This environmental impact assessment for Kriegers flak ... - Vattenfall

The investigations at both wind farms showed that
the birds make way for the turbines well in advance.
At Horns Rev, a change in ß ight path was registered
at a distance of between 400 and 1 000 metres. At
Nysted, the ß ight path changed already at a distance of
3 000 metres during day time and 1 000 metres during
night time. The differences between the wind farms is
probably explained by the different species registered.
The investigations were conducted during one year,
albeit not during days with bad visibility (fog/rain).
Further, only larger water fowl and day migrating birds
could be registered. The results from the investigations
should, therefore, be treated with caution.
The collision risk depends on several different
factors. As mentioned above, the weather has a great
impact but the risk is also due to the species. An investigation
of 190 bird species that have collided with
a Danish lighthouse, show that Þ ve species made up
for 75 % of the casualties (Hansen, 1954). These were
Eurasian skylark, song thrush, redwing, dipper and
European robin. About 90 % came from 14 different
species, all of which were night ß yers. Of all birds
observed, very few were day ß yers and only three were
thermal ß yers.
IfAÖ has in its report estimated annual collisions
to 1 000. The risk of water fowl, such as ducks, geese,
eider ducks, seagulls, terns and loons, would collide
with wind turbines is considered as low. As thermal
ß yers normally ß y at much higher heights and as their
eyesight is well developed, the risk for collision is low.
In addition, ß ights over open sea by thermal ß yers
CONSEQUENSES OF THE WIND FARM 131
occurs seldom. Most collision victims will most likely
be middle distance ß yers with very large breeding
stocks in Scandinavia, for example Eurasian skylarks,
thrushes and dippers. In relation to breeding stocks of
Scandinavian night ß yers (500 – 600 million), the annual
maximum mortality quota is estimated to 0,002%.
The IfAÖ considers that this quota will not have any
negative impact on migrating birds (page 117, stocks
decrease).
Jan Pettersson has, on behalf of Sweden Offshore,
estimated the annual collision (Attachment 8.4). Jan
Pettersson has estimated the number of annual collisions
to 48, a much lower number than that of the
IfAÖ.
b) Disturbance of staging and foraging water fowl
Wind turbines may also frighten breeding, staging and
foraging birds. The effect varies for different species.
Seagulls and terns are regularly observed at Horns
Rev. During the construction phase, the frightening
effect may become big due to transports and construction
work. There are currently no studies made on the
impact of noise and vibrations on birds.
c) Barrier effect
Here, barrier effect means that migrating birds to
avoid the wind farm make a detour in their ß ight. As
the planned wind farm will occupy such a large area,
it is conceivable that migrating birds will act similarly
to the wind farm as to islands, namely to ß y over the
area at several hundred metres height. This type of
behaviour has been registered at onshore objects with,
for example common scoter, loons and long-tailed duck
(Bergman & Donner, 1964, Berndt & Busche, 1993).
The above studies at Horns Rev, Nysted and Utgrunden
have shown that large scale wind farms do have barrier
effects even if there are species speciÞ c differences.
For common scoters and loons, wind farm are examples
of barriers whilst eider ducks ß y through, although
if mainly around them. Wind farms are no barriers for
seagulls, terns and most thermal ß yers, as the latter
often ß y higher than the wind turbines.
The important question regarding barrier effects, is
whether the detour gives rise to any relevant increase
in energy consumption. Considering the high, natural
variations of ß ights and their total distance, IfAÖ estimates
the extra load for the affected species as minor.