The source information regarding gannet collision mortality from other relevant projects is given in Table 5.152 Open ▸ .

Project(s)	Data Source	Approach	Adult Mortalities
Project(s)	Data Source	Approach	Pre-Breeding Season	Breeding Season	Post-Breeding	Annual Total
UK North Sea projects	SSE Renewables (2022)	Scoping	N/A	N/A	N/A	N/A
UK North Sea projects	SSE Renewables (2022)	Developer	N/A	N/A	N/A	N/A
Green Volt Offshore Wind Farm	Green Volt Offshore Wind Farm (2023)	N/A	0.1	0.7	0.0	0.8
West of Orkney Wind Farm	Offshore Wind Power Limited (2023)	Low	0.0	0.0	0.5	0.6
West of Orkney Wind Farm	Offshore Wind Power Limited (2023)	Mid	0.0	0.0	0.8	0.8
West of Orkney Wind Farm	Offshore Wind Power Limited (2023)	High	0.0	0.0	1.0	1.0
Pentland Floating Offshore Wind	Xodus Group Ltd (2022)	N/A	N/A	0.2	N/A	0.2
Berwick Bank Offshore Wind Farm alone	SSE Renewables (2022)	Scoping	N/A	N/A	N/A	N/A
Berwick Bank Offshore Wind Farm alone	SSE Renewables (2022)	Developer	N/A	N/A	N/A	N/A

From this information, the various approaches have been consolidated into a “low” and a “high” estimate for the total in-combination impact. This is presented in Table 5.153 Open ▸ .

Project(s)	Adult Mortalities
	Pre-Breeding Season		Breeding Season		Post-Breeding Season		Annual Total
	Low	High	Low	High	Low	High	Low	High
UK North Sea projects	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
Green Volt Offshore Wind Farm	0.1	0.1	0.7	0.7	0.0	0.0	0.8	0.8
West of Orkney Wind Farm	0.0	0.0	0.0	0.0	0.5	1.0	0.6	1.0
Pentland Floating Offshore Wind	N/A	N/A	0.2	0.2	N/A	N/A	0.2	0.2
Berwick Bank Offshore Wind Farm	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
Ossian	0.0	0.0	0.7	1.2	0.1	0.2	0.8	1.4
Total	0.1	0.1	1.6	2.1	0.6	1.2	2.3	3.4

With a population of 120,580 breeding adults (Burnell et al., 2023), 2.3 to 3.4 additional mortalities represents a 0.002 to 0.003 percentage point increase in mortality rates. Therefore, it can be concluded, beyond reasonable scientific doubt, that there is no risk of an AEOI to the gannet feature of St Kilda SPA resulting from collision impacts from the Array in-combination with other developments.

Breeding Seabird Assemblage

Of the components of the seabird assemblage, gannet was the only species for which a potential LSE2 was identified for collision. As detailed above, there is expected to be no AEOI on the gannet feature. Therefore, it can also be concluded, beyond reasonable scientific doubt, that there is no AEOI to the seabird assemblage feature of the St Kilda SPA as a result of collision from the Array in combination with other developments.

The source information regarding kittiwake collision mortality from other relevant projects is given in Table 5.154 Open ▸ .

Project(s)	Data Source	Approach	Adult Mortalities
Project(s)	Data Source	Approach	Pre-Breeding Season	Breeding Season	Post-Breeding	Annual Total
UK North Sea projects	SSE Renewables (2022)	Scoping	29.9	9.4	22.7	62.0
UK North Sea projects	SSE Renewables (2022)	Developer	28.9	8.5	21.1	58.5
Green Volt Offshore Wind Farm	Green Volt Offshore Wind Farm (2023)	N/A	0.1	0.9	0.2	1.2
West of Orkney Wind Farm	Offshore Wind Power Limited (2023)	Low	1.2	0.5	0.9	2.6
West of Orkney Wind Farm	Offshore Wind Power Limited (2023)	Mid	1.3	0.6	1.0	2.8
West of Orkney Wind Farm	Offshore Wind Power Limited (2023)	High	1.4	0.6	1.1	3.1
Pentland Floating Offshore Wind	Xodus Group Ltd (2022)	N/A	0.0	0.0	0.0	0.0
SEP & DEP	Equinor (2022)	Developer	0.0	0.0	0.1	0.1
Outer Dowsing	Outer Dowsing Offshore Wind (2023)	Developer	N/A	N/A	N/A	1.8*
Berwick Bank Offshore Wind Farm alone	SSE Renewables (2022)	Scoping	5.3	2.7	3.9	11.9
Berwick Bank Offshore Wind Farm alone	SSE Renewables (2022)	Developer	4.3	1.9	2.3	8.5

*Apportioned impacts only presented on an annual basis in source document.

From this information, the various approaches have been consolidated into a “low” and a “high” estimate for the total in-combination impact. This is presented in Table 5.155 Open ▸ .

Project(s)	Adult Mortalities
	Pre-Breeding Season		Breeding Season		Post-Breeding Season		Annual Total
	Low	High	Low	High	Low	High	Low	High
UK North Sea projects	28.9	29.9	8.5	9.4	21.1	22.7	58.5	62.0
Green Volt Offshore Wind Farm	0.1	0.1	0.9	0.9	0.2	0.2	1.2	1.2
West of Orkney Wind Farm	1.2	1.4	0.5	0.6	0.9	1.1	2.6	3.1
Pentland Floating Offshore Wind	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
SEP & DEP	0.0	0.0	0.0	0.0	0.1	0.1	0.1	0.1
Outer Dowsing							1.8	1.8
Berwick Bank Offshore Wind Farm	4.3	5.3	1.9	2.7	2.3	3.9	8.5	11.9
Ossian	0.0	0.2	0.2	1.4	0.0	0.1	0.2	1.7
Total (Including Berwick Bank Offshore Wind Farm)	30.2	31.6	10.1	12.3	22.3	24.2	64.4	69.9
Total (Excluding Berwick Bank Offshore Wind Farm)	25.9	26.3	8.2	9.6	20.0	20.3	55.9	58.0

With a population of 21,232 breeding adults (Burnell et al., 2023), 55.9 to 69.9 additional mortalities represents a 0.263 to 0.329 percentage point increase in mortality rates. Therefore, PVA has been carried out both with and without Berwick Bank Offshore Wind Farm and for the high and low scenarios, to further assess the total in-combination impact.
The PVA results are summarised in Table 5.156 Open ▸ . Full details are available in appendix 3B.

Scenario	Approach	Adult Mortality	Citation Population (Breeding Adults)	Recent Population (Burnell et al., 2023) (Breeding Adults)	Median Unimpacted Population After 35 Years	Median Impacted Population After 35 Years	Median CGR	Median CPS
Including Berwick Bank Offshore Wind Farm	Low	64.4	63,200	21,232	20,017	17,608	0.996	0.879
Including Berwick Bank Offshore Wind Farm	High	69.9				17,419	0.996	0.869
Excluding Berwick Bank Offshore Wind Farm	Low	55.9				17,892	0.997	0.894
Excluding Berwick Bank Offshore Wind Farm	High	58.0				17,833	0.997	0.890

The kittiwake population of the Troup, Pennan and Lion’s Head SPA has decreased between its citation level of 63,200 breeding adults and recent counts of 21,232 breeding adults (Burnell et al., 2023).
The median CGR is 0.996 to 0.997 which indicates the population growth rate declines by 0.3% to 0.4% compared to the counterfactual. After 35 years (the expected lifespan of the Array), the CPS ranges from 0.869 to 0.894. Whilst this level of impact is small, it is not negligible and in the context of a population that is already declining, the additional mortality from the Array in combination with other projects and plans would appear to have the potential to adversely affect the likelihood of the site meeting its conservation objectives for all assessment scenarios and both with and without Berwick Bank Offshore Wind Farm.
Therefore, it is concluded that there is a potential AEOI to the kittiwake feature of the Troup, Pennan and Lion’s Head SPA as a result of collision impacts from the Array in-combination with other developments.

Breeding Seabird Assemblage

Of the components of the seabird assemblage, kittiwake was the only species for which a potential LSE2 was identified for collision risk. As detailed above, there is expected to be a significant impact on the kittiwake population. The kittiwake population at citation was significantly higher than the current population (Burnell et al., 2023). Whilst the magnitude of the impact would not be deemed sufficient to risk entirely losing kittiwake as a viable component of the assemblage, the decline is sufficient to adversely affect the total population size of the overall assemblage.
Therefore, it is concluded that there is a potential AEOI to the seabird assemblage feature of the Troup, Pennan and Lion’s Head SPA as a result of the impact of collision from the Array in-combination with other developments.

Tables ▼