East Anglia ONE Offshore Windfarm
April, 2016
Displacement distance - 2000 Density 0-500m Density 500-1000m
0.0 0.2 0.4 0.6 Density (birds/km2)
Density 1000-1500m
0.0 0.2 0.4 0.6 Density (birds/km2)
Density 1500-2000m
0.0 0.2 0.4 0.6 Density (birds/km2)
0.0 0.2 0.4 0.6 0.8 Density (birds/km2)
Figure 7. Histograms of gannet density within 500m buffers around 1,000 randomly relocated wind farms, with the density within the buffers around the actual wind farm indicated by red lines, data generated with 99% of birds displaced within 2000m of the actual wind farm.
4 Conclusions 4.1 Power analysis 25.
Using simulated bird distributions derived from baseline surveys of the East Anglia ONE site and proposed monitoring designs the probability of detecting displacement effects has been estimated for gannet, kittiwake and guillemot. Not surprisingly, the probability (or power) was lowest for the least abundant species, gannet.
26.
The gannet breeding population of greatest concern in relation to East Anglia ONE is that at Flamborough and Filey Coast pSPA. The timing of the autumn peak in numbers recorded on the wind farm is consistent with southward migration of individuals from this colony (but also from the much larger colonies further north such as Bass Rock), highlighting the value of focussing survey effort during this period (Garthe et al. 2012, Furness 2015). In order to reach a power of 80% for gannet, survey frequency was doubled during the period when this species is expected to pass through the region on migration. This design was found to yield sufficient power to detect a 50% decline in this species within the wind farm area following construction of the wind farm.
27.
Guillemot abundance peaked later in the winter (December – February) and was sufficiently high that a single survey per month across this period would be expected to provide an adequate sample size. Kittiwake peaked in November and December, therefore the additional survey effort for gannet in November would also be expected to improve the ability to detect effects on kittiwake.
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Frequency 0 50 150
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