Current research on wind powered generators and the recent announcement that a single machine, with 60m rotors and producing 3MW, is to be built on Orkney have raised the possibility of risk to birds through impact. Plans have been produced for machines with rotors up to 100m (diameter) operating from towers 125m high. Production installations of such machines are likely to take the form of arrays, in areas subject to windy conditions, set across the direction from which prevailing wind blows. This document sets out to examine the liklihood of direct loss to bird life through impact with the moving rotors of such machines and possible means of avoiding such losses. It does not consider the effect of the structures, their construction or maintenance on the composition of local bird communities.
Four sections follow dealing with particular aspects of the problem.
- The probability of collision. This examines the liklihood of a bird being struck by a moving rotor in the absence of any attraction to or avoidance of the machine being shown by the bird.
- Local birds at risk. This section discusses the species that might be at risk, possible behaviour which may affect the risk to which they are exposed and steps which might be taken to reduce the risk.
- Migrant birds at risk. The height at which migrants fly and the chances of impact, particularly at night, are examined together with the bird's behaviour and possibilities of reducing risk.