Further mitigation and residual effect

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

Collision with Wind Turbines

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

Tier 1 and Tier 2

Kittiwake

The estimated collision mortalities of kittiwake for the purpose of estimating cumulative collisions impacts are given in Table 11.71 Open ▸ . Estimated collisions for projects are those presented by Berwick Bank (SSE Renewables, 2022), for which NatureScot has not raised any concerns or noted any errors. In addition, estimates have been obtained from Green Volt Offshore Wind Farm (Green Volt, 2023), Pentland Floating Offshore Wind (Pentland Floating Offshore Wind Farm, 2022), West of Orkney (Offshore Wind Power Limited, 2023), North Falls (North Falls, 2023), Five Estuaries (Five Estuaries, 2023) and Outer Dowsing (Outer Dowsing, 2023) offshore wind farms, as those projects had not published their estimates at the time of the Berwick Bank application.

Table 11.71: Kittiwake Cumulative Collision Mortalities

Project	Avoidance Rate used in Assessment	Season
	Avoidance Rate used in Assessment	Breeding	Post-breeding	Pre-breeding
Aberdeen	98.9%	9.02	4.44	0.84
Beatrice	98.9%	52.11	5.89	21.90
Blyth Demo Phase 1	98.9%	1.70	2.30	1.40
Blyth Demo Phase 2 and 3	unknown	-	-	-
Dogger Bank A and B	98.9%	288.60	135.00	295.40
Dogger C and Sofia	98.9%	136.90	90.70	216.90
Dudgeon	98.9%	N/A (outside foraging range)	0.00	0.00
Dudgeon Extension and Sheringham Shoal Extension	99.2%	N/A (outside foraging range)	4.30	0.90
East Anglia 1 North	98.9%	N/A (outside foraging range)	8.10	3.50
East Anglia 2	98.9%	N/A (outside foraging range)	5.40	7.40
East Anglia 3	98.9%	N/A (outside foraging range)	56.60	30.70
East Anglia One	98.9%	N/A (outside foraging range)	108.21	31.57
Five Estuaries	99.3%	N/A (outside foraging range)	7.88	5.52
Forthwind Demonstration Project	-	-	-	-
Galloper	98.9%	N/A (outside foraging range)	11.69	13.37
Gunfleet Sands 3 Demonstration Project	unknown	N/A (outside foraging range)	-	-
Green Volt Offshore Wind Farm	99.2%	5.65	5.95	3.55
Hornsea Project Four	98.9%	75.50	13.90	4.60
Hornsea Project One	98.9%	N/A (outside foraging range)	9.72	3.63
Hornsea Project Three	98.9%	N/A (outside foraging range)	38.47	30.66
Hornsea Project Two	98.9%	N/A (outside foraging range)	9.00	3.00
Humber Gateway	98.9%	N/A (outside foraging range)	1.37	0.81
Hywind	98.9%	16.60	0.90	0.90
Inch Cape Offshore Wind Farm	98.9%	40.00	26.00	6.00
Kentish Flats	unknown	N/A (outside foraging range)	0.90	0.70
Kentish Flats + Extension	98.9%	N/A (outside foraging range)	0.00	1.60
Kincardine Offshore Wind Farm	98.9%	22.00	9.00	1.00
Lincs	98.9%	N/A (outside foraging range)	1.20	0.70
London Array	98.9%	N/A (outside foraging range)	0.88	0.69
Moray East	98.9%	24.00	2.00	5.00
Moray West	98.9%	77.00	23.00	7.00
Neart na Gaoithe	98.9%	8.00	17.00	2.00
Norfolk Boreas	98.9%	N/A (outside foraging range)	32.20	11.90
North Falls (PEIR)	98.9%	N/A (outside foraging range)	19.10	19.10
Norfolk Vanguard	98.9%	N/A (outside foraging range)	16.40	19.30
Outer Dowsing	99.3%	N/A (outside foraging range)	2.80	2.60
Pentland Floating Offshore Wind	98.9%	N/A (outside foraging range)	1.00	0.00
Race Bank	98.9%	1.12	14.08	3.30
Rampion	98.9%	N/A (outside foraging range)	N/A (outside BDMPS)	N/A (outside BDMPS)
Rampion 2	99.3%	N/A (outside foraging range)	N/A (outside BDMPS)	N/A (outside BDMPS)
Seagreen 1 and 1A Offshore Wind Farm	98.9%	62.00	70.00	38.00
Sheringham Shoal	unknown	N/A (outside foraging range)	0.00	0.00
Teesside	98.9%	32.42	20.27	2.11
Thanet	98.9%	N/A (outside foraging range)	0.23	0.18
Triton Knoll	98.9%	N/A (outside foraging range)	50.48	16.49
West of Orkney	99.3%	16.59	15.34	21.05
Westermost Rough	98.9%	0.10	0.20	0.10
Total	-	869.31	841.89	835.38
Berwick Bank	98.9%	617.00	190.00	179.00
Ossian	99.3%	28.13	5.35	6.24
Total (including Berwick Bank)	-	1514.44	1037.24	1020.62
Total (excluding Berwick Bank)	-	897.44	847.24	841.62

The cumulative collision mortality is given in Table 11.72 Open ▸ (with Berwick Bank included) and Table 11.73 Open ▸ (with Berwick Bank excluded).

Table 11.72: Kittiwake Cumulative Collision Mortality Estimates Inclusive of Berwick Bank

Season	Regional Baseline		Cumulative Collision Mortality	Increase in Baseline Mortality (%)
Season	Population	Baseline Mortality	Cumulative Collision Mortality	Increase in Baseline Mortality (%)
Pre-breeding	627,816	98,065	1,020.62	1.041
Breeding	261,047	40,776	1,514.44	3.712
Post-breeding	829,937	129,636	1,037.24	0.800
Annual	829,937	129,636	3,572.30	2.756

With Berwick Bank, the estimated collision mortality for kittiwake is 1,021 individuals in the pre-breeding season, 1,514 in the breeding season and 1,037 in the post-breeding season. This is equivalent to an increase in baseline mortality of 1.04% in the pre-breeding season, 3.71% in the breeding season and 0.80% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 3,572, which equates to an increase in baseline mortality of 2.76% ( Table 11.72 Open ▸ ).

Table 11.73: Kittiwake Cumulative Collision Mortality Estimates Exclusive of Berwick Bank

Season	Regional Baseline		Cumulative Collision Mortality	Increase in Baseline Mortality (%)
Season	Population	Baseline Mortality	Cumulative Collision Mortality	Increase in Baseline Mortality (%)
Pre-breeding	627,816	98,065	841.62	0.858
Breeding	261,047	40,776	897.44	2.201
Post-breeding	829,937	129,636	847.24	0.654
Annual	829,937	129,636	2,586.30	1.995

Without Berwick Bank, the estimated collision mortality for kittiwake is 842 individuals in the pre-breeding season, 897 in the breeding season and 847 in the post-breeding season. This is equivalent to an increase in baseline mortality of 0.86% in the pre-breeding season, 2.20% in the breeding season and 0.65% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 2,586 individuals, which equates to an increase in baseline mortality of 2.00% ( Table 11.73 Open ▸ ).
The cumulative collision mortality therefore represents an increase in mortality of over 1% of baseline mortality during the pre-breeding, breeding season and annually with Berwick Bank and the breeding season and annually excluding Berwick Bank. Therefore, to further assess the significance of this effect, a PVA has been carried out for kittiwake as described in volume 3, appendix 11.5.

PVA Assessment Including Berwick Bank

When considering the impact during the pre-breeding season on the regional population defined for the pre-breeding season, using the NatureScot avoidance rates (0.993 avoidance) and with Berwick Bank included, the PVA predicted that the CPS was 0.891 ( Table 11.74 Open ▸ ). The median population size was therefore projected to be 10.94% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 42.92. In terms of the population size, this means that the median of the impacted population fell within the 42nd percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as outlined within volume 3, appendix 11.5, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was 0.997 ( Table 11.74 Open ▸ ) which translates to a median reduction of 0.32% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would likely remain undetectable against natural population fluctuations. Furthermore, it is not expected to significantly alter the background mortality rate.

Table 11.74: Kittiwake 35 Year Cumulative PVA Results for Collision Impacts Including Berwick Bank during the Pre-breeding Season

Scenario	Predicted Mortality (Original Impact) (no. of birds)	Growth Rate (Annual GR)	Median CPGR	Median CPS	U=50%I
NatureScot Approach – 0.993 avoidance rate	1,020.62	0.9918	0.9968	0.8906	42.92

When considering the impact during the breeding season on the regional population defined for the breeding season, using the NatureScot avoidance rates (0.993 avoidance) and with Berwick Bank included, the PVA predicted that the CPS was 0.626 ( Table 11.75 Open ▸ ). The median population size was therefore projected to be 37.38% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 21.76 In terms of the population size, this means that the median of the impacted population fell within the 21st percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was 0.987 ( Table 11.75 Open ▸ ) which translates to a median reduction of 1.29% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would likely remain undetectable against natural population fluctuations. Furthermore, it is not expected to significantly alter the background mortality rate.

Table 11.75: Kittiwake 35 Year Cumulative PVA Results for Collision Impacts Including Berwick Bank during the Breeding Season

Scenario	Predicted Mortality (Original Impact) (no. of birds)	Growth Rate (Annual GR)	Median CPGR	Median CPS	U=50%I
NatureScot Approach – 0.993 avoidance rate	1,514.44	0.9823	0.9871	0.6262	21.76

When considering the annual impact on the annual regional population, using the NatureScot avoidance rates (0.993 avoidance) and with Berwick Bank included, the PVA predicted that the CPS was 0.728 ( Table 11.76 Open ▸ ). The median population size was therefore projected to be 27.25% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 30.92. In terms of the population size, this means that the median of the impacted population fell within the 30th percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was 0.991 ( Table 11.76 Open ▸ ) which translates to a median reduction of 0.88% in population growth rate after 35 years. Such a decrease indicates that this level of impact would not adversely affect the population and would only result in a slight reduction in the growth rate currently seen in the BDMPS population and would therefore be undetectable against natural population fluctuations. Furthermore, it is not expected to significantly alter the background mortality rate.

Table 11.76: Kittiwake 35 Year Cumulative PVA Results for Displacement Impacts Including Berwick Bank on an Annual Basis

Scenario	Predicted Mortality (Original Impact) (no. of birds)	Growth Rate (Annual GR)	Median CPGR	Median CPS	U=50%I
NatureScot Approach – 0.993 avoidance rate	3,572.30	0.9863	0.9912	0.7275	30.92

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