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2nd December 2013

WALNEY

EXTENSION

OFFSHORE

WIND FARM

Walney Extension Offshore Wind Farm

Offshore Ornithology

Clarification Note: Cumulative Impact Assessment Source

Data


Clarification Note – Cumulative Impact Assessment source data

2nd December 2013 Page ii

PINS Reference: EN010027


Clarification Note– Offshore Ornithology: Cumulative Impact Assessment Source Data

DONG Energy Walney Extension (UK) Ltd.

33 Grosvenor Place, Belgravia, London, SW1X 7HY

Version: 2

Date: 2nd

December 2013

© DONG Energy Power (UK) Ltd. 2013. All rights reserved.

Pictures: © DONG Energy Power (UK) Ltd., 2012.

Prepared by: Matthew Hazleton and Robin Ward (NIRAS Consulting Ltd)

Checked: Ian Ellis and Robin Ward (NIRAS Consulting Ltd)

Accepted: Allen Risby (DONG Energy)

Approved: Sally Holroyd (DONG Energy)

Doc no. 1677853

Revision history

Version Date Author History

1 26/11/2013 Matthew Hazleton (NIRAS)

2 02/12/2013 Matthew Hazleton (NIRAS)

mailto:[email protected]



2nd

December 2013 Page 1

1 Introduction

1.1 DONG Energy Walney Extension (UK) Ltd. (“the Applicant”) made an Application to the

Planning Inspectorate (PINS) on 28th June 2013 for a Development Consent Order (DCO) for

the Walney Extension Offshore Wind Farm ("the Project") located in UK waters in the Irish Sea

between Cumbria and the Isle of Man.

1.2 This Paper responds to comments made in the Natural England / JNCC Relevant Representation

(dated 20th September 2013, paragraphs 5.1.1.6 and 5.1.2.4) and provides a discussion on the

evidence used to inform the ornithological Cumulative Impact Assessment (CIA) within Chapter

15 of the Walney Extension Environmental Statement (PINS document reference 10.1.13) and

Annex 2 of the Walney Extension Habitats Regulations Assessment Report (PINS document

reference 7.2).

1.3 The paper provides an overview of the collision and displacement assessments provided in the

Environmental Impact Assessments (EIAs) of wind farm projects within the Irish Sea. The paper

then provides details of data availability and applicability from these projects in terms of their

utilisation to inform the Walney Extension EIA. The Paper provides a judgment on the level of

confidence that can be assumed in the assessment of collision and displacement effects.

1.4 This Paper also provides clarity through the cumulative assessment with regards to the recently

published tiered approach to assessment (JNCC and Natural England, 2013).

1.5 The Paper focuses on cumulative impacts via operational phase collisions with turbine rotors

and highlights two key species: lesser black-backed gull and herring gull. Also discussed is the

data sourced to inform cumulative displacement analysis for Manx shearwater, red-throated

diver, guillemot and razorbill.

2 Background

Environmental Impact Assessments of Irish Sea Wind Farms

2.1 The ten wind farms in the Irish Sea considered as part of the cumulative impact assessment for

Walney Extension are detailed in Table 1. These projects cover a 10 year operational period,

between 2003, when North Hoyle became operational, and 2013 when two Projects in addition

to Walney Extension, are currently in planning (Burbo Bank Extension and Rhiannon).

Table 1: Wind farms considered within the cumulative impact assessment for Walney Extension

Project Status Year Operational

North Hoyle Operational 2003

Barrow Operational 2006

Burbo Bank Operational 2007

Rhyl Flats Operational 2009

Walney I & II Operational 2011/12

Ormonde Operational 2011

West of Duddon Sands In construction n/a

Gwynt y Môr In construction n/a



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Project Status Year Operational

Burbo Bank Extension In planning n/a

Celtic Array SE (Rhiannon) In planning n/a

2.2 The time span between the assessments of impacts on ornithological interests between 2003

and 2013 has included significant developments to the analytical techniques used to explore

effects such as collision and displacement. This has therefore given rise to differing information

presented (in terms of both quantity and quality) within the Environmental Statements of the

offshore wind farms produced during this time.

2.3 This paper reviews the source data available for each Irish Sea project and highlights the quality

and applicability of the following core information that may be used to inform a cumulative

collision risk assessment :

Species abundance data

Species population size / density estimates

Flight height data

Identification of Collision risk model used and avoidance rate applied

Estimates of displacement and resultant mortality

2.4 Count and abundance data refers to simple statements relating to the number of individuals of

each species recorded in each survey. This basic presentation of data does not refer to

population size and density estimates which are extrapolated to the entire survey area and

generally corrected for distance errors. The Band (2012) collision risk model developed for

offshore wind assessments utilises monthly species densities as a foundation to the model.

2.5 Flight height data required to inform a CRM involves a Proportion of birds at Collision Height

(PCH).

Collision risk modelling

2.6 Collision risk models developed by Bill Band have involved several incarnations since their

initial use in c.2000. The initial model (ultimately published as Band, 2006) was designed for

use on onshore sites and involved the input of monthly records of time spent at potential

collision height (PCH) by relevant species. It was not until 2011 that a model specifically

designed for offshore wind assessments was developed (Band, 2011). Therefore, collision

assessments of offshore projects undertaken prior to 2011 generally utilised the 2000 or 2006

model. The 2011 model uses, as primary data input, monthly species densities to reflect the

outcomes of the survey techniques applied at offshore sites. A 2012 update to the model

(Band, 2012) included additional aspects including an ‘extended model’ exploring flight height

distribution within PCH and options to incorporate tidal variation. This ‘extended model’ was

incorporated into two Options within the Band (2012) CRM termed Option 2 and Option 3.

Option 1 within the model carried out the same analysis as included in the Band (2011) CRM

incorporating what is now termed the ‘basic model’.

2.7 The ‘default’ avoidance rate considered appropriate in the modelling process has also varied

over recent years. Avoidance rate is the probability of a bird taking avoidance action when



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encountering a turbine (Chamberlain et al., 2006). Prior to 2011, a default avoidance rate of

95% was suggested for all species by Scottish Natural Heritage (SNH), with this being updated

to 98% in 2011 (SNH, 2010). However, there is few empirical data on species avoidance,

particularly for seabirds. Some studies have suggested higher avoidance rates for certain

species e.g. 99.4% for gannet (Krijgsveld et al., 2011) and 98.83% for Sandwich tern (DECC,

2011). The default avoidance rate (98%) is applied to the number of transits through the rotors

of an offshore wind farm, significantly reducing the collision risk estimate to a level which is

believed to represent the actual number of collisions that will occur per annum.

2.8 The minimum requirement to inform and contribute to collision CIA, are population size /

density estimates even if no collision estimates are presented in the relevant project EIA. This

allows the implementation of Band (2012) modelling to provide indicative collision results.

Should collision estimates be provided at an inappropriate avoidance rate in the assessment

for a Project, simple calculations can revise the estimate.

Displacement analysis

2.9 Where given estimates of displacement (and resultant mortality) are not available for a project

population estimates are the minimum requirement in order to allow some indicative results to

inform a CIA. Guidance relating to displacement has recently been published (Natural England

and JNCC, 2012) so that quantified displacement assessments are generally absent from EIAs

prior to this time.

2.10 The interim guidance published by Natural England and JNCC (2012) suggests that analysis of

displacement should be carried out using a matrix approach incorporating mean-maximum

population estimates covering the breeding period, the non-breeding period and where

applicable, the post-breeding moult period. The guidance suggests population estimates should

cover the wind farm area plus a 2 km buffer for all species except seaducks and divers for

which a 4 km buffer should be used.

2.11 There is currently little evidence to support displacement and mortality predictions within the

matrix approach. As such, where displacement analysis has been conducted displacement and

mortality rates may differ between projects depending on the evidence base used to define

such rates.

Tiered approach to cumulative impact assessment

2.12 Recent guidance on the presentation of cumulative impact assessment suggested the

application of a tiered approach when considering data from other wind farm sites in order to

determine the confidence in the assessment performed (JNCC and Natural England, 2013).

Following this guidance each wind farm is designated to one of six tiers, where lower tiers

represent sites where there is an increased level of confidence in the data available. This

implies that projects in lower tiers have adequate environmental characterisation data through

both impact assessment and monitoring that projects in higher tiers may lack. This does not

however account for the potential data limitations as highlighted above.



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2.13 Descriptions of each tier (as defined by JNCC and Natural England, 2013) are shown in

Appendix 1. Table 2 presents the allocation of tiers to the Irish Sea projects by taking account

of the status of a project and the availability of environmental characterisation data.

Table 2: Allocated tiers to wind farms considered within the cumulative impact assessment for

Walney Extension

Project Status Tier

North Hoyle Operational 1

Barrow Operational 1

Burbo Bank Operational 1

Rhyl Flats Operational 1

Walney I & II Operational 1

Ormonde Operational 1

West of Duddon Sands In construction 2

Gwynt y Môr In construction 2

Burbo Bank Extension In planning 4

Celtic Array SE (Rhiannon) In planning 5

2.14 The assessment for North Hoyle Offshore Wind Farm was undertaken in 2002 (NWP Offshore,

2002). This work was therefore carried out before both the widespread use of the Band model

and the publishing of guidance concerning displacement. A qualitative assessment was carried

out for collision risk modelling with the assessment presenting the proportion of observations at

PCH for a select few species (red-throated diver, common scoter, cormorant). No population

estimate / density information was presented. North Hoyle Wind Farm is included in Tier 1 of

the Tier 1 to 6 model.

2.15 The assessment for Burbo Bank Offshore Wind Farm was undertaken in 2002 (Seascape Energy,

2002) and as such this project is included in Tier 1. This work was therefore carried out before

the widespread use of the Band model and the publishing of the displacement guidance. A

qualitative assessment was carried out in presenting the proportion of observations at PCH,

although not all species are included (large gull species are absent). No population estimate /

density information is presented. Similarly, the assessments of Barrow Offshore Wind Farm

were undertaken during a similar time period and no data beyond basic abundance information

is presented (Warwick Energy, 2002).

2.16 Walney I and II Offshore Wind Farm (considered as a single wind farm) was assessed in 2006

(RPS, 2006a) and incorporated collision risk modelling for lesser black-backed gull (in addition to

pink-footed goose and whooper swan) using the Band (2000) model. Avoidance rates are given

at a range between 0 and 99.99% (although 98% is not presented). The assessment also

presents peak monthly abundances corrected for distance and survey coverage which can be

used to provide an indication of monthly collision risk. As environmental characterisation data

are available and pre- and post-construction monitoring surveys have been completed, Walney I

and II is designated a Tier 1 project.



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2.17 The ornithological assessment of Ormonde Offshore Wind Farm was completed in 2005

(Ecology Consulting, 2005). Although collision risk modelling (via Band, 2000) was undertaken

the presentation of results is in graphical form with avoidance rate plotted against change in

background mortality, so that absolute values require interpretation. Annual peak and mean

population estimates are presented although monthly counts are again, only presented

graphically. As environmental characterisation data are available and the project is now fully

operational, Ormonde is designated a Tier 1 project.

2.18 West of Duddon Sands Offshore Wind Farm was assessed in 2006 (RPS, 2006b) with the

methodology following that used for Walney I and II. Collision estimates are provided for lesser

black-backed gull (and pink-footed goose, whooper swan), while monthly peak counts and

percentage flights at collision height (PCH) values are provided for other species. Environmental

characterisation data are available for West of Duddon Sands although the project is still in the

construction phase. As such West of Duddon Sands is designated a Tier 2 project.

2.19 Rhyl Flats was fully commissioned in 2009 following an assessment undertaken in the early

2000s. There does not appear to be any data available for this project that quantifies the

collision risk posed to lesser black-backed gull. There is also a lack of density or population

estimate data which could provide a qualitative description of collision risk at the site. Rhyl Flats

is designated a Tier 1 project.

2.20 Gwynt y Môr Offshore Wind Farm was assessed in 2007 (Npower renewables, 2007) although

no collision risk modelling was undertaken. In addition, no attempt is made to provide

population estimate or density data with only indicative abundances provided. An Appropriate

Assessment for Gwynt-y-Môr was published in 2008 (BERR, 2008). This presents collision risk

estimates for Gwynt-y-Môr and also details collision risk values for North Hoyle, Rhyl Flats and

Burbo Bank. Although not presented an avoidance rate of 98% can be calculated to inform the

cumulative assessment. Gwynt-y-Môr is yet to be fully commissioned and, as such, is designated

a Tier 2 project.

2.21 Burbo Bank Extension Offshore Wind Farm was assessed in 2013 (DONG Energy, 2013). The

collision estimates are based on Band (2012) and are presented using Options 2 and 3 of the

CRM (NIRAS Consulting, 2013). Displacement analysis for Burbo Bank Extension followed the

guidance published by Natural England and JNCC (2012). All four of the species included in the

displacement analysis for Walney Extension (red-throated diver, Manx shearwater, guillemot

and razorbill) were incorporated into the analysis for Burbo Bank Extension. The analysis used

mean-maximum population estimates for the breeding, non-breeding and when applicable a

post-breeding moult period. Population estimates used within the analysis represented birds

recorded in the wind farm area plus a 4 km buffer area. Environmental characterisation data are

available for Burbo Bank Extension although the project is currently in the examination phase.

As such, Burbo Bank Extension is designated a Tier 4 project.

2.22 The Zonal Appraisal and Planning (ZAP) report of the Irish Sea Zone (Centrica Energy, 2012)

presents initial collision results for the three proposed development zones in this area, including

Rhiannon, for selected species (including lesser black-backed and herring gulls) based on the

Band (2011) model. The Rhiannon Project within the ISZ is currently pre-application and is

designated a Tier 5 project.



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3 Cumulative collision risk for Walney Extension offshore wind farm

Herring gull

3.1 Herring gull is a qualifying feature at only one SPA within foraging range of Walney Extension,

Morecambe Bay SPA. As such, only those offshore wind farm sites within the foraging range of

herring gull from Morecambe Bay SPA are included in the cumulative assessment.

3.2 Table 3 presents the availability of herring gull collision data from assessments of Irish Sea wind

farms. Collision risk estimates are limited to Burbo Bank Extension (Tier 4) with the potential for

interpreting collision estimates from the Ormonde (Tier 1) assessment. For Walney I & II (Tier 1)

and West of Duddon Sands (Tier 2), the relevant assessments state that with regards to herring

gull, ‘the number of birds observed flying at rotor height within the proposed wind farm area

was sufficiently low to conclude that the magnitude of collisions will be negligible’ (RPS 2006a &

b). Qualitative evidence from these projects is discussed further below.

3.3 The cumulative collision risk assessment for Walney Extension (presented in document 10.2.29)

for herring gull found that Rhiannon and Rhyl Flats Offshore Wind Farms are situated beyond

the mean-max foraging range for this species from Morecambe Bay SPA (Thaxter et al., 2012)

and therefore were not considered further. Only part of Gwynt-y-Môr Offshore Wind Farm is

within foraging range of Morecambe Bay SPA, however the site is included here on a

precautionary basis.

Table 3: Availability of data for herring gull within the assessment documentation of ten Irish Sea

offshore wind farm sites1.

Parameter Barrow Burbo

Bank

Gwynt y

Môr

Burbo

Bank

Extension

North

Hoyle Ormonde

Walney

I and II

West of

Duddon

Sands

Tier N/A N/A N/A 4 N/A N/A N/A N/A

Abundance/Count Y Y Y Y N N Y Y

Population

estimate/density N N N Y N Y Y N

Flight height data N N Y Y N Y Y Y

Band model N/A N/A N/A Band,

2012 N/A

Band,

2007 N/A N/A

Avoidance rate

(%) N/A N/A N/A 98 N/A 95-99.99 N/A N/A

Collision risk

identified N/A N/A N/A Y N/A N N/A N/A

3.4 Investigation of the assessments of Walney I and II (Tier 1), West of Duddon Sands (Tier 2) and

Ormonde (Tier 1) Offshore Wind Farms provides the opportunity to provide qualitative

contextual analysis to inform the EIA conclusions. Walney I and II reported a mean of just 13.8

herring gulls per survey during the breeding season (corrected for distance and survey

1 Y = Yes, N = No, N/A = not available



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coverage) over the entire study area. The observation that the majority of herring gulls were

present below PCH (RPS, 2006a) further supports the view that collision risk is negligible at this

project. The West of Duddon Sands assessment (RPS, 2006b) reports the same results found for

Walney I and II as these sites were included in the same study area covered in the baseline

surveys.

3.5 The assessment for Ormonde Offshore Wind Farm (Tier 1) makes drawing conclusions on likely

collision rates difficult (Ecology Consulting, 2005). Although it is possible to derive a collision risk

estimate for the whole year from the graphs presented it is difficult to determine the number of

collisions during the breeding season. However, it is clear that herring gulls were scarce during

the breeding season and virtually absent during June and July 2004 boat surveys, with small

numbers recorded in May and August. Furthermore, most herring gulls were recorded outside

of a 2 km buffer of the project site. The assessment concludes that it would require an unlikely

avoidance rate of 82% in order to breach a threshold for a significant effect. Collision effects on

herring gull at Ormonde were therefore considered negligible at all realistic avoidance rates.

3.6 In summary, for herring gull the following conclusions are made with respect to the cumulative

collision assessment:

Few empirical data on collision rates exist for projects within foraging range of Morecambe

Bay SPA.

Quantitative data from Walney Extension, Burbo Extension and Ormonde with qualitative

data from other projects.

Although the availability / confidence in the full dataset can be considered to be low-

moderate, a qualitative analysis of three additional sites provides appropriate evidence to

support the conclusions of the EIA and HRA.

Appropriate data are available from one Tier 1 project (Ormonde) and one Tier 4 project

(Burbo Bank Extension). These are projects for which environmental characterisation data

is available, although interpretation is required for the Ormonde assessment

Lesser black-backed gull

3.7 There are three SPAs of concern in relation to the cumulative collision risk for lesser black-

backed gull. Bowland Fells SPA, Morecambe Bay SPA and the Ribble & Alt Estuaries SPA are all

within foraging range of the Project site. As such, every wind farm site within the foraging

range of lesser black-backed gull from these three SPAs is included in the cumulative

assessment.

3.8 Table 4 presents the availability of lesser black-backed gull collision data from assessments of

Irish Sea wind farms. Availability is similar to herring gull, with the exception of Walney I and II

and West of Duddon Sands which do specifically model this species. Collision risk estimates are

therefore available for Rhiannon (Tier 5), Burbo Bank Extension (Tier 4), Walney I and II (Tier 1)

and West of Duddon Sands (Tier 2), with additional information available for Ormonde (Tier 1)

and within the Appropriate Assessment for Gwynt y Môr (Tier 2) (BERR, 2008) which assesses

the cumulative collision effect on the species incorporating data from Burbo Bank, North Hoyle

and Rhyl Flats (all Tier 1). However, no collision risk data are presented in the individual

assessments produced for Burbo Bank, Rhyl Flats, North Hoyle or Gwynt-y-Môr.



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3.9 Annex B.7.E of the Walney Extension Environmental Statement (document reference 10.2.29)

makes a quantitative assessment of lesser black-backed gull collision risk using apportioned2

collision effects for Ormonde, Rhiannon, Walney I and II, Burbo Bank Extension and West of

Duddon Sands.

Table 4: Availability of data for lesser black-backed gull within assessment documentation of ten

Irish Sea offshore wind farm sites.

Parameter Barrow Burbo

Bank

Burbo

Bank

Extension

Gwynt

y Môr

Irish Sea

Zone

(Rhiannon)

North

Hoyle Ormonde

Rhyl

Flats

Walney

I and II

West of

Duddon

Sands

Tier N/A N/A 4 N/A 5 N/A 1 N/A 1 2

Abundance/Count Y Y Y Y Y N N Y Y Y

Population

estimate/density N N Y N Y N Y N Y N

Flight height data N N Y Y Y N Y N Y Y

Band model N/A N/A Band,

2012 N/A Band, 2011 N/A

Band,

2007 N/A

Band,

2007

Band,

2000

Avoidance rate

(%) N/A N/A 98 N/A N N/A 95-99.99 N/A

95-

99.99

95-

99.99

Collision risk N/A N/A Y N/A Y N/A Y N/A Y Y

Accuracy of CRM assessments

3.10 In order to accurately inform cumulative assessment of collision risk to lesser black-backed gull

confidence in all data should be assessed. As detailed above, assessments of collision risk in the

assessments of a number of wind farms within the foraging range of lesser black-backed gull

from those SPAs identified above were undertaken using differing analytical methods.

Apportioning techniques developed in consultation with Natural England make the assumption

that an established baseline has been collected and therefore it is deemed appropriate that the

background baseline data is collected from a contemporaneous time period. Population

changes in large gull species have been significant within the Irish Sea in the last two decades,

therefore it is likely that similar trends have occurred in the at sea density of these species. This

section provides an analysis and interpretation of collision risk data from these sites to provide

a more accurate representation of cumulative collision risk within the Irish Sea including an

evaluation of:

Modelled and consented turbine numbers; and

Changes associated with the relationship between contemporaneous colony sizes and CRM

outputs

3.11 Collision risk model (CRM) estimates sourced from planning application documents for other

wind farm sites were used in the cumulative assessment presented in Annex B.7.E (document

reference 10.2.29) without further modification. These collision values were based on models

2 See NIRAS Consulting (2013b) for a description of the SPA apportioning methodology



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using the worst case turbine array scenario which for bird collision risk would typically be those

design envelope (Rochdale Envelope) scenarios involving the greatest rotor swept area.

3.12 Modelling outputs and the scenarios used to inform them are available for West of Duddon

Sands (RPS, 2006a) and Walney I and II (RPS, 2006b). The scenarios used in modelling for both

sites are notably different to the arrays that have actually been constructed, in both cases far

fewer turbines were constructed than had originally been proposed (and assessed in their

respective Environmental Statements). Consequently, the predicted collision risk estimates of

these projects are likely to be significant overestimates and, in reality, the rates actually

occurring will be lower than those used in the assessment detailed in Annex B.7.E.

3.13 Table 5 presents the number of turbines used in the CRM presented in the application

documents for West of Duddon Sands and Walney I and II, and that which was subsequently

constructed. Information indicates that the 3.6 MW Siemens turbine was used in both the

modelling process and subsequently then installed at both sites.

3.14 It is assumed that a reduction in turbines will translate into a corresponding reduction in

collisions. To investigate the relationship between the number of turbines and collision risk

estimates in the Band (2012) collision risk model, experimental numbers of turbines were

entered into the model. This indicated a direct linear relationship between the number of

turbines and the collision estimates produced (i.e. if turbine number doubles, collision risk also

doubles). Therefore, for the purposes of the cumulative assessment the predicted collision rates

for other wind farms have been corrected to take account of any differences in the number of

turbines proposed (and on which collision rate predictions were based) and the final build. The

correction factors used are as shown in Table 5.

Table 5: Walney I & II and West of Duddon Sands modelled and constructed turbine scenarios

and the resulting correction factor to be applied to cumulative assessment.

Specification Walney I & II West of Duddon Sands

No. of turbines used in CRM

152 139

No. of turbines constructed 102 108

Correction factor -32.9% -22.3%

3.15 The reduction in the number of turbines has previously been accepted by Natural England, as

part of the planning application for Burbo Bank Extension, as an appropriate method to

determine the cumulative impact of collision on lesser black-backed gull.

Contemporaneous colony size relationship with CRM outputs

3.16 Surveys for several projects considered cumulatively were undertaken much earlier than those

at Walney Extension. At the time of those surveys, the size of the population of lesser black-

backed gull and their distribution were different to those now and at the time that the baseline

surveys for Walney Extension were undertaken. These differences will have influenced the

predicted collision rates previously undertaken as it is assumed that the observed density of

gulls at sea will be related to the size of the breeding population.



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3.17 Any correction factor implemented to account for these changes requires assumptions in the

relationship between colony size and at sea density which cannot be comprehensively tested.

However, the changes in population for Bowland Fells SPA and Morecambe Bay SPA since the

surveys were undertaken to inform Walney I and II, West of Duddon Sands (2005) and Ormonde

(2004) have been dramatic (Table 6) and some attempt must be made to account for these

population changes. Therefore, in the absence of any other information, it is assumed that any

change in colony size translates, directly, into a change in collision risk.

Table 6: Lesser black-backed gull colony population size change since surveys at Walney I & II,

West of Duddon Sands, and Ormonde wind farms

Wind farm

Year

relevant to

site-specific

surveys

SPA Contemporaneous

colony size

Current

colony size

(individuals)

Change (%)

Walney I & II

and

West of

Duddon Sands

2005 Morecambe Bay 23,420 16,260 -30.6%

Bowland Fells 16,525 10,937 -33.8%

Ribble & Alt

Estuaries 6,696 6,6963 0

Ormonde 2004 Morecambe Bay 24,400 16,260 -33.36

Bowland Fells 15,483 10,937 -29.46

Ribble & Alt

Estuaries 6,696 6,6964 NC

3.18 The percentage changes presented here can be applied to collision risk estimates once the

overall collision risk estimate has been apportioned to individual SPA colonies. The cumulative

SPA apportioning assessment for lesser black-backed gull is presented in NIRAS Consulting

(2013b).

3.19 The Appropriate Assessment of Gwynt y Môr (BERR, 2008) updates the findings given in the ES

and provides a cumulative collision assessment for the site plus Burbo Bank, North Hoyle and

Rhyl Flats. An avoidance rate of 98% is not given although this can be calculated from the given

avoidance rates (e.g. 97%). A total of 17 lesser black-backed gulls per annum are predicted to

collide with turbine rotors (or 34 including unidentified black-backed gulls). This total does not

take into account any apportioning to source colony and is presumably based on Band (2007).

3.20 In summary, for lesser black-backed gull the following conclusions are made with respect to the

cumulative collision assessment:

Collision data exists for six projects within foraging range Morecambe Bay SPA. These are

all considered within the EIA and Habitats Regulation Assessment (HRA) for Walney

Extension.

An assessment of the cumulative effects of these sites on the Morecambe Bay SPA is given

in NIRAS Consulting (2013b). 3 Proposed colony size post-cull

4 Proposed colony size post-cull



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No collision data (or population estimates) are available in the assessments for the Burbo

Bank, North Hoyle, Rhyl Flats (all Tier 1 projects) or Gwynt y Môr (Tier 2) wind farms.

However, a cumulative collision assessment for these sites is presented in BERR (2008).

Data is available from two Tier 1 projects, one Tier 2 project, one Tier 4 project and one

Tier 5 project. Environmental characterisation data is available from projects in Tiers 1-4

although a degree of interpretation is required for those projects in Tier 1. Data for

Rhiannon is subject to change and as such confidence in these data is lower.

Further data could be incorporated from the Appropriate Assessment (BERR, 2008) which

contains data for four Tier 1 projects although interpretation is again required to acquire

usable collision risk estimates.

Table 7 presents the collision risk estimates that will be taken forward for use in the revised

cumulative assessment of collision risk for lesser black-backed gull at those offshore wind farms

within foraging range of the three SPAs within the Irish Sea.



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Table 7: Collision risk estimates for lesser black-backed gull at 98% avoidance for those projects included within cumulative impact assessment

Ormonde Walney I & II

West of

Duddon

Sands

Burbo

Bank

Extension

Irish Sea

Zone

(Rhiannon)

Gwynt-y-Môr North Hoyle Rhyl Flats Burbo Bank

Tier 1 1 2 4 5 2 1 1 1

Applicability of data

Interpreted

from

assessment

Interpreted

from

assessment

Interpreted

from

assessment

-

Liable to

significant

change

Interpretation

required

Interpretation

required

Interpretation

required

Interpretation

required

Collision risk (98%

avoidance rate) 48 87 80 123 132 215 35 35 85

5 The Gwynt-y-Môr Appropriate Assessment includes collision risk estimates for lesser black-backed gull and lesser black-backed gull combined with black-backed gull sp.. The

estimates presented here are for lesser black-backed gull only with data requiring further analysis if a proportion of black-backed gull sp. is to be included. However, this would reduce confidence in these data.



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4 Cumulative displacement assessment data

4.1 The inclusion of species in the assessment of displacement effects within the Walney Extension

Offshore Ornithology ES chapter was informed by the sensitivity of a species to displacement

as presented in Maclean et al. (2009) and Furness and Wade (2012). Based on this evidence

red-throated diver, Manx shearwater, guillemot and razorbill were included in the assessment

of displacement effects for both Walney Extension alone and cumulatively with other offshore

wind farms.

4.2 The displacement analysis at Walney Extension included only those wind farms in the north-

east of the Irish Sea. Therefore, if data were available the analysis would include Barrow,

Ormonde, Walney I and II, Walney Extension and West of Duddon Sands. However, the

projects considered cumulatively for Manx shearwater are informed by advice from Natural

Resources Wales (NRW) for the ornithological assessment at Burbo Bank Extension.

Manx shearwater

4.3 The cumulative displacement analysis presented within the Offshore Ornithology ES chapter

(document reference 10.1.13) has been superseded by an updated analysis incorporating data

from Burbo Bank Extension and Atlantic Array (both Tier 4 projects) (NIRAS Consulting, 2013c).

This analysis follows the advice given on the ornithological assessment for Burbo Bank

Extension by NRW (PINS project reference EN010026). Breeding period population estimates

have been combined from each of the three projects and results apportioned to relevant SPA

populations. A displacement rate of 30% and mortality rate of 10% were proposed, which leads

to a conclusion of no significant impacts predicted for any of the SPAs included within the

analysis (Skokholm and Skomer SPA, Aberdaron Coast and Bardsey Island SPA, and Copeland

Island SPA).

Guillemot

4.4 Table 8 presents the availability of data to inform a displacement analysis for guillemot in the

assessments of Irish Sea wind farms. Displacement analysis as outlined by Natural England and

JNCC (2012) is not available in any of the four other Irish sea wind farm sites considered in this

cumulative assessment although population data are available from Ormonde, Walney I and II

(both Tier 1) and West of Duddon Sands (Tier 2) which has enabled a qualitative approach

within these assessments.

4.5 The cumulative displacement analysis presented in the Walney Extension Offshore Ornithology

ES chapter (document reference 10.1.13) concludes that due to the large extent of habitat

available to guillemot within the Irish Sea any cumulative displacement effects will not be

significant in EIA terms.



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Table 8: Availability of data for guillemot within assessment documentation of Irish Sea offshore

wind farm sites.

Parameter Barrow Ormonde Walney I and II West of Duddon

Sands

Tier 1 1 1 2

Abundance/Count Y N Y Y

Population

estimate/density N Y N Y

Displacement

analysis N N N N

Geographic scale N/A N/A N/A N/A

4.6 The assessment for Barrow Offshore Wind Farm (Tier 1) only details the counts of guillemot

recorded in aerial and boat-based surveys (Warwick Energy, 2002) with no quantitative or

qualitative assessment on the effects of displacement. Few auks were however recorded in the

wind farm area during aerial surveys although auks were more abundant in the wider aerial

survey area.

4.7 Although no quantification of displacement is presented in the Ormonde Offshore Wind Farm

(Tier 1) assessment for guillemot, monthly population estimates from the aerial survey area

and the wind farm plus a 2 km buffer area are presented graphically. Guillemot were

distributed evenly across the boat-based survey although in aerial surveys distribution was

centred in areas further offshore. Guillemot were however, recorded in the wind farm area in

both boat-based and aerial surveys. The assessment presents a qualitative summary of

displacement suggesting an impact on razorbill. The assessment presents a qualitative

summary of displacement suggesting an impact of low significance for guillemot.

4.8 Auk species were widely distributed across the aerial survey area used in the Walney I and II

Offshore Wind Farm (Tier 1) assessment with many auks recorded within the wind farm area. A

detailed qualitative assessment is carried out for guillemot and suggests that the magnitude of

any displacement impacts if low for this species.

4.9 Population estimates from boat-based surveys and raw counts from aerial surveys are

presented for guillemot within the assessment for West of Duddon Sands (Tier 2). Observations

of auks indicate a wide distribution across the boat-based study area with many observations

within the wind farm area. A qualitative displacement assessment concludes that any

displacement impacts are of low magnitude.

Razorbill

4.10 Table 9 presents the availability of data to inform a displacement analysis for razorbill in the

assessments of Irish Sea wind farms. Displacement analysis as outlined by Natural England and

JNCC (2012) is not available in any of the four other Irish sea wind farm sites considered in this

cumulative assessment although population estimates are available from Ormonde, Walney I

and II (both Tier 1) and West of Duddon Sands (Tier 2) which has enabled a qualitative

approach within these assessments.



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4.11 The cumulative displacement analysis presented in the Walney Extension Offshore Ornithology

ES chapter (document reference 10.1.13) concludes that due to the large extent of habitat

available to razorbill within the Irish Sea any cumulative displacement effects will not be

significant in EIA terms.

Table 9: Availability of data for razorbill within assessment documentation of Irish Sea offshore

wind farm sites.


Sands

Tier 1 1 1 2


Population


Displacement

analysis N N N N


4.12 The assessment for Barrow Offshore Wind Farm (Tier 1) only details the counts of razorbill in

aerial and boat-based surveys (Warwick Energy, 2002) with no quantitative or qualitative

assessment on the effects of displacement. Few auks were recorded in the wind farm area

during aerial surveys although auks were more abundant in the wider aerial survey area.


(Tier 1) assessment for razorbill, monthly population estimates from the aerial survey area and

the wind farm plus a 2 km buffer area are presented graphically. Razorbill were distributed

evenly across the boat-based survey area although few were present in the wind farm area.

The assessment presents a qualitative summary of displacement suggesting an impact on

razorbill. The assessment presents a qualitative summary of displacement suggesting an impact

of low significance for razorbill.

4.14 Auk species were widely distributed across the aerial survey area used in the Walney I and II

Offshore Wind Farm (Tier 1) assessment with many auks recorded within the wind farm area. A

qualitative assessment is carried out for razorbill and suggests that the magnitude of any

displacement impacts is low for this species.


presented for razorbill within the assessment for West of Duddon Sands (Tier 2). Although no

species-specific distribution is presented for razorbill observations of unidentified auks are

presented and indicate a wide distribution across the boat-based study area with many

observations within the wind farm area. A qualitative displacement assessment concludes that

any displacement impacts are of low magnitude.

Red-throated diver

4.16 Table 10 presents the availability of data to inform a displacement analysis for red-throated

diver in the assessments of Irish Sea wind farms. Displacement analysis as outlined by Natural

England and JNCC (2012) is not available in any of the four other Irish sea wind farm sites



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considered in this cumulative assessment although population estimates are available from

Ormonde, Walney I and II (both Tier 1) and West of Duddon Sands (Tier 2) which has enabled a

qualitative approach within these assessments.

4.17 As with guillemot and razorbill, the potential cumulative displacement impacts on red-throated

diver as a result of those wind farms outlined above were considered to be not significant in

EIA terms.

Table 10: Availability of data for red-throated diver within assessment documentation of Irish Sea

offshore wind farm sites.


Sands

Tier 1 1 1 2


Population


Displacement

analysis N N N N


4.18 The assessment for Barrow Offshore Wind Farm (Tier 1) only details the counts of red-throated

diver in aerial and boat-based surveys (Warwick Energy, 2002) with no quantitative or

qualitative assessment on the effects of displacement. Low numbers of red-throated diver

were recorded in aerial surveys undertaken for the assessment of Barrow offshore wind farm

with the assessment suggesting the wind farm site is not an important area for bird species.


(Tier 1) assessment for red-throated diver, monthly population estimates from the aerial

survey area and the wind farm plus a 2 km buffer area are presented graphically. Very few

divers were recorded in the wind farm plus a 2 km buffer area with the majority observed

further south within Liverpool Bay SPA. The assessment presents a qualitative summary of

displacement suggesting an impact of low significance for red-throated diver.

4.20 Raw count data for Walney I and II Offshore Wind Farm (Tier 1) indicate that diver activity

within the wind farm area plus a 2 km buffer is low. No displacement analysis is conducted for

red-throated diver although a qualitative assessment suggests that the magnitude of any

displacement impacts are negligible on this species.


presented for razorbill within the assessment for West of Duddon Sands (Tier 2). A very low

level of diver activity was recorded within the wind farm plus a 1 km buffer and a qualitative

analysis of displacement effects on the species indicates this impact is believed to be of

negligible magnitude.



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5 Conclusion

5.1 This paper considers the data used to inform the cumulative collision assessments for herring

gull and lesser black-backed gull. Confidence in the source data used for lesser black-backed

gull is considered to be high. Confidence in herring gull data is considered to be low-moderate

due to the absence of collision estimates from projects within the foraging range of

Morecambe Bay SPA. However, a qualitative analysis of the data presented strongly suggests

that there is a negligible potential for a significant effect on this species.

5.2 Data relating to collision risk for lesser black-backed gull is available from a number of Tier 1-3

Projects (Ormonde, Walney I &II and West of Duddon Sands) although a degree of

interpretation is required in order to provide a consistent metric upon which to base a

cumulative assessment. Data from one Tier 4 project (Burbo Bank Extension) is available and

the quality of this data is considered to be high, as the analytical methodology is consistent

with that undertaken at Walney Extension. Lower quality data is available for one Tier 2 project

(Gwynt-y-Môr) three Tier 1 projects (Burbo Bank, North Hoyle and Rhyl Flats) presented in the

Gwynt-y-Môr Appropriate Assessment and one Tier 5 project (Rhiannon).

5.3 Also considered in this Paper is the data used to inform the cumulative displacement

assessments for Manx shearwater, guillemot, razorbill and red-throated diver. No displacement

analyses following the guidance published by Natural England and JNCC (2012) have been

carried out in any of the additional four projects included in the cumulative assessment for

Walney Extension due to these projects having been completed before the publishing of the

guidance. However, population data presented in each of the assessments provide guidance on

the number of birds of each species utilising each wind farm area and therefore the likely

displacement effects as a result of each wind farm. Although, no analyses have been carried

out it is believed that confidence in the data is high due to the population data presented

which is relatively similar across the four additional wind farms.

5.4 Additional analyses, relating to the cumulative collision risk to lesser black-backed gull and

impacts on Manx shearwater are presented in NIRAS Consulting (2013a) and NIRAS Consulting

(2013c), respectively. Following this review the conclusions drawn for herring gull, red-throated

diver, guillemot and razorbill in Chapter 13 of the Walney Extension Environmental Statement

(document reference 10.1.13) and Annex B.7.E of the Walney Extension Environmental

Statement (document reference 10.2.29) are considered to be appropriate.



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6 References

Band, W., Madders, M., and Whitfield, D. P., 2007. Developing field and analytical methods to

assess avian collision risk at wind farms. In: de Lucas, M., Janss , G. F. E., and Ferrer, M., eds. Birds

and wind farms: risk assessment and mitigation. Madrid: Quercus.

Band, B., 2011. Using a collision risk model to assess bird collision risks for offshore windfarms.

Thetford: BTO.

Band, B., 2012. Using a collision risk model to assess bird collision risks for offshore wind farms –

with extended method. [Online]. Available at: http://www.bto.org/science/wetland-and-

marine/soss/projects (Accessed July 2013).

BERR, 2008. Appropriate Assessment with regard to Gwynt-y-Mor. Department for Business,

Enterprise & Regulatory Reform.

Centrica Energy, 2012. Irish Sea Zone: Zonal Appraisal and Planning (ZAP) Report. Chapter 13.

Ornithology. [Online]. Available at: http://www.centrica.com/celticarray/ (Accessed July 2013).

Chamberlain, D.E., Rehfisch, M.R., Fox, A.D., Desholm, M. and Anthony, S.J, 2006. The effects of

avoidance rates on bird mortality predictions made by wind turbine collision risk models. Ibis, 148,

pp. 198-202.

DECC, 2011. Record of the Appropriate Assessment for Docking Shoal Wind Farm, Race Bank Wind

Farm and Dudgeon Wind Farm. Department of Energy and Climate Change.

DONG Energy, 2013. Walney Extension Offshore Wind Farm Environmental Statement Chapter 13:

Offshore Ornithology. London: DONG Energy.

Ecology Consulting, 2005. Ormonde Proposed Offshore Wind Farm. Ornithological Impact

Assessment. Durham: Ecology Consulting.

JNCC and Natural England, 2013. JNCC and Natural England Suggested Tiers for Cumulative Impact

Assessment.

Krijgsveld, K.L., Fijn, R.C., Japink, M., van Horssen, P.W., Heunks, C., Collier, M.P., Poot, M.J.M.,

Beukers, D. and Dirksen, S., 2011. Effect studies Offshore Wind Farm Egmond aan Zee. Flux, flight

altitude and behaviour of flying birds. Culemborg: Bureau Waardenburg.

Natural England and JNCC, 2012. Joint Natural England and JNCC Interim Advice Note – Presenting

information to inform assessment of the potential magnitude and consequences of displacement of

seabirds in relation of Offshore Windfarm Developments. Peterborough: JNCC.

NIRAS Consulting, 2013a. Walney Extension Offshore Wind Farm. Clarification Note: SPA

Apportioning and PBR analysis. Cambridge: NIRAS Consulting Ltd.

NIRAS Consulting, 2013b. Walney Extension Offshore Wind Farm. Clarification Note: Collision risk

modelling Options and Potential Collision Height. Cambridge: NIRAS Consulting Ltd.

NIRAS Consulting, 2013c. Walney Extension Offshore Wind Farm. Manx Shearwater Displacement.

Cambridge: NIRAS Consulting Ltd.

Npower renewables, 2007. Gwynt y Môr Offshore Wind Farm Environmental Statement Chapter 6

The existing biological environment.

NWP Offshore Ltd., 2002. North Hoyle Offshore Wind Farm Environmental Statement Chapter 5

Assessment of Environmental Impacts. [Online]. Available at:

http://www.rwe.com/web/cms/mediablob/en/312158/data/312146/1/rwe-innogy/sites/wind-

offshore/in-operation/north-hoyle/environment/environmental-statement/chapter5.pdf (Accessed

July 2013).



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RPS, 2006a. Walney Offshore Windfarm Environmental Statement. DONG Energy.

RPS, 2006b. West of Duddon Sands Offshore Windfarm Ornithological Impact Assessment. St Ives:

RPS.

Seascape Energy Ltd., 2002. Burbo Offshore Wind Farm – Ornithology. Final Report. [Online].

Available at:

http://www.dongenergy.com/SiteCollectionDocuments/New%20Corporate/Burbo/BurboAppVol4B

Birds.pdf (Accessed 30 October 2012).

Seascape Energy Ltd., 2008. Burbo Offshore Wind Farm – Construction Phase Environmental

Monitoring Report. Warrington: Hyder Consulting Ltd.

SNH, 2010. Use of Avoidance Rates in the SNH Wind Farm Collision Risk Model. [Online]. Available

at: http://www.snh.gov.uk/docs/B721137.pdf (Accessed July 2013).

Thaxter, C.B., Lascelles, B., Sugar, K., Cook, A.S.C.P., Roos, S., Bolton, M., Langston, R.H.W. and

Burton, N.H.K., 2012. Seabird foraging ranges as a preliminary tool for identifying candidate Marine

Protected Areas. Biological Conservation, 156, pp. 53-61.

Warwick Energy, 2002. Barrow Offshore Wind Farm Environmental Impact Statement. Helsby: RSK

Environment Limited.



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7 Appendix 1 – Tiered approach for cumulative assessment

Table 11: Suggested tiers for undertaking a staged cumulative impact assessment Tier

description.

Consenting or construction stage Data availability

Tier 1 Built and operational projects should be included within the cumulative assessment where they have not been included within the environmental characterisation survey, i.e. they were not operational when baseline surveys were undertaken, and/or any residual impact may not have yet fed through to and been captured in estimates of “baseline” conditions e.g. “background” distribution or mortality rate for birds.

Pre-construction (and possibly post-construction) survey data from the built project(s) and environmental characterisation survey data from proposed project (including data analysis and interpretation within the ES for the project).

Tier 2 Tier 1 + projects under construction As Tier 1 but not including post-construction survey data

Tier 3 Tier 2 + projects that have been consented (but construction has not yet commenced)

Environmental characterisation survey data from proposed project (including data analysis and interpretation within the ES for the project) and possibly pre-construction survey data from built project.

Tier 4 Tier 3 + projects that have an application submitted to the appropriate regulatory body that have not yet been determined

Environmental characterisation survey data from proposed project (including data analysis and interpretation within the ES for the project)

Tier 5 Tier 4 + projects that the regulatory body are expecting an application to be submitted for determination (e.g. projects listed under the Planning Inspectorate programme of projects)

Possibly environmental characterisation survey data (but strong likelihood that this data will not be publicly available at this stage).

Tier 6 Tier 5 + projects that have been identified in relevant strategic plans or programmes (e.g. projects identified in Round 3 wind farm zone appraisal and planning (ZAP) documents)

Historic survey data collected for other purposes/by other projects or industries or at a strategic level.

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