5.5.3. Collision

  1. Operational wind turbines and associated infrastructure present a collision risk for seabirds flying within the array. Direct collision with infrastructure may result in injury or death; however, it is assumed that all collisions with operational wind turbines result in mortality.
  2. For the Array’s impacts, CRM for regularly occurring species was undertaken using the sCRM developed by Marine Scotland (McGregor et al., 2018). The User Guide for the sCRM Shiny App provided by Marine Scotland (Donovan, 2017) has been followed for the modelling of collision impacts predicted for the Array. The full methodology and input parameters is provided in volume 3, appendix 11.2 of the Array EIA Report.
  3. For other developments considered, the approach to quantifying collision risk is as detailed in the data sources listed in the tables below. This will not necessarily be identical to the approach undertaken by Ossian, given developments of new CRM software and/or changing evidence and advice regarding appropriate input parameters to use for modelling.

                        Operation and maintenance phase

                        Buchan Ness to Collieston Coast SPA
Kittiwake (seabird assemblage component only)
  1. The source information regarding kittiwake collision mortality from other relevant projects is given in Table 5.116   Open ▸ .

 

Table 5.116:
Kittiwake Collision Mortalities Apportioned to the Buchan Ness to Collieston Coast SPA from Other Relevant Projects

Table 5.116: Kittiwake Collision Mortalities Apportioned to the Buchan Ness to Collieston Coast SPA from Other Relevant Projects

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

 

  1. 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 5.117   Open ▸ .

 

Table 5.117:
Kittiwake Collision Mortalities Apportioned to the Buchan Ness to Collieston Coast SPA In-Combination Totals

Table 5.117: Kittiwake Collision Mortalities Apportioned to the Buchan Ness to Collieston Coast SPA In-Combination Totals

 

  1. With a population of 22,590 breeding adults (Burnell et al., 2023), 62,3 to 79.9 additional mortalities represents a 0.276 to 0.354 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.
  2. The PVA results are summarised in Table 5.118   Open ▸ . Full details are available in appendix 3B.

 

Table 5.118:
Summary of PVA Results for In-Combination Collision Impacts on Kittiwake at the Buchan Ness to Collieston Coast SPA

Table 5.118: Summary of PVA Results for In-Combination Collision Impacts on Kittiwake at the Buchan Ness to Collieston Coast SPA

 

  1. The kittiwake population of the Buchan Ness to Collieston Coast SPA has declined significantly between its citation level of 60,904 breeding adults and Seabird Census counts of 22,590 breeding adults (Burnell et al., 2023), and is assessed as being in “Unfavourable No Change” condition (NatureScot, ND). There have however been recent signs of slight recovery, with 13,547 AONs (27,094 individuals) recorded in 2023 (Tremlett et al, 2024).
  2. The PVA results show that the kittiwake population is expected to remain relatively stable under the counterfactual (no impact) scenario. Under the impacted scenarios, the CGR ranges is 0.996 under both the high and low approach if Berwick Bank Offshore Wind Farm’s impacts are included, or 0.997 if Berwick Bank Offshore Wind Farm’s impacts are excluded. This leads to a CPS after 35 years of 0.860 to 0.889 – i.e. the population size would be 11.1% to 14.0% smaller than the counterfactual population size.
  3. 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 kittiwake population, for all assessment scenarios and both with and without Berwick Bank Offshore Wind Farm.

                        Breeding Seabird Assemblage

  1. Of the components of the seabird assemblage, kittiwake was the only species for which a potential LSE2 was identified. As detailed above, it is expected that there would be a small but detectable negative impact on the kittiwake population. The seabird assemblage citation level is 95,000 individual seabirds, of which 60,904 were kittiwake. The decline in the kittiwake population between the citation level and Seabirds Count (Burnell et al., 2023) is therefore sufficient to adversely affect the overall population of the seabird assemblage. Whilst other components of the assemblage have increased in population, for example the guillemot population has increased from 17,280 breeding adults to 39,440 breeding adults (Burnell et al., 2023), this is unlikely to be sufficient to offset the decline in the kittiwake population. Therefore, 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.
  2. Therefore, it is concluded that there is a potential AEOI to the seabird assemblage feature of the Buchan Ness to Collieston Coast SPA as a result of the impact of collision from the Array in-combination with other developments.
                        East Caithness Cliffs SPA
Kittiwake
  1. The source information regarding kittiwake collision mortality from other relevant projects is given in Table 5.119   Open ▸ .

 

Table 5.119:
Kittiwake Collision Mortalities Apportioned to the East Caithness Cliffs SPA from Other Relevant Projects

Table 5.119: Kittiwake Collision Mortalities Apportioned to the East Caithness Cliffs SPA from Other Relevant Projects

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

 

  1. 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 5.120   Open ▸ .

 

Table 5.120:
Kittiwake Collision Mortalities Apportioned to the East Caithness Cliffs SPA In-Combination Totals

Table 5.120: Kittiwake Collision Mortalities Apportioned to the East Caithness Cliffs SPA In-Combination Totals

 

  1. With a population of 48,958 breeding adults (Burnell et al., 2023), 224.6 to 254.1 additional mortalities represents a 0.459 to 0.519 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.
  2. The PVA results are summarised in Table 5.121   Open ▸ . Full details are available in appendix 3B.

 

Table 5.121:
Summary of PVA Results for In-Combination Collision Impacts on Kittiwake at the East Caithness Cliffs SPA

Table 5.121: Summary of PVA Results for In-Combination Collision Impacts on Kittiwake at the East Caithness Cliffs SPA

 

  1. The kittiwake population of the East Caithness Cliffs SPA has declined slightly from its citation level of 65,000 breeding adults and recent counts of 48,958 breeding adults (Burnell et al., 2023), although it is assessed as being in “Favourable Maintained” condition (NatureScot, ND).
  2. The PVA results show that the kittiwake population is expected to remain relatively stable under the counterfactual (no impact) scenario. Under the impacted scenarios, the CGR is 0.994 under both the high and low approach if Berwick Bank Offshore Wind Farm’s impacts are included, or 0.994 to 0.995 if Berwick Bank Offshore Wind Farm’s impacts are excluded. This leads to a CPS after 35 years of 0.801 to 0.822 – i.e. the population size would be 17.8% to 19.9% smaller than the counterfactual population size.
  3. 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 East Caithness Cliffs SPA as a result of collision impacts from the Array in-combination with other developments.

                        Breeding Seabird Assemblage

  1. 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.
  2. Therefore, it is concluded that there is a potential AEOI to the seabird assemblage feature of the East Caithness Cliffs SPA as a result of the impact of collision from the Array in-combination with other developments.