United States

United States

Lights and birds not so simple

Regarding "Warning lights for the birds" (Windpower Monthly, June 1998). Although avian problems with wind farms have been found to be low in number generally, it is already known that in some circumstances, very tall lighted structures (i.e. several hundred feet) actually pose a much greater threat to migrating birds than do structures which are not lighted.

I was interested to read that because of concerns that wind turbines were dangerous to migrating birds, authorities at Wakkanai in the north of Japan said that "for good order, we have installed lights on the turbines" (Lights for Birds, June 1998). Although avian problems with wind farms have been found to be low in number generally, the significance of hard-to-measure nocturnal migration numbers, heights and pathways was raised as one high priority research topic at a recent meeting into avian issues in California organised by the US National Wind Coordinating Committee. It is already known, however, that in some circumstances, very tall lighted structures (i.e. several hundred feet) actually pose a much greater threat to migrating birds than do structures which are not lighted.

Under poor weather conditions these lights have been known to attract and confuse nocturnal migrating birds, with the result that many collide and are killed. Although the structure and lighting height limits necessary for this effect were not discussed at the meeting, the issue may become of more concern since turbine size has been increasing to heights that now legally require lighting to meet aeronautical regulations. Will it be necessary to totally avoid nocturnal bird migration pathways?

Although much study has been directed at reducing bird strikes at existing wind turbine installations, there is now just as much (or more) emphasis on scientifically rigorous site selection studies, with added importance given to avian issues. (The NWCC Avian Subcommittee is currently preparing the "Standard Metrics and Methods for Monitoring Avian/Wind Energy Interactions" ).

Still, public education is required regarding misinformed perceptions and the biological significance of the low number of bird strikes (seen so far) in wind power stations. Looked at in perspective, other potential hazards (cats, power lines, communications towers, lighted city buildings) kill birds on much larger (seemingly accepted) scales.

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