1. Introduction

1. Berwick Bank Wind Farm Limited (BBWFL) is a wholly owned subsidiary of SSE Renewables Limited and will hereafter be referred to as ‘the Applicant’. The Applicant is developing the Berwick Bank Wind Farm (hereafter referred to as ‘the Project’) located in the outer Forth and Tay region (Figure 1.1).
2. The Proposed Development is located adjacent to the consented Firth of Forth offshore wind farms consisting of Seagreen to the north, Inch Cape to the northwest and Neart na Gaoithe to the west (Figure 1.1). 
3. The proposed Berwick Bank development will, if consented, provide an estimated 4.1 GW of renewable energy, making it one of the largest offshore wind farms in the world. Given the anticipated operational life span of 35 years, the Project will make a critical contribution to Scotland’s renewable energy target of 11 GW of new offshore wind by 2030.  

Figure 1.1: Site boundaries for all consented and proposed wind farms currently within the Outer Firth of Forth.

2. Purpose of the report

4. This Technical Report describes the seasonal apportioning of seabirds at the Proposed Development area to non-designated colonies and Special Protection Areas (SPAs) to inform the Environmental Impact Assessment Report (EIAR) and Habitats Regulation Appraisal (HRA) for the Proposed Development.
5. Apportioning provides a means of estimating the proportions of birds present within the impacted area that derive from different colony populations. Consequently, the results from apportioning allow the impacts of the Proposed Development to be allocated across each of the relevant SPA populations. Potential impacts from collision and displacement/barrier effects are presented in the Ornithology Technical Appendices 11.3 and 11.4, respectively, and the apportioned population-level impacts by age class in the Technical Appendix 11.6: Population Viability Analysis. 
6. The apportioning of breeding season birds has been undertaken for all species listed in Section 3.1, except kittiwake, guillemot and razorbill, using a “theoretical approach” presented in NatureScot’s interim guidance note (NatureScot, 2018) and implemented using R software (R version 4.0.5 (2021-03-31)). This method was advised by NatureScot and Marine Scotland Science (MSS) through their Scoping representations and advice (4th February 2022). The method provides an apportioning “weighting” to each of the breeding colonies within the mean maximum foraging range plus one standard deviation (SD) (Woodward et al., 2019) of the Proposed Development Array area.
7. Marine Scotland’s Apportioning Tool (Butler et al., 2020) was used for breeding season apportionment of guillemot, razorbill and kittiwake, as advised by MSS in their Scoping representation and advice (4th February 2022). The method used is based on statistical models of GPS data for birds tracked from their breeding colonies (Wakefield et al., 2017; 2019).
8. In the non-breeding season, the information from Furness (2015) on Biologically Defined Minimum Population Scales (BDMPS) was used for all species to apportion birds, except guillemot and herring gull.  The methodology for gannet took account of revised information on seasonal movements (McArthur Green, 2015).
9. For guillemot, non-breeding season estimates were apportioned based on breeding season regional populations using the approach outlined in the NatureScot interim guidance, advised by MSS (24th August 2021) and confirmed by NatureScot based on the analyses of geolocator data presented in Buckingham et al. (2022).
10. For herring gull, apportioning for the non-breeding season was also carried out using the breeding season NatureScot approach but with a correction applied to the regional breeding numbers, to account for the influx of non-UK and west coast UK birds into the North Sea BDMPS. This approach was confirmed through the Ornithology Roadmap Process (RM6; Appendix 11.8).
11. In the case of puffin, no apportionment of impacts was required for the non-breeding season because this species leaves UK colonies and the immediately adjacent sea area by late August and disperses widely over vast areas (Furness, 2015).
12. Apportionment of Arctic tern estimates of collisions has also not been undertaken. The Arctic tern is a designated species of the Forth Islands SPA which comprises seabird colonies on Inchmickey, Isle of May, Fidra, The Lamb, Craigleith and Bass Rock. Of these islands, Artic terns are only present on the Isle of May; the closest distance between the Development Array area and the Isle of May colony is 40.9 km, which is only just within the breeding season foraging range (40.5 km, see Table 3.2; the mean max foraging range + 1 SD from Woodward et al., 2019) of the Isle of May colony. The Applicant concludes that the Development Array area has little, if any, connectivity to the SPA population.

3. Methods

3.1. Species and relevant colonies

13. Apportioning was undertaken for the species outlined in Table 3.1.

Table 3.1: Species and Impacts for which Apportioning was Undertaken.

14. These species are protected as features of breeding colony SPAs. The SPA and non-SPA colonies to which birds have been apportioned are those within species-specific breeding season foraging ranges from the Development Array area, defined as the mean max foraging range + 1 SD from Woodward et al. (2019) (Table 3.2), as advised by NatureScot in their scoping advice (7th December 2021).
15. The HRA Screening Report identified a long list of SPAs within breeding season foraging range of the Proposed Development Array area. This list was used to ensure that all relevant breeding season SPAs were considered in the apportioning process using both NatureScot (2018) and MSS Tool (Butler et al., 2020) methods (Table 3.3). A small number of SPA populations were screened in but were beyond the mean max foraging range +1 SD from the Development Array area on the basis of distance measurements undertaken for the apportioning. This was due to differences in how distances between the colonies and the Proposed Development Array area were measured; connectivity for HRA screening was determined using the closest points of the Array area (prior to the boundary revision) and the relevant SPA, whereas apportioning used the centre of the Array area to the closest point of the relevant SPA and “at-sea” distance.
16. The full suite of SPAs considered for apportioning are shown in Table 3.3.
17. The colony counts for each of the SPAs were provided from JNCC as two validated datasheets of all colony count data for the UK and Ireland within the Seabird Monitoring Programme (SMP) database for 1998 – 2019 and 1998-2021 to HiDef on 10th January 2022. For the species of interest here, the database summarised counts by subsites and whole SPAs; “counts” are recorded as individuals or Apparently Occupied Nests (AON) or Apparently Occupied Sites (AOS). For guillemot and razorbill, counts of individuals were converted to estimates of the population size by multiplying by the correction factor 1.34. Where counts were provided as AON/AOS, these were treated as equivalent to pairs and therefore doubled to arrive at a number of individuals and then multiplied by the correction factor of 1.34, which is an Isle of May specific correction factor but which has been applied in previous applications to guillemot and razorbill. Ideally, counts should be concurrent across breeding colonies of interest. However, for many SPAs, counts are divided by subsite and not all subsites are censused every year. Entire counts for SPAs comprising multiple subsites are often only achieved over a period of years.
18. For kittiwake, lesser black-backed gull, razorbill and gannet any additional colonies which occur within the BDMPS were advised to be screened in by NatureScot and MSS in their scoping advice (16th December 2021). The relevant colonies are reported in Section 4.3.

Table 3.2: Species and Foraging Ranges as per Woodward et al. (2019).

Table 3.3: SPA Colonies (Feature or Assemblage) Identified for Apportioning based on Breeding Season Foraging Range, where Distance to SPA has been Measured from the Centre of the Development Array Area to the Closest Point of the SPA Boundary *SPAs Beyond Foraging Range but Screened In[1]. Non-Designated Colonies Within Foraging Range are presented in Annex A.

3.2. Definitions of seasons

19. Through the Ornithology Road Map Process (RM1: Technical Appendix 11.8), advice was provided to define breeding and non-breeding seasons using the definitions in NatureScot (2020).
20. This was the basis for bio-seasons used within this technical report and summarised in Table 3.4.

• Breeding season: birds are strongly associated with a nest site, including nesting, egg-laying and provisioning young; and

• Non-breeding season: birds are more widely dispersed and no longer strongly associated with colonies. This period subsumes the short “pre-breeding” seasons defined separately in NatureScot (2020).
  21. Non-breeding season apportioning is reliant on information within BDMPS (Furness, 2015). For kittiwake, gannet and razorbill, Furness (2015) identifies autumn and spring passage and winter periods within the non-breeding season and therefore apportioning weightings were derived for these periods. The weightings from the apportioning were applied to mortality estimates for these species in Furness (2015) seasons which were foreshortened where they overlapped with the NatureScot breeding season definitions to avoid overestimating seasonal mortality estimates (Table 3.4).

Table 3.4: Bio-Seasons for Each Species Based on i) NatureScot (2020) in the Breeding Season for All Species and ii) NatureScot (2020) Used for All Species in the Non-Breeding Season Except for Kittiwake, Razorbill and Gannet which Were Adapted from Furness (2015). Apportioning Was Carried Out for All Species in Both Bio-Seasons, Except for Puffin (Breeding Season Only).

3.3. Apportioning methods

22. The weightings derived from the apportioning were used to assign seasonal estimates of mortality for each species by age class to seabird colonies. The mortality estimates are reported in Technical Appendices 11.3 and 11.4 concerning ornithology collision risk modelling and displacement. Impacts were estimated for the Developer Approach and Scoping Approaches, the latter segregated into two (a and b) based on advised mortality and displacement rates. Apportioning was carried out using the mortality estimates for each of these approaches.

Breeding season

NatureScot apportioning method

23. The apportioning calculation as advised in NatureScot (2018) is a weighting based on colony population size (adult individuals) of those within foraging range, distance between the centre of the Development Array area and the nearest boundary of the relevant breeding colonies within foraging range (see below), and area of sea encompassed by the foraging range. These three weighting factors are combined to obtain a proportional weight for each colony:

24. This apportioning calculation has been coded by HiDef Aerial Surveying Ltd. (“HiDef”) into the R programming language and a copy of the code can be provided upon request.
25. The seabird population estimates at the relevant SPAs used in the calculation are summarised in Table 3.3 and were obtained from the Seabird Monitoring Programme (SMP) database: JNCC provided two validated datasheets of all colony count data for the UK and Ireland within the SMP for 1998 – 2019 and 1998-2021 to HiDef on 10th January 2022. NatureScot (2018) advise that counts must be concurrent across breeding colonies of interest; if there is a significant temporal gap between the counts at different sites then an earlier baseline should be used to ensure counts of comparable age across the sites. However, for many SPAs, counts are divided by subsite and not all subsites are censused every year. Entire counts for SPAs comprising multiple subsites are often achieved over a period of years (see ‘Year of count’ Table 3.3). The most recent counts available were used in all cases. Relevant non-designated colonies are presented in Annex A.
26. The distance of the colony was measured as the distance between the geometric centre of the Windfarm Array to the closest point on the boundary of the colony, as per approach taken in Seagreen Optimised Addendum (2019). This was a compromise between options within the NatureScot guidance (2018) advocating a centroid-to-centroid approach and an approach that uses shortest distance between site and colony boundaries. To be biologically meaningful, these are the ‘at sea’ distances, rather than straight-line i.e., the actual shortest distance the bird flies across water between the breeding site and the Proposed Development.

Marine Scotland Science (MSS) apportioning method  

27. The method available in the MS Apportioning Tool (Butler et al,. 2020) derives apportioning percentages using a statistical model that incorporates spatial distributions of seabirds using tracking data and model parameters related to accessibility, competition, and environmental effects (Wakefield et al., 2017; 2019). The dependency on the modelled density layers of Wakefield et al. (2017; 2019) means that, amongst the species of concern for this Project, this method can only be used for kittiwake, guillemot and razorbill.
28. This method differs from the NatureScot approach by accounting for environmental heterogeneity and drivers of species distributions and allowing segregation of foraging ranges between colonies. Both may impact where birds from a certain colony are most likely to be found. It also empirically estimates colony-specific bird density at a certain location from the tracking data, rather than using a pre-defined, uniform density-distance decay that is identical for all species/colonies, as is assumed in the NatureScot approach. This approach is considered more biologically meaningful.
29. The MS method uses population counts from the Seabird 2000 census to derive the relative weightings on which the apportionment is based.
30. HiDef identified several issues with the use of the MS Tool, and these were discussed at the Marine Scotland Ornithology Impact Assessment Workshop (14 February 2022). One of the issues concerned how the tool measured distances between colonies and developments. The application of the MSS method within the Tool assigns weightings to SPAs that are beyond the breeding season foraging range as defined by the mean max distance + 1 SD from Woodward et al. (2019) due to the way in which the method defines “foraging range”. The MSS method within the Apportioning Tool uses the maximum observed foraging range from GPS data and adds a 10% buffer to account for potentially unobserved foraging trips. For any given species, the list of colonies that result from the use of the tool therefore differs from that which would be obtained via the application of the NatureScot approach. This results in a weighting assigned to sites that may not have been screened in.
31. Another issue was how sub-site information was aggregated to SPA level. On the latter point, the Applicant received advice from MS-LOT on the use of the MS Tool on 31st May 2022 which confirmed the three approaches to aggregation that are available in the Tool:
    1. Level 1 – no aggregation, outputs are at Seabird 2000 sub-site level.
    2. Level 2 – aggregated to Seabird 2000 site level.
    3. Level 3 – aggregation to SPA.
32. The advice stated that when using the aggregation option Level 3 the outputs for some SPAs are erroneous and that the “manual for the MS Apportioning Tool notes that this tool option is only for illustrative purposes”. However, the user manual of the R “apportionment tool” version 3 (Butler et al., 2020) states “that the tool now allows the user to directly output data at the level of an SPA”; HiDef used V3 and had used Level 3 prior to receiving the MS-LOT advice (31st May 2022).
33. The apportioning was re-run in the Tool using option Level 1. Using this option, weightings are provided against individual subsites. The subsites then need to be aggregated and manually assigned to their corresponding SPA. The list of subsites and assignment to SPAs are given in Annex C. Following the approach suggested by MS-LOT, apportioning percentages for each subsite assigned to the SPA were summed. For sub-sites that straddled SPAs all birds were assigned to the SPA; this was a precautionary approach but in the absence of sub-site boundary files was the only option available.

Non-breeding season

34. In the non-breeding season, seabirds are not tied to their breeding colonies, and many migrate to different regions or otherwise range widely. For all species, except guillemot and herring gull, non-breeding season birds were apportioned back to SPA breeding colonies using the information available in the report on BDMPS (Furness, 2015). The BDMPS and associated abundance estimates were derived using a combination of data on demography, migration, and modelled population age structure from the UK and overseas.
35. The relevant BDMPS for the proposed Project for most species, is the UK North Sea and Channel waters; the exception is kittiwake where the relevant BDMPS is the UK North Sea waters. For most species the apportioning estimate for the non-breeding season wind farm effects is a proportion derived from the number of adult birds from each of the SPA populations of interest, expressed as a proportion of the total BDMPS population. This is then repeated to estimate the proportion of immature birds, with the adult to immature ratio determined from the stable age structure of population models for each species (Tables in Appendix A of Furness (2015)).
36. For kittiwake at Coquet Island SPA and several species at Farne Islands SPA (herring gull, lesser black-backed gull and razorbill) the population of adults and immatures in the UK North Sea waters BDMPS (or North Sea and Channel) were not available in Appendix A of Furness (2015). For these colonies and species, the most recent colony count (Table 3.3) was multiplied by the proportion of adults from the “UK North Sea non-SPA colonies” which are estimated to occur in the BDMPS during the non-breeding season. The number of adults was then multiplied by a correction (total number of UK North Sea & Channel immatures / total UK North Sea & Channel adults) to determine the number of immatures associated with the SPA in the BDMPS. The resulting number of adults and immatures was then expressed as a proportion of the total BDMPS population (as per pt. 34).  
37. Non-breeding seasons have been defined according to NatureScot (2020). However, for the purposes of non-breeding season apportioning, seasonal adult and immature counts for the relevant BDMPS have been used for the BDMPS-defined seasons that best match those of NatureScot (2020). For kittiwake, gannet and razorbill the non-breeding season is more finely defined in Furness (2015) and apportioning weightings were derived accordingly (Table 3.3).
38. For guillemot, non-breeding season effects were apportioned against a regional population using the NatureScot approach (2018). The regional population is defined by the breeding season mean-max foraging range plus 1 SD, following NatureScot’s Scoping advice (4th February 2022), and follow-on advice based on the results of Buckingham et al. (2022) (20th May 2022). Whilst this approach is conservative in terms of the number of SPAs considered, use of the wider BDMPS may underestimate effects on regional SPAs given that this species does not disperse widely in the non-breeding season (Buckingham et al., 2022). In the Firth of Forth, guillemots may return to their breeding colonies as early as October (Harris et al., 2006; Forrester et al., 2007).
39. Similarly for herring gull, non-breeding season effects are apportioned against a regional population using the NatureScot approach (2018). The regional population is defined by the breeding season mean-max foraging range plus 1 SD, following NatureScot’s Scoping advice (4th February 2022). However, a correction was needed for the winter influx of continental breeding birds to eastern Scotland/UK. MSS advised (RM5; Technical Appendix 11.8) that the correction should be calculated from the proportions of overseas and western UK birds in the UK North Sea and Channel BDMPS (Furness, 2015). First the proportion of overseas breeders in the BDMPS was estimated; 135,130 birds from overseas populations within the BDMPS population of 466,511 (0.29), Secondly, the proportion of birds from western UK SPAs and non-SPA colonies within the BDMPS population was estimates (16,521/466,511 = 0.04). The final correction was the reciprocal of the sum of the proportions. The resultant correction (multiplier) 0.67 was used to adjust the number of estimated mortalities of herring gulls associated with each SPA after the apportionment had been undertaken and so is not apparent in the apportionment weightings shown for this species below.
40. For gannet, information on the proportions of birds migrating south or north from each colony based on tracking data of adults during the autumn and spring migrations (timings of which are defined by Furness (2015)) has been considered. The method follows that of McArthur Green (2015) for cumulative assessment of gannet collision risk in the UK North Sea and Channel at East Anglia THREE; the approach was subsequently used to apportion birds to gannet colonies for Seagreen (2019). For each colony, the method involved three steps:

• Step 1: Calculate the number of adult and immature birds from the SPAs moving north or south in the North Sea and Channel BDMPS during the relevant season (the “migrant population”) (Table 3.5);
• Step 2: Adjust the abundance of birds in the migrant population that will potentially pass-through Berwick Bank taking account of the location of the Project with respect to the colonies and proportion flying north/south (i.e., south flying birds at colonies south of Berwick Bank are subtracted from the migrant population whilst north flying birds are added; north flying birds from colonies north of Berwick Bank are subtracted and south flying birds are added); and
• Step 3: Finally, for each SPA, multiply the total number of SPA individuals (step 1) by the proportion of adults/immatures, and as a proportion of the total seasonal migrant population in the North Sea and Channel that may fly through the proposed Berwick Bank.
  41. The UK colony counts summarised in McArthur Green (2015) have, where possible, been updated in Table 3.5. These counts are consistent with those used for the NatureScot breeding season apportioning.
  42. From step 1, the abundance of gannets estimated within the North Sea and Channel that could migrate through Berwick Bank during autumn migration was 276,570 birds. During spring migration, the abundance increased to 299,879 gannets.

Table 3.5: Updated Table Based on McArthur Green (2015) Summarising Gannet Colony Sizes and Numbers of Birds Flying North or South in the North Sea and English Channel BDMPS. AON = Apparently Occupied Nests; Prop = Proportion.

4. Results

4.1. Breeding season: NatureScot method

43. The weightings derived for the breeding season were used to apportion mortality estimates to the SPAs and non-designated colonies. The apportionment also took account of age class information. For all species except the auks, age class information was derived from the data collected during the HiDef digital video surveys and reported in Technical Appendix 11.1: Ornithology Baseline.
44. For auks, the proportions of mature and immature birds for SPA populations were derived from the stable age structure of the population models developed and reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.

Herring gull

45. The weightings for apportioning breeding season herring gulls to SPAs are given in Table 4.1 and a full list of all colonies in Annex A.
46. The weightings were used to apportion the estimates of the number of adult and immature herring gulls impacted during the breeding season by collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.1: Apportionment of Herring Gulls to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

Lesser black-backed gull

47. The weightings for apportioning breeding season lesser black-backed gulls to SPAs are given in Table 4.2 and a full list of all colonies in Annex A.
48. The weightings were used to apportion the estimates of the number of adult and immature lesser black-backed gulls impacted during the breeding season by collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.2:  Apportionment of Lesser Black-backed Gulls to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

Puffin

49. The weightings for apportioning breeding season puffins to SPAs are given in Table 4.3   Open ▸ and a full list of all colonies in Annex A.
50. The weightings were used to apportion the estimates of the number of puffins impacted during the breeding season by displacement (Technical Appendix 11.4: Ornithology Displacement Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.3  Apportionment of Puffins to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

Gannet

51. The weightings for apportioning breeding season gannets to SPAs are given in Table 4.4 and a full list of all colonies in Annex A.
52. The weightings were used to apportion the estimates of the number of adult and immature gannets impacted during the breeding season by collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) and displacement (Technical Appendix 11.4: Ornithology Displacement Report) at each SPA and non-SPAs (Annex D).

Table 4.4: Apportionment of Gannets to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

4.2. Breeding season: MSs method

53. In the tables below, only those SPAs that were assigned a weighting greater than zero are summarised. The full list of SPAs presented as outputs by the MS Tool are given in Annex B.
54. Furthermore, those SPAs that are beyond the breeding season foraging range (mean max distance + 1 SD as per Woodward et al. (2019)) are given but identified *. Consequently, some SPA/species combinations included in the apportioning were not considered to have connectivity and were not screened in for assessment by the LSE screening exercise (SSE Renewables, 2021).

Kittiwake

55. The weightings for apportioning breeding season kittiwakes to SPAs are given in Table 4.5.The full outputs from the MS Tool are provided in Annex B.
56. The weightings were used to apportion the estimates of the number of adult and immature kittiwakes impacted during the breeding season by collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) and displacement (Technical Appendix 11.4: Ornithology Displacement Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.5: Apportionment of Kittiwakes to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

**Not provided as output in the MS Tool.

Guillemot

57. The weightings for apportioning breeding season guillemots to SPAs are given in Table 4.6. The full outputs from the MS Tool are provided in Annex B.
58. The weightings were used to apportion the estimate of the number of guillemots impacted during the breeding season by displacement (Technical Appendix 11.4: Ornithology Displacement Report) to each SPA and non-SPAs (Annex D).

Table 4.6:  Apportionment of Guillemots to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

* Not screened in based on breeding season foraging range.

**Not provided as output in the MS Tool.

Razorbill

59. The weightings for apportioning breeding season razorbills to SPAs are given in Table 4.7. The full outputs from the MS Tool are provided in Annex B.
60. The weightings were used to apportion the estimated displacement mortality of razorbills during the breeding season (Technical Appendix 11.4: Ornithology Displacement Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.7:  Apportionment of Razorbills to SPAs Which Include this Species As a Feature or As a Named Component of the Seabird Assemblage. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

*Not screened in based on breeding season foraging range.

**Not provided as output in the MS Tool.

4.3. Non-breeding season

61. For those species assessed at the scale of the relevant BDMPS, the tables below show those SPAs that were screened in based connectivity and those where the assigned weighting for the entire non-breeding season resulted in an apportioned mortality estimate of one bird or more; the full list of SPAs and weightings for those species assessed at the scale of the relevant BDMPS are given in Annex D.
62. For guillemot and herring gull, which were assessed at the regional population scale, the full list of weightings to SPA and non-SPA colonies is given in Annex A.

Kittiwake

63. The non-breeding season defined by NatureScot (2020) is approximated by the post-breeding migration (August-December) and return migration (January – April) of Furness (2015).
64. The weightings for apportioning non-breeding season adult and immature kittiwake to SPAs are given in Table 4.8 for the post-breeding migration, and Table 4.9 for the return migration.
65. The weightings were used to apportion the estimates of the numbers of adult and immature kittiwakes in the UK North Sea BDMPS during the non-breeding season by collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) and displacement (Technical Appendix 11.4: Ornithology Displacement Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.8: Apportionment of Mortality for Adult and Immature Kittiwakes within the UK North Sea BDMPS During the Non-Breeding Season (Post-breeding Migration: August - December). The Residual Weight Assigned to Non-SPA Colonies Is also Shown.              

Table 4.9:  Apportionment of Adult and Immature Kittiwake within the UK North Sea BDMPS During the Non-Breeding Season (Return Migration: January - April). The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

Herring gull

66. Apportioning of non-breeding season herring gulls from SPAs was carried out as per the breeding season using the NatureScot method. The weightings for apportioning non-breeding season impacts on herring gulls to SPAs are given in Table 4.10   Open ▸ .
67. The weightings were used to apportion the estimates of mortality from collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) to each of the SPAs and non-SPAs. The apportioned mortalities associated with each SPA were corrected (paragraph 38) to take account of the influx of birds from non-UK colonies.

Table 4.10: Apportionment of Adult Herring Gulls within a Regional Population During The Non-Breeding Season. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

Lesser black-backed gull

68. The non-breeding season defined by NatureScot (2020) is approximated by the autumn migration (August – October), winter (November - February) and spring migration (March – April) of Furness (2015).
69. The non-breeding season estimates of adult and immature birds impacted by collision were zero (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report). Therefore, apportioned mortality estimates to all SPAs for this species during the non-breeding season are all zero.
70. However, the weightings for apportioning non-breeding season lesser black-backed gull to SPAs are given in Annex D

Guillemot

71. Apportioning of non-breeding season guillemots from SPAs was carried out as per the breeding season using the NatureScot method and given in Table 4.11. Annex A has the full list of colonies.
72. The weightings have been used to apportion the estimates of the numbers of guillemots during the non-breeding season at risk of mortality from displacement (Technical Appendix 11.4: Ornithology Displacement Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.11  Apportionment of Guillemot within a Regional Population During the Non-Breeding Season. The Residual Weight Assigned to Non-SPA Colonies Is also Shown.

Razorbill

73. The non-breeding season defined by NatureScot (2020) is approximated by the autumn migration (August – October), winter (November - December) and spring migration (January - March) of Furness (2015).
74. The weightings for apportioning the non-breeding season razorbill to SPAs are given in Table 4.12 for the autumn and spring migrations, and in Table 4.13 for the winter.
75. The weightings were used to apportion the estimates of the numbers of adult and immature razorbills in the UK North Sea and Channel BDMPS during the non-breeding season at risk of mortality from displacement (Technical Appendix 11.4: Ornithology Displacement Report) to each of the SPAs and non-SPAs (Annex D).

Table 4.12:  Apportionment of Adult and Immature Razorbills within the UK North Sea and Channel BDMPS During the Non-Breeding Season (Autumn and Spring Migrations: August – October, January – March).

Table 4.13: Apportionment of Adult and Immature Razorbills within the UK North Sea and Channel BDMPS During the Non-Breeding Season (Winter: November - December).

Gannet

76. The non-breeding season based on NatureScot (2020) is approximated by the autumn migration (October to November) and spring migration (December to March) of Furness (2015).
77. The weightings for apportioning the non-breeding season gannet to SPAs are given in Table 4.14 for the autumn migrations, and in Table 4.15 for the rest of the spring migration.
78. As the proportions of birds from each SPA flying north/south changes depending on the migration period, so too does the proportion of birds at risk of collision with the Proposed Development Apportioning was therefore carried out separately for the autumn and spring migrations, and the weightings used to apportion the estimates of adult birds in the UK North Sea and Channel BDMPS by collision (Technical Appendix 11.3: Ornithology Collision Risk Modelling Report) to each of the SPAs in Appendix 11.6 Ornithology Population Viability Analysis Technical Appendix for each migration period.

Table 4.14: Apportioning of Gannets within the UK North Sea and Channel BDMPS during Autumn Migration (September to November) (Furness, 2015).

Table 4.15:  Apportioning of Gannets within the UK North Sea and Channel BDMPS during Spring Migration (December to March) (Furness, 2015).