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

Discussion
Staging and wintering birds
As stated already in the introduction, in earlier reports from the project (Green & Nilsson
2006, Nilsson 2001) and in reports from the Öresund Bridge project (Nilsson 1996a, 1996b,
1998), the southern part of Öresund is an important area for a number of water bird species,
several of them occurring in internationally important numbers. Even if the water birds of
southern Öresund had been studied for a long time, the offshore parts had only been surveyed
on a few occasions in connection with studies of wintering diving ducks around the coasts of
Scania (Nilsson 1972, unpubl.). During the base-line studies for the Lillgrund wind farm it
was established that the areas around Lillgrund together with neighboring shallow areas at
Bredgrund was an important staging and wintering area, especially for Red-breasted
Mergansers but also for Eiders (Green & Nilsson 2006). Smaller numbers of wintering Longtailed
Ducks were also found in the area, whereas other species were only found in small
numbers, note however the nocturnal feeding flights for the Tufted Ducks to the Bredgrund
area (and maybe also to Lillgrund) discussed above (see also Nilsson 1972).
Among the wintering waterfowl species the large concentration of Red-breasted Mergansers
occurring in the area was not known before the base-line studies. This concentration is
actually the largest for the species in the entire Baltic (Durinck et al. 1994, SOWBAS
unpubl.). The wintering Red-breasted Mergansers, estimated to be up to 12 000 individuals,
form an important part of the northwestern European population.
For the other two sea ducks, the Eider and the Long-tailed Duck, the area is not of the same
importance as a staging area and wintering area as it is for the Red-breasted Merganser. The
Long-tailed Duck has its main winter distribution in the Baltic and numbers around the coasts
of Scania has decreased markedly during the last few decades. The main concentrations occur
in the central parts of the Baltic proper, the southern parts of Öresund is just a marginal
wintering area for the species. The Eider is a common wintering bird in the area, mainly in the
reference parts south of Falsterbo but wintering birds do also occurs in the Lillgrund area and
all the way northwards along the Öresund and the Swedish west coast. The spring situation is
different as Lillgrund is close to the important breeding colony on Saltholm with between
4000 and 5000 breeding pairs in 2000 (Desholm et al. 2002). The area is also used as a
stopover area during spring migration.
Besides the three duck species mentioned above Herring Gulls were regular and fairly
common in the southern part of the Öresund during our surveys. Moreover, the southern part
of the Öresund is also used by larger numbers of Cormorants during winter (Bengtsson 1999,
2000). Flocks of several thousand individuals have regularly been seen fishing in Öresund
using Saltholm and Pepparholm for roosting. Other seabirds were only found in small
numbers during the base-line studies.
In this report from the monitoring program we have focused on the five main species
mentioned above, these species being the only ones where it was likely to find any possible
impact from the wind farm.
The staging and wintering water birds in the Lillgrund area were surveyed both from a boat
and from the air. It was clear from the start of the program that both methods should be used
considering both the logistics of offshore surveys and differences in detectability of different
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