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

Results
Staging and wintering birds
In this chapter we analyze the occurrence and distribution of staging/wintering water birds in
relation to the wind farm at Lillgrund by comparing the patterns recorded before and after the
construction of the wind farm. We base the comparisons both on the boat and aerial surveys.
The total numbers of birds of all species counted at the surveys are shown in Tables A1 and
A2 in the appendix. Here we focus on the species occurring regularly at Lillgrund and which
could possibly be affected by the wind farm. Five species, (Cormorant Phalacrocorax carbo,
Long-tailed Duck Clangula hyemalis, Eider Somateria mollissima, Red-breasted merganser
Mergus serrator and Herring Gull Larus argentatus) were found regularly in the Lillgrund
area before the construction of the wind farm and will hence be in focus for this analysis.
During the boat surveys, which only cover offshore areas (Fig. 3), a total of 26 species were
recorded during the surveys (Table A1-A3 in the appendix). During the aerial surveys the
transects go from the shore to the outer limit of the study area (Fig. 5) and they will therefore
cover a number of inshore water bird species that never are found in the offshore areas (these
species will not be discussed any further here). In all 35 species were seen during the aerial
surveys (Table A4 - A9 in the appendix).
In addition to the offshore species occurring regularly at Lillgrund, two sea ducks were found
in larger numbers in the reference area south of Falsterbo: Velvet Scoter Melanitta fusca and
Common Scoter Melanitta nigra. These species were also found around Lillgrund in very
small numbers but not on a regular basis.
The Goldeneye Bucephala clangula is a diving duck that is normally found in shallow water
close to the coast and it is a very common species in the Foteviken area east of Lillgrund. In
cold ice winters larger flocks can sometimes occur far out in Öresund and it may be that
Lillgrund could be included in its offshore distribution in such situation. We did not find any
larger numbers at sea during the pre-construction years, but during the two hard, ice-winters
in 2010 and 2011 we found some larger flocks on Bredgrund, south of Lillgrund but none in
the Lillgrund area itself. Lacking a very hard winter before construction we cannot evaluate
whether the distribution of this species might be affected by the wind farm in cold winters.
Another diving duck species which could not be studied in relation to the wind farm is the
Tufted Duck Aythya fuligula. Large flocks roost over the day in the ponds at Klagshamn or in
the inner part of Höllviken (Falsterbo Canal) from where they make nocturnal feeding flights
out to offshore foraging areas. From previous analyses of radar data we know that the
foraging areas are mainly situated around the northern tip of Falsterbo peninsula and at
Bredgrund, but it cannot be excluded that Lillgrund may be used in some occasions. So far we
have not seen any movements towards Lillgrund.
For the main study species we analyze the distribution and numbers for each species
separately with the main emphasis to compare the situation pre- and post-construction of the
wind farm at Lillgrund. We show total numbers counted for each main species during the boat
surveys, Fig. 3) and for the aerial surveys, (Fig. 5). For the aerial surveys we separate
between the Northern area (including Lillgrund) and the Southern area (reference area). For
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