Non-breeding Season – Autumn Migration Period

725. For the Developer Approach, kittiwake cumulative displacement was not considered for the autumn migration period of the non-breeding season, for the reasons outlined in Paragraph 11.11.215.
726. For the autumn migration period of the non-breeding season, the cumulative abundance for kittiwake was 73,303 individuals ( Table 11.94   Open ▸ ). When considering the Scoping Approach displacement rate of 30%, this would affect an estimated 21,991 birds.
727. Based on information presented in Furness (2015), in the non-breeding season 47% of the population present in the autumn migration period are immature birds and 53% of birds are adults. This would mean that an estimated 10,336 kittiwakes displaced from offshore wind farms during the autumn migration period would be immature birds, with 11,655 adult birds also displaced.
728. Applying the Scoping Approach A mortality rate of 1%, it was calculated that the predicted theoretical additional mortality due to cumulative displacement effects was 220 kittiwakes (117 adults and 103 immature birds) in the autumn migration period. Based on Furness (2015), the total kittiwake BDMPS regional baseline population for the autumn migration period is estimated to be 829,937 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the estimated regional baseline mortality of kittiwakes is 132,790 birds in the autumn migration period of the non-breeding season. The additional predicted mortality of 220 kittiwakes for Scoping Approach A would increase the baseline mortality rate by 0.17% ( Table 11.99   Open ▸ ).
729. Applying the Scoping Approach B mortality rate of 3%, it was calculated that the predicted theoretical additional mortality due to cumulative displacement effects was 660 kittiwakes (350 adults and 310 immature birds) in the autumn migration period. Based on Furness (2015), the total kittiwake BDMPS regional baseline population for the autumn migration period is estimated to be 829,937 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the estimated regional baseline mortality of kittiwakes is 132,790 birds in the autumn migration period of the non-breeding season. The additional predicted mortality of 660 kittiwakes for Scoping Approach B would increase the baseline mortality rate by 0.50% ( Table 11.100   Open ▸ ).

Non-breeding Season – Spring Migration Period

730. For the Developer Approach, kittiwake displacement was not considered for the spring migration period of the non-breeding season, for the reasons outlined in Paragraph 11.11.215.
731. For the spring migration period of the non-breeding season, the cumulative abundance for kittiwake was 61,931 individuals ( Table 11.94   Open ▸ ). When considering the Scoping Approach displacement rate of 30%, this would affect an estimated 18,579 birds.
732. Based on information presented in Furness (2015), in the non-breeding season, 47% of the population present in the spring migration period are immature birds, and 53% of birds are adults. This would mean that an estimated 8,732 kittiwakes displaced from offshore wind farms during the spring migration period would be immature birds, with 9,847 adult birds also displaced.
733. Applying the Scoping Approach A mortality rate of 1%, it was calculated that the predicted theoretical additional mortality due to cumulative displacement effects was 186 kittiwakes (99 adults and 87 immature birds) in the spring migration period. Based on Furness (2015), the total kittiwake BDMPS regional baseline population for the spring migration period is estimated to be 627,816 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the estimated regional baseline mortality of kittiwakes is 100,451 birds in the spring migration period. The additional predicted mortality of 186 kittiwakes for Scoping Approach A would increase the baseline mortality rate by 0.19% ( Table 11.99   Open ▸ ).
734. Applying the Scoping Approach B mortality rate of 3%, it was calculated that the predicted theoretical additional mortality due to displacement effects was 557 kittiwakes (295 adults and 262 immature birds) in the spring migration period. Based on Furness (2015), the total kittiwake BDMPS regional baseline population for the spring migration period is estimated to be 627,816 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.160 ( Table 11.21   Open ▸ ), the estimated regional baseline mortality of kittiwakes is 100,451 birds in the spring migration period. The additional predicted mortality of 557 kittiwakes for Scoping Approach B would increase the baseline mortality rate by 0.55% ( Table 11.100   Open ▸ ).

Assessment of Displacement Mortality throughout the Year

735. Predicted kittiwake mortality as a result of cumulative displacement for all seasons as calculated above, was summed for the whole year.
736. Based on an assumed displacement rate of 30% and the Developer Approach mortality rate of 2%, the predicted theoretical additional mortality due to cumulative displacement effects was an estimated 179 breeding adult kittiwakes in the breeding season only. This corresponds to an increase in the baseline mortality rate of 0.39% ( Table 11.98   Open ▸ ).
737. Applying the Scoping Approach A displacement rate of 30% and mortality rate of 1% in the breeding and non-breeding seasons, the predicted theoretical additional annual mortality due to cumulative displacement effects was an estimated 496 kittiwakes. This corresponds to an increase in the baseline mortality rate of 0.55% ( Table 11.99   Open ▸ ).
738. Applying the Scoping Approach B displacement rate of 30% and mortality rate of 3% in the breeding and non-breeding seasons, the predicted theoretical additional annual mortality due to displacement effects was an estimated 1,486 kittiwakes. This corresponds to an increase in the baseline mortality rate of 1.63% ( Table 11.100   Open ▸ ).
739. These cumulative displacement mortality estimates did not suggest a potentially significant increase in the cumulative baseline mortality rate for kittiwake for the Developer Approach or the Scoping Approaches. However, cumulative PVA analysis for combined displacement and collision effects was conducted on the kittiwake regional SPA population. The cumulative PVA assessment for kittiwake is presented following the cumulative collision impact section of this section, from paragraph 933 onwards.

Guillemot

740. There is potential for cumulative displacement effects on guillemot. The estimated cumulative abundance of guillemots from the relevant projects are presented in Table 11.101   Open ▸ . There are a number of projects for which there are no, or limited, data on the number of guillemots predicted to be displaced, in particular, for some of the earlier Round 1 and Round 2 developments.
741. The mean maximum foraging range +1 SD for guillemot is 73.2±80.5 km. Projects within this foraging range during the breeding period are highlighted in bold in Table 11.101   Open ▸ .

Table 11.101: Cumulative Abundance of Guillemots for North Sea Offshore Wind Farm Projects (Projects in bold are within 153.7 km of Proposed Development)

742. The following displacement matrices provide, for the relevant bio-seasons, the estimated cumulative mortality of guillemots 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).
743. Each cell presents potential cumulative bird mortality following displacement from the Proposed Development and the other offshore wind farm projects during a bio-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).
744. For the Developer Approach cumulative displacement assessment, a displacement rate of 50% and a mortality rate of 1% was applied to each bio-season based on evaluation of the published literature and in line with values used by other offshore wind farm displacement assessments.
745. There were two parts to the Scoping Approach displacement assessment and these are outlined below. For Scoping Approach A, a displacement rate of 60% and mortality rates of 3% for the breeding season and 1% for the non-breeding season were applied. For Scoping Approach B, a displacement rate of 60% and mortality rates of 5% for the breeding season and 3% for the non-breeding season were applied.
746. A complete range of cumulative displacement matrices for the Proposed Development array area and 2 km buffer and other North Sea offshore wind farm projects for the different bio-seasons for both the Developer Approach and the Scoping Approach A and B are presented in Table 11.102   Open ▸ and Table 11.103   Open ▸ .

Table 11.102: Potential Cumulative Guillemot 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 boxes - Based on 60% displacement rate and 3% and 5% mortality rate (Scoping Approach A and B).

Table 11.103: Potential Cumulative Guillemot Mortality following Displacement from Offshore Wind Farms in the Non-Breeding Season

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

Magnitude of impact

747. For the Developer Approach, annual cumulative estimated guillemot mortality from displacement by Tier 2 projects was based on 50% displacement and 1% mortality, which was further broken down into the relevant bio-seasons in Table 11.104   Open ▸ . For the Scoping Approach, annual cumulative estimated guillemot mortality from displacement by Tier 2 projects was based on 60% displacement and 3% and 5% mortality in the breeding season and 1% and 3% mortality in the non-breeding season ( Table 11.105   Open ▸ ).
748. 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 within each bio-season with respect to the regional populations.

Breeding Season

749. During the breeding season, the cumulative abundance for guillemot was estimated to be 105,922 individuals ( Table 11.101   Open ▸ ). When considering the Developer Approach displacement rate of 50% this would affect an estimated 52,961 birds. However, this estimate includes non-breeding adults and immature birds, as well as breeding adults.

Table 11.104: Cumulative Displacement Mortality Estimates for Guillemot 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 and non-breeding season.

750. 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 11.33   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 guillemots from the stable age structure ( Table 11.33   Open ▸ ), 48.8% of birds present are likely to be immature birds, with 51.2% of birds likely to be adult birds. This would mean that an estimated 27,116 guillemots displaced from offshore wind farms during the breeding period would be adult birds.
751. Applying the Developer Approach mortality rate of 1%, the predicted theoretical additional mortality due to displacement effects would be 530 guillemots (271 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 guillemots 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, 19 adult guillemots were considered to be not breeding and so 252 adult breeding guillemots were taken forward for the breeding season assessment.
752. The total guillemot regional baseline breeding population is estimated to be 353,971 individuals. Using the adult baseline mortality rate of 0.073 ( Table 11.21   Open ▸ ), the predicted baseline mortality of guillemots is 25,840 adult birds per breeding season. The additional predicted mortality of 252 adult guillemots would increase the baseline mortality rate by 0.98% ( Table 11.104   Open ▸ ).
753. When considering the Scoping Approach A displacement rate of 60%, this would affect an estimated 63,553 birds ( Table 11.105   Open ▸ and Table 11.106   Open ▸ ). Assuming that 51.2% of the population present are adult birds, then this would mean that an estimated 32,539 guillemots displaced would be adult birds.
754. Applying the Scoping Approach A mortality rate of 3%, the predicted theoretical additional mortality due to cumulative displacement effects was 1,907 guillemots (976 adults) in the breeding season. Applying the 7% rate for “sabbatical” non-breeding birds, resulted in 68 birds being considered as non-breeding “sabbatical birds, with 908 adult breeding guillemots being taken forward for the breeding season assessment.
755. Using the adult baseline mortality rate of 0.073 ( Table 11.21   Open ▸ ), the predicted baseline mortality of guillemots is 25,840 adult birds per breeding season. The additional predicted mortality of 908 adult guillemots would increase the baseline mortality rate by 3.51% ( Table 11.105   Open ▸ ).

Table 11.105: Cumulative Displacement Mortality Estimates for Guillemot 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 and 1% in non-breeding season.

756. Applying the Scoping Approach B mortality rate of 5%, the predicted theoretical additional mortality due to displacement effects was 3,178 guillemots (1,627 adults) in the breeding season. Applying the 7% rate for “sabbatical” non-breeding birds, resulted in 114 birds being considered as non-breeding “sabbatical birds, with 1,513 adult breeding guillemots being taken forward for the breeding season assessment.
757. Using the adult baseline mortality rate of 0.073 ( Table 11.21   Open ▸ ), the predicted baseline mortality of guillemots is 25,840 adult birds per breeding season. The additional predicted mortality of 1,513 adult guillemots would increase the baseline mortality rate by 5.86% ( Table 11.106   Open ▸ ).

Table 11.106: Cumulative Displacement Mortality Estimates for Guillemot 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 and 3% in non-breeding season.

Non-breeding season

758. During the non-breeding season, the cumulative abundance for guillemot is 59,830 individuals ( Table 11.101   Open ▸ ). When considering the Developer Approach displacement rate of 50%, this would affect an estimated 29,915 birds ( Table 11.104   Open ▸ ). However, this estimate includes non-breeding adults and immature birds, as well as breeding adults. Based on information presented in Furness (2015), in the non-breeding season 43% of the population present are immature birds and 57% of birds are adults. This would mean that an estimated 12,863 guillemots displaced during the non-breeding season would be immature birds, with 17,052 adult birds also displaced.
759. Applying the Developer Approach mortality rate of 1%, the predicted theoretical additional mortality due to cumulative displacement effects was 299 guillemots in the non-breeding season. Scoping Opinion advice for guillemots was to use the regional breeding population within mean maximum foraging range +1S.D. as the reference population for the guillemot non-breeding season, on the basis that birds do not travel far from their breeding colonies in the non-breeding season (Buckingham et al. 2022). Therefore, the total guillemot regional baseline population in the non-breeding season, including adults and immature birds, is predicted to be 353,971 individuals.
760. Using the average baseline mortality rate of 0.148 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of guillemots is 52,388 birds in the non-breeding season. The additional predicted mortality of 299 guillemots would increase the baseline mortality rate by 0.57% ( Table 11.104   Open ▸ ).
761. When considering the Scoping Approach displacement rate of 60%, this would affect an estimated 35,898 birds ( Table 11.105   Open ▸ and Table 11.106   Open ▸ ). Based on information presented in Furness (2015), in the non-breeding season 43% of the population present are immature birds and 57% of birds are adults. This would mean that an estimated 15,436 guillemots displaced during the non-breeding season would be immature birds, with 20,462 adult birds also displaced.
762. Applying the Scoping Approach A mortality rate of 1%, it was calculated that the predicted theoretical additional mortality due to cumulative displacement effects was 359 guillemots. This additional predicted mortality would increase the baseline mortality rate by 0.69% ( Table 11.105   Open ▸ ).
763. Applying the Scoping Approach B mortality rate of 3%, it was calculated that the predicted theoretical additional mortality due to cumulative displacement effects was 1,077 guillemots. This additional predicted mortality would increase the baseline mortality rate by 2.06% ( Table 11.106   Open ▸ ).

Assessment of Displacement Mortality throughout the Year

764. Predicted guillemot mortality as a result of cumulative displacement for all seasons as calculated above, was summed for the whole year.
765. Based on the Developer Approach displacement rate of 50% and a mortality rate of 1%, the predicted theoretical cumulative annual mortality due to displacement effects was an estimated 551 guillemots. This corresponds to an increase in the baseline mortality rate of 1.55% ( Table 11.104   Open ▸ ).
766. Applying the Scoping Approach A displacement rate of 60% and mortality rate of 3% in the breeding season and 1% in the non-breeding season, the predicted theoretical cumulative mortality due to displacement effects was an estimated 1,267 guillemots. This corresponds to an increase in the baseline mortality rate of 4.2% ( Table 11.105   Open ▸ ).
767. Applying the Scoping Approach B displacement rate of 60% and mortality rate of 5% in the breeding season and 3% in the non-breeding season, the predicted theoretical cumulative mortality due to displacement effects was an estimated 2,590 guillemots. This corresponds to an increase in the baseline mortality rate of 7.92% ( Table 11.106   Open ▸ ).

Summary of PVA Assessment

768. As these cumulative displacement mortality estimates suggested a potentially significant increase in the cumulative baseline mortality rate for guillemot for North Sea offshore wind farms and both the Developer Approach and the Scoping Approach, cumulative PVA analysis was conducted on the guillemot 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.
769. The results of the PVA for predicted cumulative 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 guillemot regional SPA population for the 35-year projection is summarised in Table 11.107   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 11.107: Summary of PVA Cumulative Displacement Outputs for Guillemot 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 and non-breeding season.
Scoping Approach A = 60% displacement rate and 3% mortality rate in breeding season and 1% mortality rate in non-breeding season.
Scoping Approach B = 60% displacement rate and 5% mortality rate in breeding season and 3% mortality rate in non-breeding season.

770. For both the with and without Project scenarios, the guillemot 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 predicted to be slightly 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 very 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 the Developer Approach and other Forth and Tay consented projects on the guillemot regional SPA population after 35 years.
771. 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 also close to 1.000, while the 50th Centile value was 23.2. 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 Forth and Tay consented projects on the guillemot regional SPA population after 35 years.
772. 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 below 0.9, while the 50th Centile value was 8.6. These values indicate that the PVA did predict a negative effect from the cumulative effects of displacement mortality from Scoping Approach B and other Forth and Tay consented projects on the guillemot regional SPA population after 35 years.
773. 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 very little 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 36.6. 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 guillemot regional SPA population after 35 years.
774. 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 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 18.1, These values indicate that the PVA did not predict a significant negative effect from the cumulative effects of displacement mortality from the Scoping Approach and other North Sea consented projects on the guillemot regional SPA population after 35 years.
775. 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 larger predicted difference in the counterfactual of the population growth rate, and the counterfactual of the population size was also lower, while the 50th Centile value was 4.5. These values indicate that the PVA predicted a larger negative effect from the cumulative effects of displacement mortality from Scoping Approach B and other North Sea consented projects on the guillemot regional SPA guillemot population after 35 years.
776. Based on the results from the cumulative displacement assessment and the cumulative PVA for the Developer Approach, the magnitude of impact on the guillemot regional SPA population is low.
777. Based on the results from the cumulative displacement assessment and the cumulative PVA for Scoping Approach A, the magnitude of impact on the guillemot regional SPA population is low.
778. Based on the results from the cumulative displacement assessment and the cumulative PVA for Scoping Approach B, the magnitude of impact on the guillemot regional SPA population is medium.

Sensitivity of the receptor

779. Evidence of guillemot sensitivity to displacement from offshore wind farms is summarised in paragraph 296 onwards. Overall, on the basis of evidence from post-construction studies and reviews, guillemot sensitivity to operational offshore wind farms is considered to be medium ( Table 11.16   Open ▸ ).

Significance of the effect

780. For cumulative displacement effects for guillemot, 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.
781. 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.
782. 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

783. For the Developer Approach and Scoping Approach A, no offshore and intertidal ornithology mitigation is considered necessary because the likely cumulative 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 cumulative impact is considered to be of minor adverse significance, which is not significant in EIA terms.
784. 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.

Razorbill

785. There is potential for cumulative displacement effects on razorbills. The estimated cumulative abundance of razorbills from the relevant projects are presented in Table 11.108   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.
786. The mean maximum foraging range +1 SD for razorbill is 88.7±75.9 km. Projects within this foraging range during the breeding period are highlighted in bold in Table 11.108   Open ▸ .

Table 11.108: Cumulative Abundance of Razorbills for North Sea Offshore Wind Farm Projects (Projects in bold are within 164.6 km of Proposed Development)

787. The following displacement matrices provide, for the relevant bio-seasons, the estimated cumulative mortality of razorbills 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).
788. Each cell presents potential cumulative bird mortality following displacement from the Proposed Development and the other offshore wind farm projects during a bio-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).
789. For the Developer Approach cumulative displacement assessment, a displacement rate of 50% and a mortality rate of 1% was applied to each bio-season based on evaluation of the published literature and in line with values used by other offshore wind farm displacement assessments.
790. There were two parts to the Scoping Approach displacement assessment and these are outlined below. For Scoping Approach A, a displacement rate of 60% and mortality rates of 3% for the breeding season and 1% for the non-breeding season were applied. For Scoping Approach B, a displacement rate of 60% and mortality rates of 5% for the breeding season and 3% for the non-breeding season were applied.
791. A complete range of cumulative displacement matrices for the Proposed Development array area and 2 km buffer and other North Sea offshore wind farm projects for the different bio-seasons for both the Developer Approach and Scoping Approach A and B are presented in Table 11.109   Open ▸ to Table 11.112   Open ▸ .

Table 11.109: Potential Cumulative Razorbill 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 3% and 5% mortality rate (Scoping Approach A and B).

Table 11.110: Potential Cumulative Razorbill Mortality following Displacement from Offshore Wind Farms in the Autumn Migration Period of the Non-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).

Table 11.111: Potential Cumulative Razorbill Mortality following Displacement from Offshore Wind Farms in the Winter Period of the Non-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).

Table 11.112: Potential Cumulative Razorbill Mortality following Displacement from Offshore Wind Farms in the Spring Migration Period of the Non-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

792. For the Developer Approach, annual cumulative estimated razorbill mortality from displacement by Tier 2 projects was based on 50% displacement and 1% mortality, which was further broken down into the relevant bio-seasons in Table 11.113   Open ▸ . For the Scoping Approach, annual cumulative estimated razorbill mortality from displacement by Tier 2 projects was based on 60% displacement and 3% and 5% mortality in the breeding season and 1% and 3% mortality in the non-breeding season ( Table 11.114   Open ▸ ).
793. 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 within each bio-season with respect to the regional populations.

Breeding Season

794. During the breeding season, the cumulative abundance for razorbill was estimated to be 15,735 individuals ( Table 11.108   Open ▸ ). When considering the Developer Approach displacement rate of 50% this would affect an estimated 7,868 birds. However, this estimate includes non-breeding adults and immature birds, as well as breeding adults.

Table 11.113: Cumulative Displacement Mortality Estimates for Razorbill 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 and non-breeding season.

795. 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 11.38   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 razorbills from the stable age structure ( Table 11.38   Open ▸ ), 46.6% of birds present are likely to be immature birds, with 53.4% of birds likely to be adult birds. This would mean that an estimated 4,202 razorbills displaced from offshore wind farms during the breeding period would be adult birds.
796. Applying the Developer Approach mortality rate of 1%, the predicted theoretical additional mortality due to displacement effects would be 79 razorbills (42 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 razorbills 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, three adult razorbills were considered to be not breeding and so 39 adult breeding razorbills were taken forward for the breeding season assessment.
797. The total razorbill regional baseline breeding population is estimated to be 84,501 individuals. Using the adult baseline mortality rate of 0.09 ( Table 11.21   Open ▸ ), the predicted baseline mortality of razorbills is 7,605 adult birds per breeding season. The additional predicted mortality of 39 adult razorbills would increase the baseline mortality rate by 0.51% ( Table 11.113   Open ▸ ).
798. When considering the Scoping Approach displacement rate of 60%, this would affect an estimated 9,441 birds ( Table 11.114   Open ▸ and Table 11.115   Open ▸ ). Assuming that 53.4% of the population present are adult birds, then this would mean that an estimated 5,041 razorbills displaced would be adult birds.
799. Applying the Scoping Approach A mortality rate of 3%, the predicted theoretical additional mortality due to cumulative displacement effects was 283 razorbills (151 adults) in the breeding season. Applying the 7% rate for “sabbatical” non-breeding birds, resulted in 11 birds being considered as non-breeding “sabbatical birds, with 140 adult breeding razorbills being taken forward for the breeding season assessment.
800. Using the adult baseline mortality rate of 0.09 ( Table 11.21   Open ▸ ), the predicted baseline mortality of razorbills is 7,605 adult birds per breeding season. The additional predicted mortality of 140 adult razorbills would increase the baseline mortality rate by 1.84% ( Table 11.114   Open ▸ ).

Table 11.114: Cumulative Displacement Mortality Estimates for Razorbill 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 and 1% in non-breeding season.

801. Applying the Scoping Approach B mortality rate of 5%, the predicted theoretical additional mortality due to displacement effects was 472 razorbills (252 adults) in the breeding season. Applying the 7% rate for “sabbatical” non-breeding birds, resulted in 18 birds being considered as non-breeding “sabbatical birds, with 234 adult breeding razorbills being taken forward for the breeding season assessment.
802. Using the adult baseline mortality rate of 0.09 ( Table 11.21   Open ▸ ), the predicted baseline mortality of razorbills is 7,605 adult birds per breeding season. The additional predicted mortality of 234 adult razorbills would increase the baseline mortality rate by 3.08% ( Table 11.115   Open ▸ ).

Table 11.115: Cumulative Displacement Mortality Estimates for Razorbill 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 and 3% in non-breeding season.

Autumn Migration Period of Non-breeding Season

803. For the autumn migration period of the non-breeding season, the cumulative mean peak abundance of razorbills was 51,834 individuals ( Table 11.108   Open ▸ ). When considering the Developer Approach displacement rate of 50%, this would affect an estimated 25,917 birds ( Table 11.113   Open ▸ ).
804. Applying the Developer Approach mortality rate of 1%, the predicted theoretical additional mortality due to displacement effects was 259 razorbills in the autumn migration period. Based on Furness (2015), the total razorbill BDMPS regional baseline population for the autumn migration period is predicted to be 591,874 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 71,025 birds in the autumn migration period of the non-breeding season. The additional predicted mortality of 259 razorbills would increase the baseline mortality rate by 0.36% ( Table 11.113   Open ▸ ).
805. When considering the Scoping Approach displacement rate of 60% this would affect an estimated 31,100 birds ( Table 11.114   Open ▸ and Table 11.115   Open ▸ ). Applying the Scoping Approach A mortality rate of 1%, the predicted theoretical additional mortality due to cumulative displacement effects was 311 razorbills in the autumn migration period. Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 71,025 birds in the autumn migration period of the non-breeding season. The additional predicted mortality of 311 razorbills would increase the baseline mortality rate by 0.44% ( Table 11.114   Open ▸ ).
806. Applying the Scoping Approach B mortality rate of 3%, the predicted theoretical additional mortality due to cumulative displacement effects was 933 razorbills in the autumn migration period. Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 71,025 birds in the autumn migration period of the non-breeding season. The additional predicted mortality of 933 razorbills would increase the baseline mortality rate by 1.31% ( Table 11.115   Open ▸ ).

Winter Period of Non-breeding Season

807. For the winter period of the non-breeding season, the cumulative mean peak abundance of razorbills was 27,278 individuals ( Table 11.108   Open ▸ ). When considering the Developer Approach displacement rate of 50%, this would affect an estimated 13,639 birds ( Table 11.113   Open ▸ ).
808. Applying the Developer Approach mortality rate of 1%, the predicted theoretical additional mortality due to displacement effects was 136 razorbills in the winter period. Based on Furness (2015), the total razorbill BDMPS regional baseline population for the winter period is predicted to be 218,622 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 26,235 birds in the winter period of the non-breeding season. The additional predicted mortality of 136 razorbills would increase the baseline mortality rate by 0.52% ( Table 11.113   Open ▸ ).
809. When considering the Scoping Approach displacement rate of 60% this would affect an estimated 16,367 birds ( Table 11.114   Open ▸ and Table 11.115   Open ▸ ). Applying the Scoping Approach A mortality rate of 1%, the predicted theoretical additional mortality due to cumulative displacement effects was 164 razorbills in the winter period. Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 26,235 birds in the winter period of the non-breeding season. The additional predicted mortality of 164 razorbills would increase the baseline mortality rate by 0.63% ( Table 11.114   Open ▸ ).
810. Applying the Scoping Approach B mortality rate of 3%, the predicted theoretical additional mortality due to cumulative displacement effects was 491 razorbills in the winter period. Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 26,235 birds in the winter period of the non-breeding season. The additional predicted mortality of 491 razorbills would increase the baseline mortality rate by 1.87% ( Table 11.115   Open ▸ ).

Spring Migration Period of Non-breeding Season

811. For the spring migration period of the non-breeding season, the cumulative mean peak abundance of razorbills was 40,803 individuals ( Table 11.108   Open ▸ ). When considering the Developer Approach displacement rate of 50%, this would affect an estimated 20,402 birds ( Table 11.113   Open ▸ ).
812. Applying the Developer Approach mortality rate of 1%, the predicted theoretical additional mortality due to displacement effects was 204 razorbills in the spring migration period. Based on Furness (2015), the total razorbill BDMPS regional baseline population for the spring migration period is predicted to be 591,874 individuals ( Table 11.9   Open ▸ ). Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 71,025 birds in the spring migration period of the non-breeding season. The additional predicted mortality of 204 razorbills would increase the baseline mortality rate by 0.29% ( Table 11.113   Open ▸ ).
813. When considering the Scoping Approach displacement rate of 60% this would affect an estimated 24,482 birds ( Table 11.114   Open ▸ and Table 11.115   Open ▸ ). Applying the Scoping Approach A mortality rate of 1%, the predicted theoretical additional mortality due to cumulative displacement effects was 245 razorbills in the spring period. Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 71,025 birds in the spring migration period of the non-breeding season. The additional predicted mortality of 245 razorbills would increase the baseline mortality rate by 0.34% ( Table 11.114   Open ▸ ).
814. Applying the Scoping Approach B mortality rate of 3%, the predicted theoretical additional mortality due to displacement effects was 734 razorbills in the spring period. Using the average baseline mortality rate of 0.120 ( Table 11.21   Open ▸ ), the predicted regional baseline mortality of razorbills is 71,025 birds in the spring migration period of the non-breeding season. The additional predicted mortality of 734 razorbills would increase the baseline mortality rate by 1.03% ( Table 11.115   Open ▸ ).

Assessment of Displacement Mortality throughout the Year

815. Predicted razorbill mortality as a result of cumulative displacement for all seasons as calculated above, was summed for the whole year.
816. Based on the Developer Approach displacement rate of 50% and a mortality rate of 1%, the predicted theoretical cumulative annual mortality due to displacement effects was an estimated 638 razorbills. This corresponds to an increase in the baseline mortality rate of 1.68% ( Table 11.113   Open ▸ ).
817. Applying the Scoping Approach A displacement rate of 60% and mortality rate of 3% in the breeding season and 1% in the non-breeding season, the predicted theoretical cumulative mortality due to displacement effects was an estimated 860 razorbills. This corresponds to an increase in the baseline mortality rate of 3.25% ( Table 11.114   Open ▸ ).
818. Applying the Scoping Approach B displacement rate of 60% and mortality rate of 5% in the breeding season and 3% in the non-breeding season, the predicted theoretical cumulative mortality due to displacement effects was an estimated 2,392 razorbills. This corresponds to an increase in the baseline mortality rate of 7.29% ( Table 11.115   Open ▸ ).

Summary of PVA Assessment

819. As these cumulative displacement mortality estimates suggested a potentially significant increase in the cumulative baseline mortality rate for razorbill for North Sea offshore wind farms and both the Developer Approach and the Scoping Approach, cumulative PVA analysis was conducted on the razorbill 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.
820. 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 razorbill regional SPA population for the 35-year projection is summarised in Table 11.116   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 11.116: Summary of PVA Cumulative Displacement Outputs for Razorbill 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 and non-breeding season.
Scoping Approach A = 60% displacement rate and 3% mortality rate in breeding season and 1% mortality rate in non-breeding season.
Scoping Approach B = 60% displacement rate and 5% mortality rate in breeding season and 3% mortality rate in non-breeding season.

821. For both the with and without Project scenarios, the razorbill 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 slightly 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 very 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 the Developer Approach and other Forth and Tay consented projects on the razorbill regional SPA population after 35 years.
822. 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 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 Forth and Tay consented projects on the razorbill regional SPA population after 35 years.
823. 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 also close to 1.000, while the 50th Centile value was 35.1, These values indicate that the PVA did predict a slight negative effect from the cumulative effects of displacement mortality from Scoping Approach B and other Forth and Tay consented projects on the razorbill regional SPA population after 35 years.
824. 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 a 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 the Developer Approach and other North Sea consented projects on the razorbill regional SPA population after 35 years.
825. 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 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 28.7. These values indicate that the PVA did predict a slight negative effect from the cumulative effects of displacement mortality from Scoping Approach A and other North Sea consented projects on the razorbill regional SPA population after 35 years.
826. For Scoping Approach B with other North Sea consented projects, there was a larger difference between the end population size with Project scenario compared to 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 0.900, while the 50th Centile value was 14.0. These values indicate that the PVA did predict a negative effect from the cumulative effects of displacement mortality from Scoping Approach B and other North Sea consented projects on the razorbill regional SPA population after 35 years.
827. Based on the results from the cumulative displacement assessment and the cumulative PVA for the Developer Approach, the magnitude of impact on the razorbill regional SPA population is low.
828. Based on the results from the cumulative displacement assessment and the cumulative PVA for Scoping Approach A, the magnitude of impact on the razorbill regional SPA population is low.
829. Based on the results from the cumulative displacement assessment and the cumulative PVA for Scoping Approach B, the magnitude of impact on the razorbill regional SPA population is medium.