11.8. Key Parameters for Assessment

11.8.1. Maximum Design Scenario

  1. The Maximum Design Scenarios (MDSs) identified in Table 11.11   Open ▸ are those expected to have the potential to result in the greatest effect on an identified VOR. These scenarios have been selected from the details provided in volume 1, chapter 3 of the Array EIA Report. Effects of greater adverse significance are not predicted to arise should any other development scenario, based on details within the Project Description (volume 1, chapter 3) (e.g. different infrastructure layout) be taken forward in the final design scheme.

.

Table 11.11:
Maximum Design Scenario Considered for Each Potential Impact on Offshore Ornithology

Table 11.11: Maximum Design Scenario Considered for Each Potential Impact on Offshore Ornithology

 

11.8.2. Species Assessed for Each Impact

  1. Table 11.12   Open ▸ sets out the VORs that are considered for each impact being assessed, alongside an explanatory justification when species are ruled out for a particular impact.

 

Table 11.12:
Species Assessed for Each Impact

Table 11.12: Species Assessed for Each Impact

 

11.8.3. Impacts Scoped Out of the Assessment

  1. The offshore ornithology pre-Scoping workshop (see Table 11.3   Open ▸ ) was used to facilitate stakeholder engagement on topics to be scoped out of the assessment.
  2. On the basis of the baseline environment and the Project Description outlined in volume 1, chapter 3 of the Array EIA Report, a number of impacts are proposed to be scoped out of the assessment for offshore ornithology. This was either agreed with key stakeholders through consultation as discussed in volume 1, chapter 5, or otherwise, the impact was proposed to be scoped out in the Array EIA Scoping Report (Ossian OWFL, 2023) and no concerns were raised by key consultees within the Ossian Array Scoping Opinion (MD-LOT, 2023).
  3. These impacts are outlined, together with justification for scoping them out, in Table 11.13   Open ▸ .

 

Table 11.13:
Impacts Scoped Out of the Assessment for Offshore Ornithology (Tick Confirms the Impact is Scoped Out)

Table 11.13: Impacts Scoped Out of the Assessment for Offshore Ornithology (Tick Confirms the Impact is Scoped Out)

11.9. Methodology for Assessment of Effects

11.9.1. Overview

  1. The offshore ornithology assessment of effects has followed the methodology set out in volume 1, chapter 6 of the Array EIA Report. Specific to the offshore ornithology EIA, the following guidance documents have also been considered:
  • NatureScot Marine Ornithology Guidance Notes to support Offshore Wind Applications (NatureScot, 2023a-k):

-        Guidance Note 1: Guidance to support Offshore Wind Applications: Marine Ornithology – Overview (NatureScot, 2023a);

-        Guidance Note 2: Guidance to support Offshore Wind Applications: Advice for Marine Ornithology Baseline Characterisation Surveys and Reporting (NatureScot, 2023b);

-        Guidance Note 3: Guidance to support Offshore Wind applications: Marine Birds – Identifying theoretical connectivity with breeding site Special Protection Areas using breeding season foraging ranges (NatureScot, 2023c);

-        Guidance Note 4: Guidance to Support Offshore Wind Applications: Ornithology – Determining Connectivity of Marine Birds with Marine Special Protection Areas and Breeding Seabirds from Colony SPAs in the Non Breeding Season (NatureScot, 2023d);

-        Guidance Note 5: Guidance to support Offshore Wind Applications: Recommendations for marine bird population estimates (NatureScot, 2023e);

-        Guidance Note 6: Guidance to support Offshore Wind Applications – Marine Ornithology Impact Pathways for Offshore Wind Developments (NatureScot, 2023f);

-        Guidance Note 7: Guidance to support Offshore Wind Applications: Marine Ornithology – Advice for assessing collision risk of marine birds (NatureScot, 2023g);

-        Guidance Note 8: Guidance to support Offshore Wind applications: Marine Ornithology Advice for assessing the distributional responses, displacement and barrier effects of Marine birds (NatureScot, 2023h);

-        Guidance Note 9: Guidance to support Offshore Wind applications: Marine Ornithology Advice for Seasonal Definitions for Birds in the Scottish Marine Environment (NatureScot, 2023i);

-        Guidance Note 10: Guidance to support Offshore Wind applications: Marine Ornithology Advice for apportioning impacts to breeding colonies (NatureScot, 2023j); and

-        Guidance Note 11: Guidance to support Offshore Wind Applications: Marine Ornithology – Recommendations for Seabird Population Viability Analysis (PVA) (NatureScot, 2023k).

  • Incorporating data uncertainty when estimating potential vulnerability of Scottish seabirds to marine renewable energy developments (Wade et al., 2016);
  • Assessing vulnerability of marine bird populations to offshore wind farms (Furness et al., 2013);
  • Scaling possible adverse effects of marine wind farms on seabirds: developing and applying a vulnerability index (Garthe and Hüppop, 2004);
  • Joint SNCB Interim Displacement Advice Note: Advice on how to present assessment information on the extent and potential consequences of seabird displacement from Offshore Wind Farm developments (JNCC, 2022);
  • Modelling flight heights of marine birds to more accurately assess collision risk with offshore wind turbines (Johnston et al., 2014);
  • Using a Collision Risk Model to Assess Bird Collision Risks for Offshore Wind Farms (Band, 2012);
  • A Stochastic Collision Risk Model for Seabirds in Flight (McGregor et al., 2018);
  • Guidelines for Ecological Impact Assessment in the UK and Ireland (CIEEM, 2022); and
  • Developing Guidance on Ornithological Cumulative Impact Assessment for Offshore Wind Farm Developers (King et al., 2009).
  1. The methodology has also considered the needs of the relevant policy and legislation, as described in volume 1, chapter 2 of this Array EIA Report, and Table 11.1   Open ▸ and Table 11.2   Open ▸ within this chapter.

11.9.2. Criteria for Assessment of Effects

  1. When determining the significance of effects, a two stage process is used which involves defining the magnitude of the potential impacts and the sensitivity of the receptors. This section describes the criteria applied in this chapter to assign values to the magnitude of potential impacts and the sensitivity of the receptors. The terms used to define magnitude and sensitivity are based on those which are described in further detail in volume 1, chapter 6 of the Array EIA Report.
  2. The criteria for defining magnitude in this chapter are outlined in Table 11.14   Open ▸ . Each assessment considers the spatial extent, duration, frequency and reversibility of impact when determining magnitude, and these are outlined within the magnitude section of each impact assessment (e.g. a duration of hours or days would be considered for most receptors to be of short-term duration, which is likely to result in a low magnitude of impact). The definitions have been adapted to be suitable for offshore ornithology, following the approach and guidance set out by CIEEM (2022).
  3. To aid with categorising the magnitude of impact, a 1% threshold in increase in baseline mortality was utilised, with the level of impact from the offshore wind farm divided by the baseline mortality estimate. Generally, based on findings from population viability analyses for bird species, it would be considered that increases in mortality rates of less than 1% would be undetectable in terms of changes in population size, whereas increases above 1% may produce detectable effects (Natural England, 2022). Note that NatureScot (2023k) guidance states that a 0.02 percentage point change in survival rate is to be used when assessing the impact to SPA populations. As the EIA deals with larger combined populations (that include non-SPA colonies) and not individual SPA populations, the 1% was deemed as the most appropriate approach for the EIA. A 0.02 percentage point change in survival rate threshold has been used within the Array RIAA (Ossian OWFL, 2024).
Table 11.14:
Definition of Terms Relating to the Magnitude of an Impact

Table 11.14: Definition of Terms Relating to the Magnitude of an Impact

 

  1. Further information on levels of population importance and conservation value are given in volume 3, appendix 11.1. Criteria used to determine potential for recovery are given in Table 11.15   Open ▸ .

 

Table 11.15:
Definition of Potential for Recovery

Table 11.15: Definition of Potential for Recovery

 

  1. The criteria for defining sensitivity in this chapter are outlined in Table 11.16   Open ▸ . The definitions have been adapted to be suitable for offshore ornithology, following the approach and guidance set out by CIEEM (2022). The conservation value of ornithological receptors is based on the population from which individuals are predicted to be drawn. This reflects current understanding of the movements of species, with site-based protection (e.g. SPAs) generally limited to specific periods of the year (e.g. the breeding season). Therefore, conservation value can vary through the year depending on the relative sizes of the number of individuals predicted to be at risk of impact and the population from which they are estimated to be drawn. Conservation value therefore corresponds to the degree of connectivity which is predicted between the offshore wind farm site and protected populations.

 

Table 11.16:
Definition of Terms Relating to the Sensitivity of the Receptor

Table 11.16: Definition of Terms Relating to the Sensitivity of the Receptor

 

  1. The magnitude of the impact and the sensitivity of the receptor are combined when determining the significance of the effect upon offshore ornithology VORs. The particular method employed for this assessment is presented in Table 11.17   Open ▸ .
  2. Where a range is suggested for the significance of effect, for example, minor to moderate, it is possible that this may span the significance threshold. The technical specialist’s professional judgement will be applied to determine which outcome defines the most likely effect, whilst taking into account the sensitivity of the receptor and the magnitude of impact. Where professional judgement is applied to quantify final significance from a range, the assessment will set out the factors that result in the final assessment of significance. These factors may include the likelihood that an effect will occur, data certainty and relevant information about the wider environmental context.
  3. For the purposes of this assessment:
  • A level of residual effect of moderate or more will be considered a ‘significant’ effect in terms of the EIA Regulations; and
  • A level of residual effect of minor or less will be considered ‘not significant’ in terms of the EIA Regulations.
  1. Effects of moderate significance or above are therefore considered important in the decision-making process, whilst effects of minor significance or less warrant little, if any, weight in the decision-making process.
Table 11.17:
Matrix Used for the Assessment of the Significance of the Effect

Table 11.17: Matrix Used for the Assessment of the Significance of the Effect

 

11.9.3. Designated Sites

  1. This offshore ornithology Array EIA Report chapter assesses the LSE1 in EIA terms on the qualifying interest feature(s) of Natura 2000 sites (i.e. nature conservation sites in Europe designated under the Habitats or Birds Directives[11]) and sites in the UK that comprise the National Site Network (collectively termed ‘European sites’) as described within section 11.7.2 of this chapter. The Array RIAA (Ossian OWFL, 2024) includes the assessment of the potential impacts on the features of each protected site individually in terms of the Habitats Regulations (Ossian OWFL, 2024).
  2. Where locally designated sites and national designations (other than European sites) fall within the boundaries of a European site (e.g. SSSIs which have not been assessed within the Array RIAA) and where qualifying interest features are the same, only the European site has been taken forward for assessment. Potential impacts on the integrity and conservation status of the offshore ornithology features of a locally or nationally designated site are assumed to be inherent within the assessment of the European site, so a separate assessment for the local or national site has not been undertaken.
  3. However, assessment of the LSE1 on a local or nationally designated site which falls outside the boundaries of a European site, but within the offshore ornithology study area, has been considered within this chapter. Given ornithological features are highly mobile, birds within the Array’s ZoI (as defined in section 11.3) may by associated with designated sites over a wide area, or they may not be associated with a designated site. An individual bird may be associated with different designated sites at different times of year or across different years. Therefore, unless there is evidence to the contrary, it is assumed that the impact on a designated site is proportional to the impact of the Array on the wider regional population containing that designated site. Such evidence may include tracking data or similar indicating disproportionately high levels of connectivity between a site and the Array. While impacts have been apportioned to non-European sites, these have not been assessed in any great detail as it is not the standard approach to do so. It is assumed the overall EIA-level effect conclusion is also applicable to any such designated site.