ABSTRACT

The risk of birds colliding with wind turbines is known to be highest during dark nights. We studied the flight patterns and altitudes of waders and diving-ducks in tidal and semi-offshore areas, using radar. The birds flew mainly at present-day wind turbine heights (<100 m), both during the day and during darkness. During darkness, waders roosting inland did so more often in or close to shallow water and less in fields away from water than during the day. Observations of wintering diving-ducks near a line of turbines suggest that the collision risk for this species group is probably low. During moonless nights, fewer birds approached the wind farm than during moonlit nights. Of those which approached the turbines, fewer birds passed in between the turbines and more birds turned away from them than during moonlit nights. This data indicates that turbine lines may act as flight path barriers. This should be taken into account in the planning of wind farms.