East Anglia ONE Offshore Windfarm


April, 2016


1 Introduction 1.


This note provides a summary of the methods and results of preliminary power analyses conducted to help guide the design of aerial surveys for the East Anglia ONE offshore wind farm (hereafter referred to as the wind farm). The wind farm is located approximately 45km off the East Anglia coast at its closest point. The surveys to which this document refers will ultimately discharge the conditions set out in the East Anglia ONE generation Deemed Marine Licence related to the requirement to undertake ornithological monitoring.


2.


Following discussions between East Anglia Offshore Limited (EAOL) , Natural England (NE) and the Marine Management Organisation (MMO) on the subject of ornithological monitoring it was agreed that the key monitoring period for the offshore site was the nonbreeding season (defined as October to March inclusive), covering migration of seabirds to and from their breeding colonies (primarily gannet and kittiwake) and over-wintering distributions of guillemot and razorbill. The key concerns for these species relate to collision risk (gannet and kittiwake) and displacement (the auks). It was also agreed that the most suitable method for collecting data on the distributions of these species was by means of digital aerial surveys.


3.


The specific survey requirements set out in correspondence from the MMO (18th December 2015) which are addressed in the current document are:


 The methodology will be designed to identify if auk locations are influenced by the presence of the East Anglia ONE wind farm;


 Alignment of transects will be approximately east-west; and,  Survey effort (number of surveys to be carried out per month) and percentage coverage, as informed by power analysis, will be agreed with the MMO.


4.


It should be noted that there were additional requirements in relation to collecting flight height data, in particular for gannet and kittiwake. This requirement has been accepted by EAOL and these data will be collected, however this document is focussed on the identification of methods for collecting robust spatial distribution data and therefore this aspect is not consider here.


5.


Methods for analysing seabird location data obtained by ship or aerial survey methods have been developed which enable robust estimation of the magnitude and statistical significance of displacement effects (Mackenzie et al. 2013). These methods were developed to perform comparison of data collected before and after wind farm construction, however they are equally suitable for analysing simulated data to test for the power to detect changes in distributions of a given magnitude (i.e. power analysis). This document provides a summary of the methods used to simulate bird distributions before and after wind farm construction, overlay an aerial survey design and analyse the data. By repeating this process the power to detect changes was estimated as the proportion of simulations in which the known effect was correctly detected. For the purposes of the current analysis, two effects are considered; displacement and macro-avoidance. Macro-avoidance is defined here as behaviour which causes birds to alter their flight paths to avoid flying through the wind farm, with almost all individuals responding in this manner. In contrast, displacement has been treated as a less absolute behavioural response with smaller proportions of the population (e.g. 50%) avoiding the wind farm.


6.


The results presented here are intended to be used in discussion with the MMO and NE in order to agree the survey design parameters to enable East Anglia ONE Limited to procure a survey contractor to undertake pre-construction surveys. Although not presented in any detail within this document, EAOL will also ensure, as part of the aerial survey procurement process, that the aerial digital methods which are proposed will also enable flight height data to be collected in order to assess the potential influence of the wind farm on gannet flight heights.


2 Methods 7.


Two complementary methods were used to analyse the simulated data in relation to the wind farm. The first used spatial modelling techniques developed by St. Andrews University (Mackenzie et al. 2013) and the second was developed to assess macro-avoidance distances from the wind farm.


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