East Anglia ONE Offshore Windfarm
April, 2016
18.
Following review of the initial results, a second run of simulations was conducted for gannet and kittiwake (as small reductions in guillemot abundance were detected using the least intensive survey design no further simulations were conducted for this species). The model parameters were as follows:
Displacement magnitude – 30% and 50%; Transect spacing – 1.4km; and, Targeted surveys – 2 per month in October and November and 1 per month in December to March.
19.
This gave a total survey number of eight per winter, but focussed on the early part of the season to coincide with the expected peak in gannet and kittiwake numbers, as seen during the baseline surveys. The results of these analyses are provided in Table 3.
Table 3. Follow-up power analysis results. Scenarios with power >0.8 (i.e. >80% detection of effect) are highlighted in underlined bold.
Species Gannet Kittiwake
Percentage displaced
30 50 30 50
3.2 Macro-avoidance analysis 20.
Simulations were based on the survey design identified in Table 3 which generated sufficient power to detect gannet displacement (1.4km transect spacing, targeted surveys).
21.
Overlaying the density of gannets calculated for each 500m buffer from the actual wind farm onto histograms of the bootstrapped densities for 1,000 randomly relocated wind farms indicated that there was no underlying distribution (Figure 3). This was to be expected, given that the gannet locations generated for the before period were uniformly distributed across the survey region.
Transect spacing
1.4 Area surveyed (%) No. surveys / month Power 17.3
Targeted – Oct x2, Nov x2, Dec x1, Jan x1, Feb x1, Mar x1
0.53 0.85 0.7
0.88
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