Birds in southern Öresund in relation to the wind farm at ... - Vattenfall

the windfarm area but fishing activity was low after the establishment of the windfarm as it
was before.
Taken together our studies of staging and wintering waterbirds in the Lillgrund area do not
show any larger changes in the distribution or their utilization of the area that could be related
to the construction of the windfarm. Some local effects were found for the sea ducks which
showed lower densities and some avoidance of the windfarm area, but the total area affected
is very small compared to the extent of the feeding areas for these species in southern
Öresund. Moreover, some signs of habituation to the wind farm was seen at least for the
Eider, and maybe also for the two other species (Long-tailed Duck and Red-breasted
Merganser). If this should be a general pattern, it means that local effects may arise in the first
years after construction of a wind farm but that after some time the birds will start using the
area again.
Even if there are few other studies of the impact of offshore wind farms on marine birds (cf.
reviews by Drewitt & Langston 2006, Fox et al. 2006) the number of such are increasing as
more farm are constructed in this habitat.
In Sweden, there are two small offshore wind farms in the Kalmarsund region (Pettersson
2005), but the studies here were concentrated to the effect of the wind farms on migrating
birds, especially the Eider and did not address staging and wintering waterbirds with pre- and
post-construction studies.
In Denmark, large scale impact assessment studies have been published for the two large
offshore wind farms, Nysted and Horns Rev (Dong Energy 2006, Petersen et al. 2006,
Petersen & Fox 2007 and further references in these reports) and also for the smaller farm at
Tunö Knob (Guillemette et al. 1997, 1999, Guillemette & Larsen 2002). In general the Danish
studies showed avoidance of the offshore wind farms when comparing pre - and postconstruction
aerial surveys. However, the responses in the Danish wind farms as in the case of
Lillgrund were rather species specific. The species occurring at the two larger Danish sites
were also, at large, different from that at Lillgrund.
At both Lillgrund and Nysted, Long-tailed Ducks occur in smaller numbers, both sites being
situated at the margin of winter distribution of the species. A clear avoidance behavior of
Long-tailed Ducks was recorded at both sites. Numbers affected were however small in both
cases and the effect is of no importance for the general distribution and abundance in the area.
At Horns Rev, Common Scoters first seemed to avoid the wind farm but Petersen & Fox
(2007) discussed the possibility of a habituation effect. It was however not possible to rule out
possible effects of the food situation for the Scoters, meaning that also the initial apparent
avoidance may in fact have been caused by other factors than the wind farm itself. Avoidance
of Common Scoters and Eiders was also indicated in the studies at Tunö Knob, but here an
increase in Eiders was noticed later during post-construction, this increase possibly being due
to changes in the food resources (Guillemette et al. 1997, 1999).
The seabird community in the North Sea area where Horns Rev is situated is markedly
different from the Öresund and also the Baltic proper. In the Horns Rev area divers was an
important component, these birds showing a more or less total avoidance of the windfarm
area. Avoidance behavior was also noted for Guillemots and Razorbills at Horns Rev
(Petersen et al 2006). Other recent studies in the North sea show a rather strong avoidance
effect for Red-throated Divers at a wind farm at Kentish Flats, UK but results both from that
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