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

% of all echoes (flocks)
20
15
10
5
0
2002 2005 2008
Year
2009 2010
67
Day-time
Night-time
Fig. 47. The proportion of all bird echoes (bird flocks) with north-easterly flight directions
recorded by radar over southern Öresund during spring 2002 and 2005 pre- and 2008, 2009,
2010 post-construction passing Lillgrund, 3x3 km including the wind farm and its close
surroundings (see Fig. 7 and 40) during day time (open bars) and at night (filled bars)
separately.
Andelen fågelekon (flockar) med nordostliga flygriktningar registrerade med radar som
passerade över själva Lillgrundsområdet under vårarna 2002 och 2005 (före etablering av
vindkraftparken på Lillgrund) samt 2008, 2009 och 2010 (efter att parken tagits i drift) på
dagen (vita staplar) och natten (grå staplar, se Fig. 7 and 40).
Spring- southerly directed migration
General
In addition to the main migratory movements towards northeast in spring there is also a rather
numerous passage of birds towards south (Fig. 48). These movements are mainly made up of
Eiders, wintering in Kattegat and following the Swedish west coast towards south before
entering the Baltic and then turning east and northeast. Other waterfowl such as Common
Scoters are also included in this passage. During analysed days in spring 2002, 2005, 2008
and 2009 annual totals passing the transect 1-4 varied between 200 and 1800 bird echoes
(flocks, Table A12 in appendix). Somewhere in the order of 100 000 birds probably pass with
south oriented flight directions each spring, although Eider numbers have decreased quite
heavily in later years. With same reasoning as above for the main migration route towards
northeast this probably corresponds to between 10 000 and 90 000 individual birds, if average
flock size was around 50 individuals.
The proportion of flocks passing sector 2 with the wind farm area was low both pre- (0-9 % of
the total migration volume) and post (1-7 % of the total migration volume) construction of the
wind farm. There was just a marginal difference between the periods in the proportion of all