2011-2013, Ecology Consulting, Kentish Flats Offshore Wind Farm, Diver Surveys 2011-12 and 2012-13 series https://portal.medin.org.uk/portal/start.php?tpc=015_1318eb80-fbca-470f-8d60-dd07c6916d24 Surveys of the distribution and abundance of red-throated divers at the Kentish Flats wind farm during the pre-construction, construction and post-construction phases of the wind farm have been undertaken over 10 years prior to 2011-12 and have been reported previously. This report presents an analysis of new data sets from surveys completed at Kentish Flats during 2011-12 and 2012-13. The original statistical analysis carried out for the monitoring conducted under the FEPA licence of the effects of the Kentish Flats wind farm on bird populations utilised a BACI (before-after-control-impact) approach. However it was acknowledged in the monitoring reports that this was of relatively low power which meant that no statistically significant effect was identified although a qualitative assessment suggested an avoidance of the site by divers. Evidence has been found of displacement of divers from within the wind farm site, with this effect apparent in all seven years of post-construction monitoring. The 2011-12 and 2012-13 results have confirmed a much reduced diver density within the wind farm, and provided further data to inform the estimation of the magnitude of that displacement. The precise magnitude of the effect is dependent on exactly which comparisons are made and whether account is taken on the variability in diver populations in the wider survey area. However, the analysis presented here suggests a displacement of between 89% (comparing recent densities within and outside the wind farm) and 94% (comparing with previous pre-construction densities). Outside the wind farm the results are less clear. The area within 3km of the wind farm has consistently held lower densities of divers than during the pre-construction period, but there has also been a decline in divers in the survey area generally (and the extent of the control area is insufficient to enable a full BACI analysis to be undertaken, particularly in light of the high variability in numbers in that area between years). The new data from a wider survey area has enabled the geographic extent of the diver displacement to be investigated further. This new analysis suggests that comparison with the pre-construction baseline has over-estimated the displacement effect in these zones (which might be better explained by spatial and/or temporal changes in the wider diver population). The gradient analysis showed no evidence of diver displacement beyond 1km from the wind farm in 2011-12 and in 2012-13. There was some suggestion from the 2008-09 data in particular that the magnitude of the diver displacement may be decreasing through time; divers may be habituating to the presence of the wind turbines. The 2011-12 and 2012-13 data do not however provide support to such a hypothesis of habituation, with no records at all within the wind farm in 2012-13. As noted in the previous reports, the biological importance of diver displacement is not yet clear and needs to be addressed with reference to the context of the wider diver population within the Outer Thames Estuary. It is also important to recognise that the results for this site may not be directly applicable to other wind farm sites given the Kentish Flats wind farm’s relatively small number of turbines and footprint size, and its relatively low importance for divers. It is possible, for example, that divers using a site of greater importance/attractiveness to them may be less likely to be affected by disturbance than those at Kentish Flats. 20140501