East Anglia ONE Offshore Windfarm
April, 2016
Pre-construction 5810000
Site boundary Transect
Post-construction
5800000
5790000
5780000
5770000
455000 460000 465000 470000 475000 UTM Easting
455000 460000 465000 470000 475000 UTM Easting
Figure 2. Illustration of guillemot distributions (red dots) in January (at 6.01 birds/km2) simulated in a pre-construction year (left) and post-construction year (right) with 50% of birds within the wind farm displaced to locations outside the wind farm but within the survey area (i.e. no change in overall abundance). Note analysis was only conducted using birds located within the survey transects.
2.2 Macro-avoidance analysis 11.
To estimate the distance over which macro-avoidance is detectable (that is avoidance of the wind farm as a whole) the following method was developed. The input data were the same as used for spatial modelling (i.e. birds recorded within the simulated transects), using a design with transects spaced at 1.4km (further explanation for this spacing is provided in the results). However, data for each month were combined into a single dataset for analysis, on the assumption that bird responses to the wind farm would be consistent across a winter period and this gives a larger sample size for analysis. Furthermore, as this analysis was focussed on gannet behaviour on migration the assumption of consistency of response was considered appropriate.
12.
The density of birds recorded within the wind farm and sequential 500m wide buffers from the wind farm up to 2km (i.e. 0- 500m, 0-1000m, 0m-1500m, 0m-2000m) was calculated for both the simulated ‘before’ data and ‘after’ data (i.e. impacted). The after data were generated with the application of a displacement effect of 99% displacement within a pre-selected distance (500, 1000, 1500, 2000m). Separate simulations were conducted for each displacement distance. The before and after density estimates provided the baseline values for comparison with 1,000 bootstrapped replicated values. The key step, prior to each bootstrap replicate, was relocation of the wind farm polygon and buffers by up to 2000m in both the x and y coordinates (using uniform random numbers for each coordinate). In other words, the entire wind farm was randomly offset and the density of birds in the relocated wind farm and buffer strips recalculated.
13.
The aim of the analysis was to compare the densities calculated for the actual wind farm and buffer strips (using both before and after data) with those generated for the bootstrapped wind farms, thus enabling identification of the distance over which macro-avoidance behaviour was occurring. As the key species of interest with regards macro-avoidance of wind farms is
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UTM Northing
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