Seabirds & offshore wind farms: Monitoring results 2008

In 2008, n.v. C-Power started up the construction of the first offshore wind farm at the Belgian Part of the North Sea (BPNS). This wind farm will be located on the shallows of the Thorntonbank, about fifteen nautical miles offshore. At the time of writing six windmills are erected of which two are in operation, but in the near future the wind farm will comprise of 60 turbines in total, each with a capacity of 5MW. Following the reference study (Vanermen et al. 2006), this report presents an update of the reference situation and the results of the year-1 monitoring of the avifauna at the Thorntonbank. To assess possible impacts on seabirds, we implement a methodology based on the BACI-principles. Hence the before-situation (2005-2007) is compared with the situation in 2008, during which the first construction works took place. Possible changes in avian densities are put in perspective by performing the same before-after comparison in a control area (see Vanermen et al. 2006).Based on intensive monitoring in 2005-2007, it seems that Annex I species Little gull, Sandwich tern and Common tern all occur in increased densities at the Thorntonbank wind farm site. On the other hand, Vanermen et al. (2006) overestimated the importance of the area to Great skuas. Next to this, we set up a ranking of seabird species according to their suitability for monitoring. Auks seems the most suitable species, followed by Little gull, Sandwich tern and Common tern. Hence, future monitoring will focus on these 5 species. A comparison of the monitoring results of the reference period (2005-2007) and the first construction year do not yet show clear effects.Meanwhile, n.v. Belwind has received their license for the construction and exploitation of a wind farm comprising of 110 3MW turbines on the Blighbank, 24 nautical miles offshore. Analogous to Vanermen et al. (2006), the Research Institute for Nature and Forest (INBO) carried out a reference study on the ornithological importance of the wind farm site at the BB, and selected a suitable control area.Based on intensive seabird monitoring, we know that the area is characterised by a typical offshore and relatively species-poor bird community. Black-legged kittiwakes and Common guillemots occur in high densities, while there are signs of increased densities of rarer species like Little gull and Great skua. As a control area, we selected an area including the rest of the Blighbank and the Oosthinderbank.Finally, we made a preliminary estimation of the number of collision victims at the future wind farm site at the Thorntonbank, based on flux counts, flying height observations and model calculations. Northern gannets and especially large gulls are most at risk. Meanwhile, this was an inventory of the needed (and lacking) parameters. It appears that radar research will be indispensable for determining data on bird movements, flying heights as well as avoidance behaviour