Appendix 10 Offshore and Intertidal Ornithology – Baseline Environment
10.1 Desktop Study
- An initial desk-based review of literature and data sources to support this Offshore EIA Scoping Report has identified a number of baseline datasets in the form of pre-existing, site-specific and non site-specific datasets. These are summarised in Apx. Table 10. 1 Open ▸ . Other relevant sources of data will be sought as the assessment progresses and all such sources of information will be referenced appropriately in the Offshore EIA Report.
Apx. Table 10. 1: Summary of Key Desktop Reports to Inform Ornithology Scoping Assessment
10.1.1 Site-Specific Survey Data
- The primary data source used to inform the offshore and intertidal ornithology EIAR Assessment for the Proposed Development will be the 25 monthly digital aerial transect surveys conducted between March 2019 and April 2021.
- The aerial survey area encompasses the Proposed Development Proposed Development Array Area, plus a 16 km buffer, which makes up the Offshore Ornithology Study Area, and covers nearly 5,000 km2 (Apx. Figure 10. 1 Open ▸ ). The aerial surveys are carried out using multiple aircraft in a single day to reduce potential variation associated with movement of birds between different days.
- The surveys follow the standard HiDef digital video aerial survey method for recording birds, conforming with guidance of Thaxter and Burton (2009) and updated in Thaxter et al. (2016).
- Surveys are targeted at times of day that excludes 1.5 hours of sunrise and sunset in summer and 1 hour in winter. The dawn and dusk periods are excluded because the sun angle is too low for digital imagery and often the light levels are too low at this time of the day. The surveys are randomised with respect to state of tide.
- Thirty seven transects across the Offshore Ornithology Study Area are spaced 2 km apart. The aircraft carries four cameras recording continuously across the survey area transects, each surveying a strip width of 125 m. Data from two of the cameras are analysed, with the other two providing back up data in case of failure, or to provide additional spatial coverage where necessary. The survey therefore achieves 12.5% coverage of the survey area.
- The aerial survey methods were discussed and agreed with MS and NS following meetings held on 18 December 2019 and 26 February 2020.
- During April 2019 poor weather stopped any surveys from being undertaken that month. In April 2020, restrictions in place due to Covid-19 meant no survey could be undertaken that month. Following advice received from Marine Scotland Science and Nature Scot an additional two surveys were undertaken in April 2021, ensuring that two separate sets of survey data are available for the month of April, albeit obtained within the same year. The use of the data from these two April surveys has been agreed through the Road Map process.
- In January 2020, poor weather again meant that no flights were able to be undertaken during that month. A survey was undertaken as soon the weather allowed, on 5 February, and these data will be used as the January data. At this time of year there is not expected to be any significant changes in the spatial distribution or density of seabirds within the five days between the end of January and when the survey was undertaken. A later survey was undertaken on 19 February and will be used as February data. The use of the early February survey data as January data has been agreed through the Road Map process.
- During some of the surveys, logistical issues prevented full coverage of the survey transects. To account for ‘missing transects’ within the data set, two remedial measures are used: (i) additional data from the extra cameras on other transects near the missed area are analysed to improve the spatial coverage of the survey sample and (ii) for key species present in sufficient abundance, the MRSea model is used to predict the surface density of birds in the survey area. As the time of writing, the use of the MRSea model was proving problematic due to the size of datasets involved and bugs in the programming which were yet to be resolved. Should the MRSea model prove unsuitable, design-based abundance estimates would be used instead.
- Consideration is being given to appropriate modelling and statistical analyses to help take account of aerial survey data gaps, and the approaches being considered will be the subject of on-going consultations with Marine Scotland, NatureScot and the RSPB.
- For each bird detected, a record is made of the observation time and location, species group, species (where identification can be made to species level), number of individuals, age class, behaviour, flight direction and association (e.g. with fishing vessels).
- The aerial survey data extending out to 16 km from the Proposed Development Array Area will be used to generate density estimates for the most frequently recorded bird species within the Offshore Ornithology Study Area using either the MRSea modelling application or design-based abundance estimates.
- Seagreen, NnG and Inch Cape also commissioned combined aerial surveys from May 2019 to September 2020 (as well as separate surveys at the three sites in April 2019 and surveys at Seagreen and NnG in March 2019) as part of their pre-construction baseline, with a survey area that overlaps part of the Berwick Bank Offshore Ornithology Study Area. Having been carried out by the same contractor (HiDef) and utilising the same survey design and transect orientation, these data are directly comparable and complementary to the Berwick Bank aerial surveys and may be used to provide wider context to the Berwick Bank survey data, by comparing the density/abundance of seabirds in the overlapping areas of survey. Use of data from the combined developments at Seagreen, NnG and Inch Cape may also be used in the approach to cumulative impact analysis.
- The following secondary data sources will be used to provide relevant supplementary contextual information on the Proposed Development and surrounding buffer area:
- boat-based transect survey data from July and August 2020 and between April and May 2021 within the Proposed Development Array Area targeted at recording seabird flight height and behaviour and collecting associated environmental variable data;
- boat-based transect survey data of the Firth of Forth Round 3 Zone from December 2009 to November 2011;
- seabird colony data and seabird tracking data collected between 2010 and 2019; and
- intertidal bird surveys at the landfall locations on the North Berwick coast between September 2020 to March 2021.
Boat-Based Seabird Surveys (2020 to 2021)
- Additional boat-based surveys were undertaken in July and August 2020 and between April and June 2021 to specifically obtain site-specific flight height (and behavioural) data to inform collision risk modelling (CRM) for the Proposed Development.
- This programme of surveys was originally planned for 2020, however commencement was delayed due to the COVID-19 pandemic. As a result, a revised programme of surveys was undertaken across the 2020 and 2021 breeding seasons.
- The survey method broadly followed Embling et al. (2012). This included repeatedly sampling locations along a continuous transect route to assess the effect of variable factors (e.g. tidal state) on bird density, or utilisation of a specific area. In a deviation from Embling et al. (2012), four spatially independent sites in the Proposed Development Array Area, each separated by at least 5 km, were surveyed using two parallel 15 km line transects separated by a 3 km gap. Each of the four sites were surveyed over a day during suitable weather conditions, once per month (in July and August 2020 and in April, May and June 2021). During each one-day survey the transect routes were repeatedly surveyed between sunrise and sunset to cover the daytime component of the diel cycle when birds can be surveyed visually. Each transect was repeated four times during each survey, with repeats being spread throughout the day at dawn, mid-morning, mid-day, mid-afternoon and ending at dusk. The time between runs was used to collect additional flight height data using a rangefinder.
- Flight height data collection followed the methods applied during surveys of the Seagreen Phase 1 Wind Farm in 2017 (Seagreen 2018) and published by Harwood et al. (2018). All surveyors visually estimated flight heights of all birds seen in snapshots or line transect in 5 m bands (i.e., >0-5, >5-10, >10-15, etc). Surveyors also utilised optical laser rangefinders (Nikon Forestry Pro) to provide more detailed measurements when they were not surveying the line transect or if very few birds were present. The rangefinder records form the basis of the flight height distribution dataset, whilst the visual height assessments provide a larger pool of data for comparison. All surveyors received training in the correct use of the rangefinders prior to the start of the surveys.
- The survey team included a dedicated surveyor tasked with collecting as many rangefinder flight height observations as possible. To increase the capacity for rangefinder flight height observations, two additional laser rangefinders were used opportunistically by the other observers in the survey team. However, surveyors always prioritised the basic line transect survey to ensure that no birds were missed. Where possible, a GPS waypoint was associated with records to allow spatial referencing and linking with environmental data collected at the time of the measurements.
- The dedicated rangefinder operator continually scanned for potential seabird targets. As soon as a potential target bird appeared, attempts were made to measure its flight height. The rangefinder operator aimed to take a measurement of every bird that came into range of the instrument. Due to discrepancies in size, the range at which larger species such as gannet or great black-backed gull can be measured is greater than that for smaller species such as kittiwake. When a range of species were present, preference was given to kittiwake and gannet, the key species to be assessed using CRM. However, due to those species occurring so frequently and being well represented in the data, different species (e.g. terns and skuas) were also selected if the opportunity arose. Typically, there were relatively few potential targets available at any one time, so data was collected for most birds that came within range. However, when swamping occured the primary objective was to acquire as many verified flight heights as possible and targets deemed most likely to yield data were selected (i.e. that can be easily targeted with the rangefinder).
- Following Cook et al. (2018), Normal, log-normal, gamma, normal-mixture and gamma-mixture distribution were fitted to the rangefinder data using the mixtools (Benaglia et al. 2009) and fitdistrplus (Delignette-Muller and Dutang, 2015) packages in the R statistical package (R Core Team, 2021). The best fitting distribution was selected based on visual appraisal to derive flight height distribution curves.
- From the visual observation height estimates, the proportion of records in each 5 m height band were categorised, which will allow an overall estimate of the proportion of birds deemed to be below and at rotor-swept height for use in the Band CRM.
- Based on preliminary analysis derived from the surveys in July and August 2020, it was found that Kittiwake flight height distribution differed considerably from the Johnston et al. (2014) fit but found reasonable agreement with the distribution derived from aerial survey data. However, the Gannet fit from the rangefinder data mainly differed from the Johnston et al. (2014) and digital aerial fits in the first 5 m above the sea, possibly due to Johnston et al. (2014) data being lumped in categories and due to possible errors at that height associated with digital aerial surveys.
- The survey methods for the boat-based surveys undertaken in 2020 and 2021 were agreed with ornithological advisors at MS and NS at meetings held on 26 February 2020 and 28 April 2020.
- As the data were obtained primarily for the specific purpose of obtaining flight height data over a very defined period of time and were collected using a different survey platform, the data will not be combined with the aerial survey data for wider assessment purposes. However, densities of seabirds recorded during these surveys, along with the additional information recorded, will be used as supplementary contextual information.
Boat-Based Transect Surveys (2009 to 2011)
- The original 2009 to 2011 boat-based surveys were carried out for the first phase of baseline data collection for the former Firth of Forth Zone. As this dataset is now over ten years old and the abundance of seabirds may have changed since the data were collected, it will be used to provide contextual information to support the primary data source, which is the digital aerial surveys undertaken between March 2019 and April 2021.
- A total of 23 monthly boat-based transect surveys were undertaken between December 2009 and November 2011, covering the former Firth of Forth Zone (Apx. Figure 10. 1 Open ▸ ), which includes the boundary of the Proposed Development. Transects were spaced 3 km apart and oriented northwest to southeast to intercept the likely predominant flight lines from major breeding colonies in the Firth of Forth.
Apx. Figure 10. 1: Boat-based Survey Area 2009 to 2011
Seabird Colony and Tracking Data
- Relevant recent counts of breeding seabirds at UK colonies will be used as reference populations in the EIAR assessment. These will be sourced from the online Seabird Monitoring Programme website (BTO, 2021). In addition, the assessment will also refer to relevant data from ongoing tracking studies that are being undertaken by the Centre for Ecology and Hydrology (CEH) and University of Leeds as part of the monitoring proposals for the combined Forth and Tay developments: Seagreen 1, Neart na Gaoithe and Inch Cape along with Berwick Bank, under advice from the Forth and Tay Regional Advisory Group Ornithology subcommittee. It is anticipated that relevant data from these studies collected between 2010 to 2019 will be made available to inform the Proposed Development ornithology EIA. Species for which GPS tracking data are available include guillemot, razorbill and kittiwake from both the Isle of May and from Fowlsheugh and St Abb’s Head. Gannet tracking data is available from breeding birds on the Bass Rock. While data was collected in 2020 and 2021, it is considered that this data will not be analysed in time to be included in the EIAR assessment for the Proposed Development.
- In addition to the above tracking studies, a programme to track breeding kittiwakes using Global Positioning System (GPS) tags was due to commence in 2020 to provide colony-specific data on seabird movements from the colonies at St Abb’s Head to Fast Castle SPA and Fowlsheugh SPA. Due to the impact of the COVID-19 pandemic however, this tagging programme did not commence until 2021 It is considered that this data will not be analysed in time to be included in the EIAR assessment for the Proposed Development.11. Apx. Table 10. 2 Open ▸ summarises the recent tracking data for the Forth and Tay region.
Apx. Table 10. 2: Seabird Tracking Studies in the Forth and Tay Region.
Non-Breeding Season Intertidal Surveys (2020 to 2021)
- The programme of monthly intertidal and nearshore coastal bird surveys was conducted over a period of 12 months between July 2020 and June 2021 inclusive. Surveys covered the non-breeding season when the largest numbers of birds were expected to be present (approximately September to March, covering the autumn migration period as well as the winter months), as well as the breeding and post-breeding periods.
- In order to cover the two potential cable landfall sites, the Intertidal and Nearshore Coastal Bird Survey Area covered two separate sections of coast covering a total of approximately six kilometres. Each section consisted of two count sectors, extended out to 1.5 km from the MHWS mark. To identify the distribution of birds, the count sectors were segregated into three distance bands; 0 - 500 m, 500 m - 1 km and 1 km - 1.5 km (Apx. Figure 10. 1 Open ▸ ).
- During each survey the birds present along the foreshore and nearshore coastal waters were counted and ascribed to one of the three distance bands. Surveys covered a range of different tidal conditions throughout the survey programme. Survey methods were based on the high tide (core count) methodology of the BTO/JNCC/RSPB/WWT WeBS scheme. This involved the surveyor counting birds from vantage points along the coast using binoculars and a telescope. Weather conditions were also recorded during surveys.
Designated Conservation Sites
- A number of sites of nature conservation importance for birds have been identified as occurring in close proximity to the Proposed Development. Apx. Table 10. 3 Open ▸ provides an early indication of the key designated SPAs for breeding seabirds that are within closest proximity to the Proposed Development, and therefore where there is likely to be the greatest potential for effect. These SPAs will require consideration within the EIA and HRA. In addition, this list will be refined in the EIA to include all SPA sites that are within mean maximum foraging range (+1S.D.) based on foraging ranges presented in Woodward et al., 2019). A full screening of Natura 2000 sites with qualifying seabird interest features will also be undertaken in the LSE Screening Report for the Proposed Development. Relevant seabird notified interest features of Natura 2000 sites screened into the ornithology assessment will be fully considered and assessed in the ES section with the assessment on the Natura 2000 site itself deferred to the Report to Inform Appropriate Assessment (RIAA). Most recently available colony counts for the key species from the Seabird Monitoring Programme website will be used in these assessments.
- The screening to be undertaken in the ornithology EIA Report section will also include national designations, including Sites of Special Scientific Interest (SSSIs) and Nature Conservation Marine Protected Areas (MPAs).
Apx. Table 10. 3: Summary of Protected Areas for Seabirds Nearest to the Proposed Development
10.1.3 SUMMARY OF Survey results
Summary of Interim Analysis of Aerial Survey Data
- Interim analysis of the aerial survey data collected between March 2019 and September 2020 indicated that the five most frequently recorded species occurring within the survey area over this period were guillemot, kittiwake, razorbill, gannet and puffin. A further three species (Arctic tern, herring gull and lesser black-backed gull were recorded regularly but in lower numbers between March 2019 and September 2020. A similar suite of species were recorded on boat-based surveys in the study area in July and August 2020, when guillemot, kittiwake, gannet, Arctic tern, razorbill, puffin, herring gull and fulmar were the most frequently recorded species.
- A summary of the five most frequently recorded species based on recent surveys in the Offshore Ornithology Study Area is presented below. Further analysis of density and abundance results using the full 25 month aerial survey dataset is currently being undertaken.
- During 2019 and 2020 aerial surveys, guillemots were recorded in the Offshore Ornithology Study Area in all survey months, with lowest numbers recorded between September and December inclusive. Interim analysis of this aerial survey data showed that following the winter period when numbers were lowest, guillemot numbers increased in early spring as adult birds returned to the nearby breeding colonies to re-establish pair bonds and territories. Although there were fluctuations, numbers recorded in the Offshore Ornithology Study Area remained high for the breeding season, and post-breeding period, when both adults and juveniles move away from the colonies. Density maps for the survey period showed that guillemots were distributed throughout the Offshore Ornithology Study Area in the breeding season, with lower, more patchy densities recorded during the non-breeding season (SSE, 2021).
- During 2019 and 2020 aerial surveys, kittiwakes were recorded in the Offshore Ornithology Study Area in all survey months, although numbers fluctuated considerably between months, seasons and years. Lowest numbers were recorded during the mid-winter period (November/December) when kittiwakes tend to be widely dispersed in the North Atlantic and North Sea (Mitchell et al., 2004). Numbers increased from January onwards, with peak densities occurred during the early spring (2019) and in the post-breeding period in August and September (2020). Density maps for the survey period showed that although kittiwakes were widely distributed throughout the Offshore Ornithology Study Area in both the breeding and non-breeding seasons, there were hotspot areas where higher densities were recorded. These hotspots were potentially linked to areas of shallower bathymetry and may have been feeding areas, although this is still being analysed (SSE, 2021).
- Aerial surveys recorded razorbill density fluctuating considerably across months and between years, although numbers between November and February were consistently low, as razorbills are dispersed along the Atlantic coast of Europe in the winter months (Merne, 2002). Recorded numbers increased from March onwards, as adult razorbills returned to the colonies for the breeding season. Numbers fluctuated in both the 2019 and 2020 breeding seasons but showed peaks in both post-breeding periods in August and September, as adult and young razorbills moved away from the colonies. Density maps for the survey period showed that razorbills were widely distributed at predominantly low densities throughout the Offshore Ornithology Study Area in both the breeding and non-breeding seasons, with some localised areas where higher densities were recorded. These hotspots were potentially linked to areas of deeper bathymetry, and may indicate feeding areas, although this is still being analysed (SSE, 2021).
- Aerial survey data for gannet showed relatively consistent seasonal and inter-annual variation in densities, with very low numbers recorded between December and February inclusive. In both the 2019 and 2020 breeding seasons, numbers in the Offshore Ornithology Study Area increased from March onwards, as breeding adults returned to the Bass Rock. Numbers peaked in July and August, before decreasing again from September. Density maps for the survey period showed that gannets were widely distributed at predominantly low densities throughout the Offshore Ornithology Study Area in both the breeding and non-breeding seasons, with higher densities in the breeding season, although no obvious hotspot areas (SSE, 2021).
- Aerial surveys recorded puffin density fluctuating considerably across months and between years, although birds were recorded on all surveys. Lowest numbers were recorded in November and December, with numbers increasing again from January onwards. Numbers were fairly consistent across all months of the 2019 breeding season and post-breeding season, but showed larger peaks in March, August and September of 2020. The drivers behind these differences are not presently clear but will be considered during the analysis of the full aerial survey dataset. Density maps for the survey period showed that puffins were widely distributed at low to moderate densities throughout the Offshore Ornithology Study Area in both the breeding and non-breeding seasons, with some localised areas where higher densities were recorded (SSE, 2021).
- The aerial survey data identified relatively small numbers of Arctic tern but did include a greater number of terns categorised as either common or Arctic terns. Based on results from the 2020 boat-based surveys in July and August it was considered that the post-breeding movement is likely to relate to Arctic tern. Further analysis of Arctic tern density and abundance results using the full aerial survey dataset is currently being undertaken (SSE, 2021).
- Initial results from the aerial surveys indicate herring gull were present in relatively low numbers predominantly in the breeding season. The 2020 boat-based surveys also confirmed relatively low herring gull presence on surveys in July and August. Further analysis of herring gull density and abundance results using the full aerial survey dataset is currently being undertaken (SSE, 2021).
- During aerial surveys lesser black-backed gulls were present in relatively low numbers, while the July and August 2020 boat-based surveys further confirmed this at this time of year. However, lesser black-backed gull populations at the Forth Islands Special Protection Area (SPA) have the potential for connectivity with the Berwick Bank project. Further analysis of density and abundance results using the full aerial survey dataset is currently being undertaken (SSE, 2021).
Summary of Intertidal Surveys
- A total of 54 species were recorded within the Intertidal and Nearshore Survey Area during the survey programme (RPS, 2021). Eider were recorded in every survey month, with typical sightings involving up to 30 birds within 1km of the shore. Common scoter and red-breasted merganser were recorded infrequently, with other wildfowl species recorded intermittently.
- Oystercatcher was the most abundant and regularly present wader species throughout the Intertidal and Nearshore Survey Area, with birds recorded in almost every month of the survey programme. Numbers typically ranged between approximately 10 and 60 individuals. Turnstone, curlew, dunlin, redshank and ringed plover were also recorded regularly in lower numbers. Other wader species including greenshank, purple sandpiper, bar-tailed godwit, grey plover, knot, lapwing and golden plover were recorded infrequently.