spring migration period. The additional predicted mortality of 238 gannets of all ages would increase the baseline mortality rate by 0.63% ( Table 11.125   Open ▸ ).

Assessment of Cumulative Collision Mortality throughout the Year

885. Predicted gannet mortality as a result of cumulative collisions for North Sea offshore wind farms and the Developer and Scoping approaches for the Proposed Development for all bio-seasons as calculated above, was summed for the whole year.
886. Based on cumulative collisions for North Sea offshore wind farms and the Developer Approach, the predicted theoretical additional annual cumulative mortality due to collision was an estimated 1,435 gannets. This corresponds to an increase in the baseline mortality rate of 4.94% ( Table 11.124   Open ▸ ).
887. Based on cumulative collisions for North Sea offshore wind farms and the Scoping Approach, the predicted theoretical additional annual mortality due to collision was an estimated 1,456 gannets. This corresponds to an increase in the baseline mortality rate of 5.05% ( Table 11.125   Open ▸ ).

Cumulative Collision and Displacement Impacts Combined

888. NS advice in the Scoping Opinion was that collision and displacement impacts should be considered as additive within the assessment for gannet. The totals from the collision and displacement cumulative assessments for gannet were therefore combined, using the annual predicted mortality totals for both the Developer Approach and the Scoping Approach.

Table 11.126: Combined Cumulative Annual Estimated Mortality from Collisions and Displacement for Gannet for North Sea offshore wind farms and the Proposed Development array area for the Developer Approach

Table 11.127: Combined Cumulative Annual Estimated Mortality from Collisions and Displacement for Gannet for North Sea offshore wind farms and the Proposed Development array area for the Scoping Approach

889. Based on estimated combined cumulative collision and displacement mortality from North Sea offshore wind farms and the Developer Approach, the predicted theoretical additional annual mortality due to collision and displacement was a combined total of 1,728 gannets. This corresponds to an increase in the baseline mortality rate of 5.88% ( Table 11.126   Open ▸ ).
890. Based on estimated combined cumulative collision and displacement mortality from North Sea offshore wind farms and the Scoping Approach, the predicted theoretical additional annual mortality due to collision and displacement was a combined total of between 1,749 and 2,233 gannets. This corresponds to an increase in the baseline mortality rate of between 5.99% and 7.87% ( Table 11.127   Open ▸ ).
891. It should be noted that this approach is considered highly precautionary. As highlighted by NS in the NnG Scoping Opinion (Marine Scotland, 2017a), collision risk and displacement are considered to be mutually exclusive impacts, and therefore combining mortality estimates for displacement and collision should be considered extremely precautionary.

Summary of PVA Assessment

892. As these cumulative collision mortality estimates suggested a potentially significant increase in the cumulative baseline mortality rate for North Sea offshore wind farms and both the Developer Approach and the Scoping Approach, cumulative PVA analysis was conducted on the gannet regional SPA population. The cumulative PVA analysis was carried out considering a range of cumulative displacement and mortality rates as well as a range of cumulative collision scenarios.
893. The results of the cumulative PVA for predicted displacement and collision impacts for the Developer Approach and Scoping Approach with both other Forth and Tay consented projects and other North Sea consented projects during the operation phase for the gannet regional SPA population for the 35-year projection is summarised in Table 11.128   Open ▸ . Further details of the PVA methodology, input parameters and an explanation of how to interpret the PVA results can be found in volume 3, appendix 11.6.

Table 11.128: Summary of PVA Cumulative Displacement and Collision Outputs for Gannet for the Proposed Development array area after 35 years

1 Starting population taken from volume 3, appendix 11.6.
Developer Approach = 70% displacement rate and 1% mortality rate throughout the year; CRM based on mean monthly density.
Scoping Approach A = 70% displacement rate and 1% mortality rate throughout the year; CRM based on maximum monthly density.
Scoping Approach B = 70% displacement rate and 3% mortality rate throughout the year; CRM based on maximum monthly density.

894. For both the with and without Project scenarios, the gannet regional SPA population is predicted to increase over the 35-year period. For the Developer Approach with other Forth and Tay consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was 37.2, These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from the Developer Approach and other Forth and Tay consented projects on the gannet regional SPA population after 35 years.
895. For Scoping Approach A with other Forth and Tay consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was 36.9, These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from Scoping Approach A and other Forth and Tay consented projects on the gannet regional SPA population after 35 years.
896. For Scoping Approach B with other Forth and Tay consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight difference in the counterfactual of the population growth rate, and the counterfactual of the population size was below 0.900, while the 50th Centile value was 32.1, These values indicate that the PVA did predict a slight negative effect from the cumulative effects of displacement and collision mortality from Scoping Approach B and other Forth and Tay consented projects on the gannet regional SPA population after 35 years.
897. For the Developer Approach with other North Sea as-built projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was relatively close to 50, These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from the Developer Approach and other North Sea as-built projects on the gannet regional SPA population after 35 years.
898. For Scoping Approach A with other North Sea as-built projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was relatively close to 50, These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from Scoping Approach A and other North Sea as-built projects on the gannet regional SPA population after 35 years.
899. For Scoping Approach B with other North Sea as-built projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was relatively close to 50, These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from Scoping Approach B and other North Sea as-built projects on the gannet regional SPA population after 35 years.
900. Based on the results from the cumulative displacement and collision assessment and the cumulative displacement and collision PVA for the Developer Approach, the magnitude of impact on the regional SPA gannet population is low.
901. Based on the results from the cumulative displacement and collision assessment and the cumulative displacement and collision PVA for Scoping Approach A, the magnitude of impact on the regional SPA gannet population is low.
902. Based on the results from the cumulative displacement and collision assessment and the cumulative displacement and collision PVA for Scoping Approach B, the magnitude of impact on the regional SPA gannet population is medium.

Sensitivity of the receptor

903. Gannet sensitivity to displacement is discussed in paragraph 209 onwards. Based on evidence from other operational offshore wind farms and a review of gannet GPS tracking data from the Bass Rock, it is considered that the majority of adult gannets passing through the Proposed Development are in transit rather than actively foraging. In addition, the home range of birds breeding on the Bass Rock is very large, in relation to the size of the Proposed Development, while gannets are also known to feed on a wide range of prey species.
904. Based on evidence from post-construction studies, it is considered that collision impacts as estimated for the CRM assessment for gannet are likely to be over-estimates, as it is highly likely that the majority of gannets will avoid the Proposed Development.
905. On the basis of these results, which highlight the high degree of avoidance of wind turbines, gannet sensitivity to collision and displacement impacts from operational offshore wind farms is considered to be medium ( Table 11.16   Open ▸ ).

Significance of the effect

906. For cumulative displacement and collision effects for gannet, for the Developer Approach, the magnitude of the impact is deemed to be low, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
907. For Scoping Approach A, the magnitude of the impact is deemed to be low, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
908. For Scoping Approach B, the magnitude of the impact is deemed to be medium, and the sensitivity of the receptor is considered to be medium. The effect will, therefore, be of moderate adverse significance, which is significant in EIA terms.

Secondary and Tertiary Mitigation and Residual Effect

909. For the Developer Approach and Scoping Approach A, no offshore and intertidal ornithology mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond designed in measures outlined in section 11.10) is not significant in EIA terms. Therefore, the residual impact is considered to be of minor adverse significance, which is not significant in EIA terms.
910. For Scoping Approach B, the residual cumulative impact is considered to be of moderate adverse significance, which is significant in EIA terms. However, it is considered that the combined displacement and collision mortality estimates used in Scoping Approach B are highly precautionary, for the reasons outlined in paragraph 454 and also in volume 3, appendix 11.3. Consequently, no additional mitigation is proposed.

Kittiwake

911. The cumulative estimated number of collisions per bio-season for kittiwake are presented in Table 11.129   Open ▸ . For the Proposed Development, two sets of figures are presented: the Developer Approach (based on mean densities) and the Scoping Approach (based on maximum densities), for the breeding and non-breeding seasons, based on the maximum design scenario (307x14 MW wind turbines). Estimated collisions for kittiwakes for other relevant North Sea offshore wind farm projects are also presented.

Magnitude of Impact

912. The overall baseline mortality rates were based on age-specific demographic rates and age class proportions as presented in Table 11.21   Open ▸ . The potential magnitude of impact was estimated by calculating the increase in baseline mortality within each bio-season with respect to the regional populations.

Table 11.129: Estimated Cumulative Collisions for Kittiwake by bio-season for Tier 2 Projects based on Consented Scenarios. (Estimates are rounded to nearest whole bird).

Table 11.130: Estimated Cumulative Numbers of Collisions for Kittiwake for Tier 2 projects by bio-season for Developer Approach

1 Breeding season assessment is for breeding adults only.

Table 11.131: Estimated Cumulative Numbers of Collisions for Kittiwake for Tier 2 projects by bio-season for Scoping Approach

1 Breeding season assessment is for breeding adults only.

Breeding Season

913. The total cumulative estimated number of kittiwake collisions based on North Sea offshore wind farm consented estimates and the Development Approach during the breeding season was 1,258 birds ( Table 11.129   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. For the purposes of this assessment, the estimated proportion of immature, non-breeding kittiwakes across all wind farms was based on the age breakdown calculated for the Berwick Bank PVA study (see volume 3, appendix 11.6). Based on this breakdown, 46% of birds present are likely to be immature birds, with 54% of birds likely to be adult birds. This would mean that 679 collisions would involve adult kittiwakes during the breeding period.
914. However, a proportion of adult birds present at colonies in the breeding season will opt not to breed in a particular breeding season. It has been estimated that 10% of adult kittiwakes may be “sabbatical” birds in any particular breeding season (volume 3, appendix 11.6), and this has been applied for this assessment. On this basis, 68 adult kittiwakes were considered to be not breeding and so 611 adult breeding kittiwakes were taken forward for the breeding season assessment.
915. The total kittiwake regional baseline breeding population is estimated to be 319,126 individuals. Using the adult baseline mortality rate of 0.145 ( Table 11.21   Open ▸ ), the predicted baseline mortality of kittiwakes is 46,273 adult birds per breeding season. The additional predicted mortality of 611 adult kittiwakes would increase the baseline mortality rate by 1.32% ( Table 11.130   Open ▸ ).
916. The total cumulative estimated number of kittiwake collisions based on North Sea offshore wind farm consented estimates and the Scoping Approach during the breeding season was 1,449 birds ( Table 11.129   Open ▸ ). For the purposes of this assessment, the estimated proportion of immature, non-breeding kittiwakes across all wind farms was based on the age breakdown calculated for the Berwick Bank PVA study (see volume 3, appendix 11.6). Based on this breakdown, 46% of birds present are likely to be immature birds, with 54% of birds likely to be adult birds. This would mean that 782 collisions would involve adult kittiwakes during the breeding period.
917. Applying the 10% rate for “sabbatical” non-breeding birds, resulted in 78 birds being considered as non-breeding “sabbatical birds, with 704 adult breeding kittiwakes being taken forward for the breeding season assessment.
918. Using the adult baseline mortality rate of 0.145 ( Table 11.21   Open ▸ ), the predicted baseline mortality of kittiwakes is 46,273 adult birds per breeding season. The additional predicted mortality of 704 adult kittiwakes would increase the baseline mortality rate by 1.52% ( Table 11.131   Open ▸ ).

Autumn Migration Period of Non-breeding Season

919. The total cumulative estimated number of kittiwake collisions based on North Sea offshore wind farm consented estimates and the Development Approach during the autumn migration period of the non-breeding season was 990 birds ( Table 11.129   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 47% of the population present are immature birds and 53% of birds are adults. Based on this breakdown, 525 collisions would involve adult kittiwakes, and 465 collisions would involve immature birds.
920. Based on Furness (2015), the total kittiwake BDMPS regional baseline population for the autumn migration period is predicted to be 829,937 individuals. Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of kittiwakes is 132,790 birds in the autumn migration period. The additional predicted mortality of 990 kittiwakes of all ages would increase the baseline mortality rate by 0.75% ( Table 11.130   Open ▸ ).
921. The total cumulative estimated number of kittiwake collisions based on North Sea offshore wind farm consented estimates and the Scoping Approach during the autumn migration period of the non-breeding season was 1,025 birds ( Table 11.129   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 47% of the population present are immature birds and 53% of birds are adults. Based on this breakdown, 543 collisions would involve adult kittiwakes, and 482 collisions would involve immature birds.
922. Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of kittiwakes is 132,790 birds in the autumn migration period. The additional predicted mortality of 1,025 kittiwakes of all ages would increase the baseline mortality rate by 0.77% ( Table 11.131   Open ▸ ).

Spring Migration Period of Non-breeding Season

923. The total cumulative estimated number of kittiwake collisions based on North Sea offshore wind farm consented estimates and the Development Approach during the spring migration period of the non-breeding season was 932 birds ( Table 11.129   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 47% of the population present are immature birds and 53% of birds are adults. Based on this breakdown, 494 collisions would involve adult kittiwakes, and 438 collisions would involve immature birds.
924. Based on Furness (2015), the total kittiwake BDMPS regional baseline population for the spring migration period is predicted to be 627,816 individuals. Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of kittiwakes is 100,451 birds in the spring migration period. The additional predicted mortality of 932 kittiwakes of all ages would increase the baseline mortality rate by 0.93% ( Table 11.130   Open ▸ ).
925. The total cumulative estimated number of kittiwake collisions based on North Sea offshore wind farm consented estimates and the Scoping Approach during the spring migration period of the non-breeding season was 1,007 birds ( Table 11.129   Open ▸ ). However, this includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 47% of the population present are immature birds and 53% of birds are adults. Based on this breakdown, 534 collisions would involve adult kittiwakes, and 473 collisions would involve immature birds.
926. Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of kittiwakes is 100,451 birds in the spring migration period. The additional predicted mortality of 1,007 kittiwakes of all ages would increase the baseline mortality rate by 1.00% ( Table 11.131   Open ▸ ).

Assessment of Cumulative Collision Mortality throughout the Year

927. Predicted kittiwake mortality as a result of cumulative collisions for North Sea offshore wind farms and the Developer and Scoping approaches for the Proposed Development for all bio-seasons as calculated above, was summed for the whole year.
928. Based on cumulative collisions for North Sea offshore wind farms and the Developer Approach, the predicted theoretical additional annual cumulative mortality due to collision was an estimated 2,533 kittiwakes. This corresponds to an increase in the baseline mortality rate of 3.0% ( Table 11.130   Open ▸ ).
929. Based on cumulative collisions for North Sea offshore wind farms and the Scoping Approach, the predicted theoretical additional annual mortality due to collision was an estimated 2,736 kittiwakes. This corresponds to an increase in the baseline mortality rate of 3.29% ( Table 11.131   Open ▸ ).
930. These cumulative collision mortality estimates suggest a potential significant increase in the baseline mortality rate for kittiwakes resulting from cumulative collision impacts for North Sea offshore wind farms and both the Developer Approach and the Scoping Approach, therefore cumulative PVA analysis was conducted on the kittiwake regional SPA population.

Summary of PVA Assessment

931. As these cumulative collision mortality estimates suggested a potentially significant increase in the cumulative baseline mortality rate for North Sea offshore wind farms and both the Developer Approach and the Scoping Approach, cumulative PVA analysis was conducted on the kittiwake regional SPA population. The cumulative PVA analysis was carried out considering a range of cumulative displacement and mortality rates as well as a range of cumulative collision scenarios.
932. The results of the cumulative PVA for predicted displacement and collision impacts for the Developer Approach and Scoping Approach with both other Forth and Tay consented projects and other North Sea consented projects during the operation phase for the kittiwake regional SPA population for the 35-year projection is summarised in Table 11.132   Open ▸ . Further details of the PVA methodology, input parameters and an explanation of how to interpret the PVA results can be found in volume 3, appendix 11.6.

Table 11.132: Summary of PVA Cumulative Displacement and Collision Outputs for Kittiwake for the Proposed Development array area after 35 years

1 Starting population taken from volume 3, appendix 11.6.
Developer Approach = 30% displacement and 2% mortality rate in breeding season; CRM based on mean monthly density.
Scoping Approach A = 30% displacement rate and 1% mortality rate throughout the year; CRM based on maximum monthly density.
Scoping Approach B = 30% displacement rate and 3% mortality rate throughout the year; CRM based on maximum monthly density.

933. For kittiwake, the cumulative PVA predicted that the regional SPA end population would be lower than the start population for both the with and without Project scenarios over the 35-year period. For the Developer Approach, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was close to 50. These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from the Developer Approach and other Forth and Tay consented projects on the kittiwake regional SPA population after 35 years.
934. For Scoping Approach A with other Forth and Tay consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was close to 50. These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from Scoping Approach A and other Forth and Tay consented projects on the kittiwake regional SPA population after 35 years.
935. For Scoping Approach B with other Forth and Tay consented projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was close to 1.000, while the 50th Centile value was close to 50. These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement and collision mortality from Scoping Approach B and other Forth and Tay consented projects on the kittiwake regional SPA population after 35 years.
936. For the Developer Approach with other North Sea as-built projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was below 0.9.000, while the 50th Centile value was 31.2. These values indicate that the PVA did predict a slight negative effect from the cumulative effects of displacement and collision mortality from the Developer Approach and other North Sea as-built projects on the kittiwake regional SPA population after 35 years.
937. For Scoping Approach A with other North Sea as-built projects, the end population size with Project scenario was lower than the without Project scenario. There was a slight predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was below 0.9.000, while the 50th Centile value was 29.8. These values indicate that the PVA did predict a negative effect from the cumulative effects of displacement and collision mortality from the Scoping Approach and other North Sea as-built projects on the kittiwake regional SPA population after 35 years.
938. For Scoping Approach B with other North Sea as-built projects, the end population size with Project scenario was lower than the without Project scenario. There was a larger predicted decrease in the counterfactual of the population growth rate, and the counterfactual of the population size was below 0.9.000, while the 50th Centile value was 22.7. These values indicate that the PVA did predict a negative effect from the cumulative effects of displacement and collision mortality from the Scoping Approach and other North Sea as-built projects on the kittiwake regional SPA population after 35 years.
939. Based on the results from the cumulative displacement and collision assessments and the cumulative PVA for the Developer Approach, the magnitude of impact on the kittiwake regional SPA population is low.
940. Based on the results from the cumulative displacement and collision assessments and the cumulative PVA for Scoping Approach A, the magnitude of impact on the kittiwake regional SPA population is low.
941. Based on the results from the cumulative displacement and collision assessments and the cumulative PVA for Scoping Approach B, the magnitude of impact on the kittiwake regional SPA population is medium.