Common
Eider (Somateria Mollissima)© 1996 Søren Krohn
Birds
and Wind Turbines
Birds often collide with high voltage overhead lines, masts,
poles, and windows of buildings. They are also killed by cars
in the traffic.
Birds are seldom bothered by wind turbines,
however. Radar studies from Tjaereborg in the western part of
Denmark, where a 2 megawatt wind turbine with 60 metre rotor
diameter is installed, show that birds - by day or night - tend
to change their flight route some 100-200 metres before the turbine
and pass above the turbine at a safe distance.
In Denmark there are several examples of
birds (falcons) nesting in cages mounted on wind turbine towers.
The only known site with bird collision problems
is located in the Altamont Pass in California. Even there, collisions
are not common, but they are of extra concern because the species
involved are protected by law.
A study from the Danish Ministry of the Environment
says that power lines, including power lines leading to wind
farms, are a much greater danger to birds than the wind turbines
themselves.
Some birds get accustomed to wind turbines
very quickly, others take a somewhat longer time. The possibilities
of erecting wind farms next to bird sanctuaries therefore depend
on the species in question. Migratory routes of birds will usually
be taken into account when siting wind farms, although bird studies
from Yukon show that migratory birds do not collide with wind
turbines.