PVA Assessment Including Berwick Bank

When considering the impact during the breeding season on the regional population defined for the breeding season, using the NatureScot avoidance rates (0.994 avoidance) and with Berwick Bank included, the PVA predicted that the CPS was 0.815 ( Table 11.82 Open ▸ ). The median population size was therefore projected to be 18.34% smaller than the unimpacted population over a 35 year time period, with a 50th centile value of 33.32. In terms of the population size, this means that the median of the impacted population fell within the 33rd percentile of the unimpacted population (a value of 50 would indicate that they are the same). This suggests that the impacted scenario was still within the margin of error of the non-impacted scenario, and therefore there would likely be no adverse effect to the population. However, as stated, the CPGR is considered a more robust metric compared to the CPS in this analysis due to the models being conducted with density independence, in line with NatureScot (2023k) guidance. The PVA model predicted that the CPGR was 0.994 ( Table 11.82 Open ▸ ) which translates to a median reduction of 0.57% 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 11.82: Herring gull 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 - 0.994 avoidance rate	64.4	0.9443	0.9943	0.8153	33.32

Magnitude of impact

The estimated mortality resulting from collision during operation and maintenance was assessed for each season, and also on an annual basis by combining seasonal impacts and comparing them against the largest regional seasonal population (as set out in volume 3, appendix 11.2).
Based on the PVA results for the breeding season with Berwick Bank included and following the NatureScot Approach using a 0.994 avoidance rate, the impact from the cumulative assessment on the herring gull population was perceived as low.
Based on the collision assessment, with Berwick Bank included and following the NatureScot Approach using a 0.994 avoidance rate, for the non-breeding season the magnitude of impact on the herring gull population is considered to be of low magnitude
Based on the collision assessment, with Berwick Bank included and following the NatureScot Approach using a 0.994 avoidance rate, on an annual basis the magnitude of impact on the herring gull population is considered to be of low magnitude
Based on the collision assessment results for the breeding season with Berwick Bank excluded and following the NatureScot Approach using a 0.994 avoidance rate, the impact from the cumulative assessment on the herring gull population was perceived as low.
Based on the collision assessment, with Berwick Bank excluded and following the NatureScot Approach using a 0.994 avoidance rate, for the non-breeding season the magnitude of impact on the herring gull population is considered to be of low magnitude
Based on the collision assessment, with Berwick Bank excluded and following the NatureScot Approach using a 0.994 avoidance rate, on an annual basis the magnitude of impact on the herring gull population is considered to be of low magnitude
Herring gull populations have been declining within the UK with Burnell et al. (2023) reporting that the population has decreased by around 30%, with colonies within Scotland down 44% (NatureScot, 2024). However it is evident that this decline is attributed to the presence of other pressures such as food availability, bycatch, disease and pollution (Gorski et al. 1977; Zydelis et al. 2013). The PVA indicates that cumulative mortality attributed to offshore wind farms would have a minimal impact on the overall population trajectory.
Due to the minimal level of change to baseline conditions, the cumulative effect is predicted to be of national spatial extent, long-term duration, continuous and high reversibility. It is predicted that the impact will affect the receptor directly. The magnitude is therefore, considered to be low.

Sensitivity of the receptor

Herring gull was rated as one of the most vulnerable seabird species to collision impacts by Wade et al. (2016), due to the proportion of flights likely to occur at potential risk height and percentage of time in flight. In terms of nocturnal activity rate, herring gull are considered to have a medium rate of activity at night with a score of three (out of five) (Wade et al. 2016).
As herring gull is a qualifying interest for two SPAs likely to be connected to the Array (within the mean-max + SD foraging range of Fowlsheugh SPA and Buchan Ness to Collieston Coast SPA) with multiple non-SPA colonies within range, the species is considered to be of international value. Refer to Table 6.7 of volume 3, appendix 11.1 for details of SPAs with connectivity to the Array with regards to herring gull.
Herring gull lay up to three eggs and breed from the age of four onwards, typically living on average for 12 years (Burnell et al., 2023). Natural nesting colonies of herring gull have undergone decreases of approximately 44% in Scotland since the early 2000s, whereas urban-nesting populations have increased considerably. Given that the urban population is small compared to the natural population (Burnell et al., 2023), the overall trend is likely to be a decline. Surveys managed by the RSPB in 2023 have recorded indicative declines of 7% across a number of sites in Britain in 2023 when compared against a pre-HPAI baseline (Tremlett et al., 2024). Overall herring gull is considered to have low recoverability.
Herring gull is deemed to be of very high vulnerability, low recoverability and international value. The sensitivity of the receptor is therefore, considered to be high.

Significance of the effect

Overall, the magnitude of the impact is deemed to be low and the sensitivity of the receptor is considered to be high. The effect will, therefore, be of minor to moderate adverse significance. However, considering the non-breeding season and annual mortality rates are below 1% of baseline mortality, along with the PVA results indicating a low impact with and without Berwick Bank, the effect should be considered minor. It is therefore deemed appropriate to categorise the impact as having a minor adverse significance, which is not significant in EIA terms.

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.

Gannet

The estimated collision mortalities of gannet for the purpose of estimating cumulative collisions impacts are given in Table 11.83 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 11.83: Gannet Cumulative Collision Mortalities

Project		Season
Project	Avoidance Rate used in Assessment	Breeding	Post-breeding	Pre-breeding
Aberdeen	98.9%	3.48	4.22	0.08
Beatrice	98.9%	37.4	48.8	9.5
Blyth Demo Phase 1	98.9%	3.5	2.1	2.8
Blyth Demo Phase 2 and 3	unknown	-	-	-
Dogger Bank A and B	98.9%	81.1	83.5	54.4
Dogger C and Sofia	98.9%	14.8	10.1	10.8
Dudgeon	98.9%	22.3	38.9	19.1
Dudgeon Extension and Sheringham Shoal Extension	99.2%	0.4	0.6	0
East Anglia ONE	98.9%	3.4	131	6.3
East Anglia ONE North	98.9%	12.4	11	1.1
East Anglia THREE	98.9%	4.8	28.5	8.4
East Anglia TWO	98.9%	12.5	23.1	4
Five Estuaries	99.3%	2.01	1.14	0.61
Forthwind Demonstration Project	unknown	-	-	-
Galloper	98.9%	N/A (outside foraging range)	30.9	12.6
Gunfleet Sands 3 Demonstration Project	unknown	-	-	-
Green Volt Offshore Wind Farm	99.3%	14.9	0.6	2.4
Hornsea Project One	98.9%	2.61	7.27	5.11
Hornsea Project Two	98.9%	7	14	6
Hornsea Project Three	98.9%	9.77	4.51	4.93
Hornsea Project Four	98.9%	15.8	5.2	1.3
Humber Gateway	98.9%	1.9	1.1	1.5
Hywind	98.9%	5.6	0.8	0.8
Inch Cape Offshore Wind Farm	98.9%	108	5	4
Kentish Flats	98.9%	N/A (outside foraging range)	0.8	1.1
Kentish Flats Extension	unknown	N/A (outside foraging range)	-	-
Kincardine Offshore Wind Farm	98.9%	3	0	0
Lincs	98.9%	2.1	1.3	1.7
London Array	98.9%	N/A (outside foraging range)	1.4	1.8
Moray East	98.9%	80.6	35.4	8.9
Moray West	98.9%	9.8	1.5	0.7
Neart na Gaoithe	98.9%	89	7	7
Norfolk Boreas	98.9%	14.1	12.7	3.9
North Falls (PEIR)	98.9%	6.5	8.1	4.7
Norfolk Vanguard	98.9%	8.2	18.6	5.3
Outer Dowsing	99.3%	1.05	0.36	0.07
Pentland Floating Offshore Wind	98.9%	N/A (outside foraging range)	0	0
Race Bank	98.9%	33.7	11.7	4.1
Rampion 1	98.9%	N/A (outside foraging range)	13.9	0.5
Rampion 2	99.3%	N/A (outside foraging range)	1.4	0.61
Seagreen 1 and 1A Offshore Wind Farm	98.9%	159	8	9
Sheringham Shoal	unknown	14.1	3.5	0
Teesside	98.9%	4.9	1.7	0
Thanet	98.9%	N/A (outside foraging range)	0	0
Triton Knoll	98.9%	26.8	64.1	30.1
West of Orkney	99.3%	37.78	7.65	2.05
Westermost Rough	98.9%	N/A	N/A	N/A
Total	-	854.3	651.45	237.26
Berwick Bank	98.9%	170	18	3
Ossian	99.3%	28.18	3.76	0.24
Total (including Berwick Bank)	-	1052.48	673.21	240.5
Total (excluding Berwick Bank)	-	882.48	655.21	237.5

The cumulative collision mortality is given in Table 11.84 Open ▸ (with Berwick Bank included) and Table 11.85 Open ▸ (with Berwick Bank excluded).

Table 11.84: Gannet 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	248,385	47,864	240.5	0.502
Breeding	763,577	147,141	673.21	0.458
Post-breeding	456,298	87,929	1052.48	1.197
Annual	763,577	147,141	1,966.19	1.336

With Berwick Bank, the estimated collision mortality for gannet is 241 individuals in the pre-breeding season, 673 individuals in the breeding season and 1,052 in the post-breeding season. This is equivalent to an increase in baseline mortality of 0.50% in the pre-breeding season, 0.46% in the breeding season and 1.20% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 1,966, which equates to an increase in baseline mortality of 1.34% ( Table 11.84 Open ▸ ).

Table 11.85: Gannet 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	248,385	47,864	237.09	0.485
Breeding	763,577	147,141	882.48	0.592
Post-breeding	456,298	87,929	655.21	0.745
Annual	763,577	147,141	1,774.78	1.206

Without Berwick Bank, the estimated collision mortality for gannet is 237 individuals in the pre-breeding season, 882 individuals in the breeding season and 655 in the post-breeding season. This is equivalent to an increase in baseline mortality of 0.49% in the pre-breeding season, 0.59% in the breeding season and 0.75% in the post-breeding season. On an annual basis, the number of mortalities is estimated as 1,775 individuals, which equates to an increase in baseline mortality of 1.20% ( Table 11.85 Open ▸ ).
The cumulative collision mortality therefore represents an increase in annual mortality of over 1% of baseline mortality, both with Berwick Bank included for the post-breeding season and on an annual basis. With Berwick Bank excluded, the 1% threshold is surpassed on an annual basis only. Therefore, to further assess the significance of this effect, a PVA has been carried out for gannet as described in volume 3, appendix 11.5.

Previous part

Next part

Tables ▼